Saint-petersburg state university russian academy of sciences joint institute for nuclear research
PARTICLE MATTER DENSITY: APPLICATION TO THE
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- GAMOW-TELLER RESONANCES IN THE COMPOUND- NUCLEUS 118 Sb: PUZZLES OF THE SAROV’S EXPERIMENT
- SUPERHEAVY NUCLEI SYNTHESIS IN HIGH INTENSIVE PULSED NEUTRON FLUXES
- NRV WEB KNOWLEDGE BASE ON LOW ENERGY NUCLEAR PHYSICS
- EXPERIMENTAL INVESTIGATIONS OF ATOMIC NUCLEUS PROPERTIES SEARCH FOR NUCLEAR STABLE MULTINEUTRONS IN THE TERNARY FISSION OF 232
- ISOBAR ANALOGUE STATES (IAS), DOUBLE ISOBAR ANALOGUE STATES (DIAS), CONFIGURATION STATES (CS), AND DOUBLE CONFIGURATION STATES (DCS)
- SEARCH FOR CLUSTER ROTATIONAL BANDS IN 11 B
- SEARCH FOR STATES WITH ABNORMAL RADII IN 13 C
PARTICLE MATTER DENSITY: APPLICATION TO THE
MEASURED CHARGE DENSITY DIFFERENCE BETWEEN THE ISOTONES 206 Pb – 205 Tl Shlomo S. 1,2 , Anders M.R. 1 , Talmi I. 2 1 Cyclotron Institute, Texas A&M University, College Station, Texas, USA; 2 The Weizmann Institute of Science, Rehovot, Israel E-mail: s-shlomo@tamu.edu We present a novel method, using the single particle Schrodinger equation, to determine the central potential directly from the single particle matter density and its first and second derivatives. As an example, we consider the experimental data for the charge density difference between the isotones 206 Pb – 205 Tl, deduced by analysis of elastic electron scattering measurements and corresponds to the shell model 3s 1/2 proton orbit, and determine the corresponding single particle potential (mean-field). We also present results of least-square fits to parametrized single particle potentials. The 3s 1/2 wave functions of the determined potentials reproduce fairly well the experimental data within the quoted errors. The fair agreement with fitted potentials may be an indication that effects of short range correlations on charge distributions due to shell model wave functions are not significant. More accurate experimental data, with uncertainty smaller by a factor of two or more, may answer the question how well can the data be reproduced by a calculated 3s 1/2 wave function. 60 GAMOW-TELLER RESONANCES IN THE COMPOUND- NUCLEUS 118 Sb: PUZZLES OF THE SAROV’S EXPERIMENT Urin M.H. National Research Nuclear University “MEPhI”, Moscow, Russia E-mail: urin@theor.mephi.ru More than 30 years ago, two rather narrow (Γ ≈ 1 MeV) resonance structures have been observed in the excitation function of the 117 Sn (pn tot )-reaction [1]. The use of the methods successfully exploited early by the Guzhovskii’s group (Sarov) in experimental studies of IAR allowed this group to deduce with a high accuracy the parameters of the mentioned structures associated by the authors with the Gamow-Teller resonances (GTRs) in the compound-nucleus 118 Sb. Up to now these unique experimental results are not reasonably explained. This point, and intention to essentially extend experimental studies of excitations functions of the (pp')- and (pn tot )-reactions with a number of tin target-nuclei [2] stimulate us to come again to experimental and theoretical studies of the GTR in antimony isotopes. We plan to discuss: (i) a comparison of the results of Ref. [1] with the corresponding data obtained by means of the direct ( 3 He,t)-reaction [3]; (ii) attempts to understand the mentioned experimental results from the theoretical point of view with inclusion into consideration of the specific structure effect – the GTR splitting in antimony isotopes near A = 118 [4,5]. A number of open questions and possible theoretical studies are planned to be discussed. The main puzzle is the noticeable difference the GTR total width deduced from the direct and resonance reactions. The small GTR total width might be a signature of an approximate spin-isospin SU(4)-symmetry conservation in nuclei. This work is partially supported by RFBR (grant No. 15-02-08007a). 