First measurement of 87Rb(α, xn) cross sections at weak r-process energies in supernova ν-driven ejecta to investigate elemental abundances in low-metallicity stars
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2025
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| author | Fougères, C. Avila, M. L. Psaltis, A. Anastasiou, M. Bae, S. Balliet, L. Bhatt, K. Dienis, L. Jayatissa, H. Karayonchev, V. Mohr, P. Montes, F. Neto, D. Santos, F. de Oliveira Ong, W. -J. Rehm, K. E. Reviol, W. Santiago-Gonzalez, D. Sensharma, N. Sidhu, R. S. Tolstukhin, I. A. |
| author_facet | Fougères, C. Avila, M. L. Psaltis, A. Anastasiou, M. Bae, S. Balliet, L. Bhatt, K. Dienis, L. Jayatissa, H. Karayonchev, V. Mohr, P. Montes, F. Neto, D. Santos, F. de Oliveira Ong, W. -J. Rehm, K. E. Reviol, W. Santiago-Gonzalez, D. Sensharma, N. Sidhu, R. S. Tolstukhin, I. A. |
| contents | Observed abundances of Z ~ 40 elements in metal-poor stars vary from star to star, indicating that the rapid and slow neutron capture processes may not contribute alone to the synthesis of elements beyond iron. The weak r-process was proposed to produce Z ~ 40 elements in a subset of old stars. Thought to occur in the ν-driven ejecta of a core-collapse supernova, (α, xn) reactions would drive the nuclear flow toward heavier masses at T = 2-5 GK. However, current comparisons between modelled and observed yields do not bring satisfactory insights into the stellar environment, mainly due to the uncertainties of the nuclear physics inputs where the dispersion in a given reaction rate often exceeds one order of magnitude. Involved rates are calculated with the statistical model where the choice of an α-optical-model potential (αOMP) leads to such a poor precision. The first experiment on 87Rb(α, xn) reactions at weak r-process energies is reported here. Total inclusive cross sections were assessed at Ec.m. = 8.1 - 13 MeV (3.7 - 7.6 GK) with the active target MUlti-Sampling Ionization Chamber (MUSIC). With a N = 50 seed nucleus, the measured values agree with statistical model estimates using the αOMP Atomki-V2. A re-evaluated reaction rate was incorporated into new nucleosynthesis calculations, focusing on ν-driven ejecta conditions known to be sensitive to this specific rate. These conditions were found to fail to reproduce the lighter-heavy element abundances in metal-poor stars. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2502_10808 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | First measurement of 87Rb(α, xn) cross sections at weak r-process energies in supernova ν-driven ejecta to investigate elemental abundances in low-metallicity stars Fougères, C. Avila, M. L. Psaltis, A. Anastasiou, M. Bae, S. Balliet, L. Bhatt, K. Dienis, L. Jayatissa, H. Karayonchev, V. Mohr, P. Montes, F. Neto, D. Santos, F. de Oliveira Ong, W. -J. Rehm, K. E. Reviol, W. Santiago-Gonzalez, D. Sensharma, N. Sidhu, R. S. Tolstukhin, I. A. Nuclear Experiment Observed abundances of Z ~ 40 elements in metal-poor stars vary from star to star, indicating that the rapid and slow neutron capture processes may not contribute alone to the synthesis of elements beyond iron. The weak r-process was proposed to produce Z ~ 40 elements in a subset of old stars. Thought to occur in the ν-driven ejecta of a core-collapse supernova, (α, xn) reactions would drive the nuclear flow toward heavier masses at T = 2-5 GK. However, current comparisons between modelled and observed yields do not bring satisfactory insights into the stellar environment, mainly due to the uncertainties of the nuclear physics inputs where the dispersion in a given reaction rate often exceeds one order of magnitude. Involved rates are calculated with the statistical model where the choice of an α-optical-model potential (αOMP) leads to such a poor precision. The first experiment on 87Rb(α, xn) reactions at weak r-process energies is reported here. Total inclusive cross sections were assessed at Ec.m. = 8.1 - 13 MeV (3.7 - 7.6 GK) with the active target MUlti-Sampling Ionization Chamber (MUSIC). With a N = 50 seed nucleus, the measured values agree with statistical model estimates using the αOMP Atomki-V2. A re-evaluated reaction rate was incorporated into new nucleosynthesis calculations, focusing on ν-driven ejecta conditions known to be sensitive to this specific rate. These conditions were found to fail to reproduce the lighter-heavy element abundances in metal-poor stars. |
| title | First measurement of 87Rb(α, xn) cross sections at weak r-process energies in supernova ν-driven ejecta to investigate elemental abundances in low-metallicity stars |
| topic | Nuclear Experiment |
| url | https://arxiv.org/abs/2502.10808 |