Showing 1–50 of 190 results for author: Thomas, J

Low-loss phononic integrated circuits based on a silicon nitride-lithium niobate platform

Authors: Jun Ji, Joseph G Thomas, Zichen Xi, Ruxuan Liu, Kinson Fang, Yuan Qin, Andreas Beling, Xu Yi, Yizheng Zhu, Linbo Shao

Abstract: Microwave-frequency acoustic waves in solids have emerged as a versatile platform for both classical and quantum applications. While phononic integrated devices and circuits are being developed on various material platforms, an ideal phononic integrated circuit (PnIC) platform should simultaneously support low-loss waveguide structures, high-quality-factor resonators, high-performance modulators,… ▽ More Microwave-frequency acoustic waves in solids have emerged as a versatile platform for both classical and quantum applications. While phononic integrated devices and circuits are being developed on various material platforms, an ideal phononic integrated circuit (PnIC) platform should simultaneously support low-loss waveguide structures, high-quality-factor resonators, high-performance modulators, and efficient electromechanical transducers. Here, we establish a low-loss gigahertz-frequency PnIC platform based on patterned thin-film silicon nitride (SiN) on lithium niobate (LN) substrate. We develop low-loss PnIC building blocks including waveguides, directional couplers, and high-quality-factor (high-Q) ring resonators. As an application, we demonstrate a 1-GHz phononic oscillator based on a ring resonator, reaching a low phase noise of -159.0 dBc/Hz at a 100-kHz offset frequency. Our low-loss PnICs could meet the requirements in microwave acoustics, quantum phononics, and integrated hybrid systems combining phonons, photons, superconducting qubits, and solid-state defects. △ Less

Submitted 29 March, 2026; originally announced March 2026.

Resonance-enhanced integrated acousto-optic beam steering

Authors: Yue Yu, Qixuan Lin, Shucheng Fang, Joseph G. Thomas, Yibing Zhou, Zichen Xi, Jun Ji, Yizheng Zhu, Linbo Shao, Bingzhao Li, Mo Li

Abstract: Optical beam steering is a key technology for free-space optical communication, sensing, and imaging. Mechanical beam steering systems suffer from limited scanning speed and bulky form factors, while existing solid-state solutions rely on pixelated synthetic aperture that requires complex fabrication and control architectures. Integrated acousto-optic beam steering (AOBS) is an emerging technology… ▽ More Optical beam steering is a key technology for free-space optical communication, sensing, and imaging. Mechanical beam steering systems suffer from limited scanning speed and bulky form factors, while existing solid-state solutions rely on pixelated synthetic aperture that requires complex fabrication and control architectures. Integrated acousto-optic beam steering (AOBS) is an emerging technology that enables continuous one-dimensional beam steering using integrated acoustic transducers and fixed-wavelength laser sources. Here, we integrate AOBS with an optical ring resonator on the same thin-film lithium niobate (TFLN) platform to significantly enhance beam steering efficiency and system functionality. The resulting device achieves a resonance-enhanced beam steering efficiency of up to 20% over a 18 degrees field of view. Moreover, by leveraging integrated electro-optic control, we dynamically lock the ring-resonator's resonance to a chirped laser frequency, enabling frequency-modulated continuous-wave (FMCW) LiDAR operation. By combining lithium niobate's piezoelectric and electro-optic properties, this work establishes a compact, efficient, and scalable beam-steering platform with co-integrated acousto-optic modulation and electro-optic control for multifunctional applications. △ Less

Submitted 18 March, 2026; originally announced March 2026.

Design and implementation of a modular laser system for AMO experiments

Authors: Klara Theophilo, Scott J Thomas, Georgina Croft, Yashna N D Lekhai, Alexander Owens, Daisy R H Smith, Silpa Muralidharan, Cameron Deans

Abstract: Robust laser delivery and stabilization are key components in atom-based quantum technologies, such as quantum computing. Moving these technologies towards product-like deployment requires scalable, compact, cost-effective, and upgradable modules. Here we describe laser systems consisting of application-flexible modules and demonstrate their performance by characterizing key metrics and by integra… ▽ More Robust laser delivery and stabilization are key components in atom-based quantum technologies, such as quantum computing. Moving these technologies towards product-like deployment requires scalable, compact, cost-effective, and upgradable modules. Here we describe laser systems consisting of application-flexible modules and demonstrate their performance by characterizing key metrics and by integration with ion trap systems. The laser system is confined to a single server rack and a compact locking station. Both are Class 1 laser products with fiber in-out and electronic control of the laser light. This is achieved through precision manufacture of optical boards that are designed to reduce the degrees of freedom, ease alignment, and increase the robustness to environmental factors. We present a range of 13 wavelengths from 375 nm to 1092 nm: efficiencies from laser source to ion trap range from 21 - 28%, with laser stabilization line widths below 1 MHz. △ Less

Submitted 24 March, 2026; v1 submitted 18 March, 2026; originally announced March 2026.

Comments: 10 pages, 16 figures

Volumetric effects in viscous flows in circular and annular tubes with wavy walls

Authors: Yisen Guo, John H. Thomas

Abstract: We point out that, in the usual way of specifying a sinusoidal waviness of the wall of a tube of circular cross section, in which the mean radius is kept constant, the interior volume of the tube increases with increasing wave amplitude. We compare this case with the case where the interior volume is kept constant by reducing the mean radius as the wave amplitude increases. We present and compare… ▽ More We point out that, in the usual way of specifying a sinusoidal waviness of the wall of a tube of circular cross section, in which the mean radius is kept constant, the interior volume of the tube increases with increasing wave amplitude. We compare this case with the case where the interior volume is kept constant by reducing the mean radius as the wave amplitude increases. We present and compare numerical results of these two cases for steady, pressure driven, laminar viscous flow in a tube with a stationary wavy wall, for both circular and annular tubes. The volume flow rate and the hydraulic resistance can differ in the two cases by as much as 10% for wave amplitudes as small as 20% of the mean radius and as much as 50% for larger wave amplitudes. For a circular tube, we derive a scaling law that relates the two cases based on dimensional analysis, allowing the behavior in the constant-volume case to be determined from that in the constant-mean-radius case. Additionally, we consider peristaltic pumping due to a moving sinusoidal wall wave and show that the volume-change effect is significant even at small wave amplitudes, and that the volume flow rates in the two cases can differ significantly, by as much as 50% as the wave amplitude approaches its maximum value. △ Less

Submitted 4 March, 2026; originally announced March 2026.

Bayesian identification of fibrous insulation thermal conductivity towards design of spacecraft thermal protection systems

Authors: Alex Alberts, Akshay Jacob Thomas, Kamran Daryabeigi, Ilias Bilionis

Abstract: The design of spacecraft thermal protection systems (TPS) requires accurate knowledge of thermal transport properties across wide ranges of temperature and pressure. For fibrous insulation, conventional measurement techniques in laboratory settings are typically limited to temperatures much lower than what is reached in atmosphere entry scenarios. Moreover, it is often the case that only temperatu… ▽ More The design of spacecraft thermal protection systems (TPS) requires accurate knowledge of thermal transport properties across wide ranges of temperature and pressure. For fibrous insulation, conventional measurement techniques in laboratory settings are typically limited to temperatures much lower than what is reached in atmosphere entry scenarios. Moreover, it is often the case that only temperature measurements are available, meaning that the thermal conductivity of the insulation must be indirectly inferred as an inverse problem. We propose a Bayesian framework using information field theory (IFT) to reconstruct the thermal conductivity of high-temperature fibrous insulation from sparse experimental data. Under IFT, the conductivity is represented as a Gaussian process, and the physics is enforced via a physics-informed prior over the temperature derived from the heat equation. Bayes's rule produces an infinite-dimensional posterior distribution that quantifies uncertainty about the conductivity which can be evaluated in extrapolation regimes. We apply the method to Opacified Fibrous Insulation with both synthetic and experimental data to reconstruct the thermal conductivity beyond the experimental regime. The inferred conductivities are validated against reference data and then propagated into high-fidelity digital twins of flexible TPS performance under Mars and Earth entry trajectories. The results show that IFT yields accurate predictions with quantified uncertainty, enabling robust TPS sizing in regimes inaccessible to direct measurement. △ Less

Submitted 21 January, 2026; originally announced January 2026.

Economic complexity and regional development in India: Insights from a state-industry bipartite network

Authors: Joel M Thomas, Abhijit Chakraborty

Abstract: This study investigates the economic complexity of Indian states by constructing a state-industry bipartite network using firm-level data on registered companies and their paid-up capital. We compute the Economic Complexity Index and apply the fitness-complexity algorithm to quantify the diversity and sophistication of productive capabilities across the Indian states and two union territories. The… ▽ More This study investigates the economic complexity of Indian states by constructing a state-industry bipartite network using firm-level data on registered companies and their paid-up capital. We compute the Economic Complexity Index and apply the fitness-complexity algorithm to quantify the diversity and sophistication of productive capabilities across the Indian states and two union territories. The results reveal substantial heterogeneity in regional capability structures, with states such as Maharashtra, Karnataka, and Delhi exhibiting consistently high complexity, while others remain concentrated in ubiquitous, low-value industries. The analysis also shows a strong positive relationship between complexity metrics and per-capita Gross State Domestic Product, underscoring the role of capability accumulation in shaping economic performance. Additionally, the number of active firms in India demonstrates a persistent exponential growth at an annual rate of 11.2%, reflecting ongoing formalization and industrial expansion. The ordered binary matrix displays the characteristic triangular structure observed in complexity studies, validating the applicability of complexity frameworks at the sub-national level. This work highlights the usefulness of firm-based data for assessing regional productive structures and emphasizes the importance of capability-oriented strategies for fostering balanced and sustainable development across Indian states. By demonstrating the usefulness of firm registry data in data constrained environments, this study advances the empirical application of economic complexity methods and provides a quantitative foundation for capability-oriented industrial and regional policy in India. △ Less

Submitted 18 January, 2026; originally announced January 2026.

