Showing 1–50 of 146 results for author: Strauss, R

Sensitivity enhancement techniques for cryogenic calorimeters in the NUCLEUS experiment

Authors: M. Cappelli, A. Wallach, H. Abele, G. Angloher, B. Arnold, M. Atzori Corona, A. Bento, E. Bossio, F. Buchsteiner, J. Burkhart, F. Cappella, N. Casali, R. Cerulli, A. Cruciani, G. Del Castello, M. del Gallo Roccagiovine, S. Dorer, A. Erhart, M. Friedl, S. Fichtinger, V. M. Ghete, M. Giammei, C. Goupy, J. Hakenmüller, D. Hauff , et al. (40 additional authors not shown)

Abstract: Phonon-mediated cryogenic calorimeters find application in rare event searches due to their intrinsically low energy threshold. Achieving the best sensitivity for this kind of detectors is crucial for signal identification, leading to various optimization techniques. In this work, we present two complementary methods to increase the sensitivity of cryogenic detectors read out by transition-edge se… ▽ More Phonon-mediated cryogenic calorimeters find application in rare event searches due to their intrinsically low energy threshold. Achieving the best sensitivity for this kind of detectors is crucial for signal identification, leading to various optimization techniques. In this work, we present two complementary methods to increase the sensitivity of cryogenic detectors read out by transition-edge sensors, developed and tested in the context of the NUCLEUS experiment. The first procedure maps the signal-to-noise ratio of the device across a wide range of operating points, to identify the configuration with maximal sensitivity to be used during data taking. The second method exploits the double readout of the detector, combining the information on different channels with a two-dimensional optimum filter analysis that effectively lowers the energy threshold. With both techniques at the same time, we obtained a baseline resolution of 2.94 $\pm$ 0.05 (stat) eV using a CaWO4 based detector, achieving a promising result in view of the first run of NUCLEUS at the experimental site. △ Less

Submitted 30 March, 2026; originally announced March 2026.

Prospect of the NUCLEUS Experiment at Chooz for Coherent Elastic Neutrino-Nucleus Scattering and New Physics Searches

Authors: H. Abele, G. Angloher, B. Arnold, M. Atzori Corona, A. Bento, E. Bossio, F. Buchsteiner, J. Burkhart, F. Cappella, M. Cappelli, N. Casali, R. Cerulli, A. Cruciani, G. Del Castello, M. del Gallo Roccagiovine, S. Dorer, A. Erhart, M. Friedl, S. Fichtinger, V. M. Ghete, M. Giammei, C. Goupy, J. Hakenmüller, D. Hauff, F. Jeanneau , et al. (40 additional authors not shown)

Abstract: The NUCLEUS experiment aims to measure coherent elastic neutrino-nucleus scattering (CE$ν$NS) at unprecedentedly low nuclear recoil energies using gram-scale cryogenic calorimeters operated at the Chooz nuclear power plant in France. Access to recoil energies at the $\mathcal{O}(10~\mathrm{eV})$ scale enables CE$ν$NS studies at extremely low momentum transfer and provides enhanced sensitivity to n… ▽ More The NUCLEUS experiment aims to measure coherent elastic neutrino-nucleus scattering (CE$ν$NS) at unprecedentedly low nuclear recoil energies using gram-scale cryogenic calorimeters operated at the Chooz nuclear power plant in France. Access to recoil energies at the $\mathcal{O}(10~\mathrm{eV})$ scale enables CE$ν$NS studies at extremely low momentum transfer and provides enhanced sensitivity to new physics. In this work, we present sensitivity projections for the upcoming NUCLEUS technical and physics runs, incorporating a data-driven treatment of the low-energy excess (LEE) observed during commissioning. We develop a likelihood framework that exploits reactor-power variation to disentangle signal and background in a low signal-to-background regime and to assess the impact of the dominant systematic uncertainties. For the Technical Run with a 7 g CaWO$_4$ target, we find competitive sensitivity to several scenarios beyond the Standard Model, which do not require a CE$ν$NS observation. For the Physics Run, assuming complete suppression of the LEE, we project a 4.7 $σ$ observation of CE$ν$NS with a statistical precision of about 20 % in 1 year, enabling a determination of the weak mixing angle at the lowest momentum transfer probed to date with CE$ν$NS and leading CE$ν$NS-based constraints on the neutrino charge radius and new mediator models. △ Less

Submitted 25 March, 2026; originally announced March 2026.

Multi-spacecraft constraints on relativistic solar energetic particle transport in the widespread 28 October 2021 event

Authors: E. Lavasa, J. T. Lang, A. Papaioannou, R. D. Strauss, S. A. Mallios, A. Hillaris, A. Kouloumvakos, A. Anastasiadis, I. A. Daglis

Abstract: Aims. We investigated the transport of solar energetic particles (SEPs) during the relativistic widespread event of 28 October 2021, quantifying the role of parallel and perpendicular diffusion and constraining the spatial extent of the injection region. Methods. We employed inverse modeling of particle focused transport and 2D numerical simulations including cross-field diffusion. Multi-spacecraf… ▽ More Aims. We investigated the transport of solar energetic particles (SEPs) during the relativistic widespread event of 28 October 2021, quantifying the role of parallel and perpendicular diffusion and constraining the spatial extent of the injection region. Methods. We employed inverse modeling of particle focused transport and 2D numerical simulations including cross-field diffusion. Multi-spacecraft observations from STEREO-A, Solar Orbiter, and near-Earth spacecraft are used to reproduce particle intensity profiles and anisotropies across a wide range of electron and proton energies. Simulated flux profiles are compared across different heliolongitudes to derive consistent transport parameters. Results. The analysis yields parallel mean free paths within or slightly above the Palmer consensus range, and perpendicular mean free paths that correspond to $\sim 1$--$3\%$ of parallel for electrons and $\sim 5$--$10\%$ for protons. The injection region is found to be relatively narrow ($\leq 20^\circ$), and decreasing with particle rigidity. Multipoint simulations indicate that the observed flux and anisotropy profiles can only be reproduced by a narrow injection region and significant cross-field diffusion. Electron and proton release times align well with the parent X1.0 flare and associated coronal mass injection (CME) onset, indicating that a compact acceleration region coupled with efficient interplanetary diffusion governed the event's broad spatial extent. △ Less

Submitted 10 March, 2026; originally announced March 2026.

Journal ref: A&A, 707 (2026) A12

Characterization of the Low Energy Excess using a NUCLEUS $Al_2O_3$ detector

Authors: H. Abele, G. Angloher, B. Arnold, M. Atzori Corona, A. Bento, E. Bossio, F. Buchsteiner, J. Burkhart, F. Cappella, M. Cappelli, N. Casali, R. Cerulli, A. Cruciani, G. Del Castello, M. del Gallo Roccagiovine, S. Dorer, A. Erhart, M. Friedl, S. Fichtinger, V. M. Ghete, M. Giammei, C. Goupy, J. Hakenmüller, D. Hauff, F. Jeanneau , et al. (40 additional authors not shown)

Abstract: The NUCLEUS experiment aims to detect coherent elastic neutrino-nucleus scattering of reactor antineutrinos using low-threshold, gram-scale cryogenic calorimeters. Similar to other low-threshold experiments, NUCLEUS observes a sharp rise in the event rate below a few hundred eV, referred to as the low energy excess (LEE), whose origin remains yet unidentified. Building on results from the NUCLEUS… ▽ More The NUCLEUS experiment aims to detect coherent elastic neutrino-nucleus scattering of reactor antineutrinos using low-threshold, gram-scale cryogenic calorimeters. Similar to other low-threshold experiments, NUCLEUS observes a sharp rise in the event rate below a few hundred eV, referred to as the low energy excess (LEE), whose origin remains yet unidentified. Building on results from the NUCLEUS testing and commissioning at the Technical University of Munich and from previous characterization campaigns, we present a comprehensive study of the background rate measured with a sapphire detector equipped with two transition-edge sensors under various experimental conditions. We find no evidence for a dependence of the LEE rate on the particle background level, whereas the results indicate that slower cooling-down procedures lead to lower initial LEE rates. The behavior of the LEE rate during the same cooldown is comparable across the measurements and is best described by a power law with a common exponent across datasets of $(-0.59 \pm 0.06)$, when time is expressed from the moment the detector reaches the 4 K temperature. These findings provide valuable guidance for future LEE mitigation strategies in the NUCLEUS experiment. △ Less

Submitted 8 March, 2026; originally announced March 2026.

Comments: 20 pages, 10 figures

ImpCresst -- A versatile simulation tool focusing on solid-state detectors at keV energies

Authors: G. Angloher, S. Banik, A. Bento, A. Bertolini, R. Breier, C. Bucci, J. Burkhart, L. Burmeister, L. Canonica, F. Casadei, E. Cipelli, S. Di Lorenzo, J. Dohm, F. Dominsky, A. Erb, E. Fascione, F. von Feilitzsch, S. Fichtinger, D. Fuchs, A. Fuss, V. M. Ghete, P. Gorla, P. V. Guillaumon, D. Hauff, M. Ješkovský , et al. (35 additional authors not shown)

Abstract: We present ImpCresst, a Geant4-based Monte Carlo tool to simulate backgrounds from natural and cosmogenic radionuclides, and calibration signals in solid-state detectors and their response to it. It is tuned for a fast-evolving and heterogeneous detector environment with a focus on physics at the keV range. This tool was originally developed and validated by the CRESST collaboration; however, its… ▽ More We present ImpCresst, a Geant4-based Monte Carlo tool to simulate backgrounds from natural and cosmogenic radionuclides, and calibration signals in solid-state detectors and their response to it. It is tuned for a fast-evolving and heterogeneous detector environment with a focus on physics at the keV range. This tool was originally developed and validated by the CRESST collaboration; however, its flexibility and configurability make it suitable for other experiments with similar requirements. Key features of ImpCresst include the dynamic geometry implementation directly from CAD files, ROOT-based data persistency of the whole event topology and automatic metadata annotation for data provenance, and interfaces to various particle generators, particularly for radiogenic and cosmogenic radionuclides. It includes also a newly developed particle generator for radioactive bulk and surface contaminations which is completely independent of any user defined confinement volumes. The auxiliary tool CresstDS applies detector-specific energy and time resolution based on a user-provided data set of empirical parameterization. We discuss also how to manage an ImpCresst based workflow in an HPC environment based on Apptainer and nextflow. △ Less

Submitted 2 March, 2026; originally announced March 2026.

Anomalous cosmic rays within the inner heliosphere: Observations of helium by the High Energy Telescope onboard Solar Orbiter

Authors: Zigong Xu, Robert F. Wimmer-Schweingruber, Lars Berger, Patrick Kühl, Alexander Kollhoff, Bernd Heber, Stephan I. Böttcher, Liu Yang, Verena Heidrich-Meisner, Roelf Du Toit Strauss, Raúl Gomez-Herrero, Javier Rodriguez-Pacheco, Daniel Pacheco, Richard A. Leske

Abstract: Radial gradients of cosmic rays are key parameters for understanding the transport of particles in space. Solar Orbiter, launched on 2020 February 10, approaches the Sun approximately every half year, with a closest perihelion distance of 0.29 au after the end of 2022 during the nominal mission phase. The two double-ended high energy telescopes(HET)onboard the Solar Orbiter measure energetic parti… ▽ More Radial gradients of cosmic rays are key parameters for understanding the transport of particles in space. Solar Orbiter, launched on 2020 February 10, approaches the Sun approximately every half year, with a closest perihelion distance of 0.29 au after the end of 2022 during the nominal mission phase. The two double-ended high energy telescopes(HET)onboard the Solar Orbiter measure energetic particles in the energy range between a few MeV/nuc and a few hundred MeV/nuc, which are dominated by anomalous cosmic rays (ACRs) and galactic cosmic rays (GCRs) during solar quiet times. By obtaining the radial gradient of the ACR helium in the inner heliosphere, we advance our understanding of how the transport of the cosmic rays is affected by the particle drift effect and the large-scale magnetic field. The helium observations at Solar Orbiter/HET between 11.1 and 49 MeV/nuc are analyzed. Since we focus on quiet time measurements, we remove the periods of solar energetic particle (SEP) events. The intensities are averaged over the Carrington rotation period. The helium observations from the Proton and Helium Instrument(EPHIN)onboard SOHO were utilized as the baseline to correct the long-term variation caused by the solar modulations. We present the first observation of ACR helium at Solar Orbiter/HET between 2020 February and 2022 July in the inner heliosphere before the sun became fully active. We derive the radial gradient of the ACR helium between 0.3 and 1 au. The averaged radial gradient between 11.1 and 49MeV/nuc is about 22$\pm$4%/au and the averaged value between 11.1 and 41.2MeV/nuc is raised to 32$\pm$8%/au after removing the GCR contribution, which is estimated by a GCR model. In addition, the temporal variation of radial gradients indicates that the gradients are increasing with the enhancement of the solar modulation and the increased tilt angle of the heliospheric current sheet. △ Less

Submitted 25 February, 2026; originally announced February 2026.

