A new high-precision upper limit of direct α-decays from the Hoyle state in 12C

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

doi:10.1051/epjconf/201716501020

Proceedings

Open Access

EPJ Web of Conferences 165, 01020 (2017)
https://doi.org/10.1051/epjconf/201716501020

A new high-precision upper limit of direct α-decays from the Hoyle state in ¹²C

D. Dell’Aquila¹^,2^,3^*, I. Lombardo⁴, G. Verde³^,4, M. Vigilante¹^,2, L. Acosta⁵, C. Agodi⁶, F. Cappuzzello⁷^,6, D. Carbone⁶, M. Cavallaro⁶, S. Cherubini⁶^,7, A. Cvetinovic⁶, G. D’Agata⁷^,6, L. Francalanza², G.L. Guardo⁶, M. Gulino⁶^,6, I. Indelicato⁶, M. La Cognata⁶, L. Lamia⁷, A. Ordine², R.G. Pizzone⁶, S.M.R. Puglia⁶, G.G. Rapisarda⁶, S. Romano⁶, G. Santagati⁶, R. Spartà⁶, G. Spadaccini¹^,2, C. Spitaleri⁷^,6 and A. Tumino⁸^,6

¹ Dip. di Fisica “E. Pancini”, Università di Napoli Federico II, I-80126 Napoli, Italy
² INFN-Sezione di Napoli, I-80126 Napoli, Italy
³ Institut de Physique Nucléaire, CNRS-IN2P3, Univ. Paris-Sud, Université Paris-Saclay, 91406 Orsay Cedex, France
⁴ INFN - Sezione di Catania, Via S. Sofia, I-95125 Catania, Italy
⁵ Universidad Nacional Autónoma de México, A.P. 20-364, Cd.Mx, D.F. 01000 México
⁶ INFN - Laboratori Nazionali del Sud, Via S. Sofia, I-95125 Catania, Italy
⁷ Dip. di Fisica e Astronomia, Università di Catania, Via S. Sofia, I-95125 Catania, Italy
⁸ Facoltà di Ingegneria ed Architettura, Università Kore, I-94100 Enna, Italy

^* e-mail: dellaquila@na.infn.it

Published online: 30 December 2017

Abstract

The Hoyle state in ¹²C(E_x = 7.654MeV) is characterized by a pronounced 3α cluster configuration. It is involved in the so-called 3α process in stars, that is responsible of ¹²C nucleosynthesis. We studied the decay path of the Hoyle state by using the ¹⁴N(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 of ⁸Be. 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.

© The Authors, published by EDP Sciences, 2017

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