Showing 1–50 of 113 results for author: Fry, J

The Cryogenic System of DMRadio-50L

Authors: V. Ankel, C. Bartram, J. Begin, C. Bell, S. Chaudhuri, H. -M. Cho, J. Corbin, W. Craddock, S. Cuadra, A. Droster, J. Echevers, E. Engelhardt, J. T. Fry, J. Fu, K. D. Irwin, A. Keller, R. Kolevatov, A. Kunder, D. Li, M. Marangola, N. Otto, K. M. W. Pappas, E. Pariset, S. Puranam, P. Quassolo , et al. (14 additional authors not shown)

Abstract: The DMRadio-50L experiment is designed to search for axion dark matter in the 5 kHz - 5 MHz frequency range using a lumped-element LC resonator and a toroidal magnet and to serve as a testbed for quantum sensors. This paper describes the custom cryogenic system developed to meet the stringent requirements of the experiment within a standard laboratory environment. The system is designed to cool a… ▽ More The DMRadio-50L experiment is designed to search for axion dark matter in the 5 kHz - 5 MHz frequency range using a lumped-element LC resonator and a toroidal magnet and to serve as a testbed for quantum sensors. This paper describes the custom cryogenic system developed to meet the stringent requirements of the experiment within a standard laboratory environment. The system is designed to cool a 200 kg detector assembly to temperatures as low as 50 mK while providing sufficient cooling power at multiple temperature stages. We present the conceptual design, technical implementation, and measured performance of the hybrid cryogenic system, which combines a horizontal dilution refrigerator with a large vertical payload cryostat. △ Less

Submitted 6 July, 2026; originally announced July 2026.

Stacked Ensemble Learning for Abdominal Aortic Aneurysm Segmentation in CT Angiography

Authors: Joshua Fry, Sajjad Arzemanzadeh, Saeideh Sekhavat, Mostafa Jamshidian, Adam Wittek, Michael Bertolacci, Elke R. Gizewski, Eva Gassner, Alexander Loizides, Maximillian Lutz, Florian K. Enzmann, Karol Miller

Abstract: Abdominal aortic aneurysm (AAA) rupture risk assessment increasingly relies on patient-specific biomechanical computations, which require accurate three-dimensional aneurysm geometry from computed tomography angiography (CTA). Manual and semi-automated segmentation remain time-consuming and observer-dependent, limiting their use in large-scale clinical workflows. In this study, we developed a stac… ▽ More Abdominal aortic aneurysm (AAA) rupture risk assessment increasingly relies on patient-specific biomechanical computations, which require accurate three-dimensional aneurysm geometry from computed tomography angiography (CTA). Manual and semi-automated segmentation remain time-consuming and observer-dependent, limiting their use in large-scale clinical workflows. In this study, we developed a stacked ensemble framework for automated AAA seg-mentation from CTA images. We used 40 anonymised contrast-enhanced CTA scans from AAA patients and generated reference segmentations using the nnInteractive extension in 3D Slicer. We partitioned the dataset into 32 training cases and 8 held-out test cases. Three nnUNetv2 configurations, Default, DA5, and ResEncL, were trained as base learners, and their voxel-wise probability out-puts were combined using an L2-regularised logistic regression meta-model trained from out-of-sample cross-validation predictions. We evaluated segmentation performance using Dice Coefficient and Separation Distance, a mean boundary-to-boundary distance measure introduced in this study to quantify average surface agreement. On the held-out test set, the ensemble achieved the highest mean Dice Coefficient of 0.9752 and the lowest mean Separation Distance of 0.4598 mm, indicating improved volumetric overlap and average boundary agreement compared with the individual base learners. Overall, stacked ensemble learning provided small but meaningful improvements in AAA segmentation, particularly for boundary accuracy relevant to downstream patient-specific bio-mechanical computations. △ Less

Submitted 1 July, 2026; originally announced July 2026.

Comments: 14 pages

DMRadio-Core: A new approach for GUT-scale axion searches

Authors: V. Ankel, C. Bartram, J. Begin, C. Bell, S. Chaudhuri, H. -M. Cho, J. Corbin, W. Craddock, S. Cuadra, A. Droster, J. Echevers, E. Engelhardt, J. T. Fry, K. D. Irwin, A. Keller, R. Kolevatov, A. Kunder, N. Kurita, N. Otto, E. Pariset, S. Puranam, P. Quassolo, N. M. Rapidis, C. P. Salemi, M. Simanovskaia , et al. (11 additional authors not shown)

Abstract: Searches for QCD axions with masses in the neV/$c^2$ mass range are strongly motivated by new physics at the GUT scale and by well-motivated pre-inflationary axion symmetry breaking scales. This parameter space is challenging to probe due to the small axion-photon couplings, which typically require large, high-field magnets with substantial stored energy. In this paper, we propose a new experiment… ▽ More Searches for QCD axions with masses in the neV/$c^2$ mass range are strongly motivated by new physics at the GUT scale and by well-motivated pre-inflationary axion symmetry breaking scales. This parameter space is challenging to probe due to the small axion-photon couplings, which typically require large, high-field magnets with substantial stored energy. In this paper, we propose a new experimental geometry based on a narrow-bore, segmented solenoid that optimizes the collection of the axion-induced signal using LC resonators outside the high-field region of the magnet bore. This alternative optimization significantly reduces the required stored magnetic energy while preserving sensitivity, enabling a near-term experiment in the 30-200 MHz (120-830 neV/$c^2$) range, with a cost-effective, staged scaling to a GUT-scale experiment in the 100 kHz-30 MHz (0.4-120 neV/$c^2$) range. △ Less

Submitted 9 July, 2026; v1 submitted 17 April, 2026; originally announced April 2026.

Comments: 10 pages, 6 figures. v2: Preparation for journal submission. Updated citations, changed one of the magnet configurations for DMRadio-GUT

Development of a Modular Current-Mode NaI(Tl) Detector Array for Parity Odd (n,γ) Cross Section Measurements

Authors: J. T. Mills, J. G. Otero Munoz, K. Dickerson, I. Britt, A. Couture, J. Doskow, J. Fry, I. Ide, M. Kitaguchi, R. Kobayashi, M. Luxnat, A. Moseley, R. Nakabe, I. Novikov, K. Oikawa, T. Oku, T. Okudaira, A. Quintinar-Peña, A. Richburg, S. Samiei, D. Schaper, H. M. Shimizu, D. Slone, W. M. Snow, S. Takada , et al. (4 additional authors not shown)

Abstract: The Neutron Optics Parity and Time-Reversal Violation Experiment (NOPTREX) Collaboration has developed a modular array of 24 NaI(Tl) detectors to measure parity and time-reversal symmetry violation in neutron-nucleus interactions. These detectors feature custom electronics that allow for operation in pulse or current mode. This paper describes the design, construction, characterization, and testin… ▽ More The Neutron Optics Parity and Time-Reversal Violation Experiment (NOPTREX) Collaboration has developed a modular array of 24 NaI(Tl) detectors to measure parity and time-reversal symmetry violation in neutron-nucleus interactions. These detectors feature custom electronics that allow for operation in pulse or current mode. This paper describes the design, construction, characterization, and testing of the detectors in this array. We demonstrate the ability of the array to detect parity-odd asymmetries in neutron resonances by observing the known 0.7 eV parity-violating resonance in 139La in measurements at LANSCE. △ Less

Submitted 7 April, 2026; originally announced April 2026.

Effects of Schwarzschild's Black Hole Singularities on Complex Scalar Field

Authors: Z. E. Musielak, J. L. Fry, G. W. Kanan

Abstract: Complex scalar fields described by a novel Klein-Gordon equation derived from gauge and group theories are considered at the Schwarzschild's black hole singularities. It is shown that the field is well-behaved in the vicinity of these singularities and that its value reaches zero at both singularities. The obtained results also demonstrate that the field forms a scalar hair that exists outside of… ▽ More Complex scalar fields described by a novel Klein-Gordon equation derived from gauge and group theories are considered at the Schwarzschild's black hole singularities. It is shown that the field is well-behaved in the vicinity of these singularities and that its value reaches zero at both singularities. The obtained results also demonstrate that the field forms a scalar hair that exists outside of the event horizon, and that the interior field is tachyonic and undergoes a tachyonic condensation to reach its true vacuum at the central singularity. The described field's behavior is very different from that predicted by the Klein-Gordon equation minimally coupled to gravity. Physical implications of these results for the interior structure of black holes are discussed. △ Less

Submitted 31 March, 2026; originally announced April 2026.

Comments: 21 pages and 2 Figures

Benchmarking Formula 1 results using a normal model

Authors: John Fry, Silvio Fanzon, Mark Austin, Tom Brighton

Abstract: There is enduring interest in disentangling the effects of skill and luck in sport. A key issue in Formula 1 is distinguishing between car-level and driver-level effects. Four elite teams currently dominate Formula 1 and have won every major race for the last four years. In this paper we use univariate and bivariate normal models to quantify reasonable performance expectations at both driver and t… ▽ More There is enduring interest in disentangling the effects of skill and luck in sport. A key issue in Formula 1 is distinguishing between car-level and driver-level effects. Four elite teams currently dominate Formula 1 and have won every major race for the last four years. In this paper we use univariate and bivariate normal models to quantify reasonable performance expectations at both driver and team levels, distinguishing between elite and non-elite teams. We illustrate our approach with an application to the last fully completed 2025 season. △ Less

Submitted 28 May, 2026; v1 submitted 16 March, 2026; originally announced March 2026.

A gaseous-helium cooling system for silicon detectors in the Nab experiment

Authors: Love Richburg, Noah Birge, Nadia Fomin, Grant Riley, Josh Pierce, John Ramsey, Wolfgang Schreyer, Seppo Penttila, Isaiah Wallace, Di'Arra Mostella, Aaron Jezghani, Alexander Saunders, Americo Salas Bacci, Ariella Atencio, August Mendelsohn, Austin Nelsen, Bryan Zeck, Christopher Crawford, Corey Gilbert, David Mathews, Deion Fellers, Duncan Fuehne, Erick Smith, Francisco Gonzalez, Glenn Randall , et al. (18 additional authors not shown)

Abstract: The Nab experiment aims to extract the neutron beta decay correlation coefficients 'a' and 'b'. This will be accomplished using a 7 m tall electromagnetic spectrometer which measures electron energies and proton momenta. Detection of electrons and protons resulting from neutron beta decay will be carried out using large-area, thick, highly-segmented, single-crystal silicon detectors. These detecto… ▽ More The Nab experiment aims to extract the neutron beta decay correlation coefficients 'a' and 'b'. This will be accomplished using a 7 m tall electromagnetic spectrometer which measures electron energies and proton momenta. Detection of electrons and protons resulting from neutron beta decay will be carried out using large-area, thick, highly-segmented, single-crystal silicon detectors. These detectors and accompanying electronics will be cooled by a recirculating, gaseous helium cooling system to below 150 K with +/- 0.5 K stability. We will motivate the need for detector cooling in the Nab experiment and discuss design and performance of this cooling system. △ Less

Submitted 8 January, 2026; originally announced January 2026.

