Resonant excitation of the reaction<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mmultiscripts><mml:mrow><mml:mi mathvariant="normal">Ta</mml:mi></mml:mrow><mml:mrow /><mml:mrow><mml:mi mathvariant="italic">m</mml:mi></mml:mrow><mml:mrow /><mml:mrow /><mml:mprescripts /><mml:mrow /><mml:mrow><mml:mn>180</mml:mn></mml:mrow><mml:mrow /><mml:mrow /></mml:mmultiscripts></mml:mrow></mml:math>(γ,γ’<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"

Collins, C. B.; Carroll, J. J.; Sinor, T. W.; Byrd, Matthew J.; Richmond, D.; Taylor, K. N.; Hüber, M.; Huxel, N.; Neumann‐Cosel, P. von; Richter, A.; Spieler, C.; Ziegler, W.

doi:10.1103/physrevc.42.r1813

Cited by 66 publications

(25 citation statements)

References 9 publications

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“…The s-process production of 180 Ta depends on the neutron capture cross sections of 179 Ta [7] and 180 Ta [14,15,16] and the photodestruction of the 9 − isomeric state in 180 Ta which has been studied using real photons from bremsstrahlung and from radioactive sources and virtual photons in Coulomb excitation experiments [17,18,19,20,21,22,23,24,25,26,27,28,29,30]. It is the scope of the present paper to improve the analysis of the above experimental data and to calculate the effective half-life of 180 Ta under s-process conditions and the survival probability of 180 Ta in supernova explosions after production by photon-and neutrino-induced reactions.…”

mentioning

confidence: 99%

Survival of nature's rarest isotopeTa180under stellar conditions

Mohr

Käppeler²,

Gallino

2007

Phys. Rev. C

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The nucleosynthesis of nature's rarest isotope 180 Ta depends sensitively on the temperature of the astrophysical environment because of depopulation of the long-living isomeric state via intermediate states to the short-living ground state by thermal photons. Reaction rates for this transition have been measured in the laboratory. These ground state rates understimate the stellar rates dramatically because under stellar conditions intermediate states are mainly populated by excitations from thermally excited states in 180m Ta. Full thermalization of 180 Ta is already achieved for typical s-process temperatures around kT = 25 keV. Consequently, for the survival of 180 Ta in the s-process fast convective mixing is required which has to transport freshly synthesized 180 Ta to cooler regions. In supernova explosions 180 Ta is synthesized by photon-or neutrino-induced reactions at temperatures above T9 = 1 in thermal equilibrium; independent of the production mechanism, freeze-out from thermal equilibrium occurs at kT ≈ 40 keV, and only 35 ± 4 % of the synthesized 180 Ta survive in the isomeric state.

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mentioning

confidence: 99%

Survival of nature's rarest isotopeTa180under stellar conditions

Mohr

Käppeler²,

Gallino

2007

Phys. Rev. C

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“…There is indirect confirmation for the existence of IMS which couple the low-K ground state and the high-K isomeric state from photoactivation experiments (Belic et al, 2002;Collins et al, 1990). However, no direct -transition has been observed up to now.…”

Section: Ta and Its Uncertain Nucleosynthetic Originmentioning

confidence: 84%

Nuclear Excitation Processes in Astrophysical Plasmas

Gosselin¹,

Mohr²,

Méot³

et al. 2012

Astrophysics

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“…A review of the results for 176 Lu is given in [5]. For 180 Ta only indirect evidence for the existence of IMS was derived from photoactivation [27][28][29][30][31][32][33][34][35][36][37][38][39][40]. A direct detection of IMS by γ-spectroscopy was not possible up to now, see e.g.…”

Section: Stellar Reaction Ratesmentioning

confidence: 99%

Modification of nuclear transitions in stellar plasma by electronic processes:Kisomers inLu176and
Gosselin¹,
Morel²,
Mohr³
2010
Phys. Rev. C
13
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16
0
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The influence of the stellar plasma on the production and destruction of K-isomers is studied for the examples 176 Lu and 180 Ta. Individual electromagnetic transitions are enhanced predominantly by nuclear excitation by electron capture, whereas the other mechanisms of electron scattering and nuclear excitation by electron transition give only minor contributions. It is found that individual transitions can be enhanced significantly for low transition energies below 100 keV. Transitions with higher energies above 200 keV are practically not affected. Although one low-energy transition in 180 Ta is enhanced by up to a factor of 10, the stellar transition rates from low-K to high-K states via so-called intermediate states in176 Lu and 180 Ta do not change significantly under s-process conditions. The s-process nucleosynthesis of 176 Lu and 180 Ta remains essentially unchanged.

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Resonant excitation of the reactionTam180(γ,γ’

Cited by 66 publications

References 9 publications

Survival of nature's rarest isotopeTa180under stellar conditions

Survival of nature's rarest isotopeTa180under stellar conditions

Nuclear Excitation Processes in Astrophysical Plasmas

Modification of nuclear transitions in stellar plasma by electronic processes:Kisomers inLu176and
Gosselin¹,
Morel²,
Mohr³
2010
Phys. Rev. C
13
0
16
0
View full text Add to dashboard Cite

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Resonant excitation of the reactionTam180(γ,γ’

Cited by 66 publications

References 9 publications

Survival of nature's rarest isotopeTa180under stellar conditions

Survival of nature's rarest isotopeTa180under stellar conditions

Nuclear Excitation Processes in Astrophysical Plasmas

Modification of nuclear transitions in stellar plasma by electronic processes:Kisomers inLu176andGosselin1, Morel2, Mohr3 2010Phys. Rev. C130160View full textAdd to dashboardCite

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Modification of nuclear transitions in stellar plasma by electronic processes:Kisomers inLu176and
Gosselin¹,
Morel²,
Mohr³
2010
Phys. Rev. C
13
0
16
0
View full text Add to dashboard Cite