Study of 12Be structure in multi-threshold vicinity with ACTAR TPC

by Laurie Dienis (2nd year PhD student)

This ACTAR TPC experiment, conducted in March 2024 at GANIL, investigated clustering phenomena in 12Be
via the 4He(8He, 8He)4He resonant elastic scattering reaction. Previous studies, notably by Yang et al. (2014),
confirmed the presence of a resonance at 12.1 MeV, located near several particle-emission thresholds. This state,
identified as a narrow resonance (width < 0.8 MeV), is particularly interesting in the context of the role of multi-
threshold proximity in light nuclear clustering.

In this experiment, the ACTAR TPC, filled with helium gas and isobutane, allowed for the measurement of
excitation energies between 11.5 and 13 MeV with an energy resolution of 200 keV FWHM, significantly improving
upon the 800 keV resolution reported in previous studies. The ability to scan different energy intervals, depending
on beam energy and gas pressure, provided a comprehensive exploration of this region. Additionally, this setup
enabled precise measurements of angular distributions and facilitated the determination of spin-parity assignments
for observed resonances. These results might offer new insights into the clustering dynamics of light nuclei near
multi-particle emission thresholds. This talk will present the latest results from the ongoing data analysis.