Comments: 18 pages, 6 figures

Report number: RIKEN-iTHEMS-Report-26

Microwave-acoustic-based isolated gate driver for power electronics

Authors: Liyang Jin, Zichen Xi, Joseph G. Thomas, Jun Ji, Yuanzhi Zhang, Nuo Chen, Yizheng Zhu, Linbo Shao, Liyan Zhu

Abstract: Electrical isolation is critical to ensure safety and minimize electromagnetic interference (EMI), yet existing methods struggle to simultaneously transmit power and signals through a unified channel. Here we demonstrate a mechanically-isolated gate driver based on microwave-frequency surface acoustic wave (SAW) device on lithium niobate that achieves galvanic isolation of 2.75 kV with ultralow is… ▽ More Electrical isolation is critical to ensure safety and minimize electromagnetic interference (EMI), yet existing methods struggle to simultaneously transmit power and signals through a unified channel. Here we demonstrate a mechanically-isolated gate driver based on microwave-frequency surface acoustic wave (SAW) device on lithium niobate that achieves galvanic isolation of 2.75 kV with ultralow isolation capacitance (0.032 pF) over 1.25 mm mechanical propagation length, delivering 13.4 V open-circuit voltage and 44.4 mA short-circuit current. We demonstrate isolated gate driving for a gallium nitride (GaN) high-electron-mobility transistor, achieving a turn-on time of 108.8 ns comparable to commercial drivers and validate its operation in a buck converter. In addition, our SAW device operates over an ultrawide temperature range from 0.5 K (-272.6 °C) to 544 K (271 °C). The microwave-frequency SAW devices offer inherent EMI immunity and potential for heterogeneous integration on multiple semiconductor platforms, enabling compact, high-performance isolated power and signal transmission in advanced power electronics. △ Less

Submitted 13 April, 2026; v1 submitted 17 November, 2025; originally announced November 2025.

Tensor gravity gradiometry with a single-axis atom gradiometer

Authors: Ryan J. Thomas, Samuel Legge, John D. Close

Abstract: We propose a method for using a single-axis atom interferometric gravity gradiometer to measure off-diagonal elements of the gravity gradient tensor. By tilting the gradiometer, the measured gradient becomes a linear combination of different components of the gravity gradient tensor, and through multiple measurements at different tilts the separate tensor components can be inferred. We present a t… ▽ More We propose a method for using a single-axis atom interferometric gravity gradiometer to measure off-diagonal elements of the gravity gradient tensor. By tilting the gradiometer, the measured gradient becomes a linear combination of different components of the gravity gradient tensor, and through multiple measurements at different tilts the separate tensor components can be inferred. We present a theoretical and numerical investigation of this technique, both for terrestrial surveys where the tilt is statically set by the user and for surveys where a strapdown sensor is dynamically tilted by the motion of the platform. We show that the gradiometer's sensitivity to the vertical gravity gradient is only slightly reduced by this method while allowing for more gradiometer information to be obtained. Major sources of error and loss of sensitivity on dynamic platforms are shown to be mitigated using an optical-gimbal technique employing commercially-available fibre-optic gyroscopes and tip-tilt mirrors. △ Less

Submitted 13 November, 2025; v1 submitted 25 October, 2025; originally announced October 2025.

Comments: 10 pages, 4 figures

Journal ref: Physical Review A 112, 053314 (2025)

Vortex Propagation in Orbital Angular Momentum Beams and the Effects of a Limited Aperture

Authors: Ryan Husband, Jessica Eastman, Ryan J. Thomas, Simon A. Haine, Rhys H. Eagle, John D. Close, Samuel Legge

Abstract: When generating light with orbital angular momentum by imprinting orbital phase onto a standard Gaussian beam, it is often assumed that the propagation of the generated spatial mode is a Laguerre-Gaussian. However, the true propagation of this beam in a realistic, aperture-limited optical system is non-trivial and has not been thoroughly explored in existing literature. We explore a numerical mode… ▽ More When generating light with orbital angular momentum by imprinting orbital phase onto a standard Gaussian beam, it is often assumed that the propagation of the generated spatial mode is a Laguerre-Gaussian. However, the true propagation of this beam in a realistic, aperture-limited optical system is non-trivial and has not been thoroughly explored in existing literature. We explore a numerical model that shows the development of an optical vortex mode, propagating from the plane of phase modulation, and the relation of these dynamics to the orbital phase factor $\ell$ and the spatial bandwidth of the optical system. The results of this model are compared to experimental data for beams with $\ell$ values 1, 2, 5, and 10 propagating through a range of spatial filters, with the described model showing agreement in the near field regime. △ Less

Submitted 23 October, 2025; originally announced October 2025.

Comments: 17 pages, 7 figures

On the enhanced Balmer emission of hydrogen in helium Capacitively Coupled Radio Frequency (CCRF) plasma

Authors: Varsha S, Prabhakar Srivastav, Yukti Goel, Milaan Patel, Hem Chandra Joshi, Jinto Thomas

Abstract: The present study investigates the observation and enhancement in the intensity of the hydrogen Balmer series emission in a He CCRF plasma using optical emission spectroscopy (OES). In addition to the characteristic line emission of He atoms, the Balmer series of hydrogen and the molecular emission of N2 are also observed in the He discharge. These emissions were primarily attributed to the presen… ▽ More The present study investigates the observation and enhancement in the intensity of the hydrogen Balmer series emission in a He CCRF plasma using optical emission spectroscopy (OES). In addition to the characteristic line emission of He atoms, the Balmer series of hydrogen and the molecular emission of N2 are also observed in the He discharge. These emissions were primarily attributed to the presence of water vapor in the chamber. In order to confirm the role of He, the study is also performed using air and Ar where no such Balmer series emissions is seen. Experimental evidence suggests that He metastables transfer energy to trace amount of water content present in the vacuum chamber. The results point towards the hypothesis that energy exchange between metastable He and water molecules could be the underlying mechanism. Since the energy of He metastables exceeds the ionization energy of H or H2O molecule, Penning ionization is expected to occur upon their interaction. The H ions formed as a result, consequently recombine with electrons in the plasma, emitting the Balmer series. Furthermore, the emission intensity of the Balmer series of H depends on the electron density of the He plasma. Experiments also show significant deviations in the intensity ratios of the Balmer series from conventional discharges, indicating difference in the underlying population mechanism. A Collisional Radiative (CR) model for measured plasma parameters was used to estimate the metastable population density to understand the mechanism behind the enhancement of the emission intensity. The increase in the metastable densities as well as the radiative recombination cross section appear to be responsible for the observed enhancement. We believe these results will be significant in terms of applications, in addition to providing a fundamental understanding of energy transfer between metastables of He and H2O. △ Less

Submitted 19 September, 2025; originally announced September 2025.

Fabrication of thin planar radiopure foils with 82Se for the SuperNEMO Demonstrator

Authors: X. Aguerre, A. Barabash, A. Basharina-Freshville, M. Bongrand, Ch. Bourgeois, D. Breton, R. Breier, J. Busto, C. Cerna, J. Cesar, M. Ceschia, E. Chauveau, S. De Capua, D. Duchesneau, J. J. Evans, D. V. Filosofov, M. Granjon, M. Hoballah, R. Hodák, J. Horkley, A. Jeremie, S. Jullian, J. Kaizer, A. A. Klimenko, O. Kochetov , et al. (50 additional authors not shown)

Abstract: The SuperNEMO Demonstrator, designed to search for double beta decay using enriched 82Se, has been assembled in the Modane Underground Laboratory under the French Alps. Thin foils with radio - purified and enriched 82Se are installed centrally in the detector. A novel foil fabrication method has been developed, improving the radiopurity achieved in the previous generation experiment. It consists o… ▽ More The SuperNEMO Demonstrator, designed to search for double beta decay using enriched 82Se, has been assembled in the Modane Underground Laboratory under the French Alps. Thin foils with radio - purified and enriched 82Se are installed centrally in the detector. A novel foil fabrication method has been developed, improving the radiopurity achieved in the previous generation experiment. It consists of wrapping standalone selenium pads in raw Mylar, combined with selenium purified by a new reverse-chromatography method. This paper describes the features of these foils, their fabrication process, the characterization results, and the integration of the foils into the SuperNEMO Demonstrator. △ Less

Submitted 10 September, 2025; originally announced September 2025.

Comments: 20 pages, 11 figures, 7 tables

Performance of the MORA Apparatus for Testing Time-Reversal Invariance in Nuclear Beta Decay

Authors: N. Goyal, A. Singh, S. Daumas-Tschopp, L. M. Motilla Martinez, G. Ban, V. Bosquet, J. F. Cam, P. Chauveau, S. Chinthakayala, G. Fremont, R. P. De Groote, F. de Oliveira Santos, T. Eronen, A. Falkowski, X. Flechard, Z. Ge, M. Gonzalez-Alonso, H. Guerin, L. Hayen, A. Jaries, M. Jbayli, A. Jokinen, A. Kankainen, B. Kootte, R. Kronholm , et al. (18 additional authors not shown)

Abstract: The MORA experimental setup is designed to measure the triple-correlation D parameter in nuclear beta decay. The D coefficient is sensitive to possible violations of time-reversal invariance. The experimental configuration consists of a transparent Paul trap surrounded by a detection setup with alternating beta and recoil-ion detectors. The octagonal symmetry of the detection setup optimizes the s… ▽ More The MORA experimental setup is designed to measure the triple-correlation D parameter in nuclear beta decay. The D coefficient is sensitive to possible violations of time-reversal invariance. The experimental configuration consists of a transparent Paul trap surrounded by a detection setup with alternating beta and recoil-ion detectors. The octagonal symmetry of the detection setup optimizes the sensitivity of positron-recoil-ion coincidence rates to the D correlation, while reducing systematic effects. MORA utilizes an innovative in-trap laser polarization technique. The design and performance of the ion trap, associated beamline elements, lasers and beta and recoil-ion detectors, are presented. Recent progress towards the polarization proof-of-principle is described. △ Less

Submitted 22 April, 2025; originally announced April 2025.

