Showing 1–29 of 29 results for author: Qiao, R

Beam Test Characterization of Silicon Microstrip Detector Flight-Model Ladders for the AMS-02 Upgrade

Authors: Dexing Miao, Giovanni Ambrosi, Mattia Barbanera, Baasansuren Batsukh, Hengyi Cai, Mengke Cai, Xudong Cai, Yuman Cai, Yuan-Hann Chang, Shanzhen Chen, Hsin-Yi Chou, Xingzhu Cui, Mingyi Dong, Matteo Duranti, Ke Gong, Mingjie Feng, Valerio Formato, Yisheng Fu, Daojin Hong, Maria Ionica, Xiaojie Jiang, Yaozu Jiang, Liangchenglong Jin, Shengjie Jin, Vladimir Koutsenko , et al. (34 additional authors not shown)

Abstract: The AMS-02 experiment plans to install a new silicon microstrip tracker layer (Layer-0) on top of the existing detector, increasing the cosmic-ray acceptance by a factor of 3. Layer-0 employs a design in which multiple silicon microstrip detectors (SSDs) are connected in series to form long detector ladders. We present a detailed performance study of the flight-model ladders using a 350~GeV mixed… ▽ More The AMS-02 experiment plans to install a new silicon microstrip tracker layer (Layer-0) on top of the existing detector, increasing the cosmic-ray acceptance by a factor of 3. Layer-0 employs a design in which multiple silicon microstrip detectors (SSDs) are connected in series to form long detector ladders. We present a detailed performance study of the flight-model ladders using a 350~GeV mixed hadron beam at the CERN SPS. The study focuses on the following aspects: (i) the performance of ladders with different numbers of SSDs, for which the intrinsic spatial resolution at normal incidence varies from $9.5~μ\mathrm{m}$ to $11.4~μ\mathrm{m}$ for ladders composed of 8 to 12 SSDs; (ii) the response consistency for particles impacting on the \emph{Head} and \emph{Tail} regions of the ladder; and (iii) the dependence of the detector performance on the particle incidence angle. △ Less

Submitted 26 March, 2026; originally announced March 2026.

A Telescope System for Charge and Position Measurement of High Energy Nuclei

Authors: Dexing Miao, Zhiyu Xiang, Giovanni Ambrosi, Mattia Barbanera, Baasansuren Batsukh, Mengke Cai, Xudong Cai, Yuan-Hann Chang, Shanzhen Chen, Hsin-Yi Chou, Xingzhu Cui, Mingyi Dong, Matteo Duranti, Ke Gong, Mingjie Feng, Valerio Formato, Daojin Hong, Maria Ionica, Xiaojie Jiang, Yaozu Jiang, Liangchenglong Jin, Shengjie Jin, Vladimir Koutsenko, Tiange Li, Zuhao Li , et al. (21 additional authors not shown)

Abstract: A high-granularity telescope system with a large sensitive area and low material budget has been developed for high-energy heavy ion beam tests. The telescope consists of nine layers of silicon microstrip detectors (SSDs), whose performance was validated through a heavy ion beam test at the CERN SPS. A hybrid machine learning algorithm is proposed to address the challenges of nuclear charge measur… ▽ More A high-granularity telescope system with a large sensitive area and low material budget has been developed for high-energy heavy ion beam tests. The telescope consists of nine layers of silicon microstrip detectors (SSDs), whose performance was validated through a heavy ion beam test at the CERN SPS. A hybrid machine learning algorithm is proposed to address the challenges of nuclear charge measurement with SSDs. The system achieves a spatial resolution of $\mathcal{O}(1) \,$\SI{}{\micro\metre} and a charge resolution better than 0.16 charge units for nuclei from $Z = 1$ to $Z = 29$, with a sensitive area of $8 \times 8 \, \mathrm{cm}^2$. To the best of our knowledge, this represents the most precise charge and spatial resolution simultaneously achieved by a silicon telescope to date. △ Less

Submitted 26 March, 2026; originally announced March 2026.

A Silicon Microstrip Detector for Power-Limited and Large Sensitive Area Applications

Authors: Dexing Miao, Zijun Xu, Zhiyu Xiang, Pingcheng Liu, Giovanni Ambrosi, Mattia Barbanera, Mengke Cai, Xudong Cai, Hsin-Yi Chou, Matteo Duranti, Valerio Formato, Maria Ionica, Yaozu Jiang, Liangchenglong Jin, Vladimir Koutsenko, Qinze Li, Cong Liu, Xingjian Lv, Alberto Oliva, Wenxi Peng, Rui Qiao, Gianluigi Silvestre, Zibing Wu, Xuhao Yuan, Hongyu Zhang , et al. (2 additional authors not shown)

Abstract: A silicon microstrip detector (SSD) has been developed to have state of the art spatial resolution and a large sensitive area under stringent power constraints. The design incorporates three floating strips with their bias resistors inserted between two aluminum readout strips. Beam test measurements with the single sensor confirmed that this configuration achieves a total detection efficiency of… ▽ More A silicon microstrip detector (SSD) has been developed to have state of the art spatial resolution and a large sensitive area under stringent power constraints. The design incorporates three floating strips with their bias resistors inserted between two aluminum readout strips. Beam test measurements with the single sensor confirmed that this configuration achieves a total detection efficiency of $99.8 \, \%$ and spatial resolution $7.6 \, \mathrm{μm}$ for MIPs. A double-$η$ algorithm was developed to optimize hit position reconstruction for this SSD. The design can be adapted for large area silicon detectors. △ Less

Submitted 28 May, 2025; originally announced May 2025.

Comments: 9 pages, 13 figures

GECAM Discovery of Peculiar Oscillating Particle Precipitation Events

Authors: Chenwei Wang, Shaolin Xiong, Yi Zhao, Wei Xu, Gaopeng Lu, Xuzhi Zhou, Xiaocheng Guo, Wenya Li, Xiaochao Yang, Qinghe Zhang, Xinqiao Li, Zhenxia Zhang, Zhenghua An, Ce Cai, Peiyi Feng, Yue Huang, Min Gao, Ke Gong, Dongya Guo, Haoxuan Guo, Bing Li, Xiaobo Li, Yaqing Liu, Jiacong Liu, Xiaojing Liu , et al. (30 additional authors not shown)

Abstract: Charged particle precipitation typically manifests as a gradual increase and decrease of flux observed by space detectors. Cases with rapidly flux variation are very rare. Periodic events are even more extraordinary. These oscillating particle precipitation (OPP) events are usually attributed to the bounce motion of electrons, which are induced by lightning. Owing to the observation limitations, t… ▽ More Charged particle precipitation typically manifests as a gradual increase and decrease of flux observed by space detectors. Cases with rapidly flux variation are very rare. Periodic events are even more extraordinary. These oscillating particle precipitation (OPP) events are usually attributed to the bounce motion of electrons, which are induced by lightning. Owing to the observation limitations, there has been debate regarding whether these oscillations originate from temporal flux evolution or spatial structure evolution. Here we report three peculiar charged particle precipitation events detected by GECAM during a geomagnetic storm on March 21, 2024, with two exhibiting significant periodicity. These events were observed around the same region during three consecutive orbits. Through comprehensive temporal and spectral analyses, we revealed that one of the OPP events exhibited a transition in spectral lag of mini-pulses, shifting from "softer-earlier" to "softer-later" while showing no significant time evolution in overall frequency characteristics. And there is no association found between these two OPP events and lightning activity. Several possible scenarios are discussed to explain these charged particles with a life time of more than 3.5 hours, but the nature of these three events remains an enigma. We suggest that these GECAM-detected OPP events may represent a new type of particle precipitation event or a peculiar Lightning-induced Electron Precipitations (LEPs). △ Less

Submitted 9 May, 2025; originally announced May 2025.

Imbibition of Oil in Dry and Prewetted Calcite Nanopores

Authors: Ejaz Ahmed, Huajie Zhang, Mert Aybar, Bikai Jin, Shihao Wang, Rui Qiao

Abstract: Fluid imbibition into porous media featuring nanopores is ubiquitous in applications such as oil recovery from unconventional reservoirs and material processing. While the imbibition of pure fluids has been extensively studied, the imbibition of fluid mixture is little explored. Here we report the molecular dynamics study of the imbibition of model crude oil into nanometer-wide mineral pores, both… ▽ More Fluid imbibition into porous media featuring nanopores is ubiquitous in applications such as oil recovery from unconventional reservoirs and material processing. While the imbibition of pure fluids has been extensively studied, the imbibition of fluid mixture is little explored. Here we report the molecular dynamics study of the imbibition of model crude oil into nanometer-wide mineral pores, both when pore walls are dry and prewetted by a residual water film. Results show the fastest imbibition and quickest propagation of molecularly thin precursor films ahead of the oil meniscus in the dry pore system. The presence of a thin water film on pore walls corresponding to an environmental relative humidity of 30% slows down but still allows the spontaneous imbibition of single-component oil. Introducing polar components into the oil slows down the imbibition into dry nanopores, due partly to the clogging of the pore entrance. Strong selectivity toward nonpolar oil is evident. The slowdown of imbibition by polar oil is less significant in the prewetted pores than in dry pores, but the selectivity toward nonpolar oil remains strong. △ Less

Submitted 6 April, 2025; originally announced April 2025.

Comments: 24 pages, 8 figures, Submitted to Physics of Fluids, Rui Qiao: To whom correspondence should be addressed. Email: ruiqiao@vt.edu

Journal ref: Phys. Fluids 37, 072038 (2025)

Capacitive coupling study of the HERD SCD prototype: preliminary results

Authors: Ruo-Si Lu, Rui Qiao, Ke Gong, Wen-Xi Peng, Wei-Shuai Zhang, Dong-Ya Guo, Jia-Ju Wei, Yi-Ming Hu, Jian-Hua Guo, Qi Wu, Peng Hu, Xuan Liu, Bing Lu, Yi-Rong Zhang

Abstract: The Silicon Charge Detector (SCD) is a subdetector of the High Energy Cosmic Radiation Detection payload. The dynamic range of the silicon microstrip detector can be extended by the capacitive coupling effect, which is related to the interstrip capacitance and the coupling capacitance. A detector prototype with several sets of parameters was designed and tested in the ion beams at the CERN Super P… ▽ More The Silicon Charge Detector (SCD) is a subdetector of the High Energy Cosmic Radiation Detection payload. The dynamic range of the silicon microstrip detector can be extended by the capacitive coupling effect, which is related to the interstrip capacitance and the coupling capacitance. A detector prototype with several sets of parameters was designed and tested in the ion beams at the CERN Super Proton Synchrotron. The capacitive coupling fractions with readout strip and floating strip incidences were studied using the beam test data and SPICE simulation. △ Less

Submitted 27 February, 2024; originally announced February 2024.

Inertia and slip effects on the instability of a liquid film coated on a fibre

Authors: Chengxi Zhao, Ran Qiao, Kai Mu, Ting Si, Xisheng Luo

Abstract: To investigate the influence of inertia and slip on the instability of a liquid film on a fibre, a theoretical framework based on the axisymmetric Navier-Stokes equations is proposed via linear instability analysis. The model reveals that slip significantly enhances perturbation growth in viscous film flows, whereas it exerts minimal influence on flows dominated by inertia. Moreover, under no-slip… ▽ More To investigate the influence of inertia and slip on the instability of a liquid film on a fibre, a theoretical framework based on the axisymmetric Navier-Stokes equations is proposed via linear instability analysis. The model reveals that slip significantly enhances perturbation growth in viscous film flows, whereas it exerts minimal influence on flows dominated by inertia. Moreover, under no-slip boundary conditions, the dominant instability mode of thin films remains unaltered by inertia, closely aligning with predictions from a no-slip lubrication model. Conversely, when slip is introduced, the dominant wavenumber experiences a noticeable reduction as inertia decreases. This trend is captured by an introduced lubrication model with giant slip. Direct numerical simulations of the Navier-Stokes equations are then performed to further confirm the theoretical findings at the linear stage. For the nonlinear dynamics, no-slip simulations show complex vortical structures within films, driven by fluid inertia near surfaces. Additionally, in scenarios with weak inertia, a reduction in the volume of satellite droplets is observed due to slip, following a power-law relationship. △ Less

Submitted 31 January, 2024; originally announced February 2024.

Point convolutional neural network algorithm for Ising model ground state research based on spring vibration

Authors: Zhelong Jiang, Gang Chen, Ruixiu Qiao, Pengcheng Feng, Yihao Chen, Junjia Su, Zhiyuan Zhao, Min Jin, Xu Chen, Zhigang Li, Huaxiang Lu

Abstract: The ground state search of the Ising model can be used to solve many combinatorial optimization problems. Under the current computer architecture, an Ising ground state search algorithm suitable for hardware computing is necessary for solving practical problems. Inspired by the potential energy conversion of springs, we propose a point convolutional neural network algorithm for ground state search… ▽ More The ground state search of the Ising model can be used to solve many combinatorial optimization problems. Under the current computer architecture, an Ising ground state search algorithm suitable for hardware computing is necessary for solving practical problems. Inspired by the potential energy conversion of springs, we propose a point convolutional neural network algorithm for ground state search based on spring vibration model, called Spring-Ising Algorithm. Spring-Ising Algorithm regards the spin as a moving mass point connected to a spring and establish the equation of motion for all spins. Spring-Ising Algorithm can be mapped on the GPU or AI chips through the basic structure of the neural network for fast and efficient parallel computing. The algorithm has very productive results for solving the Ising model and has been test in the recognized test benchmark K2000. The algorithm introduces the concept of dynamic equilibrium to achieve a more detailed local search by dynamically adjusting the weight of the Ising model in the spring oscillation model. Finally, there is the simple hardware test speed evaluation. Spring-Ising Algorithm can provide the possibility to calculate the Ising model on a chip which focuses on accelerating neural network calculations. △ Less

Submitted 11 May, 2023; originally announced May 2023.

Comments: 15 pages, 6 figures

Ground calibration of Gamma-Ray Detectors of GECAM-C

Authors: Chao Zheng, Zheng-Hua An, Wen-Xi Peng, Da-Li Zhang, Shao-Lin Xiong, Rui. Qiao, Yan-Qiu Zhang, Wang-Chen Xue, Jia-Cong Liu, Pei-Yi Feng, Ce. Cai, Min Gao, Ke Gong, Dong-Ya Guo, Dong-Jie Hou, Gang Li, Xin-Qiao Li, Yan-Guo Li, Mao-Shun Li, Xiao-Hua Liang, Ya-Qing Liu, Xiao-Jing Liu, Li-Ming Song, Xi-Lei Sun, Wen-Jun Tan , et al. (13 additional authors not shown)

Abstract: As a new member of GECAM mission, GECAM-C (also named High Energy Burst Searcher, HEBS) was launched onboard the SATech-01 satellite on July 27th, 2022, which is capable to monitor gamma-ray transients from $\sim$ 6 keV to 6 MeV. As the main detector, there are 12 gamma-ray detectors (GRDs) equipped for GECAM-C. In order to verify the GECAM-C GRD detector performance and to validate the Monte Carl… ▽ More As a new member of GECAM mission, GECAM-C (also named High Energy Burst Searcher, HEBS) was launched onboard the SATech-01 satellite on July 27th, 2022, which is capable to monitor gamma-ray transients from $\sim$ 6 keV to 6 MeV. As the main detector, there are 12 gamma-ray detectors (GRDs) equipped for GECAM-C. In order to verify the GECAM-C GRD detector performance and to validate the Monte Carlo simulations of detector response, comprehensive on-ground calibration experiments have been performed using X-ray beam and radioactive sources, including Energy-Channel relation, energy resolution, detection efficiency, SiPM voltage-gain relation and the non-uniformity of positional response. In this paper, the detailed calibration campaigns and data analysis results for GECAM-C GRDs are presented, demonstrating the excellent performance of GECAM-C GRD detectors. △ Less

Submitted 30 May, 2023; v1 submitted 1 March, 2023; originally announced March 2023.

Comments: third version

The performance of SiPM-based gamma-ray detector (GRD) of GECAM-C

Authors: Dali Zhang, Chao Zheng, Jiacong Liu, Zhenghua An, Chenwei Wang, Xiangyang Wen, Xinqiao Li, Xilei Sun, Ke Gong, Yaqing Liu, Xiaojing Liu, Sheng Yang, Wenxi Peng, Rui Qiao, Dongya Guo, Peiyi Feng, Yanqiu Zhang, Wangchen Xue, Wenjun Tan, Ce Cai, Shuo Xiao, Qibin Yi, Yanbing Xu, Min Gao, Jinzhou Wang , et al. (20 additional authors not shown)

Abstract: As a new member of GECAM mission, the GECAM-C (also called High Energy Burst Searcher, HEBS) is a gamma-ray all-sky monitor onboard SATech-01 satellite, which was launched on July 27th, 2022 to detect gamma-ray transients from 6 keV to 6 MeV, such as Gamma-Ray Bursts (GRBs), high energy counterpart of Gravitational Waves (GWs) and Fast Radio Bursts (FRBs), and Soft Gamma-ray Repeaters (SGRs). Toge… ▽ More As a new member of GECAM mission, the GECAM-C (also called High Energy Burst Searcher, HEBS) is a gamma-ray all-sky monitor onboard SATech-01 satellite, which was launched on July 27th, 2022 to detect gamma-ray transients from 6 keV to 6 MeV, such as Gamma-Ray Bursts (GRBs), high energy counterpart of Gravitational Waves (GWs) and Fast Radio Bursts (FRBs), and Soft Gamma-ray Repeaters (SGRs). Together with GECAM-A and GECAM-B launched in December 2020, GECAM-C will greatly improve the monitoring coverage, localization, as well as temporal and spectral measurements of gamma-ray transients. GECAM-C employs 12 SiPM-based Gamma-Ray Detectors (GRDs) to detect gamma-ray transients . In this paper, we firstly give a brief description of the design of GECAM-C GRDs, and then focus on the on-ground tests and in-flight performance of GRDs. We also did the comparison study of the SiPM in-flight performance between GECAM-C and GECAM-B. The results show GECAM-C GRD works as expected and is ready to make scientific observations. △ Less

Submitted 7 March, 2023; v1 submitted 1 March, 2023; originally announced March 2023.

Comments: 18 pages, 16 figures

Search for relativistic fractionally charged particles in space

Authors: DAMPE Collaboration, F. Alemanno, C. Altomare, Q. An, P. Azzarello, F. C. T. Barbato, P. Bernardini, X. J. Bi, M. S. Cai, E. Casilli, E. Catanzani, J. Chang, D. Y. Chen, J. L. Chen, Z. F. Chen, M. Y. Cui, T. S. Cui, Y. X. Cui, H. T. Dai, A. De-Benedittis, I. De Mitri, F. de Palma, M. Deliyergiyev, A. Di Giovanni, M. Di Santo , et al. (126 additional authors not shown)

Abstract: More than a century after the performance of the oil drop experiment, the possible existence of fractionally charged particles FCP still remains unsettled. The search for FCPs is crucial for some extensions of the Standard Model in particle physics. Most of the previously conducted searches for FCPs in cosmic rays were based on experiments underground or at high altitudes. However, there have been… ▽ More More than a century after the performance of the oil drop experiment, the possible existence of fractionally charged particles FCP still remains unsettled. The search for FCPs is crucial for some extensions of the Standard Model in particle physics. Most of the previously conducted searches for FCPs in cosmic rays were based on experiments underground or at high altitudes. However, there have been few searches for FCPs in cosmic rays carried out in orbit other than AMS-01 flown by a space shuttle and BESS by a balloon at the top of the atmosphere. In this study, we conduct an FCP search in space based on on-orbit data obtained using the DArk Matter Particle Explorer (DAMPE) satellite over a period of five years. Unlike underground experiments, which require an FCP energy of the order of hundreds of GeV, our FCP search starts at only a few GeV. An upper limit of $6.2\times 10^{-10}~~\mathrm{cm^{-2}sr^{-1} s^{-1}}$ is obtained for the flux. Our results demonstrate that DAMPE exhibits higher sensitivity than experiments of similar types by three orders of magnitude that more stringently restricts the conditions for the existence of FCP in primary cosmic rays. △ Less

Submitted 9 September, 2022; originally announced September 2022.

Comments: 19 pages, 6 figures, accepted by PRD

Report number: 106, 063026

Journal ref: Physical Review D 106.6 (2022): 063026

Temperature effect on non-Darcian flow in low-permeability porous media

Authors: Yuntian Teng, Yifeng Wang, Zihao Li, Rui Qiao, Cheng Chen

Abstract: In low-permeability porous media, the velocity of a fluid flow exhibits a nonlinear dependence on the imposed pressure gradient. This non-Darcian flow behavior has important implications to geological disposal of nuclear waste, hydrocarbon extraction from shale, and flow and transport in clay-rich aquifers. Temperature has been postulated to affect the threshold pressure gradient of a non-Darcian… ▽ More In low-permeability porous media, the velocity of a fluid flow exhibits a nonlinear dependence on the imposed pressure gradient. This non-Darcian flow behavior has important implications to geological disposal of nuclear waste, hydrocarbon extraction from shale, and flow and transport in clay-rich aquifers. Temperature has been postulated to affect the threshold pressure gradient of a non-Darcian flow; however, the supporting data is very limited. In this study we for the first time report a systematic measurement of the threshold pressure gradient under various permeabilities and temperatures. The results show that a higher temperature leads to a lower threshold pressure gradient under the same permeability and a faster reduction of the threshold pressure gradient with increasing permeability. The experimental data are fitted to a two-parameter model to determine the parameters, h0 and a, which characterize the interfacial fluid-solid interactions and the transition between the Darcy and non-Darcian regimes. △ Less

Submitted 3 August, 2022; originally announced August 2022.

Inflight performance of the GECAM Gamma-ray and Charge particle Detectors

Authors: X. Q. Li, X. Y. Wen, S. L. Xiong, K. Gong, D. L. Zhang, Z. H. An, Y. B. Xu, Y. Q. Liu, C. Cai, Z. Chang, G. Chen, C. Chen, Y. Y. Du, M. Gao, R. Gao, D. Y. Guo, J. J. He, D. J. Hou, Y. G. Li, C. Li, C. Y. Li, G. Li, L. Li, Q. X. Li, X. F. Li , et al. (34 additional authors not shown)

Abstract: The GECAM mission consists of two identical microsatellites (GECAM-A and GECAM-B). Each satellite is equipped with 25 gamma-ray detectors (GRD) and 8 charged particle detectors (CPD). The main scientific objective of the GECAM mission is to detect gamma-ray bursts (GRBs) associated with the gravitational wave events produced by the merging of binary compact stars. After the launch on Dec. 10, 2020… ▽ More The GECAM mission consists of two identical microsatellites (GECAM-A and GECAM-B). Each satellite is equipped with 25 gamma-ray detectors (GRD) and 8 charged particle detectors (CPD). The main scientific objective of the GECAM mission is to detect gamma-ray bursts (GRBs) associated with the gravitational wave events produced by the merging of binary compact stars. After the launch on Dec. 10, 2020 , we carried out a series of on orbit tests. This paper introduces the test results of the GECAM-B satellite. According to the in-flight performance, the energy band for gamma-ray detection of GECAM-B is from about 7 keV to 3.5 MeV. GECAM-B can achieve prompt localization of GRBs. For the first time, GECAM-B realized a quasi-real-time transmission of trigger information using Beidou-3 RDSS. Keywords GECAM, gamma-ray burst, gravitational wave, GRD, CPD △ Less

Submitted 9 December, 2021; originally announced December 2021.

Comments: 16 pages, 8 figures

Gain stabilization and consistency correction approach for multiple SiPM-based gamma-ray detectors on GECAM

Authors: Dali Zhang, Xinqiao Li, Xiangyang Wen, Shaolin Xiong, Zhenghua An, Xilei Sun, Rui Qiao, Zhengwei Li, Ke Gong, Dongjie Hou, Yanguo Li, Xiaohua Liang, Xiaojing Liu, Yaqing Liu, Wenxi Peng, Sheng Yang, Fan Zhang, Xiaoyun Zhao, Ce Cai, Chaoyang Li, Jiacong Liu, Shuo Xiao, Chenwei Wang, Qibin Yi, Chao Zheng

Abstract: Each satellite of the Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM, mission) consists of 25 SiPM based gamma-ray detectors (GRDs). Although SiPM based GRD has merits of compact size and low bias-voltage, the drift of the SiPM gain with temperature is a severe problem for GRD performance. An adaptive voltage supply source was designed to automatically adjust the… ▽ More Each satellite of the Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM, mission) consists of 25 SiPM based gamma-ray detectors (GRDs). Although SiPM based GRD has merits of compact size and low bias-voltage, the drift of the SiPM gain with temperature is a severe problem for GRD performance. An adaptive voltage supply source was designed to automatically adjust the SiPM bias voltage to compensate the temperature effects and keep the gain stable. This approach has been proved to be effective during both the on-ground and in-flight tests. The in-flight measured variation of the SiPM gain is within 2%. To reduce the gain non-uniformity of GRDs, an iterative bias voltage adjustment approach is proposed and implemented. The gain non-uniformity is reduced from 17% to 0.6%. In this paper, the gain stabilization and consistency correction approach are presented and discussed in detail. △ Less

Submitted 9 December, 2021; v1 submitted 4 October, 2021; originally announced October 2021.

Comments: 14 pages, 21 figures

Disparate exciton-phonon couplings for zone center and boundary phonons in solid-state graphite

Authors: Xuefei Feng, Shawn Sallis, Yu-Cheng Shao, Ruimin Qiao, Yi-Sheng Liu, Li Cheng Kao, Anton Tremsin, Zahid Hussain, Wanli Yang, Jinghua Guo, Yi-De Chuang

Abstract: The exciton-phonon coupling in highly oriented pyrolytic graphite is studied using resonant inelastic X-ray scattering (RIXS) spectroscopy. With ~ 70 meV energy resolution, multiple low energy excitations associated with coupling to phonons can be clearly resolved in RIXS spectra. Using resonance dependence and the closed form for RIXS cross-section without considering the intermediate state mixin… ▽ More The exciton-phonon coupling in highly oriented pyrolytic graphite is studied using resonant inelastic X-ray scattering (RIXS) spectroscopy. With ~ 70 meV energy resolution, multiple low energy excitations associated with coupling to phonons can be clearly resolved in RIXS spectra. Using resonance dependence and the closed form for RIXS cross-section without considering the intermediate state mixing of phonon modes, the dimensionless coupling constant g is determined to be 5 and 0.4, corresponding to the coupling strength of 0.42 eV +/- 40 meV and 0.21 eV +/- 30 meV, for zone center and boundary phonons respectively. The reduced g value for zone-boundary phonon may be related to its double resonance nature. △ Less

Submitted 5 January, 2020; originally announced January 2020.

Comments: Main text is 20 pages with 4 figures Supplementary information is 10 pages with 3 figures

Journal ref: Phys. Rev. Lett. 125, 116401 (2020)

Predicting Effective Diffusivity of Porous Media from Images by Deep Learning

Authors: Haiyi Wu, Wen-Zhen Fang, Qinjun Kang, Wen-Quan Tao, Rui Qiao

Abstract: We report the application of machine learning methods for predicting the effective diffusivity (De) of two-dimensional porous media from images of their structures. Pore structures are built using reconstruction methods and represented as images, and their effective diffusivity is computed by lattice Boltzmann (LBM) simulations. The datasets thus generated are used to train convolutional neural ne… ▽ More We report the application of machine learning methods for predicting the effective diffusivity (De) of two-dimensional porous media from images of their structures. Pore structures are built using reconstruction methods and represented as images, and their effective diffusivity is computed by lattice Boltzmann (LBM) simulations. The datasets thus generated are used to train convolutional neural network (CNN) models and evaluate their performance. The trained model predicts the effective diffusivity of porous structures with computational cost orders of magnitude lower than LBM simulations. The optimized model performs well on porous media with realistic topology, large variation of porosity (0.28-0.98), and effective diffusivity spanning more than one order of magnitude (), e.g., >95% of predicted De have truncated relative error of <10% when the true De is larger than 0.2. The CNN model provides better prediction than the empirical Bruggeman equation, especially for porous structure with small diffusivity. The relative error of CNN predictions, however, is rather high for structures with De < 0.1. To address this issue, the porosity of porous structures is encoded directly into the neural network but the performance is enhanced marginally. Further improvement, i.e., 70% of the CNN predictions for structures with true De < 0.1 have relative error <30%, is achieved by removing trapped regions and dead-end pathways using a simple algorithm. These results suggest that deep learning augmented by field knowledge can be a powerful technique for predicting the transport properties of porous media. Directions for future research of machine learning in porous media are discussed based on detailed analysis of the performance of CNN models in the present work. △ Less

Submitted 2 December, 2019; originally announced December 2019.

Charge Measurement of Cosmic Ray Nuclei with the Plastic Scintillator Detector of DAMPE

Authors: Tiekuang Dong, Yapeng Zhang, Pengxiong Ma, Yongjie Zhang, Paolo Bernardini, Meng Ding, Dongya Guo, Shijun Lei, Xiang Li, Ivan De Mitri, Wenxi Peng, Rui Qiao, Margherita Di Santo, Zhiyu Sun, Antonio Surdo, Zhaomin Wang, Jian Wu, Zunlei Xu, Yuhong Yu, Qiang Yuan, Chuan Yue, Jingjing Zang, Yunlong Zhang

Abstract: One of the main purposes of the DArk Matter Particle Explorer (DAMPE) is to measure the cosmic ray nuclei up to several tens of TeV or beyond, whose origin and propagation remains a hot topic in astrophysics. The Plastic Scintillator Detector (PSD) on top of DAMPE is designed to measure the charges of cosmic ray nuclei from H to Fe and serves as a veto detector for discriminating gamma-rays from c… ▽ More One of the main purposes of the DArk Matter Particle Explorer (DAMPE) is to measure the cosmic ray nuclei up to several tens of TeV or beyond, whose origin and propagation remains a hot topic in astrophysics. The Plastic Scintillator Detector (PSD) on top of DAMPE is designed to measure the charges of cosmic ray nuclei from H to Fe and serves as a veto detector for discriminating gamma-rays from charged particles. We propose in this paper a charge reconstruction procedure to optimize the PSD performance in charge measurement. Essentials of our approach, including track finding, alignment of PSD, light attenuation correction, quenching and equalization correction are described detailedly in this paper after a brief description of the structure and operational principle of the PSD. Our results show that the PSD works very well and almost all the elements in cosmic rays from H to Fe are clearly identified in the charge spectrum. △ Less

Submitted 25 October, 2018; originally announced October 2018.

Comments: 20 pages, 4 figures

Journal ref: Astroparticle Physics 105 (2019) 31-36

In-flight performance of the DAMPE silicon tracker

Authors: A. Tykhonov, G. Ambrosi, R. Asfandiyarov, P. Azzarello, P. Bernardini, B. Bertucci, A. Bolognini, F. Cadoux, A. D'Amone, A. De Benedittis, I. De Mitri, M. Di Santo, Y. F. Dong, M. Duranti, D. D'Urso, R. R. Fan, P. Fusco, V. Gallo, M. Gao, F. Gargano, S. Garrappa, K. Gong, M. Ionica, D. La Marra, F. Loparco , et al. (17 additional authors not shown)

Abstract: DAMPE (DArk Matter Particle Explorer) is a spaceborne high-energy cosmic ray and gamma-ray detector, successfully launched in December 2015. It is designed to probe astroparticle physics in the broad energy range from few GeV to 100 TeV. The scientific goals of DAMPE include the identification of possible signatures of Dark Matter annihilation or decay, the study of the origin and propagation mech… ▽ More DAMPE (DArk Matter Particle Explorer) is a spaceborne high-energy cosmic ray and gamma-ray detector, successfully launched in December 2015. It is designed to probe astroparticle physics in the broad energy range from few GeV to 100 TeV. The scientific goals of DAMPE include the identification of possible signatures of Dark Matter annihilation or decay, the study of the origin and propagation mechanisms of cosmic-ray particles, and gamma-ray astronomy. DAMPE consists of four sub-detectors: a plastic scintillator strip detector, a Silicon-Tungsten tracKer-converter (STK), a BGO calorimeter and a neutron detector. The STK is composed of six double layers of single-sided silicon micro-strip detectors interleaved with three layers of tungsten for photon conversions into electron-positron pairs. The STK is a crucial component of DAMPE, allowing to determine the direction of incoming photons, to reconstruct tracks of cosmic rays and to estimate their absolute charge (Z). We present the in-flight performance of the STK based on two years of in-flight DAMPE data, which includes the noise behavior, signal response, thermal and mechanical stability, alignment and position resolution. △ Less

Submitted 27 June, 2018; originally announced June 2018.

Journal ref: Nucl. Instrum. Methods Phys. Res. A 924 (2019) 309-315

A machine learning method to separate cosmic ray electrons from protons from 10 to 100 GeV using DAMPE data

Authors: Hao Zhao, Wen-Xi Peng, Huan-Yu Wang, Rui Qiao, Dong-Ya Guo, Hong Xiao, Zhao-Min Wang

Abstract: DArk Matter Particle Explorer (DAMPE) is a general purpose high energy cosmic ray and gamma ray observatory, aiming to detect high energy electrons and gammas in the energy range 5 GeV to 10 TeV and hundreds of TeV for nuclei. This paper provides a method using machine learning to identify electrons and separate them from gammas,protons,helium and heavy nuclei with the DAMPE data from 2016 January… ▽ More DArk Matter Particle Explorer (DAMPE) is a general purpose high energy cosmic ray and gamma ray observatory, aiming to detect high energy electrons and gammas in the energy range 5 GeV to 10 TeV and hundreds of TeV for nuclei. This paper provides a method using machine learning to identify electrons and separate them from gammas,protons,helium and heavy nuclei with the DAMPE data from 2016 January 1 to 2017 June 30, in energy range from 10 to 100 GeV. △ Less

Submitted 21 June, 2018; v1 submitted 18 March, 2018; originally announced March 2018.

Comments: 11 pages, 8 figures, accepted for publication in RAA. arXiv admin note: text overlap with arXiv:physics/0703039 by other authors

A new charge reconstruction algorithm for the DAMPE silicon microstrip detector

Authors: Rui Qiao, Wen-Xi Peng, Dong-Ya Guo, Hao Zhao, Huan-Yu Wang, Ke Gong, Fei Zhang

Abstract: The DArk Matter Particle Explorer (DAMPE) is one of the four satellites within the Strategic Pioneer Research Program in Space Science of the Chinese Academy of Science (CAS). The Silicon-Tungsten Tracker (STK), which is composed of 768 singled-sided silicon microstrip detectors, is one of the four subdetectors in DAMPE, providing track reconstruction and charge identification for relativistic cha… ▽ More The DArk Matter Particle Explorer (DAMPE) is one of the four satellites within the Strategic Pioneer Research Program in Space Science of the Chinese Academy of Science (CAS). The Silicon-Tungsten Tracker (STK), which is composed of 768 singled-sided silicon microstrip detectors, is one of the four subdetectors in DAMPE, providing track reconstruction and charge identification for relativistic charged particles. The charge response of DAMPE silicon microstrip detectors is complicated, depending on the incident angle and impact position. A new charge reconstruction algorithm for the DAMPE silicon microstrip detector is introduced in this paper. This algorithm can correct the complicated charge response, and was proved applicable by the ion test beam. △ Less

Submitted 21 December, 2017; originally announced December 2017.

Comments: 7 pages, 8 figures

Internal alignment and position resolution of the silicon tracker of DAMPE determined with orbit data

Authors: A. Tykhonov, G. Ambrosi, R. Asfandiyarov, P. Azzarello, P. Bernardini, B. Bertucci, A. Bolognini, F. Cadoux, A. D'Amone, A. De Benedittis, I. De Mitri, M. Di Santo, Y. F. Dong, M. Duranti, D. D'Urso, R. R. Fan, P. Fusco, V. Gallo, M. Gao, F. Gargano, S. Garrappa, K. Gong, M. Ionica, D. La Marra, S. J. Lei , et al. (18 additional authors not shown)

Abstract: The DArk Matter Particle Explorer (DAMPE) is a space-borne particle detector designed to probe electrons and gamma-rays in the few GeV to 10 TeV energy range, as well as cosmic-ray proton and nuclei components between 10 GeV and 100 TeV. The silicon-tungsten tracker-converter is a crucial component of DAMPE. It allows the direction of incoming photons converting into electron-positron pairs to be… ▽ More The DArk Matter Particle Explorer (DAMPE) is a space-borne particle detector designed to probe electrons and gamma-rays in the few GeV to 10 TeV energy range, as well as cosmic-ray proton and nuclei components between 10 GeV and 100 TeV. The silicon-tungsten tracker-converter is a crucial component of DAMPE. It allows the direction of incoming photons converting into electron-positron pairs to be estimated, and the trajectory and charge (Z) of cosmic-ray particles to be identified. It consists of 768 silicon micro-strip sensors assembled in 6 double layers with a total active area of 6.6 m$^2$. Silicon planes are interleaved with three layers of tungsten plates, resulting in about one radiation length of material in the tracker. Internal alignment parameters of the tracker have been determined on orbit, with non-showering protons and helium nuclei. We describe the alignment procedure and present the position resolution and alignment stability measurements. △ Less

Submitted 22 March, 2018; v1 submitted 7 December, 2017; originally announced December 2017.

Journal ref: Nucl. Instrum. Methods Phys. Res. A 893 (2018) 43-56

The DArk Matter Particle Explorer mission

Authors: J. Chang, G. Ambrosi, Q. An, R. Asfandiyarov, P. Azzarello, P. Bernardini, B. Bertucci, M. S. Cai, M. Caragiulo, D. Y. Chen, H. F. Chen, J. L. Chen, W. Chen, M. Y. Cui, T. S. Cui, A. D'Amone, A. De Benedittis, I. De Mitri, M. Di Santo, J. N. Dong, T. K. Dong, Y. F. Dong, Z. X. Dong, G. Donvito, D. Droz , et al. (139 additional authors not shown)

Abstract: The DArk Matter Particle Explorer (DAMPE), one of the four scientific space science missions within the framework of the Strategic Pioneer Program on Space Science of the Chinese Academy of Sciences, is a general purpose high energy cosmic-ray and gamma-ray observatory, which was successfully launched on December 17th, 2015 from the Jiuquan Satellite Launch Center. The DAMPE scientific objectives… ▽ More The DArk Matter Particle Explorer (DAMPE), one of the four scientific space science missions within the framework of the Strategic Pioneer Program on Space Science of the Chinese Academy of Sciences, is a general purpose high energy cosmic-ray and gamma-ray observatory, which was successfully launched on December 17th, 2015 from the Jiuquan Satellite Launch Center. The DAMPE scientific objectives include the study of galactic cosmic rays up to $\sim 10$ TeV and hundreds of TeV for electrons/gammas and nuclei respectively, and the search for dark matter signatures in their spectra. In this paper we illustrate the layout of the DAMPE instrument, and discuss the results of beam tests and calibrations performed on ground. Finally we present the expected performance in space and give an overview of the mission key scientific goals. △ Less

Submitted 14 September, 2017; v1 submitted 26 June, 2017; originally announced June 2017.

Comments: 45 pages, including 29 figures and 6 tables. Published in Astropart. Phys

Journal ref: Astropart. Phys. 95 (2017) 6-24

Charge reconstruction study of the DAMPE Silicon-Tungsten Tracker with ion beams

Authors: Rui Qiao, Wen-Xi Peng, Dong-Ya Guo, Hao Zhao, Huan-Yu Wang, Ke Gong, Fei Zhang, Xin Wu, Phillip Azzarello, Andrii Tykhonov, Ruslan Asfandiyarov, Valentina Gallo, Giovanni Ambrosi, Nicola Mazziotta, Ivan De Mitri

Abstract: The DArk Matter Particle Explorer (DAMPE) is one of the four satellites within Strategic Pioneer Research Program in Space Science of the Chinese Academy of Science (CAS). DAMPE can detect electrons, photons in a wide energy range (5 GeV to 10 TeV) and ions up to iron (100GeV to 100 TeV). Silicon-Tungsten Tracker (STK) is one of the four subdetectors in DAMPE, providing photon-electron conversion,… ▽ More The DArk Matter Particle Explorer (DAMPE) is one of the four satellites within Strategic Pioneer Research Program in Space Science of the Chinese Academy of Science (CAS). DAMPE can detect electrons, photons in a wide energy range (5 GeV to 10 TeV) and ions up to iron (100GeV to 100 TeV). Silicon-Tungsten Tracker (STK) is one of the four subdetectors in DAMPE, providing photon-electron conversion, track reconstruction and charge identification for ions. Ion beam test was carried out in CERN with 60GeV/u Lead primary beams. Charge reconstruction and charge resolution of STK detectors were investigated. △ Less

Submitted 27 May, 2017; originally announced May 2017.

Comments: 7 pages, 8 figures

Ultrafast field-driven monochromatic photoemission from carbon nanotubes

Authors: Chi Li, Xu Zhou, Feng Zhai, Zhenjun Li, Fengrui Yao, Ruixi Qiao, Ke Chen, Matthew T. Cole, Dapeng Yu, Zhipei Sun, Kaihui Liu, Qing Dai

Abstract: Ultrafast electron pulses, combined with laser-pump and electron-probe technologies, allow for various forms of ultrafast microscopy and spectroscopy to elucidate otherwise challenging to observe physical and chemical transitions. However, the pursuit of simultaneous ultimate spatial and temporal resolution has been largely subdued by the low monochromaticity of the electron pulses and their poor… ▽ More Ultrafast electron pulses, combined with laser-pump and electron-probe technologies, allow for various forms of ultrafast microscopy and spectroscopy to elucidate otherwise challenging to observe physical and chemical transitions. However, the pursuit of simultaneous ultimate spatial and temporal resolution has been largely subdued by the low monochromaticity of the electron pulses and their poor phase synchronization to the optical excitation pulses. State-of-the-art photon-driven sources have good monochromaticity but poor phase synchronization. In contrast, field-driven photoemission has much higher light phase synchronization, due to the intrinsic sub-cycle emission dynamics, but poor monochromaticity. Such sources suffer from larger electron energy spreads (3 - 100 eV) attributed to the relatively low field enhancement of the conventional metal tips which necessitates long pump wavelengths (> 800 nm) in order to gain sufficient ponderomotive potential to access the field-driven regime. In this work, field-driven photoemission from ~1 nm radius carbon nanotubes excited by a femtosecond laser at a short wavelength of 410 nm has been realized. The energy spread of field-driven electrons is effectively compressed to 0.25 eV outperforming all conventional ultrafast electron sources. Our new nanotube-based ultrafast electron source opens exciting prospects for attosecond imaging and emerging light-wave electronics. △ Less

Submitted 7 February, 2017; originally announced February 2017.

Ion beam test results of the Plastic Scintillator Detector of DAMPE

Authors: Rui Qiao, Wen-Xi Peng, Dong-Ya Guo, Hao Zhao, Huan-Yu Wang

Abstract: The DArk Matter Particle Explorer (DAMPE) is one of the four satellites within Strategic Pioneer Research Program in Space Science of the Chinese Academy of Science (CAS). DAMPE can detect electrons, photons and ions in a wide energy range (5 GeV to 10 TeV) and ions up to iron (100GeV to 100 TeV). Plastic Scintillator Detector (PSD) is one of the four payloads in DAMPE, providing e/γ separation an… ▽ More The DArk Matter Particle Explorer (DAMPE) is one of the four satellites within Strategic Pioneer Research Program in Space Science of the Chinese Academy of Science (CAS). DAMPE can detect electrons, photons and ions in a wide energy range (5 GeV to 10 TeV) and ions up to iron (100GeV to 100 TeV). Plastic Scintillator Detector (PSD) is one of the four payloads in DAMPE, providing e/γ separation and charge identification up to Iron. An ion beam test was carried out for the Qualification Model of PSD in CERN with 40GeV/u Argon primary beams. The Birk's saturation and charge resolution of PSD were investigated. △ Less

Submitted 19 January, 2017; v1 submitted 18 January, 2017; originally announced January 2017.

Comments: This paper has been withdrawn by the author due to some errors in section 3.2.2

Super-Diffusive Gas Recovery from Nanopores

Authors: Haiyi Wu, Yadong He, Rui Qiao

Abstract: Understanding the recovery of gas from reservoirs featuring pervasive nanopores is essential for effective shale gas extraction. Classical theories cannot accurately predict such gas recovery and many experimental observations are not well understood. Here we report molecular simulations of the recovery of gas from single nanopores, explicitly taking into account molecular gas-wall interactions. W… ▽ More Understanding the recovery of gas from reservoirs featuring pervasive nanopores is essential for effective shale gas extraction. Classical theories cannot accurately predict such gas recovery and many experimental observations are not well understood. Here we report molecular simulations of the recovery of gas from single nanopores, explicitly taking into account molecular gas-wall interactions. We show that, in very narrow pores, the strong gas-wall interactions are essential in determining the gas recovery behavior both quantitatively and qualitatively. These interactions cause the total diffusion coefficients of the gas molecules in nanopores to be smaller than those predicted by kinetic theories, hence slowing down the rate of gas recovery. These interactions also lead to significant adsorption of gas molecules on the pore walls. Because of the desorption of these gas molecules during gas recovery, the gas recovery from the nanopore does not exhibit the usual diffusive scaling law (i.e., the accumulative recovery scales as $R \sim t^{1/2}$ but follows a super-diffusive scaling law $R \sim t^n$ ($n>0.5$), which is similar to that observed in some field experiments. For the system studied here, the super-diffusive gas recovery scaling law can be captured well by continuum models in which the gas adsorption and desorption from pore walls are taken into account using the Langmuir model. △ Less

Submitted 16 October, 2016; originally announced October 2016.

Comments: seven figures

Journal ref: Phys. Rev. Fluids 1, 074101 (2016)

Design of the readout electronics for the DAMPE Silicon Tracker detector

Authors: Fei Zhang, Wen-Xi Peng, Ke Gong, Di Wu, Yi-Fan Dong, Rui Qiao, Rui-Rui Fan, Jin-Zhou Wang, Huan-Yu Wang, Xin Wu, Daniel La Marra, Philipp Azzarello, Valentina Gallo, Giovanni Ambrosi, Andrea Nardinocchi

Abstract: The Silicon Tracker (STK) is a detector of the DAMPE satellite to measure the incidence direction of high energy cosmic ray. It consists of 6 X-Y double layers of silicon micro-strip detectors with 73,728 readout channels. It's a great challenge to readout the channels and process the huge volume of data in the critical space environment. 1152 Application Specific Integrated Circuits (ASIC) and 38… ▽ More The Silicon Tracker (STK) is a detector of the DAMPE satellite to measure the incidence direction of high energy cosmic ray. It consists of 6 X-Y double layers of silicon micro-strip detectors with 73,728 readout channels. It's a great challenge to readout the channels and process the huge volume of data in the critical space environment. 1152 Application Specific Integrated Circuits (ASIC) and 384 ADCs are adopted to readout the detector channels. The 192 Tracker Front-end Hybrid (TFH) modules and 8 identical Tracker Readout Board (TRB) modules are designed to control and digitalize the front signals. In this paper, the design of the readout electronics for STK and its performance will be presented in detail. △ Less

Submitted 16 June, 2016; originally announced June 2016.

Comments: 10 pages, 17 figures

DAMPE silicon tracker on-board data compression algorithm

Authors: Yifan Dong, Fei Zhang, Rui Qiao, Wenxi Peng, Ruirui Fan, Ke Gong, Di Wu, Huanyu Wang

Abstract: The Dark Matter Particle Explorer (DAMPE) is an upcoming scientific satellite mission for high energy gamma-ray, electron and cosmic rays detection. The silicon tracker (STK) is a sub detector of the DAMPE payload with an excellent position resolution (readout pitch of 242um), which measures the incident direction of particles, as well as charge. The STK consists 12 layers of Silicon Micro-strip D… ▽ More The Dark Matter Particle Explorer (DAMPE) is an upcoming scientific satellite mission for high energy gamma-ray, electron and cosmic rays detection. The silicon tracker (STK) is a sub detector of the DAMPE payload with an excellent position resolution (readout pitch of 242um), which measures the incident direction of particles, as well as charge. The STK consists 12 layers of Silicon Micro-strip Detector (SMD), equivalent to a total silicon area of 6.5m$^2$. The total readout channels of the STK are 73728, which leads to a huge amount of raw data to be dealt. In this paper, we focus on the on-board data compression algorithm and procedure in the STK, which was initially verified by cosmic-ray measurements. △ Less

Submitted 2 March, 2015; originally announced March 2015.

Mapping of dissipative particle dynamics in fluctuating hydrodynamics simulations

Authors: R. Qiao, P. He

Abstract: Dissipative particle dynamics (DPD) is a novel particle method for mesoscale modeling of complex fluids. DPD particles are often thought to represent packets of real atoms, and the physical scale probed in DPD models are determined by the mapping of DPD variables to the corresponding physical quantities. However, the non-uniqueness of such mapping has led to difficulties in setting up simulation… ▽ More Dissipative particle dynamics (DPD) is a novel particle method for mesoscale modeling of complex fluids. DPD particles are often thought to represent packets of real atoms, and the physical scale probed in DPD models are determined by the mapping of DPD variables to the corresponding physical quantities. However, the non-uniqueness of such mapping has led to difficulties in setting up simulations to mimic real systems and in interpreting results. For modeling transport phenomena where thermal fluctuations are important (e.g., fluctuating hydrodynamics), an area particularly suited for DPD method, we propose that DPD fluid particles should be viewed as only 1) to provide a medium in which the momentum and energy are transferred according to the hydrodynamic laws and 2) to provide objects immersed in the DPD fluids the proper random "kicks" such that these objects exhibit correct fluctuation behaviors at the macroscopic scale. We show that, in such a case, the choice of system temperature and mapping of DPD scales to physical scales are uniquely determined by the level of coarse-graining and properties of DPD fluids. We also verified that DPD simulation can reproduce the macroscopic effects of thermal fluctuation in particulate suspension by showing that the Brownian diffusion of solid particles can be computed in DPD simulations with good accuracy. △ Less

Submitted 15 January, 2008; originally announced January 2008.

Journal ref: J. Chem. Phys., 128, 126101, 2008