Comments: 12 pages, 5 figures; Accepted by A&A

Journal ref: A&A 708, A36 (2026)

First Detailed MeerKAT Imaging Spectroscopy of a Solar Flare

Authors: Yingjie Luo, Eduard P. Kontar, Roelf Du Toit Strauss, Gert J. J. Botha, Tomasz Mrozek, Gelu M. Nita, Sarah Buchner, James O. Chibueze

Abstract: Radio observations provide powerful diagnostics of energy release, particle acceleration, and transport processes in solar flares. However, despite recent progress in radio interferometric imaging spectroscopy, current instruments still face limitations in image fidelity and resolution, restricting detailed spectroscopic studies of flaring regions. Here we present high-fidelity imaging spectroscop… ▽ More Radio observations provide powerful diagnostics of energy release, particle acceleration, and transport processes in solar flares. However, despite recent progress in radio interferometric imaging spectroscopy, current instruments still face limitations in image fidelity and resolution, restricting detailed spectroscopic studies of flaring regions. Here we present high-fidelity imaging spectroscopy of a M1.3 GOES class flare with MeerKAT, a precursor to the future-generation array SKA-Mid. Radio emissions at the observed frequencies typically originate in the low corona, offering valuable insights into magnetic reconnection and primary energy-release sites. The obtained images achieve an unprecedented dynamic range exceeding 10^3, enabling simultaneous analysis of bright coherent bursts and faint incoherent emission from the active region. Multiple spatially distinct coherent sources are identified, implying contributions from different populations of accelerated electrons. The incoherent emission extends beyond AIA structures, highlighting MeerKAT's ability to detect dilute but hot plasma invisible to Extreme Ultraviolet instruments. Combined with co-temporal Hard X-ray images and magnetic field extrapolations, the radio sources are located within distinct magnetic structures, further revealing their association with different populations of accelerated electrons. These results demonstrate MeerKAT imaging spectroscopy as powerful diagnostics of solar flares and pave the way for future solar flare studies with SKA-Mid. △ Less

Submitted 4 February, 2026; originally announced February 2026.

Comments: Accepted for publication in ApJL. 12 pages, 5 figures

Journal ref: The Astrophysical Journal Letters, Volume 998, Number 2, 2026

Observation of two nuclear recoil peaks induced by neutron capture on Al2O3

Authors: H. Abele, P. Ajello, B. Arnold, E. Bossio, J. Burkhart, F. Cappella, N. Casali, R. Cerulli, J-P. Crocombette, G. del Castello, M. del Gallo Roccagiovine, P. de Marcillac, S. Dorer, C. Doutre, A. Erhart, S. Fichtinger, M. Friedl, C. Goupy, D. Hauff, E. Jericha, M. Kaznacheeva, H. Kluck, T. Lasserre, D. Lhuillier, O. Litaize , et al. (21 additional authors not shown)

Abstract: We report the observation of two nuclear recoil peaks induced by neutron capture on aluminum in a cryogenic Al$_2$O$_3$ detector developed by the NUCLEUS collaboration for the detection of reactor neutrinos via coherent elastic neutrino-nucleus (CEvNS) process. Data collected at the Technical University of Munich in 2024 with a $^{252}$Cf source reveal a main recoil line at 1145 eV from single-… ▽ More We report the observation of two nuclear recoil peaks induced by neutron capture on aluminum in a cryogenic Al$_2$O$_3$ detector developed by the NUCLEUS collaboration for the detection of reactor neutrinos via coherent elastic neutrino-nucleus (CEvNS) process. Data collected at the Technical University of Munich in 2024 with a $^{252}$Cf source reveal a main recoil line at 1145 eV from single-$γ$ de-excitation of $^{28}$Al and a newly observed structure near 575 eV originating from several two-$γ$ cascades. The latter constitutes the first direct measurement of a nuclear recoil line induced by multi-$γ$ cascades. It is predicted by our simulations when the recoiling nucleus has time to stop before the emission of the next $γ$-ray in the cascade. These results demonstrate the potential performance of the CRAB (Calibration Recoil for Accurate Bolometry) method for in situ nuclear recoil calibration and highlight the importance of accurately modeling recoil stopping and nuclear de-excitation times in cryogenic detectors of CEvNS and dark matter interactions. △ Less

Submitted 6 December, 2025; originally announced December 2025.

Comments: 9 pages, 9 figures

An Efficient Shift-and-Stack Algorithm Applied to Detection Catalogs

Authors: Steven Stetzler, Mario Jurić, Pedro H. Bernardinelli, Dino Bektešević, Colin Orion Chandler, Andrew J. Connolly, Fred C. Adams, Cesar Fuentes, David W. Gerdes, Matthew J. Holman, Hsing Wen Lin, Larissa Markwardt, Andrew McNeill, Michael Mommert, Kevin J. Napier, William J. Oldroyd, Matthew J. Payne, Andrew S. Rivkin, Luis E. Salazar-Manzano, Hilke Schlichting, Scott S. Sheppard, Dallin Spencer, Ryder Strauss, David E. Trilling, Chadwick A. Trujillo

Abstract: The boundary of solar system object discovery lies in detecting its faintest members. However, their discovery in detection catalogs from imaging surveys is fundamentally limited by the practice of thresholding detections at signal-to-noise (SNR) $\geq 5$ to maintain catalog purity. Faint moving objects can be recovered from survey images using the shift-and-stack algorithm, which coadds pixels fr… ▽ More The boundary of solar system object discovery lies in detecting its faintest members. However, their discovery in detection catalogs from imaging surveys is fundamentally limited by the practice of thresholding detections at signal-to-noise (SNR) $\geq 5$ to maintain catalog purity. Faint moving objects can be recovered from survey images using the shift-and-stack algorithm, which coadds pixels from multi-epoch images along a candidate trajectory. Trajectories matching real objects accumulate signal coherently, enabling high-confidence detections of very faint moving objects. Applying shift-and-stack comes with high computational cost, which scales with target object velocity, typically limiting its use to searches for slow-moving objects in the outer solar system. This work introduces a modified shift-and-stack algorithm that trades sensitivity for speedup. Our algorithm stacks low SNR detection catalogs instead of pixels, the sparsity of which enables approximations that reduce the number of stacks required. Our algorithm achieves real-world speedups of $10$--$10^3 \times$ over image-based shift-and-stack while retaining the ability to find faint objects. We validate its performance by recovering synthetic inner and outer solar system objects injected into images from the DECam Ecliptic Exploration Project (DEEP). Exploring the sensitivity--compute time trade-off of this algorithm, we find that our method achieves a speedup of $\sim30\times$ with $88\%$ of the memory usage while sacrificing $0.25$ mag in depth compared to image-based shift-and-stack. These speedups enable the broad application of shift-and-stack to large-scale imaging surveys and searches for faint inner solar system objects. We provide a reference implementation via the find-asteroids Python package and this URL: https://github.com/stevenstetzler/find-asteroids. △ Less

Submitted 30 September, 2025; originally announced September 2025.

Comments: 35 pages, 15 figures, accepted for publication in The Astronomical Journal

Particle background characterization and prediction for the NUCLEUS reactor CE$ν$NS experiment

Authors: H. Abele, G. Anglogher, B. Arnold, M. Atzori Corona, A. Bento, E. Bossio, F. Buchsteiner, J. Burkhart, F. Cappella, M. Cappelli, N. Casali, R. Cerulli, A. Cruciani, G. Del Castello, M. del Gallo Roccagiovine, S. Dorer, A. Erhart, M. Friedl, S. Fichtinger, V. M. Ghete, M. Giammei, C. Goupy, D. Hauff, F. Jeanneau, E. Jericha , et al. (35 additional authors not shown)

Abstract: NUCLEUS is a cryogenic detection experiment which aims to measure Coherent Elastic Neutrino-Nucleus Scattering (CE$ν$NS) and to search for new physics at the Chooz nuclear power plant in France. This article reports on the prediction of particle-induced backgrounds, especially focusing on the sub-keV energy range, which is a poorly known region where most of the CE$ν$NS signal from reactor antineu… ▽ More NUCLEUS is a cryogenic detection experiment which aims to measure Coherent Elastic Neutrino-Nucleus Scattering (CE$ν$NS) and to search for new physics at the Chooz nuclear power plant in France. This article reports on the prediction of particle-induced backgrounds, especially focusing on the sub-keV energy range, which is a poorly known region where most of the CE$ν$NS signal from reactor antineutrinos is expected. Together with measurements of the environmental background radiations at the experimental site, extensive Monte Carlo simulations based on the Geant4 package were run both to optimize the experimental setup for background reduction and to estimate the residual rates arising from different contributions such as cosmic ray-induced radiations, environmental gammas and material radioactivity. The NUCLEUS experimental setup is predicted to achieve a total rejection power of more than two orders of magnitude, leaving a residual background component which is strongly dominated by cosmic ray-induced neutrons. In the CE$ν$NS signal region of interest between 10 and 100 eV, a total particle background rate of $\sim$ 250 d$^{-1}$kg$^{-1}$keV$^{-1}$ is expected in the CaWO$_4$ target detectors. This corresponds to a signal-to-background ratio $\gtrsim$ 1, and therefore meets the required specifications in terms of particle background rejection for the detection of reactor antineutrinos through CE$ν$NS. △ Less

Submitted 3 November, 2025; v1 submitted 3 September, 2025; originally announced September 2025.

Comments: 30 pages, 12 figures, 5 tables

Journal ref: Eur. Phys. J. C 86, 29 (2026)

Eliminating Tokamak Disruptions with Feedback

Authors: H. R. Strauss

Abstract: Many disruptions are caused by resistive wall tearing modes (RWTM). A database of DIII-D locked mode disruptions provides two main disruption criteria, which are shown to be signatures of RWTMs. The first is that the q = 2 rational surface must be sufficiently close the resistive wall surrounding the plasma to interact with it. If active feedback is used, this implies that RWTMs can be prevented f… ▽ More Many disruptions are caused by resistive wall tearing modes (RWTM). A database of DIII-D locked mode disruptions provides two main disruption criteria, which are shown to be signatures of RWTMs. The first is that the q = 2 rational surface must be sufficiently close the resistive wall surrounding the plasma to interact with it. If active feedback is used, this implies that RWTMs can be prevented from causing major disruptions. This is demonstrated in simulations. The second criterion is that the current profile is sufficiently peaked. This is caused by edge cooling, such as by impurity radiation and turbulence, which suppress edge current and temperature. This implies the disruptions are not caused by neoclassical tearing modes (NTM), because the bootstrap current is also suppressed. The dependence of the critical internal inductance on elongation is given, which suggests that elongation might be used as an actuator to prevent disruptions. At high $β,$ resistive wall modes (RWM) can be stabilized with feedback. Feedback also stabilizes high $β$ RWTMs, as shown in NSTX data and in simulations. These results suggest that RWTM disruptions in ITER might be prevented using the resonant magnetic perturbation (RMP) coils. △ Less

Submitted 10 September, 2025; v1 submitted 18 August, 2025; originally announced August 2025.