1. B.Ya.Guzhovskii, B.M.Dzyuba, V.N.Protopopov // JETP Lett. 1984. V.40.P.283. 2. S.N.Abramovich, A.G.Zvenigorodskii // Nucl. Phys. Eng. 2013. V.4. P.1097. 3. K.Pham et al. // Phys. Rev. C. 1995. V.51. P.526. 4. V.G.Guba, M.A. Nikolaev, M.G.Urin // Phys. Lett. B. 1989. V.218. P.283. 5. S.Yu.Igashov, V.A.Rodin, M.H.Urin // Phys. At. Nucl. 2013. V.76. P.429. 61 SUPERHEAVY NUCLEI SYNTHESIS IN HIGH INTENSIVE PULSED NEUTRON FLUXES Lutostansky Yu.S. 1 , Lyashuk V.I. 1,2 , Panov I.V. 1,3 1 National Research Center “Kurchatov Institute”, Moscow, Russia; 2 Institute for Nuclear Research, Russian Academy of Science, Moscow, Russia; 3 Institute for Theoretical and Experimental Physics, Moscow, Russia E-mail: lutostansky@yandex.ru Synthesis of heavy and superheavy (SH) nuclei in intensive pulsed neutron fluxes described using adiabatic model [1, 2] based on the astrophysical theory of r-process nucleosynthesis [3]. The nature of neutron pulses may be astrophysical and artificial one. So the pulse duration time may vary from microseconds (nuclear/thermonuclear explosion) to some seconds (star explosion). In the middle of this interval are pulsed reactors with milliseconds impulses duration time. For calculating heavy and SH nuclei yields we must know the parameters of neutron fluxes, their dependence in time and properties of short lived nuclei involved in this process. In the very shot-prompt process of thermonuclear explosion to produce SH nuclei the initial isotope composition should include transuranium elements [4]. The calculations were performed and for the super extreme neutron fluxes much higher than in “Hutch” test [5]. In nuclear pulsed reactors the duration time of neutron impulse may differ strongly that is principally influence on the heavy nuclei yields. We have considered nucleosynthesis for conditions reached in pulsed reactors. New data predictions for heavy nuclei from self-consistent microscopic approach [6] were used. When duration of neutron exposition t >> 10 –6 s in explosive processes and free number density is higher than in artificial explosions, the answer to the question ”whether SHE can be formed?” [7] strongly depends on predictions of the beta-delayed and spontaneous fission rates, mass and fission barriers values. All these questions are analyzed in this work and different problems of heavy and superheavy nuclei production in intensive neutron fluxes of explosive processes are discussed. The work is partly supported by the Russian Foundation for Basic Research grants no. 13-02-12106 ofi-m, 14-22-03040 ofi_m and SNF SCOPES project № IZ73Z0_152485. 1. Yu.S.Lutostansky et al. // Bull. Russ. Acad. Sci. Phys. 2011. V.75. P.533. 2. V.I.Lyashuk // Bull. Russ. Acad. Sci. Phys. 2012. V.76. P.1182. 3. B.M.Burbridge et al. // Rev. Mod. Phys. 1957. V.29. P.547. 4. Yu.S.Lutostansky, V.I.Lyashuk // Proc. Int. Seminar ISINN-21. JINR Dubna 2014. P.147. 5. R.Hoff // Preprint UCRL-81566. Lawrence Livermore Laboratory. USA. 1978. 6. S.V.Tolokonnikov et al. arXiv: 1406.7095v3. 7. I.Petermann et al. // Eur. Phys. J. 2012. V.48. P.122. 62 NRV WEB KNOWLEDGE BASE ON LOW ENERGY NUCLEAR PHYSICS Karpov A.V. 1 , Denikin A.S. 1,2 , Alekseev A.P. 3 , Samarin V.V. 1 , Naumenko M.A. 1 , Rachkov V.A. 1 1 Flerov Laboratory of Nuclear Reactions, JINR, Dubna, Russia; 2 International University “Dubna”, Dubna, Russia; 3 Chuvash State University, Cheboksary, Russia E-mail: karpov@jinr.ru The NRV web knowledge base on low-energy nuclear physics [1] was developed at FLNR, JINR to allow quick access to the up-to-date experimental data on nuclear structure and cross sections of nuclear reactions as well as analysis of the data and modeling of the processes of nuclear dynamics within well-established physical approaches. There are several unique advantages of the NRV web