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Sample records for hot fragmenting nuclei

  1. Hot nuclei and fragmentation

    International Nuclear Information System (INIS)

    Guerreau, D.

    1993-01-01

    A review is made of the present status concerning the production of nuclei above 5 MeV temperature. Considerable progress has been made recently on the understanding of the formation and the fate of such hot nuclei. It appears that the nucleus seems more stable against temperature than predicted by static calculations. However, the occurrence of multifragment production at high excitation energies is now well established. The various experimental features of the fragmentation process are discussed. (author) 59 refs., 12 figs

  2. Complex fragment emission from hot compound nuclei

    International Nuclear Information System (INIS)

    Moretto, L.G.

    1986-03-01

    The experimental evidence for compound nucleus emission of complex fragments at low energies is used to interpret the emission of the same fragments at higher energies. The resulting experimental picture is that of highly excited compound nuclei formed in incomplete fusion processes which decay statistically. In particular, complex fragments appear to be produced mostly through compound nucleus decay. In the appendix a geometric-kinematic theory for incomplete fusion and the associated momentum transfer is outlined. 10 refs., 19 figs

  3. The decay of hot nuclei

    International Nuclear Information System (INIS)

    Moretto, L.G.; Wozniak, G.J.

    1988-11-01

    The formation of hot compound nuclei in intermediate-energy heavy ion reactions is discussed. The statistical decay of such compound nuclei is responsible for the abundant emission of complex fragments and high energy gamma rays. 43 refs., 23 figs

  4. Multifragmentation of hot nuclei

    International Nuclear Information System (INIS)

    Tamain, B.

    1990-10-01

    It is difficult to deposit a large amount (∼ 1 Gev) of excitation energy into a nucleus. And if one wants to deposit large excitation energy values, the best way consists of shooting a given target nucleus with several nucleons, which can be achieved by using intermediate energy (10-100 MeV/nucleon) heavy ions. Such very excited objects were named hot nuclei. The study of hot nuclei has been undertaken only for 7 years because intermediate energy heavy ion facilities were not available before. The game is then to determine the decay properties of such nuclei, their limits of existence. Their study is connected with general properties of nuclear matter: namely its equation of state. Of special interest, is the onset of a new decay mechanism: multifragmentation, which is the non-sequential disassembly of a hot nucleus into several light nuclei (often called intermediate-mass fragments or IMF) or particles. This paper, shows how this mechanism can reflect fundamental properties of nuclear matter, but also how its experimental signature is difficult to establish. Multifragmentation has also been studied by using very energetic projectiles (protons and heavy ions) in the relativistic or ultra-relativistic region. The multifragmentation question of hot nuclei is far from being solved. One knows that IMF production increases when the excitation energy brought into a system is strongly increased, but very little is known about the mechanisms involved and a clear onset for multifragmentation is not established

  5. Non-equilibrium versus equilibrium emission of complex fragments from hot nuclei

    International Nuclear Information System (INIS)

    Viola, V.E.; Kwiatkowski, K.; Yennello, S.; Fields, D.E.

    1989-01-01

    The relative contributions of equilibrium and non-equilibrium mechanisms for intermediate-mass fragment emission have been deduced for Z=3-14 fragments formed in 3 He- and 14 N-induced reactions on Ag and Au targets. Complete inclusive excitation function measurements have been performed for 3 He projectiles from E/A=67 to 1,200 MeV and for 14 N from E/A=20 to 50 MeV. The data are consistent with a picture in which equilibrated emission is important at the lowest energies, but with increasing bombarding energy the cross sections are increasingly dominated by non-equilibrium processes. Non-equilibrium emission is also shown to be favored for light fragments relative to heavy fragments. These results are supported by coincidence studies of intermediate-mass fragments tagged by linear momentum transfer measurements

  6. Fragmentation of relativistic nuclei

    International Nuclear Information System (INIS)

    Cork, B.

    1975-06-01

    Nuclei with energies of several GeV/n interact with hadrons and produce fragments that encompass the fields of nuclear physics, meson physics, and particle physics. Experimental results are now available to explore problems in nuclear physics such as the validity of the shell model to explain the momentum distribution of fragments, the contribution of giant dipole resonances to fragment production cross sections, the effective Coulomb barrier, and nuclear temperatures. A new approach to meson physics is possible by exploring the nucleon charge-exchange process. Particle physics problems are explored by measuring the energy and target dependence of isotope production cross sections, thus determining if limiting fragmentation and target factorization are valid, and measuring total cross sections to determine if the factorization relation, sigma/sub AB/ 2 = sigma/sub AA/ . sigma/sub BB/, is violated. Also, new experiments have been done to measure the angular distribution of fragments that could be explained as nuclear shock waves, and to explore for ultradense matter produced by very heavy ions incident on heavy atoms. (12 figures, 2 tables)

  7. Excited nuclei fragmentation

    International Nuclear Information System (INIS)

    Ngo, C.

    1986-11-01

    Experimental indications leading to the thought of a very excited nucleus fragmentation are resumed. Theoretical approaches are briefly described; they are used to explain the phenomenon in showing off they are based on a minimum information principle. This model is based on time dependent Thomas-Fermi calculation which allows the mean field effect description, and with a site-bound percolation model which allows the fluctuation description [fr

  8. Monopole transitions in hot nuclei

    International Nuclear Information System (INIS)

    Sujkowski, Z.

    1994-01-01

    Monopole transitions can be a signature of shape changing in a hot, pulsating nucleus (the low energy E0 mode) and/or a measure of the compressibility of finite nuclei (GMR, the breathing mode). Experimental information pertaining to GMR is reviewed. Recipes for deducing the incompressibility modules for infinite nuclear matter from data on GMR are discussed. Astrophysical implications are outlined. The first attempts at locating the GMR strength in moderately hot nuclei are described. Prospects for improving the experimental techniques to make an observation of this strength in selected nuclei unambiguous are discussed. (author). 46 refs, 8 figs

  9. Monopole transitions in hot nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Sujkowski, Z. [Soltan Inst. for Nuclear Studies, Otwock-Swierk (Poland)

    1994-12-31

    Monopole transitions can be a signature of shape changing in a hot, pulsating nucleus (the low energy E0 mode) and/or a measure of the compressibility of finite nuclei (GMR, the breathing mode). Experimental information pertaining to GMR is reviewed. Recipes for deducing the incompressibility modules for infinite nuclear matter from data on GMR are discussed. Astrophysical implications are outlined. The first attempts at locating the GMR strength in moderately hot nuclei are described. Prospects for improving the experimental techniques to make an observation of this strength in selected nuclei unambiguous are discussed. (author). 46 refs, 8 figs.

  10. Static and dynamical properties of hot nuclei

    International Nuclear Information System (INIS)

    Suraud, E.

    1990-01-01

    We briefly review our understanding of the formation of excited/hot nuclei in heavy-ion collisions at some tens of MeV/A. We recall the major theoretical frameworks used for describing as well the entrance channel of the reaction as the structure properties of hot nuclei. We finally focus on multifragmentation within insisting upon the theoretical challenge it does represent

  11. Formation and decay of hot nuclei

    International Nuclear Information System (INIS)

    Planeta, R.

    1999-01-01

    Multifragmentation of excited nuclei of the 40 Ca + 40 Ca reaction at 35 MeV/nucleon has been studied using the multidetector system AMPHORA.Using special gating and reconstruction procedures we have observed projectile - like fragments, PLF, with different degrees of excitation, and also highly excited composite systems, CS, from incomplete fusion. This reconstruction procedure was verified by the Monte Carlo computer code of Sosin which describes the collision of heavy ions as a random walk transfer of nucleons. Agreement between the experimental data and the predictions of the code have strongly supported the thermalized character of the created hot sources. To investigate their decay characteristics we have used the conventional reduced velocity correlation method and also two signatures based on special features of particle emission from the 'freeze out volume'. They are: (i) - the distribution of the squared momentum of the heaviest emitted fragment; (ii) - the focusing of fragments by the Coulomb field of the decaying system. For the PLF, both methods, the reduced velocity correlation, and the distribution of the squared momentum of the heaviest emitted fragment, support the binary sequential decay, BSD, scenario below 3 MeV/nucleon excitation energy and prompt multifragmentation, PM, for higher excitations. For CS which has about twice the PLF electric charge the Coulomb focusing effect could be also observed. In that case all three signatures indicate prompt multifragmentation of the system contained inside the 'freeze-out' volume. Consistency of all these observations show that both the distribution of the squared momentum of the heaviest emitted fragment and the Coulomb focusing effect can be used as signatures of spinodal decomposition of 'hot' nuclear systems. (author)

  12. Formation and decay of hot nuclei

    International Nuclear Information System (INIS)

    Tamain, B.

    1992-09-01

    The mechanisms involved in hot nuclei formation and decay and their eventual connexion with fundamental properties of nuclear matter are discussed, i.e. its equation of state is considered. After a brief review of the reactions in which hot nuclei can be formed, the variables which are used to describe them, the corresponding theoretical descriptions and their limits when extreme states are reached are discussed. Experimental evidences for hot nuclei formation are presented, with the corresponding decay properties used as signatures. (R.P.) 64 refs.; 25 figs.; 2 tabs

  13. Hot nuclei: high temperatures, high angular momenta

    International Nuclear Information System (INIS)

    Guerreau, D.

    1991-01-01

    A review is made of the present status concerning the production of hot nuclei above 5 MeV temperature, concentrating mainly on the possible experimental evidences for the attainment of a critical temperature, on the existence of dynamical limitations to the energy deposition and on the experimental signatures for the formation of hot spinning nuclei. The data strongly suggest a nuclear disassembly in collisions involving very heavy ions at moderate incident velocities. Furthermore, hot nuclei seem to be quite stable against rotation on a short time scale. (author) 26 refs.; 12 figs

  14. Antiproton Induced Fission and Fragmentation of Nuclei

    CERN Multimedia

    2002-01-01

    The annihilation of slow antiprotons with nuclei results in a large highly localized energy deposition primarily on the nuclear surface. \\\\ \\\\ The study of antiproton induced fission and fragmentation processes is expected to yield new information on special nuclear matter states, unexplored fission modes, multifragmentation of nuclei, and intranuclear cascades.\\\\ \\\\ In order to investigate the antiproton-nucleus interaction and the processes following the antiproton annihilation at the nucleus, we propose the following experiments: \\item A)~Measurement of several fragments from fission and from multifragmentation in coincidence with particle spectra, especially neutrons and kaons. \\item B)~Precise spectra of $\\pi$, K, n, p, d and t with time-of-flight techniques. \\item C)~Installation of the Berlin 4$\\pi$ neutron detector with a 4$\\pi$ Si detector placed inside for fragments and charged particles. This yields neutron multiplicity distributions and consequently distributions of thermal excitation energies and...

  15. Rotating bubble and toroidal nuclei and fragmentation

    International Nuclear Information System (INIS)

    Royer, G.; Haddad, F.; Jouault, B.

    1995-01-01

    The energy of rotating bubble and toroidal nuclei predicted to be formed in central heavy-ion collisions at intermediate energies is calculated within the generalized rotating liquid drop model. The potential barriers standing in these exotic deformation paths are compared with the three dimensional and plane fragmentation barriers. In the toroidal deformation path of the heaviest systems exists a large potential pocket localised below the plane fragmentation barriers. This might allow the temporary survival of heavy nuclear toroids before the final clusterization induced by the surface and proximity tension. (author)

  16. Hot nuclei, limiting temperatures and excitation energies

    International Nuclear Information System (INIS)

    Peter, J.

    1986-09-01

    Hot fusion nuclei are produced in heavy ion collisions at intermediate energies (20-100 MeV/U). Information on the maximum excitation energy per nucleon -and temperatures- indicated by the experimental data is compared to the predictions of static and dynamical calculations. Temperatures around 5-6 MeV are reached and seem to be the limit of formation of thermally equilibrated fusion nuclei

  17. Nuclear fragmentation for Xe+Au and Xe+Ag systems at an energy of 44 A.MeV, formation and decay of hot nuclei; Etude de la fragmentation nucleaire pour les systemes XE+AU et XE+AG a 44 A.MeV, production et decroissance de noyaux chauds

    Energy Technology Data Exchange (ETDEWEB)

    Meslin, C.

    1995-01-01

    A study of the formation and the decay of hot nuclear fragments produced in the reactions Xe+Au and Xe+Ag at an energy of 44 A.MeV is presented in this thesis. The 4{pi} experimental setup consisted of four multidetectors -two for the detection of the fragments (Z>7; DELF and XYZT) and two for the detection of the charged particles (Z<6; MUR and TONNEAU) and allowed an analysis using ``complete events`` (80 % of the total charge and the total parallel linear momentum of the entrance channel) to be carried out. The reaction mechanism is binary with as observed at low energy an almost complete relaxation of the incident energy. The collision results in two hot fragments at the beginning of the exit channel which decay by evaporation and/or fragmentation. In addition of these two body events, we have identified a new dynamic mechanism where we detect a small fragment, called the neck, coming form the overlap of the nuclei during the interaction, in coincidence with a projectile-like fragment and a target-like fragment. For the most dissipative collisions, the deep inelastic collision have allowed an estimation of the lifetime of the hot nuclear fragments to be made. This is possible using proximity effects and fragment-fragment space-time correlations of the decay of one or two primary partners from the deep inelastic collisions. This method is seen to reach its limits in the case of the reactions studied here. (authors). 61 refs.

  18. Isospin effects and hot nuclei

    International Nuclear Information System (INIS)

    Gagnon-Moisan, Francis

    2010-01-01

    The rapid decomposition (t≤10 -21 seconds) of a nucleus into multiple fragments, named multifragmentation, is associated to a liquid-gas phase transition. For many years, physicists have tried to obtain an experimental proof of this behaviour. It has been suggested that, to achieve this, one could observe the particular signature of the mechanism of such a transition: the spinodal decomposition, through the production of equal size fragments. A method is that of charge correlation using intrinsic probabilities. The 5. campaign for the INDRA multidetector which took place at GANIL was aimed at obtaining a high number of events, in order to sign the spinodal decomposition with a high confidence level. The chosen systems were 124 Xe+ 112 Sn and 136 Xe+ 124 Sn at beam energies of 32 and 45 AMeV. The acquired statistics allowed to confirm the existence of events with very narrow charge distributions, which agrees with the spinodal decomposition hypothesis. The study of 124 , 136 Xe+ 112 , 124 Sn at 32 and 45 AMeV shows the impact of neutron density on the exit channel: a neutron-rich system produces more fragments and fewer particles than a system initially neutron-poor. Finally, the modification on 27 modules from the INDRA multidetector allows the isotopic resolution of fragments up to oxygen (Z=8). This provides the information required for the study of the N/Z ratio of fragments versus their kinetic energy with the goal of obtaining an experimental constraint on the symmetry term of the equation of state. (author)

  19. The formation and deexcitation of hot nuclei in 40Ar + 197Au collisions at 44 and 77 MeV/A. Neutrons emission light charged particles and complex fragments

    International Nuclear Information System (INIS)

    Sokolov, A.

    1990-05-01

    This work is a contribution to the study of the formation and decay of hot nuclei produced in heavy ion collisions at intermediate energies. By studying the system Ar + Au and Ar + Th at 44 MeV/u and 77 MeV/u we first show how to classify events in two groups: peripheral and very dissipative collisions, measuring the number of evaporated neutrons, which depend directly on the violence of the collision. Associated with these neutrons, different deexcitation channels were observed (heavy residues, fission fragments, light charged particles, intermediate mass fragments). The ratio between peripheral and very dissipative collisions was found independent of the system and the same as the one observed at lower incident energy. The most probable neutron multiplicity for very dissipative collisions is not very different at 44 MeV/u and 77 MeV/u. A measurement of the angular distribution of fission fragments and heavy residues was performed. Detected products are essentially associated with large neutron multiplicity and have a cross section close to the one for the very dissipative collisions. The total mass of the fission fragments is close to the mass of the target, while the mass of the heavy residue is much smaller. The backward evaporated light charged particles are also produced in very dissipative collisions. The characteristics of their energy spectra as well as their multiplicities are very similar at 44 MeV/u 77 MeV/u. From the number of evaporated light charged particles, the estimation of the quasi-target excitation energy was done and found to be close to 600 MeV at 44 MeV/u and 77 MeV/u [fr

  20. Liquid drop parameters for hot nuclei

    International Nuclear Information System (INIS)

    Guet, C.; Strumberger, E.; Brack, M.

    1988-01-01

    Using the semiclassical extended Thomas-FERMI (ETF) density variational method, we derived selfconsistently the liquid drop model (LDM) coefficients for the free energy of hot nuclear systems from a realistic effective interaction (Skyrme SkM*). We expand the temperature (T) dependence of these coefficients up to the second order in T and test their application to the calculation of the fission barriers of the nuclei 208 Pb and 240 Pu

  1. Production and de excitation of hot nuclei

    International Nuclear Information System (INIS)

    Auger, F.; Faure, B.; Wirleczki, J.P.; Cunsolo, A.; Foti, A.; Plagnol, E.

    1988-01-01

    We studied Kr induced reactions on C, Al and Ti at 26.4, 34.4 and 45.4 MeV/nucleon. The aims of these experiments were to learn about the influence of the incident energy and asymmetry of the system on the incomplete fusion mechanism, that is on the characteristics (E,l) of the nuclei formed in the reactions and on the competition between massive transfer and preequilibrium emission. We also wanted to study the influence of excitation energy and angular momentum of the nuclei on their deexcitation modes, specially on the competition between light particles (n, p, α) and complex fragments (M>4). Considering the available energies (2.8 < ε < 10.5 MeV/nucleon), the grazing and the total masses (96 ≤ M ≤ 132), nuclei with masses around 100 are likely to be formed with very different excitation energies and angular momenta

  2. Birth, life and death of hot nuclei

    International Nuclear Information System (INIS)

    Suraud, E.; Tamain, B.; Gregoire, C.

    1989-01-01

    Intermediate energy heavy-ions (10-100 MeV/u) are the most powerful tool to study hot nuclear matter properties. In this paper we give a review of experimental and theoretical works which support this statement. The first challenge is to achieve hot nuclei formation. The second one is to study their properties. The formation step is governed by the relative influence of nucleon-nucleon collisions and mean field effects. Fundamental quantities such as excited matter decay time, thermalization time, relaxation time for collective modes are of major importance and are compared with typical collision times. It appears that semi-classical theories are able to give a reasonable description of the collision and that they are a good guide for defining further experiments. We show how it has been possible to experimentally establish that very hot equilibrated nuclei are really formed. Their decay properties are not basically different from decay properties at lower bombarding energy. However specific channels are open: in that sense, we take stock of the multifragmentation process. Moreover, compression effects may be an important feature of this energy range. Future studies will involve heavier projectiles around 30-50 MeV/u. They will be the best probe for hot and compressed nuclear matter studies

  3. Giant dipole resonance in hot nuclei

    International Nuclear Information System (INIS)

    Mau, N.V.

    1993-01-01

    Giant resonances built on an excited state of the nucleus at a finite temperature T are studied. The following questions are investigated: how long such collective effects occur in a nucleus when T increases. How the properties of the giant resonances vary when the temperature increases. How the study of giant resonances in hot nuclei can give information on the structure of the nucleus in a highly excited state. The special case of the giant dipole resonance is studied. Some of the experimental results are reviewed and in their theoretical interpretation is discussed. (K.A.). 56 refs., 20 figs., 4 tabs

  4. Giant resonances in hot rotating nuclei

    International Nuclear Information System (INIS)

    Ring, P.

    1992-01-01

    Present theoretical descriptions of the giant resonances in hot rotating nuclei are reviewed. Mean field theory is used as a basis for the description of the hot compound states. Starting from the static solution at finite temperature and with fixed angular momentum small amplitude collective vibrations are calculated in the frame work of finite temperature random phase approximation for quasi-particles. The effect of pairing at low temperatures as well as the effect of rotations on the position of the resonance maxima are investigated. Microscopic and phenomenological descriptions of the damping mechanisms are reviewed. In particular it turns out that fluctuations play an important role in understanding of the behaviour of the width as a function of the temperature. Motional narrowing is critically discussed. (author). 99 refs., 5 figs

  5. Approximate particle number projection in hot nuclei

    International Nuclear Information System (INIS)

    Kosov, D.S.; Vdovin, A.I.

    1995-01-01

    Heated finite systems like, e.g., hot atomic nuclei have to be described by the canonical partition function. But this is a quite difficult technical problem and, as a rule, the grand canonical partition function is used in the studies. As a result, some shortcomings of the theoretical description appear because of the thermal fluctuations of the number of particles. Moreover, in nuclei with pairing correlations the quantum number fluctuations are introduced by some approximate methods (e.g., by the standard BCS method). The exact particle number projection is very cumbersome and an approximate number projection method for T ≠ 0 basing on the formalism of thermo field dynamics is proposed. The idea of the Lipkin-Nogami method to perform any operator as a series in the number operator powers is used. The system of equations for the coefficients of this expansion is written and the solution of the system in the next approximation after the BCS one is obtained. The method which is of the 'projection after variation' type is applied to a degenerate single j-shell model. 14 refs., 1 tab

  6. Topology of White Stars in Relativistic Fragmentation of Light Nuclei

    CERN Document Server

    Andreeva, N P; Vokal, S; Vokalova, A; Gaitinov, A Sh; Gerassimov, S G; Goncharova, L A; Dronov, V A; Zarubin, P I; Zarubina, I G; Kovalenko, A D; Kravchakova, A; Larionova, V G; Levitskaja, O V; Lepehin, F G; Malakhov, A I; Moiseenko, A A; Orlova, G I; Peresadko, N G; Polukhina, N G; Rukojatkin, P A; Rusakova, V V; Salmanova, N A; Sarkisian, V R; Simonov, B B; Stan, E; Stanoeva, R; Chernyavsky, M M; Haidue, M; Kharlamov, S P; Tsakov, I; Shchedrina, T V

    2004-01-01

    In the present paper, experimental observation of the multifragmentation processes of light relativistic nuclei carried out by means of emulsions are reviewed. Events of the type of "white stars" in which the dissociation of relativistic nuclei is not accompanied by the production of mesons and the target-nucleus fragments are considered. A distinctive feature of the charge topology in the dissociation of the Ne, Mg, Si and S nuclei is an almost total suppression of the binary splitting of nuclei to fragments with charges higher than 2. The growth of the nuclear fragmentation degree is revealed in an increase in the multiplicity of singly and doubly charged fragments with decreasing charge of the main non-excited part of the fragmenting nucleus. The processes of dissociation of stable Li, Be, B, C, N, and O isotopes to charged fragments were used to study special features of the formation of systems consisting of the lightest nuclei - alpha, d and t. Clustering of the 3He nucleus can be detected in "white sta...

  7. Fragmentation of Relativistic 56Fe Nuclei in Emulsion

    International Nuclear Information System (INIS)

    Chernov, G.M.; Gulamov, K.G.; Gulyamov, U.G.; Navotny, V.Sh.; Petrov, N.V.; Svechnikova, L.N.; Jakobsson, B.; Oskarsson, A.; Otterlund, I.

    1983-03-01

    Experimental data on general characteristics of projectile fragments in inelastic interactions of relativistic 56 Fe nuclei in emulsion (multiplicities, transverse momentum distributions, azimuthal correlations) are presented and discussed. A strong dependence on the mass number of the projectile nucleus is observed for the transverse momenta of the emitted projectile fragments. These fragments exhibit an azimuthal asymmetry caused by the transverse motion of the fragmenting residue, but it is shown that this motion can be responsible only for a part of the increase in the average transverse momentum of the fragments with increasing mass of the projectile. (author)

  8. Imaging of Nuclear Fragmentation in Nuclear Track Emulsion Relativistic Nuclei

    International Nuclear Information System (INIS)

    Zarubina, I.G. JINR

    2011-01-01

    The method of nuclear track emulsion provides a uniquely complete observation of multiple fragment systems produced in dissociation of relativistic nuclei. The most valuable events of coherent dissociation of nuclei in narrow jets of light and the lightest nuclei with a net charge as in the initial nucleus, occurring without the production of fragments of the target nuclei and mesons (the so-called w hite s tars), comprise a few percent among the observed interactions. The data on this phenomenon are fragmented, and the interpretation is not offered. The dissociation degree of light O, Ne, Mg and Si, and as well as heavy Au, Pb and U nuclei may reach a complete destruction to light and the lightest nuclei and nucleons, resulting in cluster systems of an unprecedented complexity. Studies with relativistic neutron-deficient nuclei have special advantages due to more complete observations. An extensive collection of macro videos of such interactions in nuclear track emulsion gathered by the Becquerel collaboration is presented

  9. Probing the hot zone of colliding nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Elmer, R Aa

    1995-11-01

    The hot zone created in intermediate energy heavy ion collisions has been studied. At energies between 20 A MeV and 300 A MeV the nuclear emulsion technique has been used to achieve a full 4 pi identification and momentum determination of all charged fragments, enabling a strict selection of central events based on multiplicity and the energy flow tensor. In connection with this a CCD-based track identification system has been developed, specially designed for charge identification of intermediate-mass fragments. The CCD-camera is connected to an image processing card in a microcomputer where the width of the track is determined by profile measurements on the pixel level. The results point to a presence of radial flow in central {sup 36}Ar + AgBr collisions at 65 A MeV, but not in {sup 16}O + AgBr collisions at 210 A MeV. At energies between 0.8 to 1.8 A GeV mesons produced in symmetric Ne + NaF, Ni + Ni and Au + Au, have been measured by plastic scintillator counter telescopes. The mass and angular dependence of the subthreshold production of kaons at a laboratory energy of 1.0 A GeV have been systematically extracted from three different experiment periods at GSI, Darmstadt. The results point to the presence of rescattering of kaons in the dense nuclear environment, thus increasing the cross section at large angles. More speculatively, an anisotropy in the production process could be conjectured. 61 refs, 15 figs.

  10. Probing the hot zone of colliding nuclei

    International Nuclear Information System (INIS)

    Elmer, R.Aa.

    1995-11-01

    The hot zone created in intermediate energy heavy ion collisions has been studied. At energies between 20 A MeV and 300 A MeV the nuclear emulsion technique has been used to achieve a full 4 pi identification and momentum determination of all charged fragments, enabling a strict selection of central events based on multiplicity and the energy flow tensor. In connection with this a CCD-based track identification system has been developed, specially designed for charge identification of intermediate-mass fragments. The CCD-camera is connected to an image processing card in a microcomputer where the width of the track is determined by profile measurements on the pixel level. The results point to a presence of radial flow in central 36 Ar + AgBr collisions at 65 A MeV, but not in 16 O + AgBr collisions at 210 A MeV. At energies between 0.8 to 1.8 A GeV mesons produced in symmetric Ne + NaF, Ni + Ni and Au + Au, have been measured by plastic scintillator counter telescopes. The mass and angular dependence of the subthreshold production of kaons at a laboratory energy of 1.0 A GeV have been systematically extracted from three different experiment periods at GSI, Darmstadt. The results point to the presence of rescattering of kaons in the dense nuclear environment, thus increasing the cross section at large angles. More speculatively, an anisotropy in the production process could be conjectured. 61 refs, 15 figs

  11. Percolation versus microcanonical fragmentation - comparison of fragment size distribution: Where is the liquid-gas transition in nuclei?

    International Nuclear Information System (INIS)

    Jaqaman, H.R.; Birzeit Univ.; Papp, G.; Eoetvoes Lorand Tudomanyegyetem, Budapest; Gross, D.H.E.; Freie Univ. Berlin

    1990-01-01

    The distributions of fragments produced by microcanonical multifragmentation of hot nuclei are compared with the cluster distributions predicted by a bond percolation model on a finite lattice. The conditional moments of these distributions are used together with the correlations between the largest three fragments in each event. Whereas percolation and statistical nuclear fragmentation agree in many details as in the usual plots of the averaged moments of the fragment distributions which yield the critical exponents, they turn out to be essentially different when less averaged quantities or correlations are considered. The differences between the predictions of the two models are mainly due to the particularities of the nuclear problem, especially the effect of the long-range Coulomb force which favours the break-up of the highly excited nucleus into two large fragments (pseudo-fission) and, to a somewhat lesser extent, enhances the possibility for the cracking of the nucleus into more than two large fragments. The fission events are, however, clearly separated from a second branch of critical correlations which shows up clearly in both nuclear fragmentation and percolation. We think that this critical correlation branch is due to the liquid-gas phase transition in finite nuclei. (orig.)

  12. MCNP6 fragmentation of light nuclei at intermediate energies

    Energy Technology Data Exchange (ETDEWEB)

    Mashnik, Stepan G., E-mail: mashnik@lanl.gov [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Kerby, Leslie M. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); University of Idaho, Moscow, ID 83844 (United States)

    2014-11-11

    Fragmentation reactions induced on light target nuclei by protons and light nuclei of energies around 1 GeV/nucleon and below are studied with the latest Los Alamos Monte Carlo transport code MCNP6 and with its cascade-exciton model (CEM) and Los Alamos version of the quark-gluon string model (LAQGSM) event generators, version 03.03, used as stand-alone codes. Such reactions are involved in different applications, like cosmic-ray-induced single event upsets (SEU's), radiation protection, and cancer therapy with proton and ion beams, among others; therefore, it is important that MCNP6 simulates them as well as possible. CEM and LAQGSM assume that intermediate-energy fragmentation reactions on light nuclei occur generally in two stages. The first stage is the intranuclear cascade (INC), followed by the second, Fermi breakup disintegration of light excited residual nuclei produced after the INC. Both CEM and LAQGSM account also for coalescence of light fragments (complex particles) up to {sup 4}He from energetic nucleons emitted during INC. We investigate the validity and performance of MCNP6, CEM, and LAQGSM in simulating fragmentation reactions at intermediate energies and discuss possible ways of further improving these codes.

  13. Inclusive breakup of three-fragment weakly bound nuclei

    International Nuclear Information System (INIS)

    Carlson, B.V.; Frederico, T.; Hussein, M.S.

    2017-01-01

    The inclusive breakup of three-fragment projectiles is discussed within a four-body spectator model. Both the elastic breakup and the non-elastic breakup are obtained in a unified framework. Originally developed in the 80's for two-fragment projectiles such as the deuteron, in this paper the theory is successfully generalized to three-fragment projectiles. The expression obtained for the inclusive cross section allows the extraction of the incomplete fusion cross section, and accordingly generalizes the surrogate method to cases such as (t, p) and (t, n) reactions. It is found that two-fragment correlations inside the projectile affect in a conspicuous way the elastic breakup cross section. The inclusive non-elastic breakup cross section is calculated and is found to contain the contribution of a three-body absorption term that is also strongly influenced by the two-fragment correlations. This latter cross section contains the so-called incomplete fusion where more than one compound nuclei are formed. Our theory describes both stable weakly bound three-fragment projectiles and unstable ones such as the Borromean nuclei.

  14. Inclusive breakup of three-fragment weakly bound nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Carlson, B.V.; Frederico, T. [Instituto Tecnológico de Aeronáutica, DCTA, 12.228-900 São José dos Campos, SP (Brazil); Hussein, M.S., E-mail: hussein@if.usp.br [Instituto Tecnológico de Aeronáutica, DCTA, 12.228-900 São José dos Campos, SP (Brazil); Instituto de Estudos Avançados, Universidade de São Paulo, C.P. 72012, 05508-970 São Paulo, SP (Brazil); Instituto de Física, Universidade de São Paulo, C.P. 66318, 05314-970 São Paulo, SP (Brazil)

    2017-04-10

    The inclusive breakup of three-fragment projectiles is discussed within a four-body spectator model. Both the elastic breakup and the non-elastic breakup are obtained in a unified framework. Originally developed in the 80's for two-fragment projectiles such as the deuteron, in this paper the theory is successfully generalized to three-fragment projectiles. The expression obtained for the inclusive cross section allows the extraction of the incomplete fusion cross section, and accordingly generalizes the surrogate method to cases such as (t, p) and (t, n) reactions. It is found that two-fragment correlations inside the projectile affect in a conspicuous way the elastic breakup cross section. The inclusive non-elastic breakup cross section is calculated and is found to contain the contribution of a three-body absorption term that is also strongly influenced by the two-fragment correlations. This latter cross section contains the so-called incomplete fusion where more than one compound nuclei are formed. Our theory describes both stable weakly bound three-fragment projectiles and unstable ones such as the Borromean nuclei.

  15. Collective motion in hot superheavy nuclei

    NARCIS (Netherlands)

    Tveter, TS; Gaardhoje, JJ; Maj, A; Ramsoy, T; Atac, A; Bacelar, J; Bracco, A; Buda, A; Camera, F; Herskind, B; Korten, W; Krolas, W; Menthe, A; Million, B; Nifenecker, H; Pignanelli, M; Pinston, JA; vanderPloeg, H; Schussler, F; Sletten, G

    1996-01-01

    The superheavy nucleus (272)(108)Hs and its evaporation daughters have been produced using the reaction Th-232(Ar-40,gamma xn) with beam energies 10.5 and 15.0 MeV/A. The Giant Dipole Resonance gamma-radiation from the hot conglomerate system prior to fission has been isolated using a differential

  16. The decay of hot dysprosium nuclei

    International Nuclear Information System (INIS)

    Atac, A.; Rekstad, J.; Guttormsen, M.; Messelt, S.; Ramsoey, T.; Thorsteinsen, T.F.; Loevhoeiden, G.; Roedland, T.

    1987-03-01

    The γ-decay following the 162,163 Dy( 3 He,αxn) reactions with E 3 He =45 MeV has been studied. Non-statistical γ-radiation with energies of E γ ≅1 MeV and ≅2 MeV is found for various residual nuclei. The properties of these γ-ray bumps depend on the number of emitted neutrons and reveal an odd-even mass dependence. New techniques to extract average neutron energies as a function of excitation energy and of the number of emitted neutrons are employed. The deduced neutron energies are consistent with Fermi-gas model predictions

  17. About dynamic model of limiting fragmentation of heavy nuclei

    International Nuclear Information System (INIS)

    Kuchin, I.A.