Description of CRESST-III lithium aluminate data

Authors: G. Angloher, S. Banik, G. Benato, A. Bento, A. Bertolini, R. Breier, C. Bucci, J. Burkhart, L. Canonica, A. D'Addabbo, S. Di Lorenzo, L. Einfalt, A. Erb, F. v. Feilitzsch, N. Ferreiro Iachellini, S. Fichtinger, D. Fuchs, A. Fuss, A. Garai, V. M. Ghete, P. Gorla, P. V. Guillaumon, S. Gupta, D. Hauff, M. Ješkovský , et al. (36 additional authors not shown)

Abstract: Two detector modules with lithium aluminate targets were operated in the CRESST underground setup between February and June 2021. The data collected in this period was used to set the currently strongest cross-section upper limits on the spin-dependent interaction of dark matter (DM) with protons and neutrons for the mass region between 0.25 and 1.5 GeV/c$^2$. The data are available online. In thi… ▽ More Two detector modules with lithium aluminate targets were operated in the CRESST underground setup between February and June 2021. The data collected in this period was used to set the currently strongest cross-section upper limits on the spin-dependent interaction of dark matter (DM) with protons and neutrons for the mass region between 0.25 and 1.5 GeV/c$^2$. The data are available online. In this document, we describe how the data set should be used to reproduce our dark matter results. △ Less

Submitted 2 September, 2025; v1 submitted 5 August, 2025; originally announced August 2025.

Comments: 4 pages, 2 figures

Description of CRESST-II and CRESST-III pulse shape data

Authors: G. Angloher, S. Banik, D. Bartolot, G. Benato, A. Bento, A. Bertolini, R. Breier, C. Bucci, J. Burkhart, L. Canonica, A. D'Addabbo, S. Di Lorenzo, L. Einfalt, A. Erb, F. v. Feilitzsch, N. Ferreiro Iachellini, S. Fichtinger, D. Fuchs, A. Fuss, A. Garai, V. M. Ghete, P. Gorla, P. V. Guillaumon, S. Gupta, D. Hauff , et al. (40 additional authors not shown)

Abstract: A set of data from 68 cryogenic detectors operated in the CRESST dark matter search experiment between 2013 and 2019 was collected and labeled to train binary classifiers for data cleaning. Here, we describe the data set and how the trained models can be applied to new data. The data and models are available online. A set of data from 68 cryogenic detectors operated in the CRESST dark matter search experiment between 2013 and 2019 was collected and labeled to train binary classifiers for data cleaning. Here, we describe the data set and how the trained models can be applied to new data. The data and models are available online. △ Less

Submitted 5 August, 2025; originally announced August 2025.

Comments: 5 pages, 1 figure, 4 tables

Commissioning of the NUCLEUS Experiment at the Technical University of Munich

Authors: H. Abele, G. Angloher, B. Arnold, M. Atzori Corona, A. Bento, E. Bossio, F. Buchsteiner, J. Burkhart, F. Cappella, M. Cappelli, N. Casali, R. Cerulli, A. Cruciani, G. Del Castello, M. del Gallo Roccagiovine, S. Dorer, A. Erhart, M. Friedl, S. Fichtinger, V. M. Ghete, M. Giammei, C. Goupy, D. Hauff, F. Jeanneau, E. Jericha , et al. (35 additional authors not shown)

Abstract: The NUCLEUS experiment aims to detect coherent elastic neutrino-nucleus scattering of reactor antineutrinos on CaWO$_4$ targets in the fully coherent regime, using gram-scale cryogenic calorimeters. The experimental apparatus will be installed at the Chooz nuclear power plant in France, in the vicinity of two 4.25 GW$_{\text{th}}$ reactor cores. This work presents results from the commissioning of… ▽ More The NUCLEUS experiment aims to detect coherent elastic neutrino-nucleus scattering of reactor antineutrinos on CaWO$_4$ targets in the fully coherent regime, using gram-scale cryogenic calorimeters. The experimental apparatus will be installed at the Chooz nuclear power plant in France, in the vicinity of two 4.25 GW$_{\text{th}}$ reactor cores. This work presents results from the commissioning of an essential version of the experiment at the shallow Underground Laboratory of the Technical University of Munich. For the first time, two cryogenic target detectors were tested alongside active and passive shielding systems. Over a period of two months all detector subsystems were operated with stable performance. Background measurements were conducted, providing important benchmarks for the modeling of background sources at the reactor site. Finally, we present ongoing efforts to upgrade the detector systems in preparation for a technical run at Chooz in 2026, and highlight the remaining challenges to achieving neutrino detection. △ Less

Submitted 29 October, 2025; v1 submitted 4 August, 2025; originally announced August 2025.

Comments: 20 pages, 21 figures

Journal ref: Phys. Rev. D 112, 072013, 2025

Fundamental Nuclear and Particle Physics At Neutron Sources

Authors: H. Abele, J. Amaral, W. R. Anthony, L. AAstrand, M. Atzori Corona, S. Baessler, M. Bartis, E. Baussan, D. H. Beck, J. Bijnens, K. Bodek, J. Bosina, E. Bossio, G. Brooijmans, L. J. Broussard, G. Brunetti, A. Burgman, M. Cadeddu, N. Cargioli, J. Cederkall, A. Chambon, T. W. Choi, P. Christiansen, V. Cianciolo, C. B. Crawford , et al. (99 additional authors not shown)

Abstract: Fundamental neutron and neutrino physics at neutron sources, combining precision measurements and theory, can probe new physics at energy scales well beyond the highest energies probed by the LHC and possible future high energy collider facilities. The European Spallation Source (ESS) will in the not too far future be a most powerful pulsed neutron source and simultaneously the world's brightest p… ▽ More Fundamental neutron and neutrino physics at neutron sources, combining precision measurements and theory, can probe new physics at energy scales well beyond the highest energies probed by the LHC and possible future high energy collider facilities. The European Spallation Source (ESS) will in the not too far future be a most powerful pulsed neutron source and simultaneously the world's brightest pulsed neutrino source. The ESS, and neutron sources in general, can provide unprecedented and unique opportunities to contribute to the search for the missing elements in the Standard Model of particle physics. Currently there are no strong indications where hints of the origin of the new physics will emerge. A multi-pronged approach will provide the fastest path to fill the gaps in our knowledge and neutron sources have a pivotal role to play. To survey the ongoing and proposed physics experiments at neutron sources and assess their potential impact, a workshop was held at Lund University in January, 2025. This report is a summary of that workshop and has been prepared as input to the European Strategy Update. △ Less

Submitted 27 June, 2025; originally announced June 2025.

Comments: Report of the Workshop on fundamental neutron and neutrino physics at neutron sources, 84 pages, 37 figures

Observation of a low energy nuclear recoil peak in the neutron calibration data of an Al$_{2}$O$_{3}$ crystal in CRESST-III

Authors: CRESST Collaboration, G. Angloher, S. Banik, A. Bento, A. Bertolini, R. Breier, C. Bucci, L. Burmeister, F. Casadei, E. Cipelli, J. Burkhart, L. Canonica, J. Dohm, F. Dominsky, S. Di Lorenzo, L. Einfalt, A. Erb, E. Fascione, F. v. Feilitzsch, S. Fichtinger, D. Fuchs, V. M. Ghete, P. Gorla, P. V. Guillaumon, D. Hauff , et al. (37 additional authors not shown)

Abstract: The current generation of cryogenic solid state detectors used in direct dark matter and CE\textnu NS searches typically reach energy thresholds of $\mathcal{O}$(10)$\,$eV for nuclear recoils. For a reliable calibration in this energy regime a method has been proposed, providing mono-energetic nuclear recoils at low energies $\sim\,$100$\,$eV$\,$-$\,$1$\,$keV. In this work we report on the observa… ▽ More The current generation of cryogenic solid state detectors used in direct dark matter and CE\textnu NS searches typically reach energy thresholds of $\mathcal{O}$(10)$\,$eV for nuclear recoils. For a reliable calibration in this energy regime a method has been proposed, providing mono-energetic nuclear recoils at low energies $\sim\,$100$\,$eV$\,$-$\,$1$\,$keV. In this work we report on the observation of a peak at (1113.6$^{+6.5}_{-6.5}$)$\,$eV in the data of an Al$_{2}$O$_{3}$ crystal in CRESST-III, which was irradiated with neutrons from an AmBe calibration source. We attribute this mono-energetic peak to the radiative capture of thermal neutrons on $^{27}$Al and the subsequent de-excitation via single $γ$-emission. We compare the measured results with the outcome of Geant4 simulations and investigate the possibility to make use of this effect for the energy calibration of Al$_{2}$O$_{3}$ detectors at low energies. We further investigate the possibility of a shift in the expected energy scale of this effect caused by the creation of defects in the target crystal. △ Less

Submitted 4 June, 2025; originally announced June 2025.

Comments: 11 pages, 8 figures

Sub-keV Electron Recoil Calibration for Macroscopic Cryogenic Calorimeters using a Novel X-ray Fluorescence Source

Authors: H. Abele, G. Angloher, B. Arnold, M. Atzori Corona, A. Bento, E. Bossio, J. Burkhart, F. Cappella, M. Cappelli, N. Casali, R. Cerulli, A. Cruciani, G. Del Castello, M. del Gallo Roccagiovine, S. Dorer, A. Erhart, M. Friedl, S. Fichtinger, V. M. Ghete, M. Giammei, C. Goupy, D. Hauff, F. Jeanneau, E. Jericha, M. Kaznacheeva , et al. (39 additional authors not shown)

Abstract: Percent-level calibration of cryogenic macro-calorimeters with energy thresholds below 100~eV are crucial for light Dark Matter (DM) searches and reactor neutrino studies based on coherent elastic neutrino-nucleus scattering (CEvNS). This paper presents a novel calibration source based on X-ray fluorescence (XRF) of light elements. It uses a $^{55}$Fe source to irradiate a two-staged target arrang… ▽ More Percent-level calibration of cryogenic macro-calorimeters with energy thresholds below 100~eV are crucial for light Dark Matter (DM) searches and reactor neutrino studies based on coherent elastic neutrino-nucleus scattering (CEvNS). This paper presents a novel calibration source based on X-ray fluorescence (XRF) of light elements. It uses a $^{55}$Fe source to irradiate a two-staged target arrangement, emitting characteristic emission lines from 677\,eV to 6.5\,keV. We demonstrate the potential of this new XRF source to calibrate a 0.75 gram CaWO$_4$ crystal of the NUCLEUS and CRAB experiments. Additionally, we introduce CryoLab, an advanced analysis tool for cryogenic detector data, featuring robust methods for data processing, calibration, and high-level analysis, implemented in MATLAB and HDF5. We also present a phenomenological model for energy resolution, which incorporates statistical contributions, systematic effects, and baseline noise, enabling a novel approach to evaluating athermal phonon collection efficiency in macro-calorimeters based on transition edge sensors (TES). △ Less

Submitted 8 September, 2025; v1 submitted 23 May, 2025; originally announced May 2025.