knowledge base compared to other nuclear databases. As a rule, the nuclear databases supply users with ordinary text information. Thus, to obtain even the simplest systematics the user must manually prepare a separate file with all the necessary data and then use a separate graphical package to plot it. The NRV web knowledge base contains special programs for graphic representation of the data, their comparative analysis and obtaining systematics of all kinds either over a group of nuclei or the whole nuclear map. Our databases on experimental cross sections of nuclear reactions allow quick processing, easy graphical comparison and analysis of the data within different theoretical models. All this is performed just in a window of the web browser without downloading and installation of any additional computational or graphical software. The computational programs for modeling low-energy nuclear dynamics are the significant part of the NRV web knowledge base. Other advantages include simplicity of use, the interactive graphical interface allowing to adjust the parameters of theoretical models, detailed descriptions, graphical representation of the results, easy access via the Internet, etc. The NRV web knowledge base contains most of the available experimental data on properties of nuclei as well as data on the cross sections of different nuclear reactions including fusion, evaporation and elastic scattering. The available codes include the nuclear map, the shell model, the optical model, the CC model, the DWBA approach, reaction kinematics, etc. The NRV web knowledge base is now widely used not only for scientific purposes, but also as a valuable tool in the education process in the field of nuclear physics [2]. This work was supported by grant 15-07-07673-a of the Russian Foundation for Basic Research (RFBR). 1. NRV web knowledge base on low-energy nuclear physics. http://nrv.jinr.ru/ 2. A.S.Denikin et al. // Proc. of Conf. “Scientific services in Internet”. 2008. P.393. 63 EXPERIMENTAL INVESTIGATIONS OF ATOMIC NUCLEUS PROPERTIES SEARCH FOR NUCLEAR STABLE MULTINEUTRONS IN THE TERNARY FISSION OF 232 Th INDUCED BY ACCELARATED α-PARTICLES Novatsky B.G., Nikolskii E.Yu., Sakuta S.B., Stepanov D.N. National Research Centre “Kurchatov Institute”, Moscow, Russia E-mail: sbsakuta@mail.ru One way of searching for stable neutron nuclei is the induced fission of actinide isotopes. Previously, we reported the results of our measurements where possible emission of multineutrons from the fission 238 U was observed by characteristic 1384 keV γ-rays from the 88 Sr( x n,(x–4)n) 92 Sr→ 92 Y process in the activated strontium sample [1]. Recently, we started new series of experiments to search for light multineutrons among of products of the 232 Th ternary fission induced by α-particles accelerated on the NRC cyclotron up the energies of 50 and 62 MeV. The identification of neutron nuclei was done by the activation method by measuring of γ-rays from β-radioactive nuclei 28 Mg produced in the transfer reactions: 27 Al( x n,(x–2)np) 28 Mg, 27 Al( x n,(x–3)nd) 28 Mg and 27 Al( x n,(x–4)nt) 28 Mg. The choice of 28 Mg was defined by the fact that the very intensive γ-rays 1342 keV (52.6%) and 1778 keV (100%) are emitted by the radioactive nuclei from the chain 28 Mg→ 28 Al→ 28 Si and half-life of 28 Mg is acceptable for the offline measurements (T 1/2 =20.91 h). The irradiation time was about 8 h at the beam current of 2 μA. Gamma spectra were measured after cleaning of the irradiated samples from 24 Na isotope which was produced in the 27 Al(n,α) background reaction. The cleaning was done by the method of thermal diffusion in an electrostatic field. Analysis of the experimental data with the 232 Th target is in progress. This measurement could confirm the results of our early work [1]. 