Independent measurement of the Hoyle state $\beta$ feeding from 12B using Gammasphere

TL;DR

This study independently measured the beta decay branching ratio from 12B to the Hoyle state in 12C, finding a smaller value than previous reports and providing new insights into the state's clustering nature.

Contribution

It presents the first measurement of the Hoyle state's gamma cascade angular correlation and a revised beta decay branching ratio, challenging prior assumptions.

Findings

Beta decay branching ratio to Hoyle state is 0.64(11)%

Angular correlation matches theoretical predictions

Suggests the Hoyle state is more clustered than previously thought

Abstract

Using an array of high-purity Compton-suppressed germanium detectors, we performed an independent measurement of the $\beta$-decay branching ratio from $^{12}\mathrm{B}$ to the second-excited (Hoyle) state in $^{12}\mathrm{C}$. Our result is $0.64(11)\%$, which is a factor $\sim 2$ smaller than the previously established literature value, but is in agreement with another recent measurement. This could indicate that the Hoyle state is more clustered than previously believed. The angular correlation of the Hoyle state $\gamma$ cascade has also been measured for the first time. It is consistent with theoretical predictions.