From Commissioning to Precision Data-Taking: Resolving Operational Challenges in the Nab Detector Systems

Authors: L. J. Broussard, H. Acharya, R. Alarcon, S. Baeßler, M. Benoit, K. Borah, C. L. Britton, E. Brown, J. Choi, S. Clymer, C. Crawford, N. Ericson, L. Fabris, N. Fomin, J. Fry, R. Godri, F. M. Gonzalez, A. Hagemeier, J. Hamblen, S. Hollander, A. Jezghani, K. Leung, N. Macsai, M. Makela, D. Mathews , et al. (14 additional authors not shown)

Abstract: Our understanding of the weak mixing of quarks, described by the Cabibbo Kobayashi Maskawa (CKM) matrix, currently presents an anomaly. Thanks to major strides in both theory and experiment, improved precision in determinations of the first row of matrix elements has revealed disagreement with the expectation of unitarity. The Nab experiment at the Spallation Neutron Source is designed to precisel… ▽ More Our understanding of the weak mixing of quarks, described by the Cabibbo Kobayashi Maskawa (CKM) matrix, currently presents an anomaly. Thanks to major strides in both theory and experiment, improved precision in determinations of the first row of matrix elements has revealed disagreement with the expectation of unitarity. The Nab experiment at the Spallation Neutron Source is designed to precisely extract the first matrix element $V_{ud}$ and shed light on experimental tensions within the neutron beta decay dataset. Nab's asymmetric spectrometer allows coincident reconstruction of the decay proton and electron energies, which will be used to determine the electron-neutrino correlation coefficient, and thus (with the neutron lifetime) determine $V_{ud}$. This unique approach has provided a more comprehensive view of neutron beta decay, including a first observation of the full momentum phase space of the decay above detector thresholds and limits on exotic neutron states. Recent upgrades to the Nab detector system have improved the robustness and stability of the detector performance in terms of proton detection efficiency, noise performance, and detector segment availability, setting the stage for high precision physics data-taking. △ Less

Submitted 10 November, 2025; originally announced November 2025.

Comments: Submitted to Proceedings of the 29th International Nuclear Physics Conference (INPC 2025), Daejeon, South Korea, 25 - 30 May 2025. 6 pages. 4 figures

Tuning the Magnetic Anisotropy Energy of MoS$_2$-supported Mn$_{12}$ complexes by Electric Field: A First-Principles Study

Authors: Shuanglong Liu, Adam V. Bruce, Dmitry Skachkov, James N. Fry, Hai-Ping Cheng

Abstract: In this work, we examine low-energy adsorption configurations of four dodecanuclear manganese single-molecule magnets [Mn$_{12}$O$_{12}$(O$_2$CR)$_{16}$(H$_2$O)$_4$] (Mn$_{12}$), where the ligand R being H, CH$_3$, CHCl$_2$ or C$_6$H$_5$, on a molybdenum disulfide (MoS$_2$) monolayer using force field and density functional theory calculations. The van der Waals interaction is shown to be crucial… ▽ More In this work, we examine low-energy adsorption configurations of four dodecanuclear manganese single-molecule magnets [Mn$_{12}$O$_{12}$(O$_2$CR)$_{16}$(H$_2$O)$_4$] (Mn$_{12}$), where the ligand R being H, CH$_3$, CHCl$_2$ or C$_6$H$_5$, on a molybdenum disulfide (MoS$_2$) monolayer using force field and density functional theory calculations. The van der Waals interaction is shown to be crucial for determining the adsorption energy. Some electrons transfer from the substrate to the molecules upon surface adsorption, resulting in a reduction of the magnetic anisotropy energy of Mn$_{12}$. Since the lowest unoccupied molecular orbital of Mn$_{12}$ is close to the valence band of MoS$_2$, a negative electric field is more effective in modulating charge transfer and energy band alignment, and thus altering the magnetic anisotropy energy, compared with a positive electric field. A significant increase in the magnetic anisotropy energy of Mn$_{12}$ with the ligand R=CHCl$_2$ or R=C$_6$H$_5$ under a sufficiently high electric field has been predicted. Our calculations show that the molecules remain intact on the surface both before and after the electric field is applied. Finally, a two-level system formed by different adsorption configurations is evaluated, and the tunability of its energy barrier under an electric field is demonstrated. Our study sheds light on tuning the properties of single-molecule magnets using an electric field, when the molecules are supported on a surface. △ Less

Submitted 15 September, 2025; originally announced September 2025.

First Full Dalitz Plot Measurement in Neutron $β$-Decay using the Nab Spectrometer and Implications for New Physics

Authors: Francisco M. Gonzalez, Jin Ha Choi, Himal Acharya, Skylar Clymer, Andrew Hagemeier, David G. Mathews, August Mendelsohn, Austin Nelsen, Hitesh Rahangdale, Love Richburg, Ricardo Alarcon, Ariella Atencio, Stefan Baeßler, Thomas Bailey, Noah Birge, Dennis Borissenko, Michael Bowler, Leah J. Broussard, Albert T. Bryant, Jimmy Caylor, Tim Chupp, Christopher Crawford, R. Alston Croley, Micah Cruz, George Dodson , et al. (67 additional authors not shown)

Abstract: Precision measurements of observables in neutron $β$-decay are used to test the Standard Model description of the weak interaction and search for evidence of new physics. The Nab experiment at the Fundamental Neutron Physics Beamline at the Spallation Neutron Source was constructed to measure correlations in neutron decay by utilizing an asymmetric spectrometer and novel detection system to accura… ▽ More Precision measurements of observables in neutron $β$-decay are used to test the Standard Model description of the weak interaction and search for evidence of new physics. The Nab experiment at the Fundamental Neutron Physics Beamline at the Spallation Neutron Source was constructed to measure correlations in neutron decay by utilizing an asymmetric spectrometer and novel detection system to accurately reconstruct the proton momentum and electron energy for each $β$-decay. This work describes the detection of neutron $β$-decay products in the Nab spectrometer and presents the first full Dalitz plot representation of the phase space of neutron $β$-decay for all electrons >100 keV. In addition, new constraints are placed on a possible excited neutron state, hypothesized to explain the disagreement between the appearance and disappearance neutron lifetime techniques. △ Less

Submitted 21 August, 2025; originally announced August 2025.

Orthogonalized Synthetic Controls

Authors: Joseph Fry

Abstract: When conducting inference for the average treatment effect on the treated with a Synthetic Control Estimator, the vector of control weights is a nuisance parameter that is often constrained, high-dimensional, and may be only partially identified even when the average treatment effect on the treated is point-identified. All three of these features of a nuisance parameter can lead to failure of asym… ▽ More When conducting inference for the average treatment effect on the treated with a Synthetic Control Estimator, the vector of control weights is a nuisance parameter that is often constrained, high-dimensional, and may be only partially identified even when the average treatment effect on the treated is point-identified. All three of these features of a nuisance parameter can lead to failure of asymptotic normality for the estimate of the parameter of interest when using standard methods. I provide a new method that yields asymptotic normality for an estimate of average treatment effects, even when all three complications are present. This is accomplished by first estimating the control weights and any other nuisance parameters using a regularization penalty to achieve identification, and then estimating average treatment effects using moment conditions that are orthogonalized with respect to the nuisance parameters. Additionally, I extend results from the fixed-smoothing literature to provide tests that control size without requiring consistent standard errors. I present high-level sufficient conditions applicable to the traditional Synthetic Control Estimator as well as other weighting-based panel data methods, and verify them in an example involving instrumental variables. △ Less

Submitted 24 June, 2026; v1 submitted 30 June, 2025; originally announced July 2025.

High-Frequency Gravitational Wave Search with ABRACADABRA-10\,cm

Authors: Kaliroë M. W. Pappas, Jessica T. Fry, Sabrina Cheng, Arianna Colón Cesaní, Jonathan L. Ouellet, Chiara P. Salemi, Inoela Vital, Lindley Winslow, Valerie Domcke, Sung Mook Lee, Joshua W. Foster, Reyco Henning, Yonatan Kahn, Nicholas L. Rodd, Benjamin R. Safdi

Abstract: ABRACADABRA-10 cm has had great success as a pathfinder lumped-element axion dark matter experiment, setting limits on axion dark matter at the GUT scale. Now, using the interaction of gravitational waves with electrodynamics and a change in readout strategy, we use the ABRA-10 cm detector for the first search for high-frequency gravitational waves using a modified axion detector. Potential source… ▽ More ABRACADABRA-10 cm has had great success as a pathfinder lumped-element axion dark matter experiment, setting limits on axion dark matter at the GUT scale. Now, using the interaction of gravitational waves with electrodynamics and a change in readout strategy, we use the ABRA-10 cm detector for the first search for high-frequency gravitational waves using a modified axion detector. Potential sources at these high frequencies (10 kHz to 5 MHz) include merging primordial black hole binaries or superradiance, among other beyond the standard model phenomena. This paper presents the design, results, and challenges from the ABRA-10 cm high-frequency gravitational wave search, showing it is possible to simultaneously look for axions and high-frequency gravitational waves with both searches matching theoretical expectations for sensitivity. Additionally, we conducted the first time series transient search with data from an axion experiment, achieving sensitivity to $10^{-4}$ in strain. Scaled directly to the next generation axion experiment, DMRadio-GUT, this sensitivity would imply a reach to 0.01 $M_{\odot}$ primordial black hole mergers at distances around 3 pc, with prospects to go significantly further with modifications to the readout. △ Less

Submitted 5 May, 2025; originally announced May 2025.

Noise limits for dc SQUID readout of high-$Q$ resonators below 300 MHz

Authors: V. Ankel, C. Bartram, J. Begin, C. Bell, L. Brouwer, S. Chaudhuri, John Clarke, H. -M. Cho, J. Corbin, W. Craddock, S. Cuadra, A. Droster, M. Durkin, J. Echevers, J. T. Fry, G. Hilton, K. D. Irwin, A. Keller, R. Kolevatov, A. Kunder, D. Li, N. Otto, K. M. W. Pappas, N. M. Rapidis, C. P. Salemi , et al. (16 additional authors not shown)

Abstract: We present the limits on noise for the readout of cryogenic high-$Q$ resonators using dc Superconducting Quantum Interference Devices (SQUIDs) below 300 MHz. This analysis uses realized first-stage SQUIDs (previously published), whose performance is well described by Tesche-Clarke (TC) theory, coupled directly to the resonators. We also present data from a prototype second-stage dc SQUID array des… ▽ More We present the limits on noise for the readout of cryogenic high-$Q$ resonators using dc Superconducting Quantum Interference Devices (SQUIDs) below 300 MHz. This analysis uses realized first-stage SQUIDs (previously published), whose performance is well described by Tesche-Clarke (TC) theory, coupled directly to the resonators. We also present data from a prototype second-stage dc SQUID array designed to couple to this first-stage SQUID as a follow-on amplifier with high system bandwidth. This analysis is the first full consideration of dc SQUID noise performance referred to a high-$Q$ resonator over this frequency range, and is presented relative to the standard quantum limit. We include imprecision, backaction, and backaction-imprecision noise correlations from TC theory, the noise contributed by the second-stage SQUIDs, wiring, and preamplifiers, and optimizations for both on-resonance measurements and off-resonance scan sensitivity. This architecture has modern relevance due to the increased interest in axion searches and the requirements of the DMRadio-m$^3$ axion search, which will use dc SQUIDs in this frequency range. △ Less

Submitted 28 April, 2025; originally announced April 2025.