    2001-01-01

    Full text: As is known, during last years defined progress in understanding of static aspect of a dynamic structure organization of massive nuclei was reached. The offered model of a 'crystalline' structure of the nucleus generalizes drop, shell and cluster models in a natural way. Now increased interest induces the phenomenon of limiting fragmentation of heavy nuclei. There is a hope, that clearing up the general regularities of a soft disintegration of the massive nuclei on nucleons, component it, in a broad range of high energies can give a valuable information about dynamics of origin of nuclear structures and nature of their qualitative difference from a quark system structure, i.e. from nucleons. The key for understanding the indicated phenomenon can be it's study in connection with other aspects of disintegration of the nuclei - Coulomb and diffraction dissociation, fission etc. The sequential analysis of all these a processes from a single point of view is possible only within the framework of results and methods of the dynamic system theory. The purpose of the present research is clearing up a possibility to understand the nature of limiting fragmentation as a consequence of development of dynamic instability in a system of the nuclei as a result of ions interaction at high energy. In the analysis we based on data of the phenomenological analysis of heavy ion interactions at ultra-relativistic energies obtained by many authors for a number of years. As a result we came to a conclusion about general stochastic nature of an investigated phenomenon. In it development the fragmentation passes three different stages. On the first there is a process of preparation of chaos at a quantum level in an outcome of a Coulomb dissociation of the approaching nuclei and isotopic recharge of their nucleons, carrying a random character. A dominant here - viscous dissociation of nuclei under an operation of Coulomb forces. (A two body initial state). Then the multiparticle

  18. Life-time of hot nuclei

    International Nuclear Information System (INIS)

    Aboufirassi, M.; Bougault, R.; Brou, R.; Colin, J.; Durand, D.; Genoux-Lubain, A.; Horn, D.; Laville, J.L.; Le Brun, C.; Lecolley, J.F.; Lopez, O.; Louvel, M.; Mahi, M.; Meslin, C.; Steckmeyer, J.C.; Tamain, B.

    1998-01-01

    The study of the systems Ne + Au, Ar + Au and Kr + Au has allowed description of the de-excitation and particularly the evolution of the fragment emission time intervals as o function of the compound system excitation energy. The analysis of data obtained by the multidetector NAUTILUS for Pb + Au at 29 MeV/u has permitted the access to another time scale: the lifetime of the two partners before fragmentation. For this system and this energy the predominant process is primarily a two-body process analogue to that observed at lower energies (deep inelastic transfer). This mechanism can lead to a complete relaxation energy and consequently to low relative velocities between the two partners in the exit channel. In contrast to the low energy process where the two partners decay by evaporation, here the energy implied may lead to the rupture of one and/or the other partner in several fragments (2 to 5). For the the most relaxed events the excitation energies may reach the values of 6 MeV/u. Simulations were realized in which the entrance channel i.e. the relaxation of the two partners is described by a classical trajectory calculation. In the exit channel after a time τ one of the two partners splits in several fragments. The study of the trajectories of these fragments allows the determination of the angular distributions relative to the direction of the un-split partner. The comparison between this calculation and the data is given. The τ values vary from a negative value corresponding to a rupture during the interaction of two partners up to a τ of 200 fm/c. The best fit indicates a τ 100 fm/c, this showing that the lifetime of the splitting nucleus is of the order of 100 fm/c after separation of the two partners. By comparing this result with microscopic models one can obtain a better understanding of the system rupture scenario. This study is under way

  19. Toroidal and rotating bubble nuclei and the nuclear fragmentation

    International Nuclear Information System (INIS)

    Royer, G.; Fauchard, C.; Haddad, F.; Jouault, B.

    1997-01-01

    The energy of rotating bubble and toroidal nuclei predicted to be formed in central heavy ion collisions at intermediate energies is calculated within the generalized rotating liquid drop model. Previously, a one-parameter shape sequence has been defined to describe the path leading to pumpkin-like configurations and toroidal shapes. New analytical expressions for the shape dependent functions have been obtained. The potential barriers standing in these exotic deformation paths are compared with the three-dimensional and plane-fragmentation barriers. Metastable bubble-like minima only appear at very high angular momentum and above the three dimensional fragmentation barriers. In the toroidal deformation path of the heaviest systems exists a large potential pocket localized below the plane-fragmentation barriers. This might allow the temporary survival of heavy nuclear toroids before the final clusterization induced by the surface and proximity tension

  20. Acoustic cavitation as a mechanism of fragmentation of hot molten droplets in in cool liquids

    International Nuclear Information System (INIS)

    Kazimi, M.; Watson, C.; Lanning, D.; Rohsenow, W.; Todreas, N.

    1976-11-01

    A mechanism that explains several of the observations of fragmentation of hot molten drops in coolants is presented. The mechanism relates the fragmentation to the development of acoustic cavitation and subsequent bubble growth within the molten material. The cavitation is assumed due to the severe pressure excursions calculated within the hot material as a result of the pressure pulses accompanying coolant vaporization at the sphere surface. The growth of the cavitation vapor nuclei inside the hot drop is shown to be influenced by the subsequent long duration surface pressure pulses. The variation of the amplitude of these surface pulses with experimental variables is shown to exhibit the same trends with these variables as does the variation in extent of fragmentation

  1. Giant dipole resonance in hot rotating nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Chakrabarty, D.R. [Bhabha Atomic Research Centre, Nuclear Physics Division, Mumbai (India); Dinh Dang, N. [RIKEN, Nishina Centre for Accelerator-based Science, Saitama (Japan); VINATOM, Institute of Nuclear Science and Technique, Hanoi (Viet Nam); Datar, V.M. [Tata Institute of Fundamental Research, INO Cell, Mumbai (India)

    2016-05-15

    Over the last several decades, extensive experimental and theoretical work has been done on the giant dipole resonance (GDR) in excited nuclei covering a wide range of temperature (T), angular momentum (J) and nuclear mass. A reasonable stability of the GDR centroid energy and an increase of the GDR width with T (in the range∝1-3 MeV) and J are the two well-established results. Some experiments have indicated the saturation of the GDR width at high T. The gradual disappearance of the GDR vibration at much higher T has been observed. Experiments on the Jacobi transition and the GDR built on superdeformed shapes at high rotational frequencies have been reported in a few cases. Theoretical calculations on the damping of the collective dipole vibration, characterised by the GDR width, have been carried out within various models such as the thermal shape fluctuation model and the phonon damping model. These models offer different interpretations of the variation of the GDR width with T and J and have met with varying degrees of success in explaining the experimental data. In this review, the present experimental and theoretical status in this field is discussed along with the future outlook. The interesting phenomenon of the pre-equilibrium GDR excitation in nuclear reactions is briefly addressed. (orig.)

  2. Dynamical instability of hot and compressed nuclei

    International Nuclear Information System (INIS)

    Ngo, C.; Leray, S.; Spina, M.E.; Ngo, H.

    1989-01-01

    The dynamical evolution of a hot and compressed nucleus is described by means of an extended liquid-drop model. Using only the continuity equation and the energy conservation we show that the system expands after a while. The possible global instabilities of the drop are studied by applying the general conditions of stability of dynamical systems. We find that the nucleus is unstable if it can reach a low density configuration (≅0.07 nucleon/fm 3 ). Such a configuration is obtained if the initial compression of the nucleus is large enough. It is shown that the thermal excitation energy has much less influence than the compressional energy. These instability conditions are in good agreement with those obtained previously within the framework of lattice percolation and the same model for the dynamical expansion. Since local instabilities may also very likely be present, we propose to study them using a restructured aggregation model. They lead to a multifragmentation of the system, a mechanism which is known experimentally to exist. We find that local instabilities occur at smaller (but very close) density values than global ones. A moment analysis of the calculated multifragmentation events allows to extract a critical exponent in excellent agreement with the one deduced experimentally from Au-induced reactions. (orig.)

  3. Heavy-residue isoscaling as a probe of the symmetry energy of hot fragments

    International Nuclear Information System (INIS)

    Souliotis, G.A.; Shetty, D.V.; Keksis, A.; Bell, E.; Jandel, M.; Veselsky, M.; Yennello, S.J.

    2006-01-01

    The isoscaling properties of isotopically resolved projectile residues from peripheral collisions of 86 Kr (25 MeV/nucleon) 64 Ni (25 MeV/nucleon), and 136 Xe (20 MeV/nucleon) beams on various target pairs are employed to probe the symmetry energy coefficient of the nuclear binding energy. The present study focuses on heavy projectile fragments produced in peripheral and semiperipheral collisions near the onset of multifragment emission (E * /A=2-3 MeV). For these fragments, the measured average velocities are used to extract excitation energies. The excitation energies, in turn, are used to estimate the temperatures of the fragmenting quasiprojectiles in the framework the Fermi gas model. The isoscaling analysis of the fragment yields provided the isoscaling parameters α that, in combination with temperatures and isospin asymmetries provided the symmetry energy coefficient of the nuclear binding energy of the hot fragmenting quasiprojectiles. The extracted values of the symmetry energy coefficient at this excitation energy range (2-3 MeV/nucleon) are lower than the typical liquid-drop model value ∼25 MeV corresponding to ground-state nuclei and show a monotonic decrease with increasing excitation energy. This result is of importance in the formation of hot nuclei in heavy-ion reactions and in hot stellar environments such as supernova

  4. The giant resonances in hot nuclei. Linear response calculations

    International Nuclear Information System (INIS)

    Braghin, F.L.; Vautherin, D.; Abada, A.

    1995-01-01

    The isovector response function of hot nuclear matter is calculated using various effective Skyrme interactions. For Skyrme forces with a small effective mass the strength distribution is found to be nearly independent of temperature, and shows little collective effects. In contrast effective forces with an effective mass close to unity produce at zero temperature sizeable collective effects which disappear at temperatures of a few MeV. The relevance of these results for the saturation of the multiplicity of photons emitted by the giant dipole resonance in hot nuclei observed in recent experiments beyond T = 3 MeV is discussed. (authors). 12 refs., 3 figs

  5. The Giant Dipole Resonance in hot nuclei. Experimental aspects

    International Nuclear Information System (INIS)

    Alamanos, N.; Auger, F.

    1994-12-01

    Some of the most recent experimental results on the GDR in hot nuclei are presented. All data on the γ-decay of the GDR show a saturation of the apparent width and a saturation of the yield. However, it is not clear until now, if these effects are related to a GDR width which either saturates or increases continuously with the excitation energy. Very new data associated to selected exit channels could help to clarify the situation. (author). 14 refs., 7 figs

  6. Fragmentation of single-particle states in deformed nuclei

    International Nuclear Information System (INIS)

    Malov, L.A.; Soloviev, V.G.

    1975-01-01

    Fragmentation of single-particle states on levels of deformed nuclei is studied on the example of 239 U and 169 Er nuclei in the framework of the model taking into consideration the interaction of quasiparticles with phonons. The dependence of fragmentation on the Fermi surface is considered from the viewpoint of single-particle levels. It is shown that in the distribution of single-particle strength functions a second maximum appears together with the large asymmetry maximum at high-energy excitation, and the distribution has a long ''tail''. A semimicroscopic approach is proposed for calculating the neutron strength functions. The following values of the strength functions are obtained: for sub(239)U-Ssub(0)sup(cal)=1.2x10sup(-4), Ssub(1)sup(cal)=2.7x10sub(-4) and for sub(169)Er-Ssub(0)sup(cal)=1.10sup(-4), Ssub(1)sup(cal)=1.2x10sup(-4)

  7. Measuring the temperature of hot nuclear fragments

    International Nuclear Information System (INIS)

    Wuenschel, S.; Bonasera, A.; May, L.W.; Souliotis, G.A.; Tripathi, R.; Galanopoulos, S.; Kohley, Z.; Hagel, K.; Shetty, D.V.; Huseman, K.; Soisson, S.N.; Stein, B.C.; Yennello, S.J.

    2010-01-01

    A new thermometer based on fragment momentum fluctuations is presented. This thermometer exhibited residual contamination from the collective motion of the fragments along the beam axis. For this reason, the transverse direction has been explored. Additionally, a mass dependence was observed for this thermometer. This mass dependence may be the result of the Fermi momentum of nucleons or the different properties of the fragments (binding energy, spin, etc.) which might be more sensitive to different densities and temperatures of the exploding fragments. We expect some of these aspects to be smaller for protons (and/or neutrons); consequently, the proton transverse momentum fluctuations were used to investigate the temperature dependence of the source.

  8. The decay of hot nuclei formed in La-induced reactions at intermediate energies

    International Nuclear Information System (INIS)

    Libby, B.; Mignerey, A.C.; Madani, H.; Marchetti, A.A.; Colonna, M.; DiToro, M.

    1992-01-01

    The decay of hot nuclei formed in lanthanum-induced reactions utilizing inverse kinematics has been studied from E/A = 35 to 55 MeV. At each bombarding energy studied, the probability for the multiple emission of complex fragments has been found to be independent of target. Global features (total charge, source velocity) of the reaction La + Al at E/A = 45 MeV have been reproduced by coupling a dynamical model to study the collision stage of the reaction to a statistical model of nuclear decay

  9. Predicting "Hot" and "Warm" Spots for Fragment Binding.

    Science.gov (United States)

    Rathi, Prakash Chandra; Ludlow, R Frederick; Hall, Richard J; Murray, Christopher W; Mortenson, Paul N; Verdonk, Marcel L

    2017-05-11

    Computational fragment mapping methods aim to predict hotspots on protein surfaces where small fragments will bind. Such methods are popular for druggability assessment as well as structure-based design. However, to date researchers developing or using such tools have had no clear way of assessing the performance of these methods. Here, we introduce the first diverse, high quality validation set for computational fragment mapping. The set contains 52 diverse examples of fragment binding "hot" and "warm" spots from the Protein Data Bank (PDB). Additionally, we describe PLImap, a novel protocol for fragment mapping based on the Protein-Ligand Informatics force field (PLIff). We evaluate PLImap against the new fragment mapping test set, and compare its performance to that of simple shape-based algorithms and fragment docking using GOLD. PLImap is made publicly available from https://bitbucket.org/AstexUK/pli .

  10. Decay of a hot zone in finite nuclei

    International Nuclear Information System (INIS)

    De, J.N.; Gregoire, C.

    1987-01-01

    Assuming that a hot zone is formed in nuclear collisions, we study its decay in the surrounding colder nuclear matter. Thermal equilibration resulting from energy transport is analyzed in terms of a classical model and within the Vlasov-Uehling-Uhlenbeck self-consistent approach. Convection is found to be the dominant energy propagation mode. Thermal equilibration time is found to be of the order of the damping of isoscalar quadrupole vibration, i.e. a few 10 -21 sec. This feature may not be fully consistent with recent available experimental data and casts doubt on the possibility of formation of a sharply localised thermally equilibrated hot zone as a likely intermediate state for excitation in finite nuclei in intermediate energy collisions. 16 refs

  11. Stochastic behavior of cooling processes in hot nuclei

    International Nuclear Information System (INIS)

    de Oliveira, P.M.; Sa Martins, J.S.; Szanto de Toledo, A.

    1997-01-01

    The collapse of structure effects observed in hot nuclei is interpreted in terms of a dynamic lattice model which describes the process of nucleon (clusters) evaporation from a hot nucleus, predicting the final mass distribution. Results are compared with experimental data for the 10 B+ 9 Be and 10 B+ 10 B reactions, and indicate that the structures observed in the low-energy mass distributions in both simulation and experiment are a consequence of the competition between the residual interactions and the thermalization dissipative process. As a characteristic feature of complex evolving systems, this competition leads to long term memory during the dissipative path, the observables becoming thus insensitive to the actual microscopic interactions. copyright 1997 The American Physical Society

  12. Formation and decay of hot nuclei: the experimental situation

    International Nuclear Information System (INIS)

    Guerreau, D.

    1989-01-01

    With the achievement of new facilities in the 80's providing us heavy ion beams well above the Coulomb barrier, a unique opportunity was offered to the experimentalists to produce and study nuclear matter under extreme conditions. Effectively, in the energy range 20-100 MeV/u, on which we will concentrate in these lectures, it appeared very rapidly that excited nuclei could be formed at rather high temperatures. These lectures are intended to give an overview of the experimental status in this ''hot'' domain. Other lectures are more focused on the theoretical point of view. This paper will be arranged as follows: In a first part, the conceptual problems one might have to face will be introduced. A long chapter will be then devoted to the different experimental methods used so far in order to characterize the hot nucleus. We shall then discuss what can be learned from the study of deexcitation of nuclei at high T. The fourth part will be focused on the experimental evidences for the existence of limiting temperatures. Finally, a brief discussion will follow related to possible clues for the onset of nuclear instabilities at this critical temperature

  13. Decay of Hot Nuclei at Low Spins Produced by Antiproton-Annihilation in Heavy Nuclei

    CERN Multimedia

    2002-01-01

    % PS208 \\\\ \\\\ The objective of the experiment is to study (i) the thermal excitation energy distribution of antiproton-induced reactions in heavy nuclei and (ii) the decay properties of hot nuclei at low spins via evaporation, multifragmentation and fission as a function of excitation energy. The experimental set-up consists of 4-$\\pi$ detectors: the Berlin Neutron Ball~(BNB) which is a spherical shell of gadolinium-loaded scintillator liquid with an inner and outer diameter of 40 and 160~cm, respectively. This detector counts the number of evaporated neutrons in each reaction. Inside BNB there is a 4-$\\pi$ silicon ball~(BSIB) with a diameter of 20~cm consisting of 162 detectors which measure energy and multiplicity of all emitted charged nuclear particles. The particles are identified via time of flight, energy and pulse shape correlations.

  14. Hot nuclei with high spin states in collisions between heavy nuclei

    International Nuclear Information System (INIS)

    Galin, J.

    1991-01-01

    In the first part of this contribution we have shown that pretty hot nuclei could be obtained in peripheral collisions of Kr+Au. The collisions considered in the chosen example give rise to a nucleus of Z=28 with a kinetic energy of 1600 MeV (i.e. a velocity close to 27 MeV/u to be compared with the 32 MeV/u of the beam). The excitation energy deposited in the non-detected target like-nucleus, deduced from the neutron multiplicity measurements, amounts to 700 MeV (T= 6 MeV). In the second part of the contribution one used the well known properties of fission, and particularly its sensitivity to spin, to show in a qualitative way that pretty high spin values are into play. A more quantitative analysis together with additional measurements are still needed in order to infer precise figures of spin. It can be noted that for the 29 MeV/u Pb+Au reaction 1 max amounts to 1700 ℎ. If we assume that the sticking or rolling conditions can be fulfilled for initial angular momenta of about 2/3 1 max , then a projectile-like (and its target partner) could acquire an intrinsic spin of about 160 ℎ. The behavior of a Pb-like nucleus brought in such an exotic state (T=6 MeV and J=160ℎ)) is certainly worth to be studied in detail. It is also worth recalling that, when obtained in peripheral collisions, the hot nuclei thus formed do not suffer much initial compression at variance with what happens in more central collisions. There is thus an interesting field to be explored of hot, high spin but uncompressed nuclei

  15. Formation and Decay of Hot Nuclei in Heavy Ion Collisions

    International Nuclear Information System (INIS)

    Planeta, R.; Gawlikowicz, W.; Grotowski, K.

    2000-01-01

    The properties of the multifragmentation of ''hot sources'' produced in the 40 Ca+ 40 Ca reaction have been studied at a beam energy 35 MeV/nucleon. Two signatures of prompt multifragmentation, which make use of special features of particle emission from the ''freeze out volume'', together with an analysis of the reduced relative velocity between pairs of intermediate mass fragments, indicate the presence of a transition from sequential decay to prompt multifragmentation at an excitation energy of about 3 MeV/nucleon. (author)

  16. Symmetric and asymmetric ternary fission of hot nuclei

    International Nuclear Information System (INIS)

    Siwek-Wilczynska, K.; Wilczynski, J.; Leegte, H.K.W.; Siemssen, R.H.; Wilschut, H.W.; Grotowski, K.; Panasiewicz, A.; Sosin, Z.; Wieloch, A.

    1993-01-01

    Emission of α particles accompanying fusion-fission processes in the 40 Ar + 232 Th reaction at E( 40 Ar) = 365 MeV was studied in a wide range of in-fission-plane and out-of-plane angles. The exact determination of the emission angles of both fission fragments combined with the time-of-flight measurements allowed us to reconstruct the complete kinematics of each ternary event. The coincident energy spectra of α particles were analyzed by using predictions of the energy spectra of the statistical code CASCADE . The analysis clearly demonstrates emission from the composite system prior to fission, emission from fully accelerated fragments after fission, and also emission during scission. The analysis is presented for both symmetric and asymmetric fission. The results have been analyzed using a time-dependent statistical decay code and confronted with dynamical calculations based on a classical one-body dissipation model. The observed near-scission emission is consistent with evaporation from a dinuclear system just before scission and evaporation from separated fragments just after scission. The analysis suggests that the time scale of fission of the hot composite systems is long (about 7x10 -20 s) and the motion during the descent to scission almost completely damped

  17. Fragmentation and Multifragmentation of 10.6 A GeV Gold Nuclei

    CERN Document Server

    Adamovich, M I

    1999-01-01

    We present the results of a study performed on the interactions of 10.6A GeV gold nuclei in nuclear emulsions. In a minimum bias sample of 1311 interac- tions, 5260 helium nuclei and 2622 heavy fragments were observed as Au projec- tile fragments. The experimental data are analyzed with particular emphasis of target separation interactions in emulsions and study of criticalexponents. Multiplicity distributions of the fast-moving projectile fragments are inves- tigated. Charged fragment moments, conditional moments as well as two and three -body asymmetries of the fast moving projectile particles are determined in terms of the total charge remaining bound in the multiply charged projectile fragments. Some differences in the average yields of helium nuclei and heavier fragments are observed, which may be attributed to a target effect. However, two and three-body asymmetries and conditional moments indicate that the breakup mechanism of the projectile seems to be independent of target mass. We looked for evidenc...

  18. Decay of hot nuclei produced by relativistic light ions

    International Nuclear Information System (INIS)

    Karnaukhov, V.A.; Avdeev, S.P.; Kuznetsov, V.D.

    1995-01-01

    In collisions of light relativistic projectiles (p, 4 He) with heavy nuclei (Au) very excited target spectators are created, which decay via multiple emission of intermediate mass fragments. It was found that the mean IMF multiplicities are equal (within 15%) to 2.0, 2.6 and 3.0 at proton energies 2.16, 3.6 and 8.1 GeV respectively. These values are comparable with those obtained with heavy ions in the same beam energy range. This is considered to indicate that this observable is not sensitive to the collision dynamics and is determined by the phase space factor. IMF energy spectra are described by the statistical model of multifragmentation neglecting dynamics of the expansion stage before the break up. The expansion velocity is estimated to be ≤ 0.02 c. The mean lifetime of a fragmentating system is found to be ≤ 75 fm/c from IMF-IMF-angular correlations for 4 He (14.6 GeV) +Au collisions. The results support a scenario of true 'thermal' multifragmentation. 26 refs., 10 figs., 1 tab

  19. MCNP6 Simulation of Light and Medium Nuclei Fragmentation at Intermediate Energies

    Energy Technology Data Exchange (ETDEWEB)

    Mashnik, Stepan Georgievich [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Kerby, Leslie Marie [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Univ. of Idaho, Moscow, ID (United States)

    2015-08-24

    Fragmentation reactions induced on light and medium nuclei by protons and light nuclei of energies around 1 GeV/nucleon and below are studied with the Los Alamos transport code MCNP6 and with its CEM03.03 and LAQGSM03.03 event generators. CEM and LAQGSM assume that intermediate-energy fragmentation reactions on light nuclei occur generally in two stages. The first stage is the intranuclear cascade (INC), followed by the second, Fermi breakup disintegration of light excited residual nuclei produced after the INC. CEM and LAQGSM account also for coalescence of light fragments (complex particles) up to sup>4He from energetic nucleons emitted during INC. We investigate the validity and performance of MCNP6, CEM, and LAQGSM in simulating fragmentation reactions at intermediate energies and discuss possible ways of further improving these codes.

  20. Fragments emission from light mass composite nuclei within collective clusterization mechanism

    International Nuclear Information System (INIS)

    Singh, BirBikram

    2016-01-01

    Based on the quantum mechanical fragmentation theory (QMFT) the dynamical cluster decay model (DCM) has been developed by Gupta and Collaborators to study the decay of hot and rotating compound systems. Number of compound nuclei (CN) in different mass regions have been studied quite extensively while taking into consideration nuclear structure effects in the same. It is quite relevant to mention here that in the binary decay of CN nuclear structure effects comes into picture, within DCM, via preformation probability P_0 of the complimentary fragments before penetrating the potential barrier between them with certain probability P . It is interesting to note here that the statistical models treat various decay modes of the CN on different footing contrary to the DCM. In very light mass region the decay of number of composite systems "2"0","2"1","2"2Ne*, "2"6"-"2"9Al, "2"8Si, "3"1P, "3"2S, "3"9K and "4"0Ca*, formed in low energy heavy ion reactions, have been investigated for different reaction mechanisms particularly fusion-fission (FF) and deep inelastic orbiting (DIO) from equilibrated and non-equilibrated compound nucleus processes, respectively

  1. Hot nuclei studies with a 4 π-Neutron detector

    International Nuclear Information System (INIS)

    Galin, J.; Crema, E.; Doubre, H.; Guerreau, D.; Jiang, D.X.; Morjean, M.; Piasecki, E.; Pouthas, J.; Saint-Laurent, F.; Sokolov, A.; Wang, X.D.; Charvet, J.L.; Frehaut, J.; Lott, B.; Magnago, C.; Patin, Y.; Gatty, B.; Jacquet, D.; Lott, B.

    1989-01-01

    When studying the behavior of hot nuclei, the challenge is twofold: how are they formed in nucleus-nucleus collisions and how do they decay Systematic studies have been undertaken at GANIL by bombarding heavy targets (Au, Th) with intermediate energy projectiles (27, 35, 44 and 77 MeV/u Ar and 32 MeV/u Kr). For such neutron rich systems the thermalized energy can be roughly evaluated simply by measuring the multiplicity of evaporated neutrons using a 4 π Gd loaded, liquid scintillator detector. The influence of the bombarding energy and projectile mass on the energy dissipation has been investigated for different exit channels and special emphasis has been put in the study of the most dissipative collisions. The thermal energy, derived by summing the energy removed by both evaporated neutrons and light charged particles is shown to saturate at E * ≅ 650 MeV in the Ar induced reactions between 27 and 77 MeV/u, in good consistency with the predictions of semi-classical Landau-Vlasov calculations

  2. Influence of complex particle emission on properties of giant dipole resonance of hot nuclei

    International Nuclear Information System (INIS)

    Wen Wanxin; Jin Genming

    2003-01-01

    The possible reasons for the discrepancy between calculation results based on the statistical evaporation model and experimental data of giant dipole resonance of very hot nuclei are discussed. Both of simulations with the standard CASCADE code and the code coupling complex particle emission are carried out. It is shown that the complex particle emission affects the properties of giant dipole resonance of very hot nuclei

  3. Spherical time dependent Thomas-Fermi calculation of the dynamical evolution of hot and compressed nuclei

    International Nuclear Information System (INIS)

    Nemeth, J.; Barranco, M.; Ngo, C.; Tomasi, E.

    1985-01-01

    We have used a self-consistent time dependent Thomas-Fermi model at finite temperature to calculate the dynamical evolution of hot and compressed nuclei. It has been found that nuclei can accomodate more thermal energy than compressional energy before they break. (orig.)

  4. Momentum characteristics of spectators in fragmentation of 4He nuclei

    International Nuclear Information System (INIS)

    Glagolev, V.V.; Lebedev, R.M.; Strel'tsov, V.N.

    1985-01-01

    Some characteristics of 2 H, 3 H, 3 He fragments from 4 Hep interaction at 8.6 GeV/c have been studied. A numerical procedure, based on Monte-Carlo method, for getting the wave function of relative motion of nucleons or groups of nucleons in nucleus is proposed to describe the fragment momentum spectra and the asymmetry in Treiman-Yang angle distribution. The agreement between computed and experimental results is sufficient if one takes into account the experimental errors and the nucleus binding energy

  5. Exclusive study of the formation and the decay of hot nuclei in the intermediate energy domain

    International Nuclear Information System (INIS)

    Saint-Laurent, F.

    1990-01-01

    A brief review of exclusive measurements performed at GANIL in order to study hot nuclei will be given. Heavy-ion induced reactions on heavy targets have been investigated over a wide range of incident energy, using various techniques: - fission fragment angular correlations. - 4 π neutron multiplicity measurements. - light charged particle correlations. In each case, a selection of the most violent collisions can be achieved. For central collisions induced by 40 Ar, a same excitation energy of about 650 MeV is deduced from the totally different and independent sets of data, corresponding to an average temperature of 5 MeV. At 60 MeV/u, this value is quite low as compare to the total available energy for central collisions A tentative explanation based on Landau-Vlasov simulations will be proposed: the excitation energy dissipated in the system could be stored in a highly excited compression mode as well as under a thermal form. Some recent results on the Kr+Au system at 32 MeV/u will be presented indicating that heavier projectiles than 40 Ar can lead to a temperature of the hot system approaching 7 MeV

  6. Production and desexcitation of hot nuclei in 40Ar + 238U collisions at 27 MeV/u

    International Nuclear Information System (INIS)

    Jacquet, D.

    1987-01-01

    The selection of hot nuclei can be achieved through the folding angle of the coincident fission fragments. At this bombarding energy a distinct fusion component shows up in the folding angle correlation function corresponding to the most central collisions. The mass of the fission fragments decreases with increasing linear momentum transfer; the energy dissipated into the target nucleus is proportional to the momentum transfer. The mass distribution full width at half maximum increases with dissipated energy and this can be understood as the result of thermal fluctuations. The light charged particles detected in coincidence with the fission fragments exhibit, at least backwards, the characteristic behaviour of evaporative particles from a thermally equilibrated source. The fused nucleus is revealed as the dominant emitter. The observed energy spectra can be reproduced in a Monte Carlo type simulation assuming that about 80% of the particles arise from the fused nuclei and only 20 % from the fully accelerated fission fragments. A detailed analysis of the shape of the spectra allows to precise the average characteristics of the emitter: it is quite deformed has a very broad spin distribution and a temperature from 4 to 5 MeV. All these characteristics are consistently deduced in semi-classical dynamical calculations based on the Landau-Vlasov equation. The pre-fission particle emission probabilities are shown to be much larger than would predict a purely statistical model for such heavy and hot nuclei. Such a behaviour can only be understood if the dynamics of the collision is taken into account [fr

  7. Target fragmentation in deep inelastic scattering of 14.5 GeV electrons from nuclei

    International Nuclear Information System (INIS)

    Degtyarenko, P.; Gavrilov, V.; Shuvalov, S.

    1993-01-01

    Results will be presented for inclusive pion, kaon, proton and deuteron electroproduction from light nuclei (mainly 12 C and 16 O) of the residual gas in the beam pipe of the TPC/2γ detector at SLAC. Counter-circulating beams of 14.5 GeV electrons and positrons were used. Comparison will be made with the fragmentation of 2 H, 40 Ar, and Xe target nuclei in several regions of Q 2 and ν. The dependence of the hadron production on the hadron's kinetic energy, emission angle, and x f will be presented. The results will be compared with models of nuclear fragmentation

  8. Fragmentation induced in nuclei by protons and pions

    International Nuclear Information System (INIS)

    Cassagnou, Y.; Dalmas, J.; Jackson, H.E.; Julien, J.; Palmeri, A.; Legrain, R.; Roussel, L.

    1977-01-01

    Data from in-beam γ spectroscopy and from detection of charged particles in p-nucleus and π-nucleus interaction at intermediate energies are reviewed. Preliminary data from coincidence experiments are presented showing the apparent weak component of fragmentation in p-nucleus interaction and the primary role of absorption in π-nucleus interaction. In these experiments the energy spectra of emitted particles were found strongly dependent on exit channels giving a powerful tool to test reaction mechanism models [fr

  9. Characteristics of spectators in 4He nuclei fragmentation processes

    International Nuclear Information System (INIS)

    Bano, M.; Braun, H.; Futo, A.

    1984-10-01

    Characteristics were studieO of deuteron, 3 H and 3 He spectators emitted in 4 He-p interactions at 8.6 GeV/c incident momentum. A model using the Monte Carlo procedure is proposed which predicts the momentum distribution for a nucleon or a group of nucleons (d, 3 H, 3 He) in the 4 He nucleus and describes some properties of reaction channels with spectator emission. The predictions are compared with experimental data. Good agreement is obtained taking into account the influence of the experimental errors and of the binding energy between the fragments. (author)

  10. Langevin description of fission fragment charge distribution from excited nuclei

    CERN Document Server

    Karpov, A V

    2002-01-01

    A stochastic approach to fission dynamics based on a set of three-dimensional Langevin equations was applied to calculate fission-fragment charge distribution of compound nucleus sup 2 sup 3 sup 6 U. The following collective coordinates have been chosen - elongation coordinate, neck-thickness coordinate, and charge-asymmetry coordinate. The friction coefficient of charge mode has been calculated in the framework of one-body and two-body dissipation mechanisms. Analysis of the results has shown that Langevin approach is appropriate for investigation of isobaric distribution. Moreover, the dependences of the variance of the charge distribution on excitation energy and on the two-body viscosity coefficient has been studied

  11. The giant resonance and the shape of hot nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Bracco, A; Camera, F; Million, B; Pignanelli, M [Milan Univ. (Italy). Ist. di Fisica; Gaardhoje, J J; Maj, A; Atac, A [Niels Bohr Inst., Copenhagen (Denmark)

    1992-08-01

    The gamma decay of the giant dipole resonance is a sensitive tool for investigating how nuclear shape changes with spin and excitation energy, but the information is coded in a subtle way, inasmuch as the shape and orientation of nuclei at finite temperature display large fluctuations. At the time of the conference, the three systems {sup 109-110}Sn, {sup 161-162}Yb and {sup 165-167}Er had recently been studied on the HECTOR spectrometer. The Sn nuclei are spherical in their ground states, and are expected to become oblate under the stress of rotation. The Yb and Er nuclei are prolate, and are expected to become first spherical, then oblate. While the patterns of the measured angular anisotropies are consistent with this general picture, many questions still remain open. 3 refs., 1 tab., 3 figs.

  12. The mass (charge) spectrum of superheavy nuclei fission fragments: the new perspectives for the theory of nucleosynthesis

    International Nuclear Information System (INIS)

    Maslyuk, V.T.

