Showing 1–8 of 8 results for author: Chen, Y M

Pressure induced Structure Change and Anomalies in Thermodynamic Quantities and Transport Properties in Liquid Lithium Hydride

Authors: X. Z. Yan, Y. M. Chen, Hua Y. Geng, Y. F. Wang, Y. Sun, L. L. Zhang, H. Wang, Y. L. Xu

Abstract: Understand the nature of liquid structure and its evolution under different conditions is a major challenge in condensed physics and materials science. Here, we report a pressure-induced structure change spanning a wide pressure range in liquid-state lithium hydride (LiH) by first-principles molecular dynamic simulations. This behavior can be described as a continuous crossover from low pressure l… ▽ More Understand the nature of liquid structure and its evolution under different conditions is a major challenge in condensed physics and materials science. Here, we report a pressure-induced structure change spanning a wide pressure range in liquid-state lithium hydride (LiH) by first-principles molecular dynamic simulations. This behavior can be described as a continuous crossover from low pressure liquid with Li$^+$-H$^-$ duality symmetry to high pressure one with broken of duality symmetry. The thermodynamic quantities such as heat capacity and ionic transport properties such as diffusivity are also saliently impacted. It is important to stress that such behavior is firstly predicted for this category of materials, which is ubiquitous in universe as well as in industry applications. Lastly, a comprehensive high-pressure high-temperature phase diagram of LiH is constructed, which embodies rich physics in this previously-thought-simple ionic compound. △ Less

Submitted 26 January, 2025; originally announced January 2025.

Comments: 23 pages, 4 figures, with Supplementary Information

Journal ref: Phys. Rev. B 111, 024102 (2025)

Performance of the CMS High Granularity Calorimeter prototype to charged pion beams of 20$-$300 GeV/c

Authors: B. Acar, G. Adamov, C. Adloff, S. Afanasiev, N. Akchurin, B. Akgün, M. Alhusseini, J. Alison, J. P. Figueiredo de sa Sousa de Almeida, P. G. Dias de Almeida, A. Alpana, M. Alyari, I. Andreev, U. Aras, P. Aspell, I. O. Atakisi, O. Bach, A. Baden, G. Bakas, A. Bakshi, S. Banerjee, P. DeBarbaro, P. Bargassa, D. Barney, F. Beaudette , et al. (435 additional authors not shown)

Abstract: The upgrade of the CMS experiment for the high luminosity operation of the LHC comprises the replacement of the current endcap calorimeter by a high granularity sampling calorimeter (HGCAL). The electromagnetic section of the HGCAL is based on silicon sensors interspersed between lead and copper (or copper tungsten) absorbers. The hadronic section uses layers of stainless steel as an absorbing med… ▽ More The upgrade of the CMS experiment for the high luminosity operation of the LHC comprises the replacement of the current endcap calorimeter by a high granularity sampling calorimeter (HGCAL). The electromagnetic section of the HGCAL is based on silicon sensors interspersed between lead and copper (or copper tungsten) absorbers. The hadronic section uses layers of stainless steel as an absorbing medium and silicon sensors as an active medium in the regions of high radiation exposure, and scintillator tiles directly readout by silicon photomultipliers in the remaining regions. As part of the development of the detector and its readout electronic components, a section of a silicon-based HGCAL prototype detector along with a section of the CALICE AHCAL prototype was exposed to muons, electrons and charged pions in beam test experiments at the H2 beamline at the CERN SPS in October 2018. The AHCAL uses the same technology as foreseen for the HGCAL but with much finer longitudinal segmentation. The performance of the calorimeters in terms of energy response and resolution, longitudinal and transverse shower profiles is studied using negatively charged pions, and is compared to GEANT4 predictions. This is the first report summarizing results of hadronic showers measured by the HGCAL prototype using beam test data. △ Less

Submitted 27 May, 2023; v1 submitted 9 November, 2022; originally announced November 2022.

Comments: Accepted for publication by JINST

Response of a CMS HGCAL silicon-pad electromagnetic calorimeter prototype to 20-300 GeV positrons

Authors: B. Acar, G. Adamov, C. Adloff, S. Afanasiev, N. Akchurin, B. Akgün, F. Alam Khan, M. Alhusseini, J. Alison, A. Alpana, G. Altopp, M. Alyari, S. An, S. Anagul, I. Andreev, P. Aspell, I. O. Atakisi, O. Bach, A. Baden, G. Bakas, A. Bakshi, S. Bannerjee, P. Bargassa, D. Barney, F. Beaudette , et al. (364 additional authors not shown)

