Photodisintegration of deuterium and big bang nucleosynthesis

Cross sections of the 186 W, 187 Re, 188 Os(γ, n) reactions were measured using quasi-monochromatic photon beams from laser Compton scattering (LCS) with average energies from 7.3 to 10.9 MeV. The results are compared with the predictions of Hauser-Feshbach statistical calculations using four different sets of input parameters. In addition, the inverse neutron capture cross sections were evaluated by constraining the model parameters, especially the E1 strength function, on the basis of the experimental data. The present experiment helps to further constrain the correction factor Fσ for the neutron capture on the 9.75 keV state in 187 Os. Implications of Fσ to the Re-Os cosmochronology are discussed with a focus on the uncertainty in the estimate of the age of the Galaxy.PACS numbers: PACS number(s): 25.40.Lw,26.20.+f

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“…3 of Ref. [25]). The background subtraction is included in the statistical uncertainties through the error propagation.…”

Section: Introductionmentioning

confidence: 88%

Photodisintegration cross section measurements onW186,Re187<

Shizuma¹,

Utsunomiya

Mohr

et al. 2005

Phys. Rev. C

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“…We make use of the following sources: the cross section of Ref. [66] for 2 H, the ab initio calculation [21] for 4 He, and the E1 strength function calculated by the Cb-TDHFB for 12 C. The lower panels of Fig. 5 exhibit the Coulomb breakup cross sections of these targets as a functions of N of the projectile.…”

Section: B Coulomb Breakup Cross Sections By Epmmentioning

confidence: 99%

Extracting nuclear sizes of medium to heavy nuclei from total reaction cross sections

et al. 2016

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Background: Proton and neutron radii are fundamental quantities of atomic nuclei. To study the sizes of short-lived unstable nuclei, there is a need for an alternative to electron scattering. Purpose: The recent paper by Horiuchi et al. [Phys. Rev. C 89, 011601(R) (2014)] proposed a possible way of extracting the matter and neutron-skin thickness of light-to medium-mass nuclei using total reaction cross section, σ R . The analysis is extended to medium to heavy nuclei up to lead isotopes with due attention to Coulomb breakup contributions as well as density distributions improved by paring correlation. Methods:We formulate a quantitative calculation of σ R based on the Glauber model including the Coulomb breakup. To substantiate the treatment of the Coulomb breakup, we also evaluate the Coulomb breakup cross section due to the electric dipole field in a canonical-basis-time-dependent-Hartree-Fock-Bogoliubov theory in the three-dimensional coordinate space. Results: We analyze σ R 's of 103 nuclei with Z = 20, 28, 40, 50, 70, and 82 incident on light targets, 1,2 H, 4 He, and 12 C. Three kinds of Skyrme interactions are tested to generate those wave functions. To discuss possible uncertainty due to the Coulomb breakup, we examine its dependence on the target, the incident energy, and the Skyrme interaction. The proton is a most promising target for extracting the nuclear sizes as the Coulomb excitation can safely be neglected. We find that the so-called reaction radius, a R = √ σ R /π, for the proton target is very well approximated by a linear function of two variables, the matter radius and the skin thickness, in which three constants depend only on the incident energy. We quantify the accuracy of σ R measurements needed to extract the nuclear sizes. Conclusions:The proton is the best target because, once the incident energy is set, its a R is very accurately determined by only the matter radius and neutron-skin thickness. If σ R 's at different incident energies are measured, one can determine both the proton and neutron radii for unstable nuclei as well. The total reaction cross sections calculated in this paper are given as Supplemental Material for the sake of future measurements.

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“…The radiative capture process, np → dγ, plays a critical role in big bang nucleosynthesis (BBN) as it is the starting point for the chain of reactions that form most of the light nuclei in the cosmos. Studies of radiative capture [1][2][3], and the inverse processes of deuteron electro-and photodisintegration, γ ðÃÞ d → np [4][5][6][7], have constrained these cross sections and have also provided critical insights into the interactions between nucleons and photons. They conclusively show the importance of non-nucleonic degrees of freedom in nuclei, which arise from meson-exchange currents (MECs) in the context of nuclear potential models [8,9].…”

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confidence: 99%

Ab initioCalculation of thenp→dγRadiative Capture Process

et al. 2015

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Lattice QCD calculations of two-nucleon systems are used to isolate the short-distance two-body electromagnetic contributions to the radiative capture process np → dγ, and the photo-disintegration processes γ ðÃÞ d → np. In nuclear potential models, such contributions are described by phenomenological meson-exchange currents, while in the present work, they are determined directly from the quark and gluon interactions of QCD. Calculations of neutron-proton energy levels in multiple background magnetic fields are performed at two values of the quark masses, corresponding to pion masses of m π ∼ 450 and 806 MeV, and are combined with pionless nuclear effective field theory to determine the amplitudes for these low-energy inelastic processes. At m π ∼ 806 MeV, using only lattice QCD inputs, a cross section σ 806 MeV ∼ 17 mb is found at an incident neutron speed of v ¼ 2; 200 m=s. Extrapolating the short-distance contribution to the physical pion mass and combining the result with phenomenological scattering information and one-body couplings, a cross section of σ lqcd ðnp → dγÞ ¼ 334.9ð þ5.2 −5.4 Þ mb is obtained at the same incident neutron speed, consistent with the experimental value of σ expt ðnp → dγÞ ¼ 334.2ð0.5Þ mb. The radiative capture process, np → dγ, plays a critical role in big bang nucleosynthesis (BBN) as it is the starting point for the chain of reactions that form most of the light nuclei in the cosmos. Studies of radiative capture [1][2][3], and the inverse processes of deuteron electro-and photodisintegration, γ ðÃÞ d → np [4][5][6][7], have constrained these cross sections and have also provided critical insights into the interactions between nucleons and photons. They conclusively show the importance of non-nucleonic degrees of freedom in nuclei, which arise from meson-exchange currents (MECs) in the context of nuclear potential models [8,9]. Nevertheless, in the energy range relevant for BBN, experimental investigations are challenging [10]. For the analogous weak interactions of multinucleon systems, considerably less is known from experiment but these processes are equally important. The weak two-nucleon interactions currently contribute the largest uncertainty in calculations of the rate for proton-proton fusion in the Sun [11][12][13][14][15][16][17], and in neutrino-disintegration of the deuteron [18], which is a critical process needed to disentangle solar neutrino oscillations. Given the phenomenological importance of electroweak interactions in light nuclei, direct determinations from the underlying theory of strong interaction, quantum chromodynamics (QCD), are fundamental to future theoretical progress. Such determinations are also of significant phenomenological importance for calibrating long-baseline neutrino experiments and for investigations of double beta decay in nuclei. In this Letter, we take the initial steps towards meeting this challenge and present the first lattice QCD (LQCD) calculations of the np → dγ process. The results are in good agreement with experiment and show...

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Photodisintegration of deuterium and big bang nucleosynthesis

Cited by 45 publications

References 57 publications

Photodisintegration cross section measurements onW186,Re187<

Photodisintegration cross section measurements onW186,Re187<

Extracting nuclear sizes of medium to heavy nuclei from total reaction cross sections

Ab initioCalculation of thenp→dγRadiative Capture Process

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