Comments: 18 pages

Plasma lens for focusing attosecond pulses

Authors: E. Svirplys, H. Jones, G. Loisch, J Thomas, M Huck, O. Kornilov, J. M. Garland, J. C. Wood, M. J. J. Vrakking, J. Osterhoff, B. Schütte

Abstract: Attosecond pulses provide unique opportunities for studies of time-resolved electron dynamics. However, focusing these pulses, typically ranging from the vacuum ultraviolet to the soft-X-ray region, remains challenging. Conventional refractive lenses are not suitable owing to the large dispersion and the strong absorption, while reflective optics, despite avoiding these issues, still lead to high… ▽ More Attosecond pulses provide unique opportunities for studies of time-resolved electron dynamics. However, focusing these pulses, typically ranging from the vacuum ultraviolet to the soft-X-ray region, remains challenging. Conventional refractive lenses are not suitable owing to the large dispersion and the strong absorption, while reflective optics, despite avoiding these issues, still lead to high losses. Here we propose a tunable plasma lens capable of focusing attosecond pulses, and experimentally demonstrate focusing of these pulses at extreme-ultraviolet photon energies around 20 eV and 80 eV. A key advantage is its compatibility with nonlinear frequency conversion processes like high-harmonic generation. The different focusing properties of the fundamental light and the generated harmonic frequencies allow for efficient separation of these components. Consequently, the transmission of high-harmonic generation beamlines can be increased to more than 80%, making this approach highly suitable for photon-demanding applications. △ Less

Submitted 15 December, 2025; v1 submitted 15 April, 2025; originally announced April 2025.

Comments: 31 pages, 15 figures. Nat. Photon. (2025)

Measurement of Trace Elements in Volcanic Materials: Consequences for the Cretaceous-Tertiary Mass Extinction, Geoneutrinos and the Origin of the Hawaii's Archipelago

Authors: Pedro V. Guillaumon, Iuda D. Goldman, Eric B. Norman, Keenan J. Thomas, Paulo R. Pascholati, Ross E. Meyer, Jordan L. Sabella, Alan R. Smith

Abstract: Seventeen representative samples of volcanic origin were collected from Ecuador (Pichincha Volcano), Iceland (Eyjafjallajökull Volcano), India (Deccan Traps), Hawaii, Kilimanjaro, Mt. Etna, Rwanda (Virunga Mountains), and Uganda (Virunga Mountains). Neutron activation analysis (NAA) was performed to determine the concentration of 33 chemical elements, including 21 trace elements, 20 heavy metals,… ▽ More Seventeen representative samples of volcanic origin were collected from Ecuador (Pichincha Volcano), Iceland (Eyjafjallajökull Volcano), India (Deccan Traps), Hawaii, Kilimanjaro, Mt. Etna, Rwanda (Virunga Mountains), and Uganda (Virunga Mountains). Neutron activation analysis (NAA) was performed to determine the concentration of 33 chemical elements, including 21 trace elements, 20 heavy metals, and 9 rare earth elements: Al, As, Ba, Ca, Ce, Cl, Co, Cr, Cs, Dy, Eu, Fe, Hf, K, La, Lu, Mg, Mn, Na, Nd, Rb, Sb, Sc, Sm, Sr, Ta, Tb, Th, Ti, U, Yb, Zn, and Zr. Correlation analysis of the abundance of samples from different islands in the Hawaii archipelago (Kauai, Kilauea, Mauna Loa, and Haleakala) confirmed that the islands were likely formed by two different lava sources. Additionally, the upper limit of iridium was determined in 11 of these samples using Bayesian analysis, which does not support the hypothesis that volcanic activity caused the extinction of the dinosaurs. We also discuss how the abundance of thorium and uranium in lava from different geological formations and depths can contribute to building a better map of natural radioisotope occurrences on Earth, which is important for geoneutrino experiments. A high abundance of rare elements was reported in some of the analyzed locations, indicating potential commercial interest and the possibility of exploring volcanoes as sources of chemical elements used in electronic devices. △ Less

Submitted 11 March, 2025; originally announced March 2025.

Room-temperature mid-infrared detection using metasurface-absorber-integrated phononic crystal oscillator

Authors: Zichen Xi, Zengyu Cen, Dongyao Wang, Joseph G. Thomas, Bernadeta R. Srijanto, Ivan I. Kravchenko, Jiawei Zuo, Honghu Liu, Jun Ji, Yizheng Zhu, Yu Yao, Linbo Shao

Abstract: Mid-infrared (MIR) detectors find extensive applications in chemical sensing, spectroscopy, communications, biomedical diagnosis and space explorations. Alternative to semiconductor MIR photodiodes and bolometers, mechanical-resonator-based MIR detectors show advantages in higher sensitivity and lower noise at room temperature, especially towards longer wavelength infrared. Here, we demonstrate un… ▽ More Mid-infrared (MIR) detectors find extensive applications in chemical sensing, spectroscopy, communications, biomedical diagnosis and space explorations. Alternative to semiconductor MIR photodiodes and bolometers, mechanical-resonator-based MIR detectors show advantages in higher sensitivity and lower noise at room temperature, especially towards longer wavelength infrared. Here, we demonstrate uncooled room-temperature MIR detectors based on lithium niobate surface acoustic wave phononic crystal (PnC) resonators integrated with wavelength-and-polarization-selective metasurface absorber arrays. The detection is based on the resonant frequency shift induced by the local temperature change due to MIR absorptions. The PnC resonator is configured in an oscillating mode, enabling active readout and low frequency noise. Compared with detectors based on tethered thin-film mechanical resonators, our non-suspended, fully supported PnC resonators offer lower noise, faster thermal response, and robustness in both fabrication and practical applications. Our 1-GHz oscillator-based MIR detector shows a relative frequency deviation of $5.24 \times 10^{-10}$ Hz$^{-1/2}$ at an integration time of 50 $μ$s, leading to an incident noise equivalent power of 197 pW/$\sqrt{\mathrm{Hz}}$ when input 6-$μ$m MIR light is modulated at 1.8 kHz, and a large dynamic range of 107 in incident MIR power. Our device architecture is compatible with the scalable manufacturing process and can be readily extended to a broader spectral range by tailoring the absorbing wavelengths of metasurface absorbers. △ Less

Submitted 9 July, 2025; v1 submitted 15 March, 2025; originally announced March 2025.

Journal ref: Laser Photonics Rev 2025, e00498

A Comparison of Calcium Sources for Ion-Trap Loading via Laser Ablation

Authors: Daisy R H Smith, Silpa Muralidharan, Roland Hablutzel, Georgina Croft, Klara Theophilo, Alexander Owens, Yashna N D Lekhai, Scott J Thomas, Cameron Deans

Abstract: Trapped-ion technology is a leading approach for scalable quantum computing. A key element of ion trapping is reliable loading of atomic sources into the trap. While thermal atomic ovens have traditionally been used for this purpose, laser ablation has emerged as a viable alternative in recent years, offering the advantages of faster and more localized loading with lower heat dissipation. Calcium… ▽ More Trapped-ion technology is a leading approach for scalable quantum computing. A key element of ion trapping is reliable loading of atomic sources into the trap. While thermal atomic ovens have traditionally been used for this purpose, laser ablation has emerged as a viable alternative in recent years, offering the advantages of faster and more localized loading with lower heat dissipation. Calcium is a well-established ion for qubit applications. Here we examine a range of calcium sources for ablation and provide a comprehensive analysis of each. We consider factors such as ease of use, temperature and yield of the ablation plume, and the lifetime of ablation spots. For each target, we estimate the number of trappable atoms per ablation pulse for a typical surface and 3D ion trap. △ Less

Submitted 13 March, 2025; originally announced March 2025.

Comments: 10 pages, 7 figures

Journal ref: Applied Physics B, 131.8,164 (2025)

Calibration of a $Δ$E-E telescope based on CeBr$_3$ scintillator for secondary charged particles measurements in hadron therapy

Authors: L. Gesson, J. Gross, C. Mozzi, C. Reibel, Ch. Finck, S. Higueret, T. D. Le, E. Traykov, J. C. Thomas, N. Arbor, M. Pullia, G. Harmant, M. Vanstalle

Abstract: Hadrontherapy is an established cancer treatment method that enables a more localized dose deposition compared to conventional radiotherapy, potentially reducing the dose to surrounding healthy tissues in certain clinical cases. However, a key limitation in current treatment planning lies in the limited experimental data available for the characterization of secondary particles generated by nuclea… ▽ More Hadrontherapy is an established cancer treatment method that enables a more localized dose deposition compared to conventional radiotherapy, potentially reducing the dose to surrounding healthy tissues in certain clinical cases. However, a key limitation in current treatment planning lies in the limited experimental data available for the characterization of secondary particles generated by nuclear interactions of the primary beam with tissues, which directly impacts the accuracy of Monte Carlo tools and analytical models used in dose calculations. Indeed, this leads to the adoption of larger safety margins and can limit the use of hadrontherapy for treating certain complex or sensitive tumor locations. This work is part of the context of the characterization of secondary charged particles generated by ion beams in the energy range relevant for particle therapy applications, using a $ΔE-E$ telescope comprising a CeBr$_3$ crystal scintillator and a plastic scintillator. The calibration and response of this telescope to ions commonly used in clinical settings is presented in this work, highlighting adherence to Birks' law for accurate energy measurements. This study is the first to optimize a $ΔE-E$ telescope combining CeBr$_3$ and plastic scintillators specifically for secondary particle detection in hadrontherapy. It represents an essential step toward the experimental acquisition of nuclear data, enabling accurate measurement and identification of secondary charged particles generated by therapeutic beams in tissue-equivalent materials. The system is designed for use in controlled experimental setups that reproduce clinical conditions, with the goal of improving the predictive accuracy of treatment planning software through enhanced Monte Carlo simulation inputs. △ Less

Submitted 3 July, 2025; v1 submitted 7 February, 2025; originally announced February 2025.

