Constraint on the Ground-state Mass of 21Al and Three-Nucleon Forces

X. Z. Teng; C. E. Teh; J. Lee; X. X. Xu; C. J. Lin; L. J. Sun; J. S. Wang; D. Q. Fang; S. Leblond; Z. H. Li; J. Li; N. R. Ma; J. B. Ma; H. L. Zang; P. Ma; S. L. Jin; M. R. Huang; Z. Bai; J. J. Liu; T. Lokotko; F. Yang; H. M. Jia; D. X. Wang; Y. Y. Yang; Z. G. Hu; M. Wang; H. Q. Zhang

arXiv · 1704.03249

Constraint on the Ground-state Mass of 21Al and Three-Nucleon Forces

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Abstract

Fragmentation cross section of $^{28}$Si + $^{9}$Be reaction at 75.8 MeV/u was analyzed for studying the decay mode of single-proton emission in $^{21}$Al (the proton-rich nucleus with neutron closed-shell of $N = 8$ and $T_z = -5/2$). With the comparison between the measured fragmentation cross section and the theoretical cross section produced by EPAX3.1a for the observed nuclei (i.e. $^{20}$Mg, $^{21}$Al and $^{22}$Si), the expected yield for a particle stable $^{21}$Al was estimated. With the exponential decay law, an upper limit of half-life of $13$ ns was determined. Using the single-proton penetration model, the upper limit of single-proton separation energy of $-105$ keV was deduced. This deduced mass limit agrees with the microscopic calculation based on nucleon-nucleon (NN) + three-nucleon (3N) forces in $sdf_{7/2}p_{3/2}$ valence space, which indicates the importance of 3N forces in $^{21}$Al.

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X. Z. Teng, C. E. Teh, J. Lee, X. X. Xu, C. J. Lin, L. J. Sun, J. S. Wang, D. Q. Fang, S. Leblond, Z. H. Li, J. Li, N. R. Ma, J. B. Ma, H. L. Zang, P. Ma, S. L. Jin, M. R. Huang, Z. Bai, J. J. Liu, T. Lokotko, F. Yang, H. M. Jia, D. X. Wang, Y. Y. Yang, Z. G. Hu, M. Wang, H. Q. Zhang. 2017-04-11. Constraint on the Ground-state Mass of 21Al and Three-Nucleon Forces. https://arxiv.org/abs/1704.03249

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