Showing 1–30 of 30 results for author: Chen, J H

On the $\mathrm{In_{x}Ga_{1-x}As}$ channel noise in InP HEMTs from 4 K to 300 K

Authors: Junjie Li, Justin H. Chen, Austin J. Minnich, Jan Grahn

Abstract: The InP high-electron-mobility transistor (HEMT) is indispensable for low-noise amplifiers (LNAs) in radio astronomy and quantum computing. The composition of the $\mathrm{In_{x}Ga_{1-x}As}$ channel in InP HEMT is known to influence the LNA noise performance. However, the various physical mechanisms responsible for noise generation are not fully characterized and understood. Here, we investigate t… ▽ More The InP high-electron-mobility transistor (HEMT) is indispensable for low-noise amplifiers (LNAs) in radio astronomy and quantum computing. The composition of the $\mathrm{In_{x}Ga_{1-x}As}$ channel in InP HEMT is known to influence the LNA noise performance. However, the various physical mechanisms responsible for noise generation are not fully characterized and understood. Here, we investigate the $\mathrm{In_{x}Ga_{1-x}As}$ channel noise from 4 K to 300 K for 100-nm gate-length InP HEMTs with channel indium content of 53\%, 60\% and 70\%. Channel noise was quantified by extracting the equivalent drain noise temperature $\mathit{T}_{d}$ using both on-wafer and LNA-based measurements, covering 40-300 K and 4-40 K, respectively. The 60\% indium channel InP HEMT exhibited the lowest channel noise across the full temperature range. The $\mathit{T}_{d}$ extracted from on-wafer characterization was found to obey a parabolic temperature dependence which predicted the $\mathit{T}_{d}$ at 4 K for all InP HEMTs in good agreement with LNA-based measurements. By expressing the channel noise as the sum of one thermal and one excess noise term, it was found that the former increased linearly with ambient temperature and dominated at 300 K. The channel noise at 4 K was determined by the excess noise term and exhibited a non-monotonic dependence on the channel indium content in the InP HEMT. The results suggest that the excess noise in the InP HEMT originates not only from temperature-independent shot noise but also from impact ionization and real-space transfer noise. △ Less

Submitted 6 July, 2026; originally announced July 2026.

Studies of Neutrino-Nucleus Elastic Scattering with Point-Contact Germanium Detectors at the Kuo-Sheng Reactor Neutrino Laboratory

Authors: TEXONO Collaboration, M. K. Singh, S. Karmakar, Greeshma C., H. B. Li, F. K. Lin, V. Sharma, L. Singh, H. T. Wong, L. T. Yang, M. Agartioglu, J. H. Chen, J. W. Chen, C. I. Chiang, M. Deniz, T. Guo, H. C. Hsu, W. H. Kao, S. Karadaǧ, J. B. Legras, C. H. Leung, J. Li, T. Y. Liang, S. T. Lin, S. K. Liu , et al. (14 additional authors not shown)

Abstract: The low energy and intense flux of electron anti-neutrinos from nuclear reactors provide the perfect stage to study elastic neutrino-nucleus scattering ($νA_{el}$) in the fully coherent regime. We report results from the TEXONO experiment using electro-cooled $p$-type point-contact Germanium detectors with masses of 523~g and 1434~g at the Kuo-Sheng Reactor Neutrino Laboratory. We report improved… ▽ More The low energy and intense flux of electron anti-neutrinos from nuclear reactors provide the perfect stage to study elastic neutrino-nucleus scattering ($νA_{el}$) in the fully coherent regime. We report results from the TEXONO experiment using electro-cooled $p$-type point-contact Germanium detectors with masses of 523~g and 1434~g at the Kuo-Sheng Reactor Neutrino Laboratory. We report improved constraints on the $νA_{el}$ cross section with a combined exposure of 404(813.7)~kg-days of Reactor ON(OFF) data at an electron-equivalent threshold of 200~eV$_{ee}$. The Lindhard model, in which the quenching factor is parameterized by a single parameter k, is adopted to describe the suppression of ionization yield. At the benchmark value of k=0.162, a limit of $ρ<$2.0 at 90\% confidence level (CL) is derived, where $ρ$ represents the ratio of the observed to the predicted Standard Model cross section. Moreover the region k$>$0.205 is excluded at 90\% CL using the SM-predicted $νA_{el}$ rate. A bound on the neutrino magnetic moment from $νA_{el}$ at $μ_ν {<} 5.9 \times 10^{-10}~μ_B$ at 90\% CL is also derived. △ Less

Submitted 15 June, 2026; originally announced June 2026.

Comments: 21 pages, 19 figures

Scaling Laws for Thermodiffusively Unstable Lean Premixed Turbulent Hydrogen-Air Flames

Authors: M. Gauding T. Lehmann, T. L. Howarth, L. Berger, M. Rieth, A. Gruber, W. Song, J. H. Chen, M. Day, A. Attili, E. F. Hunt, A. J. Aspden, H. Pitsch

Abstract: Lean premixed hydrogen-air flames are strongly affected by thermodiffusive (TD) instabilities, which can alter the flame structure and enhance the local reactivity many-fold. Two recent models (Howarth et al. (Combust.~Flame 253, 2023) and Rieth et al. (MSC 2023)) describe the scaling of the stretch factor in turbulent hydrogen flames with the Karlovitz number using different parameters, i.e., the… ▽ More Lean premixed hydrogen-air flames are strongly affected by thermodiffusive (TD) instabilities, which can alter the flame structure and enhance the local reactivity many-fold. Two recent models (Howarth et al. (Combust.~Flame 253, 2023) and Rieth et al. (MSC 2023)) describe the scaling of the stretch factor in turbulent hydrogen flames with the Karlovitz number using different parameters, i.e., the $ω_2$ parameter from linear stability theory and the ratio of the Zel'dovich to the Peclet number (${Ze}/{Pe}$). Using a comprehensive set of 91 direct numerical simulation (DNS) cases spanning a wide range of pressures, equivalence ratios, turbulence intensities, and flow configurations, both formulations are systematically evaluated and an adapted formulation is proposed. The analysis of the governing non-dimensional groups reveals a scaling behavior characterized by two distinct regimes. In the first regime, typically relevant for burner and gas turbine conditions, both models reduce to an identical form that depends solely on the Karlovitz number and the stretch factor of laminar flames, independent of $ω_2$ or ${Ze}/{Pe}$. In the second regime, characterized by ultra-low flame speeds, the explicit consideration of $ω_2$ or the ratio ${Ze}/{Pe}$ is required for accurate scaling. In both regimes, the two models predict the DNS data reasonably well and reduce to the same functional form of non-dimensional groups, indicating their physical equivalence. △ Less

Submitted 27 March, 2026; originally announced March 2026.