    2012-01-01

    A new approach to the problem of nucleosynthesis based on assumption of a nuclear matter or superheavy nuclei series fragmentation up to atomic nuclei is proposed. It is shown that studies of the mass (charge) fragments yields (MCFY) after nuclear matter disintegration is possible within proposed statistical theory. The data of MCFY calculation for exotic superheavy nuclei multifragmentation with A=300, 900 and 1200 and arbitrary Z values are demonstrated

  13. Evidence for different fission behavior of hot nuclei formed in central and peripheral collisions of 40Ar + 209Bi reaction at 25 MeV/u

    International Nuclear Information System (INIS)

    Wu Enjiu; Zheng Jiwen; Xiao Zhigang; Zhang Chun; Tan Jilian; Yin Shuzhi; Wang Sufang; Jin Genming; Yin Xu; Song Mingtao; Jin Weiyang; Peng Xingping; Li Zuyu; Wu Heyu; He Zhiyong; Jiang Dongxing; Qian Xing

    1999-01-01

    Correlated fission fragments from the reaction of 25 MeV/u 40 Ar + 209 Bi and their further correlation with α particles have been studied for peripheral and central collisions simultaneously. The excitation energy at scission deduced from post scission multiplicity is about 172.5 MeV. The fission timescale deduced from prescission multiplicity is about 4 x 10 -21 s. Systematic analysis of the mass and energy distributions of fission fragments as a function of the initial temperature of hot fissioning nuclei reveals the existence of different fission behavior of hot nuclei formed in central and peripheral collisions. Experimental data demonstrate the change of fission behavior at T∼4 MeV

  14. Liquid-fog and liquid-gas phase transitions in hot nuclei

    International Nuclear Information System (INIS)

    Karnaukhov, V.A.; ); Oeschier, H.; Budzanowski, A.

    2006-01-01

    Thermal multifragmentation of hot nuclei is interpreted as the nuclear liquid-fog phase transition inside the spinodal region. The exclusive data for p(8.1 GeV) + Au collisions are analyzed within the framework of statistical model (SSM). It is found that the partition hot nuclei is specified after expansion to a volume equal to V t = (2.6 ± 0.3)V 0 . The freeze-out volume is found to be twice as large V f = (5 ± 1)V 0 . The similarity between multifragmentation and ordinary fission is discussed [ru

  15. Using nuclear structure to study the vaporization of hot nuclei

    International Nuclear Information System (INIS)

    Broglia, R.A.

    1985-01-01

    Many experiments on the gamma decay of highly excited nuclei show the persistence of the giant dipole resonance as a collective mode even under rather extreme conditions. The theory of these resonances predicts that they should essentially retain the properties they have in the ground state to quite high excitation. The average resonance energy may be studied in mean-field theory and is found to change less than 5% for temperatures as high as approx.1.5 MeV. The spreading of the resonance has recently been calculated for nuclei at finite temperatures and rotational frequencies. The damping is found to increase by an insignificant amount in the measured temperature range, except when the nucleus changes deformation. The authors argue here that the stability of the dipole may be used to advantage in the study of other properties of nuclei at high excitation. For example, given that a compound nucleus is formed in a heavy-ion reaction, the dipole branching ratio is very sensitive to the statistical properties of the nucleus. The branching ratio allows a more sensitive measurement of the level density parameter at high excitation than would be otherwise available

  16. SYMMETRICAL AND ASYMMETRIC TERNARY FISSION OF HOT NUCLEI

    NARCIS (Netherlands)

    SIWEKWILCZYNSKA, K; WILCZYNSKI, J; LEEGTE, HKW; SIEMSSEN, RH; WILSCHUT, HW; GROTOWSKI, K; PANASIEWICZ, A; SOSIN, Z; WIELOCH, A

    Emission of a particles accompanying fusion-fission processes in the Ar-40 + Th-232 reaction at E(Ar-40) = 365 MeV was studied in a wide range of in-fission-plane and out-of-plane angles. The exact determination of the emission angles of both fission fragments combined with the time-of-flight

  17. Evidence for anomalous nuclei among relativistic projectile fragments at Bevalac energies

    International Nuclear Information System (INIS)

    Heckman, H.H.

    1981-01-01

    Two independent emulsion experiments using beams of 16 O and 56 Fe at approximately 2 GeV/nucleon find that the reaction mean free paths of projectile fragments (PF) with Z between 3 and 26 are shorter for a few centimeters after their emission than at larger distances, or than predicted from experiments on beam nuclei. Under the assumption that there are two populations of PF, a best fit to the data is obtained when approximately 6% of the PF have an anomalously short mean free path. The anomalous property of PF persists in subsequent fragmentation reactions. 6 figures

  18. Mechanism of f-decay - spontaneous emission of fragments by heavy nuclei

    International Nuclear Information System (INIS)

    Rubchenya, V.A.; Ehjsmont, V.P.; Yavshits, S.G.

    1987-01-01

    A new type of model of radioactive decay - spontaneous emission of fragments by heavy nuclei, for which f-decay has been suggested, is formulated. The consideration is based on representation about a disintegrating configuration, for which the probability of f-cluster formation is close to 1. The moments method is used to determine the parameters of the disintegrating configuration. The probability of disintegrating configuration formation is determined by collective properties of a disintegrating nucleus. Effect of nucleon shells of the daughter nucleus and fragment leads to more compact disintegrating configuration and to decay energy increase, that's why at f-decay magic nuclei are formed. Probable spontaneous f-decay values calculated agree satisfactorily with experimental data. The calculational results testify to considerable decrease of f-decay probability at Z≥94

  19. Effects of fissioning nuclei distributions on fragment mass distributions for high energy fission

    Directory of Open Access Journals (Sweden)

    Rossi P C R

    2012-02-01

    Full Text Available We study the effects of fissioning nuclei mass- and energy-distributions on the formation of fragments for fission induced by high energy probes. A Monte Carlo code called CRISP was used for obtaining mass distributions and spectra of the fissioning nuclei for reactions induced by 660 MeV protons on 241Am and on 239Np, by 500 MeV protons on 208Pb, and by Bremsstrahlung photons with end-point energies at 50 MeV and 3500 MeV on 238U. The results show that even at high excitation energies, asymmetric fission may still contribute significantly to the fission cross section of actinide nuclei, while it is the dominante mode in the case of lead. However, more precise data for high energy fission on actinide are necessary in order to allow definite conclusions.

  20. Entrance channel influence on the formation and decay of hot nuclei

    International Nuclear Information System (INIS)

    Harar, S.

    1987-04-01

    Different entrance channels have been investigated to form very hot nuclei and to study their decay properties. i) Argon and Nickel projectiles accelerated around the Fermi energy show that central collisions induce momentum transfers to target nuclei which are proportional to the mass of the projectile and not to its velocities in the studied energy range. The preequilibrium model fits nicely the experimental results. The decay properties of the fission products for hot nuclei will be presented. Both head-on collisions and peripheral massive transfers contribute to the formation of very excited nuclei. The question of the influence of the energy deposit in the composite like system in limiting their yields is discussed. ii) Investigations have been also achieved with alpha projectiles at much higher incident energy (around 1 GeV/u). It is shown that hot and thermalized nuclei are also formed even when the nucleon-nucleon collisions are predominant. A sensitive parameter of the transition from binary fission to multifragmentation seems to be the energy deposit in the target residues rather than the projectile velocity

  1. Influence of fragment deformation and orientation on compact configuration of odd-Z superheavy nuclei

    International Nuclear Information System (INIS)

    Gurjit Kaur; Sandhu, Kirandeep; Sharma, Manoj K.

    2016-01-01

    The synthesis of heavy and superheavy nuclei is generally carried out by using hot and cold fusion reaction mechanisms. It has been noticed that, the cold fusion reactions occur at relatively low excitation energies (E*_C_N ∼ 10-20 MeV) whereas, the hot fusion reactions occur at excitation energies of E*_C_N ∼ 30- 50 MeV. The fusion mechanism is quite different in both the processes. In the cold fusion process, the interaction of spherical targets (Pb and Bi) with deformed light mass projectiles occurs. On the other hand, the fusion of deformed actinide targets with spherical "4"8Ca projectile characterize the hot interaction processes. Hence the deformations and orientations of targets and projectiles play extremely important role in the superheavy fusion process. The present analysis is carried out to aggrandize the work of which illustrate the role of deformations and orientations on even superheavy nuclei. Here, we extend this analysis for odd superheavy nuclei. It is relevant to note that the temperature and angular momentum effects are not included in the present analysis

  2. Excitation of giant modes and decay of hot nuclei

    International Nuclear Information System (INIS)

    Chomaz, Ph.

    1992-01-01

    Several phenomena are discussed which can affect the properties of the Giant Dipole Resonance (GDR) built on excited states. The effect of the N over Z ratio is proposed in the entrance channel to test the hypothesis that the saturation of the GDR strength is due to preequilibrium effects. The important role of the compression is discussed both for the calculation of the temperature and for the other parameters of the Hot GDR. (K.A.) 15 refs.; 9 figs

  3. Liquid-gas phase transition in hot nuclei: correlation between dynamical and thermodynamical signals

    Energy Technology Data Exchange (ETDEWEB)

    Rivet, M.F.; Borderie, B.; Desesquelles, P.; Galichet, E. [Institut de Physique Nucleaire, IN2P3-CNRS, 91 - Orsay (France); Bougault, R.; Le Neindre, N. [Caen Univ, LPC, IN2P3-CNRS, ISMRA, 14 - Caen (France); Galichet, E. [Conservatoire National des Arts et Metiers, 75 - Paris (France); Guiot, B.; Wieleczko, J.P. [GANIL, CEA et IN2P3-CNRS, 14 - Caen (France); Parlog, M.; Tabacaru, G. [Nat. Inst. for Physics and Nuclear Engineering, Bucharest-Magurele (Romania)

    2003-07-01

    The dynamics and thermodynamics of phase transition in hot nuclei are studied through experimental results on multifragmentation of heavy systems (A(projectile) + A(target) > 200) formed in central heavy ion collisions. Different signals such as negative heat capacity and spinodal decomposition, indicative of a phase transition studied in the INDRA collaboration are presented and their consistency is stressed. (authors)

  4. The decay of hot nuclei formed in La-induced reactions at E/A=45 MeV

    International Nuclear Information System (INIS)

    Libby, B.

    1993-01-01

    The decay of hot nuclei formed in the reactions 139 La + 27 Al, 51 V, nat Cu, and 139 La were studied by the coincident detection of up to four complex fragments (Z > 3) emitted in these reactions. Fragments were characterized as to their atomic number, energy and in- and out-of-plane angles. The probability of the decay by an event of a given complex fragment multiplicity as a function of excitation energy per nucleon of the source is nearly independent of the system studied. Additionally, there is no large increase in the proportion of multiple fragment events as the excitation energy of the source increases past 5 MeV/nucleon. This is at odds with many prompt multifragmentation models of nuclear decay. The reactions 139 La + 27 Al, 51 V, nat Cu were also studied by combining a dynamical model calculation that simulates the early stages of nuclear reactions with a statistical model calculation for the latter stages of the reactions. For the reaction 139 La + 27 Al, these calculations reproduced many of the experimental features, but other features were not reproduced. For the reaction 139 La + 51 V, the calculation failed to reproduce somewhat more of the experimental features. The calculation failed to reproduce any of the experimental features of the reaction 139 La + nat Cu, with the exception of the source velocity distributions

  5. Experimental studies of the formation and decay of hot nuclei

    International Nuclear Information System (INIS)

    Nifenecker, H.; Blachot, J.; Crancon, J.; Gizon, A.; Lleres, A.

    1985-06-01

    In the following we shall report on a number of measurements made with different projectiles ranging from 12 C to 40 Ar. In most cases the target was 124 Sn. In this case the reported results were obtained by off line γ counting of series of catchers allowing mass and velocity measurements of the quasi compound or quasi target recoils 11 . We shall also refer to some other results using conventional counter techniques and either lightersup(12,13) or heavier targetssup(14,15,16). We shall first examine the cross section for quasi fusion. We shall then adress the question of the limit of momentum transfer and that of the inference of excitation energies from recoil energies. Finally we discuss the possible observation of a threshold in the excitation energy that nuclei can support without breaking apart

  6. Hot nuclei studied with high efficiency neutron detectors

    International Nuclear Information System (INIS)

    Galin, J.

    1990-01-01

    We have shown the invaluable benefit that a high efficiency 4π neutron detector can bring to the study of reaction mechanisms following collisions of heavy nuclei at intermediate energy. Analysis requires Monte-Carlo simulations for comparison between experimental data and any emission model. In systematic measurements with projectiles of velocity corresponding to energies between 27 and 77 MeV/u, where both the influence of beam velocity and mass have been investigated separately, it has been shown that the projectile-target mass asymmetry, much more than velocity, has a decisive influence on energy dissipation. The closer the projectile mass to the target mass, the more energy is dissipated per unit mass of the considered projectile plus target system. The latter presents all the characteristics of a thermalized system, evaporating a copious number of light particles: up to about 40 neutrons (after efficiency correction) and 11 light charged particles in the most dissipative collisions between Kr+Au, and 90 neutrons for Pb+U with a yet unknown number of l.c.p. In the Kr experiment, these particles are isotropically emitted in the frame of a fused system, excited with 1.2 GeV. Moreover, l.c.p. exhibit Maxwellian energy distributions as in any standard evaporation process. We are now eager to better characterize the properties of the Pb+Au (U) systems for which about 1/3 of the neutrons are freed in a rather large fraction of all collisions. The thermalized energy should then approach very closely the total binding energy of the two interacting nuclei

  7. Effect of deformations on the compactness of odd-Z superheavy nuclei formed in cold and hot fusion reactions

    Science.gov (United States)

    Kaur, Gurjit; Sandhu, Kirandeep; Sharma, Manoj K.

    2018-03-01

    Using the extended fragmentation theory, the compactness of hot and cold fusion reactions is analyzed for odd-Z nuclei ranging Z = 105- 117. The calculations for the present work are carried out at T = 0MeV and ℓ = 0 ħ, as the temperature and angular momentum effects remain silent while addressing the orientation degree of freedom (i.e. compact angle configuration). In the hot fusion, 48Ca (spherical) + actinide (prolate) reaction, the non-equatorial compact (nec) shape is obtained for Z = 113 nucleus. On the other hand, Z > 113 nuclei favor equatorial compact (ec) configuration. The distribution of barrier height (VB) illustrate that the ec-shape is obtained when the magnitude of quadrupole deformation of the nucleus is higher than the hexadecupole deformation. In other words, negligible or small -ve β4-deformations support ec configurations. On the other hand, large (+ve) magnitude of the β4-deformation suggests that the configuration appears for compact angle θc < 90 °, leading to nec structure. Similar deformation effects are observed for Bi-induced reactions, in which not belly-to-belly compact (nbbc) configurations are seen at θc = 42 °. In addition to the effect of β2 and β4-deformations, the exclusive role of octupole deformations (β3) is also analyzed. The β3-deformations do not follow the reflection symmetry as that of β2 and β4, leading to the possible occurrence of compact configuration within 0° to 180° angular range.

  8. Fragmentation of stretched spin strength in N=Z sd-shell nuclei

    International Nuclear Information System (INIS)

    Carr, J.A.; Bloom, S.D.; Petrovich, F.; Philpott, R.J.

    1992-01-01

    Calculations have been performed to explore the effect of configuration mixing in a large basis on the fragmentation of ''stretched'' M6 strength in the sd-shell nuclei 20 Ne, 24 Mg, 28 Si, 32 S, and 36 Ar. This work elaborates on results for 28 Si given previously, extends those calculations to neighboring N=Z nuclei with the same basis restriction (one particle in the 1f 7/2 orbit and up to four particles in the 1d 3/2 orbit) used in that earlier paper, and examines all self-conjugate sd-shell nuclei in a basis with one particle in the 1f 7/2 orbit and unrestricted occupancy of the sd-shell orbits. It is found that configuration mixing in a large basis reproduces interesting features of the spectrum for 28 Si and 32 S and gives an improved description of other properties of the observed 6 - states, but fails to describe the observed spectrum in 24 Mg. Emphasis is placed on the location of additional observable fragments of the M6 response

  9. New approach to the nuclear in beam γ spectroscopy of neutron rich nuclei at N=20 using projectile fragmentation

    International Nuclear Information System (INIS)

    Lopez-Jimenez, M.J.; Saint-Laurent, M.G.; Achouri, L.; Daugas, J.M.; Belleguic, M.; Azaiez, F.; Bourgeois, C.; Angelique, J.C.

    1999-01-01

    The structure of nuclei far from stability around 32 Mg have been recently investigated by means of a novel method. In-beam γ-decay spectroscopy of a large number of exotic neutron-rich nuclei produced by projectile fragmentation of a 36 S projectile has been performed, using coincidences between the recoil fragments collected at the focal plane of SPEG spectrometer and γ-rays emitted at the target location. Preliminary results on both the population mechanism and the decay of excited states in nuclei around 32 Mg are presented. (author)

  10. Theory of hot and rotating nuclei within the static path approximation

    International Nuclear Information System (INIS)

    Ansari, A.

    1995-01-01

    For the description of hot and rotating nuclei the static path approximation to the path integral representation of the partition function is at present the best practicable approach incorporating rigorously the statistical fluctuations in nuclear shape degrees of freedom. The paper briefly discusses the method and present a few of the recent results on level densities and GDR (giant dipole resonance) γ-absorption cross sections. (author). 22 refs., 2 figs

  11. Formation of fission-fragment mass distribution for nuclei lighter than thorium

    International Nuclear Information System (INIS)

    Itkis, M.G.; Mul'gin, S.I.; Rusanov, A.Y.; Okolovich, A.N.; Smirenkin, G.N.

    1986-01-01

    A phenomenological approach to description of fission-fragment mass distribution Y(M) for nuclei in the vicinity of Pb is developed and used to extract from the experimental Y(M) data the nuclear deformation potential energy V(M) and its components: the macroscopic (liquid-drop) part and the shell correction in the transition state. The results of the analysis are compared with the theoretically obtained V(M) and Y(M). The three-hump fragment-mass distributions observed in Ra fission are satisfactorily described within the framework of the approach developed. The properties of the symmetric and asymmetric fission valleys and the related Y(M) components are discussed

  12. Lessons from hot spot analysis for fragment-based drug discovery

    Science.gov (United States)

    Hall, David R.; Vajda, Sandor

    2015-01-01

    Analysis of binding energy hot spots at protein surfaces can provide crucial insights into the prospects for successful application of fragment-based drug discovery (FBDD), and whether a fragment hit can be advanced into a high affinity, druglike ligand. The key factor is the strength of the top ranking hot spot, and how well a given fragment complements it. We show that published data are sufficient to provide a sophisticated and quantitative understanding of how hot spots derive from protein three-dimensional structure, and how their strength, number and spatial arrangement govern the potential for a surface site to bind to fragment-sized and larger ligands. This improved understanding provides important guidance for the effective application of FBDD in drug discovery. PMID:26538314

  13. Lessons from Hot Spot Analysis for Fragment-Based Drug Discovery.

    Science.gov (United States)

    Hall, David R; Kozakov, Dima; Whitty, Adrian; Vajda, Sandor

    2015-11-01

    Analysis of binding energy hot spots at protein surfaces can provide crucial insights into the prospects for successful application of fragment-based drug discovery (FBDD), and whether a fragment hit can be advanced into a high-affinity, drug-like ligand. The key factor is the strength of the top ranking hot spot, and how well a given fragment complements it. We show that published data are sufficient to provide a sophisticated and quantitative understanding of how hot spots derive from a protein 3D structure, and how their strength, number, and spatial arrangement govern the potential for a surface site to bind to fragment-sized and larger ligands. This improved understanding provides important guidance for the effective application of FBDD in drug discovery. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. MCNP6 Simulation of Light and Medium Nuclei Fragmentation at Intermediate Energies

    Energy Technology Data Exchange (ETDEWEB)

    Mashnik, Stepan Georgievich [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Kerby, Leslie Marie [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-05-22

    MCNP6, the latest and most advanced LANL Monte Carlo transport code, representing a merger of MCNP5 and MCNPX, is actually much more than the sum of those two computer codes; MCNP6 is available to the public via RSICC at Oak Ridge, TN, USA. In the present work, MCNP6 was validated and verified (V&V) against different experimental data on intermediate-energy fragmentation reactions, and results by several other codes, using mainly the latest modifications of the Cascade-Exciton Model (CEM) and of the Los Alamos version of the Quark-Gluon String Model (LAQGSM) event generators CEM03.03 and LAQGSM03.03. It was found that MCNP6 using CEM03.03 and LAQGSM03.03 describes well fragmentation reactions induced on light and medium target nuclei by protons and light nuclei of energies around 1 GeV/nucleon and below, and can serve as a reliable simulation tool for different applications, like cosmic-ray-induced single event upsets (SEU’s), radiation protection, and cancer therapy with proton and ion beams, to name just a few. Future improvements of the predicting capabilities of MCNP6 for such reactions are possible, and are discussed in this work.

  15. Pion production and fragmentation of nuclei in high energy nucleus-nucleus collisions

    International Nuclear Information System (INIS)

    Oskarsson, A.

    1983-01-01

    In collisions between nuclei at high energies one can study the behaviour of nuclear matter under extreme conditions, regarding nuclear density and temperature. The Bevalac and the CERN SC beams have been used and nuclear emulsion and scintillation telescopes have measured the reaction products. Collisions at 50A-200A MeV and at 2A GeV have been investigated. Proton spectra from 12 C induced reactions at 85A MeV have been recorded for different targets. Energetic protons at large angles can be assumed to be emitted from a source moving with half the beam velocity and a temperature between 13 and 17 MeV, depending on the target. In collisions between nuclei, pions can be produced below 290A MeV due to the internal Fermi motion of the nucleons. Subthreshold pion production has been studied for 12 C induced reactions at 85A and 75A Mev. The cross-sections are consistent with a quasi-free nucleon-nucleon scattering picture, involving Fermi motion, Pauli blocking and pion reabsorption. 16 C induced reactions in emulsion have been studied at 75A, 175A and 2000A MeV. It is shown that the excitation of the parts of the nuclei which are not overlapping (the spectators) increases with the beam energy. The 16 O projectile frequently breaks up into multiple He fragments. These events are associated with large impact parameters. Central collisions with Ag, Br target at 50A-110A MeV have been analysed separately. It is shown that the momentum transfer to the target nucleus is limited to a value considerably lower than the full momentum transfer in a fusion reactions. Events are observed where there are numerous fragments with 3< Z<8. These multifragmentation events cannot be understood in a thermal approach. (author)

  16. I. The properties of hot Ca-like fragments from the 40Ca+40Ca reaction at 35 AMeV

    International Nuclear Information System (INIS)

    Planeta, R.; Gawlikowicz, W.; Wieloch, A.

    2001-01-01

    The creation of hot Ca-like fragments was investigated in the 40 Ca + 40 Ca reaction at 35 AMeV. Using the AMPHORA 4π detector system, the primary projectile-like fragment was reconstructed and its properties were determined. Both primary and secondary distributions are compared with the predictions of a Monte Carlo code describing a heavy-ion collision as a two-step process. Some of the nucleons which are identified as participants in the first step are transferred in the second step to these final states, which correspond on the average to the maximum value of entropy (thermodynamic probability). The model allows for competition between mean-field effects and nucleon-nucleon interactions in the overlap zone of the interacting nuclei. The analysis presented here suggests a thermalized source picture of the decay of the projectile-like fragment. The validity of the reconstruction procedure for projectile-like fragments is discussed. (orig.)

  17. Fission of heavy nuclei: microscopic study of fission barriers and fragments angular momentum

    International Nuclear Information System (INIS)

    Bonneau, L.

    2003-11-01

    A lot of experimental data on nuclear fission has been being collected for the last 65 years, allowing theoreticians to confront their models with reality. The first part of this work is dedicated to the computation of fission barriers. We have extended the HF + BCS (Hartree Fock + Bandeen-Cooper-Schrieffer) method in order to include a new set of polynomials on which wave functions can be broken to, more accurately than on Hermite's polynomials in the 2 fragment configuration. The fission barriers of 26 heavy nuclei from Thorium-230 to Nobelium-256 have been assessed and compared to experimental data, it appears that differences are no greater than 1 MeV. We have discovered a neat correlation between the variation of the experimental fission lifetimes of even Fermium isotopes and the computed heights of second barriers. Moreover our model reproduces the hyper-deformed well of Thorium-230 with a good agreement on the well depth. The second part deals with the scission region. We have performed Hartree-Fock calculations in order to explore different ways of fragmentation. We have shown that the harmonic oscillator gives a valid description of such ways. In order to compute the mean value of J 2 in the fragments we have been driven to propose an adequate definition of that quantity consistent with the non-locality property of the J 2 operator. (A.C.)

  18. The key point of fragmentation of quasiparticle-phonon configurations in the order-disorder transformations of atomic nuclei

    International Nuclear Information System (INIS)

    Solov'ev, V.G.

    1993-01-01

    To find out at what excitation energies the order-disorder transformations occur in intermediate and heavy nuclei, it is suggested to study fragmentation of multiquasiparticle and quasiparticle-phonon configurations. One-nucleon transfer reactions on odd-odd targets, for instance on 176 Lu and 180 Ta, should be taken as a particular case of fragmentation of three-quasiparticle configurations on the long living isomer 178 m 2 Hf-fragmentation of five-quasiparticle configurations. From the analysis of γ-decay of high-spin isomers one can information on fragmentation of quasi-phonon configurations

  19. Fission and nuclear fragmentation of silver and bromine nuclei by photons of 1-6 GeV

    International Nuclear Information System (INIS)

    Pinheiro Filho, J.D.

    1983-01-01

    The studies of fission and fragmentation of silver and bromine nuclei by Bremsstrahlung photons of 1.6 GeV energy range are presented. The Il ford-KO nuclear emulsion submitted to Bremsstrahlung beams in Deutsches Elektronen Synchrotron (DESY) with total doses of 10'' equivalent photons, was used for nuclear fragment detection. The discrimination of fission and fragmentation events was done analysing angular distribution, range and angles between fragments. The results of fragment range distributions, angular distributions, distributions of angles between fragments, distributions of ratio between range, velocity distributions forward/backward ratio, cross sections of fission and fragmentation, nuclear fissionability and ternary fission frequency are presented and discussed. (M.C.K.)

  20. Is the caloric curve a robust signal of the phase transition in hot nuclei?

    International Nuclear Information System (INIS)

    Vient, E.

    2016-01-01

    The richness of the data set, collected by the INDRA Collaboration during the last twenty years, enabled to build a set of caloric curves for nuclei of various sizes, by using, for the first time, a single experimental set-up and a single experimental protocol. We will therefore present the different caloric curves (E ∗ −T) obtained by a new calorimetry, for Quasi-Projectiles produced by symmetric or quasi symmetric reactions at different incident energies (Au+Au, Xe+Sn, Ni+Ni). For all these systems, a clear change of the de-excitation process of hot nuclei is observed but this one is neither a plateau nor a back-bending, but a sudden change of slope.

  1. Langevin description of mass distributions of fragments originating from the fission of excited nuclei

    International Nuclear Information System (INIS)

    Vanin, D.V.; Nadtochy, P.N.; Adeev, G.D.; Kosenko, G.I.

    2000-01-01

    A stochastic approach to fission dynamics is proposed. The approach, which is based on Langevin equations, is used to calculate the mass distributions of fragments originating from the fission of excited nuclei. The effect of viscosity and light-particle emission on the variance of mass distributions is studied. The results of the calculations based on the above approach reveal that, in order to obtain a simultaneous description of mass-distribution parameters and the multiplicities of prescission particles, it is necessary to use sufficiently large values of nuclear viscosity both for the one-body and for the two-body viscosity mechanism, anomalously large values of the viscosity coefficient being required in the latter case

  2. Hot-stage microscopy for determination of API fragmentation: comparison with other methods.

    Science.gov (United States)

    Šimek, Michal; Grünwaldová, Veronika; Kratochvíl, Bohumil

    2016-08-01

    Although the fragmentation of the active pharmaceutical ingredient (API) is a phenomenon that is mentioned in many literature sources, no well-suited analytical tools for its investigation are currently known. We used the hot-stage microscopy method, already presented in our previous work, and studied the real fragmentation of the tadalafil particles in model tablets which were prepared under different compaction pressures. The morphology, spectral imaging and evaluation of plastic and elastic energies were also analyzed to support the hot-stage method. The prepared blend of tadalafil and excipients was compacted under a several forces from 5 to 35 kN to reveal the trend of fragmentation. The exact fragmentation of tadalafil with increased compaction pressure was revealed by the hot-stage microscopic method and it was in good agreement with plastic and elastic energies. Conversely, spectral imaging, which is being used for this analysis, was considered to be inaccurate methodology as mainly agglomerates, not individual particles, were measured. The availability of the hot-stage microscopic method equips pharmaceutical scientists with an in vitro assessment technique that will more reliably determine the fragmentation of the API in finished tablets and the behavior of the particles when compacted.

  3. Thermal multifragmentation of hot nuclei and liquid-fog phase transition

    International Nuclear Information System (INIS)

    Karnaukhov, V.A.; Avdeev, S.P.; Duginova, E.V.

    2002-01-01

    Multiple emission of intermediate-mass fragments in the collisions of protons (up to 8.1 GeV), 4 He(4 and 14.6GeV) and 12 C(22.4 GeV) on Au has been studied with the 4π-setup FASA. In all cases thermal multifragmentation of the hot and diluted target spectator takes place. The fragment multiplicity and charge distributions are well described by the combined model including the modified intranuclear cascade followed by the statistical multibody decay of the hot system. IMF-IMF correlation study supports this picture giving very short time scale of the process (τ≤70fm/c). This decay process can be interpreted as the first order nuclear liquid-fog phase transition inside the spinodal region. The evolution of the mechanism of thermal multifragmentation with increasing projectile mass was investigated. The onset of the radial collective flow was observed for heavier projectiles. The analysis reveals the information on the fragment space distribution inside the break-up volume: heavier IMF are formed predominantly in the interior of the fragmenting nucleus possibly due to the density gradient

  4. The effect of the Pauli principle on the fragmentation of one-quasiparticle states in spherical nuclei

    International Nuclear Information System (INIS)

    Khuong, C.Z.; Soloviev, V.G.; Voronov, V.V.

    1981-01-01

    The effect of the Pauli principle on the fragmentation of one-quasiparticle states in spherical nuclei is studied within the quasiparticle-phonon nuclear model. It is shown that the Pauli principle influences considerably the position and structure of a few low-lying states, the fragmentation of one-quasiparticle states at intermediate and high excitation energies is slightly affected by the Pauli principle, and the calculations can be performed by taking the Pauli principle roughly into account. (author)

  5. Fragmentation of two-phonon {gamma}-vibrational strength in deformed nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Wu, C.Y.; Cline, D. [Univ. of Rochester, NY (United States)

    1996-12-31

    Rotational and vibrational modes of collective motion. are very useful in classifying the low-lying excited states in deformed nuclei. The rotational mode of collective motion is characterized by rotational bands having correlated level energies and strongly-enhanced E2 matrix elements. The lowest intrinsic excitation with I,K{sup {pi}} = 2,2{sup +} in even-even deformed nuclei, typically occurring at {approx}1 MeV, is classified as a one-phonon {gamma}-vibration state. In a pure harmonic vibration limit, the expected two-phonon {gamma}-vibration states with I,K{sup {pi}} = 0,0{sup +} and 4,4{sup +} should have excitation energies at twice that of the I,K{sup {pi}} = 2,2{sup +} excitation, i.e. {approx}2 MeV, which usually is above the pairing gap leading to possible mixing with two-quasiparticle configurations. Therefore, the question of the localization of two-phonon {gamma}-vibration strength has been raised because mixing may lead to fragmentation of the two-phonon strength over a range of excitation energy. For several well-deformed nuclei, an assignment of I,K{sup {pi}}=4,4{sup +} states as being two-phonon vibrational excitations has been suggested based on the excitation energies and the predominant {gamma}-ray decay to the I,K{sup {pi}}=2,2{sup +} state. However, absolute B(E2) values connecting the presumed two- and one-phonon states are the only unambiguous measure of double phonon excitation. Such B(E2) data are available for {sup 156}Gd, {sup 160}Dy, {sup 168}Er, {sup 232}Th, and {sup 186,188,190,192}Os. Except for {sup 160}Dy, the measured B(E2) values range from 2-3 Weisskopf units in {sup 156}Gd to 10-20 Weisskopf units in osmium nuclei; enhancement that is consistent with collective modes of motion.

  6. Formation and de-excitation of very hot nuclei in Ar + Au collisions at 30 and 60 MeV/nucleon

    International Nuclear Information System (INIS)

    Hamdani, T.

    1993-10-01

    The study of the formation and the de-excitation of very hot nuclei by using collisions between Ar and Au at 30 and 60 MeV/u is presented in this work. The detection system consisted of three multidetectors for fragments (DELF) or light particles (TONNEAU+MUR) plus two groups of four detectors (Silicium, CsI). This system and the triggering conditions adopted allowed the selection of two classes of events: semiperipheral collisions and central collisions. The studies presented using global variables, show clearly that the fragments produced in the reactions are emitted from an equilibrated source. Hence, an event generator based on the statistical model was employed to verify the method of calculation of the excitation energy of the source. It also provides information concerning experimental biases and the sensitivity of some of the global variables used in the experimental analysis. A detailed study of the temperatures of hot nuclei is presented using the data recorded with the CsI detectors. The temperatures measured reached up to 7 MeV for the reaction at 60 MeV/u. (orig.)

  7. Thermal Multifragmentation of Hot Nuclei and Liquid-Fog Phase Transition

    CERN Document Server

    Karnaukhov, V A; Duginova, E V; Petrov, L A; Rodionov, V K; Oeschler, H; Budzanowski, A; Karcz, W; Janicki, M; Bochkarev, O V; Kuzmin, E A; Chulkov, L V; Norbeck, E; Botvina, A S

    2002-01-01

    Multiple emission of intermediate-mass fragments in the collisions of protons (up to 8.1 GeV), ^{4}He (4 and 14.6 GeV) and ^{12}C (22.4 GeV) on Au has been studied with the 4\\pi-setup FASA. In all cases thermal multifragmentation of the hot and diluted target spectator takes place. The fragment multiplicity and charge distributions are well described by the combined model including the modified intranuclear cascade followed by the statistical multibody decay of the hot system. IMF-IMF correlation study supports this picture giving very short time scale of the process (\\tau\\le 70 fm/c). This decay process can be interpreted as the first order nuclear liquid-fog phase transition inside the spinodal region. The evolution of the mechanism of thermal multifragmentation with increasing projectile mass was investigated. The onset of the radial collective flow was observed for heavier projectiles. The analysis reveals the information on the fragment space distribution ins! ide the break-up volume: heavier IMF are for...

