Neutron-upscattering enhancement of the triple-alpha process

J. Bishop, C. E. Parker, G. V. Rogachev, S. Ahn, E. Koshchiy, K. Brandenburg, C. R. Brune, R. J. Charity, J. Derkin, N. Dronchi, G. Hamad, Y. Jones-alberty, Tz. Kokalova, T. N. Massey, Z. Meisel, E. V. Ohstrom, S. N. Paneru, E. C. Pollacco, M. Saxena, N. SinghR. Smith, L. G. Sobotka, D. Soltesz, S. K. Subedi, A. V. Voinov, J. Warren, C. Wheldon

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The neutron inelastic scattering of carbon-12, populating the Hoyle state, is a reaction of interest for the triple-alpha process. The inverse process (neutron upscattering) can enhance the Hoyle state’s decay rate to the bound states of 12C, effectively increasing the overall triple-alpha reaction rate. The cross section of this reaction is impossible to measure experimentally but has been determined here at astrophysically-relevant energies using detailed balance. Using a highly-collimated monoenergetic beam, here we measure neutrons incident on the Texas Active Target Time Projection Chamber (TexAT TPC) filled with CO2 gas, we measure the 3α-particles (arising from the decay of the Hoyle state following inelastic scattering) and a cross section is extracted. Here we show the neutron-upscattering enhancement is observed to be much smaller than previously expected. The importance of the neutron-upscattering enhancement may therefore not be significant aside from in very particular astrophysical sites (e.g. neutron star mergers).
Original languageEnglish
Article number2151
Number of pages5
JournalNature Communications
Issue number1
Early online date20 Apr 2022
Publication statusPublished - Dec 2022

Bibliographical note

Funding Information:
This work was supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Science (under awards no. DE-FG02-93ER40773 (J.B., G.V.R., S.A., E.K.), DE-FG02-88ER40387 (K.B., C.R.B., G.H., Y.J.A., T.N.M., Z.M., S.P., M.S., N.S., D.S, S.S., A.V.V., J.W.), DE-SC0019042 (Z.M., M.S., N.S., D.S.), DE-NA0003883 (C.R.B., Y.J.A., T.N.M., S.P., J.W.), DE-NA0003909 (K.B., Z.M., A.V.V.), DE-FG02-87ER-40316 (R.J.C., N.D. and L.G.S.), by National Nuclear Security Administration through the Center for Excellence in Nuclear Training and University-Based Research (CENTAUR) under grant number DE-NA0003841 (J.B., C.E.P., G.V.R., S.A., E.K., N.D., E.V.O., L.G.S.) and by the UK STFC Network+ Award Grant number ST/N00244X/1 (Tz.K., R.S., and C.W.). This work also benefited from support by the National Science Foundation under Grant No. PHY-1430152 (JINA Center for the Evolution of the Elements). G.V.R. also acknowledges the support of the Nuclear Solutions Institute.

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© 2022, The Author(s).


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