## 留言板

2021, (3): 1-2.

2021, 38(3): 229-243.   doi: 10.11804/NuclPhysRev.38.2021046

2021, 38(3): 244-249.   doi: 10.11804/NuclPhysRev.38.2020045

2021, 38(3): 250-255.   doi: 10.11804/NuclPhysRev.38.2021044

Energy level density plays an important role in the study of kinetic and thermodynamic properties of nuclear physics. In this paper, shell model and the truncation algorithm are used to calculate the lowest 10 000 states of Sn isotopes. The number of holes and the number of particles in the $^{116}{\rm{Sn}}$ isotope of Sn is 8, and the energy level is the most complex. According to the $^{116}{\rm{Sn}}$ energy level density, the relationship between energy level density and angular momentum and the microcanonical entropy of the system are studied. It is found that the lowest average energy level under even parity has an obvious odd-even effect of angular momentum, which can be reasonably explained by Pauli exclusion principle. Furthermore, the properties of different Sn isotopes are studied and a similiar conclusion is obtained. The microcanonical entropy of $^{116}{\rm{Sn}}$ is fluctuated by odd parity in the low energy band, which is related to the fracture of neutron pairs.
2021, 38(3): 256-264.   doi: 10.11804/NuclPhysRev.38.2021028

QCD(Quantum Chromo Dynamics)手征反常理论主导了π0介子到两个$\gamma$光子的衰变。基于手征反常理论和手征微扰论的修正，对π0介子寿命的理论预测精度高达1%。高精度实验测量π0介子的寿命可以严格检验低能区的QCD理论和手征微扰论。本工作重点介绍了三种测量π0介子寿命的实验方法：直接测量法、双光子反应法和Primakoff测量法。2018版的PDG收录了测量π0介子寿命精度最高的5个实验，并以此给出π0介子寿命的平均值。回顾了这5个实验，其中2004年在美国JLab实验室进行的PrimEx-I实验的测量精度最高，为2.8%。虽然这些实验结果在误差范围内与理论预测相符合，但实验精度还不足以严格检验精度为1%的理论预测。为了进一步提高实验精度，美国JLab实验室于2010年进行了第二次实验PrimEx-II，测量精度为1.57%。将PrimEx实验系列的结果取加权平均，得到总的实验不确定度为1.50%。这是迄今为止对π0寿命最精确的实验测量，在实验误差范围内可以验证QCD手征反常理论的预测。此外，还对PrimEx-II的设备布局和数据分析方法做了简单介绍。

2021, 38(3): 265-269.   doi: 10.11804/NuclPhysRev.38.2021002

2021, 38(3): 270-276.   doi: 10.11804/NuclPhysRev.38.2021017

Laser ablation plasma(LAP) can be used as an ion source for particle accelerators and for ion implantation. Although the too intensive current intensity of laser ion sources give them advantages over other ion sources, yet the minute duration of laser produced ion pulses limits their applications in accelerators. By introducing a solenoid into the plasma expansion region, the modulation of the plasma temporal structure had been achieved[1-3]. In order to study the effect of solenoid magnetic field on LAP, we used different laser energies (1~8 J) to produce LAP at different initial conditions and applied various magnetic field strengths to confine the plasma. The transverse distribution of the laser produced ions were measured with a movable faraday cup (FC) at the edge of the fringe field of the solenoid. The main parameters of the ion pulses, the total charge, the peak current, and the pulse duration, enhanced at first and then got saturated with the increasing magnetic field, no matter what the initial plasma conditions were. Unlike the nearly uniform transverse distribution of the plasma without magnetic confinement, the plasma got concentrated when the magnetic field was applied. The experimental results presented and discussed in the present work are of great significance for further understanding the characteristics of magnetically confined LAP.
2021, 38(3): 277-282.   doi: 10.11804/NuclPhysRev.38.2020073

2021, 38(3): 283-292.   doi: 10.11804/NuclPhysRev.38.2020071

2021, 38(3): 293-300.   doi: 10.11804/NuclPhysRev.38.2020060

2021, 38(3): 301-310.   doi: 10.11804/NuclPhysRev.38.2020070

2021, 38(3): 311-318.   doi: 10.11804/NuclPhysRev.38.2020067

$\gamma$放射性内污染修正均匀冗余阵列编码成像中，为了进一步减少使用最大似然估计(Maximum Likelihood Expectation Maximisation，MLEM)算法进行编码图像重建的伪影，并且提高重建的效率，本文提出了基于差分曲率的各项异性扩散小波图像降噪(Anisotropic Diffusion Wavelet Image Denoising based on Differential Curvature, 简称ADWIDDC)算法, 结合MLEM算法得到了改进的应用于编码成像的MLEM-ADWIDDC算法。该算法首先采用MLEM算法对探测器得到的投影数据进行图像重建，再利用互补成像方法消减近场伪影，最后采用ADWIDDC算法进一步降低图像伪影。模拟结果表明，对于131I源呈圆环分布的编码图像，以重建算法运行时间为195 s为截止条件，MLEM-ADWIDDC算法能够更好地去除伪影，重建的$\gamma$放射源图像纹理也更加清晰；对于131I源呈“CDUT”分布的编码图像，以重建图像信噪比达到5.10 dB为截止条件，本文的MLEM-ADWIDDC算法运行时间为98.36 s，比仅采用MLEM算法消耗的时间缩短了49%。

2021, 38(3): 319-326.   doi: 10.11804/NuclPhysRev.38.2021006

2021, 38(3): 327-331.   doi: 10.11804/NuclPhysRev.38.2021015

The characteristic of single-event upset(SEU) in a 14-nm bulk fin field-effect transistor (FinFET) static random access memory(SRAM) is investigated by heavy-ion experiments. The linear energy transfer(LET) threshold 0.1 MeV/(mg/cm2) is obtained by fitting the SEU cross-section using the Weibull function. The contribution of multiple-bit upset(MBU) is investigated. The results show that when the LET is equal to 40.3 MeV/(mg/cm2), greater than 95% of SEU comes from the MBU. Additionally, the SEU cross-section of the FinFET SRAM presents anisotropies for incident angles associated with the fin direction. This research has a certain kind of guiding role in designing of radiation-hardened complementary metal-oxide semiconductor(CMOS) integrated circuits(ICs) based on FinFET technology.

2021, 38(3): 332-338.   doi: 10.11804/NuclPhysRev.38.2021013

2021, 38(3): 339-344.   doi: 10.11804/NuclPhysRev.38.2021036

2021, 38(3): 345-354.   doi: 10.11804/NuclPhysRev.38.2021009