  8. Hot spot analysis for driving the development of hits into leads in fragment based drug discovery

    Science.gov (United States)

    Hall, David R.; Ngan, Chi Ho; Zerbe, Brandon S.; Kozakov, Dima; Vajda, Sandor

    2011-01-01

    Fragment based drug design (FBDD) starts with finding fragment-sized compounds that are highly ligand efficient and can serve as a core moiety for developing high affinity leads. Although the core-bound structure of a protein facilitates the construction of leads, effective design is far from straightforward. We show that protein mapping, a computational method developed to find binding hot spots and implemented as the FTMap server, provides information that complements the fragment screening results and can drive the evolution of core fragments into larger leads with a minimal loss or, in some cases, even a gain in ligand efficiency. The method places small molecular probes, the size of organic solvents, on a dense grid around the protein, and identifies the hot spots as consensus clusters formed by clusters of several probes. The hot spots are ranked based on the number of probe clusters, which predicts the binding propensity of the subsites and hence their importance for drug design. Accordingly, with a single exception the main hot spot identified by FTMap binds the core compound found by fragment screening. The most useful information is provided by the neighboring secondary hot spots, indicating the regions where the core can be extended to increase its affinity. To quantify this information, we calculate the density of probes from mapping, which describes the binding propensity at each point, and show that the change in the correlation between a ligand position and the probe density upon extending or repositioning the core moiety predicts the expected change in ligand efficiency. PMID:22145575

  9. Fission and fragmentation of silver and bromine nuclei by 1-6 GeV energy photons

    International Nuclear Information System (INIS)

    Pinheiro Filho, J. de D.

    1983-01-01

    Fission and fragmentation of silver and bromine nuclei induced by bremsstrahlung photons in the maximum energy range of 1-6 GeV are studied. A special technique of nuclear emulsion for the highly ionizing nuclear fragment detection is used in the discrimination between nuclear fission and fragmentation events. Films of Ilford-KO nuclear emulsion (approximatelly 10 20 atoms/cm 2 of Ag, Br) which had been exposed to bremsstrahlung beams in 'Deutsches Elektronen Synchrotron' (DESY, Hamburg) with total doses of approximatelly 10 11 equivalent photons are used. Through a detailed analysis of range, angular and angle between fragment distributions, and empirical relations which permit to estimate nuclear fragment energy, range and velocity, the discrimination between fission and fragmentation events is made. Results related to fragment range distribution, angular distribution, distribution of angle between fragments, distribution of ratio between ranges, velocity distributions, forward/backward ratio, fission and fragmentation cross sections, nuclear fissionability and ternary fission frequency are presented and discussed. The results show that the mean photofragmentation cross section in the internal 1-6 GeV (0,09+-0,02mb) is significant when compared to the photofission (0,29+-0,05mb). It is also shown that the mean photofission cross section between 1 and 6 GeV is great by a factor of approximatelly 10 when compared to the foreseen by the cascade-evaporation nuclear model for monoenergetic photons of 0,6 GeV. (L.C.) [pt

  10. Momentum and correlation characteristics of products of fragmentation of relativistic carbon nuclei at 4.5 GeV/c per nucleon

    International Nuclear Information System (INIS)

    Bondarenko, R.A.; Gulamov, K.G.; Gulyamov, U.G.; Chernov, G.M.

    1983-01-01

    We present the basic characteristics (multiplicities, distributions in transverse momenta, and correlations in the transverse plane) of fragments of the incident nucleus in inelastic interactions of relativistic 12 C nuclei in nuclear emulsion. We observe effects of the transverse motion of the fragmenting nucleus and its angular momentum. A qualitative and critical analysis of a number of commonly used theoretical approaches to the fragmentation of relativistic nuclei is given

  11. Damping of isovector giant dipole resonances in hot even-even spherical nuclei

    International Nuclear Information System (INIS)

    Dang, N.D.

    1989-01-01

    An approach based on the finite temperature quasiparticle phonon nuclear model (FT-QPNM) with the couplings to (2p2h) states at finite temperature taken into account is suggested for calculations of the damping of giant multipole resonances in hot even-even spherical nuclei. The strength functions for the isovector giant dipole resonance (IV-GDR) are calculated in 58 Ni and 90 Zr for a range of temperatures up to 3 MeV. The results show that the contribution of the interactions with (2p2h) configurations to the IV-GDR spreading width changes weakly with varying temperature. The IV-GDR centroid energy decreases slightly with increasing temperature. The nonvanishing superfluid pairing gap due to thermal fluctuations is included. (orig.)

  12. Damping width of giant dipole resonances of cold and hot nuclei: A macroscopic model

    International Nuclear Information System (INIS)

    Mughabghab, S.F.; Sonzogni, A.A.

    2002-01-01

    A phenomenological macroscopic model of the giant dipole resonance (GDR) damping width of cold and hot nuclei with ground-state spherical and near-spherical shapes is developed. The model is based on a generalized Fermi liquid model which takes into account the nuclear surface dynamics. The temperature dependence of the GDR damping width is accounted for in terms of surface and volume components. Parameter-free expressions for the damping width and the effective deformation are obtained. The model is validated with GDR measurements of the following nuclides: 39,40 K, 42 Ca, 45 Sc, 59,63 Cu, 109-120 Sn, 147 Eu, 194 Hg, and 208 Pb, and is compared with the predictions of other models

  13. Time-dependent shape fluctuations and the giant dipole resonance in hot nuclei: Realistic calculations

    International Nuclear Information System (INIS)

    Alhassid, Y.; Bush, B.; Yale Univ., New Haven, CT

    1990-01-01

    The effects of time-dependent shape fluctuations on the giant dipole resonance (GDR) in hot rotating nuclei are investigated. Using the framework of the Landau theory of shape transitions we develop a realistic macroscopic stochastic model to describe the quadrupole time-dependent shape fluctuations and their coupling to the dipole degrees of freedom. In the adiabatic limit the theory reduces to a previous adiabatic theory of static fluctuations in which the GDR cross section is calculated by averaging over the equilibrium distribution with the unitary invariant metric. Nonadiabatic effects are investigated in this model and found to cause structural changes in the resonance cross section and motional narrowing. Comparisons with experimental data are made and deviations from the adiabatic calculations can be explained. In these cases it is possible to determine from the data the damping of the quadrupole motion at finite temperature. (orig.)

  14. Probing the degrees of freedom in hot composite nuclei. Systematics of charged particle evaporation

    International Nuclear Information System (INIS)

    Kaplan, M.; Downer, J.B.; Whitfield, J.P.; Brown, C.M.; Milosevich, Z.; Karol, P.J.; Vardaci, E.; Copi, C.; De Young, P.

    1995-01-01

    The study of evaporative particle emission offers a number of experimental observables whose measurement can provide insight into the behavior of highly excited composite nuclei. Simultaneous observations of multiple degrees of freedom in such hot systems allows stringent testing of theoretical models by insisting that the calculations reproduce the several measured characteristics with a single set of model input parameters. Such comparisons are presented for two data sets, one involving a relatively light (low Z) system and the other referring to a relatively heavy (high Z) system. In the latter case, reasonably good agreement has been found between statistical model calculations (with empirical barriers) and the experimental data, while for the former situation, the parameters required to reproduce the energy spectra lead to significant inconsistencies in predicted particle multiplicities and angular anisotropies. (authors). 12 refs., 7 figs., 2 tabs

  15. Dynamical aspects of particle emission in binary dissipative collisions -effects on hot-nuclei formation

    International Nuclear Information System (INIS)

    Eudes, Ph.; Basrak, Z.; Sebille, F.

    1997-01-01

    Characteristics of charged-particle emission in heavy-ion reactions have been studied in the framework of the semiclassical Landau-Vlasov approach for the 40 Ar + 27 Al collisions at 65 MeV/u. The reaction mechanism is dominated by binary dissipative collisions. After an abundant prompt emission coming from the overlapping region between the target and the projectile, two excited nuclei, the quasi-target and the quasi-projectile, emerge from the collision. To shed some light on the role played by dynamical effects, light-charged particle observables, which are currently used as an experimental signature a of hot equilibrated nucleus, have been carefully investigated. (K.A.)

  16. Isovector giant dipole resonance in hot rotating light nuclei in the calcium region

    International Nuclear Information System (INIS)

    Shanmugam, G.; Thiagasundaram, M.

    1989-01-01

    The isovector giant dipole resonances in hot rotating light nuclei in the calcium region are studied using a rotating anisotropic harmonic oscillator potential and a separable dipole-dipole residual interaction. The influence of temperature on the isovector giant dipole resonance is assumed to occur through the change of deformation of the average field only. Calculations are performed for the three nuclei /sup 40,42/Ca and /sup 46/Ti which have spherical, oblate, and prolate ground states, respectively, to see how their shape transitions at higher excited states affect the isovector giant resonance frequencies built on them. It is seen that, while the width fluctuations present at T = 0 vanish at T = 0.5 MeV in /sup 40,42/Ca, they persist up to T = 1.5 MeV in the case of /sup 46/Ti. This behavior brings out the role of temperature on shell effects which in turn affects the isovector giant dipole resonance widths

  17. Fragment emission in reactions of 18.5-GeV 12C ions with complex nuclei

    International Nuclear Information System (INIS)

    Porile, N.T.; Cole, G.D.

    1982-01-01

    The emission of fragments ranging from 24 Na to 52 Mn in reactions of 18.5 GeV 12 C ions with Cu, Ag, Gd, Ta, Au, and U targets has been studied by means of activation techniques. The experiments involved determination of the fragment production cross sections and thick-target recoil properties. The latter were used to obtain mean fragment kinetic energies and values of β/sub parallel to/, the forward velocity component of the struck nucleus (in units of c). The results are compared with similar data for incident protons of the same total kinetic energy. The data may be used to assess the importance of central collisions in fragment production. Such collisions lead to the near total destruction of both interacting nuclei and the resulting fragments are emitted by a system of intermediate rapidity. In such a process, the factorization hypothesis, which has been shown to be valid for target and projectile fragmentation reactions, should not be obeyed. A test for factorization is performed by means of a relation which states that the ratio of the cross sections for producing fragment /sup A/Z in 12 C reactions to that for producing the same fragment in proton reactions with the same target is unity, provided both cross sections are reduced by the values of the corresponding total reaction cross sections sigma/sub R/, and evaluated for the same total kinetic energy of the projectile. The results of this comparison for the targets studied are presented and discussed

  18. The role of compound nuclei and deep-inelastic scattering in complex fragment production at intermediate energies

    International Nuclear Information System (INIS)

    Wozniak, G.J.; Colonna, N.; Charity, R.J.; Moretto, L.G.

    1989-02-01

    The dependence of complex fragment production on the asymmetry of the entrance channel has been investigated with the 18 A MeV 139 La + 12 C, 27 Al, 64 Ni reactions. Invariant cross section plots show a very simple pattern for the two lighter targets and a more complex one for the heavier 64 Ni target. The observed complex fragments are shown to result from quasi-elastic/deep-inelastic reactions and from compound nuclei formed in complete/incomplete fusion processes. 9 refs., 10 figs

  19. Synthesis and decay process of superheavy nuclei with Z=119-122 via hot-fusion reactions

    Energy Technology Data Exchange (ETDEWEB)

    Ghahramany, N.; Ansari, A. [Shiraz University, Department of Physics and Biruni Observatory, College of Science, Shiraz (Iran, Islamic Republic of)

    2016-09-15

    In this research article attempts have been made to calculate the superheavy-nuclei synthesis characteristics including, the potential energy parameters, fusion probability, fusion and evaporation residue (ER) cross sections as well as, decay properties of compound nucleus and the residue nuclei formation probability for elements with Z=119-122 by using the hot-fusion reactions. It is concluded that, although a selection of double magic projectiles such as {sup 48}Ca with high binding energy, simplifies the calculations significantly due to spherical symmetric shape of the projectile, resulting in high evaporation residue cross section, unfortunately, nuclei with Z > 98 do not exist in quantities sufficient for constructing targets for the hot-fusion reactions. Therefore, practically our selection is fusion reactions with titanium projectile because the mass production of target nuclei for experimental purposes is more feasible. Based upon our findings, it is necessary, for new superheavy-nuclei production with Z > 119, to use neutron-rich projectiles and target nuclei. Finally, the maximal evaporation residue cross sections for the synthesis of superheavy elements with Z=119-122 have been calculated and compared with the previously founded ones in the literature. (orig.)

  20. Projectile fragmentation of neutron-rich nuclei on light target (momentum distribution and nucleon-removal cross section)

    International Nuclear Information System (INIS)

    Kobayashi, T.; Tanihata, I.; Suzuki, T.

    1992-01-01

    Transverse momentum distributions of the projectile fragments from β-unstable nuclei have been measured with various projectile and target combinations. The momentum correlation of two neutrons in the neutron halo is extracted from the P c t distribution of 9 Li and hat of the neutrons. It is found that the two neutrons are moving in the same direction on average and thus strongly suggests the formation of a di-neutron in 11 Li. (Author)

  1. Independent Yields of Kr and Xe Fragments at Photofission of Odd Nuclei ^{237}Np and ^{243}Am

    CERN Document Server

    Gangrsky, Yu P; Myshinskii, G V; Penionzhkevich, Yu E

    2004-01-01

    he independent yields of fragments Kr (A=89-93) and Xe (A=135-142) at photofission of odd nuclei 237Np and 243Am are presented. The experiments were performed using the bremsstrahlung of 25 MeV electrons on the microtron of FLNR, JINR. A technique was used that included the transportation of fragments which escaped from the target with the gas flow through a capillary and the condensation of inert gases in a cryostat at the temperature of liquid nitrogen. Kr and Xe isotopes were identified by the spectra of their daughter products. The mass number distributions of the independent yields of Kr and Xe isotopes and of the complementary fragments (Y and La at the photofission of ^{237}Np and Nb and Pr at the photofission of ^{243}Am) were obtained.

  2. Dynamic Failure and Fragmentation of a Hot-Pressed Boron Carbide

    Science.gov (United States)

    Sano, Tomoko; Vargas-Gonzalez, Lionel; LaSalvia, Jerry; Hogan, James David

    2017-12-01

    This study investigates the failure and fragmentation of a hot-pressed boron carbide during high rate impact experiments. Four impact experiments are performed using a composite-backed target configuration at similar velocities, where two of the impact experiments resulted in complete target penetration and two resulted in partial penetration. This paper seeks to evaluate and understand the dynamic behavior of the ceramic that led to either the complete or partial penetration cases, focusing on: (1) surface and internal failure features of fragments using optical, scanning electron, and transmission electron microscopy, and (2) fragment size analysis using state-of-the-art particle-sizing technology that informs about the consequences of failure. Detailed characterization of the mechanical properties and the microstructure is also performed. Results indicate that transgranular fracture was the primary mode of failure in this boron carbide material, and no stress-induced amorphization features were observed. Analysis of the fragment sizes for the partial and completely penetrated experiments revealed a possible correlation between larger fragment sizes and impact performance. The results will add insight into designing improved advanced ceramics for impact protection applications.

  3. Analysis of the fragmentation of hot drops with film boiling in a water flow

    International Nuclear Information System (INIS)

    Malmazet, Erik de

    2009-01-01

    The goal of this work is to study different aspects of the fragmentation of very hot drops placed in a uniform flow, a phenomenon related to vapor explosion studies. First, a theoretical study of the isothermal hydrodynamic fragmentation of drops by the Boundary Layer Stripping (BLS) mechanism is done by developing two models. The first model, contrary to past studies which dismissed the BLS, includes deformation and acceleration effects and this is shown to greatly enhance the mass loss by BLS, which enables this mechanism to become a much more effective mechanism when the external flow is gaseous. But it is still ineffective in the liquid case. The second model describes transient aspects of the BLS, and by coupling it with a stripping criteria for the internal boundary layer, it is possible to predict the time of the initiation of fragmentation. Then, a model for film boiling over horizontal cylinders and axisymmetric bodies which is able to properly describe the inertial and convection terms in the vapor flow is presented. This has never been done before, although these terms cannot be neglected in physical conditions close to vapor explosions. The model is able to predict all the experimental results of TREPAM, the only existing forced convection film boiling experiment in conditions close to a vapor explosion, and which results could not be predicted by other models. In the last part, an experimental study of the fragmentation of hot tin drops in a water flow which uses digital fast camera and flash X ray imagery is presented. This study has allowed the observation of several new features of the drop fragmentation mechanism. (author) [fr

  4. Properties and decay modes of hot nuclei produced in the reaction: 36Ar on 58Ni and detected with INDRA device

    International Nuclear Information System (INIS)

    Nalpas, L.

    1997-01-01

    Hot nuclei are formed in heavy ion collisions covering the Fermi energy domain. According to the excitation energy deposited into these nuclei, several de-excitation processes can be observed, in particular the emission of complex fragments (Z ≥ 3) which remains poorly understood. The GANIL facility offers the possibility to cover the excitation function for the Ar on Ni reaction over a broad energy range from 32 to 95 MeV/u where the hot nuclei evolve from classical 'evaporation' to complete 'vaporization' into light particles (neutrons, isotopes of H, He). The study of reaction mechanisms shows that from peripheral to central collisions the total cross section is dominated by binary dissipative collisions. Both partners coming from well-characterized events with the INDRA detector are reconstructed using the 'Minimum Spanning Tree' method. Thus excitation energy up to 20 MeV/A are reached in the most violent collisions at the highest bombarding energy. The deposited energy is not shared in the mass ratio between the quasi-projectile and the quasi-target, the quasi-projectile being hotter. For total excitation energies ranging roughly from 2 to 8 MeV/A, the proportion of 'multifragmentation' events increases to reach a plateau at about 10 MeV/A due to the rising probability to have complete 'vaporization' of the system above 8 MeV/A. The steady increase of the temperature extracted from the double isotopic He-Li ratios with excitation energy for the quasi-projectile suggests a progressive evolution of the de-excitation processes as predicted by statistical models. No signal of first order liquid-gas phase transition is seen in our data. (author)

  5. Fragmentation of nitrogen-14 nuclei at 2.1 Gev per nucleon.

    Science.gov (United States)

    Heckman, H. H.; Greiner, D. E.; Lindstrom, P. J.; Bieser, F. S.

    1971-01-01

    An experiment has been carried out at the bevatron on the nuclear fragmentation of nitrogen-14 ions at an energy of 2.1 billion electron volts (Gev) per nucleon. Because of the near equality of the velocities of the nitrogen-14 beam and the fragmentation products at an angle of 0 deg, we find it possible to identify the nuclear fragments isotopically.

  6. nuclei

    Directory of Open Access Journals (Sweden)

    Minkov N.

    2016-01-01

    Full Text Available We study the effects of quadrupole-octupole deformations on the energy and magnetic properties of high-K isomeric states in even-even heavy and superheavy nuclei. The neutron two-quasiparticle (2qp isomeric energies and magnetic dipole moments are calculated within a deformed shell model with the Bardeen-Cooper- Schrieffer (BCS pairing interaction over a wide range of quadrupole and octupole deformations. We found that in most cases the magnetic moments exhibit a pronounced sensitivity to the octupole deformation, while the 2qp energies indicate regions of nuclei in which the presence of high-K isomeric states may be associated with the presence of octupole softness or even with octupole deformation. In the present work we also examine the influence of the BCS pairing strength on the energy of the blocked isomer configuration. We show that the formation of 2qp energy minima in the space of quadrupole-octupole and eventually higher multipolarity deformations is a subtle effect depending on nuclear pairing correlations.

  7. Fission fragments mass distributions of nuclei populated by the multinucleon transfer channels of the 18O+232Th reaction

    Directory of Open Access Journals (Sweden)

    R. Léguillon

    2016-10-01

    Full Text Available It is shown that the multinucleon transfer reactions is a powerful tool to study fission of exotic neutron-rich actinide nuclei, which cannot be accessed by particle-capture or heavy-ion fusion reactions. In this work, multinucleon transfer channels of the 18O+232Th reaction are used to study fission of fourteen nuclei 231,232,233,234Th, 232,233,234,235,236Pa, and 234,235,236,237,238U. Identification of fissioning nuclei and of their excitation energy is performed on an event-by-event basis, through the measurement of outgoing ejectile particle in coincidence with fission fragments. Fission fragment mass distributions are measured for each transfer channel, in selected bins of excitation energy. In particular, the mass distributions of 231,234Th and 234,235,236Pa are measured for the first time. Predominantly asymmetric fission is observed at low excitation energies for all studied cases, with a gradual increase of the symmetric mode towards higher excitation energy. The experimental distributions are found to be in general agreement with predictions of the fluctuation–dissipation model.

  8. Rapid experimental SAD phasing and hot-spot identification with halogenated fragments

    Directory of Open Access Journals (Sweden)

    Joseph D. Bauman

    2016-01-01

    Full Text Available Through X-ray crystallographic fragment screening, 4-bromopyrazole was discovered to be a `magic bullet' that is capable of binding at many of the ligand `hot spots' found in HIV-1 reverse transcriptase (RT. The binding locations can be in pockets that are `hidden' in the unliganded crystal form, allowing rapid identification of these sites for in silico screening. In addition to hot-spot identification, this ubiquitous yet specific binding provides an avenue for X-ray crystallographic phase determination, which can be a significant bottleneck in the determination of the structures of novel proteins. The anomalous signal from 4-bromopyrazole or 4-iodopyrazole was sufficient to determine the structures of three proteins (HIV-1 RT, influenza A endonuclease and proteinase K by single-wavelength anomalous dispersion (SAD from single crystals. Both compounds are inexpensive, readily available, safe and very soluble in DMSO or water, allowing efficient soaking into crystals.

  9. Properties of Hot and Fast Rotating Atomic Nuclei Studied by Means of Giant Dipole Resonance in Exclusive Experiments

    International Nuclear Information System (INIS)

    Maj, A.

    2000-01-01

    This work entitled ''Properties of hot and fast rotating atomic nuclei studied by means of Giant Dipole Resonance in exclusive experiments'', is the habilitation thesis of dr. Adam Maj. It consists of the review (in Polish) of performed research and of attached reprints from 16 original publications (in English) which A. Maj is the main or one of the main authors. All the studies were performed in collaboration with the groups from Milano and Copenhagen, using the HECTOR array equipment (described in chapter V). The Giant Dipole Resonance couples to the quadrupole degrees of freedom of the nucleus, and therefore constitutes a unique probe to test the shapes of atomic nuclei. In addition, the γ decay of the GDR from highly excited nuclei is a very fast process, it can compete with other modes of nuclear decay, and therefore can provide the information on the initial stages of excited nuclei. The presented investigations were concentrated on the following aspects: the shapes and thermal shape fluctuations, the origin of the behaviour of the GDR width, the properties of some exotic nuclei (Jacobi shapes, superdeformation, superheavy nuclei) and on ''entrance channel'' effects. The GDR γ decay was measured for nuclei with very different masses: from light nuclei with A≅45, through A≅110, 145,170,190, up to superheavy nuclei with A≅270. The shapes of hot nuclei are not fixed but fluctuate. The extent of these fluctuations and their influence on the measured quantities (GDR strength function, angular distribution and effective shape) is discussed in chapter VI.1. The observed width of the GDR is found to arise from the interplay of two effects: the thermal shape fluctuations, which are controlled by the nuclear temperature, and the deformation effects, controlled by the angular momentum. The ''collisional damping'' effect, which should influence the intrinsic GDR width, was found to be negligible (chapter VI.2). The GDR γ decay from hot superheavy nucleus 272 Hs

  10. Complex fragments from excited actinide nuclei. A new test of the finite range model

    International Nuclear Information System (INIS)

    Sarantities, D.G.; Bowman, D.R.; Wozniak, G.J.; Charity, R.J.; Liu, Z.H.; McDonald, R.J.; McMahan, M.A.; Moretto, L.G.

    1989-01-01

    Complex fragments ranging in charge from 7 ≤ Z ≤ 45 have been detected in binary coincidence following the reaction of 8.4 MeV/u 232 Th+ 12 C, and are shown to arise from the binary decay of a 244 Cm compound nucleus. This work confirms earlier radiochemical observations of very light fragments in the fission fragment mass distribution, establishes their binary character, and interprets their yield in terms of finite range potential energy barriers. (orig.)

  11. Complex fragments from excited actinide nuclei: A new test of the finite range model

    International Nuclear Information System (INIS)

    Sarantities, D.G.; Bowman, D.R.; Wozniak, G.J.; Charity, R.J.; Liu, Z.H.; McDonald, R.J.; McMahan, M.A.; Moretto, L.G.

    1988-05-01

    Complex fragments ranging in charge from 7≤Z≤45 have been detected in binary coincidence following the reaction of 8.4 MeV/u 232 Th+ 12 C, and are shown to arise from the binary decay of a 244 Cm compound nucleus. This work confirms earlier radiochemical observations of very light fragments in the fission fragment mass distribution, establishes their binary character, and interprets their yield in terms of finite range potential energy barriers. 15 refs., 3 figs

  12. Fragmentation cross sections of relativistic 8436Kr and 10947Ag nuclei in targets from hydrogen to lead

    International Nuclear Information System (INIS)

    Nilsen, B.S.; Waddington, C.J.; Cummings, J.R.; Garrard, T.L.; Klarmann, J.

    1995-01-01

    With the addition of krypton and silver projectiles we have extended our previous studies of the fragmentation of heavy relativistic nuclei in targets ranging in mass from hydrogen to lead. These projectiles were studied at a number of discrete energies between 450 and 1500A MeV. The total and partial charge-changing cross sections were determined for each energy, target, and projectile, and the values compared with previous predictions. A new parametrization of the dependence of the total charge-changing cross sections on the target and projectile is introduced, based on nuclear charge radii derived from electron scattering. We have also parametrized the energy dependence of the total cross sections over the range of energies studied. New parameters were found for a previous representation of the partial charge-changing cross sections in hydrogen and a new parametrization has been introduced for the nonhydrogen targets. The evidence that limiting fragmentation has been attained for these relatively light projectile nuclei at Bevalac energies is shown to be inconclusive, and further measurements at higher energies will be needed to address this question

  13. Fragmentation of 12C nuclei in emulsion at 50 GeV/c

    International Nuclear Information System (INIS)

    El-Naghy, A.

    1981-01-01

    A total of 852 12 C-emulsion interactions at 4.2 GeV/nucleon was investigated. In 86% of these events, at least one projectile fragment was oberserved in each. The angular distributions of Z = 1,2, and >= 3 projectile fragments are narrow, and the dispersion of the distribution decreases with the increasing of Z. The production cross section of the reaction 12 C + Em → Li (from the projectile) + anything is about 6 x 10 -3 sigmasub(in). Only the projectile-fragmentation events, nsub(h) = O, were studied in detail; the percentage of these events is 10% of the total inelastic events. The events with the maximum probability are those in which α-fragment is the maximum-charged projectile fragment emitted. This indicates that the projectile nuclear structure plays an important role in the fragmentation process. In 1.2% of the total events, 12 C has been dissociated into 3 α-particles. (orig.)

  14. Temperature and excitation energy of hot nuclei in the reaction of 40Ar+197Au at 25 MeV/nucleon

    International Nuclear Information System (INIS)

    Wu, H.; Jin, G.; Li, Z.; Dai, G.; Qi, Y.; He, Z.; Luo, Q.; Duan, L.; Wen, W.; Zhang, B.

    1997-01-01

    The coincidence measurements between heavy fission fragments and light charged particles with Z ≤2 were carried out for the 40 Ar+ 197 Au reaction at 25 MeV/nucleon, to study the properties of hot nuclei in heavy ion induced reactions. The linear momentum transfers (LMTs) were deduced from the folding angle and the time-of-flight difference between two fission fragments of heavy residues. The relationship of the nuclear temperature (slope parameter of the energy spectrum) and the excitation energy was determined independently from the measurement of the kinetic energy spectra in the frames of the emitting sources and from the LMT analysis. Both the temperature and the excitation energy increase with decreasing impact parameter, which suggests that a plateau temperature of 5.5 MeV is reached at an excitation energy of 3.1 MeV/nucleon. The result was also compared with various statistical models that explain the plateau by the multifragmentation process, where the excitation energy is assumed to be stored in compression and expansion effects. (orig.)

  15. Detection of ligand binding hot spots on protein surfaces via fragment-based methods: application to DJ-1 and glucocerebrosidase

    Energy Technology Data Exchange (ETDEWEB)

    Landon, Melissa R.; Lieberman, Raquel L.; Hoang, Quyen Q.; Ju, Shulin; Caaveiro, Jose M.M.; Orwig, Susan D.; Kozakov, Dima; Brenke, Ryan; Chuang, Gwo-Yu; Beglov, Dmitry; Vajda, Sandor; Petsko, Gregory A.; Ringe, Dagmar; (BU-M); (Brandeis); (GIT)

    2010-08-04

    The identification of hot spots, i.e., binding regions that contribute substantially to the free energy of ligand binding, is a critical step for structure-based drug design. Here we present the application of two fragment-based methods to the detection of hot spots for DJ-1 and glucocerebrosidase (GCase), targets for the development of therapeutics for Parkinson's and Gaucher's diseases, respectively. While the structures of these two proteins are known, binding information is lacking. In this study we employ the experimental multiple solvent crystal structures (MSCS) method and computational fragment mapping (FTMap) to identify regions suitable for the development of pharmacological chaperones for DJ-1 and GCase. Comparison of data derived via MSCS and FTMap also shows that FTMap, a computational method for the identification of fragment binding hot spots, is an accurate and robust alternative to the performance of expensive and difficult crystallographic experiments.

  16. Multiple parton scattering in nuclei: heavy quark energy loss and modified fragmentation functions

    International Nuclear Information System (INIS)

    Zhang Benwei; Wang, Enke; Wang Xinnian

    2005-01-01

    Multiple scattering, induced radiative energy loss and modified fragmentation functions of a heavy quark in nuclear matter are studied within the framework of generalized factorization in perturbative QCD. Modified heavy quark fragmentation functions and energy loss are derived in detail with illustration of the mass dependencies of the Landau-Pomeranchuk-Migdal interference effects and heavy quark energy loss. Due to the quark mass dependence of the gluon formation time, the nuclear size dependencies of nuclear modification of the heavy quark fragmentation function and heavy quark energy loss are found to change from a linear to a quadratic form when the initial energy and momentum scale are increased relative to the quark mass. The radiative energy loss of the heavy quark is also significantly suppressed due to limited cone of gluon radiation imposed by the mass. Medium modification of the heavy quark fragmentation functions is found to be limited to the large z region due to the form of heavy quark fragmentation functions in vacuum

  17. A reconsideration of fission fragment angular distributions from nuclei of high spin

    International Nuclear Information System (INIS)

    Vaz, L.C.; Alexander, J.M.

    1983-01-01

    It has often been stated that fission fragment angular anisotropy, as predicted by equilibrium statistical theory, should disappear with increasing spin of the composite nucleus. However, several recent experimental studies reveal strong anisotropies for fission fragments from high-spin nuclear systems. We discuss this apparent discrepancy and its relationship to the rigid-rotor approximation used in the standard theory. A systematic comparison is given for fission fragment anisotropies from many experiments via the empirical parameters K 0 2 and Ssub(eff). These systematics indicate a strong regularity, provided one allows for the perturbing effects of fission after transfer reactions. Many of the observed anisotropies exceed the predictions of the standard theory, but, as these predictions are based on a rigid rotor model, this does not seem particularly noteworthy. (orig.)

  18. Peripheral collisions of 2 GeV/nucleon Fe nuclei in nuclear emulsion. I. Light projectile fragments

    International Nuclear Information System (INIS)

    Friedlander, E.M.; Crawford, H.J.; Gimpel, R.W.; Greiner, D.E.; Heckman, H.H.; Lindstrom, P.J.

    1978-01-01

    Observations on 374 collisions of 1.88-GeV/nucleon Fe nuclei in Ilford G-5 nuclear track emulsion, in which at least one projectle fragment of Z > = 3 was emitted within a 6 0 cone, revealed several features of projectile breakup. The onset of copious multiple fragmentation was observed. The relatively high α-particle multiplicities allowed for the first time a study of the α multiplicity distribution; a Poisson distribution gave an excellent fit. The data showed a significant enhancement of α-particle pairs with very small relative momenta. The transverse momentum distributions, which should reflect best the thermal motion in the projectile system, are in flagrant discrepancy with theoretical predictions; the distributions show a marked target dependence. The charges of all projectile fragments up to B were determined by measurement of gap-length distributions. Events with N/sub h/ = 0 are a class apart from the rest of the events; between N/sub h/ = 1 and N/sub h/ = 9 there is surprisingly little change in most parameters. 4 figures

  19. Evaporation residue cross sections for the {sup 64}Ni + {sup 144,154}Sm reaction -- Energy dissipation in hot nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Back, B.B.; Blumenthal, D.J.; Davids, C.N. [and others

    1995-08-01

    The fission hindrance of hot nuclei was deduced recently from an enhanced emission of GDR {gamma} rays, neutrons and charged particles prior to scission of heavy nuclei. In the most recent experiments addressing this topic, namely new measurements of the pre-scission {gamma} rays and evaporation residues from the {sup 32}S + {sup 184}W reaction, a rather sharp transition from negligible to full one-body dissipation occurs over the excitation energy region E{sub exc} = 60-100 MeV. However, the cross section does not appear to level out or start to decline again at the upper end of the energy range as expected in this interpretation. It is therefore clearly desirable to extend the excitation energy range to look for such an effect in order to either corroborate or refute this interpretation.

  20. Rapid experimental SAD phasing and hot-spot identification with halogenated fragments

    Energy Technology Data Exchange (ETDEWEB)

    Bauman, Joseph D.; Harrison, Jerry Joe E. K.; Arnold, Eddy

    2016-01-01

    Through X-ray crystallographic fragment screening, 4-bromopyrazole was discovered to be a `magic bullet' that is capable of binding at many of the ligand `hot spots' found in HIV-1 reverse transcriptase (RT). The binding locations can be in pockets that are `hidden' in the unliganded crystal form, allowing rapid identification of these sites forin silicoscreening. In addition to hot-spot identification, this ubiquitous yet specific binding provides an avenue for X-ray crystallographic phase determination, which can be a significant bottleneck in the determination of the structures of novel proteins. The anomalous signal from 4-bromopyrazole or 4-iodopyrazole was sufficient to determine the structures of three proteins (HIV-1 RT, influenza A endonuclease and proteinase K) by single-wavelength anomalous dispersion (SAD) from single crystals. Both compounds are inexpensive, readily available, safe and very soluble in DMSO or water, allowing efficient soaking into crystals.

