Nuclear Data for Astrophysics
Measurement and Evaluation of Nuclear Data Required for Astrophysical Applications
Tech Area / Field
- PHY-ANU/Atomic and Nuclear Physics/Physics
8 Project completed
Senior Project Manager
Lapidus O V
National Nuclear Center of the Republic of Kazakstan / Institute of Nuclear Physics, Kazakstan, Almaty
- VNIIEF, Russia, N. Novgorod reg., Sarov
- University of Colorado at Boulder, USA, CO, Boulder\nTexas A&M University, USA, TX, College Station
Project summaryThe aim of the present Project is the measurement and evaluation of the cross sections of reactions with charged particles in the energy range of Elab = 0.2-10 MeV which are important for the astrophysical applications and obtaining of their reaction rates using the numerical techniques. The list of reactions chosen for the research is motivated, first of all, by the requirements on the nuclear data formulated in a perfect review /1/, and also by our methodical and technical opportunities.
The basis for this work is the library of the evaluated nuclear data (SaBa), which includes more than 100 reactions, induced by charged particles on light nuclei up to Boron. This library has been created in the framework of the project of International Scientific and Technical Center (ISTC №145-95 "Development of the library of evaluated nuclear data of charged particles for International Thermonuclear Reactor (ITER) and other fusion applications"). It contains not only the recommended nuclear data files and the corresponding experimental data, but also the programs of operating with them including the programs of statistical processing for obtaining of approximating spline–curves.
It is proposed during the performing of the project to continue works for modernization and further extension of created before library of the evaluated nuclear data according to the astrophysical tasks. At present the low energy limit of existing experimental data does not reach the energy ranges relevant for the processes in stars. Evaluated data from the mentioned above library are also limited by available experimental cross sections. This ‘void’ of data presented in the library may be filled by the theoretically justified extrapolation of the recommended cross sections to the zero energy range. With this purpose on the basis of numerical techniques developed by Russian and Kazakh theorists /2-7 / the calculations of the cross sections for interaction of charged particles with light nuclei will be carried out at super-low energies for a number of reactions presented in SaBa library.
Apart from the work on the extrapolation of recommended cross sections from the library SaBa to the super-low energies, it is proposed to continue the compilation (First set of library of experimental data in EXFOR format, executed within the project ISTC №145-95, has been commissioned already into the international nuclear data network) and to conduct the cross sections measurements of some nuclear reactions, which are important for astrophysics.
The unique electrostatic recharging accelerator complex RAC-2-1, which is available in DSE “INP” NNC RK, producing the crossed beams with energy resolution of 150 eV in a range 0.2-1.5 МeV for protons and also tandem of the accelerators with the energies up to 12 МeV in RFNC-VNIIEF allow to carry out the precise experiments for the measurements of nuclear constants in wide energy range. That, in its turn, may provide the success of theoretical extrapolations of obtained experimental data into the low energies region. The scientists of DSE “INP” NNC RK and RFNC-VNIIEF have accumulated a wide experience in the measurements and evaluation of the reaction cross sections, which present interest for the astrophysical applications. In particular, the works of scientists from RFNC-VNIIEF on the cross sections measurements of such reactions as 3H(t,2n)4He, 6,7Li(d,t)5,6Li /8,9/, which are important for the calculations of the processes in hot plasma, as well as the works of scientists from INP NNC RK /10,11/ are well known.
According to C.Barns /7/ the reactions induced by interaction of carbon with oxygen can be effectively occurred at star temperatures T~(1.3-3.5)T9 (where T9=109K). It results in formation of fast ?-particles and protons, and also in formation of the 20Ne, 23Na, 23Mg, 28Si, 30,31P, 30,31S nuclei. The produced in these reactions fast ?-particles, protons and neutrons may interact with the nuclei synthesized at this moment in stars due to the hydrogen, helium and CNO-cycles. As a result there is a production of such nuclei as 20,21,22Ne, 23Na, 24,25,26Mg, 26,27Al, 28,29,30Si, 30,31P. However, the main products are still the 20Ne and 24Mg nuclei. The last one is generated mainly due to the reaction of the radiation capture of ?-particles or protons by the 20Ne or 23Na nuclei, respectively.
For example, the low energy limit of the measured cross sections for the 12С+12С system is the value Е~2,5 МeV(center of mass system). Whereas at the energies more than 4 МeV various measurements are in good agreement, at lower energies values of the existing data are rather inconsistent /13/. It results in large errors in extrapolation procedure for the energies corresponding to the carbon burning temperatures in stars. Therefore, the task of the present project consists not only in realization of the measurements at the minimum possible energies, but also in more precise estimations of already existing data in the range of E ~2,5-4 МeV.
