Precise Lifetime Measurements in Light Nuclei for Benchmarking Modern Ab-initio Nuclear Structure Models

Abstract

A new generation of ab-initio calculations, based on realistic two-and three-body forces, is having a profound impact on our view of how nuclei work. To improve the numerical methods, and the parameterization of 3-body forces, new precise data are needed. Electromagnetic transitions are very sensitive to the dynamics which drive mixing between configurations. We have made a series of precise (<3%) measurements of electromagnetic transitions in the A=10 nuclei 10 C and 10 Be by using the Doppler Shift Attenuation method carefully. Many interesting features can be reproduced including the strong α clustering. New measurements on 8 Be and 12 Be highlight the interplay between the alpha clusters and their valence neutrons.

First measurement of the B(E2;3/2−→1/2− ) transition strength in Henderson1, Ahn2, Caprio3 et al. 2019Phys. Rev. C

“…By impinging the beam onto a 2 H gas cell at 800 Torr, we produced 7 Be through the 6 Li( 2 H, n) 7 Be reaction. The secondary 7 Be beam had an energy of 31.3 (10) MeV and was collected and separated from competing reaction products using the two superconducting solenoid magnets of TwinSol [45]. A diagram of the TwinSol beamline is shown in Fig.…”

“…In addition, electromagnetic observables can provide a stringent test of ab initio nuclear theory. For instance, several electromagnetic transition strengths have been determined to high precision in A = 10 nuclei using lifetime and branching ratio measurements and then compared to ab initio quantum Monte Carlo calculations [8][9][10][11]. It was found that the calculated E2 transition strengths were sensitive to the threebody interaction used.…”