Study on Fragment Production by Protons and Neutrons and its Effects to the Materials and Living Bodies

半导体器件的软误差和硬误差是现代信息社会中较为严重的问题。为了解决这一问题，我们开展了以下工作：(1)开发了测量10 MeV核子破片产生截面的实验技术；(2)获取了重要核素的系统实验数据；(3)评估了破片产生的理论模型及其对材料和生物的影响。对于碎片测量，我们采用了1)Bragg曲线计数器（BCC）和2)能量tof （E-TOF法），并在信噪比、动态范围和效率方面对该方法进行了改进，实现了对质子和中子碎片的测量。通过采用新的阳极-阴极时差信息，降低碎片识别的阈值能量，从而将脉冲高度范围扩大到原来的两倍左右，并开发了一种估算穿透BCC敏感体积的碎片原始能量的方法。通过同心圆分段阳极的BCC的开发，以及相应的碎片识别和背景还原的改进，中子数据得到了升级。对于BCC技术难以测量的低能粒子，我们构建并采用了采用微通道板和半导体探测器的E-TOF光谱仪。利用研制的装置，我们对70 MeV质子和65 MeV中子的破片产生进行了测量。从氦到氧，中子在0度，质子在30度，60度，90度，135度时得到了碎片数据。我们将我们的实验碎片光谱与理论计算和碎片产生的评估进行了比较，以评估其有效性和问题。总体而言，模型与实验存在严重偏差，有待进一步改进。少

Soft errors and hard errors of semiconductor devices by radiations are of serious problems in mode information society. To trace the problem, we carried out the followings : (1) Development of experimental technique to measure the fragment production cross sections for ten's of MeV nucleons, (2) acquisition of systematic experimental data of important nuclides, and (3) evaluation of theoretical models for fragment production and its influence on the materials and living bodies.1. For fragment measurement, we adopted 1) a Bragg curve Counter (BCC) and 2) energy-TOF(E-TOF method), and realized the measurement of fragments for protons and neutrons by improving the method with respect to signal-to-noise ratio, dynamic range and efficiency. The neutron induced-fragment production data is the first one in the world We extended the pulse-height range up to about twice by a)lowering the threshold energy of fragment identification by newly adopting the information on the anode-cathode time-diff … More erence (corresponding to range), and b)developing a method to estimate the original energy of fragment which penetrated the sensitive volume of BCC. The data for neutrons were upgraded by the development of BCC with a segmented anode of concentric circle and according improvement in fragment identification as well as background reduction. For low energy particles which are difficult to measure with the BCC technique, we constructed and adopted an E-TOF spectrometer employing a micro-channel plates and semiconductor detectors.2. Employing devices developed, we conducted measurement of fragment production for 70 MeV protons and 65 MeV neutrons. Fragment data were obtained from helium to oxygen at 0-deg for neutrons and at 30, 60, 90, 135-deg for protons.3. We compared our experimental fragment spectra with theoretical calculations and evaluations for fragment production to evaluate their validities and problems. Generally, the models showed serious disagreement with experiment and should be improved greatly. Less