The Impact of Helium Exposure on the PMTs of the SuperNEMO Experiment

Authors: SuperNEMO Collaboration, X. Aguerre, A. S. Barabash, A. Basharina-Freshville, M. Bongrand, Ch. Bourgeois, D. Breton, R. Breier, J. Busto, C. Cerna, M. Ceschia, E. Chauveau, A. Chopra, L. Dawson, D. Duchesneau, J. J. Evans, D. Filosofov, X. Garrido, C. Girard-Carillo, M. Granjon, M. Hoballah, R. Hodák, G. Horner, M. H. Hussain, A. Islam , et al. (54 additional authors not shown)

Abstract: The performance of Hamamatsu 8" photomultiplier tubes (PMTs) of the type used in the SuperNEMO neutrinoless double-beta decay experiment (R5912-MOD), is investigated as a function of exposure to helium (He) gas. Two PMTs were monitored for over a year, one exposed to varying concentrations of He, and the other kept in standard atmospheric conditions as a control. Both PMTs were exposed to light si… ▽ More The performance of Hamamatsu 8" photomultiplier tubes (PMTs) of the type used in the SuperNEMO neutrinoless double-beta decay experiment (R5912-MOD), is investigated as a function of exposure to helium (He) gas. Two PMTs were monitored for over a year, one exposed to varying concentrations of He, and the other kept in standard atmospheric conditions as a control. Both PMTs were exposed to light signals generated by a Bi-207 radioactive source that provided consistent large input PMT signals similar to those that are typical of the SuperNEMO experiment. The energy resolution of PMT signals corresponding to 1 MeV energy scale determined from the Bi-207 decay spectrum, shows a negligible degradation with He exposure; however the rate of after-pulsing shows a clear increase with He exposure, which is modelled and compared to diffusion theory. A method for reconstructing the partial pressure of He within the PMT and a method for determining the He breakdown point, are introduced. The implications for long-term SuperNEMO operations are briefly discussed. △ Less

Submitted 5 March, 2025; v1 submitted 23 January, 2025; originally announced January 2025.

Calorimeter commissioning of the SuperNEMO Demonstrator

Authors: X. Aguerre, A. Barabash, A. Basharina-Freshville, M. Bongrand, Ch. Bourgeois, D. Boursette, D. Breton, R. Breier, J. Busto, S. Calvez, C. Cerna, M. Ceschia, E. Chauveau, L. Dawson, D. Duchesneau, J. J. Evans, D. V. Filosofov, X. Garrido, C. Girard-Carillo, M. Granjon, B. Guillon, M. Hoballah, R. Hodák, J. Horkley, A. Huber , et al. (56 additional authors not shown)

Abstract: The SuperNEMO experiment is searching for neutrinoless double beta decay of \textsuperscript{82}Se, with the unique combination of a tracking detector and a segmented calorimeter. This feature allows to detect the two electrons emitted in the decay and measure their individual energy and angular distribution. The SuperNEMO calorimeter consists of 712 plastic scintillator blocks readout by large PM… ▽ More The SuperNEMO experiment is searching for neutrinoless double beta decay of \textsuperscript{82}Se, with the unique combination of a tracking detector and a segmented calorimeter. This feature allows to detect the two electrons emitted in the decay and measure their individual energy and angular distribution. The SuperNEMO calorimeter consists of 712 plastic scintillator blocks readout by large PMTs. After the construction of the demonstrator calorimeter underground, we have performed its first commissioning using $γ$-particles from calibration sources or from the ambient radioactive background. This article presents the quality assurance tests of the SuperNEMO demonstrator calorimeter and its first time and energy calibrations, with the associated methods. △ Less

Submitted 17 March, 2025; v1 submitted 23 December, 2024; originally announced December 2024.

Electron Phase Detection in Single Molecules by Interferometry

Authors: Zhixin Chen, Jie-Ren Deng, Mengyun Wang, Nikolaos Farmakidis, Jonathan Baugh, Harish Bhaskaran, Jan A. Mol, Harry L. Anderson, Lapo Bogani, James O. Thomas

Abstract: Interferometry has underpinned a century of discoveries, ranging from the disproval of the ether theory to the detection of gravitational waves, offering insights into wave dynamics with unrivalled precision through the measurement of phase relationships. In electronics, phase-sensitive measurements can probe the nature of transmissive topological and quantum states, but are only possible using co… ▽ More Interferometry has underpinned a century of discoveries, ranging from the disproval of the ether theory to the detection of gravitational waves, offering insights into wave dynamics with unrivalled precision through the measurement of phase relationships. In electronics, phase-sensitive measurements can probe the nature of transmissive topological and quantum states, but are only possible using complex device structures in magnetic fields. Here we demonstrate electronic interferometry in a single-molecule device through the study of non-equilibrium Fano resonances. We show the phase difference between an electronic orbital and a coupled Fabry-Perot resonance are tuneable through electric fields, and consequently it is possible to read out quantum information in the smallest devices, offering new avenues for the coherent manipulation down to single molecules. △ Less

Submitted 17 November, 2024; originally announced November 2024.

Effect of ambient on the dynamics of re-deposition in the rear laser ablation of a thin film

Authors: Renjith Kumar R, B R Geethika, Nancy Verma, Vishnu Chaudhari, Janvi Dave, Hem Chandra Joshi, Jinto Thomas

Abstract: In this work, we report an innovative pump-probe based experimental set up, to study the melting, subsequent evaporation, plasma formation and redeposition in a thin film coated on a glass substrate under different ambient conditions and laser fluences. The ambient conditions restrict the expansion of the plasma plume. At high ambient pressure, plume expansion stops closer to the substrate and get… ▽ More In this work, we report an innovative pump-probe based experimental set up, to study the melting, subsequent evaporation, plasma formation and redeposition in a thin film coated on a glass substrate under different ambient conditions and laser fluences. The ambient conditions restrict the expansion of the plasma plume. At high ambient pressure, plume expansion stops closer to the substrate and get re-deposited at the site of the ablation. This helps in the identification of multiple processes and their temporal evolutions during the melting, expansion and re-deposition stages. The ambient conditions affect the plasma plume formed upon ablation, thus modulating the transmission of probe laser pulses, which provides information about the plume dynamics. Further, the study offers valuable insights into the laser-based ablation of thin film coatings, which will have implications in in situ cleaning of view ports on large experimental facilities such as tokamaks and other systems e.g. coating units, pulsed laser deposition, Laser induced forward transfer, Laser surface structuring, etc. △ Less

Submitted 10 October, 2024; originally announced October 2024.

Effect of polarization on spectroscopic characterization of laser produced aluminium plasma

Authors: B. R. Geethika, Jinto Thomas, Renjith Kumar R, Janvi Dave, Hem Chandra Joshi

Abstract: Laser-induced breakdown spectroscopy (LIBS) is a well-established technique widely used in fundamental research and diverse practical fields. Polarization-resolved LIBS, a variant of this technique, aims to improve the sensitivity, which is a critical aspect in numerous scientific domains. In our recent work we demonstrated that the degree of polarization (DOP) in the emission depends on the spati… ▽ More Laser-induced breakdown spectroscopy (LIBS) is a well-established technique widely used in fundamental research and diverse practical fields. Polarization-resolved LIBS, a variant of this technique, aims to improve the sensitivity, which is a critical aspect in numerous scientific domains. In our recent work we demonstrated that the degree of polarization (DOP) in the emission depends on the spatial location and time in a nano second laser generated aluminium plasma1. Present study investigates the effect of polarized emission on the estimation of plasma parameters. The plasma parameters are estimated using the conventional spectroscopic methods such as Boltzmann plot and line intensity ratio for the estimation of electron temperature and Stark broadening for estimating the electron density. The estimated plasma temperature using Boltzmann plot method shows large errors in electron temperature for the locations where DOP is higher. However, the electron density estimated using the Stark width does not show such variation. The observed ambiguity in temperature estimation using the Boltzmann plot method appears to be a consequence of deviation from expected Maxwell Boltzmann distribution of population of the involved energy levels. These findings highlight the need of assessing the DOP of the plasma before selecting the polarization for PRLIBS or temperature estimation using Boltzmann plots in elemental analysis. △ Less

Submitted 9 October, 2024; originally announced October 2024.

Low-phase-noise surface-acoustic-wave oscillator using an edge mode of a phononic band gap

Authors: Zichen Xi, Joseph G. Thomas, Jun Ji, Dongyao Wang, Zengyu Cen, Ivan I. Kravchenko, Bernadeta R. Srijanto, Yu Yao, Yizheng Zhu, Linbo Shao

Abstract: Low-phase-noise microwave-frequency integrated oscillators provide compact solutions for various applications in signal processing, communications, and sensing. Surface acoustic waves (SAW), featuring orders-of-magnitude shorter wavelength than electromagnetic waves at the same frequency, enable integrated microwave-frequency systems with much smaller footprint on chip. SAW devices also allow high… ▽ More Low-phase-noise microwave-frequency integrated oscillators provide compact solutions for various applications in signal processing, communications, and sensing. Surface acoustic waves (SAW), featuring orders-of-magnitude shorter wavelength than electromagnetic waves at the same frequency, enable integrated microwave-frequency systems with much smaller footprint on chip. SAW devices also allow higher quality (Q) factors than electronic components at room temperature. Here, we demonstrate a low-phase-noise gigahertz-frequency SAW oscillator on 128°Y-cut lithium niobate, where the SAW resonator occupies a footprint of 0.05 mm$^2$. Leveraging phononic crystal bandgap-edge modes to balance between Q factors and insertion losses, our 1-GHz SAW oscillator features a low phase noise of -132.5 dBc/Hz at a 10 kHz offset frequency and an overlapping Hadamard deviation of $6.5\times10^{-10}$ at an analysis time of 64 ms. The SAW resonator-based oscillator holds high potential in developing low-noise sensors and acousto-optic integrated circuits. △ Less

Submitted 20 February, 2025; v1 submitted 4 September, 2024; originally announced September 2024.

Journal ref: Phys. Rev. Applied 23, 024054 (2025)

Digital stabilization of an IQ modulator in the carrier suppressed single side-band (CS-SSB) mode for atom interferometry

Authors: Arif Ullah, Samuel Legge, John D. Close, Simon A. Haine, Ryan J. Thomas

Abstract: We present an all-digital method for stabilising the phase biases in an electro-optic I/Q modulator for carrier-suppressed single-sideband modulation. Building on the method presented in S. Wald \ea, Appl. Opt. \textbf{62}, 1-7 (2023), we use the Red Pitaya STEMlab 125-14 platform to digitally generate and demodulate an auxiliary radio-frequency tone whose beat with the optical carrier probes the… ▽ More We present an all-digital method for stabilising the phase biases in an electro-optic I/Q modulator for carrier-suppressed single-sideband modulation. Building on the method presented in S. Wald \ea, Appl. Opt. \textbf{62}, 1-7 (2023), we use the Red Pitaya STEMlab 125-14 platform to digitally generate and demodulate an auxiliary radio-frequency tone whose beat with the optical carrier probes the I/Q modulator's phase imbalances. We implement a multiple-input, multiple-output integral feedback controller which accounts for unavoidable cross-couplings in the phase biases to lock the error signals at exactly zero where optical power fluctuations have no impact on phase stability. We demonstrate $>23\,\rm dB$ suppression of the optical carrier relative to the desired sideband at $+3.4\,\rm GHz$ over a period of $15$ hours and over temperature variations of $20^\circ\rm C$. △ Less

Submitted 28 October, 2024; v1 submitted 29 August, 2024; originally announced August 2024.

