Measurement of the 13C(n,γ)14C cross section at stellar energies

Shima, T.; Okazaki, Fumiaki; Kikuchi, Takashi; Kobayashi, T.; Kii, Toshiteru; Baba, T.; Nagai, Y.; Igashira, M.

doi:10.1016/s0375-9474(97)00243-1

Cited by 17 publications

(28 citation statements)

References 7 publications

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“…Fig. 6 shows that the results of the AMS measurement at 25 keV are in fair agreement with the previous experimental [51,52] and theoretical [50] data, but about two times higher than the JEFF-3.1 evaluation. For the two higher neutron energies a striking discrepancy was found with respect to the strength of the 143 keV resonance, which turned out to be a factor of 10 lower than the calculation of Herndl et al [50] (indicated by the horizontal bars in Fig.…”

Section: C: a Potential Neutron Poisonsupporting

confidence: 83%

“…At temperatures above T 8 = 3 the reaction rate is dominated by the 143 keV resonance, at lower temperatures by the p-wave and s-wave contributions. The calculations [50] are in reasonable agreement with two previous experiments [51,52], but exhibit a significant discrepancy compared to the most recent evaluation of JEFF-3.1, which is consistently higher than the calculation, culminating in a 25 times higher peak value for the 143 keV resonance.…”

Section: C: a Potential Neutron Poisonsupporting

confidence: 77%

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Stellar neutron capture rates – key data for thesprocess

Käppeler

2013

EPJ Web of Conferences

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Abstract. Neutron reactions are responsible for the formation of the elements heavier than iron. The corresponding scenarios relate to the He-and C-burning phases of stellar evolution (s process) and to supernova explosions (r and p processes). The s process, which is characterized by low neutron densities, operates in or near the valley of stability and has produced about half of the elemental abundances between Fe and Bi in the solar system and in the Universe. Because the s abundances are essentially determined by the (n, ) cross sections along the reaction path, accurate neutron data constitute the key input for s process studies. Important constraints for the physical conditions at the stellar sites can be inferred by comparison of the abundance patterns from current s-process models with solar system material or presolar grains. The experimental methods for the determination of stellar (n, ) rates are outlined at the example of recent cross section measurements and remaining quests will be discussed with respect to existing laboratory neutron sources and new developments.

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Section: C: a Potential Neutron Poisonsupporting

confidence: 83%

Section: C: a Potential Neutron Poisonsupporting

confidence: 77%

Stellar neutron capture rates – key data for thesprocess

Käppeler

2013

EPJ Web of Conferences

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“…At temperatures above 0.3 GK the reaction rate is dominated by the 143 keV resonance, at lower temperatures p-wave and s-wave contributions are dominant. The calculations of (Herndl et al 1999) show a satisfactory agreement with two previous experimental data (Shima et al 1997;Raman et al 1990) although the energy dependence of the cross section is somewhat different. A significant discrepancy is found if the calculations of Herndl et al are compared to the most recent evaluation of JEFF-3.1 (¼ EAF2003) which suggests at the resonance a cross section value 25 times higher than calculated by Herndl et al…”

Section: C(ng) 14 Csupporting

confidence: 83%

AMS Applications in Nuclear Astrophysics: New Results for ¹³C(n,γ) ¹⁴C and ¹⁴N(n,p) ¹⁴C

Wallner

Buczak

Dillmann

et al. 2012

Publ. – Astron. Soc. Aust

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Abstract:The technique of accelerator mass spectrometry (AMS) offers a complementary tool for studying long-lived radionuclides in nuclear astrophysics: (1) as a tool for investigating nucleosynthesis in the laboratory; and (2) via a direct search of live long-lived radionuclides in terrestrial archives as signatures of recent nearby supernova-events. A key ingredient to our understanding of nucleosynthesis is accurate crosssection data. AMS was applied for measurements of the neutron-induced cross sections 13 C(n,g) and 14 N(n,p), both leading to the long-lived radionuclide 14 C. Solid samples were irradiated at Karlsruhe Institute of Technology with neutrons closely resembling a Maxwell-Boltzmann distribution for kT ¼ 25 keV, and with neutrons of energies between 123 and 178 keV.

