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Description
$\beta$-decay can be used as a simple and selective approach to populate certain nuclear excited states and study them. If the imbalance between proton and neutron number is large, levels in the daughter nucleus can be populated above the particle separation energy, leading to single or multi-particle emission. These new decay channels provide an opportunity to study nuclear structure at high excitation energy [1], nuclear astrophysics processes [2] and fundamental symmetries of the weak interaction.
Detecting all the particles emitted after $\beta$-decay with a good efficiency becomes necessary to obtain the full decay path information. It is in this context that the Regina Cube for Multiple Particles (RCMP), ancillary detector for the GRIFFIN HPGe $\gamma$-ray spectrometer at TRIUMF [3] has been developed to explore $\beta$-decay at the proton drip line. RCMP is a set of six double-sided silicon strip detectors (DSSD) arranged in a cubic geometry, allowing to measure the energy of charged particles emitted after $\beta$-decay. Added to GRIFFIN, this state-of-the-art setup is the most effective to date in order to perform this type of study.
This work presents the first results obtained with this experimental setup, where the full $\beta$-delayed spectroscopy of $^{20}$Mg and $^{21}$Mg has been achieved with the highest statistical yield measured to date, providing a significative contribution to the understanding of nuclear structure and astrophysics processes at the proton drip line in the A $\sim$ 20 region.
[1] M. V. Lund et al. “Systematic trends in beta-delayed particle emitting nuclei: The case of βpα emission from $^{21}$Mg”. In: Phys. Lett. B 750 (Nov. 2015)
[2] M. V. Lund et al. “Beta-delayed proton emission from $^{20}$Mg”. In: Eur. Phys. J. A 52.10 (Oct. 2016)
[3] A. B. Garnsworthy et al. “The GRIFFIN facility for Decay-Spectroscopy studies at TRIUMF-ISAC”. In: Nucl. Instrum. Methods Phys. Res., Sect. A 918 (Feb. 2019)