Multi-channel, multi-template event reconstruction for SuperCDMS data using machine learning

Authors: M. F. Albakry, I. Alkhatib, D. Alonso-Gonzalez, J. Anczarski, T. Aralis, T. Aramaki, I. Ataee Langroudy, C. Bathurst, R. Bhattacharyya, A. J. Biff, P. L. Brink, M. Buchanan, R. Bunker, B. Cabrera, R. Calkins, R. A. Cameron, C. Cartaro, D. G. Cerdeno, Y. -Y. Chang, M. Chaudhuri, J. H. Chen, R. Chen, N. Chott, J. Cooley, H. Coombes , et al. (117 additional authors not shown)

Abstract: SuperCDMS SNOLAB uses kilogram-scale germanium and silicon detectors to search for dark matter. Each detector has Transition Edge Sensors (TESs) patterned on the top and bottom faces of a large crystal substrate, with the TESs electrically grouped into six phonon readout channels per face. Noise correlations are expected among a detector's readout channels, in part because the channels and their r… ▽ More SuperCDMS SNOLAB uses kilogram-scale germanium and silicon detectors to search for dark matter. Each detector has Transition Edge Sensors (TESs) patterned on the top and bottom faces of a large crystal substrate, with the TESs electrically grouped into six phonon readout channels per face. Noise correlations are expected among a detector's readout channels, in part because the channels and their readout electronics are located in close proximity to one another. Moreover, owing to the large size of the detectors, energy deposits can produce vastly different phonon propagation patterns depending on their location in the substrate, resulting in a strong position dependence in the readout-channel pulse shapes. Both of these effects can degrade the energy resolution and consequently diminish the dark matter search sensitivity of the experiment if not accounted for properly. We present a new algorithm for pulse reconstruction, mathematically formulated to take into account correlated noise and pulse shape variations. This new algorithm fits N readout channels with a superposition of M pulse templates simultaneously - hence termed the N$\times$M filter. We describe a method to derive the pulse templates using principal component analysis (PCA) and to extract energy and position information using a gradient boosted decision tree (GBDT). We show that these new N$\times$M and GBDT analysis tools can reduce the impact from correlated noise sources while improving the reconstructed energy resolution for simulated mono-energetic events by more than a factor of three and for the 71Ge K-shell electron-capture peak recoils measured in a previous version of SuperCDMS called CDMSlite to $<$ 50 eV from the previously published value of $\sim$100 eV. These results lay the groundwork for position reconstruction in SuperCDMS with the N$\times$M outputs. △ Less

Submitted 27 August, 2025; originally announced August 2025.

Comments: 22 pages, 8 figures

Probabilistic transfer learning methodology to expedite high fidelity simulation of reactive flows

Authors: Bruno S. Soriano, Ki Sung Jung, Tarek Echekki, Jacqueline H. Chen, Mohammad Khalil

Abstract: Reduced order models based on the transport of a lower dimensional manifold representation of the thermochemical state, such as Principal Component (PC) transport and Machine Learning (ML) techniques, have been developed to reduce the computational cost associated with the Direct Numerical Simulations (DNS) of reactive flows. Both PC transport and ML normally require an abundance of data to exhibi… ▽ More Reduced order models based on the transport of a lower dimensional manifold representation of the thermochemical state, such as Principal Component (PC) transport and Machine Learning (ML) techniques, have been developed to reduce the computational cost associated with the Direct Numerical Simulations (DNS) of reactive flows. Both PC transport and ML normally require an abundance of data to exhibit sufficient predictive accuracy, which might not be available due to the prohibitive cost of DNS or experimental data acquisition. To alleviate such difficulties, similar data from an existing dataset or domain (source domain) can be used to train ML models, potentially resulting in adequate predictions in the domain of interest (target domain). This study presents a novel probabilistic transfer learning (TL) framework to enhance the trust in ML models in correctly predicting the thermochemical state in a lower dimensional manifold and a sparse data setting. The framework uses Bayesian neural networks, and autoencoders, to reduce the dimensionality of the state space and diffuse the knowledge from the source to the target domain. The new framework is applied to one-dimensional freely-propagating flame solutions under different data sparsity scenarios. The results reveal that there is an optimal amount of knowledge to be transferred, which depends on the amount of data available in the target domain and the similarity between the domains. TL can reduce the reconstruction error by one order of magnitude for cases with large sparsity. The new framework required 10 times less data for the target domain to reproduce the same error as in the abundant data scenario. Furthermore, comparisons with a state-of-the-art deterministic TL strategy show that the probabilistic method can require four times less data to achieve the same reconstruction error. △ Less

Submitted 17 May, 2024; originally announced May 2024.

The BM@N spectrometer at the NICA accelerator complex

Authors: S. Afanasiev, G. Agakishiev, E. Aleksandrov, I. Aleksandrov, P. Alekseev, K. Alishina, V. Astakhov, E. Atkin, T. Aushev, V. Azorskiy, V. Babkin, N. Balashov, R. Barak, A. Baranov, D. Baranov, N. Baranova, N. Barbashina, M. Baznat, S. Bazylev, M. Belov, D. Blau, V. Bocharnikov, G. Bogdanova, A. Bolozdynya, E. Bondar , et al. (187 additional authors not shown)

Abstract: BM@N (Baryonic Matter at Nuclotron) is the first experiment operating and taking data at the Nuclotron/NICA ion-accelerating complex.The aim of the BM@N experiment is to study interactions of relativistic heavy-ion beams with fixed targets. We present a technical description of the BM@N spectrometer including all its subsystems. BM@N (Baryonic Matter at Nuclotron) is the first experiment operating and taking data at the Nuclotron/NICA ion-accelerating complex.The aim of the BM@N experiment is to study interactions of relativistic heavy-ion beams with fixed targets. We present a technical description of the BM@N spectrometer including all its subsystems. △ Less

Submitted 11 March, 2024; v1 submitted 29 December, 2023; originally announced December 2023.

Comments: 34 pages, 47 figures, 6 tables

Transfer learning for predicting source terms of principal component transport in chemically reactive flow

Authors: Ki Sung Jung, Tarek Echekki, Jacqueline H. Chen, Mohammad Khalil

Abstract: The objective of this study is to evaluate whether the number of requisite training samples can be reduced with the use of various transfer learning models for predicting, for example, the chemical source terms of the data-driven reduced-order model that represents the homogeneous ignition process of a hydrogen/air mixture. Principal component analysis is applied to reduce the dimensionality of th… ▽ More The objective of this study is to evaluate whether the number of requisite training samples can be reduced with the use of various transfer learning models for predicting, for example, the chemical source terms of the data-driven reduced-order model that represents the homogeneous ignition process of a hydrogen/air mixture. Principal component analysis is applied to reduce the dimensionality of the hydrogen/air mixture in composition space. Artificial neural networks (ANNs) are used to tabulate the reaction rates of principal components, and subsequently, a system of ordinary differential equations is solved. As the number of training samples decreases at the target task (i.e.,for T0 > 1000 K and various phi), the reduced-order model fails to predict the ignition evolution of a hydrogen/air mixture. Three transfer learning strategies are then applied to the training of the ANN model with a sparse dataset. The performance of the reduced-order model with a sparse dataset is found to be remarkably enhanced if the training of the ANN model is restricted by a regularization term that controls the degree of knowledge transfer from source to target tasks. To this end, a novel transfer learning method is introduced, parameter control via partial initialization and regularization (PaPIR), whereby the amount of knowledge transferred is systemically adjusted for the initialization and regularization of the ANN model in the target task. It is found that an additional performance gain can be achieved by changing the initialization scheme of the ANN model in the target task when the task similarity between source and target tasks is relatively low. △ Less

Submitted 1 December, 2023; originally announced December 2023.

