Coefficients of the Isobaric Mass Equation and Their Correlations With Various Nuclear Parameters

Elucidation of the AnomalousA=9Isospin Quartet Behavior

“…For instance, it is used to obtain masses of nuclei along the rapid proton capture path, where most of the masses are not well known [5] or to provide detailed mass values, which are experimentally inaccessible due to half-life and productions constraints [6]. Recently, the precise mass measurement of 12 Be [7] using the TITAN (TRIUMF Ion Traps for Atomic and Nuclear science) Penning trap mass spectrometer [8,9] has been used as a solid anchor point together with the IMME to address the ambiguous spin assignment of T = 2 states in 12 C and 12 Be.Several tests of the IMME were performed and for most cases, it has followed the original quadratic behaviour [10]. However, in some cases, large deviations were discovered and the incorporation of cubic d(A, T )T [17,18] quintets.…”

“…Several tests of the IMME were performed and for most cases, it has followed the original quadratic behaviour [10]. However, in some cases, large deviations were discovered and the incorporation of cubic d(A, T )T [17,18] quintets.…”

“…The A = 9 isobars are of particular interest because it is the first and lightest chain presenting two different IMME quartets [21,26]. The ground state quartet [21] strongly departs from quadrature with a quadratic fit χ 2 of 10.2 and a cubic coefficient d = 5.5(18) keV [10]. Several mechanisms to explain this departure have been proposed including the Coulombdependent Thomas-Ehrman shift [27] arising from the small binding energy of the last proton in 9 C and nonCoulomb charge-dependant forces [12].…”

Isobaric multiplet mass equation in theA=31,T=3/2quartets

“…As discussed in Refs. [6] and [7], in situations where the fit of the quadratic form is very poor, a cubic or quartic form with extra terms dT 3 z or eT 4 z may be required. Typically, these terms have been determined empirically to be either very small, 1 keV, or consistent with zero.…”

“…A 1977 experimental measurement of the 36 Ar( 3 He, 8 Li) 31 Cl Q-value resulted in a mass excess value of ∆ = −7070 ± 50 keV [20]. Subsequent evalutions of the IMME [6][7][8]21] 31 Si [27][28][29]), the 50-keV uncertainty in the 31 Cl mass excess has hindered attempts to test the IMME stringently in the lowest quartet. A recent Penning trap mass measurement of 31 Cl finally obtained a value for the ground state mass excess 15 times more precise than previous estimates [30], leading to an IMME breakdown in the lowest quartet; the IMME fit required an unusually large cubic term, with d = −3.5(11) keV.…”