Journal ref: J Low Temp Phys (2025)

The CRAB facility at the TU Wien TRIGA reactor: status and related physics program

Authors: H. Abele, P. Ajello, A. Armatol, B. Arnold, J. Billard, E. Bossio, J. Burkhart, F. Cappella, N. Casali, R. Cerulli, J. Colas, J-P. Crocombette, G. del Castello, M. del Gallo Roccagiovine, S. Dorer, C. Doutre, A. Erhart, S. Fichtinger, M. Friedl, P. Garin, R. Gergen, C. Goupy, D. Hainz, D. Hauff, E. Jericha , et al. (29 additional authors not shown)

Abstract: The CRAB (Calibrated nuclear Recoils for Accurate Bolometry) project aims to precisely characterize the response of cryogenic detectors to sub-keV nuclear recoils of direct interest for coherent neutrino-nucleus scattering and dark matter search experiments. The CRAB method relies on the radiative capture of thermal neutrons in the target detector, resulting in a nuclear recoil with a well-defined… ▽ More The CRAB (Calibrated nuclear Recoils for Accurate Bolometry) project aims to precisely characterize the response of cryogenic detectors to sub-keV nuclear recoils of direct interest for coherent neutrino-nucleus scattering and dark matter search experiments. The CRAB method relies on the radiative capture of thermal neutrons in the target detector, resulting in a nuclear recoil with a well-defined energy. We present a new experimental setup installed at the TRIGA Mark-II reactor at Atominstitut (Vienna), providing a low intensity beam of thermal neutrons sent to the target cryogenic detector mounted inside a wet dilution refrigerator Kelvinox 100. A crown of BaF$_2$ detectors installed outside the dewar enables coincident detection of the high-energy $γ$ escaping the target crystal after neutron capture. After the presentation of all components of the setup we report the analysis of first commissioning data with a CaWO$_4$ detector of the \NUCLEUS experiment. They show stable operation of the cryostat and detectors on a week-scale. Due to an energy resolution currently limited to 20 eV we use neutron beam induced events at high energy, in the 10 to 100 keV range, to demonstrate the excellent agreement between the data and simulation and the accurate understanding of external background. Thanks to these data we also propose an updated decay scheme of the low-lying excited states of $^{187}$W. Finally, we present the first evidence of neutron-capture induced coincidences between $γ$-detectors and a cryogenic detector. These promising results pave the way for an extensive physics program with various detector materials, like CaWO$_4$, Al$_2$O$_3$, Ge and Si. △ Less

Submitted 21 May, 2025; originally announced May 2025.

Comments: 27 pages, 23 figures

The CRESST experiment: towards the next-generation of sub-GeV direct dark matter detection

Authors: G. Angloher, S. Banik, A. Bento, A. Bertolini, R. Breier, C. Bucci, J. Burkhart, L. Canonica, E. R. Cipelli, S. Di Lorenzo, J. Dohm, F. Dominsky, L. Einfalt, A. Erb, E. Fascione, F. v. Feilitzsch, S. Fichtinger, D. Fuchs, V. M. Ghete, P. Gorla, P. V. Guillaumon, D. Hauff, M. Jeskovsky, J. Jochum, M. Kaznacheeva , et al. (32 additional authors not shown)

Abstract: Direct detection experiments have established the most stringent constraints on potential interactions between particle candidates for relic, thermal dark matter and Standard Model particles. To surpass current exclusion limits a new generation of experiments is being developed. The upcoming upgrade of the CRESST experiment will incorporate $\mathcal{O}$(100) detectors with different masses rangin… ▽ More Direct detection experiments have established the most stringent constraints on potential interactions between particle candidates for relic, thermal dark matter and Standard Model particles. To surpass current exclusion limits a new generation of experiments is being developed. The upcoming upgrade of the CRESST experiment will incorporate $\mathcal{O}$(100) detectors with different masses ranging from $\sim$2g to $\sim$24g, aiming to achieve unprecedented sensitivity to sub-GeV dark matter particles with a focus on spin-independent dark matter-nucleus scattering. This paper presents a comprehensive analysis of the planned upgrade, detailed experimental strategies, anticipated challenges, and projected sensitivities. Approaches to address and mitigate low-energy excess backgrounds $-$ a key limitation in previous and current sub-GeV dark matter searches $-$ are also discussed. In addition, a long-term roadmap for the next decade is outlined, including other potential scientific applications. △ Less

Submitted 2 May, 2025; originally announced May 2025.

Comments: 12 pages, 7 figures, submitted to Nature (The Direct Detection of Dark Matter in the Underground Laboratory Collection - Communications Physics)

Decoupling Pulse Tube Vibrations from a Dry Dilution Refrigerator at milli-Kelvin Temperatures

Authors: The NUCLEUS collaboration, A. Wex, J. Rothe, L. Peters, H. Abele, G. Angloher, B. Arnold, M. Atzori Corona, A. Bento, E. Bossio, J. Burkhart, L. Canonica, F. Cappella, M. Cappelli, N. Casali, R. Cerulli, A. Cruciani, G. Del Castello, M. del Gallo Roccagiovine, A. Doblhammer, S. Dorer, A. Erhart, M. Friedl, S. Fichtinger, A. Garai , et al. (42 additional authors not shown)

Abstract: With the rising adoption of dry dilution refrigerators across scientific and industrial domains, there has been a pressing demand for highly efficient vibration decoupling systems capable of operation at cryogenic temperatures in order to achieve the low vibration levels required for operation of sensitive equipment like cryogenic detectors or quantum devices. As part of the NUCLEUS experiment, a… ▽ More With the rising adoption of dry dilution refrigerators across scientific and industrial domains, there has been a pressing demand for highly efficient vibration decoupling systems capable of operation at cryogenic temperatures in order to achieve the low vibration levels required for operation of sensitive equipment like cryogenic detectors or quantum devices. As part of the NUCLEUS experiment, a cryogenic spring pendulum has been engineered to effectively isolate pulse tube vibrations by establishing an autonomous frame of reference for the experimental volume, while sustaining temperatures below 10 mK. Attaining attenuation of up to two orders of magnitude within the region of interest of the NUCLEUS cryogenic detectors, we achieved displacement RMS values in the order of 1 nm in the axial direction and 100 pm radially, thereby reducing vibrations below typical environmental levels. Our successful detector operation across multiple cooldown cycles demonstrated negligible sensitivity to pulse tube induced vibrations, culminating in the achievement of an ultra-low $(6.22 \pm 0.07)$ eV baseline resolution on a gram-scale CaWO$_4$ cryogenic calorimeter during continuous pulse tube operation over the course of several weeks. △ Less

Submitted 7 April, 2025; v1 submitted 8 January, 2025; originally announced January 2025.

Prevention of resistive wall tearing mode major disruptions with feedback

Authors: H. R. Strauss

Abstract: Resistive wall tearing modes (RWTM) can cause major disruptions. A signature of RWTMs is that the rational surface is sufficiently close to the wall. For $(m,n) = (2,1)$ modes, at normalized minor radius $ρ= 0.75$, the value of $q$ is $q_{75} < 2.$ This is confirmed in simulations and theory and in a DIII-D locked mode disruption database. The $q_{75} < 2$ criterion is valid at high $β$ as well as… ▽ More Resistive wall tearing modes (RWTM) can cause major disruptions. A signature of RWTMs is that the rational surface is sufficiently close to the wall. For $(m,n) = (2,1)$ modes, at normalized minor radius $ρ= 0.75$, the value of $q$ is $q_{75} < 2.$ This is confirmed in simulations and theory and in a DIII-D locked mode disruption database. The $q_{75} < 2$ criterion is valid at high $β$ as well as at low $β.$ A very important feature of RWTMs is that they produce major disruptions only when the $q_{75} < 2$ criterion is satisfied. If it is not satisfied, or if the wall is ideally conducting, then the mode does not produce a major disruption, although it can produce a minor disruption. Feedback, or rotation of the mode at the wall by complex feedback, can emulate an ideal wall, preventing major disruptions. The $q_{75}$ criterion is analyzed in a linear simulations, and a simple geometric model is given. △ Less

Submitted 28 November, 2024; v1 submitted 20 November, 2024; originally announced November 2024.

The DECam Ecliptic Exploration Project (DEEP). VII. The Strengths of Three Superfast Rotating Main-belt Asteroids from a Preliminary Search of DEEP Data

Authors: Ryder Strauss, Andrew McNeill, David E. Trilling, Francisco Valdes, Pedro H. Bernardinell, Cesar Fuentes, David W. Gerdes, Matthew J. Holman, Mario Juric, Hsing Wen Lin, Larissa Markwardt, Michael Mommert, Kevin J. Napier, William J. Oldroyd, Matthew J. Payne, Andrew S. Rivkin, Hilke E. Schlichting, Scott S. Sheppard, Hayden Smotherman, Chadwick A Trujillo, Fred C. Adams, Colin Orion Chandler

Abstract: Superfast rotators (SFRs) are small solar system objects that rotate faster than generally possible for a cohesionless rubble pile. Their rotational characteristics allow us to make inferences about their interior structure and composition. Here, we present the methods and results from a preliminary search for SFRs in the DECam Ecliptic Exploration Project (DEEP) data set. We find three SFRs from… ▽ More Superfast rotators (SFRs) are small solar system objects that rotate faster than generally possible for a cohesionless rubble pile. Their rotational characteristics allow us to make inferences about their interior structure and composition. Here, we present the methods and results from a preliminary search for SFRs in the DECam Ecliptic Exploration Project (DEEP) data set. We find three SFRs from a sample of 686 main-belt asteroids, implying an occurrence rate of 0.4 -0.3/+0.1 percent - a higher incidence rate than has been measured by previous studies. We suggest that this high occurrence rate is due to the small sub-kilometer size regime to which DEEP has access: the objects searched here were as small as 500 m. We compute the minimum required cohesive strength for each of these SFRs and discuss the implications of these strengths in the context of likely evolution mechanisms. We find that all three of these SFRs require strengths that are more than that of weak regolith but consistent with many cohesive asteroid strengths reported in the literature. Across the full DEEP data set, we have identified ~70,000 Main-Belt Asteroids and expect ~300 SFRs - a result that will be assessed in a future paper. △ Less

Submitted 1 October, 2024; originally announced October 2024.

Journal ref: The Astronomical Journal, Volume 168, Number 4 (2024)

Infrared Colors of Small Serendipitously-Found Asteroids in the UKIRT Hemisphere Survey

Authors: Samantha G. Morrison, Ryder H. Strauss, David E. Trilling, Andy J. López-Oquendo, Justice Bruursema, Frederick J. Vrba

Abstract: The UKIRT Hemisphere Survey covers the northern sky in the infrared from 0-60 degrees declination. Current data releases include both J and K bands, with H-band data forthcoming. Here we present a novel pipeline to recover asteroids from this survey data. We recover 26,138 reliable observations, corresponding to 23,399 unique asteroids, from these public data. We measure J-K colors for 601 asteroi… ▽ More The UKIRT Hemisphere Survey covers the northern sky in the infrared from 0-60 degrees declination. Current data releases include both J and K bands, with H-band data forthcoming. Here we present a novel pipeline to recover asteroids from this survey data. We recover 26,138 reliable observations, corresponding to 23,399 unique asteroids, from these public data. We measure J-K colors for 601 asteroids. Our survey extends about two magnitudes deeper than 2MASS. We find that our small inner main belt objects are less red than larger inner belt objects, perhaps because smaller asteroids are collisionally younger, with surfaces that have been less affected by space weathering. In the middle and outer main belt, we find our small asteroids to be redder than larger objects in their same orbits, possibly due to observational bias or a disproportionate population of very red objects among these smaller asteroids. Future work on this project includes extracting moving object measurements from H and Y band data when it becomes available. △ Less

Submitted 24 July, 2024; originally announced July 2024.

Comments: 15 pages, 10 figures

A detailed survey of the parallel mean free path of solar energetic particle protons and electrons

Authors: J. T. Lang, R. D. Strauss, N. E. Engelbrecht, J. P. van den Berg, N. Dresing, D. Ruffolo, R. Bandyopadhyay

Abstract: In this work, more than a dozen solar energetic particle (SEP) events are identified where the source region is magnetically well-connected to at least one spacecraft at 1~au. The observed intensity-time profiles, for all available proton and electron energy channels, are compared to results computed using a numerical 1D SEP transport model in order to derive the parallel mean free paths (pMFPs) a… ▽ More In this work, more than a dozen solar energetic particle (SEP) events are identified where the source region is magnetically well-connected to at least one spacecraft at 1~au. The observed intensity-time profiles, for all available proton and electron energy channels, are compared to results computed using a numerical 1D SEP transport model in order to derive the parallel mean free paths (pMFPs) as a function of energy (or rigidity) at 1~au. These inversion results are then compared to theoretical estimates of the pMFP, using observed turbulence quantities with observationally-motivated variations as input. For protons, a very good comparison between inversion and theoretical results is obtained. It is shown that the observed inter-event variations in the inversion pMFP values can be explained by natural variations in the background turbulence values. For electrons, there is relatively good agreement with pMFPs derived assuming the damping model of dynamical turbulence, although the theoretical values are extremely sensitive to the details of the turbulence dissipation range which themselves display a high level of variation. △ Less

Submitted 9 June, 2024; originally announced June 2024.