Comments: 41 pages, 14 figures

Journal ref: DCE 5 (2024) e42

Turbulence in Focus: Benchmarking Scaling Behavior of 3D Volumetric Super-Resolution with BLASTNet 2.0 Data

Authors: Wai Tong Chung, Bassem Akoush, Pushan Sharma, Alex Tamkin, Ki Sung Jung, Jacqueline H. Chen, Jack Guo, Davy Brouzet, Mohsen Talei, Bruno Savard, Alexei Y. Poludnenko, Matthias Ihme

Abstract: Analysis of compressible turbulent flows is essential for applications related to propulsion, energy generation, and the environment. Here, we present BLASTNet 2.0, a 2.2 TB network-of-datasets containing 744 full-domain samples from 34 high-fidelity direct numerical simulations, which addresses the current limited availability of 3D high-fidelity reacting and non-reacting compressible turbulent f… ▽ More Analysis of compressible turbulent flows is essential for applications related to propulsion, energy generation, and the environment. Here, we present BLASTNet 2.0, a 2.2 TB network-of-datasets containing 744 full-domain samples from 34 high-fidelity direct numerical simulations, which addresses the current limited availability of 3D high-fidelity reacting and non-reacting compressible turbulent flow simulation data. With this data, we benchmark a total of 49 variations of five deep learning approaches for 3D super-resolution - which can be applied for improving scientific imaging, simulations, turbulence models, as well as in computer vision applications. We perform neural scaling analysis on these models to examine the performance of different machine learning (ML) approaches, including two scientific ML techniques. We demonstrate that (i) predictive performance can scale with model size and cost, (ii) architecture matters significantly, especially for smaller models, and (iii) the benefits of physics-based losses can persist with increasing model size. The outcomes of this benchmark study are anticipated to offer insights that can aid the design of 3D super-resolution models, especially for turbulence models, while this data is expected to foster ML methods for a broad range of flow physics applications. This data is publicly available with download links and browsing tools consolidated at https://blastnet.github.io. △ Less

Submitted 27 October, 2023; v1 submitted 23 September, 2023; originally announced September 2023.

Comments: Accepted in Adv. in Neural Information Processing Systems 36 (NeurIPS 2023). Link: https://nips.cc/virtual/2023/poster/73433 . 55 pages, 21 figures. Keywords: Super-resolution, 3D, Neural Scaling, Physics-informed Loss, Computational Fluid Dynamics, Partial Differential Equations, Turbulent Reacting Flows, Direct Numerical Simulation, Fluid Mechanics, Combustion, Computer Vision

Investigation of Cryogenic Current-Voltage Anomalies in SiGe HBTs: Role of Base-Emitter Junction Inhomogeneities

Authors: Nachiket R. Naik, Bekari Gabritchidze, Justin H. Chen, Jacob Kooi, Kieran A. Cleary, Austin J. Minnich

Abstract: The deviations of cryogenic collector current-voltage characteristics of SiGe heterojunction bipolar transistors (HBTs) from ideal drift-diffusion theory have been a topic of investigation for many years. Recent work indicates that direct tunneling across the base contributes to the non-ideal current in highly-scaled devices. However, cryogenic discrepancies have been observed even in older-genera… ▽ More The deviations of cryogenic collector current-voltage characteristics of SiGe heterojunction bipolar transistors (HBTs) from ideal drift-diffusion theory have been a topic of investigation for many years. Recent work indicates that direct tunneling across the base contributes to the non-ideal current in highly-scaled devices. However, cryogenic discrepancies have been observed even in older-generation devices for which direct tunneling is negligible, suggesting another mechanism may also contribute. Although similar non-ideal current-voltage characteristics have been observed in Schottky junctions and were attributed to spatial inhomogeneities in the base-emitter junction potential, this explanation has not been considered for SiGe HBTs. Here, we experimentally investigate this hypothesis by characterizing the collector current ideality factor and built-in potential of a SiGe HBT versus temperature using a cryogenic probe station. The temperature-dependence of the ideality factor and the relation between the built-in potential as measured by capacitance-voltage and current-voltage characteristics are in good qualitative agreement with the predictions of a theory of electrical transport across a junction with a Gaussian distribution of potential barrier heights. These observations suggest that lateral inhomogeneities in the base-emitter junction potential may contribute to the cryogenic non-idealities. This work helps to identify the physical mechanisms limiting the cryogenic microwave noise performance of SiGe HBTs. △ Less

Submitted 4 January, 2024; v1 submitted 27 February, 2023; originally announced February 2023.

The Bearable Lightness of Big Data: Towards Massive Public Datasets in Scientific Machine Learning

Authors: Wai Tong Chung, Ki Sung Jung, Jacqueline H. Chen, Matthias Ihme

Abstract: In general, large datasets enable deep learning models to perform with good accuracy and generalizability. However, massive high-fidelity simulation datasets (from molecular chemistry, astrophysics, computational fluid dynamics (CFD), etc. can be challenging to curate due to dimensionality and storage constraints. Lossy compression algorithms can help mitigate limitations from storage, as long as… ▽ More In general, large datasets enable deep learning models to perform with good accuracy and generalizability. However, massive high-fidelity simulation datasets (from molecular chemistry, astrophysics, computational fluid dynamics (CFD), etc. can be challenging to curate due to dimensionality and storage constraints. Lossy compression algorithms can help mitigate limitations from storage, as long as the overall data fidelity is preserved. To illustrate this point, we demonstrate that deep learning models, trained and tested on data from a petascale CFD simulation, are robust to errors introduced during lossy compression in a semantic segmentation problem. Our results demonstrate that lossy compression algorithms offer a realistic pathway for exposing high-fidelity scientific data to open-source data repositories for building community datasets. In this paper, we outline, construct, and evaluate the requirements for establishing a big data framework, demonstrated at https://blastnet.github.io/, for scientific machine learning. △ Less

Submitted 25 July, 2022; originally announced July 2022.

Comments: Accepted in ICML 2022 2nd AI for Science Workshop. 10 pages, 8 figures

Journal ref: ICML 2022 2nd AI for Science Workshop

Cosmogenic background study for a 100Mo-based bolometric demonstration experiment at China JinPing underground Laboratory

Authors: W. Chen, L. Ma, J. H. Chen, H. Z. Huang, Y. G. Ma

Abstract: We perform simulation study for a 10-kg $^{100}$Mo-based bolometeric demonstration experiment for neutrinoless double-beta decay ($0νββ$) search at China JinPing underground Laboratory (CJPL). Cosmogenic production of radionuclides in $^{100}$Mo-enriched lithium molybdate crystals and copper components of the detector system are studied using Geant4 toolkit based on the simulated cosmic ray data f… ▽ More We perform simulation study for a 10-kg $^{100}$Mo-based bolometeric demonstration experiment for neutrinoless double-beta decay ($0νββ$) search at China JinPing underground Laboratory (CJPL). Cosmogenic production of radionuclides in $^{100}$Mo-enriched lithium molybdate crystals and copper components of the detector system are studied using Geant4 toolkit based on the simulated cosmic ray data from the CRY library. Background energy spectra of the cosmogenic radionuclides including $^{56}$Co, $^{82}$Rb and $^{88}$Y which are harmful for the $^{100}$Mo-based $0νββ$ experiment are investigated. We then evaluate the total cosmogenic background level in the $^{100}$Mo $0νββ$ search energy region of interest (ROI) for the demonstration experiment. After one year of cooling down underground, the residual background contribution is found to be 1.8$\times$10$^{-6}$ cts/kg/keV/yr and 3.3$\times$10$^{-4}$ cts/kg/keV/yr from crystals and copper components, respectively. Furthermore, underground cosmogenic activation of copper and lithium molybdate crystal is calculated based on the simulation spectra of neutron and proton in CJPL. The underground cosmogenic background is found to be negligible in the ROI. △ Less

Submitted 18 June, 2022; originally announced June 2022.

