Abstract
Isochronous mass spectrometry has been applied in the storage ring CSRe to measure the masses of the nuclei and . The new mass excess value is 66(52) keV larger than the result of the previous reaction measurement in 1973 and a factor of 3.8 more precise. The new result for together with those of the isobaric analog states in , and fit well into the quadratic form of the isobaric multiplet mass equation (IMME). The mass excess of has been remeasured to be . By analyzing the linear and quadratic coefficients of the IMME in the -shell nuclei, it was found that the ratio of the Coulomb radius parameters is and is nearly the same for all isospin multiplets. Such a nearly constant value, apparently valid for the entire light mass region with , can be used to set stringent constraints on the isovector and isotensor components of the isospin nonconserving forces in theoretical calculations.
- Received 26 September 2017
- Revised 7 May 2018
DOI:https://doi.org/10.1103/PhysRevC.98.014315
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