氘核削裂反应理论研究及其进展

氘核削裂反应作为单核子转移反应的一种,在原子核的单粒子结构研究中一直起着重要的作用。同时,作为典型的三体核反应,它也是直接核反应理论研究的一个重要研究对象。本文简述了氘核削裂反应的研究历史,侧重介绍其反应理论的演进,以及平面波玻恩近似(Plane Wave Born Approximation,PWBA)、扭曲波玻恩近似(Distorted Wave Born Approximation,DWBA)、连续态离散化耦合道理论(Continuum Discretized Coupled Channels,CDCC)、绝热波近似理论(Adiabatic Wave Approximation,ADWA)和法捷耶夫方程组(Faddeev equations)方法之间的差别与联系。本文讨论了当前及未来氘核削裂反应理论研究的若干热点问题,包括中高能条件下的氘核削裂反应、转移到剩余核连续态的理论、色散光学势以及非定域光学势在氘核削裂反应中的应用等。本文展示了我们对中高能条件下的氘核削裂反应理论计算的一些初步成果。     

Study of fusion Q-value rule in sub-barrier fusion of heavy ions

A vast body of fusion data has been analyzed for different projectiles and target nuclei. It is indicated that the sub-barrier fusion depends on the fusion Q-value. In terms of a recently introduced fusion Q-value rule and an energy scaling reduction procedure, the experimental fusion excitation functions are reduced and compared with each other. It is found that the reduced fusion excitations of selected fusion systems show a similar trend. The fusion data for massive nuclei are in agreement with the Q-value rule. In the fusion process, the Q contribution should be considered. Within this approach, the sub-barrier fusion cross sections of most fusion systems can be predicted without involving any structure effects of colliding nuclei. Instances of disagreement are presented in a few fusion systems. The use of the energy scaling as a criterion of possible experimental data inconsistency is discussed. More precise experimental fusion data need to be measured.     

验证辐射强度与距离平方反比率的实验

利用Nal闪烁谱仪测量了在探测器与放射源间某个距离下对应的计数率.对测量的数据分别利用等精度最小二乘法和未知参数逼近法进行了处理,观察到在某些未知参数下,最小二乘法引起的误差很大,利用未知参数逼近法得到的值能和真实值较好接近,从而验证了辐射强度与距离平方反比率.     

肖特基结的制备与势垒测量

采用磁控溅射方法在Nb07％-SrTiO3基片上制作Au薄膜接触,并在氧气气氛下750℃退火30 min,在室温环境下测量电流电压和电容电压等特性曲线,观测整流特性,根据相应实验数据采用饱和电流法、电容C-2与反偏电压V成线性关系计算肖特基势垒的大小.     

硅探测器的数字化脉冲形状甄别

介绍了利用硅探测器的脉冲形状甄别进行粒子鉴别的原理。详细叙述了基于数字化方法的脉冲形状甄别的实现。采样频率和位数是数字化方法的两个重要参数。对于硅探测器信号,采用100 MS/s,12 bit的Digitizer可以满足脉冲形状甄别法对时间分辨的要求。同时对该方法粒子鉴别的特征和能量阈值做了简要的分析和对比。粒子背面入射硅探测器的所得的阈值低于正面入射的情况。例如对于氖周围的同位素,背面入射情况的阈值约为100 MeV,为正面入射情况下鉴别阈值的二分之一,相当与ΔE-E方法中ΔE探测器厚度约为60 μm情况下的阈值。最后定性讨论了硅探测器的电阻率不均匀性和沟道效应对粒子鉴别性能的影响。In this paper Pulse Shape Discrimination(PSD) for silicon detector has been briefly introduced. The emerging digital method successfully applied to detector signal processing makes digital PSD method one of the most promising particle identification methods. Sampling frequency and the number of bits are two key parameters of digital method. For silicon detector signal, adopting 100 Ms/s, 12 bit Digitizer can satisfy the time resolution requirement of PSD method. The identification characteristic and energy threshold of this method have been discussed and compared with both front injection and rear injection cases. Energy threshold with rear injection usually is much lower than that with front injection. For example, around for Neon isotope energy threshold with rear injection is about 100 MeV which is only half of the threshold with front injection, also equivalent to thickness of about 60 μm silicon detector threshold in ΔE-E method. At the end the impact of silicon detector's resistivity nonuniformity and channel effect on the identification capacity of PSD method has been discussed in detail.     

质子滴线核8B的实验研究进展

质子滴线核8B的最后一个质子的分离能只有0.137 5 MeV,被认为是最有可能具有质子晕结构的候选核之一,对其反应机制和奇特结构的研究吸引了人们的关注。针对8B的奇特结构和反应机制研究是一个非常有趣的课题,研究人员在包括反应截面、碎裂产物动量分布宽度、电四极矩、熔合截面及弹性散射等方面开展了大量的工作。但是8B的研究至今仍不够充分,需要从理论和实验上对其进行更深入的研究。     

β-delayed neutron decay of 21N

The β-delayed neutron and γ spectra of neutron-rich nucleus ²¹N using β-γ and β-n coincidence measurements were presented in this paper. Thirteen new neutron groups ranging from 0.28 MeV to 4.98 MeV and with a total branching ratio 88.7±4.2% were observed. One γ transition among the excited states of ²¹O, and four γ transitions among the excited states of ²⁰O were identified in the β decay chain of ²¹N. The ungated half-life of 83.8±2.1 ms was also determined for ²¹N.     

Proton Spectroscopic Factors Deduced from Helium-3 Global Phenomenological and Microscopic Optical Model Potentials

Global phenomenological GDP08 and microscopic hefium-3 optical model potentials have been recently derived. We evaluate these two potential sets by comparing the elastic scattering data of 25 MeV 3He on 160, 180, 19F, 23Na, 24Mg, 25Mg, 26Mg, 27A1, 28Si, 30Si, 31p, 32S, 34S, 35Cl, 3761, and 39K isotopes. Using the deuteron angular distributions calculated with the distorted wave Born approximation model, we extract the ground-state proton spectroscopic factors from （3He, d） reactions on the same set of nuclei. The extracted proton spectroscopic factors are compared with the large-basis shell-model calculations.     

β缓发中子探测阵列的性能优化及测试

讲述了用于β缓发中子发射测量的中子探测阵列的性能优化过程及测试结果. 对中子探测器包装用的几种反射材料、光导和光电倍增管之间用的几种耦合材料行了系统的对比和研究. 为了优化电子学和实时监测整个探测阵列的工作状态, 引入了LED光纤刻度监测系统.