Highly Proton-Rich <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>T</mi></mrow><mrow><mi>z</mi></mrow></msub></mrow><mo>=</mo><mo>−</mo><mn>2</mn><mn></mn></math> Nuclides: <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mmultiscripts><mrow><mi mathvariant="normal">C</mi></mrow><mprescripts></mprescripts><mrow></mrow><mrow><mn>8</mn></mrow><mrow></mrow><mrow></mrow></mmultiscripts></mrow></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mmultiscripts><mrow><mi mathvariant="normal">Mg</mi></mrow><mprescripts></mprescripts><mrow></mrow><mrow><mn>20</mn></mrow><mrow></mrow><mrow></mrow></mmultiscripts></mrow></math>

R. G. H. Robertson; S. Martin; W. R. Falk; D. Ingham; A. Djaloeis

doi:10.1103/PhysRevLett.32.1207

Highly Proton-Rich $T_{z} = - 2$ Nuclides: ${}^{8}C$ and ${}^{20}{Mg}$

R. G. H. Robertson, S. Martin, W. R. Falk, D. Ingham, and A. Djaloeis

Phys. Rev. Lett. 32, 1207 – Published 27 May 1974

Abstract

Two nuclides with a proton excess of 4 have been produced via the ( $α, {}^{8}{He}$ ) reaction, and their masses measured. The mass excess of ${}_{6}^{8}C$ is 35.30 ± 0.20 MeV, and ${}^{8}C$ is therefore unbound with a measured width of $220_{- 140}^{+ 80}$ keV. The ${}^{8}C$ mass excess is 0.57 MeV less than the Kelson-Garvey prediction. For ${}_{12}^{20}{Mg}$ , a mass excess of 17.74 ± 0.21 MeV is found, indicating that ${}^{20}{Mg}$ is nucleon stable. Knowledge of the ${}^{20}{Mg}$ mass permits for the first time a test of the isobaric multiplet mass equation in an isobaric quintet, and good agreement is found.