Speaker
Description
The region of the nuclear chart near the doubly-magic $^{100}$Sn is of crucial importance for understanding the atomic nucleus and an excellent testing ground for state-of-the-art nuclear models. $^{100}$Sn is the heaviest doubly-magic $N = Z$ nucleus, and additionally represents the end of the astrophysical rp-process. Experimental constraints of the single-particle orbits outside $^{100}$Sn are crucial to understand the region. In recent years there has been much discussion regarding the lowest-lying excited state of Sn, which lies at 172 keV. The spin and parity ordering of the two lowest-lying states $(J^{\pi} = 5/2^{+}, 7/2^+)$ is still unknown, and this ordering directly relates to the $\nu d_{5/2}, g_{7/2}$ single particle orbitals which inform the structure of the whole region [1, 2].
Thus, an experimental determination of the spin and parity of these low-lying states is imperative. The lightest Sn isotope for which the ordering has been experimentally measured is $^{107}$Sn [3]. Results from single neutron knockout reactions on beams of $^{104,102}$Cd and $^{104}$Sn will be presented. Neutron knockout is an excellent probe of single-particle structure, effectively utilizing weak beams, and providing a measure of the angular momentum transfer and wavefunction purity. The experiment was conducted at the Facility for Rare Isotope Beams, using the GRETINA array and the S800 spectrograph. The high-statistics $^{104,102}$Cd data provides insight into the neutron knockout reaction mechanism, with direct population of high-spin states showing down-shifted momentum distributions.
[1] D. Seweryniak et al., Phys. Rev. Lett. 99, 022504 (2007)
[2] I. Darby et al., Phys. Rev. Lett. 105 162502 (2010)
[3] G. Cerizza et al. Phys. Rev. C 93, 0221601 (R) (2016)
| Contribution category | Experiment |
|---|---|
| Presenter status | Faculty/Staff |