Isotopic Effects in Prescission Particle Emission

  • Excitation functions of neutron, proton and α-particle emission prior to scission measured in the reactions 28Si+ 164,167,170Er→192,195,198Pb are studied using an extensive fission diffusion model and it is found that the model can well describe the trend of particle multiplicities of Pb isotopes measured experimentally as a function of the bombarding energy,which indicates the existence of isotope effects in prescission particle emission. Moreover, the dependencies of isotope effect on asymmetric fission and fissioning system size are also studied within the framework of a statistical model modified to include the effects of dissipation in fission by systematically investigating prescission particle evaporation of a light In isotope chain and a medium heavy Er isotope chain. Calculations show that in these regions the isotope effect exists,meaning that the isotope effect of prescission particle emission is a general effect. Furthermore this effect appears also in the case of asymmetric fission and it will be enhanced with increasing fission delay time. A new finding is that as the neutron-to-proton ratio of fissioning nuclei increases to a certain extent the prescission proton and α-particle emissions are no longer sensitive to the fission delay time scales. This means that for those neutron-rich fissioning systems proton and α-particle multiplicities will not be good probes for the study of nuclear friction in the fission of hot nuclei.
  • 加载中
  • [1]  Gavron A et al.Phys.Rev.,1987,C35:579—5902 Hinde D J et al.Phys.Rev.1992,C45:1229—12593 Paul P ,Thoennessen M .Annu.Rev.Nucl.Part.Sci.,1994,44:65—1084 Lestone J P .Phys.Rev.Lett.1991,67:1078—10815 Kramers H A .Physica,1940,7:2846 Frobrich P ,GontcharⅡ.Phys.Rep:1998,292:131—2377 Eremin N V .Phys.Lett.,1995,B353:432—4378 Kampen N G .J .Stat.Phys.,1977,17:719 LU Z D et al.Z .Phys.,1986,A323:477—484;Phys.Rev.,1990,C42:707—710 YE W et al.Z .Phys.,1997,A359:385—38910 Delagrange H et al.Z .Phys.,1990,A323:437—449 11 Lestone J P .Nucl.Phys.,1993,A559:277—316 12 Bass R .Nucl.Phys.,1974,A231:45—63 13 Sierk A .Phys.Rev.,1986,C33:2039—2051 14 Myers W D ,Swiatecki W J. Nucl.Phys.,1966,A81:1—23 15 Pomorski K et al.Nucl.Phys.,1996,A605:87—119;Nucl.Phys.,2000,A679:25—53 16 Fiored L et al.Nucl.Phys.,1997,A620:71—80;Nakagawa T et al.,Nucl.Phys.,1995,A583:149—152;Brown C M et al.Phys.Rev.,1999,C60:064612–1–064612–16;Phys.Rev.,2000,C61:054611–1–11;Kaplan M et al.Nucl.Phys.,2001,A686:109—128 17 Charity R J. Nucl.Phys.,1988,A483:371—405 18 Thoennessen M ,Bertsch G F .Phys.Rev.Lett.,1993,71:4303—4306
  • 加载中

Get Citation
YE Wei. Isotopic Effects in Prescission Particle Emission[J]. Chinese Physics C, 2003, 27(3): 233-237.
YE Wei. Isotopic Effects in Prescission Particle Emission[J]. Chinese Physics C, 2003, 27(3): 233-237. shu
Milestone
Received: 2002-03-20
Revised: 1900-01-01
Article Metric

Article Views(3791)
PDF Downloads(651)
Cited by(0)
Policy on re-use
To reuse of subscription content published by CPC, the users need to request permission from CPC, unless the content was published under an Open Access license which automatically permits that type of reuse.
通讯作者: 陈斌, bchen63@163.com
  • 1. 

    沈阳化工大学材料科学与工程学院 沈阳 110142

  1. 本站搜索
  2. 百度学术搜索
  3. 万方数据库搜索
  4. CNKI搜索

Email This Article

Title:
Email:

Isotopic Effects in Prescission Particle Emission

    Corresponding author: YE Wei,
  • Department of Physics, Southeast of University, Nanjing 210096, China

Abstract: Excitation functions of neutron, proton and α-particle emission prior to scission measured in the reactions 28Si+ 164,167,170Er→192,195,198Pb are studied using an extensive fission diffusion model and it is found that the model can well describe the trend of particle multiplicities of Pb isotopes measured experimentally as a function of the bombarding energy,which indicates the existence of isotope effects in prescission particle emission. Moreover, the dependencies of isotope effect on asymmetric fission and fissioning system size are also studied within the framework of a statistical model modified to include the effects of dissipation in fission by systematically investigating prescission particle evaporation of a light In isotope chain and a medium heavy Er isotope chain. Calculations show that in these regions the isotope effect exists,meaning that the isotope effect of prescission particle emission is a general effect. Furthermore this effect appears also in the case of asymmetric fission and it will be enhanced with increasing fission delay time. A new finding is that as the neutron-to-proton ratio of fissioning nuclei increases to a certain extent the prescission proton and α-particle emissions are no longer sensitive to the fission delay time scales. This means that for those neutron-rich fissioning systems proton and α-particle multiplicities will not be good probes for the study of nuclear friction in the fission of hot nuclei.

    HTML

Reference (1)

目录

/

DownLoad:  Full-Size Img  PowerPoint
Return
Return