Comments: 7 pages, 7 figures. Two column format, some corrections and updates from previous version

Journal ref: Applied Optics 63, 31 (2024)

Scalable DAQ system operating the CHIPS-5 neutrino detector

Authors: Belén Alonso Rancurel, Son Cao, Thomas J. Carroll, Rhys Castellan, Erika Catano-Mur, John P. Cesar, João A. B. Coelho, Patrick Dills, Thomas Dodwell, Jack Edmondson, Daan van Eijk, Quinn Fetterly, Zoé Garbal, Stefano Germani, Thomas Gilpin, Anthony Giraudo, Alec Habig, Daniel Hanuska, Harry Hausner, Wilson Y. Hernandez, Anna Holin, Junting Huang, Sebastian B. Jones, Albrecht Karle, George Kileff , et al. (35 additional authors not shown)

Abstract: The CHIPS R&D project focuses on development of low-cost water Cherenkov neutrino detectors through novel design strategies and resourceful engineering. This work presents an end-to-end DAQ solution intended for a recent 5 kt CHIPS prototype, which is largely based on affordable mass-produced components. Much like the detector itself, the presented instrumentation is composed of modular arrays tha… ▽ More The CHIPS R&D project focuses on development of low-cost water Cherenkov neutrino detectors through novel design strategies and resourceful engineering. This work presents an end-to-end DAQ solution intended for a recent 5 kt CHIPS prototype, which is largely based on affordable mass-produced components. Much like the detector itself, the presented instrumentation is composed of modular arrays that can be scaled up and easily serviced. A single such array can carry up to 30 photomultiplier tubes (PMTs) accompanied by electronics that generate high voltage in-situ and deliver time resolution of up to 0.69 ns. In addition, the technology is compatible with the White Rabbit timing system, which can synchronize its elements to within 100 ps. While deployment issues did not permit the presented DAQ system to operate beyond initial evaluation, the presented hardware and software successfully passed numerous commissioning tests that demonstrated their viability for use in a large-scale neutrino detector, instrumented with thousands of PMTs. △ Less

Submitted 20 August, 2024; originally announced August 2024.

Comments: 30 pages, 28 figures, submitted to MDPI Applied Sciences, Special Issue: Advanced Neutrino Detector Development and Application

Optimal strategies for low-noise detection of atoms using resonant frequency modulation spectroscopy in cold atom interferometers

Authors: Ryan J. Thomas, Samuel R. Legge, Simon A. Haine, John D. Close

Abstract: Resonant frequency modulation spectroscopy has been previously used as a highly-sensitive method for measuring the output of cold atom interferometers. Using a detailed model that accounts for optical saturation, laser intensities and atomic densities that vary spatially, and radiation pressure on the atoms, we theoretically investigate under what parameter regimes the optimum signal-to-noise rati… ▽ More Resonant frequency modulation spectroscopy has been previously used as a highly-sensitive method for measuring the output of cold atom interferometers. Using a detailed model that accounts for optical saturation, laser intensities and atomic densities that vary spatially, and radiation pressure on the atoms, we theoretically investigate under what parameter regimes the optimum signal-to-noise ratio is found under experimentally realistic conditions. We compare this technique to the standard method of fluorescence imaging and find that it outperforms fluorescence imaging for compact interferometers using condensed atomic sources or where the photon collection efficiency is limited. However, we find that fluorescence imaging is likely to be the preferred method when using squeezed atomic sources due to limited atom number. △ Less

Submitted 10 December, 2024; v1 submitted 12 August, 2024; originally announced August 2024.

Comments: 9 pages, 5 figures

Journal ref: Physical Review A 110, 063706 (2024)

Self-consistent Coulomb interactions for machine learning interatomic potentials

Authors: Jack Thomas, William J. Baldwin, Gábor Csányi, Christoph Ortner

Abstract: A ubiquitous approach to obtain transferable machine learning-based models of potential energy surfaces for atomistic systems is to decompose the total energy into a sum of local atom-centred contributions. However, in many systems non-negligible long-range electrostatic effects must be taken into account as well. We introduce a general mathematical framework to study how such long-range effects c… ▽ More A ubiquitous approach to obtain transferable machine learning-based models of potential energy surfaces for atomistic systems is to decompose the total energy into a sum of local atom-centred contributions. However, in many systems non-negligible long-range electrostatic effects must be taken into account as well. We introduce a general mathematical framework to study how such long-range effects can be included in a way that (i) allows charge equilibration and (ii) retains the locality of the learnable atom-centred contributions to ensure transferability. Our results give partial explanations for the success of existing machine learned potentials that include equilibriation and provide perspectives how to design such schemes in a systematic way. To complement the rigorous theoretical results, we describe a practical scheme for fitting the energy and electron density of water clusters. △ Less

Submitted 16 June, 2024; originally announced June 2024.

Comments: 33 pages, 1 figure

MSC Class: 65E05; 74E15; 81V45; 81V70

Dual Open Atom Interferometry for Compact and Mobile Quantum Sensing

Authors: Yosri Ben-Aïcha, Zain Mehdi, Christian Freier, Stuart S. Szigeti, Paul B. Wigley, Lorcán O. Conlon, Ryan Husband, Samuel Legge, Rhys H. Eagle, Joseph J. Hope, Nicholas P. Robins, John D. Close, Kyle S. Hardman, Simon A. Haine, Ryan J. Thomas

Abstract: We demonstrate an atom interferometer measurement protocol compatible with operation on a dynamic platform. Our method employs two open interferometers, derived from the same atomic source, with different interrogation times to eliminate initial velocity dependence while retaining precision, accuracy, and long term stability. We validate the protocol by measuring gravitational tides, achieving a p… ▽ More We demonstrate an atom interferometer measurement protocol compatible with operation on a dynamic platform. Our method employs two open interferometers, derived from the same atomic source, with different interrogation times to eliminate initial velocity dependence while retaining precision, accuracy, and long term stability. We validate the protocol by measuring gravitational tides, achieving a precision of 4.5 μGal in 2000 runs (6.7 h), marking the first demonstration of inertial quantity measurement with open atom interferometry that achieves long-term phase stability. △ Less

Submitted 18 January, 2025; v1 submitted 1 May, 2024; originally announced May 2024.

Journal ref: Phys. Rev. Lett. 133, 263403 - Published 27 December, 2024

Terawatt-level three-stage pulse compression for all-attosecond pump-probe spectroscopy

Authors: E. Sobolev, M. Volkov, E. Svirplys, J. Thomas, T. Witting, M. J. J. Vrakking, B. Schütte

Abstract: The generation of terawatt (TW) near-single-cycle laser pulses is of high interest for applications including attosecond science. Here we demonstrate a three-stage post-compression scheme in a non-guided geometry using He as the nonlinear medium, resulting in the generation of multi-mJ pulses with a duration of 3.7 fs. Key features of this approach are its simplicity, robustness and high stability… ▽ More The generation of terawatt (TW) near-single-cycle laser pulses is of high interest for applications including attosecond science. Here we demonstrate a three-stage post-compression scheme in a non-guided geometry using He as the nonlinear medium, resulting in the generation of multi-mJ pulses with a duration of 3.7 fs. Key features of this approach are its simplicity, robustness and high stability, making it ideally suited for highly demanding applications such as attosecond-pump attosecond-probe spectroscopy (APAPS). This is demonstrated by performing two-color APAPS in Ar and Ne, where both simultaneous and sequential two-photon absorption are observed. Our approach is scalable to multi-TW powers. △ Less

Submitted 26 August, 2024; v1 submitted 28 April, 2024; originally announced April 2024.

Comments: 9 pages, 4 figures

The Design and Construction of the Chips Water Cherenkov Neutrino Detector

Authors: B. Alonso Rancurel, N. Angelides, G. Augustoni, S. Bash, B. Bergmann, N. Bertschinger, P. Bizouard, M. Campbell, S. Cao, T. J. Carroll, R. Castellan, E. Catano-Mur, J. P. Cesar, J. A. B. Coelho, P. Dills, T. Dodwell, J. Edmondson, D. van Eijk, Q. Fetterly, Z. Garbal, S. Germani, T. Gilpin, A. Giraudo, A. Habig, D. Hanuska , et al. (42 additional authors not shown)

Abstract: CHIPS (CHerenkov detectors In mine PitS) was a prototype large-scale water Cherenkov detector located in northern Minnesota. The main aim of the R&D project was to demonstrate that construction costs of neutrino oscillation detectors could be reduced by at least an order of magnitude compared to other equivalent experiments. This article presents design features of the CHIPS detector along with de… ▽ More CHIPS (CHerenkov detectors In mine PitS) was a prototype large-scale water Cherenkov detector located in northern Minnesota. The main aim of the R&D project was to demonstrate that construction costs of neutrino oscillation detectors could be reduced by at least an order of magnitude compared to other equivalent experiments. This article presents design features of the CHIPS detector along with details of the implementation and deployment of the prototype. While issues during and after the deployment of the detector prevented data taking, a number of key concepts and designs were successfully demonstrated. △ Less

Submitted 25 September, 2024; v1 submitted 22 January, 2024; originally announced January 2024.

