Signals of Bose Einstein condensation and Fermi quenching in the decay of hot nuclear systems

Marini, P.; Zheng, H.; Boisjoli, M.; Verde, G.; Chbihi, A.; Napolitani, P.; Adémard, G.; Augey, L.; Bhattacharya, C.; Borderie, B.; Bougault, R.; Frankland, J.D.; Fable, Q.; Galichet, E.; Gruyer, D.; Kundu, S.; Commara, M. La; Lombardo, I.; Lopez, O.; Mukherjee, G.; Pârlog, M.; Rivet, M. F.; Rosato, E.; Roy, R.; Spadaccini, G.; Vigilante, M.; Wigg, P.; Bonasera, A.

doi:10.1016/j.physletb.2016.02.063

Cited by 22 publications

(20 citation statements)

References 46 publications

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“…If there is no excited level in 12 C at 7.458 MeV, we might still wonder what would happen in a α-burning star if their average relative energies are close to the 8 Be g.s.. Similarly in fragmentation reactions, in the later stages when the density is low and drops start to appear [32][33][34] it is possible that this mechanism of mutual resonances increases the probability of making 12 C even though some extra energy from the surrounding matter has to be provided to populate the Hoyle state (i.e., there is no ES). The other peculiarity of the ES would be the fact that the final energies of the 3αs are equal both for the SD and DD cases, thus they would be experimentally indistinguishable.…”

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Decay modes of the Hoyle state in C12

et al. 2018

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Recent experimental results give an upper limit less than 0.043% (95% C.L.) to the direct decay of the Hoyle state into 3α respect to the sequential decay into 8 Be+α. We performed one and twodimensional tunneling calculations to estimate such a ratio and found it to be more than one order of magnitude smaller than experiment depending on the range of the nuclear force. This is within high statistics experimental capabilities. Our results can also be tested by measuring the decay modes of high excitation energy states of 12 C where the ratio of direct to sequential decay might reach 10% at E * ( 12 C)=10.3 MeV. The link between a Bose Einstein Condensate (BEC) and the direct decay of the Hoyle state is also addressed. We discuss a hypothetical 'Efimov state' at E * ( 12 C)=7.458 MeV, which would mainly sequentially decay with 3α of equal energies: a counterintuitive result of tunneling. Such a state, if it would exist, is at least 8 orders of magnitude less probable than the Hoyle's, thus below the sensitivity of recent and past experiments.

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Decay modes of the Hoyle state in C12

et al. 2018

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“…In Refs. [26][27][28], an analysis was performed for events as in Fig. 3 in terms of Boson-Fermion mixtures, i.e.…”

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Triple α -particle resonances in the decay of hot nuclear systems *

Zhang¹,

Wang²,

Bonasera³

et al. 2019

Chinese Phys. C

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The Efimov (Thomas) trimers in excited 12 C nuclei, for which no observation exists yet, are discussed by means of analyzing the experimental data of 70(64) Zn( 64 Ni) + 70(64) Zn( 64 Ni) reactions at beam energy of E/A=35 MeV/nucleon. In heavy ion collisions, the αs interact with each other and can form complex systems such as 8 Be and 12 C. For the 3α systems, multi resonance processes give rise to excited levels of 12 C. The interaction between any two of the 3α particles provides events with one, two or three 8 Be. Their interfering levels are clearly seen in the minimum relative energy distributions. Events of three couple α relative energies consistent with the ground state of 8 Be are observed with the decrease of the instrumental error at the reconstructed 7.458 MeV excitation energy of 12 C, which was suggested as the Efimov (Thomas) state.

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“…One way to simulate some stellar conditions is to collide two heavy ions at beam energies near the Fermi energy. In central/peripheral collisions of the two ions, first we have a gentle increase in the density slightly above the ground state density, ρ 0 =0.16 f m −3 [17,18] as revealed by microscopic calculations and experiments [19][20][21][22]. The system expands while cooling, and for densities below (1/3-1/6)ρ 0 , clusters start to appear; this is referred to as the freeze-out region.…”

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“…For example, a change in the width of a resonance as compared to the vacuum might tell us the time duration of the freeze-out region. 2) Levels not observed in a vacuum might appear in the surrounding medium, for example, if many αs are formed at relative kinetic energies where E i j =0.092 MeV, then strong resonances among these bosons could give rise to correlations and Bose Einstein Condensation (BEC) [20,24]. These conditions might be identified with the strong resonance region in microscopic calculations of the structure of 12 C [5,21].…”

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Strongly resonating bosons in hot nuclei

et al. 2019

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When two heavy ions near the Fermi energy collide, a warm and low-density region can form in which fragments appear. This region is mainly dominated by proton (p) and alpha (α) particles. In such an environment, the αs interact with each other, and especially through strong resonances, form complex systems such as 8 Be and 12 C. Our experiments show that in the reactions 70(64) Zn( 64 Ni)+ 70(64) Zn( 64 Ni) at E/A=35 MeV/nucleon levels of 8 Be appear around relative energies E i j =0.092 MeV, 3.03 MeV as well as above 10 MeV and 100 MeV. For the 3α systems, multi resonance processes give rise to excited levels of 12 C. In particular, the Hoyle state at 7.654 MeV excitation energy shows a decay component through the ground state of 8 Be and also shows components where two different α couples are at relative energies consistent with the ground state of 8 Be at the same time. A component where the three α relative energies are consistent with the ground state of 8 Be (i.e., E 12 =E 13 =E 23 =0.092 MeV) is also observed at the 7.458 MeV excitation energy, which was suggested as an Efimov state.Several decades after the suggestion by Fred Hoyle [1] of a 0 + resonance near the 3α threshold to accelerate 12 C formation in stars, the Hoyle state (HS) is still a hot topic in nuclear structure [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. While its energy, i.e., 7.654 MeV, and width, 8.5 eV, are firmly established, there are debates on its decay. It is commonly accepted [5][6][7][8][9][10][11][12][13][14][15][16] that almost 100% of the HS decay is through the ground state of 8 Be ( 8 Be g.s. ), thus corresponding to a sequential decay (SD), i.e., first an α particle is emitted, and then 8 Be decays into 2αs with 0.092 MeV relative kinetic energy. Other decay modes, for example, the theoretically predicted direct decay (DD) of 12 C into 3αs of equal energy (DDE) or into a linear chain (LD) [4,5] have been studied in high precision/high statistical experiments [8][9][10][11][12][13][14][15][16] giving an upper limit of 0.043% [14], 0.036%[15] and 0.024%[15] for DD, DDE, and LD, respectively. While we are probably at the limit of the experimental sensitivity, higher statistical experiments might be performed, or different strategies might be explored. In this paper, we will discuss a completely new approach, i.e., we will generally explore the 12 C decays also in the presence of nearby nuclear matter. This is surely relevant since stellar processes, where 12 C (or larger nuclei) are formed, might occur inside a dense star or on its surface, thus occurring under different conditions of density and temperature. One way to simulate some stellar conditions is to collide two heavy ions at beam energies near the Fermi energy. In central/peripheral collisions of the two ions, first we have a gentle increase in the density slightly above the ground state density, ρ 0 =0.16 f m −3 [17,18] as revealed by microscopic calculations and experiments [19][20][21][22]. The system expands while cooling, and for densities below (1/3-1/...

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Signals of Bose Einstein condensation and Fermi quenching in the decay of hot nuclear systems

Cited by 22 publications

References 46 publications

Decay modes of the Hoyle state in C12

Decay modes of the Hoyle state in C12

Triple α -particle resonances in the decay of hot nuclear systems *

Strongly resonating bosons in hot nuclei

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