1. B.G.Novatsky, E.Yu.Nikolskii, S.B.Sakuta, D.N.Stepanov // JETP Letters 2012. V.96. P.280. 64 ISOBAR ANALOGUE STATES (IAS), DOUBLE ISOBAR ANALOGUE STATES (DIAS), CONFIGURATION STATES (CS), AND DOUBLE CONFIGURATION STATES (DCS) IN HALO NUCLEI. HALO ISOMERS Izosimov I.N. Joint Institute for Nuclear Research, Dubna, Russia E-mail: izosimov@jinr.ru The IAS of the halo nuclei may also have a halolike structure [1]. In [2] it is shown that the IAS of the 6 He ground state (two-neutron halo nucleus), i.e., the 3.56 MeV 0 + state of 6 Li, has a neutron-proton halo structure. In the general case [3] the IAS is the coherent superposition of the excitations like neutron hole– proton particle coupled to form the momentum J=0 + . The IAS has the isospin T=T z +1=(N−Z)/2+1, where T z =(N−Z)/2 is the isospin projection. The isospin of the ground state is T=T z =(N−Z)/2. When the IAS energy corresponds to the continuum, the IAS can be observed as a resonance. CS are not the coherent superposition of such excitations and have T=T z =(N−Z)/2. One of the best studied configuration states is the antianalog state (AIAS) [4]. The DIAS has the isospin T=T z +2 and is formed as the coherent superposition of the excitations like two neutron holes–two proton particles coupled to form the momentum J=0 + . For the IAS, CS, DIAS, and DCS the proton particles have the same spin and spatial characteristics as the corresponding neutron holes. When the parent state is a two-neutron halo nucleus, IASs and CSs will have the proton-neutron halo structure, DIASs and DCSs will have the proton-proton halo structure. For nuclei with enough neutrons excess IASs and CSs can have not only the pn halo component but also the nn halo component, DIASs and DCSs can have both pp, nn, and pn components [4]. Such excited states and resonances as IAS, DIAS, CS, and DCS in halo nuclei can also have a halolike structure of different types (nn, pp, pn). IAS, DIAS, CS, and DCS can simultaneously have nn, np, and pp halo components in their wave functions [4]. When the halo structure of the excited and ground states are different than the isomers are able to be formed. From this point of view some CS and DCS depending on theirs halo structure, may be observed as isomers (halo isomers). Structure of the excited states with different isospin quantum numbers in halolike nuclei is discussed. Special attention is given to the nuclei for which ground state does not have a halo structure but excited states may have a halo structure. B(Mλ) and B(Eλ) values for γ-transitions in 6,7,8 Li, 8,9,10 Be, 8,10,11 B, 10,11,12,13,14 C, 13, 14,15,16,17 N, 15,16,17,19 O, and 17 F are analyzed. 1. Y.Suzuki, K.Yabana // Phys. Lett. B. 1991. V.272. P.173. 2. L.Zhihong et al. // Phys. Lett. B. 2002. V. 527. P.50. 3. Yu.V.Naumov, O.E.Kraft. Isospin in Nuclear Physics. 1972. Nauka. Moscow. 4. I.N.Izosimov // Proc. Int. Conf. EXON2012. World Scientific. 2013. P.129. 65 SEARCH FOR CLUSTER ROTATIONAL BANDS IN 11 B Danilov A.N. 1 , Demyanova A.S. 1 , Ogloblin A.A. 1 , Belyaeva T.L. 2 , Goncharov S.A. 3 , Trzaska W. 4 1 Russian Research Center “Kurchatov Institute”, Moscow, Russia; 2 Universidad Autonoma del Estado de Mexico, Toluca, Mexico; 3 Lomonosov Moscow State University,Moscow, Russia; 4 The Accelerator Laboratory of the Department of Physics of the University of Jyväskylä, Jyvaskula, Finland E-mail: danilov1987@mail.ru New experimental data on differential cross-sections of the 11 В + α inelastic scattering at Е(α) = 65 MeV leading to the most of the known 11 В states at the excitation energies up to 14 MeV was obtained [1]. The data analysis was done by two methods: DWBA and Modified Diffraction Model [2], which allows determining the radii of the excited states. The radii of the low-lying excited states (excitation energy less than ~ 7 MeV) practically coincide with the radius of the ground state. This result is consistent