Indirect investigation of proton capture reactions at stellar energies

Schmalbrock, Petra; Donoghue, T.R.; Hausman, H.J.; Wiescher, M.; Wijekumar, V.; Browne, C.P.; Rollefson, A.A.; Rolfs, C.

doi:10.1063/1.35143

Cited by 5 publications

(11 citation statements)

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“…However, the small feature less cross sections observed in the present experiment is consistent with an excited-corecoupled state for a state of J~ = (7/2,9/2) + in this mass region. However, a possible state at around 7.643 MeV was suggested only by the (3He,a) reaction [3], although there was no spin assignment.…”

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confidence: 96%

“…The nucleus 22Na, which has a long half-life time of 2.6 y, would have beta decayed afterward, giving a strong enrichment of 22Ne in the meteorites. Thus, the nuclear astrophysical problem here is to know the reaction rates which are associated with 22Na [1][2][3].The main production processes of 22Na would be 21Ne(p,~/) and 22Mg(l~+v ), and they are known rather well. However, the destruction process, 22Na(p,,f)23Mg, was not well studied.…”

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confidence: 99%

“…For the 7.624 MeV state the fit to the angular distribution is not so good, which is obtained by assuming Jg = (7/2,9/2) +, the value obtained by the reactions 25Mg(p,t) [8], 24Mg(p,d) [13], and 24Mg(3He,ot) [3]. However, the small feature less cross sections observed in the present experiment is consistent with an excited-corecoupled state for a state of J~ = (7/2,9/2) + in this mass region.…”

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confidence: 99%

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High resolution study of24Mg(p, d)23Mg for the Ne-E problem

Kubono

Yun

Boyd

et al. 1994

Z. Physik A - Hadrons and Nuclei

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Nuclear levels of 23Mg near and above the proton threshold were investigated with high resolution. A new level has been identified at 7.643 MeV (66 keV above the proton threshold) with a possible jn = (3/2, 5/2) +. Some other spin-parity and excitation-energy assignments are also made. These results enable the reaction rate estimate of 22Na(p,7)23Mg with much smaller uncertainties, which is critical for the Ne-E problem in nuclear astrophysics. PACS: 27.30.+t, 97.10.Cv, 97.10.Tk, 97.30.Qt, 98.58.Ca One of the interesting subjects in nuclear astrophysics is the so called Ne-E problem [1], where very high 22Ne enrichments were observed in some meteorites. The most plausible explanation is that the meteorites were produced from the ejecta of some stellar event with high temperatures. The nucleus 22Na, which has a long half-life time of 2.6 y, would have beta decayed afterward, giving a strong enrichment of 22Ne in the meteorites. Thus, the nuclear astrophysical problem here is to know the reaction rates which are associated with 22Na [1][2][3].The main production processes of 22Na would be 21Ne(p,~/) and 22Mg(l~+v ), and they are known rather well. However, the destruction process, 22Na(p,,f)23Mg, was not well studied. Above 290 keV this reaction was investigated by using a radioactive target of 22Na [4,5]. Nevertheless, the reaction rate had a very large uncertainty, several orders of magnitudes, especially at low temperatures [2].We report here the result of a high resolution study of the 24Mg(p,d)23Mg reaction to learn about the nuclear levels (excitation energy and spin-parity) near and just above the proton threshold in 23Mg. A doublet suggested before [3] at 7.63 MeV was resolved experimentally and studied separately.The experiment was performed with a 34.945 MeV proton beam from the sector-focusing cyclotron of the Institute for Nuclear Study, University of Tokyo. The reaction products were momentum analyzed by a high resolution magnetic spectrograph [6], and detected by a hybrid type gas-proportional counter [7] backed up with a plastic scintillator. A metallic foil of 24Mg (enriched to more than 99.9 %) of about 130 gg/cm 2 was used to separate the doublet at around 7.63 MeV in 23Mg: The excitation energy 5~

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confidence: 96%

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confidence: 99%

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confidence: 99%

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High resolution study of24Mg(p, d)23Mg for the Ne-E problem

Kubono

Yun

Boyd

et al. 1994

Z. Physik A - Hadrons and Nuclei

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“…A recent 24Mg(3He, e)Z3Mg experiment [9] as well as studies of the 25Mg(p, t)23Mg reaction [12] and of the 24Mg(p,d)23Mg [13] reaction show evidence for a level in a3Mg at Ex=7.587MeV and a possible doublet structure around Ex=7.635MeV. All these states are just above the proton threshold and have not been considered in the previous estimates of the 22Na(p,y)Z3Mg reaction rate.…”

Section: The 2zna(p ~)Z3mg Ratementioning

confidence: 99%

“…Wiescher et al [4] estimated the rate on the basis of nine /2Na+p resonances recently found in the 24Mg(3He, c023Mg reaction [9]. They calculated the resonance strengths of these states from y-widths which they derived from statistics of y-ray transitions [-8] and from proton widths evaluated using Eq.…”

Section: The 2zna(p ~)Z3mg Ratementioning

confidence: 99%

The proton capture reactions on21Na and22Na under hydrogen burning conditions

Wiescher

Langanke

1986

Z. Physik A - Atomic Nuclei

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We have updated and recalculated the ZlNa(p,T)ZZMg and 22Na(p, 7)Z3Mg reaction rates for temperatures 107-109K relevant for explosive hydrogen burning in stellar environment. We find the 21Na(p, 7)ZZMg rate lower than recently suggested. Considering various uncertainties in spin and parity assignments of the low energy ZeNa+p resonances we present upper and lower limits for the 22Na(p, 7)23Mg reaction rate which, however, allows for a meaningful discussion of the consequences of the new rates on the Ne-Na cycle under various stellar conditions.

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