PHYSICAL REVIEW C VOLUME 3-8, NUMBER 4 Isovector and isotensor Coulomb energies for 61 ( A (209 OCTOBER 1988 A. Pape and M. S. Antony Centre de Recherches Nucleaires and Universite Louis Pasteur, 67037 Strasbourg Cedex, France A. Georgiadis Research Center of Crete, Heraklio, Crete, Greece (Received 30 November 1987; revised manuscript received 17 June 1988) Isovector Ec" and isotensor Ec ' parts of the nuclear Coulomb energy for 61 & A & 209 have been extracted from energies of corresponding states using the isobaric mass equation. These Ec" and Ec ' continue to show the same overall variation, linear in A and approximately A ', respec- tively, as do the values for A & 60. In earlier work' the b and c coefficients for A (60 of the isobaric multiplet mass equation (IMME) M=a+bT, +CT, , where T, = (N — Z)/2 have been obtained by fitting com- plete isobaric multiplets. In this mass region where the IMME is known to hold, and particularly for A &45, values of b and c have been established. Above A =60, no complete multiplets have been measured and little in- formation on the coefficients exists. It is nevertheless E~"— — h„H — b, E, "'=c Z3 . (2) possible using experimentally determined excitation ener- gies of analog states to calculate values of b and c up to A =209, and to give the more fundamental quantities, the isovector E&" and isotensor Ez ' terms of the nuclear Coulomb energy. They are related to b and c by the fol- lowing equations: 30 20 I 40 I 60 80 t 1 A 100 I 125 t 150 175 200 I 1 1 ) CJ X: LJ LaJ 25— 20— 15— t / xgg . -I X 10— ~ with error ~ no error 0 0 I I I I I I I I I I I I I I I I I I I I I I I I I I I I I 10 15 20 25 30 35 A 2/3 FIG. 1. E&" as a function of A, where the line is the equation Ec" —— 0. 7053 A — 0. 8299 MeV. The five larger points represent two near-lying values. Uncertainties &100 keV are not shown. For A &60, all errors are within the size of the smaller dots ( 50 keV) except for one point at A = 5, 39, 43, 47, 49, 51, and 56 which have errors of 53 — 100 keV. 38 1952 1988 The American Physical Society