Abstract: The Compact Muon Solenoid Collaboration is designing a new high-granularity endcap calorimeter, HGCAL, to be installed later this decade. As part of this development work, a prototype system was built, with an electromagnetic section consisting of 14 double-sided structures, providing 28 sampling layers. Each sampling layer has an hexagonal module, where a multipad large-area silicon sensor is glu… ▽ More The Compact Muon Solenoid Collaboration is designing a new high-granularity endcap calorimeter, HGCAL, to be installed later this decade. As part of this development work, a prototype system was built, with an electromagnetic section consisting of 14 double-sided structures, providing 28 sampling layers. Each sampling layer has an hexagonal module, where a multipad large-area silicon sensor is glued between an electronics circuit board and a metal baseplate. The sensor pads of approximately 1 cm$^2$ are wire-bonded to the circuit board and are readout by custom integrated circuits. The prototype was extensively tested with beams at CERN's Super Proton Synchrotron in 2018. Based on the data collected with beams of positrons, with energies ranging from 20 to 300 GeV, measurements of the energy resolution and linearity, the position and angular resolutions, and the shower shapes are presented and compared to a detailed Geant4 simulation. △ Less

Submitted 31 March, 2022; v1 submitted 12 November, 2021; originally announced November 2021.

Test Beam Study of SiPM-on-Tile Configurations

Authors: A. Belloni, Y. M. Chen, A. Dyshkant, T. K. Edberg, S. Eno, V. Zutshi, J. Freeman, M. Krohn, Y. Lai, D. Lincoln, S. Los, J. Mans, G. Reichenbach, L. Uplegger, S. A. Uzunyan

Abstract: Light yield and spatial uniformity for a large variety of configurations of scintillator tiles was studied. The light from each scintillator was collected by a Silicon Photomultiplier (SiPM) directly viewing the produced scintillation light (SiPM-on-tile technique). The varied parameters included tile transverse size, tile thickness, tile wrapping material, scintillator composition, and SiPM model… ▽ More Light yield and spatial uniformity for a large variety of configurations of scintillator tiles was studied. The light from each scintillator was collected by a Silicon Photomultiplier (SiPM) directly viewing the produced scintillation light (SiPM-on-tile technique). The varied parameters included tile transverse size, tile thickness, tile wrapping material, scintillator composition, and SiPM model. These studies were performed using 120 GeV protons at the Fermilab Test Beam Facility. External tracking allowed the position of each proton penetrating a tile to be measured. The results were compared to a GEANT4 simulation of each configuration of scinitillator, wrapping, and SiPM. △ Less

Submitted 17 May, 2021; v1 submitted 16 February, 2021; originally announced February 2021.

Comments: 19 pages, 15 figures, submitted to JINST

Construction and commissioning of CMS CE prototype silicon modules

Authors: B. Acar, G. Adamov, C. Adloff, S. Afanasiev, N. Akchurin, B. Akgün, M. Alhusseini, J. Alison, G. Altopp, M. Alyari, S. An, S. Anagul, I. Andreev, M. Andrews, P. Aspell, I. A. Atakisi, O. Bach, A. Baden, G. Bakas, A. Bakshi, P. Bargassa, D. Barney, E. Becheva, P. Behera, A. Belloni , et al. (307 additional authors not shown)

Abstract: As part of its HL-LHC upgrade program, the CMS Collaboration is developing a High Granularity Calorimeter (CE) to replace the existing endcap calorimeters. The CE is a sampling calorimeter with unprecedented transverse and longitudinal readout for both electromagnetic (CE-E) and hadronic (CE-H) compartments. The calorimeter will be built with $\sim$30,000 hexagonal silicon modules. Prototype modul… ▽ More As part of its HL-LHC upgrade program, the CMS Collaboration is developing a High Granularity Calorimeter (CE) to replace the existing endcap calorimeters. The CE is a sampling calorimeter with unprecedented transverse and longitudinal readout for both electromagnetic (CE-E) and hadronic (CE-H) compartments. The calorimeter will be built with $\sim$30,000 hexagonal silicon modules. Prototype modules have been constructed with 6-inch hexagonal silicon sensors with cell areas of 1.1~$cm^2$, and the SKIROC2-CMS readout ASIC. Beam tests of different sampling configurations were conducted with the prototype modules at DESY and CERN in 2017 and 2018. This paper describes the construction and commissioning of the CE calorimeter prototype, the silicon modules used in the construction, their basic performance, and the methods used for their calibration. △ Less

Submitted 10 December, 2020; originally announced December 2020.

