25MeV/u 6He+9Be破裂反应的α碎片发射

测量了在25MeV/u 6 He轰击9Be靶的破裂反应产生的α碎片双微分截面及角分布,并在Serber模型的框架下计算了在破裂反应中衍射破裂与擦去过程的贡献,并对结果进行了讨论. 结果表明基于包含衍射破裂和擦去过程的Serber模型可以对6He的直接反应进行较好地描述,擦去过程的贡献远大于衍射破裂的贡献. 相对于6Li而言,6He较大的去2n微分截面源于它的弱束缚特性.     

Iosotopic Distributions of the ^18N Fragmentation Products in Coincidence with Neutrons on Targets ^197Au and ^9Be

We present the experimental isotopic distributions of the ^18N projectile fragmentation products Li,Be,B and C in coincidence with neutrons,as well as the inclusive ones on ^197Au and ^9Be targets.In the framework of the abrasion-ablation model,these distributions are calculated for various nucleon density distributions of the projectile.The comparison with experimental isotopic distributions of the projectile-like fragments in coincidence with neutrons shows that the information on the nucleon density distribution of the ^18N projectile can be extracted.     

Efficiency calibration of neutron detector array for β decay of exotic nuclei

The research of the in-beam efficiency calibration of Neutron Detector Array of Peking University using ¹⁷N and ¹⁶C beams was introduced in this paper. The efficiency of neutron wall and ball are comparable to the foreign similar devices and neutrons can be detected from low to high energies in high efficiency.     

Characteristics of a 4-fold segmented clover detectore

Four high-purity germanium 4-fold segmented Clover detectors have been applied in the experiment of neutron-rich nucleus 21N. The performance of those four Clovers have been tested with radioactive sources and in-beam experiments, and the main results including energy resolution, peak-to-total ratios, the variation of the hit pattern distribution in different crystals of one Clover detector with the energy of γ ray, and absolute full energy peak detection effciency curve, were presented.     

Measurement of the Breakup Cross Sections in ^6He＋^9Be Reaction at 25 MeV／Nucleon

The breakup reaction cross sections were measured for the reaction of^6He at 25 MeV/nucleon from ^9Be target with intensity of 10^5 pps. By fitting the energy spectra of breakup α particles with Gaussian functions, the angular distribution of differential cross sections in the laboratory system has been extracted and compared with the Serber model calculations. The good agreement between the calculation and the experimental data favours a dominant configuration of the ^4He core plus valence neutrons for the structure of^6He.     

晕核6He（25 MeV/u）在9Be上的破裂反应

25 MeV/u 6He+9Be反应的实验中利用多个探测器望远镜对反应产物进行了测量, 对实验中各个角度测量到的4He进行观察, 将其中两个有高能峰成分的探测器划分成三部分, 得到不同角度4He的单举能谱和破裂产生4He的微分截面. Different products of 6He nuclei from 9Be target has been measured with a 6He beam at energy of 25 MeV/u. The energy spectra at different angles for 4He isotope were analyzed and the experiment differential cross sections for the direct breakup reaction were obtained.     

二维位置灵敏硅探测器的应用研究

对二维位置灵敏硅探测器进行了239Puα源刻度测试,并在弹性散射实验中使用了二维位置灵敏硅探测器.考察了两种定位方法在实验中与测试中的一致性.测量了二维位置灵敏硅探测器的能量分辨率、位置分辨率和位置畸变.对位置畸变进行了定性理论解释.     

透射法测量丰中子核8He的去中子截面

利用HIRFL提供的50MeV/u ¹³C束流轰击Be靶, 通过RIBLL选择出丰中子放射性核⁸He. 利用透射法测量了⁸He的去双中子截面和去四中子截面. 利用Ogawa等人的理论结合原有⁸He的反应总截面数据, 得到⁸He的核芯为⁴He的结论.     

中能区丰中子核11Li的反应总截面的测量

利用HIRFL提供的50MeV/u的¹³C束流轰击Be靶, 通过RIBLL选择出放射性核素¹¹Li. 实验采用透射法测量了25—45MeV/u的¹¹Li在²⁸Si靶上的反应总截面. 采用双参数Gauss密度分布形式, 利用Glauber模型很好地拟合了高能和中能区的¹¹Li实验数据, 并从密度分布中提取了核的物质均方根半径.     

RIBLL上的β+缓发粒子发射的在束测量

报道了在新建成的放射性次级束流线上完成的²⁰Na的β+缓发α粒子发射²⁰Na—→β^+　20Ne→¹⁶O+α的在束测量.通过飞行时间和能损符合的方法实现²⁰Na次级束流的在束鉴别与调制.在束和停束两个获取时段分别完成对次级束流和β+缓发粒子的记录.利用脉冲发生器和记数器实现²⁰Na缓发粒子衰变半衰期的测量.实验测量到²⁰Ne几个低能共振能级的衰变能量分别为2.69,3.09,4.74,5.54MeV,相对强度分别为100,4.15,1.10,15.20.测量到²⁰Na的β⁺缓发α衰变的半衰期为(459±7)ms,与现有的核数据基本上吻合.