30MeV/u40_Ar+nat_Ag反应中中等质量碎片的发射时标

Time Scsle for Emission of Intermediate Mass Fragments in E/A= 30MeV 40Ar+natAg Beaction*

采用强度干涉技术，研究了３０ＭｅＶ／ｕ４０Ａｒ＋ａｎｇＡｇ反应中ＩＭＦ－ＩＭＦ关联的实验结果。利用三体弹道模型从约化速度关联函数提取了中等质量碎片的发射时间。中等质量碎片的平均发射时间随其能量而变化，从低能时的约３００ｆｍ／ｃ下降到高能时的约１００ｆｍ／ｃ。扣除类弹碎片的贡献后，得到此反应发射中途中等质量碎片的平均发射时间约为２５０ｆｍ／ｃ，表明此反应发射的中等质皇碎片主要来自于相继两体衰变。

Fragment-fragment conelation functions have been measured in E/A= 30 MeV 40Ar+natAg reaction via the technique of intensity interferometry. Emission times of intermediate mass fragments have been extracted from reduced velocity correlation functions by using the threebody trajectory model. The average emission time of intermediate mass fragments varies with the energy of fragments. It decreases from about 300fm/c for low energy fragments to about 80 fm/c for energetic fragments. After subtmcting the contribution of projectile-like fragments, average emission times of mid-rapidity fragments are of the order of 250 fm/c for this reaction.It indicates that intermediate mass fragments emitted in this reaction mainly come from sequential binary decays.