The rare double gamma decay of the first excited 0+ state in Ca40 and Zr90 has been measured with a segmented 4π NaI detector system, which allows suppression of the perturbing background due to positron annihilation in flight. In both cases the directional correlation of the two photons is found to be asymmetric around 90°, which is explained by an interference of 2E1 and 2M1 transitions. The deduced M1 quenching factors agree with those from (e,e′) and (p,p′) measurements.
ASJC Scopus subject areas
- Physics and Astronomy(all)