Comments: Accepted to ApJ

First observation of single photons in a CRESST detector and new dark matter exclusion limits

Authors: CRESST Collaboration, G. Angloher, S. Banik, G. Benato, A. Bento, A. Bertolini, R. Breier, C. Bucci, J. Burkhart, L. Canonica, A. D'Addabbo, S. Di Lorenzo, L. Einfalt, A. Erb, F. v. Feilitzsch, S. Fichtinger, D. Fuchs, A. Garai, V. M. Ghete, P. Gorla, P. V. Guillaumon, S. Gupta, D. Hauff, M. Ješkovský, J. Jochum , et al. (34 additional authors not shown)

Abstract: The main goal of the CRESST-III experiment is the direct detection of dark matter particles via their scattering off target nuclei in cryogenic detectors. In this work we present the results of a Silicon-On-Sapphire (SOS) detector with a mass of 0.6$\,$g and an energy threshold of (6.7$\, \pm \,$0.2)$\,$eV with a baseline energy resolution of (1.0$\, \pm \,$0.2)$\,$eV. This allowed for a calibrati… ▽ More The main goal of the CRESST-III experiment is the direct detection of dark matter particles via their scattering off target nuclei in cryogenic detectors. In this work we present the results of a Silicon-On-Sapphire (SOS) detector with a mass of 0.6$\,$g and an energy threshold of (6.7$\, \pm \,$0.2)$\,$eV with a baseline energy resolution of (1.0$\, \pm \,$0.2)$\,$eV. This allowed for a calibration via the detection of single luminescence photons in the eV-range, which could be observed in CRESST for the first time. We present new exclusion limits on the spin-independent and spin-dependent dark matter-nucleon cross section that extend to dark matter particle masses of less than 100$\,$MeV/c$^{2}$. △ Less

Submitted 10 May, 2024; originally announced May 2024.

Comments: 10 pages, 8 figures

Jupiter Co-Orbital Comet P/2023 V6 (PANSTARRS): Orbital History and Modern Activity State

Authors: Theodore Kareta, John W. Noonan, Kathryn Volk, Ryder H. Strauss, David Trilling

Abstract: The discovery of the transient Jupiter co-orbital comet P/2019 LD2 (ATLAS) drew significant interest. Not only will LD2 transition between being a Centaur and a Jupiter Family Comet (JFC) in 2063, the first time this process can be observed as it happens, it is also very active for its large heliocentric distance. We present observations and orbital integrations of the newly discovered transient J… ▽ More The discovery of the transient Jupiter co-orbital comet P/2019 LD2 (ATLAS) drew significant interest. Not only will LD2 transition between being a Centaur and a Jupiter Family Comet (JFC) in 2063, the first time this process can be observed as it happens, it is also very active for its large heliocentric distance. We present observations and orbital integrations of the newly discovered transient Jupiter co-orbital comet P/2023 V6 (PANSTARRS), the second such object known. Despite similar modern orbits, V6 is significantly (15 times) less active than LD2 and most JFCs as determined via Afrho measurements at the same heliocentric distance. We find V6 is co-orbital between 2020 and 2044, twice the duration of LD2, but it will not become a JFC soon. We interpret these differences in activity as evolutionary, with V6 having lost a significant fraction of its near-surface ice compared to LD2 by previously being warmer. While V6's pre-encounter orbit was somewhat warmer than LD2's, future thermal modeling will be needed to understand if this can explain their differences or if a more significant difference further into the past is required. This is more evidence that LD2 is a pristine and ice-rich object, and thus it may display very strong activity when it becomes a JFC. We sue the differences between V6 and LD2 to discuss the interpretation of cometary activity at large heliocentric distances as well as the small end of the crater record of the Galilean Satellites. Continuing observations of both objects are highly encouraged. △ Less

Submitted 12 April, 2024; originally announced April 2024.

Comments: Accepted for publication in the Astrophysical Journal: Letters on April 11, 2024. Four figures, fifteen pages

DoubleTES detectors to investigate the CRESST low energy background: results from above-ground prototypes

Authors: G. Angloher, S. Banik, G. Benato, A. Bento, A. Bertolini, R. Breier, C. Bucci, J. Burkhart, L. Canonica, A. D'Addabbo, S. Di Lorenzo, L. Einfalt, A. Erb, F. v. Feilitzsch, S. Fichtinger, D. Fuchs, A. Garai, V. M. Ghete, P. Gorla, P. V. Guillaumon, S. Gupta, D. Hauff, M. Ješkovský, J. Jochum, M. Kaznacheeva , et al. (33 additional authors not shown)

Abstract: In recent times, the sensitivity of low-mass direct dark matter searches has been limited by unknown low energy backgrounds close to the energy threshold of the experiments known as the low energy excess (LEE). The CRESST experiment utilises advanced cryogenic detectors constructed with different types of crystals equipped with Transition Edge Sensors (TESs) to measure signals of nuclear recoils i… ▽ More In recent times, the sensitivity of low-mass direct dark matter searches has been limited by unknown low energy backgrounds close to the energy threshold of the experiments known as the low energy excess (LEE). The CRESST experiment utilises advanced cryogenic detectors constructed with different types of crystals equipped with Transition Edge Sensors (TESs) to measure signals of nuclear recoils induced by the scattering of dark matter particles in the detector. In CRESST, this low energy background manifests itself as a steeply rising population of events below 200 eV. A novel detector design named doubleTES using two identical TESs on the target crystal was studied to investigate the hypothesis that the events are sensor-related. We present the first results from two such modules, demonstrating their ability to differentiate between events originating from the crystal's bulk and those occurring in the sensor or in its close proximity. △ Less

Submitted 3 April, 2024; originally announced April 2024.

Comments: 10 pages, 13 figures

A likelihood framework for cryogenic scintillating calorimeters used in the CRESST dark matter search

Authors: CRESST Collaboration, G. Angloher, S. Banik, G. Benato, A. Bento, A. Bertolini, R. Breier, C. Bucci, J. Burkhart, L. Canonica, A. D'Addabbo, S. Di Lorenzo, L. Einfalt, A. Erb, F. v. Feilitzsch, S. Fichtinger, D. Fuchs, A. Garai, V. M. Ghete, P. Gorla, P. V. Guillaumon, S. Gupta, D. Hauff, M. Ješkovský, J. Jochum , et al. (35 additional authors not shown)

Abstract: Cryogenic scintillating calorimeters are ultrasensitive particle detectors for rare event searches, particularly for the search for dark matter and the measurement of neutrino properties. These detectors are made from scintillating target crystals generating two signals for each particle interaction. The phonon (heat) signal precisely measures the deposited energy independent of the type of intera… ▽ More Cryogenic scintillating calorimeters are ultrasensitive particle detectors for rare event searches, particularly for the search for dark matter and the measurement of neutrino properties. These detectors are made from scintillating target crystals generating two signals for each particle interaction. The phonon (heat) signal precisely measures the deposited energy independent of the type of interacting particle. The scintillation light signal yields particle discrimination on an event-by-event basis. This paper presents a likelihood framework modeling backgrounds and a potential dark matter signal in the two-dimensional plane spanned by phonon and scintillation light energies. We apply the framework to data from CaWO$_4$-based detectors operated in the CRESST dark matter search. For the first time, a single likelihood framework is used in CRESST to model the data and extract results on dark matter in one step by using a profile likelihood ratio test. Our framework simultaneously fits (neutron) calibration data and physics (background) data and allows combining data from multiple detectors. Although tailored to CaWO$_4$-targets and the CRESST experiment, the framework can easily be expanded to other materials and experiments using scintillating cryogenic calorimeters for dark matter search and neutrino physics. △ Less

Submitted 16 September, 2024; v1 submitted 6 March, 2024; originally announced March 2024.

Comments: 18 pages, 11 figures, additional figures and data in ancillary files (on arXiv or at journal reference)

Journal ref: Eur. Phys. J. C 84, 922 (2024)

Exoplanet Analog Observations of Earth from Galileo Disk-integrated Photometry

Authors: Ryder H. Strauss, Tyler D. Robinson, David E. Trilling, Ryan Cummings, Christopher J. Smith

Abstract: The Galileo spacecraft had distant encounters with Earth in 1990 and 1992. Limited Solid State Imager (SSI) data acquired during these encounters has been previously presented, but the majority of the data from these Earth flybys have not been presented in the literature. Observations of Earth taken from afar are both rare and directly relevant to the development of any future exo-Earth direct ima… ▽ More The Galileo spacecraft had distant encounters with Earth in 1990 and 1992. Limited Solid State Imager (SSI) data acquired during these encounters has been previously presented, but the majority of the data from these Earth flybys have not been presented in the literature. Observations of Earth taken from afar are both rare and directly relevant to the development of any future exo-Earth direct imaging mission. Here we present a pipeline that vets, calibrates, and measures the disk-integrated brightness of the Earth, in multiple filters, from the complete SSI data sets from both the 1990 and 1992 Galileo flybys. The result is over 1500 usable photometric measurements for Earth as an analog for an exoplanet. The 1990 data set includes full rotational lightcurves in six bandpasses spanning the optical range. The 1992 data set is more limited, with lightcurves only spanning 14 hr. Time-averaged photometry for both encounters is presented while variability and color are discussed relative to findings from NASA's EPOXI mission (which also provided photometric lighturves for Earth). The new Galileo/SSI data are used to further validate the Virtual Planetary Laboratory 3D spectral Earth model, which often serves as a stand-in for true disk-integrated observations of our planet. The revived Galileo/SSI data for Earth is a testament to the ability of NASA's Planetary Data System to maintain data over decades-long timescales. The disk-integrated products derived from these data add to a very short list of calibrated and published whole-disk observations of the Pale Blue Dot. △ Less

Submitted 1 February, 2024; originally announced February 2024.

Journal ref: AJ 167 87 (2024)

Resistive Wall Tearing Mode Disruptions

Authors: H. R. Strauss, B. E. Chapman, B. C. Lyons

Abstract: This paper deals with resistive wall tearing mode (RWTM) disruptions. RWTMs are closely related to resistive wall modes (RWMs). The nonlinear behavior of these modes is strongly dependent on the resistive wall outside the plasma. A conducting wall is highly mitigating for RWTM disruptions. The consequence for ITER, which has a highly conducting wall, is that the thermal quench (TQ) time could be m… ▽ More This paper deals with resistive wall tearing mode (RWTM) disruptions. RWTMs are closely related to resistive wall modes (RWMs). The nonlinear behavior of these modes is strongly dependent on the resistive wall outside the plasma. A conducting wall is highly mitigating for RWTM disruptions. The consequence for ITER, which has a highly conducting wall, is that the thermal quench (TQ) time could be much longer than previously conjectured. Active feedback stabilization is another possible way to mitigate or prevent RWTM disruptions. Simulations of disruptions are reviewed for DIII-D and MST. MST has a longer resistive wall time than ITER, and disruptions are not observed experimentally when MST is operated as a standard tokamak. Simulations indicate that the RWTM disruption time scale is longer than the experimental shot time. In general, edge cooling by tearing mode island overlap or by impurity radiation causes contraction of the current profile, which destabilizes RWTMs. The equilibria studied here have a q = 2 rational surface close to the edge of the plasma, and low edge current density. A sequence of low edge current model equilibria hasmajor disruptions only for a resistive, not ideal, wall, and approximately edge q < 3. This is consistent with typical regimes of tokamak disruption avoidance, suggesting that typical tokamak disruptions could be RWTMs. △ Less

Submitted 13 January, 2024; originally announced January 2024.

