Speaker
Description
Looking from the last stable isotope at $^{48}$Ca towards the neutron-rich exotic Ca isotopes, recent mass measurements and high $2^+_1$ energies predict closures of the N = 32 and N = 34 neutron sub-shells, while a monotonic increase in the nuclear radii from $^{48}$Ca to $^{52}$Ca suggests otherwise. Lifetime measurements of low-lying states in the yrast bands of $^{50,51,52}$Ca provide a mechanism of probing the largely unconstrained $B(E2)$ values for these states, providing a stringent test for the shell-model interactions in this region.
In 2024 at INFN LNL, a 305 MeV beam of $^{48}$Ca beam was delivered to a $^{238}$U target at the combined AGATA/PRISMA experimental station, populating $^{48-52}$Ca, among other nearby isotopes, in a multi-nucleon transfer reaction. Surrounding the $^{238}$U target, the high-purity germanium Advanced GAmma Tracking Array (AGATA) was used to measure high-resolution $\gamma$-ray lineshapes from the states in the excited isotopes. These emitted recoil isotopes were then collected in the PRISMA large acceptance magnetic spectrometer, providing event-by-event resolution of the mass and atomic number. Two target configurations were used to study two distinct lifetime ranges using the Doppler-shift attenuation method (DSAM) and recoil distance Doppler-shift (RDDS) technique. In this contribution, we will discuss the preliminary analysis of states in the Ca isotopes beyond N = 28.