Evaluation of finite difference based asynchronous partial differential equations solver for reacting flows

Authors: Komal Kumari, Emmet Cleary, Swapnil Desai, Diego A. Donzis, Jacqueline H. Chen, Konduri Aditya

Abstract: Next-generation exascale machines with extreme levels of parallelism will provide massive computing resources for large scale numerical simulations of complex physical systems at unprecedented parameter ranges. However, novel numerical methods, scalable algorithms and re-design of current state-of-the art numerical solvers are required for scaling to these machines with minimal overheads. One such… ▽ More Next-generation exascale machines with extreme levels of parallelism will provide massive computing resources for large scale numerical simulations of complex physical systems at unprecedented parameter ranges. However, novel numerical methods, scalable algorithms and re-design of current state-of-the art numerical solvers are required for scaling to these machines with minimal overheads. One such approach for partial differential equations based solvers involves computation of spatial derivatives with possibly delayed or asynchronous data using high-order asynchrony-tolerant (AT) schemes to facilitate mitigation of communication and synchronization bottlenecks without affecting the numerical accuracy. In the present study, an effective methodology of implementing temporal discretization using a multi-stage Runge-Kutta method with AT schemes is presented. Together these schemes are used to perform asynchronous simulations of canonical reacting flow problems, demonstrated in one-dimension including auto-ignition of a premixture, premixed flame propagation and non-premixed autoignition. Simulation results show that the AT schemes incur very small numerical errors in all key quantities of interest including stiff intermediate species despite delayed data at processing element (PE) boundaries. For simulations of supersonic flows, the degraded numerical accuracy of well-known shock-resolving WENO (weighted essentially non-oscillatory) schemes when used with relaxed synchronization is also discussed. To overcome this loss of accuracy, high-order AT-WENO schemes are derived and tested on linear and non-linear equations. Finally the novel AT-WENO schemes are demonstrated in the propagation of a detonation wave with delays at PE boundaries. △ Less

Submitted 3 April, 2022; originally announced April 2022.

Construction and commissioning of the collinear laser spectroscopy system at BRIF

Authors: S. J. Wang, X. F. Yang, S. W. Bai, Y. C. Liu, P. Zhang, Y. S. Liu, H. R. Hu, H. W. Li, B. Tang, B. Q. Cui, C. Y. He, X. Ma, Q. T. Li, J. H. Chen, K. Ma, L. S. Yang, Z. Y. Hu, W. L. Pu, Y. Chen, Y. F. Guo, Z. Y. Du, Z. Yan, F. L. Liu, H. R. Wang, G. Q. Yang , et al. (2 additional authors not shown)

Abstract: We have constructed a collinear laser spectroscopy (CLS) system installed at the Beijing Radioactive Ion-beam Facility (BRIF), aiming to investigate the nuclear properties of unstable nuclei. The first on-line commissioning experiment of this system was performed using the continuous stable ($^{39}$K) and unstable ($^{38}$K) ion beams produced by impinging a 100-MeV proton beam on a CaO target. Hy… ▽ More We have constructed a collinear laser spectroscopy (CLS) system installed at the Beijing Radioactive Ion-beam Facility (BRIF), aiming to investigate the nuclear properties of unstable nuclei. The first on-line commissioning experiment of this system was performed using the continuous stable ($^{39}$K) and unstable ($^{38}$K) ion beams produced by impinging a 100-MeV proton beam on a CaO target. Hyperfine structure spectra of these two isotopes are reasonably reproduced, and the extracted magnetic dipole hyperfine parameters and isotope shift agree with the literature values. The on-line experiment demonstrates the overall functioning of this CLS system, opening new opportunities for laser spectroscopy measurement of unstable isotopes at BRIF and other radioactive ion beam facilities in China. △ Less

Submitted 11 March, 2022; originally announced March 2022.

Studies of the Earth shielding effect to direct dark matter searches at the China Jinping Underground Laboratory

Authors: Z. Z. Liu, L. T. Yang, Q. Yue, C. H. Yeh, K. J. Kang, Y. J. Li, M. Agartioglu, H. P. An, J. P. Chang, J. H. Chen, Y. H. Chen, J. P. Cheng, W. H. Dai, Z. Deng, C. H. Fang, X. P. Geng, H. Gong, X. Y. Guo, Q. J. Guo, L. He, S. M. He, J. W. Hu, H. X. Huang, T. C. Huang, H. T. Jia , et al. (58 additional authors not shown)

Abstract: Dark matter direct detection experiments mostly operate at deep underground laboratories. It is necessary to consider shielding effect of the Earth, especially for dark matter particles interacting with a large cross section. We analyzed and simulated the Earth shielding effect for dark matter at the China Jinping Underground Laboratory (CJPL) with a simulation package, CJPL Earth Shielding Simula… ▽ More Dark matter direct detection experiments mostly operate at deep underground laboratories. It is necessary to consider shielding effect of the Earth, especially for dark matter particles interacting with a large cross section. We analyzed and simulated the Earth shielding effect for dark matter at the China Jinping Underground Laboratory (CJPL) with a simulation package, CJPL Earth Shielding Simulation code (CJPL\_ESS), which is applicable to other underground locations. The further constraints on the $χ$-N cross section exclusion regions are derived based on the studies with CDEX experiment data. △ Less

Submitted 9 March, 2022; v1 submitted 22 November, 2021; originally announced November 2021.

Comments: 8 pages, 8 figures, 2 tables. Version updated to match PRD version

Journal ref: Phys. Rev. D 105, 052005 (2022)

Property investigation for different wedge-shaped CsI(Tl)s

Authors: G. Li, J. L. Lou, Y. L. Ye, H. Hua, H. Wang, J. X. Han, W. Liu, S. W. Bai, Z. W. Tan, K. Ma, J. H. Chen, L. S. Yang, S. J. Wang, Z. Y. Hu, H. Z. Yu, H. Y. Zhu, B. L. Xia, Y. Jiang, Y. Liu, X. F. Yang, Q. T. Li, J. Y. Xu, J. S. Wang, Y. Y. Yang, J. B. Ma , et al. (10 additional authors not shown)

Abstract: Two types of wedge-shaped CsI(Tl)s were designed to be placed behind the annular double-sided silicon detectors (ADSSDs) to identify the light charged particles with the $ΔE-E$ method. The properties of CsI(Tl)s with different shapes and sizes, such as energy resolution, light output non-uniformity and particle identification capability, were compared by using a $α$-source and a radioactive beam o… ▽ More Two types of wedge-shaped CsI(Tl)s were designed to be placed behind the annular double-sided silicon detectors (ADSSDs) to identify the light charged particles with the $ΔE-E$ method. The properties of CsI(Tl)s with different shapes and sizes, such as energy resolution, light output non-uniformity and particle identification capability, were compared by using a $α$-source and a radioactive beam of $^{15}$C. The big-size CsI(Tl) was finally adopted to form the $ΔE-E$ telescope due to better properties. The property differences of these two types of CsI(Tl)s can be interpreted based on the Geant4 simulation results. △ Less

Submitted 2 March, 2021; originally announced March 2021.

