Mass measurements for $T_z=-2$ $fp$-shell nuclei ${}^{40}$Ti, ${}^{44}$Cr, ${}^{46}$Mn, ${}^{48}$Fe, ${}^{50}$Co and ${}^{52}$Ni

Abstract

By using isochronous mass spectrometry (IMS) at the experimental cooler storage ring CSRe, masses of short-lived ${}^{44}$Cr, ${}^{46}$Mn, ${}^{48}$Fe, ${}^{50}$Co and ${}^{52}$Ni were measured for the first time and the precision of the mass of ${}^{40}$Ti was improved by a factor of about 2. Relative precisions of $\delta m/m=(1-2)\times$10${}^{-6}$ have been achieved. Details of the measurements and data analysis are described. The obtained masses are compared with the Atomic-Mass Evaluation 2016 (AME${}^{\prime }$16) and with theoretical model predictions. The new mass data enable us to extract the higher order coefficients, $d$ and $e$, of the quartic form of the isobaric multiplet mass equation (IMME) for the $fp$-shell isospin quintets. Unexpectedly large $d$- and $e$-values for $A=44$ quintet are found. By re-visiting the previous experimental data on $\beta$-delayed protons from ${}^{44}$Cr decay, it is suggested that the observed anomaly could be due to the misidentification of the $T=2$, $J^{\pi }=0^{+}$ isobaric analog state (IAS) in ${}^{44}$V.

References in corpus (9)

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