Jovian electrons in the inner heliosphere: Opportunities for Multi-spacecraft Observations and Modeling

Authors: R. D. Strauss, N. Dresing, N. E. Engelbrecht, J. G. Mitchell, P. Kühl, S. Jensen, S. Fleth, B. Sánchez-Cano, A. Posner, J. S Rankin, C. O. Lee, J. P. van den Berg, S. E. S. Ferreira, B. Heber

Abstract: In this paper we explore the idea of using multi-spacecraft observations of Jovian electrons to measure the 3D distribution of these particles in the inner heliosphere. We present simulations of Jovian electron intensities along selected spacecraft trajectories for 2021 and compare these, admittedly qualitatively, to these measurements. Using the data-model comparison we emphasize how such a study… ▽ More In this paper we explore the idea of using multi-spacecraft observations of Jovian electrons to measure the 3D distribution of these particles in the inner heliosphere. We present simulations of Jovian electron intensities along selected spacecraft trajectories for 2021 and compare these, admittedly qualitatively, to these measurements. Using the data-model comparison we emphasize how such a study can be used to constrain the transport parameters in the inner heliosphere, and how this can lead to additional insight into energetic particle transport. Model results are also shown along the expected trajectories of selected spacecraft, including the off-ecliptic phase of the Solar Orbiter mission from 2025 onward. Lastly, we revisit the use of historical data and discuss upcoming missions that may contribute to Jovian electron measurements. △ Less

Submitted 6 December, 2023; originally announced January 2024.

Comments: Accepted for publication in ApJ

Optimal operation of cryogenic calorimeters through deep reinforcement learning

Authors: G. Angloher, S. Banik, G. Benato, A. Bento, A. Bertolini, R. Breier, C. Bucci, J. Burkhart, L. Canonica, A. D'Addabbo, S. Di Lorenzo, L. Einfalt, A. Erb, F. v. Feilitzsch, S. Fichtinger, D. Fuchs, A. Garai, V. M. Ghete, P. Gorla, P. V. Guillaumon, S. Gupta, D. Hauff, M. Ješkovský, J. Jochum, M. Kaznacheeva , et al. (37 additional authors not shown)

Abstract: Cryogenic phonon detectors with transition-edge sensors achieve the best sensitivity to light dark matter-nucleus scattering in current direct detection dark matter searches. In such devices, the temperature of the thermometer and the bias current in its readout circuit need careful optimization to achieve optimal detector performance. This task is not trivial and is typically done manually by an… ▽ More Cryogenic phonon detectors with transition-edge sensors achieve the best sensitivity to light dark matter-nucleus scattering in current direct detection dark matter searches. In such devices, the temperature of the thermometer and the bias current in its readout circuit need careful optimization to achieve optimal detector performance. This task is not trivial and is typically done manually by an expert. In our work, we automated the procedure with reinforcement learning in two settings. First, we trained on a simulation of the response of three CRESST detectors used as a virtual reinforcement learning environment. Second, we trained live on the same detectors operated in the CRESST underground setup. In both cases, we were able to optimize a standard detector as fast and with comparable results as human experts. Our method enables the tuning of large-scale cryogenic detector setups with minimal manual interventions. △ Less

Submitted 25 November, 2023; originally announced November 2023.

Comments: 23 pages, 14 figures, 2 tables

Journal ref: Comput Softw Big Sci 8, 10 (2024)

Detector development for the CRESST experiment

Authors: G. Angloher, S. Banik, G. Benato, A. Bento, A. Bertolini, R. Breier, C. Bucci, J. Burkhart, L. Canonica, A. D'Addabbo, S. Di Lorenzo, L. Einfalt, A. Erb, F. v. Feilitzsch, S. Fichtinger, D. Fuchs, A. Garai, V. M. Ghete, P. Gorla, P. V. Guillaumon, S. Gupta, D. Hauff, M. Ješkovský, J. Jochum, M. Kaznacheeva , et al. (33 additional authors not shown)

Abstract: Recently low-mass dark matter direct searches have been hindered by a low energy background, drastically reducing the physics reach of the experiments. In the CRESST-III experiment, this signal is characterised by a significant increase of events below 200 eV. As the origin of this background is still unknown, it became necessary to develop new detector designs to reach a better understanding of t… ▽ More Recently low-mass dark matter direct searches have been hindered by a low energy background, drastically reducing the physics reach of the experiments. In the CRESST-III experiment, this signal is characterised by a significant increase of events below 200 eV. As the origin of this background is still unknown, it became necessary to develop new detector designs to reach a better understanding of the observations. Within the CRESST collaboration, three new different detector layouts have been developed and they are presented in this contribution. △ Less

Submitted 13 November, 2023; originally announced November 2023.

Comments: 8 pages, 4 figures

17O enrichment of CaWO4 crystals for spin-dependent DM search

Authors: Angelina Kinast, Andreas Erb, Stefan Schönert, Raimund Strauss, Jürgen Haase

Abstract: For many years, various experiments have attempted to shed light on the nature of dark matter (DM). This work investigates the possibility of using CaWO4 crystals for the direct search of spin-dependent DM interactions using the isotope 17O with a nuclear spin of 5/2. Due to the low natural abundance of 0.038%, an enrichment of the CaWO4 crystals with 17O is developed during the crystal production… ▽ More For many years, various experiments have attempted to shed light on the nature of dark matter (DM). This work investigates the possibility of using CaWO4 crystals for the direct search of spin-dependent DM interactions using the isotope 17O with a nuclear spin of 5/2. Due to the low natural abundance of 0.038%, an enrichment of the CaWO4 crystals with 17O is developed during the crystal production process at the Technical University of Munich. Three CaWO4 crystals were enriched, and their 17O content was measured by nuclear magnetic resonance spectroscopy at the University of Leipzig. This paper presents the concept and first results of the 17O enrichment and discusses the possibility of using enriched crystals to increase the sensitivity for the spin-dependent DM search with CRESST. △ Less

Submitted 6 November, 2023; originally announced November 2023.

Comments: XVIII International Conference on Topics in Astroparticle and Underground Physics, TAUP2023, submitted to Proceedings of Science

The DECam Ecliptic Exploration Project (DEEP) II. Observational Strategy and Design

Authors: Chadwick A. Trujillo, Cesar Fuentes, David W. Gerdes, Larissa Markwardt, Scott S. Sheppard, Ryder Strauss, Colin Orion Chandler, William J. Oldroyd, David E. Trilling, Hsing Wen Lin, Fred C. Adams, Pedro H. Bernardinelli, Matthew J. Holman, Mario Juric, Andrew McNeill, Michael Mommert, Kevin J. Napier, Matthew J. Payne, Darin Ragozzine, Andrew S. Rivkin, Hilke Schlichting, Hayden Smotherman

Abstract: We present the DECam Ecliptic Exploration Project (DEEP) survey strategy including observing cadence for orbit determination, exposure times, field pointings and filter choices. The overall goal of the survey is to discover and characterize the orbits of a few thousand Trans-Neptunian Objects (TNOs) using the Dark Energy Camera (DECam) on the Cerro Tololo Inter-American Observatory (CTIO) Blanco 4… ▽ More We present the DECam Ecliptic Exploration Project (DEEP) survey strategy including observing cadence for orbit determination, exposure times, field pointings and filter choices. The overall goal of the survey is to discover and characterize the orbits of a few thousand Trans-Neptunian Objects (TNOs) using the Dark Energy Camera (DECam) on the Cerro Tololo Inter-American Observatory (CTIO) Blanco 4 meter telescope. The experiment is designed to collect a very deep series of exposures totaling a few hours on sky for each of several 2.7 square degree DECam fields-of-view to achieve a magnitude of about 26.2 using a wide VR filter which encompasses both the V and R bandpasses. In the first year, several nights were combined to achieve a sky area of about 34 square degrees. In subsequent years, the fields have been re-visited to allow TNOs to be tracked for orbit determination. When complete, DEEP will be the largest survey of the outer solar system ever undertaken in terms of newly discovered object numbers, and the most prolific at producing multi-year orbital information for the population of minor planets beyond Neptune at 30 au. △ Less

Submitted 30 October, 2023; originally announced October 2023.

Comments: 29 pages, 4 figures and 4 tables

A Plastic Scintillation Muon Veto for Sub-Kelvin Temperatures

Authors: A. Erhart, V. Wagner, A. Wex, C. Goupy, D. Lhuillier, E. Namuth, C. Nones, R. Rogly, V. Savu, M. Schwarz, R. Strauss, M. Vivier, H. Abele, G. Angloher, A. Bento, J. Burkhart, L. Canonica, F. Cappella, N. Casali, R. Cerulli, A. Cruciani, G. del Castello, M. del Gallo Roccagiovine, A. Doblhammer, S. Dorer , et al. (37 additional authors not shown)

Abstract: Rare-event search experiments located on-surface, such as short-baseline reactor neutrino experiments, are often limited by muon-induced background events. Highly efficient muon vetos are essential to reduce the detector background and to reach the sensitivity goals. We demonstrate the feasibility of deploying organic plastic scintillators at sub-Kelvin temperatures. For the NUCLEUS experiment, we… ▽ More Rare-event search experiments located on-surface, such as short-baseline reactor neutrino experiments, are often limited by muon-induced background events. Highly efficient muon vetos are essential to reduce the detector background and to reach the sensitivity goals. We demonstrate the feasibility of deploying organic plastic scintillators at sub-Kelvin temperatures. For the NUCLEUS experiment, we developed a cryogenic muon veto equipped with wavelength shifting fibers and a silicon photo multiplier operating inside a dilution refrigerator. The achievable compactness of cryostat-internal integration is a key factor in keeping the muon rate to a minimum while maximizing coverage. The thermal and light output properties of a plastic scintillation detector were examined. We report first data on the thermal conductivity and heat capacity of the polystyrene-based scintillator UPS-923A over a wide range of temperatures extending below one Kelvin. The light output was measured down to 0.8K and observed to increase by a factor of 1.61$\pm$0.05 compared to 300K. The development of an organic plastic scintillation muon veto operating in sub-Kelvin temperature environments opens new perspectives for rare-event searches with cryogenic detectors at sites lacking substantial overburden. △ Less

Submitted 12 October, 2023; originally announced October 2023.

Light Dark Matter Search Using a Diamond Cryogenic Detector

Authors: CRESST Collaboration, G. Angloher, S. Banik, G. Benato, A. Bento, A. Bertolini, R. Breier, C. Bucci, J. Burkhart, L. Canonica, A. D'Addabbo, S. Di Lorenzo, L. Einfalt, A. Erb, F. v. Feilitzsch, S. Fichtinger, D. Fuchs, A. Garai, V. M. Ghete, P. Gorla, P. V. Guillaumon, S. Gupta, D. Hauff, M. Ješkovský, J. Jochum , et al. (34 additional authors not shown)

Abstract: Diamond operated as a cryogenic calorimeter is an excellent target for direct detection of low-mass dark matter candidates. Following the realization of the first low-threshold cryogenic detector that uses diamond as absorber for astroparticle physics applications, we now present the resulting exclusion limits on the elastic spin-independent interaction cross-section of dark matter with diamond. W… ▽ More Diamond operated as a cryogenic calorimeter is an excellent target for direct detection of low-mass dark matter candidates. Following the realization of the first low-threshold cryogenic detector that uses diamond as absorber for astroparticle physics applications, we now present the resulting exclusion limits on the elastic spin-independent interaction cross-section of dark matter with diamond. We measured two 0.175 g CVD (Chemical Vapor Deposition) diamond samples, each instrumented with a W-TES. Thanks to the energy threshold of just 16.8 eV of one of the two detectors, we set exclusion limits on the elastic spin-independent interaction of dark matter particles with carbon nuclei down to dark matter masses as low as 0.122 GeV/c2. This work shows the scientific potential of cryogenic detectors made from diamond and lays the foundation for the use of this material as target for direct detection dark matter experiments. △ Less

Submitted 9 October, 2023; originally announced October 2023.

