# Nuclear Physics Seminar: Samuel Henderson, University of Notre Dame

**Measuring B(E2) values in light radioactive nuclei to guide ab initio calculations**

Samuel Henderson

Graduate Student

University of Notre Dame

Measuring electromagnetic transition strengths can provide stringent tests of nuclear *ab initio* calculations in low mass nuclei (A<20). In this mass region, there are a limited number of electromagnetic transition strength measurements available, especially for unstable nuclei. An experiment was performed with a ^{7}Be beam at the University of Notre Dame Nuclear Science Laboratory to measure the E2 transition strength of the first excited state of 7Be. The 7Be was produced and separated with TwinSol and the γ-ray yields were measured in coincidence with scattered ^{7}Be. This measurement of the ^{7}Be B(E2; 3/2 -→1/2 - ), along with a previous measurement of the ^{7}Li B(E2; 3/2 -→1/2 - ), has been used to benchmark a variety of *ab initio* calculations. These tests were continued by extending into the A=8 region and a similar Coulomb excitation experiment was performed to measure the B(E2; 2 +→1 + ) of the first excited state of 8Li. These two experiments, as well as the comparison of their results to *ab initio* calculations, will be presented. For the A=7 isobars, *ab initio* calculations with a variety of nuclear interactions used were all seen to agree with the experiment result, bolstering confidence in the reliability of these calculations. However, the *ab initio* calculations largely do not agree with the experimental measurement of ^{8}Li and much greater variation between the calculated values is seen. While the reason for this discrepancy in these comparisons can tentatively be explained within the *ab initio* framework, this ^{8}Li transition strength still presents a new challenge for these *ab initio* calculations to meet.

*Hosted by Prof. Wiescher*

*All interested persons are invited to attend remotely—email physics@nd.edu for information.*