14.8MeV中子诱发^(78)Kr(n,2n)^(77)Kr反应截面的测量  

Measurement of ^(78)Kr(n,2n)^(77)Kr Reaction Cross Section Induced by 14.8 MeV Neutron

作　　者：梁建峰[1] 解峰[1] 阮锡超[2] 鲍杰[2] 陈雄军[2] 师全林[1] 李雪松[1] 余功硕[1] 康泰 LIANG Jianfeng;XIE Feng;RUAN Xichao;BAO Jie;CHEN Xiongjun;SHI Quanlin;LI Xuesong;YU Gongshuo;KANG Tai(Northwest Institute of Nuclear Technology,Xi’an 710024,China;China Nuclear Data Center,Key Laboratory of Nuclear Data,China Institute of Atomic Energy,Beijing 102413,China)

机构地区：[1]西北核技术研究所,陕西西安710024 [2]中国原子能科学研究院核数据重点实验室,中国核数据中心,北京102413

出　　处：《原子能科学技术》2022年第5期835-842,共8页Atomic Energy Science and Technology

摘　　要：快中子诱发(n,2n)反应截面的测量在核反应机制研究和核技术应用等方面有着广泛的应用价值。本文在中国原子能科学研究院的高压倍加器上,基于活化法实验测量了^(78)Kr(n,2n)^(77)Kr在14.8 MeV能点的反应截面。样品靶为高纯^(78)Kr气体样品,用十万分之一天平称重得到^(78)Kr的质量,将两片高纯^(93)Nb薄片分别固定在样品靶两侧以监测中子注量率。利用T(d,n)_(4)He反应产生14.8 MeV中子,轰击距中子源约10 cm的样品靶大于4 h后,用准确刻度过效率的HPGe探测器测量活化产物^(77)Kr和^(92)Nb^(m)的活度。利用蒙特卡罗程序计算中子注量率修正、样品自吸收修正、样品几何修正等因子,得到了^(78)Kr(n,2n)^(77)Kr的反应截面,并将结果与文献值和评价数据库进行了比较。研究结果有助于提高^(78)Kr(n,2n)^(77)Kr反应截面测量和评价的水平。The measurement of(n,2n)reaction cross section induced by fast neutron plays an important role in nuclear reaction mechanism research and nuclear technology applications.Experiments have been carried out over the last several decades.However,most experiments focused on solid samples including 89 Y,151 Eu,203 Tl,232 Tl and so on,and there are few reported results about gaseous samples such as xenon and krypton.The 78 Kr(n,2n)77 Kr reaction cross section was poorly studied,and this work aimed to measure the cross section induced by 14.8 MeV neutron.The measurement was performed by the activation method,and the experiment was carried out at the Cockcroft Walton Accelerator of China Institute of Atomic Energy(CIAE).A cell made of PMMA was used as the gas container,and the 78 Kr gas(enriched to 99.5%abundance)was injected into the cell using a syringe.The mass of 78 Kr gas sample was determined by weighing method.Quasi monoenergetic neutron beams with a yield of about 3×1010 s^(-1) were produced via the T(d,n)4He reaction(Q=17.6 MeV).The ion beam current was about 250μA,and the average energy of D+particles was about 300 keV.The neutron flux determination was accomplished by attaching two 93 Nb foils(same diameter as the cell and thickness of 50μm)with purity of 99.99%to the upstream and downstream faces of the cell.The sample was placed at 0°angel relative to the incident D+beam direction and centered about the T-Ti target at a distance of about 10 cm,where the neutron flux was 2×107 cm^(-2)·s^(-1).After irradiation,the activities of 77 Kr and 92 Nb m were measured by off-line gamma-ray spectrometric technique using a pre-calibrated HPGe detector on the surface of the detector end cap due to their low activity.To obtain detection efficiencies,another irradiation experiment was carried out individually to produce 77 Kr and 92 Nb m with high activities,which were used to measure the count rate ratio of the characteristicγ-ray at a distance of 25 cm and on the surface.The efficiencies at the position of 25 cm wer

关 键 词：^(78)Kr(n 2n)^(77)Kr 反应截面 活化法 HPGEΓ谱仪 

分 类 号：O571.4[理学—粒子物理与原子核物理]