Structure change of 156Yb at high-spin states

High-spin states of ¹⁵⁶Yb have been studied via the ¹⁴⁴Sm(¹⁶O,4n)¹⁵⁶Yb fusion-evaporation reaction at beam energy 102~MeV. The positive-parity yrast band and negative-parity cascade have been extended up to higher-spin states, respectively. The characteristics of the negative-parity sequence above the 25^－ state may related to the excitation from the nucleon in the Z=64, N=82 core. The E-GOS curve for the positive-parity yrast sequence in ¹⁵⁶Yb indicate that this nucleus may undergo an evolution from quasivibrational to quasirotational structure with increasing angular momentum. The Cranked Woods-Saxon-Strutinsky calculations by means of Total-Routhian-Surface (TRS) methods has been made to understand this structure change.     

大面积闪烁体探测器的中子探测效率刻度

介绍了一种利用同位素中子源(²⁴¹Am⁹Be)通过γn符合的中子飞行时间法对大面积探测器的中子探测效率进行刻度的方法,并用蒙特卡罗方法对该探测器的探测效率进行了模拟.实验与模拟结果基本一致.     

用GC-MS联用技术鉴定亚磷酸三乙酯中杂质并探讨其合成工艺

亚磷酸三乙酯是一种农药、医药中间体,用于生产农药杀螟威、镇痛药苯噻啶等,也可作为增塑剂、润滑油和润滑脂的添加剂,还是制造TDS等荧光增白剂重要的过渡中间体.工业品为无色透明液体,沸点156.6℃,溶于乙醇、乙醚、丙酮、苯,不溶于水.在水中易水解,在酸性介质中水解加快.通常以无水乙醇与三氯化磷和氨反应制造,以石油醚、三氯乙烯、甲苯、二甲苯等为溶剂,收率70%～75%[1].     

6He中t+t结构的实验研究

在25MeV/u ⁶He轰击⁹Be靶的反应中,用探测器望远镜测得氚碎片,得到了5个角度的能谱,经过仔细的分析取得了高能直接破碎成分的角分布.利用Serber模型进行了破碎反应的理论计算,证实了实验中高能成分的t来自于⁶He的直接破碎反应.利用Fermi破碎模型计算了⁶He中各破碎反应道基于相空间的百分比产额,进而估算出⁶He初态中t+t结构的概率约占1/3, 而⁴He核心加价中子的组态约占2/3.     

晕核6He(25 MeV/u)在9Be上的弹性散射研究

分析了北京大学核物理实验小组在日本RIKEN实验室完成的25 MeV/u 6He和9Be的弹性散射实验数据，得到了弹性散射微分截面角分布. 利用双折叠模型，并通过拟合弹性散射微分截面得到了此弹靶体系在此能量下的弹性散射光学势. We analyzed the 6He elastic scattering from 9Be target at 25 MeV/u. A Center of Beam (CB) method was used to calibrate the particle tracking detectors and set the reference system of the detection system. The double folding model approach was used to calculate the real part of the optical model potential. The preliminary optical model potential parameters were extracted by fitting the experimental differential elastic scattering cross sections.     

核物理与工农业发展

核物理应用主要包括核分析技术、同位素技术和离子束技术的应用,这些应用在工农业生产中发挥着巨大作用.离子束、电子束和同位素辐射源被广泛应用于辐照探伤、辐照加工、辐照消毒、辐照育种、辐照杀虫、辐照保藏等方面.核物理应用新技术将成为人类生活中重要的组成部分,正确认识核辐射并掌握基本的辐射防护知识具有重要意义.文章介绍了核物理在工业和农业中的应用及其社会效益和经济效益.     

Storage and Retrieval of a Weak Optical Signal Improved by Spontaneously Generated Coherence in an Atomic Assemble

We investigate the reversible storage of a weak single-mode light signal in a Λ-type three-level atomic system with spontaneously generated coherence (SGC) and pumped by an incoherent field.The scheme is phase-dependent.If the phase of the controlling field is set oppositely to that of the signal field,the combination of SGC with weak pump overcomes the drawback of incompletely retrieval in the conventional scheme,leading to 100% retrieval fidelity or even to the amplification of the retrieved signal with respect to its initial one.     

Study of the structure of borromean nucleus 17Ne

The ¹⁷Ne nucleus is a possible candidate with a two-proton borromean halo structure. Since the theoretical model is difficult to handle the three-body system, it is difficult to determine the two-proton halo structure in ¹⁷Ne. In the present research, we try to study the breakup reaction of ¹⁷Ne. For the Borromean nuclei, one-proton knockout results in an unstable nucleus which is decaying further by proton emission. This process will result in an angular correlation between the direction of the aligned recoiling unstable nucleus and its decay products. The angular correlations can give us information about the configuration of the valence proton in the ¹⁷Ne. Furthermore, theoretical calculations indicate that the momentum distributions of ¹⁶F c.m are sensitive to the structure of the halo in ¹⁷Ne. Thus the measurement of momentum distributions of ¹⁶F c.m may also give us conclusive information on the structure of ¹⁷Ne. The present experiment has been done at IMP in Lanzhou using the radioactive beam ¹⁷Ne at 30.8 MeV/u on a 43mg/cm^{2 12}C target. The data analysis is under procedure and the primary results are provided.     

Quasi-Elastic Scattering of 16C from 12C at 47.5 MeV/Nucleon

Differential cross sections for the quasi-elastic scattering of^16 C at 47.5 MeV/nucleon from ^12 C target are measured.Coupled-channels calculations are carried out and the optical potential parameters are obtained by fitting the experimental angular distribution.     

通过破裂反应研究轻丰中子核的集团结构

概括介绍了关于轻丰中子同位素链集团结构的理论模型和通过破裂反应研究该结构的实验方法、 实验装置及物理分析。 The theoretical models of the cluster structures of the light neutron rich nuclei as well as the corresponding physical mechanism and experimental approaches by breakup reaction have been introduced, which may serve as references for possible experimental studies of the cluster structure of light neutron rich nuclei. 