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“…Experimental data in the keV region are scarce for this reaction. First results by Raman et al [7] were consolidated by Shima et al [8], providing values for E n = 25.1, 40, and 61.1 keV (see also Fig. 7).…”

mentioning

confidence: 85%

“…So far, this reaction as well as the 13 C(n,γ ) reaction are poorly known. Therefore, activation studies were performed using well-defined neutron fields and subsequent accelerator mass spectrometry (AMS) for sensitive cross section measurements for the 13 C(n,γ ) channel, targeting discrepancies at kT = 25 keV between the two existing experiments [7,8] and theoretical work [9]. We also provide first experimental results at higher energies as well as improve the information on the 14 N(n,p) reaction.…”

mentioning

confidence: 99%

Accelerator mass spectrometry measurements of theC13(n,γ)C14and
Wallner
¹
,
Bichler
²
,
Buczak
³

et al. 2016
Phys. Rev. C
28
1
17
0
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The technique of accelerator mass spectrometry (AMS), offering a complementary tool for sensitive studies of key reactions in nuclear astrophysics, was applied for measurements of the 13 C(n,γ ) 14 C and the 14 N(n,p) 14 C cross sections, which act as a neutron poison in s-process nucleosynthesis. Solid samples were irradiated at Karlsruhe Institute of Technology with neutrons closely resembling a Maxwell-Boltzmann distribution for kT = 25 keV, and also at higher energies between E n = 123 and 182 keV. After neutron irradiation the produced amount of 14 C in the samples was measured by AMS at the Vienna Environmental Research Accelerator (VERA) facility. For both reactions the present results provide important improvements compared to previous experimental data, which were strongly discordant in the astrophysically relevant energy range and missing for the comparably strong resonances above 100 keV. For 13 C(n,γ ) we find a four times smaller cross section around kT = 25 keV than a previous measurement. For 14 N(n,p), the present data suggest two times lower cross sections between 100 and 200 keV than had been obtained in previous experiments and data evaluations. The effect of the new stellar cross sections on the s process in low-mass asymptotic giant branch stars was studied for stellar models of 2 M initial mass, and solar and 1/10 th solar metallicity.

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Measurement of the 13C(n,γ)14C cross section at stellar energies

Cited by 17 publications

References 7 publications

Stellar neutron capture rates – key data for thesprocess

Stellar neutron capture rates – key data for thesprocess

AMS Applications in Nuclear Astrophysics: New Results for ¹³C(n,γ) ¹⁴C and ¹⁴N(n,p) ¹⁴C

Accelerator mass spectrometry measurements of theC13(n,γ)C14and
Wallner
¹
,
Bichler
²
,
Buczak
³

et al. 2016
Phys. Rev. C
28
1
17
0
View full text Add to dashboard Cite

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Measurement of the 13C(n,γ)14C cross section at stellar energies

Cited by 17 publications

References 7 publications

Stellar neutron capture rates – key data for thesprocess

Stellar neutron capture rates – key data for thesprocess

AMS Applications in Nuclear Astrophysics: New Results for 13C(n,γ) 14C and 14N(n,p) 14C

Accelerator mass spectrometry measurements of theC13(n,γ)C14andWallner1, Bichler2, Buczak3 et al. 2016Phys. Rev. C281170View full textAdd to dashboardCite

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AMS Applications in Nuclear Astrophysics: New Results for ¹³C(n,γ) ¹⁴C and ¹⁴N(n,p) ¹⁴C

Accelerator mass spectrometry measurements of theC13(n,γ)C14and
Wallner
¹
,
Bichler
²
,
Buczak
³

et al. 2016
Phys. Rev. C
28
1
17
0
View full text Add to dashboard Cite