Direct reaction measurements with a 132Sn radioactive ion beam

TL;DR

This study performed direct reaction measurements using a radioactive 132Sn beam to explore neutron transfer and elastic scattering, revealing new nuclear states and validating reaction models with implications for nuclear structure near shell closures.

Contribution

It provides the first measurement of a specific neutron state in 132Sn using inverse kinematics, and compares reaction analysis methods to improve nuclear structure understanding.

Findings

Identified a new state at 1363 keV in 132Sn.

Confirmed the consistency of angular distributions with previous spin assignments.

Spectroscopic factors are similar to those in 208Pb.

Abstract

The (d,p) neutron transfer and (d,d) elastic scattering reactions were measured in inverse kinematics using a radioactive ion beam of 132Sn at 630 MeV. The elastic scattering data were taken in a region where Rutherford scattering dominated the reaction, and nuclear effects account for less than 8% of the cross section. The magnitude of the nuclear effects was found to be independent of the optical potential used, allowing the transfer data to be normalized in a reliable manner. The neutron-transfer reaction populated a previously unmeasured state at 1363 keV, which is most likely the single-particle 3p1/2 state expected above the N=82 shell closure. The data were analyzed using finite range adiabatic wave calculations and the results compared with the previous analysis using the distorted wave Born approximation. Angular distributions for the ground and first excited states are consistent with the previous tentative spin and parity assignments. Spectroscopic factors extracted from the differential cross sections are similar to those found for the one neutron states beyond the benchmark doubly-magic nucleus 208Pb.