Isotopic Effects in Prescission Particle Emission

YE Wei

Chinese Physics C> 2003, Vol. 27> Issue(3) : 233-237

Isotopic Effects in Prescission Particle Emission

YE Wei ^,

Department of Physics, Southeast of University, Nanjing 210096, China

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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.

References

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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

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Received: 2002-03-20
Revised: 1900-01-01

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通讯作者: 陈斌, bchen63@163.com

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沈阳化工大学材料科学与工程学院沈阳 110142

Isotopic Effects in Prescission Particle Emission

Corresponding author: YE Wei,

Department of Physics, Southeast of University, Nanjing 210096, China

Received Date: 2002-03-20

Accepted Date: 1900-01-01

Available Online: 2003-03-05

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.

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