Structure Studies of $^{13}\text{Be}$ from the $^{12}$Be(d,p) reaction in inverse kinematics on a solid deuteron target

TL;DR

This study investigates the structure of the unbound nucleus $^{13}$Be using the $^{12}$Be(d,p) reaction in inverse kinematics, employing a solid deuteron target and Bayesian analysis to clarify its resonance properties.

Contribution

It provides new experimental data on $^{13}$Be's low-lying states using a thick solid deuteron target and Bayesian analysis, resolving inconsistencies from previous studies.

Findings

Results favor a narrow width for the $^{13}$Be resonance.

Data are incompatible with wide $5/2^+$ resonance reports.

Better agreement with studies reporting narrower resonances.

Abstract

The low-lying structure of $^{13}$Be has remained an enigma for decades. Despite numerous experimental and theoretical studies, large inconsistencies remain. Being both unbound, and one neutron away from $^{14}$Be, the heaviest bound beryllium nucleus, $^{13}$Be is difficult to study through simple reactions with weak radioactive ion beams or more complex reactions with stable-ion beams. Here, we present the results of a study using the $^{12}$Be(d,p)$^{13}$Be reaction in inverse kinematics using a 9.5~MeV per nucleon $^{12}$Be beam from the ISAC-II facility. The solid deuteron target of IRIS was used to achieve an increased areal thickness compared to conventional deuterated polyethylene targets. The Q-value spectrum below -4.4~MeV was analyzed using a Bayesian method with GEANT4 simulations. A three-point angular distribution with the same Q-value gate was fit with a mixture of $s$- and $p$-wave, $s$- and $d$-wave, or pure $p$-wave transfer. The Q-value spectrum was also compared with GEANT simulations obtained using the energies and widths of states reported in four previous works. It was found that our results are incompatible with works that revealed a wide $5/2^+$ resonance but shows better agreement with ones that reported a narrower width.