A. A. Solnyshkin

Formation of Light Isotopes by Protons and Deuterons of 3.65 GeV/nucleon on Separated Tin Isotopes

We measure cross sections for residual nuclide formation in the mass range 7 ≤ A ≤ 96 caused by bombardment with protons and deuterons of 3.65-GeV/nucleon energy of enriched tin isotopes (112,118,120,124Sn). The experimental data are compared with calculations by the codes FLUKA, LAHET, CEM03, and LAQGSM03. Scaling behavior is observed for the whole mass region of residual nuclei, showing a possible multifragmentation mechanism for the formation of light products (7 ≤ A ≤ 30). Our analysis of the isoscaling dependence also shows a possible contribution of multifragmentation to the production of heavier nuclides, in the mass region 40 ≤ A ≤ 80.

Studies of deuteron and neutron cross-sections important for ADS research

The collaboration Energy and Transmutation of Radioactive Waste uses different setups consisting of lead, natural uranium and graphite irradiated by relativistic protons and deuterons to study transmutation of radioactive materials by produced neutrons. The activation samples are used to determine integral of proton or deuteron beams and also produced neutron flux in different places of experimental set-ups. Unfortunately almost no experimental cross-section data for deuterons with GeV energies are available. The similar situation is also for threshold (n,xn) reactions of neutrons with higher energies. Therefore we carried out series of experiments devoted to determination of deuteron reactions on copper during uranium target QUINTA irradiations by deuterons with energies from 1 GeV up to 8 GeV. The cross-sections of various threshold reactions were studied by means of different quasi-monoenergetic neutron sources with possible energies from 14 MeV up to 100 MeV. Knowledge of such cross-sections is very important for all Accelerator Driven System studies.

Experimental studies and simulations of spallation neutron production on a thick lead target

An intensive beam of 660 MeV protons from the Dubna Phasotron was directed towards a thick, lead target (not surrounded by shielding or neutron reflector) for 10 minutes. Detectors and iodine samples were placed around the target. The neutron field and the transmutation of 129I were studied by the Activation Analysis Method. MCNPX v.2.4.0 was used to simulate the experimental setup. The results of the simulations were compared to the experimental values, and the influence of the setup parts to the neutron field was explored.

Beta-decay strength measurement, total beta-decay energy determination, and dcay-scheme completeness testing by total absorption γ-ray spectroscopy

Applications of total absorption γ-ray spectroscopy and its combination with high-resolution nuclear spectroscopy methods for measurements of a β-decay strength function Sβ(E), determination of the total β-decay energy Qβ, and testing of decay-scheme completeness are presented.

Target residues formed in the 4.4 GeV deuteron-induced reaction on gold

A. R. Balabekyan, N. A. Demekhina, G. S. Karapetyan, D. R. Drnoyan, V.I.Zhemenik, J.Adam, L.Zavorka, A.A.Solnyshkin, V.M.Tsoupko-Sitnikov, J.Khushvaktov, L. Karayan, A. Deppman, V. Guimarães a) Yerevan State University A. Manoogian, 1, 025, Yerevan, Armenia b) Yerevan Physics Institute, Alikhanyan Brothers 2, Yerevan 0036, Armenia Joint Institute for Nuclear Research (JINR), Flerov Laboratory of Nuclear Reactions (LNR), Joliot-Curie 6, Dubna 141980, Moscow region Russia c) Instituto de Fisica, Universidade de São Paulo Rua do Matao, Travessa R 187, 05508-900 São Paulo, SP, Brazil d) Joint Institute for Nuclear Research (JINR), Laboratory of Nuclear Problems (LNP), Joliot-Curie 6, Dubna 141980, Moscow region Russia

Fine structure of the strength function for the β+/EC decay of the 160mHo (5.02 h) isomer

The strength function for the β+/EC decay of the deformed nucleus of the 160mHo (5.02 h) isomer is obtained from the experimental data, The fine structure of the strength function Sβ(E) is analyzed. It has a pronounced resonance structure for Gamow-Teller transitions and is found to exhibit a resonance structure for first-forbidden transitions. It is shown that for some excitation energies of the 160Dy daughter nucleus the probability of first-forbidden β+/EC transitions in the decay of the 160mHo isomer is comparable with the probability of Gamow-Teller β+/EC transitions.

Investigation of the Formation of Residual Nuclei in Reactions Induced by 660 MeV Protons Interacting with the Radioactive 237Np, 241Am and 129I Targets

241Am, 237Np and 129I radioactive targets were irradiated by proton beams with energy 0.66 GeV. The cross- sections of formation of 80, 53 and 86 residual nuclei from 241Am, 237Np and 129I are determined. The experimental results are compared with the theoretical cross-sections calculated by the cascade-evaporation model (CEM).

Fine structure of strength functions for beta decays of atomic nuclei

The β transition strength function Sβ(E) is the nuclear excitation energy distribution of moduli squared of the β-decay-type matrix elements. The function Sβ(E) determines the characteristics of β decay, the spectra of accompanying radiation, and the probabilities of delayed processes following the β decay. Until recently, tools widely used for experimental investigation of the Sβ(E) structure have been total absorption gamma spectrometers and total absorption gamma-ray spectroscopy (TAGS) which could not provide high energy resolution. Development of experimental techniques allows nuclear spectroscopy methods with high energy resolution to be used for studying the fine structure of Sβ(E). A thorough investigation of this kind has been carried out for a number of nuclei produced at the YASNAPP-2 facility in Dubna. In this review, studies involving works on measuring the fine structure of Sβ(E) in spherical and deformed nuclei are analyzed. Modern nuclear spectroscopy methods made it possible to identify the splitting of peaks from nuclear deformation in Sβ(E) for Gamow-Teller (GT) transitions. The resonance nature of Sβ(E) for first-forbidden (FF) transitions in both spherical and deformed nuclei is experimentally proven. It is shown that for some nuclear excitation energies, FF transitions can be comparable in intensity with GT transitions. Criteria for verifying the completeness of nuclear decay schemes are considered. The Sβ(E) functions obtained by TAGS and by the high-resolution spectroscopy are compared.

Recoil studies in the reaction of 12C ions with the enriched isotope 118Sn

The recoil properties of the product nuclei from the interaction of 2.2 GeV/nucleon 12C ions from Nuclotron of the Laboratory of High Energies, Joint Institute for Nuclear Research at Dubna with a 118Sn target have been studied via catcher foils method. The experimental data were analyzed using the mathematical formalism of the standard two-step vector model. The results for 12C ions are compared with those for deuterons and protons. Three different Los Alamos versions of the Quark-Gluon String Model were used for comparison with our experimental data.

Theoretical analysis of experimental data on 160Dy that were obtained in studying beta decay

Nonadiabatic effects manifesting themselves in the energies of excited states and in the probabilities for electric transitions in 160Dy are studied on the basis of a phenomenological model of the nucleus. The energies of positive-parity low-lying states and the reduced probabilities B(E2) for both intraband and interband transitions between them are calculated. A comparison with experimental data is performed.