CATLIFE (Complementary Arm for Target LIke FragmEnts): Spectrometer for Target like fragments at VAMOS++

Authors: Y. Son, Y. H. Kim, Y. Cho, S. Choi, S. Bae, K. I. Hahn, J. Park, A. Navin, A. Lemasson, M. Rejmund, D. Ramos, E. Clément, D. Ackermann, A. Utepov, C. Fougeres, J. C. Thomas, J. Goupil, G. Fremont, G. de France

Abstract: The multi-nucleon transfer reaction between 136Xe beam and 198Pt target at the beam energy 7 MeV/u was studied using the large acceptance spectrometer VAMOS++ coupled with the newly installed second arm time-of-flight and delayed $γ$-ray spectrometer CATLIFE (Complementary Arm for Target LIke FragmEnts). The CATLIFE detector is composed of a large area multi-wire proportional chamber and the EXOGA… ▽ More The multi-nucleon transfer reaction between 136Xe beam and 198Pt target at the beam energy 7 MeV/u was studied using the large acceptance spectrometer VAMOS++ coupled with the newly installed second arm time-of-flight and delayed $γ$-ray spectrometer CATLIFE (Complementary Arm for Target LIke FragmEnts). The CATLIFE detector is composed of a large area multi-wire proportional chamber and the EXOGAM HPGe clover detectors with an ion flight length of 1230 mm. Direct measurement of the target-like fragments (TLF) and the delayed $γ$-rays from the isomeric state helps to improve TLF identification. The use of the velocity of TLFs and the delayed $γ$-ray demonstrate the proof of principle and effectiveness of the new setup. △ Less

Submitted 13 November, 2023; originally announced November 2023.

Journal ref: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms Volume 540, July 2023, Pages 259-261

Particle Identification at VAMOS++ with Machine Learning Techniques

Authors: Y. Cho, Y. H. Kim, S. Choi, J. Park, S. Bae, K. I. Hahn, Y. Son, A. Navin, A. Lemasson, M. Rejmund, D. Ramos, D. Ackermann, A. Utepov, C. Fourgeres, J. C. Thomas, J. Goupil, G. Fremont, G. de France, Y. X. Watanabe, Y. Hirayama, S. Jeong, T. Niwase, H. Miyatake, P. Schury, M. Rosenbusch , et al. (23 additional authors not shown)

Abstract: Multi-nucleon transfer reaction between 136Xe beam and 198Pt target was performed using the VAMOS++ spectrometer at GANIL to study the structure of n-rich nuclei around N=126. Unambiguous charge state identification was obtained by combining two supervised machine learning methods, deep neural network (DNN) and positional correction using a gradient-boosting decision tree (GBDT). The new method re… ▽ More Multi-nucleon transfer reaction between 136Xe beam and 198Pt target was performed using the VAMOS++ spectrometer at GANIL to study the structure of n-rich nuclei around N=126. Unambiguous charge state identification was obtained by combining two supervised machine learning methods, deep neural network (DNN) and positional correction using a gradient-boosting decision tree (GBDT). The new method reduced the complexity of the kinetic energy calibration and outperformed the conventional method, improving the charge state resolution by 8% △ Less

Submitted 14 November, 2023; v1 submitted 13 November, 2023; originally announced November 2023.

Journal ref: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 541, August 2023, Pages 240-242

Femtosecond electron transfer dynamics across the D$_2$O/Cs$^+$/Cu(111) interface: The impact of hydrogen bonding

Authors: John Thomas, Jayita Patwari, Inga Langguth, Christopher Penschke, Ping Zhou, Karina Morgenstern, Uwe Bovensiepen

Abstract: Hydrogen bonding is essential in electron transfer processes at water-electrode interfaces. We study the impact of the H-bonding of water as a solvent molecule on real-time electron transfer dynamics across a Cs+-Cu(111) ion-metal interface using femtosecond time-resolved two-photon photoelectron spectroscopy. We distinguish in the formed water-alkali aggregates two regimes below and above two wat… ▽ More Hydrogen bonding is essential in electron transfer processes at water-electrode interfaces. We study the impact of the H-bonding of water as a solvent molecule on real-time electron transfer dynamics across a Cs+-Cu(111) ion-metal interface using femtosecond time-resolved two-photon photoelectron spectroscopy. We distinguish in the formed water-alkali aggregates two regimes below and above two water molecules per ion. Upon crossing the boundary of these regimes, the lifetime of the excess electron localized transiently at the Cs+ ion increases from 40 to 60 femtoseconds, which indicates a reduced alkali-metal interaction. Furthermore, the energy transferred to a dynamic structural rearrangement due to hydration is reduced from 0.3 to 0.2 eV concomitantly. These effects are a consequence of H-bonding and the beginning formation of a nanoscale water network. This finding is supported by real-space imaging of the solvatomers and vibrational frequency shifts of the OH stretch and bending modes calculated for these specific interfaces. △ Less

Submitted 30 September, 2023; originally announced October 2023.

Comments: 8 pages, 5 figures

Journal ref: J. Phys. Chem. C (2023)

Spatio-temporal dynamics of anisotropic emission from nano second laser produced aluminium plasma

Authors: Geethika B. R., Jinto Thomas, Milaan Patel, Renjith Kumar R., Hem Chandra Joshi

Abstract: Polarized emission carries captivating information and can help understand various elementary processes involving collisions within the plasma as well as in radiative transitions. In this work, we investigate the spatio-temporal dependence of the emission anisotropy of a nanosecond laser produced aluminium plasma at 100 mbar background pressure. We observe that the anisotropy of the emission spect… ▽ More Polarized emission carries captivating information and can help understand various elementary processes involving collisions within the plasma as well as in radiative transitions. In this work, we investigate the spatio-temporal dependence of the emission anisotropy of a nanosecond laser produced aluminium plasma at 100 mbar background pressure. We observe that the anisotropy of the emission spectra exhibits interesting spatio-temporal characteristics which in turn depend on the charge state of the emitting species. The degree of polarization (DOP) is found to reverse its sign along the plume propagation direction. Observed behaviour in DOP appears to be due to the contribution from various involved atomic processes. However, closer to the sample the contribution from the self-generated magnetic field predominantly affect the polarization. On the other hand, the effect of the self generated magnetic field on the observed polarized emission is insignificant as the plume propagates away from the sample. This is of particular interest in polarization resolved laser induced breakdown spectroscopy as spatio-temporal profile of the degree of polarization has to be properly taken into account prior to the spectral analysis. △ Less

Submitted 20 September, 2023; originally announced September 2023.

Shielded ionisation discharge (SID) probe for spatio-temporal profiling of pulsed molecular beam

Authors: Milaan Patel, Jinto Thomas, Hem Chandra Joshi

Abstract: In this work we report a shielded ionization discharge (SID) probe which is conceptualized, designed and implemented for measuring temporal and spatial density profiles in a pulsed molecular beam. The probe detects and provides profiles of neutrals of the molecular beam using small discharge which is assisted by the thermionic emission of electrons from a hot filament. In this article, design and… ▽ More In this work we report a shielded ionization discharge (SID) probe which is conceptualized, designed and implemented for measuring temporal and spatial density profiles in a pulsed molecular beam. The probe detects and provides profiles of neutrals of the molecular beam using small discharge which is assisted by the thermionic emission of electrons from a hot filament. In this article, design and characterisation of the developed probe are discussed. The performance of the probe is demonstrated by measuring the spatio-temporal profile of a 1.5 ms pulsed supersonic molecular beam. The suggested SID probe can be used to characterize and optimise the pulsed molecular beam source used in tokamak fueling, SMBI plasma diagnostics, ion beam profile monitors, cluster beam experiments, chemical kinetics, and other supersoinc beam related applications. △ Less

Submitted 19 April, 2023; originally announced April 2023.

Quantum Interference Enhances the Performance of Single-Molecule Transistors

Authors: Zhixin Chen, Iain M. Grace, Steffen L. Woltering, Lina Chen, Alex Gee, Jonathan Baugh, G. Andrew D. Briggs, Lapo Bogani, Jan A. Mol, Colin J. Lambert, Harry L. Anderson, James O. Thomas

Abstract: An unresolved challenge facing electronics at a few-nm scale is that resistive channels start leaking due to quantum tunneling. This affects the performance of nanoscale transistors, with single-molecule devices displaying particularly low switching ratios and operating frequencies, combined with large subthreshold swings.1 The usual strategy to mitigate quantum effects has been to increase device… ▽ More An unresolved challenge facing electronics at a few-nm scale is that resistive channels start leaking due to quantum tunneling. This affects the performance of nanoscale transistors, with single-molecule devices displaying particularly low switching ratios and operating frequencies, combined with large subthreshold swings.1 The usual strategy to mitigate quantum effects has been to increase device complexity, but theory shows that if quantum effects are exploited correctly, they can simultaneously lower energy consumption and boost device performance.2-6 Here, we demonstrate experimentally how the performance of molecular transistors can be improved when the resistive channel contains two destructively-interfering waves. We use a zinc-porphyrin coupled to graphene electrodes in a three-terminal transistor device to demonstrate a >104 conductance-switching ratio, a subthreshold swing at the thermionic limit, a > 7 kHz operating frequency, and stability over >105 cycles. This performance is competitive with the best nanoelectronic transistors. We fully map the antiresonance interference features in conductance, reproduce the behaviour by density functional theory calculations, and trace back this high performance to the coupling between molecular orbitals and graphene edge states. These results demonstrate how the quantum nature of electron transmission at the nanoscale can enhance, rather than degrade, device performance, and highlight directions for future development of miniaturised electronics. △ Less

Submitted 17 April, 2023; originally announced April 2023.

Comments: 11 pages, 4 figures

Pattern Forming Mechanisms of Color Vision

Authors: Zily Burstein, David D. Reid, Peter J. Thomas, Jack D. Cowan

Abstract: While our understanding of the way single neurons process chromatic stimuli in the early visual pathway has advanced significantly in recent years, we do not yet know how these cells interact to form stable representations of hue. Drawing on physiological studies, we offer a dynamical model of how the primary visual cortex tunes for color, hinged on intracortical interactions and emergent network… ▽ More While our understanding of the way single neurons process chromatic stimuli in the early visual pathway has advanced significantly in recent years, we do not yet know how these cells interact to form stable representations of hue. Drawing on physiological studies, we offer a dynamical model of how the primary visual cortex tunes for color, hinged on intracortical interactions and emergent network effects. After detailing the evolution of network activity through analytical and numerical approaches, we discuss the effects of the model's cortical parameters on the selectivity of the tuning curves. In particular, we explore the role of the model's thresholding nonlinearity in enhancing hue selectivity by expanding the region of stability, allowing for the precise encoding of chromatic stimuli in early vision. Finally, in the absence of a stimulus, the model is capable of explaining hallucinatory color perception via a Turing-like mechanism of biological pattern formation. △ Less

Submitted 15 April, 2023; originally announced April 2023.

