Abstract
By using isochronous mass spectrometry at the experimental cooler storage ring in Lanzhou, China, masses of short-lived , , , , and were measured for the first time and the precision of the mass of was improved by a factor of about 2. Relative precisions of have been achieved. Details of the measurements and data analysis are given. The obtained masses are compared with the Atomic-Mass Evaluation 2016 and with theoretical model predictions. The new mass data enable us to extract the higher-order coefficients, and , of the quartic form of the isobaric multiplet mass equation for the -shell isospin quintets. Unexpectedly large and values for the quintet are found. By revisiting the previous experimental data on -delayed protons from decay, it is suggested that the observed anomaly could be due to the misidentification of the , isobaric analog state in .
3 More- Received 10 September 2020
- Accepted 22 October 2020
DOI:https://doi.org/10.1103/PhysRevC.102.054311
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