First experimental constraints on WIMP couplings in the effective field theory framework from CDEX

Authors: Y. Wang, Z. Zeng, Q. Yue, L. T. Yang, K. J. Kang, Y. J. Li, M. Agartioglu, H. P. An, J. P. Chang, J. H. Chen, Y. H. Chen, J. P. Cheng, C. Y. Chiang, W. H. Dai, Z. Deng, C. H. Fang, X. P. Geng, H. Gong, Q. J. Guo, X. Y. Guo, H. J. He, L. He, S. M. He, J. W. Hu, T. C. Huang , et al. (63 additional authors not shown)

Abstract: We present weakly interacting massive particles (WIMPs) search results performed using two approaches of effective field theory from the China Dark Matter Experiment (CDEX), based on the data from both CDEX-1B and CDEX-10 stages. In the nonrelativistic effective field theory approach, both time-integrated and annual modulation analyses were used to set new limits for the coupling of WIMP-nucleon e… ▽ More We present weakly interacting massive particles (WIMPs) search results performed using two approaches of effective field theory from the China Dark Matter Experiment (CDEX), based on the data from both CDEX-1B and CDEX-10 stages. In the nonrelativistic effective field theory approach, both time-integrated and annual modulation analyses were used to set new limits for the coupling of WIMP-nucleon effective operators at 90% confidence level (C.L.) and improve over the current bounds in the low $m_χ$ region. In the chiral effective field theory approach, data from CDEX-10 were used to set an upper limit on WIMP-pion coupling at 90% C.L. We for the first time extended the limit to the $m_χ<$ 6 GeV/$c^2$ region. △ Less

Submitted 26 April, 2021; v1 submitted 30 July, 2020; originally announced July 2020.

Comments: version accepted by Science China-PMA, 8 pages, 8 figures

Journal ref: Sci. China-Phys. Mech. Astron. 64, 281011 (2021)

Development of the Soft X-ray AGM-AGS RIXS Beamline at Taiwan Photon Source

Authors: A. Singh, H. Y. Huang, Y. Y. Chu, C. Y. Hua, S. W. Lin, H. S. Fung, H. W. Shiu, J. Chang, J. H. Li, J. Okamoto, C. C. Chiu, C. H. Chang, W. B. Wu, S. Y. Perng, S. C. Chung, K. Y. Kao, S. C. Yeh, H. Y. Chao, J. H. Chen, D. J. Huang, C. T. Chen

Abstract: We report on the development of a high-resolution and highly efficient beamline for soft-X-ray resonant inelastic X-ray scattering (RIXS) located at Taiwan Photon Source. This beamline adopts an optical design that uses an active grating monochromator (AGM) and an active grating spectrometer (AGS) to implement the energy compensation principle of grating dispersion. Active gratings are utilized to… ▽ More We report on the development of a high-resolution and highly efficient beamline for soft-X-ray resonant inelastic X-ray scattering (RIXS) located at Taiwan Photon Source. This beamline adopts an optical design that uses an active grating monochromator (AGM) and an active grating spectrometer (AGS) to implement the energy compensation principle of grating dispersion. Active gratings are utilized to diminish defocus, coma and higher-order aberrations as well as to decrease the slope errors caused by thermal deformation and optical polishing. The AGS is mounted on a rotatable granite platform to enable momentum-resolved RIXS measurements with scattering angle over a wide range. Several high-precision instruments developed in house for this beamline are briefly described. The best energy resolution obtained from this AGM-AGS beamline was 12.4 meV at 530 eV, achieving a resolving power 42,000, while the bandwidth of the incident soft X-rays was kept at 0.5 eV. To demonstrate the scientific impacts of high-resolution RIXS, we present an example of momentum-resolved RIXS measurements on a high-temperature superconducting cuprate, La$_{2-x}$Sr$_x$CuO$_4$. The measurements reveal the A$_{1g}$ apical oxygen phonons in superconducting cuprates, opening a new opportunity to investigate the coupling between these phonons and charge density waves. △ Less

Submitted 24 June, 2020; v1 submitted 23 June, 2020; originally announced June 2020.

Comments: 9 pages, p figures, submitted to J. of Synchrotron Radiation. Revise expression

A scalable weakly-synchronous algorithm for solving partial differential equations

Authors: Konduri Aditya, Tobias Gysi, Grzegorz Kwasniewski, Torsten Hoefler, Diego A. Donzis, Jacqueline H. Chen

Abstract: Synchronization overheads pose a major challenge as applications advance towards extreme scales. In current large-scale algorithms, synchronization as well as data communication delay the parallel computations at each time step in a time-dependent partial differential equation (PDE) solver. This creates a new scaling wall when moving towards exascale. We present a weakly-synchronous algorithm base… ▽ More Synchronization overheads pose a major challenge as applications advance towards extreme scales. In current large-scale algorithms, synchronization as well as data communication delay the parallel computations at each time step in a time-dependent partial differential equation (PDE) solver. This creates a new scaling wall when moving towards exascale. We present a weakly-synchronous algorithm based on novel asynchrony-tolerant (AT) finite-difference schemes that relax synchronization at a mathematical level. We utilize remote memory access programming schemes that have been shown to provide significant speedup on modern supercomputers, to efficiently implement communications suitable for AT schemes, and compare to two-sided communications that are state-of-practice. We present results from simulations of Burgers' equation as a model of multi-scale strongly non-linear dynamical systems. Our algorithm demonstrate excellent scalability of the new AT schemes for large-scale computing, with a speedup of up to $3.3$x in communication time and $2.19$x in total runtime. We expect that such schemes can form the basis for exascale PDE algorithms. △ Less

Submitted 13 November, 2019; originally announced November 2019.

Improved limits on solar axions and bosonic dark matter from the CDEX-1B experiment using the profile likelihood ratio method

Authors: Y. Wang, Q. Yue, S. K. Liu, K. J. Kang, Y. J. Li, H. P. An, J. P. Chang, J. H. Chen, Y. H. Chen, J. P. Cheng, W. H. Dai, Z. Deng, X. P. Geng, H. Gong, P. Gu, X. Y. Guo, H. T. He, L. He, S. M. He, J. W. Hu, H. X. Huang, T. C. Huang, L. P. Jia, H. B. Li, H. Li , et al. (55 additional authors not shown)

Abstract: We present the improved constraints on couplings of solar axions and more generic bosonic dark matter particles using 737.1 kg-days of data from the CDEX-1B experiment. The CDEX-1B experiment, located at the China Jinping Underground Laboratory, primarily aims at the direct detection of weakly interacting massive particles using a p-type point-contact germanium detector. We adopt the profile likel… ▽ More We present the improved constraints on couplings of solar axions and more generic bosonic dark matter particles using 737.1 kg-days of data from the CDEX-1B experiment. The CDEX-1B experiment, located at the China Jinping Underground Laboratory, primarily aims at the direct detection of weakly interacting massive particles using a p-type point-contact germanium detector. We adopt the profile likelihood ratio method for analysis of data in the presence of backgrounds. An energy threshold of 160 eV was achieved, much better than the 475 eV of CDEX-1A with an exposure of 335.6 kg-days. This significantly improves the sensitivity for the bosonic dark matter below 0.8 keV among germanium detectors. Limits are also placed on the coupling $g_{Ae} < 2.48 \times 10^{-11}$ from Compton, bremsstrahlung, atomic-recombination and de-excitation channels and $g^{eff}_{AN} \times g_{Ae} < 4.14 \times 10^{-17}$ from a $^{57}$Fe M1 transition at 90\% confidence level. △ Less

Submitted 26 April, 2021; v1 submitted 8 November, 2019; originally announced November 2019.

