Application of isochronous mass spectrometry for the study of angular momentum population in projectile fragmentation reactions

Abstract

Isochronous mass spectrometry was applied to measure isomeric yield ratios of fragmentation reaction products. This approach is complementary to conventional γ-ray spectroscopy in particular for measuring yield ratios for long-lived isomeric states. Isomeric yield ratios for the high-spin I = 19/2h states in the mirror nuclei 53 Fe and 53 Co are measured to study angular momentum population following the projectile fragmentation of 78 Kr at energies of ∼ 480 A MeV on a beryllium target. The 19/2 state isomeric ratios of 53 Fe produced from different projectiles in literature have also been extracted as a function of mass number difference between projectile and fragment (mass loss). The results are compared to ABRABLA07 model calculations. The isomeric ratios of 53 Fe produced using different projectiles suggest that the theory underestimates not only the previously reported dependence on the spin but also the dependence on the mass loss.

Improving the resolving power of Isochronous Mass Spectrometry by employing an in-ring mechanical slit

“…A possible explanation for this dependence is that the momentum distribution for each nuclide is different, as discussed in Ref. [41,42]. Without the slit, nuclei within the entire acceptance of CSRe can be stored in the ring.…”

Heavy-ion storage rings and their use in precision experiments with highly charged ions

“…The small injection acceptance of the ring allows for probing the momentum distribution of the fragment beam in front of the ring. For instance, by comparing the isomeric ratios of 53 Co and 53 Fe in the ESR and CSRe produced in fragmentation reactions of different projectiles conclusions could be drawn on the angular momentum population [166] as well as on the constancy of the isomeric ratio for different longitudinal momenta [167]. The measured odd-even staggering of fragment yields allowed for The ESR was tuned into isochronous mode for primary 238 U 91+ ions which have M/Q = 2.615.…”