Comments: 17 pages, 4 figures

Journal ref: J. Appl. Phys. 138, 094505 (2025)

Affordable, manageable, practical, and scalable (AMPS) high-yield and high-gain inertial fusion

Authors: Andrew Alexander, Laura Robin Benedetti, Indrani Bhattacharyya, Jared Bowen, June Cabatu, Virgil Cacdac, Chhavi Chhavi, Chiatai Chen, Karen Chen, Dan Clark, Jerry Clark, Tyler Cope, Will Dannemann, Scott Davidson, David DeHaan, John Dugan, Mindy Eihusen, C. Leland Ellison, Carlos Esquivel, David Ethridge, Blake Ferguson, Bryan Ferguson, Jon Fry, Fernando Garcia-Rubio, Tarun Goyal , et al. (41 additional authors not shown)

Abstract: High-yield inertial fusion offers a transformative path to affordable clean firm power and advanced defense capabilities. Recent milestones at large facilities, particularly the National Ignition Facility (NIF), have demonstrated the feasibility of ignition but highlight the need for approaches that can deliver large amounts of energy to fusion targets at much higher efficiency and lower cost. We… ▽ More High-yield inertial fusion offers a transformative path to affordable clean firm power and advanced defense capabilities. Recent milestones at large facilities, particularly the National Ignition Facility (NIF), have demonstrated the feasibility of ignition but highlight the need for approaches that can deliver large amounts of energy to fusion targets at much higher efficiency and lower cost. We propose that pulser-driven inertial fusion energy (IFE), which uses high-current pulsed-power technology to compress targets to thermonuclear conditions, can achieve this goal. In this paper, we detail the physics basis for pulser IFE, focusing on magnetized liner inertial fusion (MagLIF), where cylindrical metal liners compress DT fuel under strong magnetic fields and pre-heat. We discuss how the low implosion velocities, direct-drive efficiency, and scalable pulser architecture can achieve ignition-level conditions at low capital cost. Our multi-dimensional simulations, benchmarked against experiments at the Z facility, show that scaling from 20 MA to 50-60 MA of current enables net facility gain. We then introduce our Demonstration System (DS), a pulsed-power driver designed to deliver more than 60 MA and store approximately 80 MJ of energy. The DS is designed to achieve a 1000x increase in effective performance compared to the NIF, delivering approximately 100x greater facility-level energy gain -- and importantly, achieving net facility gain, or Qf>1 -- at just 1/10 the capital cost. We also examine the engineering requirements for repetitive operation, target fabrication, and chamber maintenance, highlighting a practical roadmap to commercial power plants. △ Less

Submitted 14 April, 2025; originally announced April 2025.

Comments: 41 pages, 21 figures

Kaon Physics: A Cornerstone for Future Discoveries

Authors: Jason Aebischer, Atakan Tugberk Akmete, Riccardo Aliberti, Wolfgang Altmannshofer, Fabio Ambrosino, Roberto Ammendola, Antonella Antonelli, Giuseppina Anzivino, Saiyad Ashanujjaman, Laura Bandiera, Damir Becirevic, Véronique Bernard, Johannes Bernhard, Cristina Biino, Johan Bijnens, Monika Blanke, Brigitte Bloch-Devaux, Marzia Bordone, Peter Boyle, Alexandru Mario Bragadireanu, Francesco Brizioli, Joachim Brod, Andrzej J. Buras, Dario Buttazzo, Nicola Canale , et al. (131 additional authors not shown)

Abstract: The kaon physics programme, long heralded as a cutting-edge frontier by the European Strategy for Particle Physics, continues to stand at the intersection of discovery and innovation in high-energy physics (HEP). With its unparalleled capacity to explore new physics at the multi-TeV scale, kaon research is poised to unveil phenomena that could reshape our understanding of the Universe. This docume… ▽ More The kaon physics programme, long heralded as a cutting-edge frontier by the European Strategy for Particle Physics, continues to stand at the intersection of discovery and innovation in high-energy physics (HEP). With its unparalleled capacity to explore new physics at the multi-TeV scale, kaon research is poised to unveil phenomena that could reshape our understanding of the Universe. This document highlights the compelling physics case, with emphasis on exciting new opportunities for advancing kaon physics not only in Europe but also on a global stage. As an important player in the future of HEP, the kaon programme promises to drive transformative breakthroughs, inviting exploration at the forefront of scientific discovery. △ Less

Submitted 28 March, 2025; originally announced March 2025.

Comments: 10 pages, one figure, submitted to the European Strategy for Particle Physics Update

Machine Learning Assisted Modeling of Amorphous TiO$_2$-Doped GeO$_2$ for Advanced LIGO Mirror Coatings

Authors: Jun Jiang, Rui Zhang, Kiran Prasai, Riccardo Bassiri, James N. Fry, Martin M. Fejer, Hai-Ping Cheng

Abstract: The mechanical loss angle of amorphous TiO$_2$-doped GeO$_2$ can be lower than 10$^{-4}$, making it a candidate for Laser Interferometer Gravitational-wave Observatory (LIGO) mirror coatings. Amorphous oxides have complex atomic structures that are influenced by various factors, including doping concentration, preparation, and thermal history, resulting in different mass densities and physical pro… ▽ More The mechanical loss angle of amorphous TiO$_2$-doped GeO$_2$ can be lower than 10$^{-4}$, making it a candidate for Laser Interferometer Gravitational-wave Observatory (LIGO) mirror coatings. Amorphous oxides have complex atomic structures that are influenced by various factors, including doping concentration, preparation, and thermal history, resulting in different mass densities and physical properties. Modeling at atomistic level enables capturing these effects by generating atomic structure models according to experimental conditions. In order to obtain reliable and physical amorphous models at an affordable cost, we develop classical and machine-learning potentials (MLP) to speed up simulations. First-principles calculations are used to train and validate MLP as well as validating structure models. To better reproduce properties such as elastic modulus, radial distribution function (RDF) and the variations in mass density of doped amorphous oxides, density functional theory (DFT) calculations are used to optimize the final models. We find that the mass densities of amorphous systems are correlated with the total void volume. The experimental mass density matches the models with the most symmetric potential energy wells under volume change. The elastic response of the metal-oxygen network is also studied. The 27\% TiO$_2$ doped GeO$_2$ system shows the least number of large atom-atom distance changes, while for 44\% TiO$_2$ doped GeO$_2$, a majority of Ti-O distances are significantly changed. In response to strains, the metal-oxygen network at low mass densities prefers to adjust bond angles, while at high mass densities, the adjustment is mainly done by changing atom-atom distance. △ Less

Submitted 27 March, 2025; originally announced March 2025.

Comments: 8 pages, 5 figures, under review and revision PRM

Proposal of the KOTO II experiment

Authors: Jung Keun Ahn, Antonella Antonelli, Giuseppina Anzivino, Emile Augustine, Laura Bandiera, Jianming Bian, Francesco Brizioli, Stefano De Capua, Gabriella Carini, Veronika Chobanova, Giancarlo D'Ambrosio, John Bourke Dainton, Babette Dőbrich, John Fry, Alberto Gianoli, Alexander Glazov, Mario Gonzalez, Martin Gorbahn, Evgueni Goudzovski, Mei Homma, Yee B. Hsiung, Tomáš Husek, David Hutchcroft, Abhishek Iyer, Roger William Lewis Jones , et al. (57 additional authors not shown)

Abstract: The KOTO II experiment is proposed to measure the branching ratio of the decay $K_L\toπ^0ν\barν$ at J-PARC. With a beamline to extract long-lived neutral kaons at 5 degrees from a production target, the single event sensitivity of the decay is $8.5\times 10^{-13}$, which is much smaller than the Standard Model prediction $3\times 10^{-11}$. This allows searches for new physics beyond the Standard… ▽ More The KOTO II experiment is proposed to measure the branching ratio of the decay $K_L\toπ^0ν\barν$ at J-PARC. With a beamline to extract long-lived neutral kaons at 5 degrees from a production target, the single event sensitivity of the decay is $8.5\times 10^{-13}$, which is much smaller than the Standard Model prediction $3\times 10^{-11}$. This allows searches for new physics beyond the Standard Model and the first discovery of the decay with a significance exceeding $5σ$. As the only experiment proposed in the world dedicated to rare kaon decays, KOTO II will be indispensable in the quest for a complete understanding of flavor dynamics in the quark sector. Moreover, by combining efforts from the kaon community worldwide, we plan to develop the KOTO II detector further and expand the physics reach of the experiment to include measurements of the branching ratio of the $K_L\toπ^0\ell^+\ell^-$ decays, studies of other $K_L$ decays, and searches for dark photons, axions, and axion-like particles. KOTO II will therefore obtain a comprehensive understanding of $K_L$ decays, providing further constraints on new physics scenarios with existing $K^+$ results. △ Less

Submitted 22 January, 2025; originally announced January 2025.

Comments: Submitted to the J-PARC PAC. arXiv admin note: substantial text overlap with arXiv:2110.04462

Elementary econometric and strategic analysis of curling matches

Authors: John Fry, Mark Austin, Silvio Fanzon

Abstract: We develop a Markov model of curling matches, parametrised by the probability of winning an end and the probability distribution of scoring ends. In practical applications, these end-winning probabilities can be estimated econometrically, and are shown to depend on which team holds the hammer, as well as the offensive and defensive strengths of the respective teams. Using a maximum entropy argumen… ▽ More We develop a Markov model of curling matches, parametrised by the probability of winning an end and the probability distribution of scoring ends. In practical applications, these end-winning probabilities can be estimated econometrically, and are shown to depend on which team holds the hammer, as well as the offensive and defensive strengths of the respective teams. Using a maximum entropy argument, based on the idea of characteristic scoring patterns in curling, we predict that the points distribution of scoring ends should follow a constrained geometric distribution. We provide analytical results detailing when it is optimal to blank the end in preference to scoring one point and losing possession of the hammer. Statistical and simulation analysis of international curling matches is also performed. △ Less

Submitted 4 November, 2024; v1 submitted 18 June, 2024; originally announced June 2024.

Journal ref: Managerial Finance, 2024

TIDMAD: Time Series Dataset for Discovering Dark Matter with AI Denoising

Authors: J. T. Fry, Xinyi Hope Fu, Zhenghao Fu, Kaliroe M. W. Pappas, Lindley Winslow, Aobo Li

Abstract: Dark matter makes up approximately 85% of total matter in our universe, yet it has never been directly observed in any laboratory on Earth. The origin of dark matter is one of the most important questions in contemporary physics, and a convincing detection of dark matter would be a Nobel-Prize-level breakthrough in fundamental science. The ABRACADABRA experiment was specifically designed to search… ▽ More Dark matter makes up approximately 85% of total matter in our universe, yet it has never been directly observed in any laboratory on Earth. The origin of dark matter is one of the most important questions in contemporary physics, and a convincing detection of dark matter would be a Nobel-Prize-level breakthrough in fundamental science. The ABRACADABRA experiment was specifically designed to search for dark matter. Although it has not yet made a discovery, ABRACADABRA has produced several dark matter search results widely endorsed by the physics community. The experiment generates ultra-long time-series data at a rate of 10 million samples per second, where the dark matter signal would manifest itself as a sinusoidal oscillation mode within the ultra-long time series. In this paper, we present the TIDMAD -- a comprehensive data release from the ABRACADABRA experiment including three key components: an ultra-long time series dataset divided into training, validation, and science subsets; a carefully-designed denoising score for direct model benchmarking; and a complete analysis framework which produces a community-standard dark matter search result suitable for publication as a physics paper. This data release enables core AI algorithms to extract the dark matter signal and produce real physics results thereby advancing fundamental science. The data downloading and associated analysis scripts are available at https://github.com/jessicafry/TIDMAD △ Less

Submitted 28 October, 2025; v1 submitted 5 June, 2024; originally announced June 2024.