Comments: version accepted by PRD, 9 pages, 11 figures

Journal ref: Phys. Rev. D 101, 052003 (2020)

Direct Detection Constraints on Dark Photons with CDEX-10 Experiment at the China Jinping Underground Laboratory

Authors: Z. She, L. P. Jia, Q. Yue, H. Ma, K. J. Kang, Y. J. Li, M. Agartioglu, H. P. An, J. P. Chang, J. H. Chen, Y. H. Chen, J. P. Cheng, W. H. Dai, Z. Deng, X. P. Geng, H. Gong, P. Gu, Q. J. Guo, X. Y. Guo, L. He, S. M. He, H. T. He, J. W. Hu, T. C. Huang, H. X. Huang , et al. (59 additional authors not shown)

Abstract: We report constraints on the dark photon effective kinetic mixing parameter ($κ$) with data taken from two ${p}$-type point-contact germanium detectors of the CDEX-10 experiment at the China Jinping Underground Laboratory. The 90\% confidence level upper limits on $κ$ of solar dark photon from 205.4 kg-day exposure are derived, probing new parameter space with masses (${m_V}$) from 10 to 300 eV/… ▽ More We report constraints on the dark photon effective kinetic mixing parameter ($κ$) with data taken from two ${p}$-type point-contact germanium detectors of the CDEX-10 experiment at the China Jinping Underground Laboratory. The 90\% confidence level upper limits on $κ$ of solar dark photon from 205.4 kg-day exposure are derived, probing new parameter space with masses (${m_V}$) from 10 to 300 eV/${c^2}$ in direct detection experiments. Considering dark photon as the cosmological dark matter, limits at 90\% confidence level with ${m_V}$ from 0.1 to 4.0 keV/${c^2}$ are set from 449.6 kg-day data, with a minimum of ${\rm{κ=1.3 \times 10^{-15}}}$ at ${\rm{m_V=200\ eV/c^2}}$. △ Less

Submitted 18 March, 2020; v1 submitted 29 October, 2019; originally announced October 2019.

Comments: 5 pages, 6 figures

Journal ref: Phys. Rev. Lett. 124, 111301 (2020)

Constraints on Spin-Independent Nucleus Scattering with sub-GeV Weakly Interacting Massive Particle Dark Matter from the CDEX-1B Experiment at the China Jin-Ping Laboratory

Authors: Z. Z. Liu, Q. Yue, L. T. Yang, K. J. Kang, Y. J. Li, H. T. Wong, M. Agartioglu, H. P. An, J. P. Chang, J. H. Chen, Y. H. Chen, J. P. Cheng, Z. Deng, Q. Du, H. Gong, X. Y. Guo, L. He, S. M. He, J. W. Hu, Q. D. Hu, H. X. Huang, L. P. Jia, H. Jiang, H. B. Li, H. Li , et al. (46 additional authors not shown)

Abstract: We report results on the searches of weakly interacting massive particles (WIMPs) with sub-GeV masses ($m_χ$) via WIMP-nucleus spin-independent scattering with Migdal effect incorporated. Analysis on time-integrated (TI) and annual modulation (AM) effects on CDEX-1B data are performed, with 737.1 kg$\cdot$day exposure and 160 eVee threshold for TI analysis, and 1107.5 kg$\cdot$day exposure and 250… ▽ More We report results on the searches of weakly interacting massive particles (WIMPs) with sub-GeV masses ($m_χ$) via WIMP-nucleus spin-independent scattering with Migdal effect incorporated. Analysis on time-integrated (TI) and annual modulation (AM) effects on CDEX-1B data are performed, with 737.1 kg$\cdot$day exposure and 160 eVee threshold for TI analysis, and 1107.5 kg$\cdot$day exposure and 250 eVee threshold for AM analysis. The sensitive windows in $m_χ$ are expanded by an order of magnitude to lower DM masses with Migdal effect incorporated. New limits on $σ_{χN}^{\rm SI}$ at 90\% confidence level are derived as $2\times$10$^{-32}\sim7\times$10$^{-35}$ $\rm cm^2$ for TI analysis at $m_χ\sim$ 50$-$180 MeV/$c^2$, and $3\times$10$^{-32}\sim9\times$10$^{-38}$ $\rm cm^2$ for AM analysis at $m_χ\sim$75 MeV/$c^2-$3.0 GeV/$c^2$. △ Less

Submitted 15 October, 2019; v1 submitted 1 May, 2019; originally announced May 2019.

Comments: 5 pages, 4 figures

Journal ref: Phys. Rev. Lett. 123, 161301 (2019)

Search for Light Weakly-Interacting-Massive-Particle Dark Matter by Annual Modulation Analysis with a Point-Contact Germanium Detector at the China Jinping Underground Laboratory

Authors: L. T. Yang, H. B. Li, Q. Yue, H. Ma, K. J. Kang, Y. J. Li, H. T. Wong, M. Agartioglu, H. P. An, J. P. Chang, J. H. Chen, Y. H. Chen, J. P. Cheng, Z. Deng, Q. Du, H. Gong, Q. J. Guo, L. He, J. W. Hu, Q. D. Hu, H. X. Huang, L. P. Jia, H. Jiang, H. Li, J. M. Li , et al. (50 additional authors not shown)

Abstract: We present results on light weakly interacting massive particle (WIMP) searches with annual modulation (AM) analysis on data from a 1-kg mass $p$-type point-contact germanium detector of the CDEX-1B experiment at the China Jinping Underground Laboratory. Datasets with a total live time of 3.2 yr within a 4.2 yr span are analyzed with analysis threshold of 250 eVee. Limits on WIMP-nucleus ($χ$-$N$)… ▽ More We present results on light weakly interacting massive particle (WIMP) searches with annual modulation (AM) analysis on data from a 1-kg mass $p$-type point-contact germanium detector of the CDEX-1B experiment at the China Jinping Underground Laboratory. Datasets with a total live time of 3.2 yr within a 4.2 yr span are analyzed with analysis threshold of 250 eVee. Limits on WIMP-nucleus ($χ$-$N$) spin-independent cross sections as function of WIMP mass ($m_χ$) at 90\% confidence level (C.L.) are derived using the dark matter halo model. Within the context of the standard halo model, the 90\% C.L. allowed regions implied by the DAMA/LIBRA and CoGeNT AM-based analysis are excluded at $>$99.99\% and 98\% C.L., respectively. These results correspond to the best sensitivity at $m_χ$$<$6$~{\rm GeV}/c^2$ among WIMP AM measurements to date. △ Less

Submitted 25 November, 2019; v1 submitted 29 April, 2019; originally announced April 2019.

