Pairing energy of fragments produced in intermediate-energy heavy-ion collisions

Chun-Wang Ma (马春旺), Fei Niu (牛菲), Chun-Yuan Qiao (乔春源), Yi-Fei Niu (牛一斐), and Ting-Zhi Yan (颜廷志)
Phys. Rev. C 94, 024615 – Published 22 August 2016

Abstract

The pairing energy (Ep) of fragments, which is assumed to have a finite temperature in heavy-ion collisions, is obtained using an isobaric yield ratio method in the framework of a modified Fisher model. The fragments in the measured and simulated 140A MeV Ca40,48+Be9/Ta181 and Ni58,64+Be9/Ta181 reactions have been adopted to perform the analysis. The results show that the ratio of the pairing-energy coefficient to the temperature (ap/T) is not significantly influenced by the reaction system, but depends on the neutron excess (I=NZ) of the fragment. For most fragments, ap/T falls in the range of 1.0<ap/T<1.0. Assuming T2.0 MeV for the intermediate-mass fragments, ap2.0 MeV is suggested, which is much smaller than the value in the semiclassical mass formula. For a neutron-rich fragment, Ep may disappear. The results are confirmed by the calculated Ep of some A=34 isobars using the self-consistent finite-temperature relativistic Hartree-Bogoliubov model with the effective interaction PC-PK1 and the Gogny-pairing interaction D1S. The calculated Ep depends on T in the form of y=Cexp(aT4) and Ep goes to zero fast with temperatures at around T=0.8 MeV. The results are useful for improving the secondary decay simulation for primary fragments in the heavy-ion collisions.

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  • Received 8 April 2016

DOI:https://doi.org/10.1103/PhysRevC.94.024615

©2016 American Physical Society

Physics Subject Headings (PhySH)

Nuclear Physics

Authors & Affiliations

Chun-Wang Ma (马春旺)1,*, Fei Niu (牛菲)1, Chun-Yuan Qiao (乔春源)1, Yi-Fei Niu (牛一斐)2, and Ting-Zhi Yan (颜廷志)3

  • 1Institute of Particle and Nuclear Physics, Henan Normal University, Xinxiang 453007, China
  • 2INFN, Sezione di Milano, via Celoria 16, I-20133 Milano, Italy
  • 3School of Energy Resources and Power Engineering, Northeast Dianli University, Jilin 132012, China

  • *Corresponding author: machunwang@126.com

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Issue

Vol. 94, Iss. 2 — August 2016

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