with the traditional view of the shell structure of the low-lying states in 11 B. Most of the observed high-energy excited states (excitation energy more than ~ 7 MeV) are distributed among four rotational bands: К = 3/2 – : 8.56 (3/2 – ) – 10.34 (5/2 – ) – 11.60 – 13.14 (9/2 – ) MeV, К = 1/2 + : 6.79 (1/2 + ) – 9.88 (3/2 + ) – 11.60 (5/2 + ) – 13.16 (7/2 + ) MeV, K = 3/2 + : 7.98 (3/2 + ) – 9.27 (5/2 + ) – 10.60 (7/2 + ) – 12.63 (9/2 + ) MeV, K = 5/2 + : 7.29 (5/2 + ) – 9.19 (7/2 + ) – 11.27 (9/2 + ) MeV. The moments of inertia of these band states are close to the moment of inertia of the Hoyle state of 12 C. The determined radii, related to these bands, are 0.7 – 1.0 fm larger than the radius of the ground state, these values are close to the radius of the Hoyle state. Above-mentioned results are in agreement with existing predictions about various cluster structure of 11 B at high excitation energies [3, 4]. 1. A.N.Danilov, A.S.Demyanova et al. // Physics of Atomic Nuclei, in print. 2. A.N.Danilov et al. // Phys.Rev. C. 2009. V.80. 054603. 3. T.Suhara, Y. Kanada-En'yo // Phys. Rev. C. 2012 V.85. 054320. 4. H.Yamaguchi et al. // Phys. Rev. C. 2011. V.83. 034306. 5. A.A.Ogloblin et al. // EPJ Web of Conferences 2014. V.66. 02074. 66 SEARCH FOR STATES WITH ABNORMAL RADII IN 13 C Demyanova A.S. 1 , Danilov A.N. 1 , Ogloblin A.A. 1 , Belyaeva T.L. 2 , Goncharov S.A. 3 , Trzaska W. 4 , Janseitov D. 5 1 Russian Research Center “Kurchatov Institute”, Moscow, Russia; 2 Universidad Autonoma del Estado de Mexico, Toluca, Mexico; 3 Lomonosov Moscow State University,Moscow, Russia; 4 The Accelerator Laboratory of the Department of Physics of the University of Jyväskylä, Jyvaskula, Finland; 5 L.N.Gumilyov Eurasian National University, Astana, Kazakhstan E-mail: a.s.demyanova@bk.ru In our previous experiment on the inelastic scattering 13 C (α,α’) at E(α) = 65 MeV [1] we claimed the observation of three excited states whose radii differed from that of the ground state: 3.09 MeV (1/2 + ), 8.86 MeV (1/2¯) and 9.90 MeV (3/2¯). In this paper we continued the analysis including in it some other data. The evaluation of radius of the 3.09 MeV state was performed by three independent methods, Modified diffraction model (MDM) [2], Nuclear rainbow method (NRM) [3, 4] and method using the asymptotic normalization coefficients (ANC) [5, 6]. The radius occurred to be enhanced in good agreement with theoretical predictions [7] demonstrating the existence of a neutron halo in this state. All three approaches gave similar values verifying the validity of the used methods. Application of MDM and NRM to the 8.86 MeV state showed that the latter also has an enhanced radius close to that of the Hoyle state (7.65 MeV, 0 + ) of 12 C [2]. The radius value of the 9.90 MeV remains an open question. The estimates done both by MDM and NRM methods gave the value less than that of the ground state. As this state is considered to be the head of the 3/2¯ rotational band [8], and its enhanced radius is predicted [9] a more elaborate analysis of the problem is required. Because of the importance of the obtained result new measurements of the inelastic scattering 13 C (α,α’) at E(α) = 90 MeV were performed. The analysis is in progress. 1. A.S.Demyanova et al. // EPJ Web of Conferences 2014. V.66. 02027. 2. A.N.Danilov et al. // Phys. Rev. C. 2009. V.80. 054603. 3. S.Ohkubo, Y.Hirabayashi // Phys. Rev. C. 2007. V.75. 044609. 4. A.S.Demyanova et al. // Int. J. Mod. Phys. E. 2011. V.20. №4. P.915. 5. Z.H.Liu et al. // Phys. Rev. C. 2001. V.64. 034312. 6. T.L.Belyaeva et al. // Phys.Rev. C. 2014. V.90. 064610-1. 7. T.Yamada, Y.Funaki // Int. J. Mod. Phys. E. 2008. V.17. P.2101. 8. M. Milin, W.von Oertzen // Eur. Phys. J. A. 2002. V.14. P.295. 9. N.Furutachi, M.Kimura // Phys. Rev. C. 2011. V.83. 021303. |
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