Speaker
Description
Nuclear spin orientation provides access to an additional observable in beta-decay experiments – the anisotropy of radiation emission, which reflects the parity-nonconserving nature of the weak interaction [1]. The resulting directional distribution of the radiation depends on the asymmetry parameter, which is sensitive to the angular momentum change, as well as on the polarization of the parent nuclei. Higher beam polarization leads to more pronounced anisotropy, which can be used to determine the asymmetry parameter and thereby assign the spins and parities of excited states. Such assignments are particularly straightforward for states involved in allowed Gamow–Teller transitions, as demonstrated in experiments at RIKEN [2, 3] and TRIUMF [4, 5], where beta-decay spectroscopy with polarized nuclei was pioneered.
In this contribution, the CERN ISOLDE’s first beta-decay spectroscopy experiment with laser-polarized beams is presented. A dedicated station has been designed and integrated into the VITO beamline [6]. Full compatibility of the new setup was demonstrated in commissioning campaigns with polarized atoms of 47,49,51K. The new station at VITO opens opportunities to advance beta-decay studies at ISOLDE and to provide new insights into the decay mechanisms of strong beta-delayed neutron emitters [7, 8].
[1] K. S. Krane, In: H. Postma, N. J. Stone, Low Temp. Nucl. Orient., North Holland, 1986.
[2] H. Miyatake et al., Phys. Rev. C 67, 014306 (2003).
[3] H. Ueno et al., Phys. Rev. C 87, 034316 (2013).
[4] Y. Hirayama et al., Physics Letters B 611, 239 (2005).
[5] H. Nishibata et al., Phys. Rev. C 111, 064317 (2025).
[6] M. Kowalska et al., Phys. G: Nucl. Part. Phys. 44, 084005 (2017).
[7] Z. Y. Xu, R. Grzywacz et al., Phys. Rev. Lett. 133, 042501 (2024).
[8] P. Dyszel, R. Grzywacz et al., Phys. Rev. Lett. 135, 152501 (2025).
Funded by the European Union's HORIZON Programme under the Grant Agreement No. 101212216 (RADESO).