The Hoyle state in12C(Ex= 7.654MeV) is characterized by a pronounced 3α cluster configuration. It is involved in the so-called 3α process in stars, that is responsible of12C nucleosynthesis. We studied the decay path of the Hoyle state by using the14N(d, α2)12C(7.654) reaction at 10.5MeV incident energy. We found, with a precision higher of a factor 5 than any other previous experiment, an almost total absence of direct decays by-passing the ground state of8Be. A new upper limit of such a decay width is placed at 0.043% (95% C.L.). Astrophysical 3α process reaction rate calculations have to be consequently revised.
A new high-precision upper limit of direct α-decays from the Hoyle state in 12C
Dell'Aquila, D.;Lombardo, I.;Verde, G.;Acosta, L.;Agodi, C.;Cappuzzello, F.;Carbone, D.;Cavallaro, M.;Cherubini, S.;D'Agata, G.;Francalanza, L.;Guardo, G. L.;Indelicato, I.;La Cognata, M.;Lamia, L.;Pizzone, R. G.;Puglia, S. M. R.;Rapisarda, G. G.;Romano, S.;Santagati, G.;Spartà, R.;Spitaleri, C.;
2017-01-01
Abstract
The Hoyle state in12C(Ex= 7.654MeV) is characterized by a pronounced 3α cluster configuration. It is involved in the so-called 3α process in stars, that is responsible of12C nucleosynthesis. We studied the decay path of the Hoyle state by using the14N(d, α2)12C(7.654) reaction at 10.5MeV incident energy. We found, with a precision higher of a factor 5 than any other previous experiment, an almost total absence of direct decays by-passing the ground state of8Be. A new upper limit of such a decay width is placed at 0.043% (95% C.L.). Astrophysical 3α process reaction rate calculations have to be consequently revised.File in questo prodotto:
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