Comments: 5 pages, 4 figures

Journal ref: Phys. Rev. Lett. 123, 221301 (2019)

Performances of a prototype point-contact germanium detector immersed in liquid nitrogen for light dark matter search

Authors: H. Jiang, L. T. Yang, Q. Yue, K. J. Kang, J. P. Cheng, Y. J. Li, H. T. Wong, M. Agartioglu, H. P. An, J. P. Chang, J. H. Chen, Y. H. Chen, Z. Deng, Q. Du, H. Gong, L. He, J. W. Hu, Q. D. Hu, H. X. Huang, L. P. Jia, H. B. Li, H. Li, J. M. Li, J. Li, X. Li , et al. (48 additional authors not shown)

Abstract: The CDEX-10 experiment searches for light weakly-interacting massive particles, a form of dark matter, at the China JinPing underground laboratory, where approximately 10 kg of germanium detectors are arranged in an array and immersed in liquid nitrogen. Herein, we report on the experimental apparatus, detector characterization, and spectrum analysis of one prototype detector. Owing to the higher… ▽ More The CDEX-10 experiment searches for light weakly-interacting massive particles, a form of dark matter, at the China JinPing underground laboratory, where approximately 10 kg of germanium detectors are arranged in an array and immersed in liquid nitrogen. Herein, we report on the experimental apparatus, detector characterization, and spectrum analysis of one prototype detector. Owing to the higher rise-time resolution of the CDEX-10 prototype detector as compared with CDEX-1B, we identified the origin of an observed category of extremely fast events. For data analysis of the CDEX-10 prototype, we introduced and applied an improved bulk/surface event discrimination method. The results of the new method were compared to those of the CDEX-1B spectrum. Both sets of results showed good consistency in the 0--12 keVee energy range, except for the 8.0 keV K-shell X-ray peak from the external copper. △ Less

Submitted 20 October, 2018; originally announced October 2018.

Comments: version accepted by SCPMA, 8 pages, 11 figures and 2 tables

Journal ref: Sci. China Phys. Mech. Astron. 62, 031012 (2019)

Limits on Light Weakly Interacting Massive Particles from the First 102.8 kg ${\times}$ day Data of the CDEX-10 Experiment

Authors: H. Jiang, L. P. Jia, Q. Yue, K. J. Kang, J. P. Cheng, Y. J. Li, H. T. Wong, M. Agartioglu, H. P. An, J. P. Chang, J. H. Chen, Y. H. Chen, Z. Deng, Q. Du, H. Gong, L. He, J. W. Hu, Q. D. Hu, H. X. Huang, H. B. Li, H. Li, J. M. Li, J. Li, X. Li, X. Q. Li , et al. (48 additional authors not shown)

Abstract: We report the first results of a light weakly interacting massive particles (WIMPs) search from the CDEX-10 experiment with a 10 kg germanium detector array immersed in liquid nitrogen at the China Jinping Underground Laboratory with a physics data size of 102.8 kg day. At an analysis threshold of 160 eVee, improved limits of 8 $\times 10^{-42}$ and 3 $\times 10^{-36}$ cm$^{2}$ at a 90\% confidenc… ▽ More We report the first results of a light weakly interacting massive particles (WIMPs) search from the CDEX-10 experiment with a 10 kg germanium detector array immersed in liquid nitrogen at the China Jinping Underground Laboratory with a physics data size of 102.8 kg day. At an analysis threshold of 160 eVee, improved limits of 8 $\times 10^{-42}$ and 3 $\times 10^{-36}$ cm$^{2}$ at a 90\% confidence level on spin-independent and spin-dependent WIMP-nucleon cross sections, respectively, at a WIMP mass ($m_χ$) of 5 GeV/${c}^2$ are achieved. The lower reach of $m_χ$ is extended to 2 GeV/${c}^2$. △ Less

Submitted 26 June, 2018; v1 submitted 25 February, 2018; originally announced February 2018.

Comments: 5 pages, 4 figures

Journal ref: Phys. Rev. Lett. 120, 241301 (2018)

Limits on light WIMPs with a 1 kg-scale germanium detector at 160 eVee physics threshold at the China Jinping Underground Laboratory

Authors: L. T. Yang, H. B. Li, Q. Yue, K. J. Kang, J. P. Cheng, Y. J. Li, H. T. Wong, M. Aǧartioǧlu, H. P. An, J. P. Chang, J. H. Chen, Y. H. Chen, Z. Deng, Q. Du, H. Gong, L. He, J. W. Hu, Q. D. Hu, H. X. Huang, L. P. Jia, H. Jiang, H. Li, J. M. Li, J. Li, X. Li , et al. (43 additional authors not shown)

Abstract: We report results of a search for light weakly interacting massive particle (WIMP) dark matter from the CDEX-1 experiment at the China Jinping Underground Laboratory (CJPL). Constraints on WIMP-nucleon spin-independent (SI) and spin-dependent (SD) couplings are derived with a physics threshold of 160 eVee, from an exposure of 737.1 kg-days. The SI and SD limits extend the lower reach of light WIMP… ▽ More We report results of a search for light weakly interacting massive particle (WIMP) dark matter from the CDEX-1 experiment at the China Jinping Underground Laboratory (CJPL). Constraints on WIMP-nucleon spin-independent (SI) and spin-dependent (SD) couplings are derived with a physics threshold of 160 eVee, from an exposure of 737.1 kg-days. The SI and SD limits extend the lower reach of light WIMPs to 2 GeV and improve over our earlier bounds at WIMP mass less than 6 GeV. △ Less

Submitted 26 June, 2018; v1 submitted 18 October, 2017; originally announced October 2017.

Comments: 10 pages, 10 figures

Journal ref: Chin. Phys. C 42, 23002 (2018)

Bulk and Surface Event Identification in p-type Germanium Detectors

Authors: L. T. Yang, H. B. Li, H. T. Wong, M. Agartioglu, J. H. Chen, L. P. Jia, H. Jiang, J. Li, F. K. Lin, S. T. Lin, S. K. Liu, J. L. Ma, B. Sevda, V. Sharma, L. Singh, M. K. Singh, M. K. Singh, A. K. Soma, A. Sonay, S. W. Yang, L. Wang, Q. Wang, Q. Yue, W. Zhao

Abstract: The p-type point-contact germanium detectors have been adopted for light dark matter WIMP searches and the studies of low energy neutrino physics. These detectors exhibit anomalous behavior to events located at the surface layer. The previous spectral shape method to identify these surface events from the bulk signals relies on spectral shape assumptions and the use of external calibration sources… ▽ More The p-type point-contact germanium detectors have been adopted for light dark matter WIMP searches and the studies of low energy neutrino physics. These detectors exhibit anomalous behavior to events located at the surface layer. The previous spectral shape method to identify these surface events from the bulk signals relies on spectral shape assumptions and the use of external calibration sources. We report an improved method in separating them by taking the ratios among different categories of in situ event samples as calibration sources. Data from CDEX-1 and TEXONO experiments are re-examined using the ratio method. Results are shown to be consistent with the spectral shape method. △ Less

Submitted 8 January, 2018; v1 submitted 10 November, 2016; originally announced November 2016.

