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تسجيل مستخدم جديدIndependent measurement of the Hoyle state $beta$ feeding from 12B using Gammasphere
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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.
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The cascading 3.21 MeV and 4.44 MeV electric quadrupole transitions have been observed from the Hoyle state at 7.65 MeV excitation energy in $^{12}$C, excited by the $^{12}$C(p,p$^{prime}$) reaction at 10.7 MeV proton energy. From the proton-$gamma$-
$gamma$ triple coincidence data, a value of ${Gamma_{rm rad}}/{Gamma}=6.2(6) times 10^{-4}$ was obtained for the radiative branching ratio. Using our results, together with ${Gamma_{pi}^{E0}}/{Gamma}$ from Eriksen et al., Phys. Rev. C 102, 024320 and the currently adopted $Gamma_{pi}(E0)$ values, the radiative width of the Hoyle state is determined as $Gamma_{rm rad}=5.1(6) times 10^{-3}$ eV. This value is about 34% higher than the currently adopted value and will impact on models of stellar evolution and nucleosynthesis.
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