dorsal/arxiv
View SchemaReaction rate for two--neutron capture by $^4$He
| Authors | V. D. Efros, W. Balogh, H. Herndl, R. Hofinger, H. Oberhummer |
|---|---|
| Categories | |
| ArXiv ID | nucl-th/9602033 |
| URL | https://arxiv.org/abs/nucl-th/9602033 |
| DOI | 10.1007/s002180050084 |
Abstract
Recent investigations suggest that the neutrino--heated hot bubble between the nascent neutron star and the overlying stellar mantle of a type--II supernova may be the site of the r--process. In the preceding $\alpha$--process building up the elements to $A \approx 100$, the $^4$He(2n,$\gamma$)$^6$He-- and $^6$He($\alpha$,n)$^9$Be--reactions bridging the instability gap at $A=5$ and $A=8$ could be of relevance. We suggest a mechanism for $^4$He(2n,$\gamma$)$^6$He and calculate the reaction rate within the $\alpha$+n+n approach. The value obtained is about a factor 1.6 smaller than the one obtained recently in the simpler direct--capture model, but is at least three order of magnitude enhanced compared to the previously adopted value. Our calculation confirms the result of the direct--capture calculation that under representative conditions in the $\alpha$--process the reaction path proceeding through $^6$He is negligible compared to $^4$He($\alpha$n,$\gamma$)$^9$Be.
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"abstract": "Recent investigations suggest that the neutrino--heated hot bubble between\nthe nascent neutron star and the overlying stellar mantle of a type--II\nsupernova may be the site of the r--process. In the preceding $\\alpha$--process\nbuilding up the elements to $A \\approx 100$, the $^4$He(2n,$\\gamma$)$^6$He--\nand $^6$He($\\alpha$,n)$^9$Be--reactions bridging the instability gap at $A=5$\nand $A=8$ could be of relevance. We suggest a mechanism for\n$^4$He(2n,$\\gamma$)$^6$He and calculate the reaction rate within the\n$\\alpha$+n+n approach. The value obtained is about a factor 1.6 smaller than\nthe one obtained recently in the simpler direct--capture model, but is at least\nthree order of magnitude enhanced compared to the previously adopted value. Our\ncalculation confirms the result of the direct--capture calculation that under\nrepresentative conditions in the $\\alpha$--process the reaction path proceeding\nthrough $^6$He is negligible compared to $^4$He($\\alpha$n,$\\gamma$)$^9$Be.",
"arxiv_id": "nucl-th/9602033",
"authors": [
"V. D. Efros",
"W. Balogh",
"H. Herndl",
"R. Hofinger",
"H. Oberhummer"
],
"categories": [
"nucl-th",
"astro-ph"
],
"doi": "10.1007/s002180050084",
"title": "Reaction rate for two--neutron capture by $^4$He",
"url": "https://arxiv.org/abs/nucl-th/9602033"
},
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