Comments: Accepted by NeurIPS 2025 (Spotlight)

Simulating decoherence of two coupled spins using the generalized cluster correlation expansion

Authors: Xiao Chen, Silas Hoffman, James N. Fry, Hai-Ping Cheng

Abstract: We simulate the coherence of two coupled electron spins interacting with a bath of nuclei using the generalized cluster correlation expansion (gCCE) method. An exchange interaction between the electrons facilitates a family of entangling gates that can be spoiled by nuclear-induced dephasing. Consequently, we study the dephasing of the coherent two-electron system by characterizing the $T_2$ and… ▽ More We simulate the coherence of two coupled electron spins interacting with a bath of nuclei using the generalized cluster correlation expansion (gCCE) method. An exchange interaction between the electrons facilitates a family of entangling gates that can be spoiled by nuclear-induced dephasing. Consequently, we study the dephasing of the coherent two-electron system by characterizing the $T_2$ and $T_2^*$ of the two-electron reduced density matrix for various system parameters in the range mimicking magnetic molecules, including magnetic field strength and orientation, exchange interaction strength, distance between the two spins, minimum distance between electron and nuclei and between nuclei, and nuclei density. We find the optimal regime for each parameter in which the coherence time is maximized and provide a physical understanding of it. △ Less

Submitted 7 January, 2026; v1 submitted 28 February, 2024; originally announced February 2024.

Journal ref: J. Chem. Phys. 163, 224111 (2025)

Faster identification of faster Formula 1 drivers via time-rank duality

Authors: John Fry, Tom Brighton, Silvio Fanzon

Abstract: Two natural ways of modelling Formula 1 race outcomes are a probabilistic approach, based on the exponential distribution, and econometric modelling of the ranks. Both approaches lead to exactly soluble race-winning probabilities. Equating race-winning probabilities leads to a set of equivalent parametrisations. This time-rank duality is attractive theoretically and leads to quicker ways of dis-en… ▽ More Two natural ways of modelling Formula 1 race outcomes are a probabilistic approach, based on the exponential distribution, and econometric modelling of the ranks. Both approaches lead to exactly soluble race-winning probabilities. Equating race-winning probabilities leads to a set of equivalent parametrisations. This time-rank duality is attractive theoretically and leads to quicker ways of dis-entangling driver and car level effects. △ Less

Submitted 25 March, 2024; v1 submitted 22 December, 2023; originally announced December 2023.

Comments: 9 pages

MSC Class: 62P25; 91-10; 62M99; 65C05

Journal ref: Economics Letters, 237, 111671, 2024

A Method of Moments Approach to Asymptotically Unbiased Synthetic Controls

Authors: Joseph Fry

Abstract: A common approach to constructing a Synthetic Control unit is to fit on the outcome variable and covariates in pre-treatment time periods, but it has been shown by Ferman and Pinto (2019) that this approach does not provide asymptotic unbiasedness when the fit is imperfect and the number of controls is fixed. Many related panel methods have a similar limitation when the number of units is fixed. I… ▽ More A common approach to constructing a Synthetic Control unit is to fit on the outcome variable and covariates in pre-treatment time periods, but it has been shown by Ferman and Pinto (2019) that this approach does not provide asymptotic unbiasedness when the fit is imperfect and the number of controls is fixed. Many related panel methods have a similar limitation when the number of units is fixed. I introduce and evaluate a new method in which the Synthetic Control is constructed using a General Method of Moments approach where units not being included in the Synthetic Control are used as instruments. I show that a Synthetic Control Estimator of this form will be asymptotically unbiased as the number of pre-treatment time periods goes to infinity, even when pre-treatment fit is imperfect and the number of units is fixed. Furthermore, if both the number of pre-treatment and post-treatment time periods go to infinity, then averages of treatment effects can be consistently estimated. I conduct simulations and an empirical application to compare the performance of this method with existing approaches in the literature. △ Less

Submitted 5 March, 2024; v1 submitted 2 December, 2023; originally announced December 2023.

Fundamental Neutron Physics: a White Paper on Progress and Prospects in the US

Authors: R. Alarcon, A. Aleksandrova, S. Baeßler, D. H. Beck, T. Bhattacharya, M. Blatnik, T. J. Bowles, J. D. Bowman, J. Brewington, L. J. Broussard, A. Bryant, J. F. Burdine, J. Caylor, Y. Chen, J. H. Choi, L. Christie, T. E. Chupp, V. Cianciolo, V. Cirigliano, S. M. Clayton, B. Collett, C. Crawford, W. Dekens, M. Demarteau, D. DeMille , et al. (66 additional authors not shown)

Abstract: Fundamental neutron physics, combining precision measurements and theory, probes particle physics at short range with reach well beyond the highest energies probed by the LHC. Significant US efforts are underway that will probe BSM CP violation with orders of magnitude more sensitivity, provide new data on the Cabibbo anomaly, more precisely measure the neutron lifetime and decay, and explore hadr… ▽ More Fundamental neutron physics, combining precision measurements and theory, probes particle physics at short range with reach well beyond the highest energies probed by the LHC. Significant US efforts are underway that will probe BSM CP violation with orders of magnitude more sensitivity, provide new data on the Cabibbo anomaly, more precisely measure the neutron lifetime and decay, and explore hadronic parity violation. World-leading results from the US Fundamental Neutron Physics community since the last Long Range Plan, include the world's most precise measurement of the neutron lifetime from UCN$τ$, the final results on the beta-asymmetry from UCNA and new results on hadronic parity violation from the NPDGamma and n-${^3}$He runs at the FNPB (Fundamental Neutron Physics Beamline), precision measurement of the radiative neutron decay mode and n-${}^4$He at NIST. US leadership and discovery potential are ensured by the development of new high-impact experiments including BL3, Nab, LANL nEDM and nEDM@SNS. On the theory side, the last few years have seen results for the neutron EDM from the QCD $θ$ term, a factor of two reduction in the uncertainty for inner radiative corrections in beta-decay which impacts CKM unitarity, and progress on {\it ab initio} calculations of nuclear structure for medium-mass and heavy nuclei which can eventually improve the connection between nuclear and nucleon EDMs. In order to maintain this exciting program and capitalize on past investments while also pursuing new ideas and building US leadership in new areas, the Fundamental Neutron Physics community has identified a number of priorities and opportunities for our sub-field covering the time-frame of the last Long Range Plan (LRP) under development. This white paper elaborates on these priorities. △ Less

Submitted 17 August, 2023; originally announced August 2023.

Comments: arXiv admin note: text overlap with arXiv:2304.03451

Spin decoherence in VOPc@graphene nanoribbon complexes

Authors: Xiao Chen, James N. Fry, H. P. Cheng

Abstract: Carbon nanoribbon or nanographene qubit arrays can facilitate quantum-to-quantum transduction between light, charge, and spin, making them an excellent testbed for fundamental science in quantum coherent systems and for the construction of higher-level qubit circuits. In this work, we study spin decoherence due to coupling with a surrounding nuclear spin bath of an electronic molecular spin of a v… ▽ More Carbon nanoribbon or nanographene qubit arrays can facilitate quantum-to-quantum transduction between light, charge, and spin, making them an excellent testbed for fundamental science in quantum coherent systems and for the construction of higher-level qubit circuits. In this work, we study spin decoherence due to coupling with a surrounding nuclear spin bath of an electronic molecular spin of a vanadyl phthalocyanine (VOPc) molecule integrated on an armchair-edged graphene nanoribbon (GNR). Density functional theory (DFT) is used to obtain ground state atomic configurations. Decay of spin coherence in Hahn echo experiments is then simulated using the cluster correlation expansion method with a spin Hamiltonian involving hyperfine and electric field gradient tensors calculated from DFT. We find that the decoherence time $T_2$ is anisotropic with respect to magnetic field orientation and determined only by the hydrogen nuclear spins both on VOPc and GNR. Large electron spin echo envelope modulation (ESEEM) due to nitrogen and vanadium nuclear spins is present at specific field ranges and can be completely suppressed by tuning the magnetic field. The relation between these field ranges and the hyperfine interactions is analyzed. The effects of interactions with the nuclear quadrupole moments are also studied, validating the applicability and limitations of the spin Hamiltonian when they are disregarded. △ Less

Submitted 31 July, 2023; originally announced July 2023.

Fundamental Symmetries, Neutrons, and Neutrinos (FSNN): Whitepaper for the 2023 NSAC Long Range Plan

Authors: B. Acharya, C. Adams, A. A. Aleksandrova, K. Alfonso, P. An, S. Baeßler, A. B. Balantekin, P. S. Barbeau, F. Bellini, V. Bellini, R. S. Beminiwattha, J. C. Bernauer, T. Bhattacharya, M. Bishof, A. E. Bolotnikov, P. A. Breur, M. Brodeur, J. P. Brodsky, L. J. Broussard, T. Brunner, D. P. Burdette, J. Caylor, M. Chiu, V. Cirigliano, J. A. Clark , et al. (154 additional authors not shown)

Abstract: This whitepaper presents the research priorities decided on by attendees of the 2022 Town Meeting for Fundamental Symmetries, Neutrons and Neutrinos, which took place December 13-15, 2022 in Chapel Hill, NC, as part of the Nuclear Science Advisory Committee (NSAC) 2023 Long Range Planning process. A total of 275 scientists registered for the meeting. The whitepaper makes a number of explicit recom… ▽ More This whitepaper presents the research priorities decided on by attendees of the 2022 Town Meeting for Fundamental Symmetries, Neutrons and Neutrinos, which took place December 13-15, 2022 in Chapel Hill, NC, as part of the Nuclear Science Advisory Committee (NSAC) 2023 Long Range Planning process. A total of 275 scientists registered for the meeting. The whitepaper makes a number of explicit recommendations and justifies them in detail. △ Less

Submitted 6 April, 2023; originally announced April 2023.

RASCBEC: RAman Spectroscopy Calculation via Born Effective Charge

Authors: Rui Zhang, Jun Jiang, Alec Mishkin, James N. Fry, Hai-Ping Cheng

Abstract: We advance the algorithm for ab initio calculations of Raman spectra for large systems via applying external electric field, and complement it by a code implementation we name RASCBEC. With the RASCBEC code, we have successfully benchmark crystalline materials and compute Raman spectra of large molecules, and amorphous oxides. Our results demonstrate a remarkable level of agreement with the result… ▽ More We advance the algorithm for ab initio calculations of Raman spectra for large systems via applying external electric field, and complement it by a code implementation we name RASCBEC. With the RASCBEC code, we have successfully benchmark crystalline materials and compute Raman spectra of large molecules, and amorphous oxides. Our results demonstrate a remarkable level of agreement with the results from other commonly used codes as well as the experimental data. The electric field approach for Raman spectra calculation is designed to overcome the computational challenges associated with the conventional approach, which requires the calculation of the macroscopic dielectric tensor at numerous molecular geometries. The key innovation in our approach lies in obtaining the first-order derivatives with respect to the external electric field directly from VASP (the Vienna Ab Initio Simulation Package), as the Born Effective Charge (BEC). The RASCBEC code not only significantly reduces computational time, up to a factor of $N/8$, compared to the conventional approach, where $N$ is the total count of atoms within the simulation box. But also maintains the same level of accuracy, employing first-order numerical derivatives that avoid the numerical noise associated with algorithms requiring second-order derivatives, as seen in other electric field-based methods. This advantage makes RASCBEC particularly beneficial for large molecules and expansive amorphous systems. △ Less

Submitted 27 March, 2024; v1 submitted 17 March, 2023; originally announced March 2023.