Comments: 35 pages, submitted to JINST

The DAQ system of the 12,000 Channel CMS High Granularity Calorimeter Prototype

Authors: B. Acar, G. Adamov, C. Adloff, S. Afanasiev, N. Akchurin, B. Akgün, M. Alhusseini, J. Alison, G. Altopp, M. Alyari, S. An, S. Anagul, I. Andreev, M. Andrews, P. Aspell, I. A. Atakisi, O. Bach, A. Baden, G. Bakas, A. Bakshi, P. Bargassa, D. Barney, E. Becheva, P. Behera, A. Belloni , et al. (307 additional authors not shown)

Abstract: The CMS experiment at the CERN LHC will be upgraded to accommodate the 5-fold increase in the instantaneous luminosity expected at the High-Luminosity LHC (HL-LHC). Concomitant with this increase will be an increase in the number of interactions in each bunch crossing and a significant increase in the total ionising dose and fluence. One part of this upgrade is the replacement of the current endca… ▽ More The CMS experiment at the CERN LHC will be upgraded to accommodate the 5-fold increase in the instantaneous luminosity expected at the High-Luminosity LHC (HL-LHC). Concomitant with this increase will be an increase in the number of interactions in each bunch crossing and a significant increase in the total ionising dose and fluence. One part of this upgrade is the replacement of the current endcap calorimeters with a high granularity sampling calorimeter equipped with silicon sensors, designed to manage the high collision rates. As part of the development of this calorimeter, a series of beam tests have been conducted with different sampling configurations using prototype segmented silicon detectors. In the most recent of these tests, conducted in late 2018 at the CERN SPS, the performance of a prototype calorimeter equipped with ${\approx}12,000\rm{~channels}$ of silicon sensors was studied with beams of high-energy electrons, pions and muons. This paper describes the custom-built scalable data acquisition system that was built with readily available FPGA mezzanines and low-cost Raspberry PI computers. △ Less

Submitted 8 December, 2020; v1 submitted 7 December, 2020; originally announced December 2020.

Prediction of the Reactivity of Argon with Xenon under High Pressure

Authors: Xiao Z. Yan, Yang M. Chen, Hua Y. Geng

Abstract: Pressure significantly modifies the microscopic interactions in condense phase, leading to new patterns of bonding and unconventional chemistry. Both argon and xenon possess closed-shell electronic structures, which renders them chemically unreactive. Using unbiased structure searching techniques combined with first-principles calculations, we demonstrate the reaction of argon with xenon at a pres… ▽ More Pressure significantly modifies the microscopic interactions in condense phase, leading to new patterns of bonding and unconventional chemistry. Both argon and xenon possess closed-shell electronic structures, which renders them chemically unreactive. Using unbiased structure searching techniques combined with first-principles calculations, we demonstrate the reaction of argon with xenon at a pressure as low as 1.1 GPa, producing a novel van der Waals compound XeAr2, which crystallizes in the MgCu2-type Laves phase structure. Due to the pressure-induced delocalization of the electrons in outermost shells, the covalent Xe-Xe and Xe-Ar bonds have been detected which lead XeAr2 to be unexpectedly stable without any phase transition or decomposition at least up to 500 GPa. △ Less

Submitted 14 March, 2020; originally announced March 2020.

Comments: 11 pages, 5 figures

Journal ref: ACS Omega 4, 13640 (2019)

Compression and phase diagram of lithium hydrides at elevated pressures and temperatures by first-principles calculations

Authors: Yang M. Chen, Xiang R. Chen, Qiang Wu, Hua Y. Geng, Xiao Z. Yan, Yi X. Wang, Zi W. Wang

Abstract: High pressure and high temperature properties of AB (A = $^6$Li, $^7$Li; B = H, D, T) are investigated with first-principles method comprehensively. It is found that the H$^{-}$ sublattice features in the low-pressure electronic structure near the Fermi level of LiH are shifted to that dominated by the Li$^{+}$ sublattice in compression. The lattice dynamics is studied in quasi-harmonic approximat… ▽ More High pressure and high temperature properties of AB (A = $^6$Li, $^7$Li; B = H, D, T) are investigated with first-principles method comprehensively. It is found that the H$^{-}$ sublattice features in the low-pressure electronic structure near the Fermi level of LiH are shifted to that dominated by the Li$^{+}$ sublattice in compression. The lattice dynamics is studied in quasi-harmonic approximation, from which the phonon contribution to the free energy and the isotopic effects are accurately modelled with the aid of a parameterized double-Debye model. The obtained equation of state (EOS) matches perfectly with available static experimental data. The calculated principal Hugoniot is also in accordance with that derived from shock wave experiments. Using the calculated principal Hugoniot and the previous theoretical melting curve, we predict a shock melting point at 56 GPa and 1923 K. In order to establish the phase diagram for LiH, the phase boundaries between the B1 and B2 solid phases are explored. The B1-B2-liquid triple point is determined at about 241 GPa and 2413 K. The remarkable shift in the phase boundaries by isotopic effect and temperature reveal the significant role played by lattice vibrations. Furthermore, the Hugoniot of the static-dynamic coupling compression is assessed. Our EOS suggests that a precompression of the sample to 50 GPa will allow the shock Hugoniot passing through the triple point and entering the B2 solid phase. This transition leads to a discontinuity with 4.6% volume collapse, about four times greater than the same B1-B2 transition at zero temperature. △ Less

Submitted 7 July, 2016; originally announced July 2016.

Comments: 25 pages, 9 figures

MSC Class: 82D20

Journal ref: Journal of Physics D: Applied Physics 49 (2016) 355305 (10pp)