  1. Beryllium isotopes in primary cosmic radiation and light nuclei fragmentation observed in plastic detectors

    International Nuclear Information System (INIS)

    Fukui, Katsura.

    1975-01-01

    Plastic sheets consisting of 50 layers of Daicel and Kodak cellulose nitrate were flown from Fort Churchill, Canada in 1971 for the study of isotopic components of light nuclei, especially beryllium, in primary cosmic rays. In this plastic stack, 59 Be normals and 24 Be albedos as well as 109 Li normals and 53 Li albedos were identified. The center of mass and the standard deviation for Be 7 and Be 9+10 may be derived from the mass spectrum. (orig./WL) [de

  2. Role of compound nuclei in intermediate-energy heavy-ion reactions

    International Nuclear Information System (INIS)

    Moretto, L.G.; Wozniak, G.J.

    1988-05-01

    Hot compound nuclei are frequently produced in intermediate-energy reactions through a variety of processes. Their decay is shown to be an important and at times dominant source of complex fragments, high energy-gamma rays, and even pions

  3. Compound nuclei, binary decay, and multifragmentation in intermediate-energy heavy-ion reactions

    International Nuclear Information System (INIS)

    Moretto, L.G.; Wozniak, G.J.

    1988-07-01

    Hot compound nuclei, frequently produced in intermediate-energy reactions through a variety of processes, are shown to be an important and at times dominant source of complex fragments. 13 refs., 12 figs

  4. Non-statistical fluctuations in fragmentation of target nuclei in high energy nuclear interactions

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, Dipak; Ghosh, Premomoy; Ghosh, Alokananda; Roy, Jaya [Jadavpur Univ., Calcutta (India)

    1994-07-01

    Analysis of target fragmented ''black'' particles in nuclear emulsion from high energy relativistic interactions initiated by [sup 16]O at 2.1 GeV/nucleon and [sup 12]C and [sup 24]Mg at 4.5 GeV/nucleon reveal the existence of non-statistical fluctuations in the azimuthal plane of interaction. The asymmetry or the non-statistical fluctuations, while found to be independent of projectile mass or incident energy, are dependent on the excitation energy of the target nucleus. (Author).

  5. Non-statistical fluctuations in fragmentation of target nuclei in high energy nuclear interactions

    International Nuclear Information System (INIS)

    Ghosh, Dipak; Ghosh, Premomoy; Ghosh, Alokananda; Roy, Jaya

    1994-01-01

    Analysis of target fragmented ''black'' particles in nuclear emulsion from high energy relativistic interactions initiated by 16 O at 2.1 GeV/nucleon and 12 C and 24 Mg at 4.5 GeV/nucleon reveal the existence of non-statistical fluctuations in the azimuthal plane of interaction. The asymmetry or the non-statistical fluctuations, while found to be independent of projectile mass or incident energy, are dependent on the excitation energy of the target nucleus. (Author)

  6. The systematics of the deexcitation of hot nuclei and the onset of multibody decay

    International Nuclear Information System (INIS)

    Bowman, D.R.; Peaslee, G.F.; Colonna, N.

    1989-03-01

    Results from the asymmetric reactions 80 and 100 MeV/uLa + C are presented and compared to earlier work with the same system at 18 and 50 MeV/u. Fragment-fragment correlations, cross sections, and distributions in velocity space indicate the continued dominance of a quasi-binary decay mechanism with increased emission of light charged particles. The distributions in velocity also indicate a progression toward a ''fireball'' type of reaction mechanism. However, the angular distributions of the emitted fragments are incompatible with statistical production mechanisms that have successfully explained the lower energy results, and indicate the dynamical nature of the emission process. Dalitz plots of triple complex fragment coincidences are presented in order to investigate the nature of the multibody decays. 18 refs., 9 figs

  7. The statistical decay of very hot nuclei: from sequential decay to multifragmentation

    International Nuclear Information System (INIS)

    Carlson, B.V.; Donangelo, R.; Universidad de la Republica, Montevideo; Souza, S.R.; Universidade Federal do Rio Grande do Sul; Lynch, W.G.; Steiner, A.W.; Tsang, M.B.

    2010-01-01

    Full text. At low excitation energies, the compound nucleus typically decays through the sequential emission of light particles. As the energy increases, the emission probability of heavier fragments increases until, at sufficiently high energies, several heavy complex fragments are emitted during the decay. The extent to which this fragment emission is simultaneous or sequential has been a subject of theoretical and experimental study for almost 30 years. The Statistical Multifragmentation Model, an equilibrium model of simultaneous fragment emission, uses the configurations of a statistical ensemble to determine the distribution of primary fragments of a compound nucleus. The primary fragments are then assumed to decay by sequential compound emission or Fermi breakup. As the first step toward a more unified model of these processes, we demonstrate the equivalence of a generalized Fermi breakup model, in which densities of excited states are taken into account, to the microcanonical version of the statistical multifragmentation model. We then establish a link between this unified Fermi breakup / statistical multifragmentation model and the well-known process of compound nucleus emission, which permits to consider simultaneous and sequential emission on the same footing. Within this unified framework, we analyze the increasing importance of simultaneous, multifragment decay with increasing excitation energy and decreasing lifetime of the compound nucleus. (author)

  8. Formation and decay of hot nuclei in the 64Zn + 48Ti reactions from 35 to 79 MeV/u

    International Nuclear Information System (INIS)

    Steckmeyer, J.C.

    1995-01-01

    The 4π plastic multidetector of NAUTILUS has been used to detect charged products of the collisions in the reactions of 64 Zn with 48 Ti from 35 to 79 MeV/u. Well measured events were selected and sorted as a function of the impact parameter. The primary mass of the fast source as well as its excitation energy have been carefully reconstructed from the characteristics of the disintegration products after separation of both the pre-equilibrium and the target emission. The isotropic emission of particles in the frame of the primary hot nucleus suggests that thermal equilibrium has been achieved. The excitation energy increases from peripheral to central collisions, with values reaching more than 10 MeV/u at the highest bombarding energy. Experimental multiplicities and relative velocity distributions of intermediate mass fragments will be compared to theoretical predictions of both statistical and dynamical models. Differences between data and calculations suggest the existence of a radial expansion of the hottest nuclei

  9. Formation and decay of hot nuclei in 40 Ca + ''40 Ca at 35 MeV/nucleon

    International Nuclear Information System (INIS)

    Planeta, R.; Gawlikowicz, W.; Grotowski, K.

    2000-01-01

    Properties of multifragmentation of 'hot sources' produced in the 40 Ca + 40 Ca reaction have been studied at a beam energy of 35 MeV/nucleon. Two signatures of prompt multifragmentation which make use of special features of particle emission from the 'freeze out volume' together with an analysis of the reduced relative velocity between pairs of intermediate mass fragments indicate the presence of a transition from the sequential decay to prompt multifragmentation at an excitation energy of about 3 MeV/nucleon. (authors)

  10. Use of reverse kinematics in the identification of large fragments evaporated by compound nuclei

    International Nuclear Information System (INIS)

    Sobotka, L.G.; McMahan, M.A.; McDonald, R.J.

    1985-01-01

    Fragments ranging in charge from Z = 2 to Z = Z/sub symmetry/ have been identified from the compound nucleus decay associated with a variety of heavy ion reactions. The use of reverse kinematics (projectile heavier than the target) was crucial in performing these measurements. The experiments were carried out at the SuperHILAC utilizing beams of 550 MeV 74 Ge, 782 MeV 93 Nb and 1157 MeV 139 La, to bombard targets of 0.54 mg/cm 2 12 C and 1.0 mg/cm 2 9 Be. The detection system consisted of four solid state ΔE-E silicon telescopes (40-70 μm, 3-5 mm) situated at 7.5 0 , 15 0 , 25 0 , and 35 0 from the beam with solid angles of approximately 1.0 msr. For the heavier 139 La beam these detectors were supplemented by two gas ΔE - solid state E telescopes at -7.5 0 and -22.5 0

  11. The limiting temperature of hot nuclei from microscopic equation of state

    International Nuclear Information System (INIS)

    Baldo, M.; Ferreira, L.S.; Nicotra, O.E.

    2004-01-01

    The limiting temperature T lim of a series of nuclei is calculated employing a set of microscopic nuclear equations of state (EOS's). It is shown that the value of T lim is sensitive to the nuclear matter equation of state used. Comparison with the values extracted in recent phenomenological analysis appears to favor a definite selection of EOS's. On the basis of this phenomenological analysis, it therefore seems possible to check the microscopic calculations of the nuclear EOS at finite temperature, which is hardly accessible through other experimental information

  12. The Skyrme-TQRPA calculations of electron capture on hot nuclei in pre-supernova environment

    Energy Technology Data Exchange (ETDEWEB)

    Dzhioev, Alan A., E-mail: dzhioev@theor.jinr.ru; Vdovin, A. I., E-mail: vdovin@theor.jinr.ru [JINR, Bogoliubov Laboratory of Theoretical Physics (Russian Federation); Stoyanov, Ch., E-mail: stoyanov@inrne.bas.bg [Bulgarian Academy of Sciences, Institute for Nuclear Research and Nuclear Energy (Bulgaria)

    2016-11-15

    We combine the thermal QRPA approach with the Skyrme energy density functional theory (Skyrme–TQRPA) for modelling the process of electron capture on nuclei in supernova environment. For a sample nucleus, {sup 56}Fe, the Skyrme–TQRPA approach is applied to analyze thermal effects on the strength function of GT{sub +} transitions which dominate electron capture at E{sub e} ≤ 30 MeV. Several Skyrme interactions are used in order to verify the sensitivity of the obtained results to the Skyrme force parameters. Finite-temperature cross sections are calculated and the results are comparedwith those of the other model calculations.

  13. Nonperturbative study of the damping of giant resonances in hot nuclei

    International Nuclear Information System (INIS)

    De Blasio, F.V.; Cassing, W.; Tohyama, M.; Bortignon, P.F.; Broglia, R.A.

    1992-01-01

    The damping of dipole and quadrupole motion in 16 O and 40 Ca at zero and finite temperature is studied including particle-particle and particle-hole interactions to all orders of perturbation. We find that the dipole dynamics in these light nuclei is well described in terms of mean-field theory (time-dependent Hartree-Fock), while the quadrupole motion is strongly damped through the coupling to more complicated configurations. Both the centroid and the damping width of the quadrupole and dipole giant resonances show a clear stability with temperature as a consequence of the weakening of the interaction, which contrasts with the increase of the phase space

  14. Hot nuclei production in Ar+Ag reactions at 50 and 70 MeV/u: limits of decay standard mode

    International Nuclear Information System (INIS)

    Vient, E.

    1992-04-01

    The experiment discussed in this thesis is devoted to the study of hot nuclei produced in the Ar + Ag collisions at 50 and 70 MeV per nucleon. Special emphasis has been given to the standard decay of these nuclei, i.e. to the sequential evaporation process leading to a heavy residue. The experimental set up has been triggered by a residue detector and all the evaporated light charged particles have been detected in a large area set up covering nearly the whole space. It has been possible to sort all the detected particles and to isolate those evaporated from the initial hot nuclei, the initial characteristics of which have been reconstructed. Two important features have been stressed: - A shot nuclei can sustain an excitation energy of 6 MeV/a and a temperature of 8 MeV without disintegrating completely. - The distributions of excitation energy stored at 50 and 70 MeV/nucleon are similar. This result can refled either an entrance channel property or a hot nuclei behaviour. Further results obtained in this work give arguments supporting the first interpretation

  15. Life-time of hot nuclei; Temps de vie des noyaux chauds

    Energy Technology Data Exchange (ETDEWEB)

    Aboufirassi, M.; Bougault, R.; Brou, R.; Colin, J.; Durand, D.; Genoux-Lubain, A.; Horn, D.; Laville, J.L.; Le Brun, C.; Lecolley, J.F.; Lopez, O.; Louvel, M.; Mahi, M.; Meslin, C.; Steckmeyer, J.C.; Tamain, B. [Lab. de Physique Corpusculaire, Caen Univ., 14 (France); LPC (Caen) - CRN (Strasbourg) - IPN (Orsay) - GANIL Collaboration

    1998-04-01

    The study of the systems Ne + Au, Ar + Au and Kr + Au has allowed description of the de-excitation and particularly the evolution of the fragment emission time intervals as o function of the compound system excitation energy. The analysis of data obtained by the multidetector NAUTILUS for Pb + Au at 29 MeV/u has permitted the access to another time scale: the lifetime of the two partners before fragmentation. For this system and this energy the predominant process is primarily a two-body process analogue to that observed at lower energies (deep inelastic transfer). This mechanism can lead to a complete relaxation energy and consequently to low relative velocities between the two partners in the exit channel. In contrast to the low energy process where the two partners decay by evaporation, here the energy implied may lead to the rupture of one and/or the other partner in several fragments (2 to 5). For the the most relaxed events the excitation energies may reach the values of 6 MeV/u. Simulations were realized in which the entrance channel i.e. the relaxation of the two partners is described by a classical trajectory calculation. In the exit channel after a time {tau} one of the two partners splits in several fragments. The study of the trajectories of these fragments allows the determination of the angular distributions relative to the direction of the un-split partner. The comparison between this calculation and the data is given. The {tau} values vary from a negative value corresponding to a rupture during the interaction of two partners up to a {tau} of 200 fm/c. The best fit indicates a {tau} 100 fm/c, this showing that the lifetime of the splitting nucleus is of the order of 100 fm/c after separation of the two partners. By comparing this result with microscopic models one can obtain a better understanding of the system rupture scenario. This study is under way 4 refs.

  16. Total reaction cross sections and neutron-removal cross sections of neutron-rich light nuclei measured by the COMBAS fragment-separator

    Science.gov (United States)

    Hue, B. M.; Isataev, T.; Erdemchimeg, B.; Artukh, A. G.; Aznabaev, D.; Davaa, S.; Klygin, S. A.; Kononenko, G. A.; Khuukhenkhuu, G.; Kuterbekov, K.; Lukyanov, S. M.; Mikhailova, T. I.; Maslov, V. A.; Mendibaev, K.; Sereda, Yu M.; Penionzhkevich, Yu E.; Vorontsov, A. N.

    2017-12-01

    Preliminary results of measurements of the total reaction cross sections σR and neutron removal cross section σ-xn for weakly bound 6He, 8Li, 9Be and 10Be nuclei at energy range (20-35) A MeV with 28Si target is presented. The secondary beams of light nuclei were produced by bombardment of the 22Ne (35 A MeV) primary beam on Be target and separated by COMBAS fragment-separator. In dispersive focal plane a horizontal slit defined the momentum acceptance as 1% and a wedge degrader of 200 μm Al was installed. The Bρ of the second section of the fragment-separator was adjusted for measurements in energy range (20-35) A MeV. Two-neutron removal cross sections for 6He and 10Be and one -neutron removal cross sections 8Li and 9Be were measured.

  17. Hot zone evolution and pre-equilibrium emission in interactions between nuclei

    International Nuclear Information System (INIS)

    Jakobsson, B.; Karlsson, L.

    1990-01-01

    The evolution of the hot- and cold zones in intermediate energy nucleus-nucleus collisions by means of spherically expanding volumes and transport equations based on the Fermi-Dirac equation of state is described. Though the dynamical evolution of the collision is similar to that in Vlasov-Uehling-Uhlenbeck (VUU) calculations, some differences in the spectral shapes of emitted nucleons are found. The pre-equilibrium particle emission, prior to the breakup- or to the evaporation stage is always found to be an important contribution to the nucleon spectra which show reasonable agreement with data. (orig.)

  18. Critical temperature for shape transition in hot nuclei within covariant density functional theory

    Science.gov (United States)

    Zhang, W.; Niu, Y. F.

    2018-05-01

    Prompted by the simple proportional relation between critical temperature for pairing transition and pairing gap at zero temperature, we investigate the relation between critical temperature for shape transition and ground-state deformation by taking even-even Cm-304286 isotopes as examples. The finite-temperature axially deformed covariant density functional theory with BCS pairing correlation is used. Since the Cm isotopes are the newly proposed nuclei with octupole correlations, we studied in detail the free energy surface, the Nilsson single-particle (s.p.) levels, and the components of s.p. levels near the Fermi level in 292Cm. Through this study, the formation of octupole equilibrium is understood by the contribution coming from the octupole driving pairs with Ω [N ,nz,ml] and Ω [N +1 ,nz±3 ,ml] for single-particle levels near the Fermi surfaces as it provides a good manifestation of the octupole correlation. Furthermore, the systematics of deformations, pairing gaps, and the specific heat as functions of temperature for even-even Cm-304286 isotopes are discussed. Similar to the relation between the critical pairing transition temperature and the pairing gap at zero temperature Tc=0.6 Δ (0 ) , a proportional relation between the critical shape transition temperature and the deformation at zero temperature Tc=6.6 β (0 ) is found for both octupole shape transition and quadrupole shape transition for the isotopes considered.

  19. Can we really measure the internal energy of hot nuclei with a 4 π detection array?

    International Nuclear Information System (INIS)

    Vient, E.; Genouin-Duhamel, E.; Steckmeyer, J.C.

    2001-10-01

    The second generation of high quality detection arrays gave hope to nuclear physicists to finally obtain an experimental equation of state of nuclear matter. In spite of this progress, the measurement of the internal energy of a hot nucleus remains a very difficult task. This paper illustrates this difficulty by a methodological study of a classical technique of excitation energy measurement used in the Fermi energy range. The aim of this study is to verify the validity, the accuracy and the experimental limits of these measurements. It is shown that it is difficult to have a real experimental mastery of the source reconstruction and calorimetry at least for limited bombarding energies and violent collisions. (authors)

  20. Can we really measure the internal energy of hot nuclei with a 4 {pi} detection array?

    Energy Technology Data Exchange (ETDEWEB)

    Vient, E.; Genouin-Duhamel, E.; Steckmeyer, J.C. [and others

    2001-10-01

    The second generation of high quality detection arrays gave hope to nuclear physicists to finally obtain an experimental equation of state of nuclear matter. In spite of this progress, the measurement of the internal energy of a hot nucleus remains a very difficult task. This paper illustrates this difficulty by a methodological study of a classical technique of excitation energy measurement used in the Fermi energy range. The aim of this study is to verify the validity, the accuracy and the experimental limits of these measurements. It is shown that it is difficult to have a real experimental mastery of the source reconstruction and calorimetry at least for limited bombarding energies and violent collisions. (authors)

  1. Hot and dense matter in compact stars - from nuclei to quarks

    International Nuclear Information System (INIS)

    Hempel, Matthias

    2010-01-01

    This dissertation deals with the equation of state of hot and dense matter in compact stars, with special focus on first order phase transitions. A general classification of first order phase transitions is given and the properties of mixed phases are discussed. Aspects of nucleation and the role of local constraints are investigated. The derived theoretical concepts are applied to matter in neutron stars and supernovae, in the hadron-quark and the liquid-gas phase transition. For the detailed description of the liquid-gas phase transition a new nuclear statistical equilibrium model is developed. It is based on a thermodynamic consistent implementation of relativistic mean-field interactions and excluded volume effects. With this model different equation of state tables are calculated and the composition and thermodynamic properties of supernova matter are analyzed. As a first application numerical simulations of core-collapse supernovae are presented. For the hadron-quark phase transition two possible scenarios are studied in more detail. First the appearance of a new mixed phase in a proto neutron star and the implications on its evolution. In the second scenario the consequences of the hadron-quark transition in corecollapse supernovae are investigated. Simulations show that the appearance of quark matter has clear observable signatures and can even lead to the generation of an explosion. (orig.)

  2. Hot and dense matter in compact stars - from nuclei to quarks

    Energy Technology Data Exchange (ETDEWEB)

    Hempel, Matthias

    2010-10-19

    This dissertation deals with the equation of state of hot and dense matter in compact stars, with special focus on first order phase transitions. A general classification of first order phase transitions is given and the properties of mixed phases are discussed. Aspects of nucleation and the role of local constraints are investigated. The derived theoretical concepts are applied to matter in neutron stars and supernovae, in the hadron-quark and the liquid-gas phase transition. For the detailed description of the liquid-gas phase transition a new nuclear statistical equilibrium model is developed. It is based on a thermodynamic consistent implementation of relativistic mean-field interactions and excluded volume effects. With this model different equation of state tables are calculated and the composition and thermodynamic properties of supernova matter are analyzed. As a first application numerical simulations of core-collapse supernovae are presented. For the hadron-quark phase transition two possible scenarios are studied in more detail. First the appearance of a new mixed phase in a proto neutron star and the implications on its evolution. In the second scenario the consequences of the hadron-quark transition in corecollapse supernovae are investigated. Simulations show that the appearance of quark matter has clear observable signatures and can even lead to the generation of an explosion. (orig.)

  3. Emission of light charged particles from fragments produced on fission of uranium nuclei by 153 MeV protons and 1700 MeV negative pions

    International Nuclear Information System (INIS)

    Belovitzky, G.E.; Shteingrad, O.M.

    2000-01-01

    The mechanism underlying the emission of light charged particles (LCP) with Z = 1, 2 from fragments produced in fission of uranium nuclei by 153 MeV protons and 1700 MeV negative pions was studied. It was found that LCP accompanying the fission by pions are emitted from non-accelerated fragments immediately after the fission, whereas in the case of 153 MeV protons, the LCP are emitted from the accelerated heavy fragments. The number of LCP emitted in the course of pion-induced fission is 0.7 per fission event, which exceeds by a factor of 30 the corresponding number for 153 MeV protons [ru

  4. Coherent fragmentation of 12C nuclei of momentum 4.5 GeV/ c per nucleon through the 8Beg.s.+4He channel in a nuclear photoemulsion containing lead nuclei

    Science.gov (United States)

    Belaga, V. V.; Gerasimov, S. G.; Dronov, V. A.; Peresadko, N. G.; Pisetskaya, A. V.; Rusakova, V. V.; Fetisov, V. N.; Kharlamov, S. P.; Shesterkina, L. N.

    2017-07-01

    A two-particle channel in which an unbound nucleus of 8Be in the ground state (8Beg.s.) was one of the fragments was selected among events where 12C nuclei of momentum 4.5 GeV/c per nucleon undergo coherent dissociation into three alpha particles. The events in question were detected in a track nuclear photoemulsion containing lead nuclei, which was irradiated at the synchrophasotron of the Laboratory of High Energies at the Joint Institute for Nuclear Research (JINR, Dubna). The average transverse momentum of alpha particles produced upon the decay of 8Beg.s. nuclei was 87±6 MeV/ c, while that for "single" alpha (αs) particles was 123±15 MeV/ c. The average value of the transverse-momentum transfer in the reaction being considered, Pt(12C), was 223 ± 20 MeV/ c. The average value of the cross section for this channel involving Ag and Br target nuclei was 13 ± 4 mb, while the cross section for the reaction on the Pb nucleus was 40 ± 15 mb. The Coulomb dissociation contribution evaluated on the basis of the number of events where the momentum P t(12C) did not exceed 0.1 GeV/c saturated about 20%. In nine events, the measured total transverse energy of the fragments in the reference frame comoving with the decaying carbon nucleus did not exceed 0.45 MeV, which did not contradict the excitation of the participant 12C nucleus to the level at 7.65 MeV. The average value of the transverse momentum in those events was 234 ± 25 MeV/ c.

  5. The Fragmentation of Heavy Nuclei by 13.8 GeV/c Protons as a Contribution to the Study of the Interaction Mechanism and Nuclear Structure

    International Nuclear Information System (INIS)

    Gil Perez, D.

    1967-01-01

    We present he re an global study of the interaction between high- energy particles and heavy nuclei, an interaction which holds obvious interest in relation to the problems of nuclear fragmentation and which, up lo now has only been studied piecemeal. We have used three stacks of photographic emulsions which were irradiated by 13.8 GeV/c protons, 17 GeV/c negative pions and 24 GeV/c protons. All three irradiations took place in a 180 K.G. magnetic field using CERN beams. (Author) 20 refs

  6. Numerical simulation of fragmentation of hot metal and oxide melts with the computer code IVA3

    International Nuclear Information System (INIS)

    Mussa, S.; Tromm, W.

    1994-01-01

    The phenomena of fragmentation of melts caused by water-inlet from the bottom with the computer code IVA3/11,12,13/ are investigated. With the computer code IVA3 three-component-multiphase flows can be numerically simulated. Two geometrical models are used. Both consist of a cylindrical vessel for water lying beneath a cylindrical vessel for melt. The vessels are connected to each other through a hole. Steel and UO 2 melts are. The following parameters were varied: the type of the melt (steel,UO 2 ), the water supply pressure and the geometry of the hole in the bottom plate through which the water and melt vessels are connected. As results of the numerical simulations temperature and pressure versus time curves are plotted. Additionally the volume flow rates and the volume fractions of the various phases in the vessels and the increase in surface and enthalpy of the melt during the time of simulation are depicted. With steel melts the rate of fragmentation increases with increasing water pressure and melt temperature, whereby stable channels are formed in the melt layer showing a very low flow resistance for steam. With UO 2 the formations of channels are also observed. However, these channels are not so stable that they eventually break apart and lead to the fragmentation of the UO 2 melt in drops. The fragmentation of the steel melt in water vessel is less than that of UO 2 . No essential solidification of the melt is observed in the respective duration of the simulations. However, a small drop in the melt temperature is observed. With a slight or no water pressure the melt flows from the upper vessel into the water vessel via the connecting hole. The processes take place in a very slow manner and with such a low steam production so that despite the occuring pressure peaks no sign of steam explosions could be observed. (orig./HP) [de

  7. Study of momentum distributions for projectile fragments of 22Ne and 28Si nuclei in collisions with emulsion

    International Nuclear Information System (INIS)

    Abou-Steit, S.A.H.

    2000-01-01

    The charge and mass yield curves and the momentum distributions of the projectile fragments produced in the interactions of 4.1 A GeV/c 22 Ne and 4.5 A GeV/c 28 Si with emulsion have been studied. The overall charge distributions of the projectile fragments resulting from these interactions are presented. The dependence of the mass yield distributions of the projectile fragments on the impact parameter has been tested. The momentum distributions for the considered reactions have been investigated by two methods. First, the projected momentum distributions in the plane of the microscope have been achieved by fitting the projected angular distributions to gaussian ones. It has been found that the width of the distribution changes with the charge of the projectile fragment and it decreases with the increase of the projectile fragment charge. Secondly, the transverse momentum distributions have been compared with previous studies. The momentum distribution, in the forward cone, is a typically narrow gaussian one

  8. Fission of heavy nuclei: microscopic study of fission barriers and fragments angular momentum; Fission des noyaux lourds: etude microscopique des barrieres de fission et du moment angulaire des fragments

    Energy Technology Data Exchange (ETDEWEB)

    Bonneau, L

    2003-11-01

    A lot of experimental data on nuclear fission has been being collected for the last 65 years, allowing theoreticians to confront their models with reality. The first part of this work is dedicated to the computation of fission barriers. We have extended the HF + BCS (Hartree Fock + Bandeen-Cooper-Schrieffer) method in order to include a new set of polynomials on which wave functions can be broken to, more accurately than on Hermite's polynomials in the 2 fragment configuration. The fission barriers of 26 heavy nuclei from Thorium-230 to Nobelium-256 have been assessed and compared to experimental data, it appears that differences are no greater than 1 MeV. We have discovered a neat correlation between the variation of the experimental fission lifetimes of even Fermium isotopes and the computed heights of second barriers. Moreover our model reproduces the hyper-deformed well of Thorium-230 with a good agreement on the well depth. The second part deals with the scission region. We have performed Hartree-Fock calculations in order to explore different ways of fragmentation. We have shown that the harmonic oscillator gives a valid description of such ways. In order to compute the mean value of J{sup 2} in the fragments we have been driven to propose an adequate definition of that quantity consistent with the non-locality property of the J{sup 2} operator. (A.C.)

  9. Fission of heavy nuclei: microscopic study of fission barriers and fragments angular momentum; Fission des noyaux lourds: etude microscopique des barrieres de fission et du moment angulaire des fragments

    Energy Technology Data Exchange (ETDEWEB)

    Bonneau, L

    2003-11-01

    A lot of experimental data on nuclear fission has been being collected for the last 65 years, allowing theoreticians to confront their models with reality. The first part of this work is dedicated to the computation of fission barriers. We have extended the HF + BCS (Hartree Fock + Bandeen-Cooper-Schrieffer) method in order to include a new set of polynomials on which wave functions can be broken to, more accurately than on Hermite's polynomials in the 2 fragment configuration. The fission barriers of 26 heavy nuclei from Thorium-230 to Nobelium-256 have been assessed and compared to experimental data, it appears that differences are no greater than 1 MeV. We have discovered a neat correlation between the variation of the experimental fission lifetimes of even Fermium isotopes and the computed heights of second barriers. Moreover our model reproduces the hyper-deformed well of Thorium-230 with a good agreement on the well depth. The second part deals with the scission region. We have performed Hartree-Fock calculations in order to explore different ways of fragmentation. We have shown that the harmonic oscillator gives a valid description of such ways. In order to compute the mean value of J{sup 2} in the fragments we have been driven to propose an adequate definition of that quantity consistent with the non-locality property of the J{sup 2} operator. (A.C.)

  10. Investigation of the heavy nuclei fission with anomalously high values of the fission fragments total kinetic energy

    Science.gov (United States)

    Khryachkov, Vitaly; Goverdovskii, Andrei; Ketlerov, Vladimir; Mitrofanov, Vecheslav; Sergachev, Alexei

    2018-03-01

    Binary fission of 232Th and 238U induced by fast neutrons were under intent investigation in the IPPE during recent years. These measurements were performed with a twin ionization chamber with Frisch grids. Signals from the detector were digitized for further processing with a specially developed software. It results in information of kinetic energies, masses, directions and Bragg curves of registered fission fragments. Total statistics of a few million fission events were collected during each experiment. It was discovered that for several combinations of fission fragment masses their total kinetic energy was very close to total free energy of the fissioning system. The probability of such fission events for the fast neutron induced fission was found to be much higher than for spontaneous fission of 252Cf and thermal neutron induced fission of 235U. For experiments with 238U target the energy of incident neutrons were 5 MeV and 6.5 MeV. Close analysis of dependence of fission fragment distribution on compound nucleus excitation energy gave us some explanation of the phenomenon. It could be a process in highly excited compound nucleus which leads the fissioning system from the scission point into the fusion valley with high probability.

  11. Charge distribution of the 236U* fission fragments with accounting for angular momentum of the compound nuclei

    International Nuclear Information System (INIS)

    Volkov, N.G.; Emel'yanov, V.M.; Krajnov, V.P.

    1979-01-01

    In a statistical fission model calculated are charge distributions of fission fragments (CDFF) of a 236 U* nucleus and their dispersions as the functions of excitation energy and angular momentum (AM) of a compound nucleus as well as the effect of one-particle potential parameter on CDFF. The potential of two-center oscillator was choosen as the one-particle potential. The function of fissioning nucleus level density, which is necessary for calculations in the statistical approach, has been determined from one-particle spectrum. The scheme of calculations is realized with a computer. Presented are the results of calculating the dependence of a neutron gap size on nuclear temperature for various projections of total AM; CDFF for different values of E* excitation energy of AM projection and others. Calculated CDFF and experimental data were compared. Notwithstanding the availability of many parameters and a large volume of numerical calculations the model under consideration permits to describe many common regularities of heavy nucleus CDFF (experimental yields of charges, dispersion dependence on excitation energies and masses of nuclear fragments)

  12. Thermodynamical description of excited nuclei

    International Nuclear Information System (INIS)

    Bonche, P.

    1989-01-01

    In heavy ion collisions it has been possible to obtain composite systems at rather high excitation energies corresponding to temperatures of several MeV. The theoretical studies of these systems are based on concepts borrowed from thermodynamics or statistical physics, such as the temperature. In these lectures, we present the concepts of statistical physics which are involved in the physics of heavy ion as they are produced nowadays in the laboratory and also during the final stage of a supernova collapse. We do not attempt to describe the reaction mechanisms which yield such nuclear systems nor their decay by evaporation or fragmentation. We shall only study their static properties. The content of these lectures is organized in four main sections. The first one gives the basic features of statistical physics and thermodynamics necessary to understand quantum mechanics at finite temperature. In the second one, we present a study of the liquid-gas phase transition in nuclear physics. A phenomenological approach of the stability of hot nuclei follows. The microscopic point of view is proposed in the third part. Starting from the basic concepts derived in the first part, it provides a description of excited or hot nuclei which confirms the qualitative results of the second part. Furthermore it gives a full description of most properties of these nuclei as a function of temperature. Finally in the last part, a microscopic derivation of the equation of state of nuclear matter is proposed to study the collapse of a supernova core

  13. Fragmentation in central collisions of heavy systems

    International Nuclear Information System (INIS)

    Claesson, G.; Doss, K.G.R.; Ferguson, R.

    1987-01-01

    One of the goals of heavy ion reaction studies is to understand the fragmentation of hot nuclei. The LBL/GSI Plastic Ball detector system has been used to achieve a very high solid angle for detection of light and medium-heavy fragments emitted in 200 Mev/A Au + Au and Au + Fe reactions. The simultaneous measurement of almost all of the nucleons and nuclei resulting from each collision allows an estimation of the total charged particle multiplicity and hence the impact parameter. By choosing subsets of the data corresponding to a peripheral or central collision, the assumptions inherent in various models of nuclear fragmentation can be tested. 3 refs., 3 figs

  14. Hot nuclei production and deexcitation in heavy ions induced reactions on medium mass targets in the 10-84 MeV/nucleon energy domain

    International Nuclear Information System (INIS)

    Lleres, A.