Electromagnetic modeling and science reach of DMRadio-m$^3$

Authors: DMRadio Collaboration, A. AlShirawi, V. Ankel, C. Bartram, J. Begin, C. Bell, J. N. Benabou, L. Brouwer, S. Chaudhuri, H. -M. Cho, J. Corbin, W. Craddock, S. Cuadra, A. Droster, J. Echevers, J. W. Foster, J. T. Fry, P. W. Graham, R. Henning, K. D. Irwin, F. Kadribasic, Y. Kahn, A. Keller, R. Kolevatov, S. Kuenstner , et al. (23 additional authors not shown)

Abstract: DMRadio-m$^3$ is an experiment that is designed to be sensitive to KSVZ and DFSZ QCD axion models in the 10--200\,MHz (41 neV$/c^2$ -- 0.83 $μ$eV/$c^2$) range. The experiment uses a solenoidal dc magnetic field to convert an axion dark-matter signal to an ac electromagnetic response in a coaxial copper pickup. The current induced by this axion signal is measured by dc SQUIDs. In this work, we pres… ▽ More DMRadio-m$^3$ is an experiment that is designed to be sensitive to KSVZ and DFSZ QCD axion models in the 10--200\,MHz (41 neV$/c^2$ -- 0.83 $μ$eV/$c^2$) range. The experiment uses a solenoidal dc magnetic field to convert an axion dark-matter signal to an ac electromagnetic response in a coaxial copper pickup. The current induced by this axion signal is measured by dc SQUIDs. In this work, we present the electromagnetic modeling of the response of the experiment to an axion signal over the full frequency range of DMRadio-m$^3$, which extends from the low-frequency, lumped-element limit to a regime where the axion Compton wavelength is only a factor of two larger than the detector size. With these results, we determine the live time and sensitivity of the experiment. The primary science goal of sensitivity to DFSZ axions across 30--200 MHz can be achieved with a $3σ$ live scan time of 2.9 years. △ Less

Submitted 6 May, 2025; v1 submitted 27 February, 2023; originally announced February 2023.

Comments: 14 pages, 7 figures. Updated scan times due to new SQUID noise numbers. Prepared for submission to journal

Journal ref: Phys. Rev. D 112, 052001 (2025)

HIKE, High Intensity Kaon Experiments at the CERN SPS

Authors: E. Cortina Gil, J. Jerhot, N. Lurkin, T. Numao, B. Velghe, V. W. S. Wong, D. Bryman, L. Bician, Z. Hives, T. Husek, K. Kampf, M. Koval, A. T. Akmete, R. Aliberti, V. Büscher, L. Di Lella, N. Doble, L. Peruzzo, M. Schott, H. Wahl, R. Wanke, B. Döbrich, L. Montalto, D. Rinaldi, F. Dettori , et al. (154 additional authors not shown)

Abstract: A timely and long-term programme of kaon decay measurements at a new level of precision is presented, leveraging the capabilities of the CERN Super Proton Synchrotron (SPS). The proposed programme is firmly anchored on the experience built up studying kaon decays at the SPS over the past four decades, and includes rare processes, CP violation, dark sectors, symmetry tests and other tests of the St… ▽ More A timely and long-term programme of kaon decay measurements at a new level of precision is presented, leveraging the capabilities of the CERN Super Proton Synchrotron (SPS). The proposed programme is firmly anchored on the experience built up studying kaon decays at the SPS over the past four decades, and includes rare processes, CP violation, dark sectors, symmetry tests and other tests of the Standard Model. The experimental programme is based on a staged approach involving experiments with charged and neutral kaon beams, as well as operation in beam-dump mode. The various phases will rely on a common infrastructure and set of detectors. △ Less

Submitted 29 November, 2022; originally announced November 2022.

Comments: Letter of Intent submitted to CERN SPSC. Address all correspondence to hike-eb@cern.ch

Report number: CERN-SPSC-2022-031/SPSC-I-257

Measurement of the Parity-Odd Angular Distribution of Gamma Rays From Polarized Neutron Capture on $^{35}$Cl

Authors: N. Fomin, R. Alarcon, L. Alonzi, E. Askanazi, S. Baeßler, S. Balascuta, L. Barrón-Palos, A. Barzilov, D. Blyth, J. D. Bowman, N. Birge, J. R. Calarco, T. E. Chupp, V. Cianciolo, C. E. Coppola, C. B. Crawford, K. Craycraft, D. Evans, C. Fieseler, E. Frlež, J. Fry, I. Garishvili, M. T. W. Gericke, R. C. Gillis, K. B. Grammer , et al. (39 additional authors not shown)

Abstract: We report a measurement of two energy-weighted gamma cascade angular distributions from polarized slow neutron capture on the ${}^{35}$Cl nucleus, one parity-odd correlation proportional to $\vec{s_{n}} \cdot \vec{k_γ}$ and one parity-even correlation proportional to $\vec{s_{n}} \cdot \vec{k_{n}} \times \vec{k_γ}$. A parity violating asymmetry can appear in this reaction due to the weak nucleon-n… ▽ More We report a measurement of two energy-weighted gamma cascade angular distributions from polarized slow neutron capture on the ${}^{35}$Cl nucleus, one parity-odd correlation proportional to $\vec{s_{n}} \cdot \vec{k_γ}$ and one parity-even correlation proportional to $\vec{s_{n}} \cdot \vec{k_{n}} \times \vec{k_γ}$. A parity violating asymmetry can appear in this reaction due to the weak nucleon-nucleon (NN) interaction which mixes opposite parity S and P-wave levels in the excited compound $^{36}$Cl nucleus formed upon slow neutron capture. If parity-violating (PV) and parity-conserving (PC) terms both exist, the measured differential cross section can be related to them via $\frac{dσ}{dΩ}\propto1+A_{γ, PV}\cosθ+A_{γ,PC}\sinθ$. The PV and PC asymmetries for energy-weighted gamma cascade angular distributions for polarized slow neutron capture on $^{35}$Cl averaged over the neutron energies from 2.27~meV to 9.53~meV were measured to be $A_{γ,PV}=(-23.9\pm0.7)\times 10^{-6}$ and $A_{γ,PC}=(0.1\pm0.7)\times 10^{-6}$. These results are consistent with previous experimental results. Systematic errors were quantified and shown to be small compared to the statistical error. These asymmetries in the angular distributions of the gamma rays emitted from the capture of polarized neutrons in $^{35}$Cl were used to verify the operation and data analysis procedures for the NPDGamma experiment which measured the parity-odd asymmetry in the angular distribution of gammas from polarized slow neutron capture on protons. △ Less

Submitted 22 July, 2022; originally announced July 2022.

Supernova Dust Evolution Probed by Deep-sea 60Fe Time History

Authors: Adrienne F. Ertel, Brian J. Fry, Brian D. Fields, John Ellis

Abstract: There is a wealth of data on live, undecayed 60Fe ($t_{1/2} = 2.6 \ \rm Myr$) in deep-sea deposits, the lunar regolith, cosmic rays, and Antarctic snow, which is interpreted as originating from the recent explosions of at least two near-Earth supernovae. We use the 60Fe profiles in deep-sea sediments to estimate the timescale of supernova debris deposition beginning $\sim 3$ Myr ago. The available… ▽ More There is a wealth of data on live, undecayed 60Fe ($t_{1/2} = 2.6 \ \rm Myr$) in deep-sea deposits, the lunar regolith, cosmic rays, and Antarctic snow, which is interpreted as originating from the recent explosions of at least two near-Earth supernovae. We use the 60Fe profiles in deep-sea sediments to estimate the timescale of supernova debris deposition beginning $\sim 3$ Myr ago. The available data admits a variety of different profile functions, but in all cases the best-fit 60Fe pulse durations are $>1.6$ Myr when all the data is combined. This timescale far exceeds the $\lesssim 0.1$ Myr pulse that would be expected if 60Fe was entrained in the supernova blast wave plasma. We interpret the long signal duration as evidence that 60Fe arrives in the form of supernova dust, whose dynamics are separate from but coupled to the evolution of the blast plasma. In this framework, the $>1.6$ Myr is that for dust stopping due to drag forces. This scenario is consistent with the simulations in Fry et. al (2020), where the dust is magnetically trapped in supernova remnants and thereby confined around regions of the remnant dominated by supernova ejects, where magnetic fields are low. This picture fits naturally with models of cosmic-ray injection of refractory elements as sputtered supernova dust grains and implies that the recent 60Fe detections in cosmic rays complement the fragments of grains that survived to arrive on the Earth and Moon. Finally, we present possible tests for this scenario. △ Less

Submitted 17 April, 2023; v1 submitted 13 June, 2022; originally announced June 2022.

Comments: 42 pages, 14 figures, matches version to appear in ApJ. Figures updated

Report number: KCL-PH-TH/2022-27, CERN-TH-2022-084

Projected Sensitivity of DMRadio-m$^3$: A Search for the QCD Axion Below $1\,μ$eV

Authors: DMRadio Collaboration, L. Brouwer, S. Chaudhuri, H. -M. Cho, J. Corbin, W. Craddock, C. S. Dawson, A. Droster, J. W. Foster, J. T. Fry, P. W. Graham, R. Henning, K. D. Irwin, F. Kadribasic, Y. Kahn, A. Keller, R. Kolevatov, S. Kuenstner, A. F. Leder, D. Li, J. L. Ouellet, K. Pappas, A. Phipps, N. M. Rapidis, B. R. Safdi , et al. (9 additional authors not shown)

Abstract: The QCD axion is one of the most compelling candidates to explain the dark matter abundance of the universe. With its extremely small mass ($\ll 1\,\mathrm{eV}/c^2$), axion dark matter interacts as a classical field rather than a particle. Its coupling to photons leads to a modification of Maxwell's equations that can be measured with extremely sensitive readout circuits. DMRadio-m$^3$ is a next-g… ▽ More The QCD axion is one of the most compelling candidates to explain the dark matter abundance of the universe. With its extremely small mass ($\ll 1\,\mathrm{eV}/c^2$), axion dark matter interacts as a classical field rather than a particle. Its coupling to photons leads to a modification of Maxwell's equations that can be measured with extremely sensitive readout circuits. DMRadio-m$^3$ is a next-generation search for axion dark matter below $1\,μ$eV using a $>4$ T static magnetic field, a coaxial inductive pickup, a tunable LC resonator, and a DC-SQUID readout. It is designed to search for QCD axion dark matter over the range $20\,\mathrm{neV}\lesssim m_ac^2\lesssim 800\,\mathrm{neV}$ ($5\,\mathrm{MHz}<ν<200\,\mathrm{MHz}$). The primary science goal aims to achieve DFSZ sensitivity above $m_ac^2\approx 120$ neV (30 MHz), with a secondary science goal of probing KSVZ axions down to $m_ac^2\approx40\,\mathrm{neV}$ (10 MHz). △ Less

Submitted 8 December, 2022; v1 submitted 28 April, 2022; originally announced April 2022.

