1. chinaXiv:202305.00279 [pdf]

The study of a neutron spectrum unfolding method based on Particle Swarm Optimization combined with Maximum Likelihood Expectation Maximization

肖鸿飞; 张庆贤; 谭河益; 石斌; 陈军; 程志强; 张建; 杨芮
Subjects: Physics >> Nuclear Physics

Bonner多球谱仪(BBS)求解中子能谱是一个复杂的多维模型，需要使用复杂的优化算法求解第一类Fredholm积分方程。针对极大似然期望最大化(MLEM)算法容易陷入局部最优，粒子群优化(PSO)算法易得到粒子飞行方向和步长不合理，导致迭代无效，影响效率和精度的问题，提出了一种改进的PSO-MLEM算法用于中子能谱展开。利用动态加速因子平衡全局和局部搜索能力，提高算法的收敛速度和精度。首先，采用蒙特卡罗方法对BBS进行模拟，得到BBS的响应函数和计数率。模拟计数率时，采用了国际原子能机构403号技术报告中的4个参考光谱作为蒙特卡罗方法的输入参数。采用PSO-MLEM算法对中子能谱展开，通过展开能谱与参考能谱的差异进行验证。最后，利用BBS对252Cf中子源进行测量，并采用PSO-MLEM算法展开实验中子谱。与最大熵反卷积(MAXED)、PSO和MLEM算法相比，PSO-MLEM算法参数更少，并自动调整动态加速因子以解决局部最优问题。PSO-MLEM算法的收敛速度分别是MLEM和PSO算法的1.4倍和3.1倍。与PSO、MLEM和MAXED算法相比，PSO-MLEM算法的相关系数分别提高了33.1%、33.5%和1.9%，相对平均误差分别降低了98.2%、97.8%和67.4%。

submitted time 2023-05-31 Hits86， Downloads5， Comment 0

2. chinaXiv:202305.00280 [pdf]

Design and Implementation of Accelerator Control Monitoring System

Chao Yuan; Wei Zhang; Tao Ma; Min Yue; Peng-Peng Wang
Comment：This paper has been successfully submitted online and is presently being given full consideration for publication in Nuclear Science and Techniques.
Subjects: Physics >> Nuclear Physics

submitted time 2023-05-31 Hits83， Downloads4， Comment 0

3. chinaXiv:202305.00274 [pdf]

Measurement of 134Xe(n,2n)133m,gXe reaction cross sections in the 14 MeV region with detailed uncertainty quantification

Junhua Luo; Juncheng Liang; Li Jiang; Fei Tuo; Liang Zhou; Long He
Comment：https://doi.org/10.1007/s41365-022-01158-z
Subjects: Physics >> Nuclear Physics

lead-shielded HPGe detector and offline g–ray spectra of the residual product were used to measure the cross-section (CS) and ratios of isomeric CS (sm/sg) in 134Xe(n,2n)133m,gXe reactions at different energies including 13.5, 13.8, 14.1, 14.4, and 14.8 MeV, relative to 93Nb(n,2n)92mNb reaction CS. The target was high-purity natural Xe gas under high pressure. T(d,n)4He reaction was used to produce neutrons. The TALYS code (1.95 version) for nuclear reactions was used for calculations along with the default parameters and various nuclear level density models. The uncertainties present in the measured CS data were thoroughly analyzed using the covariance analysis method. The results were subsequently compared to the theoretical values, evaluation data, and previous experimental findings. Thus, the CS data of the 134Xe(n,2n)133mXe and 134Xe(n,2n)133gXe reactions and the corresponding isomeric CS ratios at 13.5,13.8 and 14.1 MeV neutron energies are reported for the first time. This work advances our knowledge of pre-equilibrium emission in the (n,2n) reaction channel by resolving inconsistencies in Xe data.

submitted time 2023-05-31 Hits100， Downloads10， Comment 0

4. chinaXiv:202305.00271 [pdf]

Influence of quadrupole deformation and continuum effects on the exotic properties of 15,17,19B with the complex momentum representation method

Cao, Xueneng ; Zhou, Xianxian ; Fu, Ming; Shi, Xinxing
Subjects: Physics >> Nuclear Physics

The properties of exotic nuclei are the focus of the present research. Two-neutron halo structures of neutron-rich 17,19B were experimentally confirmed. We studied the formation mechanism of halo phenomena in 17, 19B using the complex momentum representation method applied to deformation and continuum coupling. By examining the evolution of the weakly bound and resonant levels near the Fermi surface, s–d orbital reversals and certain prolate deformations were observed. In addition, by analyzing the evolution of the occupation probabilities and density distributions occupied by valence neutrons, we found that the ground state of 15B did not exhibit a halo, and the ground states of 17B and 19B exhibited halos at 0.6≤β2≤0.7 and 0.3≤β2≤0.7, respectively. The low-l components in the valence levels that are weakly bound or embedded in the continuous spectrum lead to halo formation.

submitted time 2023-05-31 Hits89， Downloads6， Comment 0

5. chinaXiv:202305.00224 [pdf]

用三轴干涉仪探测引力波的原理和方法

汤克云
Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

LIGO和VIRGO已经测量到几例引力波，这是历史性的重要突破。但是，干涉仪的两条光臂限于地平面内，难于获取引力波的质量源在三维空间的位置。本文提出一种三维探测方案，用三维空间的三轴干涉仪探测引力波及其质量源。本文导出了三轴干涉仪的干涉方程，给出了探测引力波的新原理；据此方程，可以确定激发引力波的质量源的速度和质量源在天球上的坐标，这对于研究引力波的激发和传播的全过程，具有重要意义。

submitted time 2023-05-25 Hits115， Downloads7， Comment 0

6. chinaXiv:202305.00162 [pdf]