    1988-01-01

    Velocity, angular distributions and total cross sections for heavy residues produced in the reactions 12 C, 14 N, 20 Ne, 40 Ar + 124 Sn have been measured in the 10-84 MeV/nucleon incident energy range using catchers technique in association with off-line gamma-activity spectroscopy. The observed reaction products are interpreted as evaporation residues from equilibrated systems formed by complete or incomplete fusion of the projectile and target nuclei. From the velocities and residual masses measured at forward angles, the linear momentum transfers and excitation energies associated with the intermediate systems are estimated using simple fusion-evaporation models and are next compared to the predictions of the preequilibrium and Fermi jets models. Energy, angular, charge and charge correlation distributions for intermediate mass fragments emitted in the reaction 32 S + nat Ag at 30 MeV/nucleon were also measured using gaseous and silicon detectors. The energy and angular distributions indicate that both equilibrated and non-equilibrated emitting sources are present. The equilibrium emission is attributed to the deexcitation of systems produced by incomplete fusion of the projectile and target nuclei. The charge correlation distributions are consistent with an asymmetric fission decay process. The linear momentum transfer and excitation energy associated with the equilibrated source are estimated using a simple fusion-fission model [fr

  15. THE AKARI 2.5-5.0 μm SPECTRAL ATLAS OF TYPE-1 ACTIVE GALACTIC NUCLEI: BLACK HOLE MASS ESTIMATOR, LINE RATIO, AND HOT DUST TEMPERATURE

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dohyeong; Im, Myungshin; Kim, Ji Hoon; Jun, Hyunsung David; Lee, Seong-Kook [Center for the Exploration of the Origin of the Universe (CEOU), Astronomy Program, Department of Physics and Astronomy, Seoul National University, Shillim-Dong, Kwanak-Gu, Seoul 151-742 (Korea, Republic of); Woo, Jong-Hak; Lee, Hyung Mok; Lee, Myung Gyoon [Astronomy Program, Department of Physics and Astronomy, Seoul National University, Shillim-Dong, Kwanak-Gu, Seoul 151-742 (Korea, Republic of); Nakagawa, Takao; Matsuhara, Hideo; Wada, Takehiko; Takagi, Toshinobu [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa 252-5210 (Japan); Oyabu, Shinki [Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602 (Japan); Ohyama, Youichi, E-mail: dohyeong@astro.snu.ac.kr, E-mail: mim@astro.snu.ac.kr [Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, Taipei 106, Taiwan (China)

    2015-01-01

    We present 2.5-5.0 μm spectra of 83 nearby (0.002 < z < 0.48) and bright (K < 14 mag) type-1 active galactic nuclei (AGNs) taken with the Infrared Camera on board AKARI. The 2.5-5.0 μm spectral region contains emission lines such as Brβ (2.63 μm), Brα (4.05 μm), and polycyclic aromatic hydrocarbons (3.3 μm), which can be used for studying the black hole (BH) masses and star formation activity in the host galaxies of AGNs. The spectral region also suffers less dust extinction than in the ultra violet (UV) or optical wavelengths, which may provide an unobscured view of dusty AGNs. Our sample is selected from bright quasar surveys of Palomar-Green and SNUQSO, and AGNs with reverberation-mapped BH masses from Peterson et al. Using 11 AGNs with reliable detection of Brackett lines, we derive the Brackett-line-based BH mass estimators. We also find that the observed Brackett line ratios can be explained with the commonly adopted physical conditions of the broad line region. Moreover, we fit the hot and warm dust components of the dust torus by adding photometric data of SDSS, 2MASS, WISE, and ISO to the AKARI spectra, finding hot and warm dust temperatures of ∼1100 K and ∼220 K, respectively, rather than the commonly cited hot dust temperature of 1500 K.

  16. Land Use Change and Agricultural Land Fragmentation due to Anthropogenic Activities in an Hot Spot Area: A Case Study for Thrace Region of Turkey

    Science.gov (United States)

    Altürk, Bahadır; Konukcu, Fatih

    2017-04-01

    Agricultural lands that supply food, energy and ecosystem services for human life have been lost due to anthropogenic activities such as construction of roads, urban and industry areas. The significant reasons for the increase of artificial surfaces were poorly planned economic decisions by the government and internal migration due to this poorly planning. Unplanned urban sprawl also give rise to land fragmentation. Fragmentation of agricultural land affects both the agricultural production capacity and rural sustainable employment. In this study: i) Land use changes between 1990-2014 period were assessed using remotely sensed data and ii) Spatial and temporal agricultural land fragmentation were investigated using landscape pattern indice (effective mesh size), Morphological Spatial Pattern Analysis (MSPA) and Entropy method for 25 years period. The selected"hot spot" study area is located on east Thrace region of Turkey, being the service and industrial development zone where agricultural activities, water resources and natural habitat have been damaged due to rapid urban and industrial development for about 25 years. The results showed that agricultural lands decreased 6.44%, urban areas increased 111.68% and industry areas increased 251.19% during this 25 years period. Additionally, fragmentation analyses demonstrated that core agricultural areas sharply decreased and relative fragmentation (effective mesh size) increased from 50.68% to 56.77% during 1990 and 2014.

  17. RADIO ACTIVE GALAXY NUCLEI IN GALAXY CLUSTERS: HEATING HOT ATMOSPHERES AND DRIVING SUPERMASSIVE BLACK HOLE GROWTH OVER COSMIC TIME

    Energy Technology Data Exchange (ETDEWEB)

    Ma, C.-J.; McNamara, B. R. [Department of Physics and Astronomy, University of Waterloo, 200 University Ave. W., Waterloo, Ontario N2L 3G1 (Canada); Nulsen, P. E. J. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138-1516 (United States)

    2013-01-20

    We estimate the average radio active galactic nucleus (AGN, mechanical) power deposited into the hot atmospheres of galaxy clusters over more than three quarters of the age of the Universe. Our sample was drawn from eight major X-ray cluster surveys and includes 685 clusters in the redshift range 0.1 < z < 0.6 that overlap the area covered by the NRAO VLA Sky Survey (NVSS). The radio-AGN mechanical power was estimated from the radio luminosity of central NVSS sources, using the relation of Cavagnolo et al. that is based on mechanical powers determined from the enthalpies of X-ray cavities. We find only a weak correlation between radio luminosity and cluster X-ray luminosity, although the most powerful radio sources reside in luminous clusters. The average AGN mechanical power of 3 Multiplication-Sign 10{sup 44} erg s{sup -1} exceeds the X-ray luminosity of 44% of the clusters, indicating that the accumulation of radio-AGN energy is significant in these clusters. Integrating the AGN mechanical power to redshift z = 2.0, using simple models for its evolution and disregarding the hierarchical growth of clusters, we find that the AGN energy accumulated per particle in low luminosity X-ray clusters exceeds 1 keV per particle. This result represents a conservative lower limit to the accumulated thermal energy. The estimate is comparable to the level of energy needed to 'preheat' clusters, indicating that continual outbursts from radio-AGN are a significant source of gas energy in hot atmospheres. Assuming an average mass conversion efficiency of {eta} = 0.1, our result implies that the supermassive black holes that released this energy did so by accreting an average of {approx}10{sup 9} M {sub Sun} over time, which is comparable to the level of growth expected during the quasar era.

  18. Properties and decay modes of hot nuclei produced in the reaction: {sup 36}Ar on {sup 58}Ni and detected with INDRA device; Proprietes et modes de desexcitation des noyaux chauds observes dans la reaction {sup 36}Ar sur {sup 58}Ni avec le detecteur INDRA

    Energy Technology Data Exchange (ETDEWEB)

    Nalpas, L [CEA Centre d` Etudes de Saclay, 91 - Gif-sur-Yvette (France). Dept. d` Astrophysique, de la Physique des Particules, de la Physique Nucleaire et de l` Instrumentation Associee; [Paris-11 Univ., 91 - Orsay (France)

    1997-01-01

    Hot nuclei are formed in heavy ion collisions covering the Fermi energy domain. According to the excitation energy deposited into these nuclei, several de-excitation processes can be observed, in particular the emission of complex fragments (Z {>=} 3) which remains poorly understood. The GANIL facility offers the possibility to cover the excitation function for the Ar on Ni reaction over a broad energy range from 32 to 95 MeV/u where the hot nuclei evolve from classical `evaporation` to complete `vaporization` into light particles (neutrons, isotopes of H, He). The study of reaction mechanisms shows that from peripheral to central collisions the total cross section is dominated by binary dissipative collisions. Both partners coming from well-characterized events with the INDRA detector are reconstructed using the `Minimum Spanning Tree` method. Thus excitation energy up to 20 MeV/A are reached in the most violent collisions at the highest bombarding energy. The deposited energy is not shared in the mass ratio between the quasi-projectile and the quasi-target, the quasi-projectile being hotter. For total excitation energies ranging roughly from 2 to 8 MeV/A, the proportion of `multifragmentation` events increases to reach a plateau at about 10 MeV/A due to the rising probability to have complete `vaporization` of the system above 8 MeV/A. The steady increase of the temperature extracted from the double isotopic He-Li ratios with excitation energy for the quasi-projectile suggests a progressive evolution of the de-excitation processes as predicted by statistical models. No signal of first order liquid-gas phase transition is seen in our data. (author) 124 refs.

  19. Active Galactic Nuclei Feedback and the Origin and Fate of the Hot Gas in Early-type Galaxies

    Science.gov (United States)

    Pellegrini, Silvia; Ciotti, Luca; Negri, Andrea; Ostriker, Jeremiah P.

    2018-04-01

    A recent determination of the relationships between the X-ray luminosity of the ISM (L X) and the stellar and total mass for a sample of nearby early-type galaxies (ETGs) is used to investigate the origin of the hot gas, via a comparison with the results of hydrodynamical simulations of the ISM evolution for a large set of isolated ETGs. After the epoch of major galaxy formation (after z ≃ 2), the ISM is replenished by stellar mass losses and SN ejecta, at the rate predicted by stellar evolution, and is depleted by star formation; it is heated by the thermalization of stellar motions, SNe explosions, and the mechanical (from winds) and radiative AGN feedback. The models agree well with the observed relations, even for the largely different L X values at the same mass, thanks to the sensitivity of the gas flow to many galaxy properties; this holds for models including AGN feedback, and those without. Therefore, the mass input from the stellar population is able to account for a major part of the observed L X; and AGN feedback, while very important to maintain massive ETGs in a time-averaged quasi-steady state, keeping low star formation and the black hole mass, does not dramatically alter the gas content originating in stellar recycled material. These conclusions are based on theoretical predictions for the stellar population contributions in mass and energy, and on a self-consistent modeling of AGN feedback.

  20. Explosion-evaporation model for fragment production in intermediate-energy nuclear collisions

    International Nuclear Information System (INIS)

    Fai, G.; Randrup, J.

    1981-01-01

    Nuclear collisions at intermediate energies may create transient systems of hot nuclear matter that decay into many nuclear fragments. The disassembly of such a nuclear fireball is described as a two-stage process. In the primary explosion stage the system quickly fragments into nucleons and composite nuclei according to the available phase space. The explosion produces excited nuclei with half-lives longer than the time associated with the breakup. In the secondary evaporation stage, these nuclei decay, first by sequential emission of light particles (neutrons, protons, alphas), later by electromagnetic radiation. The secondary stage in general changes the relative abundancies of the various fragment species. This general feature makes it essential to take account of the composite fragments before using d/p as a measure of the entropy of the initial source. The formation of unbound nuclei at the explosion stage also has the desirable effect of enhancing the final abundancies of particularly stable nuclei, e.g., 4 He. For neutron-excessive sources the presence of composite nuclei amplifies the ratio of observed neutrons and protons; this effect persists for heavier mirror systems. Predictions of the model are qualitatively compared to available experimental data. The model offers a convenient way to augment existing dynamical models, such as intra-nuclear cascade and nuclear fluid dynamics, to yield actual nuclear fragments rather than merely matter distributions

  1. Studies of exotic nuclei

    International Nuclear Information System (INIS)

    Angelique, J.C.; Orr, N.A.

    1997-01-01

    The study of the nuclei far off stability valley is of much interest for testing the nuclear models established for the stable nuclei but also for astrophysics to understand the nucleosynthesis. Experiments aim to measure the mass and lifetime, to build the decay schemes and also to study the structure and the properties of these nuclei. The radioactive beam group focused its research on light neutron-rich nuclei having a halo neutron structure. Mass measurements in N ∼ Z nuclei namely in A ∼ 60-80 proton-rich nuclei, important for understanding the rp process, are mentioned, as well as in nuclei in the 100 Sn region. In the newly obtained 26 O and 28 O nuclei the lifetimes, the probabilities of emission of one for more neutrons were determined. The data analysis has permitted to determine also for the first time the lifetimes of 27,29 F and 30 Ne. Studies of nuclei in the 100 Sn region, near the proton drip line in the ground and isomeric states are now under way. The spectroscopy (energy levels, gamma emissions, etc.) of the neutron-rich nuclei produced by the 36 S fragmentation has been carried out in 31 Ne, 17 B and 29 F. Studies by Coulomb excitation of the 2 + excited states and associated probability B (E2) in O, Ne, Ni and Zn are now analysed

  2. Anomalous nuclear fragments

    International Nuclear Information System (INIS)

    Karmanov, V.A.

    1983-01-01

    Experimental data are given, the status of anomalon problem is discussed, theoretical approaches to this problem are outlined. Anomalons are exotic objects formed following fragmentation of nuclei-targets under the effect of nuclei - a beam at the energy of several GeV/nucleon. These nuclear fragments have an anomalously large cross section of interaction and respectively, small free path, considerably shorter than primary nuclei have. The experimental daa are obtained in accelerators following irradiation of nuclear emulsions by 16 O, 56 Fe, 40 Ar beams, as well as propane by 12 C beams. The experimental data testify to dependence of fragment free path on the distance L from the point of the fragment formation. A decrease in the fragment free path is established more reliably than its dependence on L. The problem of the anomalon existence cannot be yet considered resolved. Theoretical models suggested for explanation of anomalously large cross sections of nuclear fragment interaction are variable and rather speculative

  3. Yields of nuclear fragments in the interactions of carbon nuclei with a beryllium target at a projectile energy of 0.6 GeV per nucleon

    Energy Technology Data Exchange (ETDEWEB)

    Abramov, B. M.; Alexeev, P. N.; Borodin, Yu. A.; Bulychjov, S. A. [National Research Center Kurchatov Institute, Institute for Theoretical and Experimental Physics (Russian Federation); Gudima, K. K. [Academy of Sciences of Moldova, Institute of Applied Physics (Moldova, Republic of); Dukhovskoy, I. A.; Krutenkova, A. P., E-mail: anna.krutenkova@itep.ru; Kulikov, V. V.; Martemianov, M. A.; Matsyuk, M. A. [National Research Center Kurchatov Institute, Institute for Theoretical and Experimental Physics (Russian Federation); Mashnik, S. G. [Los Alamos National Laboratory (United States); Turdakina, E. N.; Khanov, A. I. [National Research Center Kurchatov Institute, Institute for Theoretical and Experimental Physics (Russian Federation)

    2016-09-15

    The yields of long-lived nuclear fragments at an angle of 3.5° that originate fromthe fragmentation of carbon ions with an energy of T{sub 0} = 0.6 GeV per nucleon on a berylliumtarget were measured in the FRAGMexperiment at the ITEP TWA heavy-ion accelerator. The momentum spectra of these fragments cover both the fragmentation-maximum region and the cumulative region. The respective differential cross sections change by about five orders of magnitude. The momentum distributions of fragments in the laboratory frame and their kinetic-energy distributions in the rest frame of the fragmenting nucleus are used to test the predictions of four models of ion–ion interactions: BC, INCL++, LAQGSM03.03, and QMD.

  4. Fission dynamics of hot nuclei

    Indian Academy of Sciences (India)

    2014-04-05

    Apr 5, 2014 ... across the fission barrier is very small or in other words, the fission barrier is much ... of this shape evolution, the gross features of the fissioning nucleus can be described ..... [7] Y Abe, C Gregoire and H Delagrange, J. Phys.

  5. Nuclei transmutation by collisions with fast hadrons and nuclei

    International Nuclear Information System (INIS)

    Strugalski, Z.; Strugalska-Gola, E.; Drzymala, A.

    1998-01-01

    Atomic nuclei change their mass- and charge-numbers if bombarded by fast hadrons and nuclei; the transmutation appears as a complicated process. It proceeds in a definite way - through a few stages or phases. Adequate identification of the nucleons and light nuclear fragments emitted and evaporated in a hadron-nucleus or nucleus-nucleus collisions and in the collision-induced intranuclear reactions allows one to estimate quantitatively the nuclei transmutations in the various stages (phases) of the process

  6. Estimation of cross sections of hypotetical 8n0, 10He2, 13Li3 nuclei production in the framework of fast fragmentation model

    International Nuclear Information System (INIS)

    Lozhkin, O.V.; Oplavin, V.S.; Yakovlev, Yu.P.

    1983-01-01

    The possibilities of search for 8 n 0 , 10 He 2 , 13 Li 3 nuclides in the products of nuclear fragmentation under the action of high energy particles are analysed. Conclusions have been drawn that: available experimental data on determination of the upper boundary of a cross section of 8 n 0 fragments production exclude an existence of this nuclide in the form ''usual'' nuclear system; available experimental estimations of cross sections of 10 He and 13 Li production among fragmentation products are, for the present, insufficient to solve a problem of 13 Li nucleus existence in a bound state but testify on 10 He nucleus nuclear instability; serious model estimations of have functions and nuclide binding energy are necessary

  7. Study of Particle Production and Nuclear Fragmentation in Collisions of $^{16}$O Beams with Emulsion Nuclei at 13-200 A GeV

    CERN Multimedia

    2002-01-01

    .SK 2\\\\ \\\\ The aim of the experiment is to study, on an event by event basis, multiplicities of produced charged particles, pseudo-rapidity density distributions globally and in selected regions of pseudo-rapidity, density fluctuations, multiplicity and angular distributions of nuclear fragments and recoiling protons (30-400~A~MeV) and cross sections for production and interation of light and medium (Z=2-8) projectile fragments. \\\\ \\\\ The detectors are emulsion chambers as well as conventional emulsion stacks. The emulsion chambers consist of several layers of a plastic substrate, each coated with nuclear emulsion on both sides. Since the best measurement accuracy is obtained for the particles with the smallest emission angles, this design is especially suited for the pseudo-rapidity determination. The emulsion stacks, of both high and low sensitivity, have been exposed in the conventional way, with the beam parallel to the emulsion sheets. These stacks are used to study the fragmentation of the interaction n...

  8. Pseudomagic nuclei

    International Nuclear Information System (INIS)

    Scharff-Goldhaber, G.

    1979-01-01

    It was shown previously that, below a critical angular momentum, yrast bands of nonmagic nuclei are well described by the two-parameter variable moment of inertia model. Some striking exceptions to this rule are found in nuclei which have the same mass number as doubly magic nuclei but possess either one (or two) proton pairs beyond a magic number and one (or two) neutron hole pairs, or vice versa. Yrast bands in these pseudomagic nuclei resemble those in magic nuclei. 17 references

  9. Cumulation of light nuclei

    International Nuclear Information System (INIS)

    Baldin, A.M.; Bondarev, V.K.; Golovanov, L.B.

    1977-01-01

    Limit fragmentation of light nuclei (deuterium, helium) bombarded with 8,6 GeV/c protons was investigated. Fragments (pions, protons and deuterons) were detected within the emission angle 50-150 deg with regard to primary protons and within the pulse range 150-180 MeV/c. By the kinematics of collision of a primary proton with a target at rest the fragments observed correspond to a target mass upto 3 GeV. Thus, the data obtained correspond to teh cumulation upto the third order

  10. Multiplicity distributions of projectile fragments in interactions of nuclei with emulsion at 4.1-4.5 A GeV/c

    International Nuclear Information System (INIS)

    Fakhraddin, S; Rahim, Magda A

    2008-01-01

    The results of our systematic studies of projectile fragments (PFs) multiplicity distributions in interactions of 4 He, 12 C, 16 O, 22 Ne and 28 Si with emulsion at 4.1-4.5 A GeV/c are presented in this paper. The mean values for the three different multiplicities of PFs at nearly the same energy are given. The dependence of these mean values on the projectile mass number A p , as well as the dependence of the PFs on target groups (H, CNO and AgBr), has been investigated

  11. Multiplicity distributions of projectile fragments in interactions of nuclei with emulsion at 4.1-4.5 A GeV/c

    Energy Technology Data Exchange (ETDEWEB)

    Fakhraddin, S; Rahim, Magda A [Physics Department, Faculty of Science, Sana' a University, Republic of Yemen (Yemen)], E-mail: sakinafa1@hotmail.com, E-mail: dr.magda2006@hotmail.com

    2008-07-15

    The results of our systematic studies of projectile fragments (PFs) multiplicity distributions in interactions of {sup 4}He, {sup 12}C, {sup 16}O, {sup 22}Ne and {sup 28}Si with emulsion at 4.1-4.5 A GeV/c are presented in this paper. The mean values for the three different multiplicities of PFs at nearly the same energy are given. The dependence of these mean values on the projectile mass number A{sub p}, as well as the dependence of the PFs on target groups (H, CNO and AgBr), has been investigated.

  12. On the distribution of quarks in nuclei

    International Nuclear Information System (INIS)

    Baldin, A.M.; Panebrattsev, V.S.; Stavinskij, V.S.

    1984-01-01

    On the basis of the data on cumulative proton, deuteron and nuclear fragment production in hadr on-nucleon reactions and deep inelastic muon-nucleon scattering quark distributions in light, intemediate and heavy nuclei have been investigated. Conditions of limiting fragmentation of hadrons and nuclei in the studied processes have been investigated to obtain quark-parton structure functions (Gs 2 ) of the studied hadrons or nuclei. Invariant differential cross sections of π + , π - , K + meson production on aluminium, deuterium and lead nuclei and their dependence on scale variable at the transverse momentum value Psub(T) approximately 0 have been obtained. Properties of structure functions G 2 and behaviour of different nuclei differential cross sections of limiting fragmentation have been investigated. It is concluded that considered regularities testify to the presence of multiquark states in nuclei, different by its structure from nUcleons

  13. Exotic nuclei

    International Nuclear Information System (INIS)

    Villari, A.C.C.

    1990-01-01

    The actual tendencies to study exotic nuclei; applications of exotic nuclei beams in material study and medicine; recent results obtained by GANIL and Berkeley Laboratories of measurements of binding energy and radii of light nuclei; the future experiences to be carry out in several international laboratories and; proposal of studies in Brazil using Pelletron-USP accelerator and the LINAC superconductor accelerator, in construction in the same laboratory, are presented. (M.C.K.)

  14. Spinodal decomposition of atomic nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Chomaz, P. [Grand Accelerateur National d`Ions Lourds (GANIL), 14 - Caen (France); Colonna, M.; Guarnera, A. [Grand Accelerateur National d`Ions Lourds (GANIL), 14 - Caen (France)]|[LNS, Catania (Italy)

    1996-12-31

    Multifragmentation of atomic nuclei is discussed. It is shown that this description of the dynamics of first order phase transitions in infinite and finite system is now partially achieved. An important conclusion is that in some specific cases well-defined collective motions were initiating the self-organisation of the unstable matter in fragments. In the case of finite systems the possible signals kept from this early fragmentation stage can inform on the possible occurrence of a liquid-gas phase transition in nuclei. (K.A.). 21 refs.

  15. Spinodal decomposition of atomic nuclei

    International Nuclear Information System (INIS)

    Chomaz, P.; Colonna, M.; Guarnera, A.

    1996-01-01

    Multifragmentation of atomic nuclei is discussed. It is shown that this description of the dynamics of first order phase transitions in infinite and finite system is now partially achieved. An important conclusion is that in some specific cases well-defined collective motions were initiating the self-organisation of the unstable matter in fragments. In the case of finite systems the possible signals kept from this early fragmentation stage can inform on the possible occurrence of a liquid-gas phase transition in nuclei. (K.A.)

  16. First Isochronous Time-of-Flight Mass Measurements of Short-Lived Projectile Fragments in the ESR

    International Nuclear Information System (INIS)

    Stadlmann, J.; Geissel, H.; Hausmann, M.; Nolden, F.; Radon, T.; Schatz, H.; Scheidenberger, C.; Attallah, F.; Beckert, K.; Bosch, F.; Falch, M.; Franczak, B.; Franzke, B.; Kerscher, Th.; Klepper, O.; Kluge, H.J.; Kozhuharov, C.; Loebner, K.E.G.; Muenzenberg, G.; Novikov, Yu.N.; Steck, M.; Sun, Z.; Suemmerer, K.; Weick, H.; Wollnik, H.

    2000-01-01

    A new method for precise mass measurements of short-lived hot nuclei is presented. These nuclei were produced via projectile fragmentation, separated with the FRS and injected into the storage ring ESR being operated in the isochronous mode. The revolution time of the ions is measured with a time-of-flight detector sensitive to single particles. This new method allows access to exotic nuclei with half-lives in the microsecond region. First results from this novel method obtained with measurements on neutron-deficient fragments of a chromium primary beam with half-lives down to 50 ms are reported. A precision of deltam/m ≤ 5 · 10 -6 has been achieved

  17. Radii of nuclei off stability

    International Nuclear Information System (INIS)

    Sugimoto, Kenzo

    1982-01-01

    An experiment is proposed to determine systematically the radii of the nuclei produced through the projectile fragmentation process in high energy heavy-ion collision. The measurement of total reaction cross section using the projectile fragments of a single nuclide on a target give information about nuclear radii. The production cross section of the fragments is appreciable for many nuclides. Therefore, it is possible to map systematically the reaction radii of the nuclei which can be produced as the projectile fragments. In an experiment using the projectile fragments as the incident beam, the cross section can be expressed as a function of the radii of a projectile and a target. An experiment with He-8 produced by the fragmentation of C-12 is proposed. The He-8 has four neutrons in the p-3/2 orbit outside the He-4 core. Proton and neutron distributions for He isotopes were calculated on the basis of the Hartree-Fock method. The information related to this kind of distribution can be obtained by the proposed experiment. The nuclear structure effect is seen in the nuclear radii of other unstable nuclei. The experimental examples of the isotope shift measurement and the excitation energy are presented. (Kato, T.)

  18. Nuclei at the limits of particle stability

    International Nuclear Information System (INIS)

    Mueller, A.C.

    1993-01-01

    The properties and synthesis of nuclei at the limits of particle stability are reviewed. Nuclear reactions were induced and studied by means of the 'exotic' nuclear beams, i.e. beams of radioactive drip-line nuclei. The beams are mostly generated in heavy-ion projectile fragmentation. The cases of both neutron-rich and proton-rich nuclei are discussed. (K.A.) 270 refs.; 13 figs.; 1 tab

  19. Neutron-capture reactions by stable and unstable neutron-rich nuclei and their relevance for nucleosynthesis in hot and explosive astrophysical scenarios

    International Nuclear Information System (INIS)

    Hofinger, R.

    1997-10-01

    This thesis deals on the one hand with neutron-capture reactions by carbon-, nitrogen-, oxygen- and sulfur-isotopes, and on the other hand with the two-step processes 4 He(2n, γ) 6 He and 9 Li(2n, γ) 11 Li. Some of the involved carbon-, nitrogen- and oxygen-isotopes possess neutron-halos characterized by the unexpected large radial extension of the nuclear matter density distribution. Special attention is paid to the halo properties in the calculation of the direct neutron capture cross section. For the determination of the nuclear structure, models are used, when no experimental information is available. The results for the reaction rates are compared to previously used rates. The rates obtained in this work are partly orders of magnitude higher than the previously used reaction rates. The reaction rates for the two-step processes are on the one hand calculated assuming a two-step process, on the other hand from genuine three-body models for the process of photodisintegration of the nuclei 6 He and 11 Li. It turns out that the calculations assuming a trio-step process underestimate the reaction rates by orders of magnitude. The influence of the reaction rate for the reaction 4 He(2n, γ) 6 He and the formation of 12 C is examined in a nuclear reaction network under conditions which are typical for the α- process in supernovae of type II. It turns out that under these conditions the influence of the reaction 4 He(2n, γ) 6 He is negligible on the formation of 12 C. (author)

  20. Reentrainment of radioactive nuclei from filters

    International Nuclear Information System (INIS)

    Dincklage, R.-D. von

    1982-01-01

    The possible relevance of atomic phenomena for the reentrainment of radioactive nuclei is discussed. The considerations are based on the coulombic fragmentation mechanism. Nuclei of potential interest in reprocessing technology are identified. Future experiments have been shown to be of definite need in this field. (author)

  1. Anomalous carbon nuclei

    International Nuclear Information System (INIS)

    Gasparian, A.P.

    1984-01-01

    Results are presented from a bubble chamber experiment to search for anomalous mean free path (MFP) phenomena for secondary multicharged fragments (Zsub(f)=5 and 6) of the beam carbon nucleus at 4.2 GeV/c per nucleon. A total of 50000 primary interactions of carbon with propane (C 3 H 8 ) were created. Approximately 6000 beam tragments with charges Zsub(f)=5 and 6 were analyzed in detail to find out an anomalous decrease of MFP. The anomaly is observed only for secondary 12 C nuclei

  2. Characterization of Three Druggable Hot-Spots in the Aurora-A/TPX2 Interaction Using Biochemical, Biophysical, and Fragment-Based Approaches

    Czech Academy of Sciences Publication Activity Database

    McIntyre, P. J.; Collins, P. M.; Vrzal, Lukáš; Birchall, K.; Arnold, L. H.; Mpamhanga, C.; Coombs, P. J.; Burgess, S. G.; Richards, M. W.; Winter, A.; Veverka, Václav; von Delft, F.; Merritt, A.; Bayliss, R.

    2017-01-01

    Roč. 12, č. 11 (2017), s. 2906-2914 ISSN 1554-8929 R&D Projects: GA MŠk(CZ) LK11205; GA MŠk(CZ) LO1304 Institutional support: RVO:61388963 Keywords : fragment-based drug discovery * structural biology * inhibition Subject RIV: CE - Biochemistry OBOR OECD: Biochemistry and molecular biology Impact factor: 4.995, year: 2016

  3. Azimuthal Anisotropies in Nuclear Fragmentation

    International Nuclear Information System (INIS)

    Dabrowska, A.; Szarska, M.; Trzupek, A.; Wolter, W.; Wosiek, B.

    2002-01-01

    The directed and elliptic flow of fragments emitted from the excited projectile nuclei has been observed for 158 AGeV Pb collisions with the lead and plastic targets. For comparison the flow analysis has been performed for 10.6 AGeV Au collisions with the emulsion target. The strong directed flow of heaviest fragments is found. Light fragments exhibit directed flow opposite to that of heavy fragments. The elliptic flow for all multiply charged fragments is positive and increases with the charge of the fragment. The observed flow patterns in the fragmentation of the projectile nucleus are practically independent of the mass of the target nucleus and the collision energy. Emission of fragments in nuclear multifragmentation shows similar, although weaker, flow effects. (author)

  4. Anomalous component of absorption function of relativistic fragments produced in interactions of magnesium nuclei with plexiglas at 4. 5A GeV/c momentum. Anomal'naya komponenta funktsii pogloshcheniya relyativistskikh fragmentov, obrazovannykh vo vzaimodejstviyakh yader magniya c pleksiglasom pri impul'se 4. 5A GeV/c

    Energy Technology Data Exchange (ETDEWEB)

    Karev, A G; Morozov, B A; Petukhov, Yu P; Povtorejko, A A; Sukhanov, A Yu [Joint Inst. for Nuclear Research, Dubna (USSR)

    1989-01-01

    Analysis of the Cherenkov spectrometer results on the fragmentation of the magnesium nuclei with momenta 4.5A GeV/c interacting with plexiglas show the presence of a short-range component in the fragment absorption function. For fragments with Z=6-10 (Z is the charge) the mean free paths in plexiglas for normal and anomalous component are estimated to be {lambda}{sub n}=141.7 {plus minus} 1.9 mm and {lambda}{sub a}=1.9 {plus minus} 0.8 mm. The anomalous component admixture at fixed {lambda}{sub a}=2 mm is {alpha}=0.084 {plus minus} 0.027. The parameter estimates are stable for various criteria applied to selecting the events.

  5. Superdeformed nuclei

    International Nuclear Information System (INIS)

    Janssens, R.V.F.; Khoo, T.L.

    1991-01-01

    Superdeformation was first proposed some twenty years ago to explain the fission isomers observed in some actinide nuclei. It was later realized that superdeformed shapes can occur at high angular momentum in lighter nuclei. The interest in the mechanisms responsible for these exotic shapes has increased enormously with the discovery of a superdeformed band of nineteen discrete lines in 152 Dy (8). At about the same time, evidence for highly deformed nuclei (axis ratio 3:2) was also reported near 132 Ce(9). Striking properties emerged from the first experiments, such as the essentially constant energy spacing between transitions (picket-fence spectra), the unexpectedly strong population of superdeformed bands at high spins, and the apparent lack of a link between the superdeformed states and the yrast levels. These findings were reviewed by Nolan and Twin. The present article follows upon their work and discusses the wealth of information that has since become available. This includes the discovery of a new island of superdeformation near A = 190, the detailed spectroscopy of ground and excited bands in the superdeformed well near A = 150 and A = 190, the surprising occurrence of superdeformed bands with identical transition energies in nuclei differing by one or two mass units, and the improved understanding of mechanisms responsible for the feeding into and the decay out of the superdeformed states

  6. Fission fragment spins and spectroscopy

    International Nuclear Information System (INIS)

    Durell, J.L.

    1988-01-01

    Prompt γ-ray coincidence experiments have been carried out on γ-rays emitted from post-neutron emission fission fragments produced by the aup 19F + 197 Au and 18 O + 232 Th reactions. Decay schemes have been established for even-even nuclei ranging from 78 Se to 148 Nd. Many new states with spin up to ∼ 12h have been observed. Apart from providing a wealth of new information on the spectroscopy of neutron-rich nuclei, the data have been analyzed to determine the average spin of primary fission fragments as a function of fragment mass. The results suggest that the fragment spins are determined by the temperature and shape of the primary fragments at or near to scission

  7. Physics of projectile fragments

    International Nuclear Information System (INIS)

    Minamisono, Tadanori

    1982-01-01

    This is a study report on the polarization phenomena of the projectile fragments produced by heavy ion reactions, and the beta decay of fragments. The experimental project by using heavy ions with the energy from 50 MeV/amu to 250 MeV/amu was designed. Construction of an angle-dispersion spectrograph for projectile fragments was proposed. This is a two-stage spectrograph. The first stage is a QQDQQ type separator, and the second stage is QDQD type. Estimation shows that Co-66 may be separated from the nuclei with mass of 65 and 67. The orientation of fragments can be measured by detecting beta-ray. The apparatus consists of a uniform field magnet, an energy absorber, a stopper, a RF coil and a beta-ray hodoscope. This system can be used for not only this purpose but also for the measurement of hyperfine structure. (Kato, T.)