Comments: 21 pages, 15 figures

The ESSnuSB design study: overview and future prospects

Authors: ESSnuSB Collaboration, A. Alekou, E. Baussan, A. K. Bhattacharyya, N. Blaskovic Kraljevic, M. Blennow, M. Bogomilov, B. Bolling, E. Bouquerel, F. Bramati, A. Branca, O. Buchan, A. Burgman, C. J. Carlile, J. Cederkall, S. Choubey, P. Christiansen, M. Collins, E. Cristaldo Morales, L. D'Alessi, H. Danared, D. Dancila, J. P. A. M. de André, J. P. Delahaye, M. Dracos , et al. (61 additional authors not shown)

Abstract: ESSnuSB is a design study for an experiment to measure the CP violation in the leptonic sector at the second neutrino oscillation maximum using a neutrino beam driven by the uniquely powerful ESS linear accelerator. The reduced impact of systematic errors on sensitivity at the second maximum allows for a very precise measurement of the CP violating parameter. This review describes the fundamental… ▽ More ESSnuSB is a design study for an experiment to measure the CP violation in the leptonic sector at the second neutrino oscillation maximum using a neutrino beam driven by the uniquely powerful ESS linear accelerator. The reduced impact of systematic errors on sensitivity at the second maximum allows for a very precise measurement of the CP violating parameter. This review describes the fundamental advantages of measurement at the 2nd maximum, the necessary upgrades to the ESS linac in order to produce a neutrino beam, the near and far detector complexes, the expected physics reach of the proposed ESSnuSB experiment, concluding with the near future developments aimed at the project realization. △ Less

Submitted 8 August, 2023; v1 submitted 30 March, 2023; originally announced March 2023.

Comments: 19 pages, 12 figures; Final version after review by the Universe journal

Challenges in low losses and large acceptance ion beam transport

Authors: F Osswald, E Traykov, T Durand, M Heine, J Michaud, J C Thomas

Abstract: A prototype of ion beam transport module has been developed at the Institut Pluridisciplinaire Hubert Curien (IPHC) and used as a test bed to investigate key issues related to the efficient transport of ion beams. This includes the reduction of the beam losses, the increase of the acceptance, and the definition of the instrumentation necessary to evaluate the performances. An experiment was perfor… ▽ More A prototype of ion beam transport module has been developed at the Institut Pluridisciplinaire Hubert Curien (IPHC) and used as a test bed to investigate key issues related to the efficient transport of ion beams. This includes the reduction of the beam losses, the increase of the acceptance, and the definition of the instrumentation necessary to evaluate the performances. An experiment was performed on a full-scale beam line and following a standard beam analysis, steering, and focusing procedure. After a review of the developments carried out for some demanding facilities and for the design of the quadrupoles implemented in the transport module, the paper highlights the challenge of measuring the preservation of transverse phase-space distributions with large acceptance conditions, i.e. with the highest ratio of beam filling to quadrupole aperture. Then, the tolerance to the errors and mitigation of the risks are discussed, in particular by considering the electric stability of the transport module, beam trips, behavior of the tail and the halo, and misalignment errors. △ Less

Submitted 13 March, 2023; originally announced March 2023.

Comments: arXiv admin note: substantial text overlap with arXiv:2211.09611

Review On Laser Induced Breakdown spectroscopy: Methodology and Technical Developments

Authors: Jinto Thomas, Hem Chandra Joshi

Abstract: In this review we attempt to provide a brief account of laser induced breakdown spectroscopy (LIBS) methodology and technological developments. We also summarise various methods adopted for exploiting LIBS. Besides, a brief overview of combination of LIBS in conjunction with other methods is also given. In this review we attempt to provide a brief account of laser induced breakdown spectroscopy (LIBS) methodology and technological developments. We also summarise various methods adopted for exploiting LIBS. Besides, a brief overview of combination of LIBS in conjunction with other methods is also given. △ Less

Submitted 26 February, 2023; originally announced February 2023.

Experimental investigation of free jets through supersonic nozzles

Authors: Milaan Patel, Jinto Thomas, Hem Chandra Joshi

Abstract: In this paper, we report experimental investigation to improve the shape of a supersonic nozzle for rarefied flows to generate high axial density at extended distances from the nozzle. The reported work is significant for molecular jet/beam applications that require high center-line density and narrow jet profile. We investigate a parabolic nozzle whose profile is generated using the virtual sourc… ▽ More In this paper, we report experimental investigation to improve the shape of a supersonic nozzle for rarefied flows to generate high axial density at extended distances from the nozzle. The reported work is significant for molecular jet/beam applications that require high center-line density and narrow jet profile. We investigate a parabolic nozzle whose profile is generated using the virtual source model of free expansion and compare its performance with a set of conical nozzles having different cone angles using simulations as well as experiments. All nozzles are made by additive manufacturing using ABS and performance is found to be satisfactory. Axial density and lateral spread of the jets are measured using a pitot tube assembly. The accuracy and operational limit of the pitot tube for rarefied flow is quantified by using established mathematical and empirical models for a sonic nozzle. The study demonstrates that the performance of the parabolic nozzle is comparable or slightly better as compared to conical counterparts. Moreover, the parabolic profile can be used for optimizing the opening angle for conical nozzles of various lengths. △ Less

Submitted 1 December, 2022; originally announced December 2022.

Particle Physics at the European Spallation Source

Authors: H. Abele, A. Alekou, A. Algora, K. Andersen, S. Baessler, L. Barron-Palos, J. Barrow, E. Baussan, P. Bentley, Z. Berezhiani, Y. Bessler, A. K. Bhattacharyya, A. Bianchi, J. Bijnens, C. Blanco, N. Blaskovic Kraljevic, M. Blennow, K. Bodek, M. Bogomilov, C. Bohm, B. Bolling, E. Bouquerel, G. Brooijmans, L. J. Broussard, O. Buchan , et al. (154 additional authors not shown)

Abstract: Presently under construction in Lund, Sweden, the European Spallation Source (ESS) will be the world's brightest neutron source. As such, it has the potential for a particle physics program with a unique reach and which is complementary to that available at other facilities. This paper describes proposed particle physics activities for the ESS. These encompass the exploitation of both the neutrons… ▽ More Presently under construction in Lund, Sweden, the European Spallation Source (ESS) will be the world's brightest neutron source. As such, it has the potential for a particle physics program with a unique reach and which is complementary to that available at other facilities. This paper describes proposed particle physics activities for the ESS. These encompass the exploitation of both the neutrons and neutrinos produced at the ESS for high precision (sensitivity) measurements (searches). △ Less

Submitted 30 January, 2024; v1 submitted 18 November, 2022; originally announced November 2022.

Comments: 121 pages, updated version after referee comments

Green beam lines, a challenging concept

Authors: F. Osswald, E. Traykov, T. Durand, M. Heine, J. Michaud, J. C. Thomas

Abstract: Due to increasing environmental and economic constraints, optimization of ion beam transport and equipment design becomes essential. The future should be equipped with planet-friendly facilities, that is, solutions that reduce environmental impact and improve economic competitiveness. The tendency to increase the intensity of the current and the power of the beams obliges us and brings us to new c… ▽ More Due to increasing environmental and economic constraints, optimization of ion beam transport and equipment design becomes essential. The future should be equipped with planet-friendly facilities, that is, solutions that reduce environmental impact and improve economic competitiveness. The tendency to increase the intensity of the current and the power of the beams obliges us and brings us to new challenges. Installations tend to have larger dimensions with increased areas, volumes, weights and costs. A new ion beam transport prototype was developed and used as a test bed to identify key issues to reduce beam losses and preserve transverse phase-space distributions with large acceptance conditions. △ Less

Submitted 17 November, 2022; originally announced November 2022.

Transverse emittance measurement in 2D and 4D performed on a Low Energy Beam Transport line: benchmarking and data analysis

Authors: F Osswald, T Durand, M Heine, J Michaud, F Poirier, J C Thomas, E Traykov

Abstract: 2D and 4D transverse phase-space of a low-energy ion-beam is measured with two of the most common emittance scanners. The article covers the description of the installation, the setup, the settings, the experiment and the benchmark of the two emittance meters. We compare the results from three series of measurements and present the advantages and drawbacks of the two systems. Coupling between phas… ▽ More 2D and 4D transverse phase-space of a low-energy ion-beam is measured with two of the most common emittance scanners. The article covers the description of the installation, the setup, the settings, the experiment and the benchmark of the two emittance meters. We compare the results from three series of measurements and present the advantages and drawbacks of the two systems. Coupling between phase-space planes, correlations and mitigation of deleterious effects are discussed. The influence of background noise and aberrations of trace-space figures on emittance measurements and RMS calculations is highlighted, especially for low density beams and halos. A new data analysis method using noise reduction, filtering, and reconstruction of the emittance figure is described. Finally, some basic concepts of phase-space theory and application to beam transport are recalled. △ Less

Submitted 9 November, 2022; originally announced November 2022.

ATHENA Detector Proposal -- A Totally Hermetic Electron Nucleus Apparatus proposed for IP6 at the Electron-Ion Collider

Authors: ATHENA Collaboration, J. Adam, L. Adamczyk, N. Agrawal, C. Aidala, W. Akers, M. Alekseev, M. M. Allen, F. Ameli, A. Angerami, P. Antonioli, N. J. Apadula, A. Aprahamian, W. Armstrong, M. Arratia, J. R. Arrington, A. Asaturyan, E. C. Aschenauer, K. Augsten, S. Aune, K. Bailey, C. Baldanza, M. Bansal, F. Barbosa, L. Barion , et al. (415 additional authors not shown)

Abstract: ATHENA has been designed as a general purpose detector capable of delivering the full scientific scope of the Electron-Ion Collider. Careful technology choices provide fine tracking and momentum resolution, high performance electromagnetic and hadronic calorimetry, hadron identification over a wide kinematic range, and near-complete hermeticity. This article describes the detector design and its e… ▽ More ATHENA has been designed as a general purpose detector capable of delivering the full scientific scope of the Electron-Ion Collider. Careful technology choices provide fine tracking and momentum resolution, high performance electromagnetic and hadronic calorimetry, hadron identification over a wide kinematic range, and near-complete hermeticity. This article describes the detector design and its expected performance in the most relevant physics channels. It includes an evaluation of detector technology choices, the technical challenges to realizing the detector and the R&D required to meet those challenges. △ Less

Submitted 13 October, 2022; originally announced October 2022.

