基于HIRFL-RIBLL1装置的放射性核弹性散射和破裂反应研究进展  

Progress on elastic scattering and breakup of radioactive nuclei based on the HIRFL-RIBLL1

作　　者：杨彦云[1,2] 杨过 王康 段芳芳 Yanyun Yang;Guo Yang;Kang Wang;Fangfang Duan(Institute of Modern Physics,Chinese Academy of Sciences,Lanzhou 730000,China;School of Nuclear Science and Technology,University of Chinese Academy of Sciences,Beijing 100080,China)

机构地区：[1]中国科学院近代物理研究所,兰州730000 [2]中国科学院大学核科学与技术学院,北京100080

出　　处：《科学通报》2022年第23期2727-2735,共9页Chinese Science Bulletin

基　　金：国家自然科学基金(12122511,U1632138,11575256,11005127,12105330)资助。

摘　　要：放射性核束物理是当前核物理研究的重点领域之一,直接核反应是研究放射性核的反应机制和奇特结构的重要方法.本文回顾了近年来在HIRFL-RIBLL1上开展的放射性核的弹性散射和破裂反应研究,并介绍了国际上的研究现状.通过对典型中子晕核^(11)Be和质子滴线核^(8)B在高于库仑势垒能区弹性散射的系统性比较研究,明确了即使在3倍库仑势垒附近的能区,破裂反应道仍然会对丰中子核的弹性散射道有强烈的耦合效应.研究表明,与入射能量相比,破裂反应对其他反应道耦合效应的强弱对奇特核的核结构更加敏感.此项研究加深了学界对放射性核反应动力学的认识.无论是丰中子核还是丰质子核,去弹破裂都在破裂反应中起到重要的作用,尤其在大角度范围内.总体而言,丰质子核的破裂截面明显小于丰中子核.同时理论研究表明,紧密束缚核的破裂反应主要来自去弹破裂的贡献,对破裂反应机制的理解还需要开展进一步的实验研究.Studying reaction mechanisms and structures of radioactive nuclei is an important frontier of current nuclear physics studies.Research progress on elastic scattering and breakup reactions induced by neutron-rich nucleus ^(11)Be and proton-rich nucleus ^(8)B is reviewed in this paper.A novel method is presented for the measurement of elastic scattering and breakup reactions angular distributions induced by radioactive ion beams(RIBs)at HIRFL-RIBLL1(Radioactive Ion Beam Line in Lanzhou,Heavy-Ion Research Facility in Lanzhou).RIBLL1 is a typical projectile fragmentation(PF)type facility,which has the advantage of providing the short lifetime RIBs and the disadvantage of a broad beam profile.The disadvantage of this production mechanism was overcome through the proposal of a new experimental method.The radioactive beams were identified by applying a time-of-flight and energy loss(TOF-ΔE)technique with a certain magnetic rigidity Bρvalue in which the TOF was measured using two plastic scintillation detectors.Two position detectors,named PPAC(parallel-plate avalanche counter)or thin DSSD(double-sided silicon strip detector),were used to measure the position and the direction of the incoming beam.A telescope array consisting of DSSDs and SSDs(single silicon detectors)was used to identify the reaction events and measure the scattered angle.The data normalization and small corrections for the misalignment of detectors were performed by assuming the ratio of the elastic cross section to the Rutherford cross section is approximately equal to 1 at small angles.A set of experimental studies of elastic scattering and breakup reactions induced by both of neutron-rich and proton-rich radioactive nuclei at the energies above the Coulomb barriers were performed at HIRFLRIBLL1.The ^(11)Be elastic scattering angular distribution shows a strong breakup coupling effect at a relatively high incident energy for the first time,in contrast to what was observed for proton-rich nuclei at similar energies.The results for proton-rich nuclei

关 键 词：HIRFL-RIBLL1 放射性核 弹性散射 破裂反应 耦合道效应 

分 类 号：O571[理学—粒子物理与原子核物理]