  8. Decay and fission of the oriented nuclei

    CERN Document Server

    Kadmenskij, S G

    2002-01-01

    The fragment angular distributions for binary decay of oriented spherical and deformed nuclei with taking into account the correct transformational properties of wave functions under time inversion have been investigated. It has been shown that for description of fragment angular distributions the adiabatic approximation for collective rotational nuclear degrees of freedom is not correct. It has been demonstrated that this approximation is valid for description of spontaneous and induced low-energy nuclear fission. The dependence of partial fission widths on the orientation of the internal axes spins, projections of spins, and relative angular moments of fission fragments has been analyzed. It has been shown that the adiabatic approximation results in coherent interference of wave functions of fragments relative movement. This interference forms fragments the universal angular distributions of fission fragments for oriented nuclei. For these distributions the deviations from A. Bohr's formula have been invest...

  9. High energy collisions of nuclei: experiments

    International Nuclear Information System (INIS)

    Heckman, H.H.

    1977-09-01

    Heavy-ion nuclear reactions with projectile energies up to 2.1 GeV/A are reviewed. The concept of ''rapidity'' is elucidated, and the reactions discussed are divided into sections dealing with target fragmentation, projectile fragmentation, and the intermediate region, with emphasis on the production of light nuclei in high-energy heavy-ion collisions. Target fragmentation experiments using nuclear emulsion and AgCl visual track detectors are also summarized. 18 figures

  10. Fission fragment angular momentum

    International Nuclear Information System (INIS)

    Frenne, D. De

    1991-01-01

    Most of the energy released in fission is converted into translational kinetic energy of the fragments. The remaining excitation energy will be distributed among neutrons and gammas. An important parameter characterizing the scission configuration is the primary angular momentum of the nascent fragments. Neutron emission is not expected to decrease the spin of the fragments by more than one unit of angular momentum and is as such of less importance in the determination of the initial fragment spins. Gamma emission is a suitable tool in studying initial fragment spins because the emission time, number, energy, and multipolarity of the gammas strongly depend on the value of the primary angular momentum. The main conclusions of experiments on gamma emission were that the initial angular momentum of the fragments is large compared to the ground state spin and oriented perpendicular to the fission axis. Most of the recent information concerning initial fragment spin distributions comes from the measurement of isomeric ratios for isomeric pairs produced in fission. Although in nearly every mass chain isomers are known, only a small number are suitable for initial fission fragment spin studies. Yield and half-life considerations strongly limit the number of candidates. This has the advantage that the behavior of a specific isomeric pair can be investigated for a number of fissioning systems at different excitation energies of the fragments and fissioning nuclei. Because most of the recent information on primary angular momenta comes from measurements of isomeric ratios, the global deexcitation process of the fragments and the calculation of the initial fragment spin distribution from measured isomeric ratios are discussed here. The most important results on primary angular momentum determinations are reviewed and some theoretical approaches are given. 45 refs., 7 figs., 2 tabs

  11. Colliding nuclei

    International Nuclear Information System (INIS)

    Balian, Roger; Remaud, Bernard; Suraud, E.; Durand, Dominique; Tamain, Bernard; Gobbi, A.; Cugnon, J.; Drapier, Olivier; Govaerts, Jan; Prieels, Rene

    1995-09-01

    This 14. international school Joliot-Curie of nuclear physic deals with nuclei in collision at high energy. Nine lectures are included in the proceedings of this summer school: 1 - From statistical mechanics outside equilibrium to transport equations (Balian, R.); 2 - Modeling of heavy ions reactions (Remaud, B.); 3 - Kinetic equations in heavy ions physics (Suraud, E.); 4 - Colliding nuclei near the Fermi energy (Durand, D.; Tamain, B.); 5 - From the Fermi to the relativistic energy domain: which observable? For which physics? (Gobbi, A.); 6 - Collisions at relativistic and ultra relativistic energies, Theoretical aspects (Cugnon, J.); 7 - Quark-gluon plasma: experimental signatures (Drapier, O.); 8 - Electroweak interaction: a window on physics beyond the standard model (Govaerts, J.); 9 - Symmetry tests in β nuclear process: polarization techniques (Prieels, R.)

  12. Hot rotating fp shell Fe isotopes near proton drip line

    International Nuclear Information System (INIS)

    Aggarwal, Mamta

    2003-01-01

    F p shell 44-58 Fe nuclei have been investigated in highly excited state using the statistical theory of hot rotating nucleus. Effects of thermal and rotational excitation at drip line nuclei are studied

  13. A study of the disintegration of highly excited nuclei with the Vlasov-Uehling-Uhlenbeck equation

    International Nuclear Information System (INIS)

    Vinet, L.; Gregoire, C.; Schuck, P.; Remaud, B.; Sebille, F.

    1987-01-01

    The disintegration of hot and/or compressed nuclei is studied using (i) the Vlasov equation (VE) with imposed spherical symmetry, (ii) the VE in three dimensions (3D) and (iii) the VE in three dimensions supplemented by the Uehling-Uhlenbeck collision term (VUU). We find that case (ii) is slightly more unstable with respect to disintegration compared to case (i) whereas (iii) tends to make nuclei more stable. In all cases the thermal energies (15-20 MeV per nucleon) needed to totally disintegrate a nucleus seem to be higher than those found in static and hydrodynamic calculation. On the contrary, compressional energy very much helps disintegration. Some comments on the introduction of fluctuations and corresponding fragmentation are added. (orig.)

  14. Polarization and alignment of nucleus fission fragments

    International Nuclear Information System (INIS)

    Barabanov, A.L.; Grechukhin, D.P.

    1987-01-01

    Correlation of fragment orientation with orientation axis of fissile nucleus and with n-vector f vector of fragment divergence is considered. Estimations of polarization and alignment of fission fragments of preliminarily oriented nuclei in correlation (with n-vector f recording) and integral (with n-vector f averaging) experiments were conducted. It is shown that high sensitivity of polarization and fragment alignment to the character of nucleus movement at the stage of descent from barrier to rupture point exists

  15. The Fragmentation of Heavy Nuclei by 13.8 GeV/c Protons as a Contribution to the Study of the Interaction Mechanism and Nuclear Structure; Fragmentacion de nucleos pesados por protones de 13'8 GeV/c, como contribucion al estudio del mecanismo de interaccion y estructura nuclear

    Energy Technology Data Exchange (ETDEWEB)

    Gil Perez, D.

    1967-07-01

    We present here an global study of the interaction between high- energy particles and heavy nuclei, an interaction which holds obvious interest in relation to the problems of nuclear fragmentation and which, up lo now has only been studied piecemeal. We have used three stacks of photographic emulsions which were irradiated by 13.8 GeV/c protons, 17 GeV/c negative pions and 24 GeV/c protons. All three irradiations took place in a 180 K.G. magnetic field using CERN beams. (Author) 20 refs.

  16. The Fragmentation of Heavy Nuclei by 13.8 GeV/c Protons as a Contribution to the Study of the Interaction Mechanism and Nuclear Structure; Fragmentacion de nucleos pesados por protones de 13'8 GeV/c, como contribucion al estudio del mecanismo de interaccion y estructura nuclear

    Energy Technology Data Exchange (ETDEWEB)

    Gil Perez, D

    1967-07-01

    We present here an global study of the interaction between high- energy particles and heavy nuclei, an interaction which holds obvious interest in relation to the problems of nuclear fragmentation and which, up lo now has only been studied piecemeal. We have used three stacks of photographic emulsions which were irradiated by 13.8 GeV/c protons, 17 GeV/c negative pions and 24 GeV/c protons. All three irradiations took place in a 180 K.G. magnetic field using CERN beams. (Author) 20 refs.

  17. Viscosity: From air to hot nuclei

    Indian Academy of Sciences (India)

    In the verification of the condition for applying .... From the concept of collective theories, one of the fundamental explanations for the giant resonance ... temperature-dependent self-consistent Hartree–Fock calculations, which showed that the.

  18. Primordial nuclei

    International Nuclear Information System (INIS)

    Anon.

    1995-01-01

    The recent detection of intergalactic helium by NASA's Astro-2 mission backs up two earlier measurements by ESA and the University of California, San Diego, using instruments aboard the Hubble Space Telescope. Taken together, these results give strong evidence that this helium is primordial, confirming a key prediction of the Big Bang theory. The amount of helium the results imply could also account for some of the Universe's invisible dark matter - material which affects galactic motion but is otherwise undetectable. According to theory, helium nuclei formed at around 100 seconds after the Big Bang, but the amount of helium depended on even earlier events. Initially, protons turned into neutrons with the same probability that neutrons turned into protons. But after about one second, the Universe had cooled down enough for the weak interaction to freeze out. Neutrons continued to decay into the slightly lighter protons, whilst the opposite reaction became much more scarce. At around 100 seconds, thermonuclear fusion reactions could begin, and all the neutrons that were left became absorbed into helium nuclei, leaving the remaining protons locked up in hydrogen. The ratio of helium to hydrogen was therefore determined by events occurring when the Universe was just one second old. Standard models of primordial nucleosynthesis fix this ratio at slightly less than 2 5% by mass. All heavier elements were cooked up much later in the stars, and amount to less than 1 % of the Universe's mass. These predictions have been borne out remarkably well by observation, although proof of the primordial origins of hydrogen and helium has remained elusive until now. Big Bang nucleosynthesis goes on to estimate that primordial baryonic matter in the form of light nuclei could account for around 10% of the Universe's dark matter. All three recent measurements used the same technique of looking at distant quasars, some of the most luminous objects in the Universe, to

  19. Collective excitations in nuclei

    International Nuclear Information System (INIS)

    Chomaz, Ph.

    1998-01-01

    The properties of the nucleus cannot be reduced to the properties of its constituents: it is a complex system. The fact that many properties of the nucleus are consequences of the existence of mean-field potential is a manifestation of this complexity. In particular, the nucleons can thus self-organize in collective motions such as giant resonances. Therefore the study of this collective motions is a very good tool to understand the properties of the nucleus itself. The purpose of this article is to stress some aspects of these collective vibrations. We have studied how an ensemble of fermions as the nucleus can self-organize in collective vibrations which are behaving like a gas of bosons in weak interaction. Understanding of these phenomena remains one of the important subjects of actuality in the context of quantal systems in strong interaction. In particular, the study of the states with one or two vibration quanta provides a direct information on the structure of nuclei close to their ground states. Moreover, some collective states appear to be very robust against the onset of chaos. This is the case of the hot giant dipole built on top of a hot nucleus which seems to survive up to rather high temperatures. Their sudden disappearance is still a subject of controversy. It may be that the mean-field and the associated collective states are playing a crucial role also in catastrophic processes such as the phase-transitions. Indeed, when the system is diluted the collective vibrations may become unstable and it seems that these unstable modes provide a natural explanation to the self organization of the system in drops. Finally, considering the diversity of the different structures of exotic nuclei one may expect new vibration types. All these studies are showing the diversity of the collective motions of strongly correlated quantum systems such as the nucleus but many open questions remain to be solved. (authors)

  20. Collective excitations in nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Chomaz, Ph. [Grand Accelerateur National d`Ions Lourds (GANIL), 14 - Caen (France); Collaboration: La Direction des Sciences de la Matiere du CEA (FR); Le Fonds National de la Recherche Scientifique de Belgique (BE)

    1998-12-31

    The properties of the nucleus cannot be reduced to the properties of its constituents: it is a complex system. The fact that many properties of the nucleus are consequences of the existence of mean-field potential is a manifestation of this complexity. In particular, the nucleons can thus self-organize in collective motions such as giant resonances. Therefore the study of this collective motions is a very good tool to understand the properties of the nucleus itself. The purpose of this article is to stress some aspects of these collective vibrations. We have studied how an ensemble of fermions as the nucleus can self-organize in collective vibrations which are behaving like a gas of bosons in weak interaction. Understanding of these phenomena remains one of the important subjects of actuality in the context of quantal systems in strong interaction. In particular, the study of the states with one or two vibration quanta provides a direct information on the structure of nuclei close to their ground states. Moreover, some collective states appear to be very robust against the onset of chaos. This is the case of the hot giant dipole built on top of a hot nucleus which seems to survive up to rather high temperatures. Their sudden disappearance is still a subject of controversy. It may be that the mean-field and the associated collective states are playing a crucial role also in catastrophic processes such as the phase-transitions. Indeed, when the system is diluted the collective vibrations may become unstable and it seems that these unstable modes provide a natural explanation to the self organization of the system in drops. Finally, considering the diversity of the different structures of exotic nuclei one may expect new vibration types. All these studies are showing the diversity of the collective motions of strongly correlated quantum systems such as the nucleus but many open questions remain to be solved. (authors) 304 refs., 53 figs., 5 tabs.

  1. Neutron rich nuclei around 132Sn

    International Nuclear Information System (INIS)

    Bhattacharya, Sarmishtha

    2016-01-01

    The neutron rich nuclei with few particles or holes in 132 Sn have various experimental and theoretical interest to understand the evolution of nuclear structure around the doubly magic shell closure Z=50 and N=82. Some of the exotic neutron rich nuclei in this mass region are situated near waiting points in the r-process path and are of special astrophysical interest. Neutron rich nuclei near 132 Sn have been studied using fission fragment spectroscopy. The lifetime of low lying isomeric states have been precisely measured and the beta decay from the ground and isomeric states have been characterized using gamma-ray spectroscopy

  2. The spectroscopy of fission fragments

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, W.R. [Department of Physics and Astronomy, University of Manchester, Manchester, M13 9PL (United Kingdom); Collaboration: La Direction des Sciences de la Matiere du CEA (FR); Le Fonds National de la Recherche Scientifique de Belgique (BE)

    1998-12-31

    High-resolution measurements on {gamma} rays from fission fragments have provided a rich source of information, unobtainable at the moment in any other way, on the spectroscopy of neutron-rich nuclei. In recent years important data have been obtained on the yrast- and near yrast-structure of neutron-rich fission fragments. We discuss the scope of measurements which can be made on prompt gamma rays from secondary fission fragments, the techniques used in the experiments and some results recently obtained. (author) 24 refs., 8 figs., 1 tab.

  3. The spectroscopy of fission fragments

    International Nuclear Information System (INIS)

    Phillips, W.R.

    1998-01-01

    High-resolution measurements on γ rays from fission fragments have provided a rich source of information, unobtainable at the moment in any other way, on the spectroscopy of neutron-rich nuclei. In recent years important data have been obtained on the yrast- and near yrast-structure of neutron-rich fission fragments. We discuss the scope of measurements which can be made on prompt gamma rays from secondary fission fragments, the techniques used in the experiments and some results recently obtained. (author)

  4. Jet fragmentation

    International Nuclear Information System (INIS)

    Saxon, D.H.

    1985-10-01

    The paper reviews studies on jet fragmentation. The subject is discussed under the topic headings: fragmentation models, charged particle multiplicity, bose-einstein correlations, identified hadrons in jets, heavy quark fragmentation, baryon production, gluon and quark jets compared, the string effect, and two successful models. (U.K.)

  5. The Peculiarities of the Production and Decay of Superheavy Nuclei

    International Nuclear Information System (INIS)

    Itkis, M. G.; Bogachev, A. A.; Itkis, I. M.; Jandel, M.; Kliman, J.; Knyazheva, G. N.; Kondratiev, N. A.; Kozulin, E. M.; Krupa, L.; Oganessian, Yu. Ts.; Pokrovsky, I. V.; Prokhorova, E. V.; Rusanov, A. Ya.; Sagaidak, R. N.; Beghini, S.; Montagnoli, G.; Scarlassara, F.; Behera, B. R.; Corradi, L.; Fioretto, E.

    2006-01-01

    The interest in the study of the fission process of superheavy nuclei mainly deals with the opportunity to obtain information about the cross-section of the compound nucleus (CN) formation at excitation energies E*≅15-30 MeV. It allows one to estimate the survival probability of the superheavy composite system after evaporation of 1-3 neutrons, i.e. in 'cold' or 'warm' fusion reactions. However, in order to solve this problem deeper understanding of the coalescence processes between colliding nuclei, the competition between fusion-fission and quasi-fission processes is needed. The characteristics of both processes, their manifestation in the experimental observables and the relative contribution to the capture cross-section in dependence on the excitation energies, reaction entrance channel etc were investigated for a wide range of target-projectile combinations. Results of the experiments devoted to the study of the fusion-fission and quasi-fission processes in the reactions of the formation of the superheavy nuclei with Z = 102-122 are presented. The heavy ions 26Mg, 48Ca, 50Ti, 58Fe and 64Ni were used as projectiles. The choice of the reactions with 48Ca and actinide-targets was inspired by the experiments on the production of the isotopes 283112, 289114 and 283116 in Dubna using the same reactions. The 50Ti, 58Fe and 64Ni projectiles were chosen since the corresponding projectile-target combinations lead to the synthesis of even heavier elements. The experiments were carried out at the U-400 accelerator of the Flerov Laboratory of Nuclear Reactions (JINR, Russia) and the XTU Tandem accelerator of the National Laboratory of Legnaro (LNL, Italy) using the time-of-flight spectrometer of fission fragments CORSET. The role of the shell effects, the influence of the entrance channel asymmetry and the deformations of colliding nuclei on the mechanism of the fusion-fission and the competitive process of quasi-fission are discussed. The recent results on synthesis of

  6. Production and de-excitation modes of hot nuclei in the 84Kr + 12C, 84Kr + 27Al, 84Kr + Nat Ti reactions at 26.4, 34.4 and 45.4 MeV/nucleon

    International Nuclear Information System (INIS)

    Faure-Ramstein, B.

    1988-01-01

    The inclusive characteristics of nuclear fragments, of mass greater than 10 uma, from KR + C, Al and Ti reactions at 25, 35 and 45 MeV/u, are investigated. The inverse kinematic method is applied. The analysis of velocity and fragment (mass [fr

  7. Inelastic collisions of neon 22 nuclei with photoemulsion at 4.1 A GeV/c

    International Nuclear Information System (INIS)

    Tolstov, K.D.

    1987-01-01

    Inelastic collisions of neon-22 nuclei accelerated at the JINR synchrophasotron with BR-2 photoemulsion nuclei are investigated. Colliding nuclei fragmentation including their total disintegration, pion production, correlation ratios are studied. There are particular cases of 22 Ne-emulsion collisions, i.e. manifestation of collective effects in inelastic collisions of relativistic nuclei

  8. Nuclear fragmentation

    International Nuclear Information System (INIS)

    Chung, K.C.

    1989-01-01

    An introduction to nuclear fragmentation, with emphasis in percolation ideas, is presented. The main theoretical models are discussed and as an application, the uniform expansion approximation is presented and the statistical multifragmentation model is used to calculate the fragment energy spectra. (L.C.)

  9. Hot Flashes

    Science.gov (United States)

    Hot flashes Overview Hot flashes are sudden feelings of warmth, which are usually most intense over the face, neck and chest. Your skin might redden, as if you're blushing. Hot flashes can also cause sweating, and if you ...

  10. Dynamical effects in the Colomb expansion following nuclear fragmentation

    International Nuclear Information System (INIS)

    Chung, K.C.; Donangelo, R.J.; Schechter, H.

    1987-01-01

    The effects of the Colomb expansion on the fragment Kinetic energy spectrum for a fragmentating hot nuclear system is investigated. In particular, 12 C fragment spectra are calculated and compared with those predicted by the uniform expansion approximation. The results indicate that energy spectra of fragments are quite sensitive to the details of the Coulomb expansion treatment. (Author) [pt

  11. HOT 2015

    DEFF Research Database (Denmark)

    Hannibal, Sara Stefansen

    2016-01-01

    HOT samler og formidler 21 literacykyndiges bud på, hvad der er hot, og hvad der bør være hot inden for literacy – og deres begrundelser for disse bud.......HOT samler og formidler 21 literacykyndiges bud på, hvad der er hot, og hvad der bør være hot inden for literacy – og deres begrundelser for disse bud....

  12. Jet evolution in hot and cold QCD matter

    Energy Technology Data Exchange (ETDEWEB)

    Domdey, Svend Oliver

    2010-07-23

    In this thesis, we study the evolution of energetic partons in hot and cold QCD matter. In both cases, interactions with the medium lead to energy loss of the parton and its transverse momentum broadens. The propagation of partons in cold nuclear matter can be investigated experimentally in deep-inelastic scattering (DIS) on nuclei. We use the dipole model to calculate transverse momentum broadening in DIS on nuclei and compare to experimental data from HERMES. In hot matter, the evolution of the parton shower is strongly modified. To calculate this modification, we construct an additional scattering term in the QCD evolution equations which accounts for scattering of partons in the quark-gluon plasma. With this scattering term, we compute the modified gluon distribution in the shower at small momentum fractions. Furthermore, we calculate the modified fragmentation function of gluons into pions. The scattering term causes energy loss of the parton shower which leads to a suppression of hadrons with large transverse momentum. In the third part of this thesis, we study double dijet production in hadron collisions. This process contains information about the transverse parton distribution of hadrons. As main result, we find that double dijet production will allow for a study of the transverse growth of hadronic wave functions at the LHC. (orig.)

  13. New properties of giant resonances in highly excited nuclei

    International Nuclear Information System (INIS)

    Morsch, H.P.

    1991-01-01

    Studies on the giant dipole resonance in very hot nuclei investigated in heavy ion-induced particle-γ coincidence experiments are reviewed. A signature is found in the γ-decay of excited nuceli which shows direct decay of the giant dipole resonance. This provides a new dimension in giant resonance studies and the possibility to study the dependence of giant resonance energy, width and sum rule strength on excitation energy and rotation of the system. Further, the fact that the giant resonance splits in deformed nuclei provides a unique way to get information on the shape of hot nuclei. First results are obtained on the following questions: (i)What is the nuclear shape at high temperature (T≥2 MeV)? (ii)Is there a phase transition in the nuclear shape at T∼1.7 MeV? (iii)Does motional narrowing exist in hot nuclei? (author). 19 refs., 11 figs

  14. Interactions of 10.6 GeV/n gold nuclei with light and heavy target nuclei in nuclear emulsion

    International Nuclear Information System (INIS)

    Cherry, M.L.; Denes-Jones, P.

    1994-03-01

    We have investigated the particle production and fragmentation of nuclei participating in the interactions of 10.6 GeV/n gold nuclei in nuclear emulsions. A new criteria has been developed to distinguish between the interactions of these gold nuclei with the light (H, C, N, O) and heavy (Ag, Br) target nuclei in the emulsion. This has allowed separate analyzes of the multiplicity and pseudo-rapidity distributions of the singly charged particles emitted in Au-(H, C, N, O) and Au-(Ag, Br) interactions, as well as of the models of breakup of the projectile and target nuclei. The pseudo-rapidity distributions show strong forward asymmetries, particularly for the interactions with the light nuclei. Heavy target nuclei produce a more severe breakup of the projectile gold nucleus than do the lighter targets. A negative correlation between the number of fragments emitted from the target nuclei and the degree of centrality of the collisions has been observed, which can be attributed to the total destruction of the relatively light target nuclei by these very heavy projectile nuclei. (author). 14 refs, 11 figs, 1 tab

  15. The Top-of-Instrument corrections for nuclei with AMS on the Space Station

    Science.gov (United States)

    Ferris, N. G.; Heil, M.

    2018-05-01

    The Alpha Magnetic Spectrometer (AMS) is a large acceptance, high precision magnetic spectrometer on the International Space Station (ISS). The top-of-instrument correction for nuclei flux measurements with AMS accounts for backgrounds due to the fragmentation of nuclei with higher charge. Upon entry in the detector, nuclei may interact with AMS materials and split into fragments of lower charge based on their cross-section. The redundancy of charge measurements along the particle trajectory with AMS allows for the determination of inelastic interactions and for the selection of high purity nuclei samples with small uncertainties. The top-of-instrument corrections for nuclei with 2 < Z ≤ 6 are presented.

  16. Controlled fragmentation

    International Nuclear Information System (INIS)

    Arnold, Werner

    2002-01-01

    Contrary to natural fragmentation, controlled fragmentation offers the possibility to adapt fragment parameters like size and mass to the performance requirements in a very flexible way. Known mechanisms like grooves inside the casing, weaken the structure. This is, however, excluded for applications with high accelerations during launch or piercing requirements for example on a semi armor piercing penetrator. Another method to achieve controlled fragmentation with an additional grid layer is presented with which the required grooves are produced 'just in time' inside the casing during detonation of the high explosive. The process of generating the grooves aided by the grid layer was studied using the hydrocode HULL with respect to varying grid designs and material combinations. Subsequent to this, a large range of these theoretically investigated combinations was contemplated in substantial experimental tests. With an optimised grid design and a suitable material selection, the controlled fragment admits a very flexible adaptation to the set requirements. Additional advantages like the increase of perforation performance or incendiary amplification can be realized with the grid layer

  17. Chameleon fragmentation

    Energy Technology Data Exchange (ETDEWEB)

    Brax, Philippe [Institut de Physique Théorique, CEA, IPhT, CNRS, URA 2306, F-91191Gif/Yvette Cedex (France); Upadhye, Amol, E-mail: philippe.brax@cea.fr, E-mail: aupadhye@anl.gov [Institute for the Early Universe, Ewha University, International Education, Building #601, 11-1, Daehyun-Dong Seodaemun-Gu, Seoul 120-750 (Korea, Republic of)

    2014-02-01

    A scalar field dark energy candidate could couple to ordinary matter and photons, enabling its detection in laboratory experiments. Here we study the quantum properties of the chameleon field, one such dark energy candidate, in an ''afterglow'' experiment designed to produce, trap, and detect chameleon particles. In particular, we investigate the possible fragmentation of a beam of chameleon particles into multiple particle states due to the highly non-linear interaction terms in the chameleon Lagrangian. Fragmentation could weaken the constraints of an afterglow experiment by reducing the energy of the regenerated photons, but this energy reduction also provides a unique signature which could be detected by a properly-designed experiment. We show that constraints from the CHASE experiment are essentially unaffected by fragmentation for φ{sup 4} and 1/φ potentials, but are weakened for steeper potentials, and we discuss possible future afterglow experiments.

  18. Chameleon fragmentation

    International Nuclear Information System (INIS)

    Brax, Philippe; Upadhye, Amol

    2014-01-01

    A scalar field dark energy candidate could couple to ordinary matter and photons, enabling its detection in laboratory experiments. Here we study the quantum properties of the chameleon field, one such dark energy candidate, in an ''afterglow'' experiment designed to produce, trap, and detect chameleon particles. In particular, we investigate the possible fragmentation of a beam of chameleon particles into multiple particle states due to the highly non-linear interaction terms in the chameleon Lagrangian. Fragmentation could weaken the constraints of an afterglow experiment by reducing the energy of the regenerated photons, but this energy reduction also provides a unique signature which could be detected by a properly-designed experiment. We show that constraints from the CHASE experiment are essentially unaffected by fragmentation for φ 4 and 1/φ potentials, but are weakened for steeper potentials, and we discuss possible future afterglow experiments

  19. Bespoke Fragments

    DEFF Research Database (Denmark)

    Kruse Aagaard, Anders

    2017-01-01

    The PhD project Bespoke Fragments is investigating the space emerging in the exploration of the relationship between digital drawing and fabrication, and the field of materials and their properties and capacities. Through a series of different experiments, the project situates itself in a shuttli...

  20. Rock fragmentation

    Energy Technology Data Exchange (ETDEWEB)

    Brown, W.S.; Green, S.J.; Hakala, W.W.; Hustrulid, W.A.; Maurer, W.C. (eds.)

    1976-01-01

    Experts in rock mechanics, mining, excavation, drilling, tunneling and use of underground space met to discuss the relative merits of a wide variety of rock fragmentation schemes. Information is presented on novel rock fracturing techniques; tunneling using electron beams, thermocorer, electric spark drills, water jets, and diamond drills; and rock fracturing research needs for mining and underground construction. (LCL)

  1. Quest for superheavy nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Heenen, P.H. [Universite Libre de Bruxelles, Service de Physique Nucleaire Theorique (Belgium); Nazarewicz, W. [Tennessee Univ., Knoxville, TN (United States). Dept. of Physics; Warsaw Univ. (Poland). Inst. Fizyki Teoretycznej

    2002-02-01

    This article draws the long history of the discovery of new heavy nuclei since its beginning in 1940 when neptunium was found, and presents the current status of research in this field. The last 3 years have brought a number of experimental surprises which have truly rejuvenated the field. In January 1999, scientists from Dubna (Russia) reported the synthesis of 1 atom of element 114 ({sup 298}Uuq) in a hot fusion reaction between a {sup 48}Ca beam and a {sup 244}Pu target. This discovery was followed by 3 other reports from Dubna. First using the {sup 242}Pu({sup 48}Ca,3n) reaction, they produced {sup 287}Uuq. In 1999 the synthesis of another isotope of Z=114, the even-even {sup 288}Uuq was reported. The element Z=116 ({sup 292}Uuh) was discovered as a product of the {sup 248}Cm({sup 48}Ca,4n) reaction. The GSI (Germany) group found a new even isotope of the element 110: {sup 270}Uun and also {sup 272}Uuu (element 111) and {sup 277}Uub (element 112). 2 new isotopes of the element 107: {sup 266}Bh and {sup 267}Bh have been found at Berkeley (Usa). The synthesis of the new element Z=118 ({sup 293}Uuo) announced in 1999 by the Berkeley group was retracted 2 years later. The lifetimes reported for the elements {sup 284}Uub and {sup 280}Uun are by many orders of magnitude longer than those of the isotopes with Z{<=}112 previously discovered at GSI. (A.C.)

  2. Accretion disks in active galactic nuclei

    International Nuclear Information System (INIS)

    Shields, G.A.

    1989-01-01

    Active galactic nuclei (AGN) have taunted astrophysicists for a quarter century. How do these objects produce huge luminosities---in some cases, far outshining our galaxy---from a region perhaps no larger than the solar system? Accretion onto supermassive black holes has been widely considered the best buy in theories of AGN. Much work has gone into accretion disk theory, searches for black holes in galactic nuclei, and observational tests. These efforts have not proved the disk model, but there is progress. Evidence for black holes in the nuclei of nearby galaxies is provided by observations of stellar velocities, and radiation from the disk's hot surface may be observed in the ultraviolet (UV) and neighboring spectral bands. In the review, the author describe some of the recent work on accretion disks in AGN, with an emphasis on points of contact between theory and observation

  3. Fragmentation of giant dipole resonance at finite temperature

    International Nuclear Information System (INIS)

    Vdovin, A.

    2005-01-01

    It is well known that the main part of a width of a collective giant resonance built on the ground state in heavy nuclei is due to coupling of one-phonon vibrational states with more complex ones like two phonon or two-particle - two-hole. So it seems natural that the same idea was also explored in studying of the formation and dependence on temperature of a width of giant resonances built on a compound nuclear state. The first microscopic calculations of a giant dipole resonance width at finite temperature have demonstrated its weak dependence on T whereas the experimental width Γ exp strongly increases up to T≤3 MeV. The observed thermal behaviour of Γ exp was attributed mainly to thermal fluctuations of a nuclear shape at finite T . However, further theoretical studies of the problem have shown a strengthening of the GDR spreading with T. We calculate a fragmentation of the giant dipole resonance in hot spherical nuclei within the approach based on the quasiparticle-phonon model extended to finite temperature in with the formalism of thermofield dynamics. The fragmentation of collective giant dipole vibrations at finite T is due to the coupling with 'two-thermal phonon' configurations. The energies and structures of thermal phonon states are calculated from the thermal RPA temperature dependence of the variance σ th of a theoretical E1 strength function and the experimental GDR width Γ exp in 120 Sn. The coupling of thermal phonons is determined by their fermionic structure. The variance σ th of the E1 strength function is found continuously increasing with temperature. The main reason of this behavior is the coupling of the dipole phonons with very low-lying particle-particle (hole-hole) thermal phonons. These phonons are noncollective ones and they appear only at T≠0. The calculated T dependence of σ th is quite similar to that of the experimental width Γ exp in 120 Sn and 208 Pb

  4. Order in nuclei and transition to chaos

    International Nuclear Information System (INIS)

    Soloviev, V.G.

    1995-01-01

    Based on the statement that there is order in the large and chaos in the small components of nuclear wave functions, the order-to-chaos transition is treated as a transition from the large to small components of wave functions. Therefore, experimental investigation of fragmentation of the many-quasiparticle and quasiparticle-phonon states plays a decisive role. The mixing of closely-spaced states having the same K π in the doubly even well-deformed nuclei is investigated. The quasiparticle-phonon interaction is responsible for fragmentation of the quasiparticle and phonon states and therefore for their mixing. Experimental investigation of the strength distribution of the many-quasiparticle and quasiparticle-phonon states should discover a new region of regularity in nuclei at intermediate excitation energies. A chaotic behaviour of nuclear states can be shifted to higher excitation energies. (author). 21 refs., 1 fig., 1 tab

  5. Order in nuclei and transition to chaos

    International Nuclear Information System (INIS)

    Soloviev, V.G.

    1995-01-01

    Based on the statement that there is order in the large and chaos in the small components of nuclear wave functions, the order-to-chaos transition is treated as a transition from the large to small components of wave functions. Therefore, experimental investigation of fragmentation of the many-quasiparticle and quasiparticle-phonon states a decisive role. The mixing of closely-spaced states having the same K π in the doubly even well-deformed nuclei is investigated. The quasiparticle-phonon interaction is responsible for fragmentation of the quasiparticle and phonon states and therefore for their mixing. Experimental investigation of the strength distribution of the many-quasiparticle and quasiparticle-phonon states should discover a new region of regularity in nuclei at intermediate excitation energies. A chaotic behaviour of nuclear states can be shifted to higher excitation energies. (author). 21 refs., 1 fig., 1 tab

  6. Nuclei and quantum worlds

    International Nuclear Information System (INIS)

    Chomaz, Ph.

    2000-01-01

    This document gathers the slides and their commentaries that have been presented at the conference 'physics and fundamental questions' by P. Chomaz. The author reviews the different quantum aspects of nuclei: tunnel effect, symmetries, magic numbers, wave functions, size, shapes and deformations. The author shows that nuclei are quantum objects of great complexity, their structures are not yet well understood and the study of exotic nuclei will continue bringing valuable information

  7. Production and identification of very exotic nuclei

    International Nuclear Information System (INIS)

    Pougheon, F.