Photonuclear production of nuclear isomers using bremsstrahlung induced by laser-wakefield electrons

Lan Haoyang; Wu Di; Liu Jiaxin; Zhang Jianyao; Lu Huangang; Lv Jianfeng; Wu Xuezhi; Luo Wen; Yan Xueqing
Subjects: Physics >> Nuclear Physics

In this study, we theoretically investigate the feasibility of using laser-wakefield accelerated (LWFA) electrons for the photonuclear measurement of nuclear isomers according to the characteristics of the electrons obtained from LWFA experiments conducted at the Compact Laser Plasma Accelerator (CLAPA) laboratory. The experiments at the CLAPA show that a stable electron beam with an energy of 78–135 MeV and a charge of 300-600 pC can be obtained. The bremsstrahlung spectra were simulated using Geant4, which suggests that a bremsstrahlung source with a peak intensity of 1019 photons/s can be generated. Theoretical calculations of isomer production cross-sections from the photonuclear reactions on six target nuclei, 197Au, 180Hf, 159Tb, 115In, 103Rh, and 90Zr were performed and compared with the available experimental data in EXFOR, which suggest that further experiments are required for a series of photonuclear reaction channels. Flux-averaged cross-sections and isomer ratios (IR) resulting from such bremsstrahlung sources are theoretically deduced. The results suggest that IR measurements can be used to constrain nuclear components, such as γ strength function and optical model potential. In addition, the detection of the decay characteristics was evaluated with Geant4 simulations. The use of the LWFA electron beam and its bremsstrahlung for photonuclear studies involving nuclear isomers is anticipated.

submitted time 2023-05-23 Hits268， Downloads40， Comment 0

7. chinaXiv:202304.00973 [pdf]

Integral representation of von Neumann entropy

He, Rui
Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

By using an integral formula, we easily calculated the von Neumann entropy of any quantum state.

submitted time 2023-05-20 Hits409， Downloads120， Comment 0

8. chinaXiv:202305.00159 [pdf]

Decay of superheavy nuclei based on the random forest algorithm

CAI, Boshuai; YUAN, Cenxi
Subjects: Physics >> Nuclear Physics

How nuclides decay in the superheavy region is key information for investigating new elements beyond oganesson and the island of stability. The Random Forest algorithm is applied to study the competition between different decay modes in the superheavy region, including α decay, β− decay, β+ decay, electron capture and spontaneous fission. The observed half-lives and dominant decay mode are well reproduced. The dominant decay mode of 96.9 % nuclei beyond 212Po is correctly described. α decay is predicted to be the dominant decay mode for isotopes in new elements Z = 119 − 122, except for spontaneous fission in some even-even ones because of the increased Coulomb repulsion and odd-even effect. The predicted half-lives show the existence of a long-lived spontaneous fission island at the southwest of 298Fl caused by the competition of nuclear deformation and Coulomb repulsion. More understanding of spontaneous fission, especially beyond 286Fl, is crucial to search for new elements and the island of stability.

submitted time 2023-05-19 Hits280， Downloads52， Comment 0

9. chinaXiv:202305.00155 [pdf]

Spectroscopic factors of resonance states with the Gamow shell model

M. R. Xie; J, G. Li; N Michel; H. H. Li; W. Zuo
Comment：submitted to Physics Review C
Subjects: Physics >> Nuclear Physics

We provide an investigation of the spectroscopic factors of resonance states in $A =5-8$ nuclei using two distinct nuclear models, the Gamow shell model (GSM) and the no-core shell model (NCSM). Configuration mixing is treated exactly in both GSM and NCSM. GSM employs the complex-energy Berggren ensemble, which treats bound, unbound resonance, and non-resonant continuum single-particle states on an equal footing. As a result, continuum coupling is taken into account in GSM, whereas it is absent in NCSM, where the harmonic oscillator basis is used. We first calculate low-lying states of helium isotopes and isotones. The results indicate that GSM can more accurately reproduce the low-lying resonance states than NCSM.  The spectroscopic factors of the resonance states are also computed. Results from the GSM and NCSM are compared and show that continuum coupling plays an important role in the calculations of spectroscopic factors of resonance states. Overlap functions related to the resonance states are also systematically calculated by the GSM and NCSM. It is then demonstrated that wave function asymptotes can only be reproduced in GSM, where continuum coupling is taken into account.

submitted time 2023-05-19 Hits263， Downloads36， Comment 0

10. chinaXiv:202305.00157 [pdf]

LIGO观测到光程差证明了推迟引力波是各向异性的

汤克云
Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

2015年，LIGO探测到第一例引力波，这是百年探索的重大突破。对于干涉仪记录到的光程差，主流物理界的解释是：由于四极矩的偏振特性，分别拉伸和压缩了迈克尔逊干涉仪的两条光臂，产生了不同的形变，从而产生了光程差。本文给出不同的理解：我们已经证明：运动源电荷发出的电磁波是各向异性的，沿不同方向传播的速度有差别。 将这一思路推广到引力波，便得到自然的推论：运动质量源发出的推迟引力波是各向异性的，沿不同方向传播的速度有差别，从而产生了波程差。这种物理图像自然而清晰，似应更合理。

submitted time 2023-05-18 Hits245， Downloads34， Comment 0