Precision mass measurements around ${}^{84}$Mo rule out ZrNb cycle formation in the rapid proton-capture process at type I X-ray bursts

Fuente: arXiv
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Main Authors: Kimura, S., Wada, M., Fu, C. Y., Fukuda, N., Hirayama, Y., Hou, D. S., Iimura, S., Ishiyama, H., Ito, Y., Kubono, S., Kusaka, K., Michimasa, S., Miyatake, H., Nishimura, S., Niwase, T., Phong, V., Rosenbusch, M., Schatz, H., Schury, P., Shimizu, Y., Suzuki, H., Takamine, A., Takeda, H., Togano, Y., Watanabe, Y. X., Xian, W. D., Yanagisawa, Y., Yeung, T. T., Yoshimoto, M., Zha, S.
Format: Preprint
Published: 2025
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author Kimura, S.
Wada, M.
Fu, C. Y.
Fukuda, N.
Hirayama, Y.
Hou, D. S.
Iimura, S.
Ishiyama, H.
Ito, Y.
Kubono, S.
Kusaka, K.
Michimasa, S.
Miyatake, H.
Nishimura, S.
Niwase, T.
Phong, V.
Rosenbusch, M.
Schatz, H.
Schury, P.
Shimizu, Y.
Suzuki, H.
Takamine, A.
Takeda, H.
Togano, Y.
Watanabe, Y. X.
Xian, W. D.
Yanagisawa, Y.
Yeung, T. T.
Yoshimoto, M.
Zha, S.
author_facet Kimura, S.
Wada, M.
Fu, C. Y.
Fukuda, N.
Hirayama, Y.
Hou, D. S.
Iimura, S.
Ishiyama, H.
Ito, Y.
Kubono, S.
Kusaka, K.
Michimasa, S.
Miyatake, H.
Nishimura, S.
Niwase, T.
Phong, V.
Rosenbusch, M.
Schatz, H.
Schury, P.
Shimizu, Y.
Suzuki, H.
Takamine, A.
Takeda, H.
Togano, Y.
Watanabe, Y. X.
Xian, W. D.
Yanagisawa, Y.
Yeung, T. T.
Yoshimoto, M.
Zha, S.
contents The rapid proton-capture ($rp$-) process is one of the primary, explosive thermonuclear burning processes that drive type I X-ray bursts. A possible termination of the $rp$-process at around ${}^{84}$Mo was previously suggested by the formation of a ZrNb cycle. We report here precision mass measurements at around ${}^{84}$Mo, which have concluded the possibility of the cycle. The experiment was conducted using the multi-reflection time-of-flight spectrograph at RIKEN RI Beam Factory, and the masses of ${}^{79}$Y, ${}^{83}$Nb, ${}^{84}$Mo, ${}^{88}$Ru, and an isomer in ${}^{78}$Y were measured. For ${}^{84}$Mo, and ${}^{88}$Ru, and the isomeric state of ${}^{78}$Y, their masses are experimentally determined for the first time with uncertainties of $δm \approx 20~{\rm keV/c^2}$. The mass precision of ${}^{79}$Y and ${}^{83}$Nb is improved to $13~{\rm keV/c^2}$ and $9.6~{\rm keV/c^2}$, respectively. The new $α$-separation energy of ${}^{84}$Mo, 1.434(83) MeV, unambiguously rules out the possibility of forming the ZrNb cycle. The X-ray burst simulation with the new masses shows that our measurements effectively remove the large final abundance uncertainties in the $A=80-90$ mass region. The new mass values improve the prediction power for the composition of the nuclear ashes in X-ray bursts.
format Preprint
id arxiv_https___arxiv_org_abs_2504_12639
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Precision mass measurements around ${}^{84}$Mo rule out ZrNb cycle formation in the rapid proton-capture process at type I X-ray bursts
Kimura, S.
Wada, M.
Fu, C. Y.
Fukuda, N.
Hirayama, Y.
Hou, D. S.
Iimura, S.
Ishiyama, H.
Ito, Y.
Kubono, S.
Kusaka, K.
Michimasa, S.
Miyatake, H.
Nishimura, S.
Niwase, T.
Phong, V.
Rosenbusch, M.
Schatz, H.
Schury, P.
Shimizu, Y.
Suzuki, H.
Takamine, A.
Takeda, H.
Togano, Y.
Watanabe, Y. X.
Xian, W. D.
Yanagisawa, Y.
Yeung, T. T.
Yoshimoto, M.
Zha, S.
Nuclear Experiment
High Energy Astrophysical Phenomena
Nuclear Theory
The rapid proton-capture ($rp$-) process is one of the primary, explosive thermonuclear burning processes that drive type I X-ray bursts. A possible termination of the $rp$-process at around ${}^{84}$Mo was previously suggested by the formation of a ZrNb cycle. We report here precision mass measurements at around ${}^{84}$Mo, which have concluded the possibility of the cycle. The experiment was conducted using the multi-reflection time-of-flight spectrograph at RIKEN RI Beam Factory, and the masses of ${}^{79}$Y, ${}^{83}$Nb, ${}^{84}$Mo, ${}^{88}$Ru, and an isomer in ${}^{78}$Y were measured. For ${}^{84}$Mo, and ${}^{88}$Ru, and the isomeric state of ${}^{78}$Y, their masses are experimentally determined for the first time with uncertainties of $δm \approx 20~{\rm keV/c^2}$. The mass precision of ${}^{79}$Y and ${}^{83}$Nb is improved to $13~{\rm keV/c^2}$ and $9.6~{\rm keV/c^2}$, respectively. The new $α$-separation energy of ${}^{84}$Mo, 1.434(83) MeV, unambiguously rules out the possibility of forming the ZrNb cycle. The X-ray burst simulation with the new masses shows that our measurements effectively remove the large final abundance uncertainties in the $A=80-90$ mass region. The new mass values improve the prediction power for the composition of the nuclear ashes in X-ray bursts.
title Precision mass measurements around ${}^{84}$Mo rule out ZrNb cycle formation in the rapid proton-capture process at type I X-ray bursts
topic Nuclear Experiment
High Energy Astrophysical Phenomena
Nuclear Theory
url https://arxiv.org/abs/2504.12639