A Study of the Interaction of Protons with Tritium

Taschek, R. F.; Jarvis, G. A.; Hemmendinger, A.; Everhart, G.G.; Gittings, H.T.

doi:10.1103/physrev.75.1361

Cited by 21 publications

(7 citation statements)

References 9 publications

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“…The results of Argo 17 and Taschek 16 in the energy region i^>150 kev have been smoothly joined to Bonner's results for E d < 133 kev. It is clear from this figure that deuteron energies much less than 50 kev do not make any significant contribution to the total cross section.…”

Section: Posssalant Snow and Yuansupporting

confidence: 59%

“…For this same range of deuteron energies, Allan and Poole 15 have shown that the angular distribution of the alpha-particles (and hence of the neutrons) is symmetric in the center-of-mass system. Taschek et al 16 have measured the cross section as a function of angle for 1-Mev to 2.5-Mev deuterons impinging on gaseous tritium. They find the total cross section to be about 0.15 barn, and a distinct asymmetry in the angular distribution in the center-of-mass system that essentially increases with energy.…”

Section: Oxygen and Nitrogenmentioning

confidence: 99%

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Total Cross Sections for 14-Mev Neutrons

et al. 1952

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Section: Posssalant Snow and Yuansupporting

confidence: 59%

Section: Oxygen and Nitrogenmentioning

confidence: 99%

Total Cross Sections for 14-Mev Neutrons

et al. 1952

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“…The former are direct measurements of the forward reaction, while the latter are from the reverse reaction, but we are not aware of JCAP03(2020)010 7 Be(n, p) [54]. Measurements from inverse kinematics are from Sekharan [55], Gibbons [56], and Taschek [57], and are transformed using detailed balance. Note the resonances around 0.32 and 2.7 MeV; also note the discrepancies in the normalization at low energies.…”

Section: Reactionmentioning

confidence: 99%

Big-Bang Nucleosynthesis after Planck

Fields

Olive

Yeh

et al. 2020

J. Cosmol. Astropart. Phys.

362

320

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We assess the status of big-bang nucleosynthesis (BBN) in light of the final Planck data release and other recent developments, and in anticipation of future measurements. Planck data from the recombination era fix the cosmic baryon density to 0.9% precision, and now damping tail measurements determine the helium abundance and effective number of neutrinos with precision approaching that of astronomical and BBN determinations respectively. All three parameters are related by BBN. In addition, new high-redshift measurements give D/H to better precision than theoretical predictions, and new Li/H data reconfirm the lithium problem. We present new 7 Be(n, p) 7 Li rates using new neutron capture measurements; we have also examined the effect of proposed changes in the d(p, γ) 3 He rates. Using these results we perform a series of likelihood analyses. We assess BBN/CMB consistency, with attention to how our results depend on the choice of Planck data, as well as how the results depend on the choice of non-BBN, non-Planck data sets. Most importantly the lithium problem remains, and indeed is more acute given the very tight D/H observational constraints; new neutron capture data reveals systematics that somewhat increases uncertainty and thus slightly reduces but does not essentially change the problem. We confirm that d(p, γ) 3 He theoretical rates brings D/H out of agreement and slightly increases 7 Li; new experimental data are needed at BBN energies. Setting the lithium problem aside, we find the effective number of neutrino species at BBN is N ν = 2.86±0.15. Future CMB Stage-4 measurements promise substantial improvements in BBN parameters: helium abundance determinations will be competitive with the best astronomical determinations, and N eff will approach sensitivities capable of detecting the effects of Standard Model neutrino heating of the primordial plasma. 7 Li(p, α) 4 He 7 Li(p, γ) 4 He 4 He Also following [29], we model the uncertainty distribution as a lognormal distribution.This is motivated physically by the idea that the experimental nuclear rates are controlled by several multiplicative factors whose uncertainties thus take this form [17]. In practice the errors are usually sufficiently small that the choice of a lognormal versus Gaussian distribution does not have a large impact on our result.

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“…Until few years ago the main method for producing 7 Be was by proton irradiation of 7 Li. However, the low cross section of this nuclear reaction (0.5 barn in the maximum of the excitation function at 2250 keV [22,23]) implies irradiation time of several weeks to obtain the required amount of 7 Be, making this route very expensive. In addition, difficult chemical processes must adopted to separate the obtained microscopic amounts of 7 Be from the macroscopic amount of 7 Li.…”

Section: Jinst 12 P02016mentioning

confidence: 99%

“…7 Be, in this case, is extracted using an ion exchanger filter from the cooling water (ultrapure D 2 O) of the Spallation Induced Neutron Source (SINQ) facility at PSI, where it is produced (together with 9 Be and 10 Be) by spallation reactions on 16 O. Subsequently, it is chromatographically separated from other cations, of similar quantities, trapped in the filter, such as, 7 Li, 3 H, 22 Na, 88 Y and 110m Ag. This method allows obtaining hundreds of GBq of chemically pure 7 Be without additional costs for dedicated irradiations.…”

Section: Jinst 12 P02016mentioning

confidence: 99%