摘要
对 6 0AGeV16O在原子核乳胶中的电磁离解现象首次进行了高统计的研究 ,得到电磁离解截面随束流能量的增加而增加 ,射弹碎片电荷分布和 2 0 0AGeV16O在乳胶中电磁离解的电荷分布一致 ,但电荷为 3≤Z≤ 5的射弹碎片的发射概率低于 2 0 0AGeV能区 ,这些特点和Weiszacker和Williams的经典电磁理论模型计算结果一致 .6 0AGeV16O电磁离解下各反应道出现的概率和 2 0 0AGeV能区结果基本一致 ,但同 14 6AGeV能区的结果不同 ,在6 0AGeV能区16O电磁离解主要是由电偶及电四激发引起的巨偶极和巨四极共振及准氘核效应过程所致 ,这一点可以通过电磁离解下质子的多重数分布得到定性解释 .电磁离解下α射弹碎片的分布同非弹核作用下α碎片的分布规律不同 ,说明α碎片的产生机制不同 .
The electromagnetic dissociations (EDs) of 60 A GeV 16 O in nuclear emulsion is investigated with high statistics for the first time. It is found that the interaction cross section for EDs increases with increasing beam energy, and the charge distribution of projectile fragments is the same as the results at 200 A GeV, but the production probability of projectile fragments with charge 3≤ Z ≤5 is smaller than that of the results at 200 A GeV. These results can be explained by use of the Weizscker Williams method for calculating the EDs contributions. The percentage abundances of various decay modes for EDs at 60 A GeV is the same as the results at 200 A GeV,but different from the results at 14.6 A GeV. The EDs of 60 A GeV 16 O is mainly caused by the giant dipole and quadrupole resonance of E1 and E2 and by the quasi deuteron effect, which can be qualitatively explained by the multiplicity distribution of projectile fragmentation proton in EDs. The multiplicity distribution of α fragments in EDs and nuclear events have different functional forms. This difference may be a consequence of the different reaction mechanisms involved in EDs and nuclear events.
出处
《物理学报》
SCIE
EI
CAS
CSCD
北大核心
2000年第10期1938-1946,共9页
Acta Physica Sinica
基金
山西省青年科学基金!(批准号 :9910 0 4)
山西省归国人员基金资助的课题&&
