Radiative n 11 B capture accounting 21 and 430 keV resonances

2017

Int. J. Mod. Phys. E

Abstract:We have studied the neutron-capture reactions 8 Li(n,) 9 Li and its role in the primordial nucleosynthesis. The n+ 8 Li 9 Li+ reaction has a significant astrophysical interest, because it includes into one of the variants of chain of primordial nucleosynthesis processes of the Universe and thermonuclear reactions in type II supernovae. Furthermore, we consider the 9 Be(p,) 10 B reaction in the astrophysical energy range in the modified potential cluster model with splitting of orbital states according to Young tableaux and, in some cases, with forbidden states. The reaction 9 Be(p,) 10 B plays an important role in primordial and stellar nucleosynthesis of light elements in the p shell. Hydrogen burning in secondgeneration stars occurs via the proton-proton (pp) chain and CNO cycle, with the 9 Be(p,) 10 B reaction serving as an intermediate link between these cycles. Furthermore, the possibility of describing available experimental data for the total reaction cross sections of neutron radiative capture on 10 Be at thermal and astrophysical energies has been shown. This reaction is a part of one of the variants of the chain of primordial nucleosynthesis of the Universe due to which the elements with a mass of A > 11-12 may be formed. The results in the field of study of thermonuclear proton capture reaction on 10 B at ultralow, i.e., astrophysical energies will be presented further. The possibility of description of the experimental data for the astrophysical S-factor of the proton radiative capture on 16 O to the ground state of Keywords: Nuclear astrophysics; primordial nucleosynthesis; light atomic nuclei; low and astrophysical energies; radiative capture; total cross section; thermonuclear processes; potential cluster model; forbidden states. 21.60.Gx, 25.20.Lj, 25.40.Lw, 26.20.Np, 26.35.+c, 26.50.+x, 26.90.+n PACS Number(s): IntroductionThis review is the logical continuation of our works devoted to the radiative proton and neutron capture on light nuclei that were published in Int. J. Mod. Phys. E 21, 1250039 (2012); 22, 1350028 (2013); 22, 1350075 (2013); 23, 1430012 (2014). Astrophysical aspects of the reviewAs we know, light radioactive nuclei play an important role in many astrophysical environments. In addition, such parameter as cross section of the capture reactions as 2 a function of energy and reaction rates are very important for investigation of many astrophysical problems such as primordial nucleosynthesis of the Universe, main trends of stellar evolution, novae and super-novae explosions, X-ray bursts etc. The continued interest in the study of processes of radiative neutron capture on light nuclei at thermal (> 10 meV) and astrophysical (> 1 keV) energies is caused by several reasons. Firstly, this process plays a significant part in the study of many fundamental properties of nuclear reactions, and secondly, the data on the capture cross sections are widely used in a various applications of nuclear physics and nuclear astrophysics, for example, in the process of studying of...

Section: The N 10 Be Interaction Potentialsmentioning

confidence: 99%

Study of the nucleon radiative captures 8Li(n,γ)9Li, 9Be(p,γ)10B, 10Be(n,γ)11Be, 10B(p,γ)11C, and 16O(p,γ)17F at thermal and astrophysical energies

2017

Int. J. Mod. Phys. E

“…Necessity of study processes neutron radiative capture on boron isotopes 10,11 B(n,γ) lies at the interface of interests either fundamental, scientific (primordial nucleosynthesis of the Universe) [1][2][3][4][5] or practical, applied (exploitation of nuclear reactors) [6]. The reliable information on such reaction rates depending on temperature in the wide range required for further development of these directions.…”

Section: Introductionmentioning

confidence: 99%

“…The same circle of questions, although in somewhat other area, is a point at issue of the role of chain 10 B(n,) 11 B(n,) 12 B(n,) 13 B(n,) 14 B(n,) 15 B( -) 15 C reactions with the efficiency to the carbocycle in stars (including evolution of supernovae at the stage of pre-bang etc.) [7][8][9][10]. According to modern independent assessments the disagreements of estimations of rates for considered reactions is equal to 100% [2].…”

