Mesonic exchange currents and radiative thermal neutron capture by the deuteron

Abstract

Radiative capture of thermal neutrons by the deuteron: n+d→3H+γ is investigated. Wave functions built upon definite nucleon-nucleon forces are used to describe both the bound state and the scattering two-body state. The role of mesonic exchange currents and of two-nucleon forces are investigated in detail. Finally, the bearing of genuine three-nucleon forces on the cross sections and other related properties is exhibited

Measurement of astrophysical S factors and electron screening potentials for d(d, n)3He reaction In ZrD2, TiD2, D2O, and CD2 targets in the ultralow energy region using plasma accelerators

“…Study of the ES effect for the dd reaction has been carried out in a more detailed way and with wide variety of target materials compared with that for d 3 He and d 6 Li reactions. It is due to the fact that the yields of the d(d, p)t and d(d, n) 3 He reactions in the ultralow deuteron collision energy region (2-10 keV) substantially exceed respective yields in the d 3 He and d 6 Li reactions. This circumstance gives the opportunity not only to determine values of astrophysical S factors and ES potentials with high confidence level for both dd reaction channels but also to carry out the correct comparison of these values with the results of theoretical calculations.…”

“…For clarification of the nature of such a divergence between the results of various studies (see the table) we have performed the experimental study of d(d, n) 3 He reaction in the ultralow deuteron energies region (4-15 keV) using TiD 2 and ZrD 2 targets at the temperature 293 K. The results of these experiments are presented below in Section 4.3. Besides it, to obtain a quantative information on ES potential of n 3 He channel in dd reaction occurring in dielectrics (deuterated polyethylene CD 2 and frozen heavy water D 2 O) we performed reanalysis of previous experiments carried out with targets of these materials [32][33][34][35][36].…”

“…20 ZrD 2 297 ± 8 [19] 112 [19] 20 ZrD 2 319 ± 3 [25] TiD -88 TiD 3.76 66 ± 15 [18] 20 TiD 1. 3 30 [20] 100 [19] 50 TiD 1.1 50 [21] 100 TiD 0.26 250 ± 40 [21] 150 TiD 0.23 295 ± 40 [21] It is assumed in the modern star models that at high level of the star matter density reached in the process of the star evolution the rate of nuclear reactions increases, due to the screening of positively charged nuclei by negatively charged electrons. Electron screening (ES) results in the effective decrease of Coulomb barrier and thus in the increase of the nuclear reaction rate [9][10][11].…”

“…is of a great interest due to possibility of: verification of fundamental symmetries in strong interaction (charge and isotopic invariance of nuclear forces) [1,2]; acquisition of information on contribution and structure of exchange meson currents [3,4], which contribution into interaction in the ultralow energy region becomes significant (e.g., in case of radiative capture of protons by deuterons and tritons: p + d → 3 He + γ; p + t → 4 He + γ); acquisition of information for microscopic description of nucleon-nucleon interaction; testing of theoretical articles, dedicated to three-body tasks solution based on modern representation of nucleon-nucleon interaction potential within the bounds of realistic two-body, two-body plus three-body forces [5]. Concerning astrophysics, there is a need for the reliable experimental information on parameters of all general processes, included in hydrogen and carbon cycles, that occur in the stars with ultralow energy of nuclear interaction [6][7][8].…”

with effective field theory

“…Later, Phillips [16] emphasized the importance of initial state interactions and two-body currents to capture reaction in the three-body model calculation, by considering a central, separable interaction. In recent years, a series of calculations of increasing sophistication with regard to the description of both the initial and final state wave functions and two-body current model were carried out [17]. These efforts culminated in the 1990 Friar et al [18] calculation of the nd → 3 Hγ total cross section, quartet capture fraction, and photon polarization, based on converged bound and continuum state Faddeev wave functions, corresponding to a variety of realistic Hamiltonian models with two-and three-nucleon interactions, and a nuclear electromagnetic current operator, including the long-range two-body components associated with pion exchange and the virtual excitation of intermediate ∆ resonances.…”