Isochronous mass measurements of neutron-deficient nuclei from Sn112 projectile fragmentation

Abstract

Masses of Sn112 projectile fragments were measured employing isochronous mass spectrometry at the Cooler Storage Ring in Lanzhou. Different from the previous data analysis method, relying on the arithmetic mean revolution times of the stored fragments, we introduce an exponentially modified Gaussian function to describe the asymmetric peak shapes. This new approach enables us to properly deconvolute the overlapping peaks of stored ions and to accurately determine their masses. The mass excesses of Sn103 and the low-lying 1/2− isomers in Mo87, Ru91, and Pd95 were directly measured for the first time, and the masses of As69, Br73, Kr75, Sr79, and Y81 were redetermined with higher precision comparable to that of Penning-trap mass spectrometry. Based on the new mass value of Sn103, the previously unknown masses of Sb104, Te107, I108, Xe111, and Cs112 were obtained indirectly by using the literature proton and/or α decay energies. Systematic trends of the excitation energies of the Jπ=1/2− isomers in the N=47,49 isotones are well reproduced by the state-of-the-art shell model calculations with the tensor forces included.7 MoreReceived 30 March 2022Accepted 9 December 2022DOI:https://doi.org/10.1103/PhysRevC.107.014304©2023 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasBinding energy & massesNuclear forcesNuclear fragmentationNuclear structure & decaysShell modelProperties59 ≤ A ≤ 8990 ≤ A ≤ 149TechniquesNuclear data analysis & compilationSpectrometers & spectroscopic techniquesNuclear Physics