EPJ Web of Conferences (Jan 2018)

The α-decay of the Hoyle state in 12C: a new high-precision investigation

  • Dell‘Aquila D.,
  • Lombardo I.,
  • Verde G.,
  • Vigilante M.,
  • Acosta L.,
  • Agodi C.,
  • Cappuzzello F.,
  • Carbone D.,
  • Cavallaro M.,
  • Cherubini S.,
  • Cvetinovic A.,
  • D‘Agata G.,
  • Francalanza L.,
  • Guardo G.L.,
  • Gulino M.,
  • Indelicato I.,
  • La Cognata M.,
  • Lamia L.,
  • Ordine A.,
  • Pizzone R.G.,
  • Puglia S.M.R.,
  • Rapisarda G.G.,
  • Romano S.,
  • Santagati G.,
  • Spartà R.,
  • Spadaccini G.,
  • Spitaleri C.,
  • Tumino A.

DOI
https://doi.org/10.1051/epjconf/201818401005
Journal volume & issue
Vol. 184
p. 01005

Abstract

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The αdecay path of the Hoyle state in 12C (Ex = 7:654MeV) represents one ofthe most challenging questions of modern nuclear physics. Its knowledge can help in theunderstanding of cluster configurations in light nuclei and the possible existence of Bose-Einstein condensates in nuclei. In stars, it is involved in the so-called 3αprocess, wherethe 12C nucleosynthesis occurs. We studied the 14N(d; α2)12C(7:654) reaction at 10:5MeVincident energy to probe its direct decay component. We found, with a precision higherof a factor 5 than any other previous experiment, an almost total absence of direct decaysby-passing the ground state of 8Be. From our analysis, a new upper limit of such decayis found at 0:043% (95% C.L.). Astrophysical 3α process reaction rate calculations haveto be accordingly revised.