Section: Introductionmentioning

confidence: 99%

Influence of low-lying resonances on reaction rates for 10B(n,γ)11B capture

Burkova

2019

Nuclear Physics A

The possibility of description available experimental data for total cross section for reaction of the neutron capture on 10 B at energies from 25.3 meV to 1.0 MeV was considered in the frame of the modified potential cluster model with forbidden states, classification of the orbital cluster states according to Young diagrams and taking into account the resonance behavior of phase shifts of the n 10 B elastic scattering. The obtained results agree with the experimental measurements. The calculated total cross sections are used for obtaining the reaction rate of the neutron capture on 10 B at the temperature range from 0.01 to 10T 9 . The reaction rate rises essentially at temperatures above 0.3-0.4 T 9 , conditioned by the resonances at the energy above 100 keV.1. The first RS of 11 B at the excitation energy of 11.600(20) MeV or 146(20) keV relatively to the threshold of the n 10 B channel has J  = 5/2 + at the total width of 180(20) keV and neutron width of 4 keV [16,18]. It can be matched to the 6 S 5/2 scattering wave with FS or mixed by spin 6+8 D 5/2 scattering wave also with the bound FS.2. The second RS has the excitation energy of 11.893(13) MeV or 439(13) keV relatively to the threshold of the channel. Its total width of 194(6) keV, neutron width of 31 keV [18] and moment J  = 5/2 -. Therefore, it can be matched to the mixtured 6+8 P 5/2 scattering waves without FSs.3. The third RS has the excitation energy of 12.040(130) MeV or 586(13) keV relatively to the threshold. Its total width is about of 1000 keV [16,18], neutron width changing from 770 keV [18] to 1.34 MeV [16], and moment is equal to J  = 7/2 + -it can be matched to the 8 S 7/2 wave or 6+8 D 7/2 scattering waves with FS.4. The next resonance is located at the energy above 1 MeV, its moment does not fix unambiguously (see Table 11.18 in work [16]), and we do not consider it, because it is impossible to define its accessory to the certain partial wave.The resonance levels that can be matched to the P 3/2 or P 7/2 , P 9/2 states [16] are absence at the energy below 1 MeV in spectrum of 11 B. Therefore, their phase shifts can be equalized to zero, and because there are no FSs in these waves, so the depth of potentials can be equalized to zero too [13,14]. Consequently, we will consider E1 transitions the GS and four (2 nd , 3 rd , 4 th and 9 th ) ES in P waves from S and D scattering states and M1 process from the resonance 6 P 5/2 scattering wave. Methods of calculation of total cross sections

“…Below we use our expertise and a lot of experience in using the single-channel modified potential cluster model (MPCM) with forbidden states (FS) and the classification of cluster states according to Young diagrams (Dubovichenko 2015a(Dubovichenko , 2016Dubovichenko & Dzhazairov-Kakhramanov 2012, 2015, 2016, 2017Dubovichenko, Dzhazairov-Kakhramanov & Afanasyeva 2017;Dubovichenko & Burkova 2014;, and apply to study the radiative 3 He( 2 H,γ) 5 Li capture. This model is much simpler than the known Resonating Group Method (RGM) (Mertelmeir & Hofmann 1986) and its modifications (Descouvemont et al 2013(Descouvemont et al , 2014, but in many cases it allows one to obtain quite reliable numerical results for many reactions such as radiative capture.…”

Section: Some Theoretical Resultsmentioning

confidence: 99%

“…The modified potential cluster model, which is used in the present calculations, is described in detail in (Dubovichenko 2015a(Dubovichenko , 2016 and, in part, in (Dubovichenko & Dzhazairov-Kakhramanov 2012, 2015, 2016, 2017Dubovichenko, Dzhazairov-Kakhramanov & Afanasyeva 2017;Dubovichenko & Burkova 2014;. One of its modifications relies on the explicit dependence of the interaction potentials on Young orbital diagrams and on taking into account the mixing of cluster states according to these diagrams.…”

Section: Model and Some Theoretical Methodsmentioning

confidence: 99%

Radiative 3He(2H,γ)5Li Capture at Astrophysical Energy and Its Possible Role in Accumulation of 6Li at the BBN

Burkova

Recent Progress in Few-Body Physics

et al. 2020

Self Cite

Big Bang Nucleosynthesis (BBN) relevance reactions 3 He( 2 H,γ) 5 Li, 3 H( 3 He,γ) 6 Li, 5 Li(n,γ) 6 Li as a key to approach for scenario of 6 Li formation are treated. The rates of reaction for these processes are analyzed. Comparison of the reactions rates and the prevalence of light elements leads to the assumption that the two-step process 2 H + 3 He  5 Li +  and n + 5 Li  6 Li +  can make a significant contribution to the formation of 6 Li at the BBN at least at temperatures T 9 of the order of unity.Calculations of the total cross sections, astrophysical S-factor, and reaction rates have been performed for 3 He( 2 H,γ) 5 Li radiative capture within the modified potential cluster model with forbidden states, which follow from the classification of the orbital cluster states according to Young diagrams. Numerical data and corresponding parametrizations cover the energy range up to 5 MeV and temperature range T 9 <10. An updated compilation of detailed data for the reaction 3 He( 2 H,γ) 5 Li are presented.Let us now examine in more detail the various aspects of the 3 He( 2 H, γ) 5 Li reaction, including the experimental data presented in the data base (EXFOR, 2013) and the original references cited therein, and the role of this process in various fields of application. Nuclear astrophysics aspectsOur parametrization of the experimental data for 2 H capture in 3 He (Buss et al. 1968) for the Sfactor at energies from 0.2 to 1.0 MeV according to Breit-Wigner and its further extrapolation 8 ) , ( J J I J J NJ P K NJ A J J J J J J J J