Journal ref: JINST 17 (2022) 10, P10019

Searching For Dark Matter with Plasma Haloscopes

Authors: Alexander J. Millar, Steven M. Anlage, Rustam Balafendiev, Pavel Belov, Karl van Bibber, Jan Conrad, Marcel Demarteau, Alexander Droster, Katherine Dunne, Andrea Gallo Rosso, Jon E. Gudmundsson, Heather Jackson, Gagandeep Kaur, Tove Klaesson, Nolan Kowitt, Matthew Lawson, Alexander Leder, Akira Miyazaki, Sid Morampudi, Hiranya V. Peiris, Henrik S. Røising, Gaganpreet Singh, Dajie Sun, Jacob H. Thomas, Frank Wilczek , et al. (2 additional authors not shown)

Abstract: We summarise the recent progress of the Axion Longitudinal Plasma HAloscope (ALPHA) Consortium, a new experimental collaboration to build a plasma haloscope to search for axions and dark photons. The plasma haloscope is a novel method for the detection of the resonant conversion of light dark matter to photons. ALPHA will be sensitive to QCD axions over almost a decade of parameter space, potentia… ▽ More We summarise the recent progress of the Axion Longitudinal Plasma HAloscope (ALPHA) Consortium, a new experimental collaboration to build a plasma haloscope to search for axions and dark photons. The plasma haloscope is a novel method for the detection of the resonant conversion of light dark matter to photons. ALPHA will be sensitive to QCD axions over almost a decade of parameter space, potentially discovering dark matter and resolving the Strong CP problem. Unlike traditional cavity haloscopes, which are generally limited in volume by the Compton wavelength of the dark matter, plasma haloscopes use a wire metamaterial to create a tuneable artificial plasma frequency, decoupling the wavelength of light from the Compton wavelength and allowing for much stronger signals. We develop the theoretical foundations of plasma haloscopes and discuss recent experimental progress. Finally, we outline a baseline design for ALPHA and show that a full-scale experiment could discover QCD axions over almost a decade of parameter space. △ Less

Submitted 22 March, 2023; v1 submitted 30 September, 2022; originally announced October 2022.

Comments: Endorsers: Jens Dilling, Michael Febbraro, Stefan Knirck, and Claire Marvinney. 26 pages, 17 figures, version accepted in Physical Review D, typo corrected

Report number: FERMILAB-PUB-22-739-T

Journal ref: Physical Review D 107, 055013 (2023)

Monte Carlo method for constructing confidence intervals with unconstrained and constrained nuisance parameters in the NOvA experiment

Authors: M. A. Acero, B. Acharya, P. Adamson, L. Aliaga, N. Anfimov, A. Antoshkin, E. Arrieta-Diaz, L. Asquith, A. Aurisano, A. Back, C. Backhouse, M. Baird, N. Balashov, P. Baldi, B. A. Bambah, S. Bashar, A. Bat, K. Bays, R. Bernstein, V. Bhatnagar, D. Bhattarai, B. Bhuyan, J. Bian, A. C. Booth, R. Bowles , et al. (196 additional authors not shown)

Abstract: Measuring observables to constrain models using maximum-likelihood estimation is fundamental to many physics experiments. Wilks' theorem provides a simple way to construct confidence intervals on model parameters, but it only applies under certain conditions. These conditions, such as nested hypotheses and unbounded parameters, are often violated in neutrino oscillation measurements and other expe… ▽ More Measuring observables to constrain models using maximum-likelihood estimation is fundamental to many physics experiments. Wilks' theorem provides a simple way to construct confidence intervals on model parameters, but it only applies under certain conditions. These conditions, such as nested hypotheses and unbounded parameters, are often violated in neutrino oscillation measurements and other experimental scenarios. Monte Carlo methods can address these issues, albeit at increased computational cost. In the presence of nuisance parameters, however, the best way to implement a Monte Carlo method is ambiguous. This paper documents the method selected by the NOvA experiment, the profile construction. It presents the toy studies that informed the choice of method, details of its implementation, and tests performed to validate it. It also includes some practical considerations which may be of use to others choosing to use the profile construction. △ Less

Submitted 24 January, 2025; v1 submitted 28 July, 2022; originally announced July 2022.

Comments: 28 pages, 14 figures

Report number: FERMILAB-PUB-22-476-ND

Journal ref: 2025 JINST 20 T02001

Neutrino Characterisation using Convolutional Neural Networks in CHIPS water Cherenkov detectors

Authors: Josh Tingey, Simeon Bash, John Cesar, Thomas Dodwell, Stefano Germani, Paul Kooijman, Petr Mánek, Mustafa Ozkaynak, Andy Perch, Jennifer Thomas, Leigh Whitehead

Abstract: This work presents a novel approach to water Cherenkov neutrino detector event reconstruction and classification. Three forms of a Convolutional Neural Network have been trained to reject cosmic muon events, classify beam events, and estimate neutrino energies, using only a slightly modified version of the raw detector event as input. When evaluated on a realistic selection of simulated CHIPS-5kto… ▽ More This work presents a novel approach to water Cherenkov neutrino detector event reconstruction and classification. Three forms of a Convolutional Neural Network have been trained to reject cosmic muon events, classify beam events, and estimate neutrino energies, using only a slightly modified version of the raw detector event as input. When evaluated on a realistic selection of simulated CHIPS-5kton prototype detector events, this new approach significantly increases performance over the standard likelihood-based reconstruction and simple neural network classification. △ Less

Submitted 29 June, 2022; originally announced June 2022.

Comments: 45 pages, 22 figures, 5 tables, to be submitted to Nuclear Instruments and Methods in Physics Research - section A

The European Spallation Source neutrino Super Beam Conceptual Design Report

Authors: A. Alekou, E. Baussan, A. K. Bhattacharyya, N. Blaskovic Kraljevic, M. Blennow, M. Bogomilov, B. Bolling, E. Bouquerel, O. Buchan, A. Burgman, C. J. Carlile, J. Cederkall, P. Christiansen, M. Collins, E. Cristaldo Morales, P. Cupiał, L. D'Alessi, H. Danared, D. Dancila, J. P. A. M. de André, J. P. Delahaye, M. Dracos, I. Efthymiopoulos, T. Ekelöf, M. Eshraqi , et al. (51 additional authors not shown)

Abstract: This conceptual design report provides a detailed account of the European Spallation Source neutrino Super Beam (ESS$ν$SB) feasibility study. This facility has been proposed after the measurements reported in 2012 of a relatively large value of the neutrino mixing angle $θ_{13}$, which raised the possibility of observing potential CP violation in the leptonic sector with conventional neutrino beam… ▽ More This conceptual design report provides a detailed account of the European Spallation Source neutrino Super Beam (ESS$ν$SB) feasibility study. This facility has been proposed after the measurements reported in 2012 of a relatively large value of the neutrino mixing angle $θ_{13}$, which raised the possibility of observing potential CP violation in the leptonic sector with conventional neutrino beams. The measured value of $θ_{13}$ also privileges the $2^{nd}$ oscillation maximum for the discovery of CP violation instead of the more typically studied $1^{st}$ maximum. The sensitivity at this $2^{nd}$ oscillation maximum is about three times higher than at the $1^{st}$ one, which implies a reduced influence of systematic errors. Working at the $2^{nd}$ oscillation maximum requires a very intense neutrino beam with an appropriate energy. The world's most intense pulsed spallation neutron source, the European Spallation Source (ESS), will have a proton linac operating at 5\,MW power, 2\,GeV kinetic energy and 14~Hz repetition rate (3~ms pulse duration, 4\% duty cycle) for neutron production. In this design study it is proposed to double the repetition rate and compress the beam pulses to the level of microseconds in order to provide an additional 5~MW proton beam for neutrino production. The physics performance has been evaluated for such a neutrino super beam, in conjunction with a megaton-scale underground water Cherenkov neutrino detector installed at a distance of 360--550\,km from ESS. The ESS proton linac upgrades, the accumulator ring required for proton-pulse compression, the target station design and optimisation, the near and far detector complexes, and the physics potential of the facility are all described in this report. The ESS linac will be operational by 2025, at which point the implementation of upgrades for the neutrino facility could begin. △ Less

Submitted 2 June, 2022; originally announced June 2022.

Comments: 216 pages

Phase-Coherent Charge Transport through a Porphyrin Nanoribbon

Authors: Zhixin Chen, Jie-Ren Deng, Songjun Hou, Xinya Bian, Jacob L. Swett, Qingqing Wu, Jonathan Baugh, G. Andrew D. Briggs, Jan A. Mol, Colin J. Lambert, Harry L. Anderson, James O. Thomas

Abstract: Quantum interference in nano-electronic devices could lead to reduced-energy computing and efficient thermoelectric energy harvesting. When devices are shrunk down to the molecular level it is still unclear to what extent electron transmission is phase coherent, as molecules usually act as scattering centres, without the possibility of showing particle-wave duality. Here we show electron transmiss… ▽ More Quantum interference in nano-electronic devices could lead to reduced-energy computing and efficient thermoelectric energy harvesting. When devices are shrunk down to the molecular level it is still unclear to what extent electron transmission is phase coherent, as molecules usually act as scattering centres, without the possibility of showing particle-wave duality. Here we show electron transmission remains phase coherent in molecular porphyrin nanoribbons, synthesized with perfectly defined geometry, connected to graphene electrodes. The device acts as a graphene Fabry-Pérot interferometer, allowing direct probing of the transport mechanisms throughout several regimes, including the Kondo one. Electrostatic gating allows measurement of the molecular conductance in multiple molecular oxidation states, demonstrating a thousand-fold increase of the current by interference, and unravelling molecular and graphene transport pathways. These results demonstrate a platform for the use of interferometric effects in single-molecule junctions, opening up new avenues for studying quantum coherence in molecular electronic and spintronic devices. △ Less

Submitted 5 September, 2022; v1 submitted 17 May, 2022; originally announced May 2022.

Comments: 14 pages, 3 figures