Naslov
Experimental investigation of α condensation in light nuclei

Autori
Bishop, J. ; Kokalova, Tz. ; Freer, M. ; Acosta, L. ; Assié, M. ; Bailey, S. ; Cardella, G. ; Curtis, N. ; De Filippo, E. ; Dell'Aquila, Daniele ; De Luca, S. ; Francalanza, L. ; Gnoffo, B. ; Lanzalone, G. ; Lombardo, I. ; Martorana, N. S. ; Norella, S. ; Pagano, A. ; Pagano, E. V. ; Papa, M. ; Pirrone, S. ; Politi, G. ; Rizzo, F. ; Russotto, P. ; Quattrocchi, L. ; Smith, R. ; Stefan, I. ; Trifirò, A. ; Trimarchì, M. ; Verde, G. ; Vigilante, M. ; Wheldon, C.

Izvornik
Physical review. C (2469-9985) 100 (2019), 3; 034320, 20

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
Nuclear Structure ; Nuclear Clustering ; Light nuclei

Sažetak
Background: Near-threshold α-clustered states in light nuclei have been postulated to have a structure consisting of a diffuse gas of α particles which condense into the 0s orbital. Experimental evidence for such a dramatic phase change in the structure of the nucleus has not yet been observed. Purpose: To understand the role of α condensation in light nuclei experimentally. Method: To examine signatures of this α condensation, a compound nucleus reaction using 160-, 280-, and 400-MeV O16 beams impinging on a carbon target was used to investigate the C12(O16, 7α) reaction. This permits a search for near-threshold states in the α-conjugate nuclei up to Mg24. Results: Events up to an α-particle multiplicity of seven were measured and the results were compared to both an extended Hauser- Feshbach calculation and the Fermi breakup model. The measured multiplicity distribution exceeded that predicted from a sequential decay mechanism and had a better agreement with the multiparticle Fermi breakup model. Examination of how these 7α final states could be reconstructed to form Be8 and C12(02+) showed a quantitative difference in which decay modes were dominant compared to the Fermi breakup model. No new states were observed in O16, Ne20, and Mg24 due to the effect of the N-α penetrability suppressing the total α- particle dissociation decay mode. Conclusion: The reaction mechanism for a high-energy compound nucleus reaction can only be described by a hybrid of sequential decay and multiparticle breakup. Highly α-clustered states were seen which did not originate from simple binary reaction processes. Direct investigations of near-threshold states in N-α systems are inherently impeded by the Coulomb barrier prohibiting the observation of states in the N-α decay channel. No evidence of a highly clustered 15.1-MeV state in O16 was observed from [Si- 28, C12(02+)]O16(06+) when reconstructing the Hoyle state from three α particles. Therefore, no experimental signatures for α condensation were observed.

Izvorni jezik
Engleski

Znanstvena područja
Fizika

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