Comments: 8 pages, 4 figures. Updated to fix small errors and correct acknowledgements. Updated title and notational clarifications

M5-branes wrapped on four-dimensional orbifolds

Authors: K. C. Matthew Cheung, Jacob H. T. Fry, Jerome P. Gauntlett, James Sparks

Abstract: We construct supersymmetric $AdS_3$ solutions of $D=11$ supergravity, dual to $d=2$, $\mathcal{N}=(0,2)$ SCFTs, that are associated with M5-branes wrapping two different four-dimensional orbifolds. In one case the orbifold is a spindle fibred over another spindle, while in the other it is a spindle fibred over a Riemann surface with genus $g>1$. We show that the central charges of the $d=2$ SCFTs… ▽ More We construct supersymmetric $AdS_3$ solutions of $D=11$ supergravity, dual to $d=2$, $\mathcal{N}=(0,2)$ SCFTs, that are associated with M5-branes wrapping two different four-dimensional orbifolds. In one case the orbifold is a spindle fibred over another spindle, while in the other it is a spindle fibred over a Riemann surface with genus $g>1$. We show that the central charges of the $d=2$ SCFTs calculated from the gravity solutions agree with field theory computations using anomaly polynomials. The new $D=11$ solutions are obtained after constructing a new consistent Kaluza-Klein truncation of maximal $D=7$ gauged supergravity reduced on a spindle down to $D=5$ minimal gauged supergravity. △ Less

Submitted 5 August, 2022; v1 submitted 6 April, 2022; originally announced April 2022.

Comments: 37 pages. Very minor changes. Published version

Report number: Imperial/TP/2022/JG/01

Axion Dark Matter

Authors: C. B. Adams, N. Aggarwal, A. Agrawal, R. Balafendiev, C. Bartram, M. Baryakhtar, H. Bekker, P. Belov, K. K. Berggren, A. Berlin, C. Boutan, D. Bowring, D. Budker, A. Caldwell, P. Carenza, G. Carosi, R. Cervantes, S. S. Chakrabarty, S. Chaudhuri, T. Y. Chen, S. Cheong, A. Chou, R. T. Co, J. Conrad, D. Croon , et al. (130 additional authors not shown)

Abstract: Axions are well-motivated dark matter candidates with simple cosmological production mechanisms. They were originally introduced to solve the strong CP problem, but also arise in a wide range of extensions to the Standard Model. This Snowmass white paper summarizes axion phenomenology and outlines next-generation laboratory experiments proposed to detect axion dark matter. There are vibrant synerg… ▽ More Axions are well-motivated dark matter candidates with simple cosmological production mechanisms. They were originally introduced to solve the strong CP problem, but also arise in a wide range of extensions to the Standard Model. This Snowmass white paper summarizes axion phenomenology and outlines next-generation laboratory experiments proposed to detect axion dark matter. There are vibrant synergies with astrophysical searches and advances in instrumentation including quantum-enabled readout, high-Q resonators and cavities and large high-field magnets. This white paper outlines a clear roadmap to discovery, and shows that the US is well-positioned to be at the forefront of the search for axion dark matter in the coming decade. △ Less

Submitted 29 March, 2023; v1 submitted 28 March, 2022; originally announced March 2022.

Comments: restore and expand author list

New Horizons: Scalar and Vector Ultralight Dark Matter

Authors: D. Antypas, A. Banerjee, C. Bartram, M. Baryakhtar, J. Betz, J. J. Bollinger, C. Boutan, D. Bowring, D. Budker, D. Carney, G. Carosi, S. Chaudhuri, S. Cheong, A. Chou, M. D. Chowdhury, R. T. Co, J. R. Crespo López-Urrutia, M. Demarteau, N. DePorzio, A. V. Derbin, T. Deshpande, M. D. Chowdhury, L. Di Luzio, A. Diaz-Morcillo, J. M. Doyle , et al. (104 additional authors not shown)

Abstract: The last decade has seen unprecedented effort in dark matter model building at all mass scales coupled with the design of numerous new detection strategies. Transformative advances in quantum technologies have led to a plethora of new high-precision quantum sensors and dark matter detection strategies for ultralight ($<10\,$eV) bosonic dark matter that can be described by an oscillating classical,… ▽ More The last decade has seen unprecedented effort in dark matter model building at all mass scales coupled with the design of numerous new detection strategies. Transformative advances in quantum technologies have led to a plethora of new high-precision quantum sensors and dark matter detection strategies for ultralight ($<10\,$eV) bosonic dark matter that can be described by an oscillating classical, largely coherent field. This white paper focuses on searches for wavelike scalar and vector dark matter candidates. △ Less

Submitted 28 March, 2022; originally announced March 2022.

Comments: Snowmass 2021 White Paper

Introducing DMRadio-GUT, a search for GUT-scale QCD axions

Authors: L. Brouwer, S. Chaudhuri, H. -M. Cho, J. Corbin, C. S. Dawson, A. Droster, J. W. Foster, J. T. Fry, P. W. Graham, R. Henning, K. D. Irwin, F. Kadribasic, Y. Kahn, A. Keller, R. Kolevatov, S. Kuenstner, A. F. Leder, D. Li, J. L. Ouellet, K. M. W. Pappas, A. Phipps, N. M. Rapidis, B. R. Safdi, C. P. Salemi, M. Simanovskaia , et al. (7 additional authors not shown)

Abstract: The QCD axion is a leading dark matter candidate that emerges as part of the solution to the strong CP problem in the Standard Model. The coupling of the axion to photons is the most common experimental probe, but much parameter space remains unexplored. The coupling of the QCD axion to the Standard Model scales linearly with the axion mass; therefore, the highly-motivated region 0.4-120 neV, corr… ▽ More The QCD axion is a leading dark matter candidate that emerges as part of the solution to the strong CP problem in the Standard Model. The coupling of the axion to photons is the most common experimental probe, but much parameter space remains unexplored. The coupling of the QCD axion to the Standard Model scales linearly with the axion mass; therefore, the highly-motivated region 0.4-120 neV, corresponding to a GUT-scale axion, is particularly difficult to reach. This paper presents the design requirements for a definitive search for GUT-scale axions and reviews the technological advances needed to enable this program. △ Less

Submitted 21 March, 2022; originally announced March 2022.

Comments: 16 pages, 4 figures

Journal ref: Phys.Rev.D 106 (2022) 11, 112003

Combining Individual and Joint Networking Behavior for Intelligent IoT Analytics

Authors: Jeya Vikranth Jeyakumar, Ludmila Cherkasova, Saina Lajevardi, Moray Allan, Yue Zhao, John Fry, Mani Srivastava

Abstract: The IoT vision of a trillion connected devices over the next decade requires reliable end-to-end connectivity and automated device management platforms. While we have seen successful efforts for maintaining small IoT testbeds, there are multiple challenges for the efficient management of large-scale device deployments. With Industrial IoT, incorporating millions of devices, traditional management… ▽ More The IoT vision of a trillion connected devices over the next decade requires reliable end-to-end connectivity and automated device management platforms. While we have seen successful efforts for maintaining small IoT testbeds, there are multiple challenges for the efficient management of large-scale device deployments. With Industrial IoT, incorporating millions of devices, traditional management methods do not scale well. In this work, we address these challenges by designing a set of novel machine learning techniques, which form a foundation of a new tool, it IoTelligent, for IoT device management, using traffic characteristics obtained at the network level. The design of our tool is driven by the analysis of 1-year long networking data, collected from 350 companies with IoT deployments. The exploratory analysis of this data reveals that IoT environments follow the famous Pareto principle, such as: (i) 10% of the companies in the dataset contribute to 90% of the entire traffic; (ii) 7% of all the companies in the set own 90% of all the devices. We designed and evaluated CNN, LSTM, and Convolutional LSTM models for demand forecasting, with a conclusion of the Convolutional LSTM model being the best. However, maintaining and updating individual company models is expensive. In this work, we design a novel, scalable approach, where a general demand forecasting model is built using the combined data of all the companies with a normalization factor. Moreover, we introduce a novel technique for device management, based on autoencoders. They automatically extract relevant device features to identify device groups with similar behavior to flag anomalous devices. △ Less

Submitted 6 March, 2022; originally announced March 2022.

Journal ref: InInternational Conference on Internet of Things 2020 Sep 18 (pp. 45-62). Springer, Cham

Clar's goblet on graphene: field modulated charge transfer in a hydrocarbon heterostructure

Authors: Adam V. Bruce, Shuanglong Liu, James N. Fry, Hai-Ping Cheng

Abstract: In certain configurations, the aromatic properties of benzene ring structured molecules allow for unpaired, reactive valence electrons (known as radicals). Clar's goblets are such molecules. With an even number of unpaired radicals, these nanographenes are topologically frustrated hydrocarbons in which pi-bonding network and topology of edges give rise to the magnetism. Clar's goblets are therefor… ▽ More In certain configurations, the aromatic properties of benzene ring structured molecules allow for unpaired, reactive valence electrons (known as radicals). Clar's goblets are such molecules. With an even number of unpaired radicals, these nanographenes are topologically frustrated hydrocarbons in which pi-bonding network and topology of edges give rise to the magnetism. Clar's goblets are therefore valued as prospective qubits provided they can be modulated between magnetic states. Using first principles DFT, we demonstrate the effects of adsorption on both molecule and substrate in a graphene-Clar's goblet heterostructure. We look at the energy difference bewteen FM and AFM states of the system and discuss underlying physical and chemical mechanisms in reference to the highest occupied molecular orbital (HOMO) and second HOMO (HOMO-1). We find that the HOMO of the molecule in the FM state is right at the Fermi surface, which leads to the hybridization between molecular state and the graphene state near the Dirac point. Furthermore, we investigate qualitative changes in charge realignment and magnetic state under variable electric field. Transitions from FM to AFM and back to FM states are observed. △ Less

Submitted 26 January, 2022; originally announced January 2022.

Comments: 10 pages, 8 figures

Insights to negative differential resistance in \texorpdfstring{MoS\textsubscript{2}}{MoS2} Esaki diodes: a first-principles perspective

Authors: Adam V. Bruce, Shuanglong Liu, James N. Fry, Hai-Ping Cheng

Abstract: \ce{MoS_2} is a two dimensional material with a band gap depending on the number of layers and tunable by an external electric field. The experimentally observed intralayer band-to-band tunneling and interlayer band-to-band tunneling in this material present an opportunity for new electronic applications in tunnel field effect transistors. However, such a widely accepted concept has never been sup… ▽ More \ce{MoS_2} is a two dimensional material with a band gap depending on the number of layers and tunable by an external electric field. The experimentally observed intralayer band-to-band tunneling and interlayer band-to-band tunneling in this material present an opportunity for new electronic applications in tunnel field effect transistors. However, such a widely accepted concept has never been supported up by theoretical investigations based on first principles. In this work, using density functional theory, in conjunction with non-equilibrilibrium Green's function techniques and our electric field gating method, enabled by a large-scale computational approach, we study the relation between band alignment and transmission in planar and side-stack \ce{MoS_2} $p$-$i$-$n$ junction configurations. We demonstrate the presence of negative differential resistance for both in-plane and interlayer current, a staple characteristic of tunnel diode junctions, and analyze the physical origin of such an effect. Electrostatic potentials, the van der Waals barrier, and complex band analysis are also examined for a thorough understanding of Esaki Diodes. △ Less

Submitted 6 January, 2022; originally announced January 2022.

