Spectroscopy of $^{11}$Be from the $^{10}$Be($d,p$) reaction measured in inverse kinematics by the AT-TPC in SOLARIS

TL;DR

This study investigates the structure of $^{11}$Be using inverse kinematics transfer reactions with the AT-TPC, providing new experimental data and comparing it with advanced theoretical models to understand its low-lying states.

Contribution

First coupling of AT-TPC with SOLARIS for high luminosity transfer reactions, yielding detailed spectroscopic data and validation of ab initio calculations for $^{11}$Be.

Findings

Spectroscopic factors consistent with shell model and NCCI predictions.

Excitation energies agree with literature and ab initio calculations.

Support for positive parity assignment of the 3.40 MeV state.

Abstract

The spectroscopy of $^{11}$Be is explored using the $^{10}$Be$(d,p)$$^{11}$Be transfer reaction performed in inverse kinematics at $9.6\,\MeV/u$ using the Active Target Time Projection Chamber (AT-TPC) inside the SOLARIS solenoid. This experiment is the first attempt at coupling the AT-TPC with SOLARIS to perform a high luminosity transfer reaction measurement without compromising excitation energy and scattering angle resolutions. The angular momentum transfer for states up to $3.40\,\MeV$ are determined from distorted-wave Born approximation analysis of the measured angular distributions, from which the corresponding spectroscopic factors are deduced. These factors are compared with those from various shell model interactions, and those for the $3.40\,\MeV$ state are consistent with a positive parity assignment. Recent \textit{ab initio} no-core configuration interaction (NCCI) calculations with various nucleon-nucleon interactions are presented for the low-lying positive parity states of $^{11}$Be. The excitation energies produced using the Daejeon16 interaction are in good agreement with those found from both this experiment and the literature, thus supporting a positive parity assignment. The $3.40\,\MeV$ state, if assigned a tentative $J^\pi=3/2^+$, would then correspond to the second excited state of the $K^P=1/2^+$ one-neutron halo ground state rotational band also predicted from such NCCI calculations.