Comments: 6 pages, 6 figures

The DECam Ecliptic Exploration Project (DEEP) VI: first multi-year observations of trans-Neptunian objects

Authors: Hayden Smotherman, Pedro H. Bernardinelli, Stephen K. N. Portillo, Andrew J. Connolly, J. Bryce Kalmbach, Steven Stetzler, Mario Juric, Dino Bektesvic, Zachary Langford, Fred C. Adams, William J. Oldroyd, Matthew J. Holman, Colin Orion Chandler, Cesar Fuentes, David W. Gerdes, Hsing Wen Lin, Larissa Markwardt, Andrew McNeill, Michael Mommert, Kevin J. Napier, Matthew J. Payne, Darin Ragozzine, Andrew S. Rivkin, Hilke Schlichting, Scott S. Sheppard , et al. (3 additional authors not shown)

Abstract: We present the first set of trans-Neptunian objects (TNOs) observed on multiple nights in data taken from the DECam Ecliptic Exploration Project (DEEP). Of these 110 TNOs, 105 do not coincide with previously known TNOs and appear to be new discoveries. Each individual detection for our objects resulted from a digital tracking search at TNO rates of motion, using two to four hour exposure sets, and… ▽ More We present the first set of trans-Neptunian objects (TNOs) observed on multiple nights in data taken from the DECam Ecliptic Exploration Project (DEEP). Of these 110 TNOs, 105 do not coincide with previously known TNOs and appear to be new discoveries. Each individual detection for our objects resulted from a digital tracking search at TNO rates of motion, using two to four hour exposure sets, and the detections were subsequently linked across multiple observing seasons. This procedure allows us to find objects with magnitudes $m_{VR} \approx 26$. The object discovery processing also included a comprehensive population of objects injected into the images, with a recovery and linking rate of at least $94\%$. The final orbits were obtained using a specialized orbit fitting procedure that accounts for the positional errors derived from the digital tracking procedure. Our results include robust orbits and magnitudes for classical TNOs with absolute magnitudes $H \sim 10$, as well as a dynamically detached object found at 76 au (semi-major axis $a\approx 77 \, \mathrm{au}$). We find a disagreement between our population of classical TNOs and the CFEPS-L7 three component model for the Kuiper belt. △ Less

Submitted 5 October, 2023; originally announced October 2023.

Comments: Accepted to AJ, companion paper do DEEP III. Objects will be released in the journal version (or contacting the authors)

The DECam Ecliptic Exploration Project (DEEP) III: Survey characterization and simulation methods

Authors: Pedro H. Bernardinelli, Hayden Smotherman, Zachary Langford, Stephen K. N. Portillo, Andrew J. Connolly, J. Bryce Kalmbach, Steven Stetzler, Mario Juric, William J. Oldroyd, Hsing Wen Lin, Fred C. Adams, Colin Orion Chandler, Cesar Fuentes, David W. Gerdes, Matthew J. Holman, Larissa Markwardt, Andrew McNeill, Michael Mommert, Kevin J. Napier, Matthew J. Payne, Darin Ragozzine, Andrew S. Rivkin, Hilke Schlichting, Scott S. Sheppard, Ryder Strauss , et al. (2 additional authors not shown)

Abstract: We present a detailed study of the observational biases of the DECam Ecliptic Exploration Project's (DEEP) B1 data release and survey simulation software that enables direct statistical comparisons between models and our data. We inject a synthetic population of objects into the images, and then subsequently recover them in the same processing as our real detections. This enables us to characteriz… ▽ More We present a detailed study of the observational biases of the DECam Ecliptic Exploration Project's (DEEP) B1 data release and survey simulation software that enables direct statistical comparisons between models and our data. We inject a synthetic population of objects into the images, and then subsequently recover them in the same processing as our real detections. This enables us to characterize the survey's completeness as a function of apparent magnitudes and on-sky rates of motion. We study the statistically optimal functional form for the magnitude, and develop a methodology that can estimate the magnitude and rate efficiencies for all survey's pointing groups simultaneously. We have determined that our peak completeness is on average 80\% in each pointing group, and our magnitude drops to $25\%$ of this value at $m_{25} = 26.22$. We describe the freely available survey simulation software and its methodology. We conclude by using it to infer that our effective search area for objects at 40 au is $14.8°^2$, and that our lack of dynamically cold distant objects means that there at most $8\times 10^3$ objects with $60 < a < 80$ au and absolute magnitudes $H \leq 8$. △ Less

Submitted 5 October, 2023; originally announced October 2023.

Comments: Accepted to AJ, companion paper to DEEP VI

The DECam Ecliptic Exploration Project (DEEP): V. The Absolute Magnitude Distribution of the Cold Classical Kuiper Belt

Authors: Kevin J. Napier, Hsing-Wen Lin, David W. Gerdes, Fred C. Adams, Anna M. Simpson, Matthew W. Porter, Katherine G. Weber, Larissa Markwardt, Gabriel Gowman, Hayden Smotherman, Pedro H. Bernardinelli, Mario Jurić, Andrew J. Connolly, J. Bryce Kalmbach, Stephen K. N. Portillo, David E. Trilling, Ryder Strauss, William J. Oldroyd, Chadwick A. Trujillo, Colin Orion Chandler, Matthew J. Holman, Hilke E. Schlichting, Andrew McNeill, the DEEP Collaboration

Abstract: The DECam Ecliptic Exploration Project (DEEP) is a deep survey of the trans-Neptunian solar system being carried out on the 4-meter Blanco telescope at Cerro Tololo Inter-American Observatory in Chile using the Dark Energy Camera (DECam). By using a shift-and-stack technique to achieve a mean limiting magnitude of $r \sim 26.2$, DEEP achieves an unprecedented combination of survey area and depth,… ▽ More The DECam Ecliptic Exploration Project (DEEP) is a deep survey of the trans-Neptunian solar system being carried out on the 4-meter Blanco telescope at Cerro Tololo Inter-American Observatory in Chile using the Dark Energy Camera (DECam). By using a shift-and-stack technique to achieve a mean limiting magnitude of $r \sim 26.2$, DEEP achieves an unprecedented combination of survey area and depth, enabling quantitative leaps forward in our understanding of the Kuiper Belt populations. This work reports results from an analysis of twenty 3 sq.\ deg.\ DECam fields along the invariable plane. We characterize the efficiency and false-positive rates for our moving-object detection pipeline, and use this information to construct a Bayesian signal probability for each detected source. This procedure allows us to treat all of our Kuiper Belt Object (KBO) detections statistically, simultaneously accounting for efficiency and false positives. We detect approximately 2300 candidate sources with KBO-like motion at S/N $>6.5$. We use a subset of these objects to compute the luminosity function of the Kuiper Belt as a whole, as well as the Cold Classical (CC) population. We also investigate the absolute magnitude ($H$) distribution of the CCs, and find consistency with both an exponentially tapered power-law, which is predicted by streaming instability models of planetesimal formation, and a rolling power law. Finally, we provide an updated mass estimate for the Cold Classical Kuiper Belt of $M_{CC}(H_r < 12) = 0.0017^{+0.0010}_{-0.0004} M_{\oplus}$, assuming albedo $p = 0.15$ and density $ρ= 1$ g cm$^{-3}$. △ Less

Submitted 18 September, 2023; originally announced September 2023.

Comments: Accepted by PSJ

The DECam Ecliptic Exploration Project (DEEP) IV: Constraints on the shape distribution of bright TNOs

Authors: R. Strauss, D. E. Trilling, P. H. Bernardinelli, C. Beach, W. J. Oldroyd, S. S. Sheppard, H. E. Schlichting, D. W. Gerdes, F. C. Adams, C. O. Chandler, C. Fuentes, M. J. Holman, M. Jurić, H. W. Lin, L. Markwardt, A. McNeill, M. Mommert, K. J. Napier, M. J. Payne, D. Ragozzine, A. S. Rivkin, H. Smotherman, C. A. Trujillo

Abstract: We present the methods and results from the discovery and photometric measurement of 26 bright (VR $>$ 24 trans-Neptunian objects (TNOs) during the first year (2019-20) of the DECam Ecliptic Exploration Project (DEEP). The DEEP survey is an observational TNO survey with wide sky coverage, high sensitivity, and a fast photometric cadence. We apply a computer vision technique known as a progressive… ▽ More We present the methods and results from the discovery and photometric measurement of 26 bright (VR $>$ 24 trans-Neptunian objects (TNOs) during the first year (2019-20) of the DECam Ecliptic Exploration Project (DEEP). The DEEP survey is an observational TNO survey with wide sky coverage, high sensitivity, and a fast photometric cadence. We apply a computer vision technique known as a progressive probabilistic Hough transform to identify linearly-moving transient sources within DEEP photometric catalogs. After subsequent visual vetting, we provide a photometric and astrometric catalog of our TNOs. By modeling the partial lightcurve amplitude distribution of the DEEP TNOs using Monte Carlo techniques, we find our data to be most consistent with an average TNO axis ratio b/a $<$ 0.5, implying a population dominated by non-spherical objects. Based on ellipsoidal gravitational stability arguments, we find our data to be consistent with a TNO population containing a high fraction of contact binaries or other extremely non-spherical objects. We also discuss our data as evidence that the expected binarity fraction of TNOs may be size-dependent. △ Less

Submitted 7 September, 2023; originally announced September 2023.

The DECam Ecliptic Exploration Project (DEEP): I. Survey description, science questions, and technical demonstration

Authors: David E. Trilling, David W. Gerdes, Mario Juric, Chadwick A. Trujillo, Pedro H. Bernardinelli, Kevin J. Napier, Hayden Smotherman, Ryder Strauss, Cesar Fuentes, Matthew J. Holman, Hsing Wen Lin, Larissa Markwardt, Andrew McNeill, Michael Mommert, William J. Oldroyd, Matthew J. Payne, Darin Ragozzine, Andrew S. Rivkin, Hilke Schlichting, Scott S. Sheppard, Fred C. Adams, Colin Orion Chandler

Abstract: We present here the DECam Ecliptic Exploration Project (DEEP), a three year NOAO/NOIRLab Survey that was allocated 46.5 nights to discover and measure the properties of thousands of trans-Neptunian objects (TNOs) to magnitudes as faint as VR~27, corresponding to sizes as small as 20 km diameter. In this paper we present the science goals of this project, the experimental design of our survey, and… ▽ More We present here the DECam Ecliptic Exploration Project (DEEP), a three year NOAO/NOIRLab Survey that was allocated 46.5 nights to discover and measure the properties of thousands of trans-Neptunian objects (TNOs) to magnitudes as faint as VR~27, corresponding to sizes as small as 20 km diameter. In this paper we present the science goals of this project, the experimental design of our survey, and a technical demonstration of our approach. The core of our project is "digital tracking," in which all collected images are combined at a range of motion vectors to detect unknown TNOs that are fainter than the single exposure depth of VR~23 mag. Through this approach we reach a depth that is approximately 2.5 magnitudes fainter than the standard LSST "wide fast deep" nominal survey depth of 24.5 mag. DEEP will more than double the number of known TNOs with observational arcs of 24 hours or more, and increase by a factor of 10 or more the number of known small (<50 km) TNOs. We also describe our ancillary science goals, including measuring the mean shape distribution of very small main belt asteroids, and briefly outline a set of forthcoming papers that present further aspects of and preliminary results from the DEEP program. △ Less

Submitted 6 September, 2023; originally announced September 2023.

Comments: AJ, in press. First in a series of papers

Models of Tokamak Disruptions

Authors: H. R. Strauss

Abstract: Disruptions are a serious issue in tokamaks. In a disruption, the thermal energy is lost by means of an instability which could be a resistive wall tearing mode (RWTM). During precursors to a disruption, the plasma edge region cools, causing the current to contract. Model sequences of contracted current equilibria are given, and their stability is calculated. A linear stability study shows that th… ▽ More Disruptions are a serious issue in tokamaks. In a disruption, the thermal energy is lost by means of an instability which could be a resistive wall tearing mode (RWTM). During precursors to a disruption, the plasma edge region cools, causing the current to contract. Model sequences of contracted current equilibria are given, and their stability is calculated. A linear stability study shows that there is a maximum value of edge $q_a \approx 3$ for RWTMs to occur. This also implies a minimum rational surface radius normalized to plasma radius from RWTMs to be unstable. Nonlinear simulations are performed using a similar model sequence derived from an equilibrium reconstruction. There is a striking difference in the results, depending on whether the wall is ideal or resistive. With an ideal wall, the perturbations saturate at moderate amplitude, causing a minor disruption without a thermal quench. With a resistive wall, there is a major disruption with a thermal quench, if the edge $q_a \le 3.$ There is a sharp transition in nonlinear behavior at $q_a = 3.$ This is consistent with the linear model and with experiments. If disruptions are caused by RWTMs, then devices with highly conducting walls, such as the International Tokamak Experimental Reactor (ITER) will experience much milder, tolerable, disruptions than presently predicted. △ Less

Submitted 15 August, 2023; originally announced August 2023.

