Potential experimental evidence of an Efimov state in ¹²C and its influence on astrophysical carbon creation

¹ INFN Sezione di Catania, Italy
² INFNLaboratori Nazionali del Sud, Catania, Italy
³ Cyclotron Institute Texas AM University college station, USA
⁴ Dip. di Fisica e Astr. “Ettore Majorana”, Università degli Studi di Catania, Italy
⁵ DSMISFT Università di Messina, Italy
⁶ DEIB Politecnico Milano and INFN Sez. Milano, Italy
⁷ Instituto de Física, Universidad Nacional Autónoma de México

^* e-mail: cardella@ct.infn.it

Published online: 22 March 2023

Abstract

We describe the search of the Efimov state in ¹²C performed by analysing a large set of 3-α particles coincidence data measured at the LNS laboratories with the CHIMERA detector. The data are compatible with the presence of an Efimov state at the excitation energy of 7.485 MeV, with an excitation probability smaller than 0.3% of the population probability of the Hoyle state. The Efimov state gamma decay probability should be around 30%, much larger than the one of the Hoyle state. The population of this level is compatible with the Suda limit for the 3-α reaction rate in stars because its population should be possible only through direct 3-α reaction. More investigations improving the detector angular resolution are needed to confirm these preliminary observations.