Comments: 8 pages, 8 figures

Journal ref: Phys. Rev. B 102, 115415 (2020)

Proposed Lunar Measurements of $r$-Process Radioisotopes to Distinguish Origin of Deep-sea 244Pu

Authors: Xilu Wang, Adam M. Clark, John Ellis, Adrienne F. Ertel, Brian D. Fields, Brian J. Fry, Zhenghai Liu, Jesse A. Miller, Rebecca Surman

Abstract: 244Pu has recently been discovered in deep-sea deposits spanning the past 10 Myr, a period that includes two 60Fe pulses from nearby supernovae. 244Pu is among the heaviest $r$-process products, and we consider whether it was created in the supernovae, which is disfavored by nucleosynthesis simulations, or in an earlier kilonova event that seeded 244Pu in the nearby interstellar medium that was su… ▽ More 244Pu has recently been discovered in deep-sea deposits spanning the past 10 Myr, a period that includes two 60Fe pulses from nearby supernovae. 244Pu is among the heaviest $r$-process products, and we consider whether it was created in the supernovae, which is disfavored by nucleosynthesis simulations, or in an earlier kilonova event that seeded 244Pu in the nearby interstellar medium that was subsequently swept up by the supernova debris. We discuss how these possibilities can be probed by measuring 244Pu and other $r$-process radioisotopes such as 129I and 182Hf, both in lunar regolith samples returned to Earth by missions such as Chang'e and Artemis, and in deep-sea deposits. △ Less

Submitted 29 March, 2023; v1 submitted 17 December, 2021; originally announced December 2021.

Comments: 19 pages, 4 figures, 2 tables, v3 matches version to appear in ApJ

Report number: KCL-PH-TH/2021-91, CERN-TH-2021-208, N3AS-21-017

Journal ref: The Astrophysical Journal, 2023, Volume 948, Issue 2, id.113, 13 pp

Measurement of the Positive Muon Anomalous Magnetic Moment to 0.46 ppm

Authors: B. Abi, T. Albahri, S. Al-Kilani, D. Allspach, L. P. Alonzi, A. Anastasi, A. Anisenkov, F. Azfar, K. Badgley, S. Baeßler, I. Bailey, V. A. Baranov, E. Barlas-Yucel, T. Barrett, E. Barzi, A. Basti, F. Bedeschi, A. Behnke, M. Berz, M. Bhattacharya, H. P. Binney, R. Bjorkquist, P. Bloom, J. Bono, E. Bottalico , et al. (212 additional authors not shown)

Abstract: We present the first results of the Fermilab Muon g-2 Experiment for the positive muon magnetic anomaly $a_μ\equiv (g_μ-2)/2$. The anomaly is determined from the precision measurements of two angular frequencies. Intensity variation of high-energy positrons from muon decays directly encodes the difference frequency $ω_a$ between the spin-precession and cyclotron frequencies for polarized muons in… ▽ More We present the first results of the Fermilab Muon g-2 Experiment for the positive muon magnetic anomaly $a_μ\equiv (g_μ-2)/2$. The anomaly is determined from the precision measurements of two angular frequencies. Intensity variation of high-energy positrons from muon decays directly encodes the difference frequency $ω_a$ between the spin-precession and cyclotron frequencies for polarized muons in a magnetic storage ring. The storage ring magnetic field is measured using nuclear magnetic resonance probes calibrated in terms of the equivalent proton spin precession frequency ${\tildeω'^{}_p}$ in a spherical water sample at 34.7$^{\circ}$C. The ratio $ω_a / {\tildeω'^{}_p}$, together with known fundamental constants, determines $a_μ({\rm FNAL}) = 116\,592\,040(54)\times 10^{-11}$ (0.46\,ppm). The result is 3.3 standard deviations greater than the standard model prediction and is in excellent agreement with the previous Brookhaven National Laboratory (BNL) E821 measurement. After combination with previous measurements of both $μ^+$ and $μ^-$, the new experimental average of $a_μ({\rm Exp}) = 116\,592\,061(41)\times 10^{-11}$ (0.35\,ppm) increases the tension between experiment and theory to 4.2 standard deviations △ Less

Submitted 7 April, 2021; originally announced April 2021.

Comments: 10 pages; 4 figures

Report number: FERMILAB-PUB-21-132-E

Journal ref: Phys. Rev. Lett. 126, 141801 (2021)

Measurement of the anomalous precession frequency of the muon in the Fermilab Muon g-2 experiment

Authors: T. Albahri, A. Anastasi, A. Anisenkov, K. Badgley, S. Baeßler, I. Bailey, V. A. Baranov, E. Barlas-Yucel, T. Barrett, A. Basti, F. Bedeschi, M. Berz, M. Bhattacharya, H. P. Binney, P. Bloom, J. Bono, E. Bottalico, T. Bowcock, G. Cantatore, R. M. Carey, B. C. K. Casey, D. Cauz, R. Chakraborty, S. P. Chang, A. Chapelain , et al. (153 additional authors not shown)

Abstract: The Muon g-2 Experiment at Fermi National Accelerator Laboratory (FNAL) has measured the muon anomalous precession frequency $ω_a$ to an uncertainty of 434 parts per billion (ppb), statistical, and 56 ppb, systematic, with data collected in four storage ring configurations during its first physics run in 2018. When combined with a precision measurement of the magnetic field of the experiment's muo… ▽ More The Muon g-2 Experiment at Fermi National Accelerator Laboratory (FNAL) has measured the muon anomalous precession frequency $ω_a$ to an uncertainty of 434 parts per billion (ppb), statistical, and 56 ppb, systematic, with data collected in four storage ring configurations during its first physics run in 2018. When combined with a precision measurement of the magnetic field of the experiment's muon storage ring, the precession frequency measurement determines a muon magnetic anomaly of $a_μ({\rm FNAL}) = 116\,592\,040(54) \times 10^{-11}$ (0.46 ppm). This article describes the multiple techniques employed in the reconstruction, analysis and fitting of the data to measure the precession frequency. It also presents the averaging of the results from the eleven separate determinations of ω_a, and the systematic uncertainties on the result. △ Less

Submitted 7 April, 2021; originally announced April 2021.

Comments: 29 pages, 19 figures. Published in Physical Review D

Report number: FERMILAB-PUB-21-183-E

Journal ref: Phys. Rev. D 103, 072002 (2021)

Beam dynamics corrections to the Run-1 measurement of the muon anomalous magnetic moment at Fermilab

Authors: T. Albahri, A. Anastasi, K. Badgley, S. Baeßler, I. Bailey, V. A. Baranov, E. Barlas-Yucel, T. Barrett, F. Bedeschi, M. Berz, M. Bhattacharya, H. P. Binney, P. Bloom, J. Bono, E. Bottalico, T. Bowcock, G. Cantatore, R. M. Carey, B. C. K. Casey, D. Cauz, R. Chakraborty, S. P. Chang, A. Chapelain, S. Charity, R. Chislett , et al. (152 additional authors not shown)

Abstract: This paper presents the beam dynamics systematic corrections and their uncertainties for the Run-1 data set of the Fermilab Muon g-2 Experiment. Two corrections to the measured muon precession frequency $ω_a^m$ are associated with well-known effects owing to the use of electrostatic quadrupole (ESQ) vertical focusing in the storage ring. An average vertically oriented motional magnetic field is fe… ▽ More This paper presents the beam dynamics systematic corrections and their uncertainties for the Run-1 data set of the Fermilab Muon g-2 Experiment. Two corrections to the measured muon precession frequency $ω_a^m$ are associated with well-known effects owing to the use of electrostatic quadrupole (ESQ) vertical focusing in the storage ring. An average vertically oriented motional magnetic field is felt by relativistic muons passing transversely through the radial electric field components created by the ESQ system. The correction depends on the stored momentum distribution and the tunes of the ring, which has relatively weak vertical focusing. Vertical betatron motions imply that the muons do not orbit the ring in a plane exactly orthogonal to the vertical magnetic field direction. A correction is necessary to account for an average pitch angle associated with their trajectories. A third small correction is necessary because muons that escape the ring during the storage time are slightly biased in initial spin phase compared to the parent distribution. Finally, because two high-voltage resistors in the ESQ network had longer than designed RC time constants, the vertical and horizontal centroids and envelopes of the stored muon beam drifted slightly, but coherently, during each storage ring fill. This led to the discovery of an important phase-acceptance relationship that requires a correction. The sum of the corrections to $ω_a^m$ is 0.50 $\pm$ 0.09 ppm; the uncertainty is small compared to the 0.43 ppm statistical precision of $ω_a^m$. △ Less

Submitted 23 April, 2021; v1 submitted 7 April, 2021; originally announced April 2021.

Comments: 35 pages, 29 figures. Accepted by Phys. Rev. Accel. Beams

Report number: FERMILAB-PUB-21-133-E

Journal ref: Phys. Rev. Accel. Beams 24, 044002 (2021)

The Logical Options Framework

Authors: Brandon Araki, Xiao Li, Kiran Vodrahalli, Jonathan DeCastro, Micah J. Fry, Daniela Rus

Abstract: Learning composable policies for environments with complex rules and tasks is a challenging problem. We introduce a hierarchical reinforcement learning framework called the Logical Options Framework (LOF) that learns policies that are satisfying, optimal, and composable. LOF efficiently learns policies that satisfy tasks by representing the task as an automaton and integrating it into learning and… ▽ More Learning composable policies for environments with complex rules and tasks is a challenging problem. We introduce a hierarchical reinforcement learning framework called the Logical Options Framework (LOF) that learns policies that are satisfying, optimal, and composable. LOF efficiently learns policies that satisfy tasks by representing the task as an automaton and integrating it into learning and planning. We provide and prove conditions under which LOF will learn satisfying, optimal policies. And lastly, we show how LOF's learned policies can be composed to satisfy unseen tasks with only 10-50 retraining steps. We evaluate LOF on four tasks in discrete and continuous domains, including a 3D pick-and-place environment. △ Less

Submitted 24 February, 2021; originally announced February 2021.

Comments: 23 pages, 19 figures

ACM Class: I.2.9; I.2.6; G.3; I.5.1

Multiple Control of Few-layer Janus MoSSe Systems

Authors: Shuanglong Liu, James N. Fry, Hai-Ping Cheng

Abstract: In this computational work based on density functional theory we study the electronic and electron transport properties of asymmetric multi-layer MoSSe junctions, known as Janus junctions. Focusing on 4-layer systems, we investigate the influence of electric field, electrostatic doping, strain, and interlayer stacking on the electronic structure. We discover that a metal to semiconductor transitio… ▽ More In this computational work based on density functional theory we study the electronic and electron transport properties of asymmetric multi-layer MoSSe junctions, known as Janus junctions. Focusing on 4-layer systems, we investigate the influence of electric field, electrostatic doping, strain, and interlayer stacking on the electronic structure. We discover that a metal to semiconductor transition can be induced by an out-of-plane electric field. The critical electric field for such a transition can be reduced by in-plane biaxial compressive strain. Due to an intrinsic electric field, a 4-layer MoSSe can rectify out-of-plane electric current. The rectifying ratio reaches 34.1 in a model junction Zr/4-layer MoSSe/Zr. This ratio can be further enhanced by increasing the number of MoSSe layers. In addition, we show a drastic sudden vertical compression of 4-layer MoSSe due to in-plane biaxial tensile strain, indicating a second phase transition. Furthermore, an odd-even effect on electron transmission at the Fermi energy for Zr/$n$-layer MoSSe/Zr junctions with $n=1, \, 2,\, 3, \,\dots,\, 10$ is observed. These findings reveal the richness of physics in this asymmetric system and strongly suggest that the properties of 4-layer MoSSe are highly tunable, thus providing a guide to future experiments relating materials research and nanoelectronics. △ Less

Submitted 17 November, 2020; originally announced November 2020.