Basing on the conclusions from /1/ concerning the status of the experimental data that are necessary for the calculations of the hydrogen, helium and CNO-cycles it is suggested in course of the present project to measure the following reactions in addition to listed above:
12,13C(p,?)13,14N; 14N(p,?)15O and 16O(p,?)17F (CNO-cycle), as well as the 7Li(d,p)8Li and 7Li(p,?)4He reactions. The precise value of the 7Li(d,p)8Li cross section is required for the monitoring of 7Be(p,?)8B reaction. The 7Li (p,?)4He reaction is a key one in a cycle of hydrogen burning. This reaction was investigated experimentally but as estimations showed /14/, there are discrepancies in available experimental data, so there is strong interest in additional experimental measurements.
Thus the objectives of this project are as follows:
Measurements of the interaction cross sections of carbon ions with carbon and of oxygen with oxygen in the energy range 2,5 –4 MeV which result in formation of fast protons, -particles and the 23Na, 24,25,26Mg, 26,27Al, 30,31P, 28,29,30Si nuclei, receiving of experimental data for (p,), (p,) and (d,p) reactions on 12,13C, 14N,16.17O, 7Li nuclei at the minimal incident energy (0,2 MeV and higher).
Choice and development of theoretical approaches for calculation of interaction potentials of particles with nuclei for indicated reactions, calculation of wave functions, spectroscopic characteristics and cross sections within different model for (p,), (n,), (p,) and (d,p) reactions on 7Li, 7Ве, 12,13C, 14N,16.17O, and finally, calculation and extrapolation of S- factors for reactions studied to the zero energy region.
Creation of the Web site with the date base on cross sections values for interaction of charged particles with light nuclei at the low and super-low energies.
References:/1/ G. Wallerstein et. аl. Synthesis of elements in stars: forty years of progress. //Rev. of Mod. Phys. V.69, №4, 1997, p.995-1084.
/2/ S.Dubovichenko, A.Dzhazairov-Kakhramanov. Photonuclear processes for 7Li and 7Be nuclei on the base of cluster model for potentials with forbidden states. // Yad.Fiz., 1995, v. 58, №4, p.635-641
/3/ N.A. Burkova, M.A. Zhusupov. Two-cluster disintegration of 6Li and 7Li by linearly polarized photons. // Nucl. Phys. A586, 1995, p.293-315.
/4/ L. Lasarev. Theory of the threshold phenomena in nuclear spectroscopy //Materials XI of the International seminar on exact measurements in nuclear spectroscopy. // VANT, ser. fiz. Physics Nucl. Reactors, TIAS XI, spec.issue p. 24-28.
/5/S.Abramovich, B.Guzhovskij, L.Lasarev. Threshold phenomena in nuclear reactions// Phys.of Element.Part. and Atomic Nucl., 1992, v.23. p. 305-363.
/6/ V.I.Kukulin, V.Pomerantzev, S.V.Zuev. Fast convergent method for reconstruction of complex interaction potentials from scattering phase shifts and cross sections.// Yad.Fiz., 1996, v. 59, №3, p.428.
/7/S.G.Cooper, R.S.Mackintosh and V.I.Kukulin. Determination of 6Li-4He interaction from multi-energy scattering data. // Nucl. Phys. A, 1998. v.645. p.399-409.
/8/ V.Serov, S.Abramovich, L.Morkin. Total cross-section measurement for T(T,2n)4He reaction at low energies. // Izv. AN USSR, Ser.Fiz. 1971. v.35, v.165. Engl. issued SJA. 1977. v.42. v.66.
/9/S.Abramovich, L.Generalov, A.Zvenigorodskii. Measurement of cross-sections for 6,7Li(d,t) reactions with radiochemical methods.// Intern. Conf. on Nucl. Data for Science and Technology,1997,Trieste, p.632-634, ed.G.Reffo, A.Ventura, C.Grandi.
/10/ N.Burtebaev, A. Duisebaev, G. Ivanov, S.B. Sakuta. Elastic and inelastic scattering of 50 MeV energy -particles by 6Li and 7Li nuclei: the role of exchange effects in anomalous scattering at large angles. // Yad.Fiz.,1996, v.59, p. 33-42.
/11/ N.Burtebaev, A. Duisebaev, G. Ivanov, S.B. Sakuta. Effects of triton-clusters exchange in 3He inelastic scattering on 6Li nuclei. // Yad.Fiz., 1995. v.58, №4. p. 596-603.
/12/ S.A.Barns. Nuclear reactions in strongly evolved stars. // In issue: Nuclear astrophysics, M., "World", 1986, p. 191-227.
/13/ H.W.Becker, K.U.Kettner, C.Rolfs and H.P.Trautvetter. The 12C + 12C Reaction at Subcoulomb Energies (II)// Z.Phys. A -Atoms and Nuclei 300, 1981, p.305-312.
/14/ S. Abramovich, B.Guzhovskij, V.Zherebtzov, A.Zvenigorodskij. Nuclear Physics Constants for Thermonuclear Fusion. // A Reference Handbook. IAEA Report, INDC(CCP)-326/L+F.
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