Comments: 29 pages, 16 figures

Journal ref: Nucl. Instr. Meth. Phys. Res. A 886 (2018) 13-23

Constraints on Axion couplings from the CDEX-1 experiment at the China Jinping Underground Laboratory

Authors: S. K. Liu, Q. Yue, K. J. Kang, J. P. Cheng, H. T. Wong, Y. J. Li, H. B. Li, S. T. Lin, J. P. Chang, J. H. Chen, N. Chen, Q. H. Chen, Y. H. Chen, Z. Deng, Q. Du, H. Gong, H. J. He, Q. J. He, H. X. Huang, H. Jiang, J. M. Li, J. Li, J. Li, X. Li, X. Q. Li , et al. (49 additional authors not shown)

Abstract: We report the results of searches for solar axions and galactic dark matter axions or axion-like particles with CDEX-1 experiment at the China Jinping Underground Laboratory, using 335.6 kg-days of data from a p-type point-contact germanium detector. The data are compatible with the background model and no excess signals are observed. Limits of solar axions on the model independent coupling… ▽ More We report the results of searches for solar axions and galactic dark matter axions or axion-like particles with CDEX-1 experiment at the China Jinping Underground Laboratory, using 335.6 kg-days of data from a p-type point-contact germanium detector. The data are compatible with the background model and no excess signals are observed. Limits of solar axions on the model independent coupling $g_{Ae}<2.5\times10^{-11}$ from Compton, bremsstrahlung, atomic-recombination and deexcitation channel and $g^{\text{eff}}_{AN}\times g_{Ae}<6.1\times10^{-17}$ from $^{57}$Fe M1 transition at 90 % confidence level are derived. Within the framework of the DFSZ and KSVZ models, our results exclude the axion mass heavier than 0.9 eV/c$^{2}$ and 173 eV/c$^{2}$, respectively. The derived constraints for dark matter axions below 1 keV improves over the previous results. △ Less

Submitted 24 October, 2016; originally announced October 2016.

Comments: 8 pages, 8 figures

Journal ref: Phys. Rev. D 95, 052006 (2017)

A Search of Low-Mass WIMPs with p-type Point Contact Germanium Detector in the CDEX-1 Experiment

Authors: W. Zhao, Q. Yue, K. J. Kang, J. P. Cheng, Y. J. Li, H. T. Wong, S. T. Lin, J. P. Chang, J. H. Chen, Q. H. Chen, Y. H. Chen, Z. Deng, Q. Du, H. Gong, X. Q. Hao, H. J. He, Q. J. He, H. X. Huang, T. R. Huang, H. Jiang, H. B. Li, J. Li, J. Li, J. M. Li, X. Li , et al. (48 additional authors not shown)

Abstract: The CDEX-1 experiment conducted a search of low-mass (< 10 GeV/c2) Weakly Interacting Massive Particles (WIMPs) dark matter at the China Jinping Underground Laboratory using a p-type point-contact germanium detector with a fiducial mass of 915 g at a physics analysis threshold of 475 eVee. We report the hardware set-up, detector characterization, data acquisition and analysis procedures of this ex… ▽ More The CDEX-1 experiment conducted a search of low-mass (< 10 GeV/c2) Weakly Interacting Massive Particles (WIMPs) dark matter at the China Jinping Underground Laboratory using a p-type point-contact germanium detector with a fiducial mass of 915 g at a physics analysis threshold of 475 eVee. We report the hardware set-up, detector characterization, data acquisition and analysis procedures of this experiment. No excess of unidentified events are observed after subtraction of known background. Using 335.6 kg-days of data, exclusion constraints on the WIMP-nucleon spin-independent and spin-dependent couplings are derived. △ Less

Submitted 18 January, 2016; originally announced January 2016.

Comments: 12 pages, 19 figures

Journal ref: Phys. Rev. D 93, 092003 (2016)

Characterization and Performance of Germanium Detectors with sub-keV Sensitivities for Neutrino and Dark Matter Experiments

Authors: The TEXONO Collaboration, A. K. Soma, M. K. Singh, L. Singh, G. Kiran Kumar, F. K. Lin, Q. Du, H. Jiang, S. K. Liu, J. L. Ma, V. Sharma, L. Wang, Y. C. Wu, L. T. Yang, W. Zhao, M. Agartioglu, G. Asryan, Y. Y. Chang, J. H. Chen, Y. C. Chuang, M. Deniz, C. L. Hsu, Y. H. Hsu, T. R. Huang, L. P. Jia , et al. (24 additional authors not shown)

Abstract: Germanium ionization detectors with sensitivities as low as 100 eVee (electron-equivalent energy) open new windows for studies on neutrino and dark matter physics. The relevant physics subjects are summarized. The detectors have to measure physics signals whose amplitude is comparable to that of pedestal electronic noise. To fully exploit this new detector technique, various experimental issues in… ▽ More Germanium ionization detectors with sensitivities as low as 100 eVee (electron-equivalent energy) open new windows for studies on neutrino and dark matter physics. The relevant physics subjects are summarized. The detectors have to measure physics signals whose amplitude is comparable to that of pedestal electronic noise. To fully exploit this new detector technique, various experimental issues including quenching factors, energy reconstruction and calibration, signal triggering and selection as well as evaluation of their associated efficiencies have to be attended. The efforts and results of a research program to address these challenges are presented. △ Less

Submitted 1 September, 2016; v1 submitted 18 November, 2014; originally announced November 2014.

Comments: 18 pages, 18 figures, 3 table; v3 -- Published Version

Journal ref: Nuclear Instruments and Methods A 836, 67-82 (2016)

Phenomenological study of light (anti)nuclei, (anti)hypertriton and di-Lambda production at RHIC

Authors: L. Xue, Y. G. Ma, J. H. Chen, S. Zhang

Abstract: We present the production of light (anti)nuclei, (anti)hypertriton and di-Lambda based on coalescence model in central Au+Au collisions at $\sqrt{s_{NN}}=200GeV$. The invariant yields of \He(\Hebar), \hypert(\hypertbar), \Hee(\Heebar) obtained is found to be consistent with the STAR measurements. The $p_{T}$ integrated yields for di-Lambda $dN_{ΛΛ}/dy \sim 2.23\times10^{-5}$, and is not strongly d… ▽ More We present the production of light (anti)nuclei, (anti)hypertriton and di-Lambda based on coalescence model in central Au+Au collisions at $\sqrt{s_{NN}}=200GeV$. The invariant yields of \He(\Hebar), \hypert(\hypertbar), \Hee(\Heebar) obtained is found to be consistent with the STAR measurements. The $p_{T}$ integrated yields for di-Lambda $dN_{ΛΛ}/dy \sim 2.23\times10^{-5}$, and is not strongly dependent on the parameter employed for coalescence process. Relative particle ratios of light anti(nuclei) and (anti)hypertriton are explored, and agree with experimental data and thermal model predictions quite well. An exponential reducion behavior is presented for the differential invariant yields with increased baryon number. The production rate reduces by a factor of 1692 (1285) for each additional antinucleon (nucleon) added to antinuclei (nuclei), and the production rate of \Libar is predicted to be $10^{-16}$ which is consistent with STAR result. △ Less

Submitted 6 November, 2012; v1 submitted 21 June, 2012; originally announced June 2012.

Comments: 4 pages, 3 figures parallel talk delivered by L. Xue at the 14th national conference on nuclear structure, April 12nd - 16th, 2012, Huzhou, China

Journal ref: Phys.Rev.C 85 (2012) 064912