Journal ref: Phys. Rev. Materials 5, 064007 (2021)

Single-Molecule Magnet Mn$_{12}$ on GaAs-supported Graphene: Gate Field Effects From First Principles

Authors: Shuanglong Liu, Maher Yazback, James N. Fry, Xiao-Guang Zhang, Hai-Ping Cheng

Abstract: We study gate field effects on the Mn$_{12}$O$_{12}$(COOH)$_{16}$(H$_2$O)$_4$ | graphene | GaAs heterostructure via first-principles calculations. We find that under moderate doping levels electrons can be added to but not taken from the single-molecule magnet Mn$_{12}$O$_{12}$(COOH)$_{16}$(H$_2$O)$_4$ (Mn$_{12}$). The magnetic anisotropy energy (MAE) of Mn$_{12}$ decreases as the electron doping… ▽ More We study gate field effects on the Mn$_{12}$O$_{12}$(COOH)$_{16}$(H$_2$O)$_4$ | graphene | GaAs heterostructure via first-principles calculations. We find that under moderate doping levels electrons can be added to but not taken from the single-molecule magnet Mn$_{12}$O$_{12}$(COOH)$_{16}$(H$_2$O)$_4$ (Mn$_{12}$). The magnetic anisotropy energy (MAE) of Mn$_{12}$ decreases as the electron doping level increases, due to electron transfer from graphene to Mn$_{12}$ and change in the band alignment between Mn$_{12}$ and graphene. At an electron doping level of $-5.00 \times 10^{13}\, \textrm{cm}^{-2}$, the MAE decreases by about 18% compared with zero doping. The band alignment between graphene and GaAs is more sensitive to electron doping than to hole doping since the valence band of GaAs is close to the Fermi level. The GaAs substrate induces a small bandgap in the supported graphene under the zero gate field and a nearly strain-free configuration. Finally, we propose a vertical tunnel junction for probing the gate dependence of MAE via electron transport measurements. △ Less

Submitted 3 January, 2022; v1 submitted 15 November, 2020; originally announced November 2020.

Journal ref: Phys. Rev. B 105, 035401 (2022)

Supernova Triggers for End-Devonian Extinctions

Authors: Brian D. Fields, Adrian L. Melott, John Ellis, Adrienne F. Ertel, Brian J. Fry, Bruce S. Lieberman, Zhenghai Liu, Jesse A. Miller, Brian C. Thomas

Abstract: The Late Devonian was a protracted period of low speciation resulting in biodiversity decline, culminating in extinction events near the Devonian-Carboniferous boundary. Recent evidence indicates that the final extinction event may have coincided with a dramatic drop in stratospheric ozone, possibly due to a global temperature rise. Here we study an alternative possible cause for the postulated oz… ▽ More The Late Devonian was a protracted period of low speciation resulting in biodiversity decline, culminating in extinction events near the Devonian-Carboniferous boundary. Recent evidence indicates that the final extinction event may have coincided with a dramatic drop in stratospheric ozone, possibly due to a global temperature rise. Here we study an alternative possible cause for the postulated ozone drop: a nearby supernova explosion that could inflict damage by accelerating cosmic rays that can deliver ionizing radiation for up to $\sim 100$ kyr. We therefore propose that the end-Devonian extinctions were triggered by supernova explosions at $\sim 20$ pc, somewhat beyond the "kill distance" that would have precipitated a full mass extinction. Such nearby supernovae are likely due to core-collapses of massive stars; these are concentrated in the thin Galactic disk where the Sun resides. Detecting either of the long-lived radioisotopes Sm-146 or Pu-244 in one or more end-Devonian extinction strata would confirm a supernova origin, point to the core-collapse explosion of a massive star, and probe supernova nucleosythesis. Other possible tests of the supernova hypothesis are discussed. △ Less

Submitted 25 August, 2020; v1 submitted 3 July, 2020; originally announced July 2020.

Comments: 3 pages, no figures. Matches published version. Creative Commons CC BY-NC-ND license

Journal ref: PNAS 117, 35, 21008-21010 (2020)

First-principles study of magnetism and electric field effects in 2D systems

Authors: Hai-Ping Cheng, Shuanglong Liu, Xiao Chen, Long Zhang, James N Fry

Abstract: This review article provides a bird's-eye view of what first-principles based methods can contribute to next-generation device design and simulation. After a brief overview of methods and capabilities in the area, we focus on published work by our group since 2015 and current work on $\textrm{CrI}_3$. We introduce both single- and dual-gate models in the framework of density functional theory and… ▽ More This review article provides a bird's-eye view of what first-principles based methods can contribute to next-generation device design and simulation. After a brief overview of methods and capabilities in the area, we focus on published work by our group since 2015 and current work on $\textrm{CrI}_3$. We introduce both single- and dual-gate models in the framework of density functional theory and the constrained random phase approximation in estimating the Hubbard $U$ for 2D systems vs. their 3D counterparts. A wide range of systems, including graphene-based heterogeneous systems, transition metal dichalcogenides, and topological insulators, and a rich array of physical phenomena, including the macroscopic origin of polarization, field effects on magnetic order, interface state resonance induced peak in transmission coefficients, spin filtration, etc., are covered. For $\textrm{CrI}_3$ we present our new results on bilayer systems such as the interplay between stacking and magnetic order, pressure dependence, and electric field induced magnetic phase transitions. We find that a bare bilayer $\textrm{CrI}_3$, graphene$\,|\,$bilayer $\textrm{CrI}_3\,|\,$graphene, $h$-BN$\,|\,$bilayer $\textrm{CrI}_3\,|\,h$-BN, and $h$-BN$\,|\,$bilayer $\textrm{CrI}_3\,|\,$graphene all have a different response at high field, while small field the difference is small except for graphene$\,|\,$bilayer $\textrm{CrI}_3\,|\,$graphene. We conclude with discussion of some ongoing work and work planned in the near future, with the inclusion of further method development and applications. △ Less

Submitted 8 June, 2020; originally announced June 2020.

First-principles calculation of gate-tunable ferromagnetism in magic-angle twisted bilayer graphene under pressure

Authors: Xiao Chen, Shuanglong Liu, James N Fry, Hai-Ping Cheng

Abstract: Magic-angle twisted bilayer graphene (MATBG) is notable as a highly tunable platform for investigating strongly correlated phenomena such as high-$T_c$ superconductivity and quantum spin liquids, due to easy control of doping level through gating and sensitive dependence of the magic angle on hydrostatic pressure. Experimental observations of correlated insulating states, unconventional supercondu… ▽ More Magic-angle twisted bilayer graphene (MATBG) is notable as a highly tunable platform for investigating strongly correlated phenomena such as high-$T_c$ superconductivity and quantum spin liquids, due to easy control of doping level through gating and sensitive dependence of the magic angle on hydrostatic pressure. Experimental observations of correlated insulating states, unconventional superconductivity and ferromagnetism in MATBG indicate that this system exhibits rich exotic phases. In this work, using density functional theory calculations in conjunction with the effective screening medium method, we find the MATBG under pressure at a twisting angle of $2.88\unicode{xb0}$ and simulate how its electronic states evolve when doping level and out-of-plane electric field are gate-tuned. Our calculations show that, at doping levels between two electrons and four holes per moiré unit cell, a ferromagnetic solution with spin density localized at AA stacking sites is lower in energy than the nonmagnetic solution. The magnetic moment of this ferromagnetic state decreases with both electron and hole doping and vanishes at four electrons/holes doped per moiré unit cell. Hybridization between the flat bands at the Fermi level and the surrounding dispersive bands can take place at finite doping. Moreover, upon increasing the out-of-plane electric field at zero doping, a transition from the ferromagnetic state to the nonmagnetic one is seen. We also analyze the interlayer bonding character due to the flat bands via Wannier functions. Finally, we report trivial band topology of the flat bands in the ferromagnetic state at a certain doping level. △ Less

Submitted 3 June, 2020; originally announced June 2020.

Spin-imbalanced ultracold Fermi gases in a two-dimensional array of tubes

Authors: Bhuvanesh Sundar, Jacob A. Fry, Melissa C. Revelle, Randall G. Hulet, Kaden R. A. Hazzard

Abstract: Motivated by a recent experiment [Revelle et al. Phys. Rev. Lett. 117, 235301 (2016)] that characterized the one- to three-dimensional crossover in a spin-imbalanced ultracold gas of $^6$Li atoms trapped in a two-dimensional array of tunnel-coupled tubes, we calculate the phase diagram for this system using Hartree-Fock Bogoliubov-de Gennes mean-field theory, and compare the results with experimen… ▽ More Motivated by a recent experiment [Revelle et al. Phys. Rev. Lett. 117, 235301 (2016)] that characterized the one- to three-dimensional crossover in a spin-imbalanced ultracold gas of $^6$Li atoms trapped in a two-dimensional array of tunnel-coupled tubes, we calculate the phase diagram for this system using Hartree-Fock Bogoliubov-de Gennes mean-field theory, and compare the results with experimental data. Mean-field theory predicts fully spin-polarized normal, partially spin-polarized normal, spin-polarized superfluid, and spin-balanced superfluid phases in a homogeneous system. We use the local density approximation to obtain density profiles of the gas in a harmonic trap. We compare these calculations with experimental measurements in Revelle {\em et al.} as well as previously unpublished data. Our calculations qualitatively agree with experimentally-measured densities and coordinates of the phase boundaries in the trap, and quantitatively agree with experimental measurements at moderate-to-large polarizations. Our calculations also reproduce the experimentally-observed universal scaling of the phase boundaries for different scattering lengths at a fixed value of scaled inter-tube tunneling. However, our calculations have quantitative differences with experimental measurements at low polarization, and fail to capture important features of the one- to three-dimensional crossover observed in experiments. These suggest the important role of physics beyond-mean-field theory in the experiments. We expect that our numerical results will aid future experiments in narrowing the search for the FFLO phase. △ Less

Submitted 8 September, 2020; v1 submitted 4 May, 2020; originally announced May 2020.

Comments: 13 pages, 8 figures. Minor revisions; Conclusions unchanged

Journal ref: Phys. Rev. A 102, 033311 (2020)

Gate field effects on the topological insulator BiSbTeSe2 interface

Authors: Shuanglong Liu, Yang Xu, Yun-Peng Wang, Yong P. Chen, James N. Fry, Hai-Ping Cheng

Abstract: Interfaces between two topological insulators are of fundamental interest in condensed matter physics. Inspired by experimental efforts, we study interfacial processes between two slabs of BiSbTeSe2 (BSTS) via first principles calculations. Topological surface states are absent for the BSTS interface at its equilibrium separation, but our calculations show that they appear if the inter-slab distan… ▽ More Interfaces between two topological insulators are of fundamental interest in condensed matter physics. Inspired by experimental efforts, we study interfacial processes between two slabs of BiSbTeSe2 (BSTS) via first principles calculations. Topological surface states are absent for the BSTS interface at its equilibrium separation, but our calculations show that they appear if the inter-slab distance is greater than 6 Ang. More importantly, we find that topological interface states can be preserved by inserting two or more layers of hexagonal boron nitride between the two BSTS slabs. In experiments, the electric current tunneling through the interface is insensitive to back gate voltage when the bias voltage is small. Using a first-principles based method that allows us to simulate gate field, we show that at low bias the extra charge induced by a gate voltage resides on the surface that is closest to the gate electrode, leaving the interface almost undoped. This provides clues to understand the origin of the observed insensitivity of transport properties to back voltage at low bias. Our study resolves a few questions raised in experiment, which does not yet offer a clear correlation between microscopic physics and transport data. We provide a road map for the design of vertical tunneling junctions involving the interface between two topological insulators. △ Less

Submitted 8 June, 2020; v1 submitted 15 October, 2019; originally announced October 2019.