    1986-01-01

    New very exotic nuclei have been produced by fragmentation of the projectile at intermediate energy at GANIL. They have been identified through time of flight and ΔE-E measurements after a magnetic separation with the 0 0 LISE spectrometer. New neutron rich isotopes have been identified up to Z = 26 and evidence for the stability of the new series Tz = -5/2 has been shown. These results improve the knowledge of the neutron and proton drip lines

  8. Pairing correlations in nuclei

    International Nuclear Information System (INIS)

    Baba, C.V.K.

    1988-01-01

    There are many similarities between the properties of nucleons in nuclei and electrons in metals. In addition to the properties explainable in terms of independent particle motion, there are many important co-operative effects suggesting correlated motion. Pairing correlation which leads to superconductivity in metals and several important properties in nuclei , is an exmple of such correlations. An attempt has been made to review the effects of pairing correlations in nuclei. Recent indications of reduction in pairing correlations at high angular momenta is discussed. A comparision between pairing correlations in the cases of nuclei and electrons in metals is attempted. (author). 20 refs., 10 figs

  9. Architectural fragments

    DEFF Research Database (Denmark)

    Bang, Jacob Sebastian

    2018-01-01

    I have created a large collection of plaster models: a collection of Obstructions, errors and opportunities that may develop into architecture. The models are fragments of different complex shapes as well as more simple circular models with different profiling and diameters. In this contect I have....... I try to invent the ways of drawing the models - that decode and unfold them into architectural fragments- into future buildings or constructions in the landscape. [1] Luigi Moretti: Italian architect, 1907 - 1973 [2] Man Ray: American artist, 1890 - 1976. in 2015, I saw the wonderful exhibition...... "Man Ray - Human Equations" at the Glyptotek in Copenhagen, organized by the Philips Collection in Washington D.C. and the Israel Museum in Jerusalem (in 2013). See also: "Man Ray - Human Equations" catalogue published by Hatje Cantz Verlag, Germany, 2014....

  10. The role of cranking frequency in the generation of angular momentum in isospin formalism for nuclei around A=90

    International Nuclear Information System (INIS)

    Mohamed Akbar, A.; Veeraraghavan, S.; Arunachalam, N.

    1998-01-01

    The role of cranking frequency in hot rotating deformed nuclei has been studied with reference to the extraction of several nuclear parameters. In this work, the angular momentum degree of freedom is included in the isospin formalism using statistical theory of hot deformed nuclei

  11. Order against chaos in nuclei

    International Nuclear Information System (INIS)

    Soloviev, V.G.

    1995-01-01

    Order and chaos and order-to-chaos transition are treated in terms of nuclear wave functions. A quasiparticle-phonon interaction is responsible for the fragmentation of one- and many-quasiparticle and phonon states and for the mixing of closely spaced states. Complete damping of one-quasiparticle states cannot be considered as a transition to chaos due to large many-quasiparticle or quasiparticle-phonon terms in their wave functions. An experimental investigation of the strength distribution of many-quasiparticle and quasiparticle-phonon states should uncover a new region of a regularity in nuclei at intermediate excitation energy. A chaotic behaviour of nuclear states can be shifted to higher excitation energies. ((orig.))

  12. Nuclei with exotic constituents

    International Nuclear Information System (INIS)

    Yamazaki, Toshimitsu.

    1990-08-01

    We discuss various interesting features in the behavior of exotic constituents of nuclei such as hyperons and mesons, in particular, with emphases on the aspect of exotic halos which are formed in general by short-range repulsion and long-range attraction. Specifically, Λ and Σ hypernuclei and pionic nuclei are discussed. (author)

  13. Neutron rich nuclei

    International Nuclear Information System (INIS)

    Foucher, R.

    1979-01-01

    If some β - emitters are particularly interesting to study in light, medium, and heavy nuclei, another (and also) difficult problem is to know systematically the properties of these neutron rich nuclei far from the stability line. A review of some of their characteristics is presented. How far is it possible to be objective in the interpretation of data is questioned and implications are discussed

  14. Baryon resonances in nuclei

    International Nuclear Information System (INIS)

    Arenhoevel, H.

    1977-01-01

    The field of baryon resonances in nuclei is reviewed. Theoretical developments and experimental evidence as well are discussed. Special emphasis is laid on electromagnetic processes for the two nucleon system. Some aspects of real isobars in nuclei are touched upon. (orig.) [de

  15. Nuclei in high forms

    International Nuclear Information System (INIS)

    Szymanski, Z.; Berger, J.F.; Heenen, P.H.; Heyde, K.; Haas, B.; Janssens, R.; Paya, D.; Gogny, D.; Huber, G.; Bjoernholm, S.; Brack, M.

    1991-01-01

    The purpose of 1991 Joliot-Curie Summer School is to review the most advances in the understanding of the nuclei physics after the considerable progress in gamma spectroscopy. It covers the following topics: Highly and super-deformed nuclei, nuclear structures, mean-field approach and beyond, fission isomers, nuclear excitations with long lifetime and metal clusters

  16. Pair correlations in nuclei

    International Nuclear Information System (INIS)

    Shimizu, Yoshifumi

    2009-01-01

    Except for the closed shell nuclei, almost all nuclei are in the superconducting state at their ground states. This well-known pair correlation in nuclei causes various interesting phenomena. It is especially to be noted that the pair correlation becomes weak in the excited states of nuclei with high angular momentum, which leads to the pair phase transition to the normal state in the high spin limit. On the other hand, the pair correlation becomes stronger in the nuclei with lower nucleon density than in those with normal density. In the region of neutron halo or skin state of unstable nuclei, this phenomenon is expected to be further enhanced to be observed compared to the ground state of stable nuclei. An overview of those interesting aspects caused via the pair correlation is presented here in the sections titled 'pair correlations in ground states', pair correlations in high spin states' and 'pair correlations in unstable nuclei' focusing on the high spin state. (S. Funahashi)

  17. Eta mesons in nuclei

    International Nuclear Information System (INIS)

    Liu, L.C.

    1987-01-01

    The possibility of producing eta-mesic nuclei by the use of pions is discussed. If these nuclei are observed experimentally, then the binding energies of the eta in this new nuclear matter can be used to extract accurately the eta-N-N* coupling constant in a nucleus. The framework for these calculations is the coupled channel isobar model

  18. Intermittency in 197Au fragmentation

    International Nuclear Information System (INIS)

    Dabrowska, A.; Holynski, R.; Olszewski, A.; Szarska, M.; Wilczynska, B.; Wolter, W.; Wosiek, B.; Cherry, M.L.; Deines-Jones, P.; Jones, W.V.; Sengupta, K.; Wefel, B.

    1995-07-01

    The concept of factorial moments was applied to an analysis of the dynamical fluctuations in the charge distributions of the fragments emitted from gold nuclei with energies 10.6 and < 1.0 GeV/n interacting with emulsion nuclei. Clear evidence for intermittent fluctuations has been found in an analysis using all the particles released from the gold projectile, with a stronger effect observed below 1 GeV/n than at 10.6 GeV/n. For the full data sets, however, the intermittency effect was found to be very sensitive to the singly charged particles, and neglecting these particles strongly reduces the intermittency signal. When the analysis is restricted to the multiply charged fragments, an intermittency effect is revealed only for multifragmentation events, although one that is enhanced as compared to the analysis of all, singly and multiply charged, particles. The properties of the anomalous fractal dimensions suggest a sequential decay mechanism, rather than the existence of possible critical behaviour in the process of nuclear fragmentation. The likely influence of the charge conservation effects and the finite size of decaying systems on the observed intermittency signals was pointed out. (author). 37 refs, 9 figs, 5 tabs

  19. Improved description of the fragmentation of nuclear collective states

    International Nuclear Information System (INIS)

    Soloviev, V.G.

    1984-01-01

    A mathematical method is deveioped for a more accurate description of the fragmentation of one-phonon states forming giant resonances. The method consists in that the one-phonon states already fragmented are used in the two-phonon terms of wave functions. Strength functions are obtained for the exci excitation of collective charge-exchange states ano giant resonances in spherical nuclei

  20. Complex fragment emission at low and high excitation energy

    International Nuclear Information System (INIS)

    Moretto, L.G.

    1986-08-01

    Complex fragment emission has been certified as a compound nucleus process at low energies. An extension of the measurements to heavy ion reactions up to 50 MeV/u shows that most complex fragments are emitted by highly excited compound nuclei formed in incomplete fusion reactions. 12 refs., 26 figs

  1. HOT 2012

    DEFF Research Database (Denmark)

    Lund, Henriette Romme

    Undersøgelse af, hvad der er hot - og hvad der burde være hot på læseområdet med 21 læsekyndige. Undersøgelsen er gennemført siden 2010. HOT-undersøgelsen er foretaget af Nationalt Videncenter for Læsning - Professionshøjskolerne i samarb. med Dansklærerforeningen......Undersøgelse af, hvad der er hot - og hvad der burde være hot på læseområdet med 21 læsekyndige. Undersøgelsen er gennemført siden 2010. HOT-undersøgelsen er foretaget af Nationalt Videncenter for Læsning - Professionshøjskolerne i samarb. med Dansklærerforeningen...

  2. Intermediate Fragment

    DEFF Research Database (Denmark)

    Kruse Aagaard, Anders

    2015-01-01

    This text and its connected exhibition are aiming to reflect both on the thoughts, the processes and the outcome of the design and production of the artefact ‘Intermediate Fragment’ and making as a contemporary architectural tool in general. Intermediate Fragment was made for the exhibition ‘Enga...... of realising an exhibition object was conceived, but expanded, refined and concretised through this process. The context of the work shown here is an interest in a tighter, deeper connection between experimentally obtained material knowledge and architectural design....

  3. Fragmentation based

    Directory of Open Access Journals (Sweden)

    Shashank Srivastava

    2014-01-01

    Gaining the understanding of mobile agent architecture and the security concerns, in this paper, we proposed a security protocol which addresses security with mitigated computational cost. The protocol is a combination of self decryption, co-operation and obfuscation technique. To circumvent the risk of malicious code execution in attacking environment, we have proposed fragmentation based encryption technique. Our encryption technique suits the general mobile agent size and provides hard and thorny obfuscation increasing attacker’s challenge on the same plane providing better performance with respect to computational cost as compared to existing AES encryption.

  4. Bespoke Fragments

    DEFF Research Database (Denmark)

    Kruse Aagaard, Anders

    2016-01-01

    , investigating levels of control and uncertainty encountering with these. Through tangible experiments, the project discusses materiality and digitally controlled fabrications tools as direct expansions of the architect's digital drawing and workflow. The project sees this expansion as an opportunity to connect...... architectural designs, tectonics and aesthetics. In this Ph.D.-project a series a physical, but conceptual, experiment plays the central role in the knowledge production. The experiments result in materialised architectural fragments and tangible experiences. However, these creations also become the driving...

  5. Present and Future Experiments with Stored Exotic Nuclei at GSI

    International Nuclear Information System (INIS)

    Geissel, H.

    2009-01-01

    Recent results and perspectives of experiments with stored exotic nuclei at GSI-FAIR will presented. An overview on the planned NUSTAR experiments will also presented. Relativistic exotic nuclei produced via projectile fragmentation and fission were separated in flight by the fragment separator FRS and injected into the storage-cooler ring ESR for accurate mass- and lifetime measurements. Direct mass measurements of electron-cooled exotic nuclei were performed using time-resolved Schottky spectrometry. Fragments with half-lives shorter than the time required for electron cooling have been investigated by time-of-flight measurements with the ESR being operated in the isochronous mode. This novel experimental technique gives access to all nuclei with half-lives down to the microsecond range and has been successfully applied. Lifetimes of stored bare and few-electron ions have been measured with the goal to study the beta-decay under ionization conditions prevailing in stellar plasma. For the first time the direct observation of bound-state beta decay has been achieved with 2 07T l fragments. The future project FAIR includes a new large-acceptance in-flight separator (Super-FRS) in combination with a new storage ring system (CR, NESR) which will be ideal tools to study exotic nuclei far from stability.(author)

  6. HOT 2014

    DEFF Research Database (Denmark)

    Lund, Henriette

    Undersøgelse af, hvad der er hot - og hvad der burde være hot på læseområdet med 21 læsekyndige. Undersøgelsen er gennemført siden 2010. HOT-undersøgelsen er foretaget af Nationalt Videncenter for Læsning - Professionshøjskolerne i samarb. med Dansklærerforeningen...

  7. Neutron emission and fragment yield in high-energy fission

    International Nuclear Information System (INIS)

    Grudzevich, O. T.; Klinov, D. A.

    2013-01-01

    The KRIS special library of spectra and emission probabilities in the decays of 1500 nuclei excited up to energies between 150 and 250 MeV was developed for correctly taking into account the decay of highly excited nuclei appearing as fission fragments. The emission of neutrons, protons, and photons was taken into account. Neutron emission fromprimary fragments was found to have a substantial effect on the formation of yields of postneutron nuclei. The library was tested by comparing the calculated and measured yields of products originating from the fission of nuclei that was induced by high-energy protons. The method for calculating these yields was tested on the basis of experimental data on the thermal-neutroninduced fission of 235 U nuclei

  8. Similarity of multi-fragmentation of residual nucleus created in nucleus-nucleus interactions at high energies

    International Nuclear Information System (INIS)

    Abdel-Hafiez, A.; Chernyavski, M.M.; Orlova, G.I.; Gulamov, K.G.; Navotny, V.SH.; Uzhinskii, V.V.

    2000-01-01

    Experimental data on multi-fragmentation of residual krypton nuclei created in the interactions of the krypton nuclei with photoemulsion nuclei ut energy of 0.9 GeV per nucleon are presented in a comparison with the analogous data on fragmentation of gold residual nuclei at the energy of 10.7 GeV/nucleon. It is shown for the first time that there are two regimes of nuclear multifragmentation: the former is when less than one-half of nucleons of projectile nucleus are knocked out, the later is when more than one-half of nucleons are knocked out. Residual nuclei with closed masses created at different reactions are fragmenting practically simultaneously when more than one-half of nucleons of original nuclei are knocked out. The evidence of existence of a radial flow of the spectator fragment at the decay of residual krypton nuclei is found

  9. HOT 2011

    DEFF Research Database (Denmark)

    Lund, Henriette Romme

    En undersøgelse af, hvad der er hot - og burde være hot på læseområdet. I undersøgelsen deltager 21 læsekyndige fra praksisfeltet, professionshøjskolerne og forskningsområdet.......En undersøgelse af, hvad der er hot - og burde være hot på læseområdet. I undersøgelsen deltager 21 læsekyndige fra praksisfeltet, professionshøjskolerne og forskningsområdet....

  10. Experiments with stored relativistic exotic nuclei

    International Nuclear Information System (INIS)

    Klepper, O.; Attallah, F.; Beckert, K.; Bosch, F.; Dolinskiy, A.; Eickhoff, H.; Franczak, B.; Franzke, B.; Geissel, H.; Hausmann, M.; Hellstroem, M.; Herfurth, F.; Kluge, H.-J.; Kozhuharov, C.; Muenzenberg, G.; Nolden, F.; Quint, W.; Tradon, T.; Reich, H.; Scheidenberger, C.; Schlitt, B.; Steck, M.; Suemmerer, K.; Vermeeren, L.; Winkler, M.; Winkler, Th.; Falch, M.; Kerscher, Th.; Loebner, K.E.G.; Fujita, Y.; Novikov, Yu.; Patyk, Z.; Stadlmann, J.; Wollnik, H.

    1999-01-01

    Beams of relativistic exotic nuclei were produced, separated and investigated with the combination of the fragment separator FRS and the storage ring ESR. The following experiments are presented: 1) Direct mass measurements of relativistic nickel and bismuth projectile fragments were performed using Schottky spectrometry. Applying electron cooling, the relative velocity spread of the circulating secondary nuclear beams of low intensity was reduced to below 10 -6 . The achieved mass resolving power of m/Δm = 6.5·10 5 (FWHM) in recent measurements represents an improvement by a factor of two compared to authors' previous experiments. The previously unknown masses of more than 100 proton-rich isotopes have been measured in the range of 54≤Z≤84. The results are compared with mass models and estimated values based on extrapolations of experimental values. 2) Exotic nuclei with half-lives shorter than the time required for electron cooling can be investigated by time-of-flight measurements with the ESR being operated in the isochronous mode. This novel experimental technique has been successfully applied in a first measurement with nickel fragments. A mass resolving power of m/Δm = 1.5·10 5 (FWHM) was achieved in this mode of operation. 3) Nuclear half-lives of stored and cooled bare projectile fragments have been measured to study the influence of the ionic charge state on the beta-decay probability

  11. Microcanonical thermodynamics and statistical fragmentation of dissipative systems. The topological structure of the N-body phase space

    Science.gov (United States)

    Gross, D. H. E.

    1997-01-01

    This review is addressed to colleagues working in different fields of physics who are interested in the concepts of microcanonical thermodynamics, its relation and contrast to ordinary, canonical or grandcanonical thermodynamics, and to get a first taste of the wide area of new applications of thermodynamical concepts like hot nuclei, hot atomic clusters and gravitating systems. Microcanonical thermodynamics describes how the volume of the N-body phase space depends on the globally conserved quantities like energy, angular momentum, mass, charge, etc. Due to these constraints the microcanonical ensemble can behave quite differently from the conventional, canonical or grandcanonical ensemble in many important physical systems. Microcanonical systems become inhomogeneous at first-order phase transitions, or with rising energy, or with external or internal long-range forces like Coulomb, centrifugal or gravitational forces. Thus, fragmentation of the system into a spatially inhomogeneous distribution of various regions of different densities and/or of different phases is a genuine characteristic of the microcanonical ensemble. In these cases which are realized by the majority of realistic systems in nature, the microcanonical approach is the natural statistical description. We investigate this most fundamental form of thermodynamics in four different nontrivial physical cases: (I) Microcanonical phase transitions of first and second order are studied within the Potts model. The total energy per particle is a nonfluctuating order parameter which controls the phase which the system is in. In contrast to the canonical form the microcanonical ensemble allows to tune the system continuously from one phase to the other through the region of coexisting phases by changing the energy smoothly. The configurations of coexisting phases carry important informations about the nature of the phase transition. This is more remarkable as the canonical ensemble is blind against these

  12. Nucleons in nuclei, however

    International Nuclear Information System (INIS)

    Grange, P.; Mathiot, J.F.; Roy-Stephan, M.; Frascaria, R.; Gales, S.

    1990-01-01

    The topics presented at the 1989 Joliot-Curie Lectures are reported. Two main subjects were retained: a simplified description of the N-body motion of particles in the quasi-particle configuration; study of the dynamics of nuclear components which are not described by nucleons in their ground state. The following themes were presented: quasiparticles and the Green functions, relativistic aspects of the quasiparticle concept, the dimensions of nucleons in the nuclei and the EMC effect, quarks and gluons in the nuclei, the delta in the nuclei, the strangeness, quasiparticles far from the Fermi sea, diffusion of electrons, stellar evolution and nucleosynthesis [fr

  13. Dynamic polarisation of nuclei

    International Nuclear Information System (INIS)

    Borghini, M.; Abragam, A.

    1961-01-01

    In magnetic fields of about 13000 gauss, at a temperature of 1.5 deg. K, in samples of about 2 mm 3 , we have obtained by the 'solid effect' (application of a magnetic field at an appropriate frequency around 35000 MHz), nuclear polarizations /I of a few percent: 19 per cent for hydrogen nuclei in single crystals of La 2 Mg 3 (NO 3 ) 12 , 24H 2 O; 5 per cent for hydrogen nuclei in polystyrene; 6 per cent for fluorine nuclei in single crystals of LiF. (author) [fr

  14. Framing Fragmentation

    DEFF Research Database (Denmark)

    Bundgaard, Charlotte

    2009-01-01

    Contemporary industrialized architecture based on advanced information technology and highly technological production processes, implies a radically different approach to architecture than what we have experienced in the past. Works of architecture composed of prefabricated building components......, contain distinctive architectural traits, not only based on rational repetition, but also supporting composition and montage as dynamic concepts. Prefab architecture is an architecture of fragmentation, individualization and changeability, and this sets up new challenges for the architect. This paper...... tries to develop a strategy for the architect dealing with industrially based architecture; a strategy which exploits architectural potentials in industrial building, which recognizes the rules of mass production and which redefines the architect’s position among the agents of building. If recent...

  15. Study of multifragmentation: contribution of reduced velocity correlations between particles and fragments; Etude de la multifragmentation: apport des correlations en vitesse reduite entre particules et fragments

    Energy Technology Data Exchange (ETDEWEB)

    Le Fevre, A. [Paris-7 Univ., 75 (France)

    1997-05-14

    This work is focused on the study of fragment and light particle production mechanisms in the multifragmentation process of hot nuclei, which are formed in the central collisions of Xe+Sn at 50 MeV/u. The experiment has been performed with the INDRA multidetector. The central collision events, selected via the flow angle variable, exhibit the presence of a heavy (Z=90) and highly excited (E{sup *}=12.5 MeV/u) isotropic emission source. The comparison of the data with a statistical multifragmentation model (MMMC) and a dynamical model (BNV) makes us conclude that the multifragmentation can only be explained in the frame of a relatively cold process, around 6 MeV/u of thermal excitation energy, preceded by a primary emission stage of the expanding source, during which nearly one third of the excitation energy is dissipated. In addition, it appears that the fragment energy spectra are not explained by a purely thermal process, and that one has to put forward an expansion collective motion, of 2 MeV/u of energy, following the compression of the compound system. In order to precise the existence of a two-step particle emission (primary and secondary), we have developed and applied an original method of reduced velocity correlations between particles and fragments. It has allowed us to underline two distinct origins for the particle production: one corresponding to secondary emissions, coming from the fragments, and the other one, associated with emissions which occur prior to the fragment production. At last, it has allowed us, also to bring out a hierarchy in the emission time in the decay process, with respect to the particle type. (author) 90 refs.

  16. Study of fragmentation reactions of light nucleus

    International Nuclear Information System (INIS)

    Toneli, David Arruda; Carlson, Brett Vern

    2011-01-01

    Full text: The decay of the compound nucleus is traditionally calculated using a sequential emission model, such as the Weisskopf-Ewing or Hauser-Feshbach ones, in which the compound nucleus decays through a series of residual nuclei by emitting one particle at a time until there is no longer sufficient energy for further emission. In light compound nucleus, however, the excitation energy necessary to fully disintegrate the system is relatively easy to attain. In such cases, decay by simultaneous emission of two or more particles becomes important. A model which takes into account all these decay is the Fermi fragmentation model. Recently, the equivalence between the Fermi fragmentation model and statistical multifragmentation model used to describe the decay for highly excited fragments for reactions of heavy ions was demonstrated. Due the simplicity of the thermodynamic treatment used in the multifragmentation model, we have adapted it to the calculation of Fermi breakup of light nuclei. The ultimate goal of this study is to calculate the distribution of isotopes produced in proton-induced reactions on light nuclei of biological interest, such as C, O e Ca. Although most of these residual nuclei possess extremely short half-lives and thus represent little long-term danger, they tend to be deficient in neutrons and to decay by positron emission, which allows the monitoring of proton radiotherapy by PET (Positron Emission Tomography). (author)

  17. Relativistic exotic nuclei as projectile beams. New perspectives of studies on the properties of nuclei

    International Nuclear Information System (INIS)

    Geissel, H.

    1997-03-01

    Examinations of the production cross-sections and the kinematics permitted refinement of model concepts of the peripheral reactions in exotic nuclei at energies from 100 to 1000 A MeV. Due to the strong selectivity and resolution achieved it was possible to discover a large number of novel isotopes at the fragment separator FRS, despite the relatively low projectile beam intensities of the SIS. The two twice magic nuclei found, Ni 78 and Sn 100, are particularly interesting, as they could not be measured so far with other experimental systems. Fission of relativistic uranium ions proved to be a particularly successful process yielding many medium-heavy, neutron-rich nuclei. Insight into the structure of light neutron halos could be improved. The superlarge spatial dimensions of the nuclear halos is discussed. (orig./CB) [de

  18. Quarks in nuclei

    International Nuclear Information System (INIS)

    Roberts, R.G.

    1984-11-01

    The paper concerns the behaviour of quarks in nuclei. Confinement size changes and dynamical rescaling; A dependence; low-x region; gluons and confinement size; and nucleons in a nucleus; are all discussed. (U.K.)

  19. The shape of nuclei

    International Nuclear Information System (INIS)

    Mackintosh, R.S.

    1977-01-01

    For the class of nuclei which are 'strongly deformed' it is possible to introduce the idea of an empirically measurable static nuclear shape. The limitations of this concept as applied to nuclei (fundamentally quantum-mechanical objects) are discussed. These are basically the limitations of the rotational model which must be introduced in order to define and measure nuclear shape. A unified discussion of the ways in which the shape has been parametrized is given with emphasis on the fact that different parametrizations correspond to different nuclear structures. Accounts of the various theoretical procedures for calculating nuclear shapes and of the interaction between nuclear shapes and nuclear spectroscopy are given. A coherent account of a large subset of nuclei (strongly deformed nuclei) can be given by means of a model in which the concept of nuclear shape plays a central role. (author)

  20. Structure of Warm Nuclei

    International Nuclear Information System (INIS)

    Aaberg, S.; Uhrenholt, H.

    2009-01-01

    We study the structure of nuclei in the energy region between the ground state and the neutron separation energy, here called warm nuclei. The onset of chaos in the nucleus as excitation energy is increased is briefly reviewed. Chaos implies fluctuations of energies and wave functions qualitatively the same for all chaotic nuclei. On the other hand, large structure effects are seen, e.g. in the level-density function at same excitation energies. A microscopic model for the level density is reviewed and we discuss effects on structure of the total level-density function, parity enhancement, and the spin distribution function. Comparisons to data are performed at the neutron separation energy for all observed nuclei, and structure of the level-density function for a few measured cases. The role of structure effects in the level-density function for fission dynamics is exemplified.

  1. Formation and de-excitation of hot nuclei in reactions induced by proton beams (475 MeV and 2 GeV) and {sup 3}He beam (2 GeV); Formation et desexcitation des noyaux chauds dans les reactions induites par des faisceaux de protons (475 MeV et 2 GeV) et d`{sup 3}He(2 GeV)

    Energy Technology Data Exchange (ETDEWEB)

    Ledoux, X.

    1995-04-01

    We are studying the formation and the de-excitation of hot nuclei created in reactions induced by light high energy projectiles. These reactions, described in a two step model: an intranuclear cascade followed by an evaporation phase, produce nuclei in which the collective modes (compression, rotation, deformation) are weakly excited. By measuring the neutron multiplicities, event by event with ORION, and the light charged particle energies and multiplicities one can evaluate the excitation energy distribution of the nuclei. At the same time, theoretical simulations are carried out using the intranuclear cascade code developed by J. Cugnon and the statistical de-excitation code GEMINI. The good agreement with experimental results indicate that 10% of the p-nucleus interactions lead to temperatures greater than 5 MeV. The observation of the fission of a nucleus with a temperature close to 5 MeV shows that the nucleus behaves as a set of bound nucleons and, that the temperature stability limit is not yet reached. The observed decline of fission probability at high excitation energies is most likely to be correlated to the appearance of an other de-excitation process (evaporation residues emission or multifragmentation) which could not be experimentally detected. Finally, in the last chapter, we briefly present the principle of transmutation for long-lived nuclear waste with a proton accelerator and underline the interest of the present work in such studies. (author). 54 refs., 80 figs., 13 tabs.

  2. Explosive fragmentation

    Science.gov (United States)

    Vledouts, Alexandre; Graña-Otero, José; Quinard, Joel; Vandenberghe, Nicolas; Villermaux, Emmanuel

    2013-11-01

    We report on an experiment consisting in forcing the fast radial expansion of a spherical liquid shell. The shell is formed by the capillary pinch off of a water thin annular jet surrounding a jet of reactive gaseous mixture at ambient pressure. The encapsulated gas in the resulting water bubble is a mixture of Hydrogen and Oxygen in controlled relative proportions, which is ignited by a laser plasma aimed at the center of the bubble. The strongly exothermic combustion of the mixture induces the expansion of the hot burnt gas, pushing the shell radially outwards in a violently accelerated motion. That motion triggers the instability of the shell, developing thickness modulations ultimately piercing it in a number of holes. The capillary retraction of the holes concentrates the liquid constitutive of the shell into a web of ligaments, whose breakup leads to stable drops. We document the overall process, from the kinematics of the shell initial expansion, to the final drops size distribution as a function of the composition of the gas mixture and bubble shell thickness.

  3. Nuclear energy release from fragmentation

    Energy Technology Data Exchange (ETDEWEB)

    Li, Cheng [The Key Laboratory of Beam Technology and Material Modification of Ministry of Education, College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Beijing Radiation Center, Beijing 100875 (China); Souza, S.R. [Instituto de Física, Universidade Federal do Rio de Janeiro Cidade Universitária, Caixa Postal 68528, 21945-970 Rio de Janeiro (Brazil); Tsang, M.B. [The Key Laboratory of Beam Technology and Material Modification of Ministry of Education, College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Beijing Radiation Center, Beijing 100875 (China); National Superconducting Cyclotron Laboratory and Physics and Astronomy Department, Michigan State University, East Lansing, MI 48824 (United States); Zhang, Feng-Shou, E-mail: fszhang@bnu.edu.cn [The Key Laboratory of Beam Technology and Material Modification of Ministry of Education, College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Beijing Radiation Center, Beijing 100875 (China); Center of Theoretical Nuclear Physics, National Laboratory of Heavy Ion Accelerator of Lanzhou, Lanzhou 730000 (China)

    2016-08-15

    It is well known that binary fission occurs with positive energy gain. In this article we examine the energetics of splitting uranium and thorium isotopes into various numbers of fragments (from two to eight) with nearly equal size. We find that the energy released by splitting {sup 230,232}Th and {sup 235,238}U into three equal size fragments is largest. The statistical multifragmentation model (SMM) is applied to calculate the probability of different breakup channels for excited nuclei. By weighing the probability distributions of fragment multiplicity at different excitation energies, we find the peaks of energy release for {sup 230,232}Th and {sup 235,238}U are around 0.7–0.75 MeV/u at excitation energy between 1.2 and 2 MeV/u in the primary breakup process. Taking into account the secondary de-excitation processes of primary fragments with the GEMINI code, these energy peaks fall to about 0.45 MeV/u.

  4. Search for Fractionally Charged Nuclei in High-Energy Oxygen-Lead Collisions

    CERN Multimedia

    2002-01-01

    We propose to use stacks of CR-39 plastic track detectors to look for fractionally charged projectile fragments produced in collisions of high-energy oxygen, sulfur, and calcium nuclei with a lead target. The expected charge resolution is @s^z~=~0.06e for fragments with 17e/3~@$<$~Z~@$<$~23e/3. We request that two target + stack assemblies be exposed to 1~x~10|5 oxygen nuclei at maximum available energy.

  5. Mechanism of disintegration of sup 2 sup 3 sup 8 U nuclei by relativistic projectiles

    CERN Document Server

    Andronenko, L N; Kravtsov, A V; Solyakin, G E

    2002-01-01

    The sup 2 sup 3 sup 8 U nuclei disintegration through the 16 GeV energy protons and sup 3 He 2 GeV energy nuclei are considered. The pulse mechanism compensation is proposed to explain the formation of collinear mass fragments accompanied by a large amount of charged secondaries and neutrons flying on the m sub 1 relativistic particle heavy nuclei on the account of the particle emission with the mass m sub 2 > m sub 1

  6. Mini-Proceedings of ECT Workshop Strangeness in Nuclei

    CERN Document Server

    Zmeskal, J

    2011-01-01

    This workshop brought together international experts in the research area of strangeness in nuclei physics, working on theory as well as on experiments, to discuss the present status, to develop new methods of analysis and to have the opportunity for brainstorming towards future studies, going towards a deeper understanding of the hot topics in the low-energy QCD in the strangeness sector.

  7. Structure functions of nucleons and nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Bentz, Wolfgang; Ito, Takuya [Department of Physics, Tokai University, Kanagawa (Japan); Cloet, Ian [Department of Physics, University of Washington, Seattle (United States); Thomas, Anthony [Jefferson Lab., Newport News, VA (United States); Yazaki, Koichi [RIKEN, Wako-shi, Saitama (Japan)

    2009-07-01

    We use an effective chiral quark theory to calculate the quark distributions and structure functions of nucleons and nuclei. The description of the single nucleon is based on the Faddeev framework, and nuclear systems are described in the mean field approximation. Particular amphasis is put on the prediction of the polarized EMC effect in nuclei, and on applications to deep inelastic neutrino-nucleus scattering. Concerning the polarized EMC effect, we discuss the quenching of the quark spin sum in nuclei and its implications for the spin dependent nuclear structure functions, and present results for several nuclei where an experimental observation is feasible. Concerning the case of deep inelastic neutrino-nucleus scattering, we estimate the effect of medium modifications of the quark distribution functions on the measured cross sections, and discuss an interesting resolution of the so called NuTeV anomaly. Finally, we discuss extensions of our model to describe fragmentation functions for semi-inclusive processes. The connection between our effective quark model description and the jet model of Field and Feynman is discussed.

  8. Fission dynamics of superheavy nuclei formed in uranium induced reactions

    International Nuclear Information System (INIS)

    Gurjit Kaur; Sandhu, Kirandeep; Sharma, Manoj K.

    2017-01-01

    The compound nuclear system follows symmetric fission if the competing processes such as quasi-elastic, deep inelastic, quasi-fission etc are absent. The contribution of quasi fission events towards the fusion-fission mechanism depends on the entrance channel asymmetry of reaction partners, deformations and orientations of colliding nuclei beside the dependence on energy and angular momentum. Usually the 209 Bi and 208 Pb targets are opted for the production of superheavy nuclei with Z CN =104-113. The nuclei in same mass/charge range can also be synthesized using actinide targets + light projectiles (i.e. asymmetric reaction partners) via hot fusion interactions. These actinide targets are prolate deformed which prefer the compact configurations at above barrier energies, indicating the occurrence of symmetric fission events. Here an attempt is made to address the dynamics of light superheavy system (Z CN =104-106), formed via hot fusion interactions involving actinide targets

  9. HOT 2010

    DEFF Research Database (Denmark)

    Lund, Henriette Romme

    En undersøgelse af, hvad der er hot - og burde være hot på læseområdet. I undersøgelsen deltager en række læsekyndige fra praksisfeltet, professionshøjskolerne og forskningsområdet. