分类： 物理学 >> 基本粒子与场物理学 分类： 物理学 >> 核物理学 分类： 物理学 >> 交叉学科物理及相关领域的科学与技术 提交时间： 2024-12-24
摘要： Cerenkov detector has its advantage to construct the reaction vertex and incident direction of the energetic particles, and thus to locate the emission source. We propose to measure the neutrino source by modular photomultiplier tube (PMT) array using clean and transparent deep sea water as sensitive medium. The feasibility of the detection of solar neutrino is demonstrated by full simulation based on Geant4 packages. The production and transport of Cerenkov photons generated by the neutrino electron scattering are simulated. Houth transform method is applied to reconstruct the vertex and the direction of the high-speed electron, as well as the incident direction of the neutrinos. The dominant background of gamma radiation from 40K in sea water can be suppressed by a factor of 10^7 if a threshold on the number of firing PMTs is introduced. The total reconstruction efficiency increases with the incident energy, reaching 25% for 6 MeV neutrino and 52% for 10 MeV neutrino, respectively. To locate an existing neutrino source, a certain number of neutrino events are required, depending on the background intensity above the threshold. The simulation results reveal how feasible to measure solar neutrino using deep sea water.
分类： 物理学 >> 核物理学 提交时间： 2023-12-29
Dawei Si
Yan Zhou
Sheng Xiao
Zhi Qin
Dong Guo
Yuhao Qin
Yijie Wang
Boyuan Zhang
Baiting Tian
Zhigang Xiao
摘要： The energetic bremsstrahlung photons up to 100 MeV produced in heavy ion collisions can be used as asensitive probe to the short range correlation in atomic nuclei. The energy of the -rays can be measuredby collecting theˇCerenkov light in medium induced by the fast electrons generated in Compton scattering orelectromagnetic shower of the incident ray. Two types of detectors, based on pure water and lead glass asthe sensitive material respectively, are designed for the above purpose. The response and optical photonpropagation in detectors have been simulated based on the electromagnetic and optical processes in Geant4.The inherent energy resolution of 0.022(4) + 0.51(2)/E 1/2 for water and 0.0026(3) + 0.446(3)/E 1/2 forlead glass are obtained. The geometry size of lead glass and water are optimized at 30 30 30 cm3 and60 60 120 cm3 , respectively, for detecting high energy -rays at 160 MeV. Hough transform method hasbeen applied to reconstruct the direction of the incident -rays, giving the ability to distinguish experimentallythe high-energy rays produced in the reactions on the target from the random background cosmic ray muons.
分类： 物理学 >> 核物理学 提交时间： 2023-09-11
Guo, Dong
Haoqian Xyu
DongDong Qi
HeXiang Wang
Lei Zhang
Zhengyang Sun
Zhi Qin
Botan Wang
Yingjie Zhou
Zekun Wang
Yuansheng Yang
Yuhao Qin
Xianglun Wei
Herun Yang
Yuhong Yu
Lei Zhao
Zhigang Xiao
摘要： A trigger system has been designed and implemented for the HIRFL-CSR external target experiment (CEE), the spectrometer for studying nuclear matter properties with heavy ion collisions in the GeV energy region. The system adopts master-slave structure and serial data transmission mode using optical fiber to deal with different types of detectors and long-distance signal transmission. The trigger logic can be accessed based on command register and controlled by a remote computer. The overall field programmable gate array (FPGA) logic can be flexibly reconfigured online to match the physical requirements of the experiment. The trigger system has been tested in beam experiment. It is demonstrated that the trigger system functions correctly and meets the physical requirements of CEE.
分类： 核科学技术 >> 辐射物理与技术 提交时间： 2024-12-13
Zhi Qin
Zhoubo He
Zhe Cao
Tao Chen
Zhi Deng
Limin Duan
Dong Guo
Rongjiang Hu
Jie Kong
Canwen Liu
Peng Ma
Xianglun Wei
Shihai Wen
Xiangjie Wen
Junwei Yan
Herun Yang
Zuoqiao Yang
Yuhong Yu
Zhigang Xiao
Tian-Lei Pu
摘要： The half-size prototype of the multi wire drift chamber (MWDC) for the cooling storage ring (CSR) external-target experiment (CEE) was assembled and tested in 350 MeV/u Kr+Fe reactions on the heavy ion research facility in Lanzhou (HIRFL). The prototype consists of 6 sense layers, where the sense wires are stretched in three directions X, U and V, meeting 0^\circ, 30^\circ and -30^\circ with respect to the vertical axis, respectively. The sensitive area of the prototype is 76 {\rm cm} \times 76 {\rm cm}. The amplified and shaped signals from the anode wires are digitized in a serial capacity array. Being operated with 1500 V high voltage on the anode wires, the efficiency for each layer is beyond 95\%. The tracking residual is about 301 \pm 2 \rm \mu m. The performance meets the requirements of CEE.
分类： 物理学 >> 核物理学 提交时间： 2025-01-17
Dawei Si
Sheng Xiao
Zhi Qin
Junhuai Xu
Baiting Tian
Boyuan Zhang
Haojie Zhang
Dong Guo
Yijie Wang
Xiaobao Wei
Yibo Hao
Zengxiang Wang
Tianren Zhuo
Chunwang Ma
Yuansheng Yang
Xianglun Wei
Herun Yang
Peng Ma
Limin Duan
Fangfang Duan
摘要： The neutron-neutron (nn) correlation function has been measured in 25 MeV/u ^{124}Sn+^{124}Sn reactions.Using the Lednick\’y-Lyuboshitz approach, the nn scattering length and effective range (f_{0}^{nn}, d_{0}^{nn}), as well as the reduced space-time size R^{(0)} of the neutron emission source are simultaneously extracted as (18.9^{+1.3}_{-1.2} fm, 1.9^{+1.3}_{1.0} fm) and 4.12 \pm 0.12 fm, respectively. The measured nn scattering length is consistent with the results obtained in the low-energy scattering ^{2}{\rm H}(\pi^{-},\gamma)2n, indicating heavy-ion collisionscan serve as an effective approach for measuring nn interactions and further investigating the charge symmetry breaking of nuclear force. The space-time size extracted from momentum-gated correlation functions exhibits clear dependence on the pair momentum, with R^{(0)}=2.8 \pm 0.1 fm and 4.9 \pm 0.2 fm being determined for the high and low momentum neutrons, respectively.
分类： 物理学 >> 核物理学 提交时间： 2025-04-20
Junhuai Xu
Qinglin Niu
Yuhao Qin
Dawei Si
Yijie Wang
Sheng Xiao
Baiting Tian
Zhi Qin
Haojie Zhang
Boyuan Zhang
Dong Guo
Minxue Fu
Xiaobao Wei
Yibo Hao
Zengxiang Wang
Tianren Zhuo
Chunwang Ma
Yuansheng Yang
Xianglun Wei
Herun Yang
摘要： The nucleons in nuclei form temporally correlated pairs in close proximity, called short range correlation (SRC), which plays a crucial role in understanding nuclear structure and the fundamental properties of dense nuclear matter. The consequence of SRC on heavy-ion collisions (HICs) has remained unexplored until now. In this paper, we identify neutron-proton bremsstrahlung γ-ray emission from HICs as a new indicator of SRC in nuclei. By observing the hardening of the bremsstrahlung γ-ray spectrum, which results from the increase of high-momentum components above the Fermi surface in nucleon momentum distributions, we precisely determine the SRC fraction in nuclei to be (21±7)% at 3σ confidence levels. Our experiment identifies the first direct and accurate signature of SRC in low-energy HICs, providing a new method to study the parton momentum distribution of nucleons in nuclei.
分类： 物理学 >> 核物理学 提交时间： 2023-11-25
Yijie Wang
Fenhai Guan
Qianghua Wu
Xinyue Diao
Yan Huang
Liming Lyu
Yuhao Qin
Zhi Qin
Dawei Si
Zhen Bai
Fangfang Duan
Limin Duan
Zhihao Gao
Qiang Hu
Rongjiang Hu
Genming Jin
Shuya Jin
Junbing Ma
Peng Ma
Jiansong Wang
摘要： The intensity interferometry is applied as a chronometer of the particle emission of hydrogen isotopes from the intermediate velocity source formed in ^{40}Ar+^{197}Au reactions at 30 MeV/u. The dynamic emission order of tau_{ rm p}> tau_{ rm d}> tau_{ rm t} is evidenced via the correlation functions of nonidentical particle pairs. Assuming the similar source size, the same emission order is inferred from the correlation functions of identical particle pairs, where tau_{ rm p} approx 100 { rm ~fm/c} is extracted by the fit of Koonin-Pratt equation to p-p correlation function. Transport model simulations demonstrate that the dynamic emission order of light charged particles depends on the stiffness of the nuclear symmetry energy.
分类： 物理学 >> 核物理学 提交时间： 2023-11-15
Yijie Wang
Mengting Wan
Xinyue Diao
Sheng Xiao
Yuhao Qin
Zhi Qin
Dong Guo
Dawei Si
Boyuan Zhang
Baiting Tian
Fenhai Guan
Qianghua Wu
Xianglun Wei
Herun Yang
Peng Ma
Rongjiang Hu
Limin Duan
Fangfang Duan
Junbing Ma
Shiwei Xu
摘要： The neutron rich neck zone created in heavy ion reaction is experimentally probed by the production of the A=3 isobars. The energy spectra and angular distributions of triton and ^3He are measured with the CSHINE detector in ^{86}Kr +^{208}Pb reactions at 25 MeV/u. While the energy spectrum of ^{3}He is harder than that of triton, known as ^{3}He-puzzle, the yield ratio R({ rm t/^3He}) presents a robust rising trend with the polar angle in laboratory. Using the fission fragments to reconstruct the fission plane, the enhancement of out-plane R({ rm t/^3He}) is confirmed in comparison to the in-plane ratios. Transport model simulations reproduce qualitatively the experimental trends, but the quantitative agreement is not achieved. The results demonstrate that a neutron rich neck zone is formed in the reactions. Further studies are called for to understand the clustering and the isospin dynamics related to neck formation.
分类： 物理学 >> 核物理学 提交时间： 2023-11-14
Yijie Wang
Fenhai Guan
Dawei Si
Sheng Xiao
Boyuan Zhang
Yaopeng Zhang
Baiting Tian
Xianglun Wei
Herun Yang
Peng Ma
Rongjiang Hu
Limin Duan
Fangfang Duan
Qiang Hu
Junbing Ma
Shiwei Xu
Zhen Bai
Yanyun Yang
Jiansong Wang
Wenbo Liu
摘要： Two-body correlations of the isotope-resolved light and heavy clusters are measured in 86Kr+ 208Pb reactions at 25 MeV/u. The yield and kinetic variables of the A = 3 isobars, triton and 3He, are analyzed in coincidence with the heavy clusters of 7 A 14 emitted at the earlier chance. While the velocity spectra of both triton and 3He exhibit scaling behavior over the type of the heavy clusters, the yield ratios of t/ 3He correlate reversely to the neutron-to-proton ratio N/Z of the latter, showing the ping-pong modality of the N/Z of emitted clusters. The commonality that the N/Z of the residues keeps the initial system value is extended to the cluster emission in heavy ion reactions. The comparison of transport model calculations to the data is discussed.
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