Comments: arXiv admin note: text overlap with arXiv:2304.07994

High-Dimensional Bayesian Likelihood Normalisation for CRESST's Background Model

Authors: G. Angloher, S. Banik, G. Benato, A. Bento, A. Bertolini, R. Breier, C. Bucci, J. Burkhart, L. Canonica, A. D'Addabbo, S. Di Lorenzo, L. Einfalt, A. Erb, F. v. Feilitzsch, S. Fichtinger, D. Fuchs, A. Garai, V. M. Ghete, P. Gorla, P. V. Guillaumon, S. Gupta, D. Hauff, M. Jeskovsky, J. Jochum, M. Kaznacheeva , et al. (37 additional authors not shown)

Abstract: Using CaWO$_4$ crystals as cryogenic calorimeters, the CRESST experiment searches for nuclear recoils caused by the scattering of potential Dark Matter particles. A reliable identification of a potential signal crucially depends on an accurate background model. In this work we introduce an improved normalisation method for CRESST's model of the electromagnetic backgrounds. Spectral templates, base… ▽ More Using CaWO$_4$ crystals as cryogenic calorimeters, the CRESST experiment searches for nuclear recoils caused by the scattering of potential Dark Matter particles. A reliable identification of a potential signal crucially depends on an accurate background model. In this work we introduce an improved normalisation method for CRESST's model of the electromagnetic backgrounds. Spectral templates, based on Geant4 simulations, are normalised via a Bayesian likelihood fit to experimental background data. Contrary to our previous work, no assumption of partial secular equilibrium is required, which results in a more robust and versatile applicability. Furthermore, considering the correlation between all background components allows us to explain 82.7% of the experimental background within [1 keV, 40 keV], an improvement of 18.6% compared to our previous method. △ Less

Submitted 9 January, 2025; v1 submitted 19 July, 2023; originally announced July 2023.

Comments: 38 pages, 15 figures, accepted version to JINST

Journal ref: 2024 JINST 19 P11013

Spectroscopic Imaging of the Sun with MeerKAT: Opening a New Frontier in Solar Physics

Authors: Devojyoti Kansabanik, Surajit Mondal, Divya Oberoi, James O. Chibueze, N. E. Engelbrecht, R. D. Strauss, Eduard P. Kontar, Gert J. J. Botha, P. J. Steyn, Amore E. Nel

Abstract: Solar radio emissions provide several unique diagnostics to estimate different physical parameters of the solar corona, which are otherwise simply inaccessible. However, imaging the highly dynamic solar coronal emissions spanning a large range of angular scales at radio wavelengths is extremely challenging. At GHz frequencies, MeerKAT radio telescope is possibly globally the best-suited instrument… ▽ More Solar radio emissions provide several unique diagnostics to estimate different physical parameters of the solar corona, which are otherwise simply inaccessible. However, imaging the highly dynamic solar coronal emissions spanning a large range of angular scales at radio wavelengths is extremely challenging. At GHz frequencies, MeerKAT radio telescope is possibly globally the best-suited instrument at present for providing high-fidelity spectroscopic snapshot solar images. Here, we present the first published spectroscopic images of the Sun made using the observations with MeerKAT in the 880-1670 MHz band. This work demonstrates the high fidelity of spectroscopic snapshot MeerKAT solar images through a comparison with simulated radio images at MeerKAT frequencies. The observed images show extremely good morphological similarities with the simulated images. Our analysis shows that below ~900 MHz MeerKAT images can recover essentially the entire flux density from the large angular scale solar disc. Not surprisingly, at higher frequencies, the missing flux density can be as large as ~50%. However, it can potentially be estimated and corrected for. We believe once solar observation with MeerKAT is commissioned, it will enable a host of novel studies, open the door to a large unexplored phase space with significant discovery potential, and also pave the way for solar science with the upcoming Square Kilometre Array-Mid telescope, for which MeerKAT is a precursor. △ Less

Submitted 17 January, 2024; v1 submitted 4 July, 2023; originally announced July 2023.

Comments: Published at the Astrophysical Journal, 15 pages, 9 figures

Journal ref: ApJ 961 96 (2024)

Study of collision and $γ$-cascade times following neutron-capture processes in cryogenic detectors

Authors: CRAB collaboration, G. Soum-Sidikov, H. Abele, J. Burkhart, F. Cappella, N. Casali, R. Cerulli, A. Chalil, A. Chebboubi, J-P. Crocombette, G. del Castello, M. del Gallo Roccagiovine, A. Doblhammer, S. Dorer, E. Dumonteil, A. Erhart, A. Giuliani, C. Goupy, F. Gunsing, E. Jericha, M. Kaznacheeva, A. Kinast, H. Kluck, A. Langenkämper, T. Lasserre , et al. (25 additional authors not shown)

Abstract: The emission of $γ$-rays after a neutron capture in a cryogenic detector can generate mono-energetic nuclear recoils in the sub-keV regime, of direct interest for the calibration of Dark Matter and Coherent Elastic Neutrino Nucleus Scattering experiments. Here we show that accurate predictions of the nuclear recoil spectra induced by neutron captures require taking into account the interplay betwe… ▽ More The emission of $γ$-rays after a neutron capture in a cryogenic detector can generate mono-energetic nuclear recoils in the sub-keV regime, of direct interest for the calibration of Dark Matter and Coherent Elastic Neutrino Nucleus Scattering experiments. Here we show that accurate predictions of the nuclear recoil spectra induced by neutron captures require taking into account the interplay between the development in time of the de-excitation $γ$-cascade of the target nucleus and that of the associated atomic collisions in matter. We present detailed simulations coupling the FIFRELIN code for the description of the $γ$-cascades and the IRADINA code for the modelling of the fast atomic movements in matter. Nuclear recoil spectra are predicted, and made available to the community, for concrete cases of Al$_2$O$_3$, Si, Ge and CaWO$_4$ crystals exposed to a low intensity beam of thermal neutrons. We find that timing effects cause new calibration peaks to emerge in the recoil spectra and also impact the shape of the continuous recoil distribution. We discuss how they could give access to a rich physics program, spanning the accurate study of the response of cryogenic detectors in the sub-keV range, tests of solid state physics simulations and tests of nuclear models. △ Less

Submitted 17 May, 2023; originally announced May 2023.

On the onset delays of solar energetic electrons and protons: Evidence for a common accelerator

Authors: R. D. Strauss, N. Dresing, I. G. Richardson, J. P. van den Berg, P. J. Steyn

Abstract: The processes responsible for the acceleration of solar energetic particles (SEPs) are still not well understood, including whether SEP electrons and protons are accelerated by common or separate processes. Using a numerical particle transport model that includes both pitch-angle and perpendicular spatial diffusion, we simulate, amongst other quantities, the onset delay for MeV electrons and proto… ▽ More The processes responsible for the acceleration of solar energetic particles (SEPs) are still not well understood, including whether SEP electrons and protons are accelerated by common or separate processes. Using a numerical particle transport model that includes both pitch-angle and perpendicular spatial diffusion, we simulate, amongst other quantities, the onset delay for MeV electrons and protons and compare the results to observations of SEPs from widely-separated spacecraft. Such observations have previously been interpreted, in a simple scenario assuming no perpendicular diffusion, as evidence for different electron and proton sources. We show that, by assuming a common particle source together with perpendicular diffusion, we are able to simultaneously reproduce the onset delays for both electrons and protons. We argue that this points towards a common accelerator for these particles. Moreover, a relatively broad particle source is required in the model to correctly describe the observations. This is suggestive of diffusive shock acceleration occurring at large shock structures playing a significant role in the acceleration of these SEPs. △ Less

Submitted 9 May, 2023; originally announced May 2023.

Comments: Accepted to ApJ

A Model of Tokamak Locked Mode Disruptions

Authors: H. R. Strauss

Abstract: Locked modes are precursors to major disruptions. During locked modes, the temperature decreases in the plasma edge region. This causes the current to contract. A model is given to analyze the MHD stability of contracted current equilibria. If there is sufficient current contraction, resistive wall tearing modes are destabilized. This requires that the q = 2 surface be sufficiently close to the wa… ▽ More Locked modes are precursors to major disruptions. During locked modes, the temperature decreases in the plasma edge region. This causes the current to contract. A model is given to analyze the MHD stability of contracted current equilibria. If there is sufficient current contraction, resistive wall tearing modes are destabilized. This requires that the q = 2 surface be sufficiently close to the wall. The threshold conditions obtained in the model are consistent with experimental observations of the conditions for a thermal quench in a disruption. △ Less

Submitted 17 April, 2023; originally announced April 2023.

Comments: 7 pages, 3 figures

The radiation environment over the African continent at aviation altitudes: First results of the RPiRENA-based dosimeter

Authors: M. G. Mosotho, R. D. Strauss, S. Bottcher, C. Diedericks

Abstract: The radiation environment over the African continent, at aviation altitudes, remains mostly uncharacterized and unregulated. In this paper we present initial measurements made by a newly developed active dosimeter on-board long-haul flights between South Africa and Germany. Based on these initial tests, we believe that this low-cost and open-source dosimeter is suitable for continued operation ove… ▽ More The radiation environment over the African continent, at aviation altitudes, remains mostly uncharacterized and unregulated. In this paper we present initial measurements made by a newly developed active dosimeter on-board long-haul flights between South Africa and Germany. Based on these initial tests, we believe that this low-cost and open-source dosimeter is suitable for continued operation over the Africa continent and can provide valuable long-term measurements to test dosimteric models and inform aviation policy △ Less

Submitted 4 March, 2023; originally announced March 2023.

Comments: Accepted to appear in Journal of Space Weather and Space Climate

Observation of a low energy nuclear recoil peak in the neutron calibration data of the CRESST-III Experiment

Authors: CRESST Collaboration, G. Angloher, S. Banik, G. Benato, A. Bento, A. Bertolini, R. Breier, C. Bucci, J. Burkhart, L. Canonica, A. D'Addabbo, S. Di Lorenzo, L. Einfalt, A. Erb, F. v. Feilitzsch, S. Fichtinger, D. Fuchs, A. Fuss, A. Garai, V. M. Ghete, S. Gerster, P. Gorla, P. V. Guillaumon, S. Gupta, D. Hauff , et al. (36 additional authors not shown)

Abstract: New-generation direct searches for low mass dark matter feature detection thresholds at energies well below 100 eV, much lower than the energies of commonly used X-ray calibration sources. This requires new calibration sources with sub-keV energies. When searching for nuclear recoil signals, the calibration source should ideally cause mono-energetic nuclear recoils in the relevant energy range. Re… ▽ More New-generation direct searches for low mass dark matter feature detection thresholds at energies well below 100 eV, much lower than the energies of commonly used X-ray calibration sources. This requires new calibration sources with sub-keV energies. When searching for nuclear recoil signals, the calibration source should ideally cause mono-energetic nuclear recoils in the relevant energy range. Recently, a new calibration method based on the radiative neutron capture on $^{182}$W with subsequent de-excitation via single $γ$-emission leading to a nuclear recoil peak at 112 eV was proposed. The CRESST-III dark matter search operated several CaWO$_{4}$-based detector modules with detection thresholds below 100 eV in the past years. We report the observation of a peak around the expected energy of 112 eV in the data of three different detector modules recorded while irradiated with neutrons from different AmBe calibration sources. We compare the properties of the observed peaks with Geant-4 simulations and assess the prospects of using this for the energy calibration of CRESST-III detectors. △ Less

Submitted 25 July, 2023; v1 submitted 27 March, 2023; originally announced March 2023.

Comments: 8 pages, 4 figures; submitted to Phys. Rev. D

Journal ref: Phys. Rev. D 108, 022005 (2023)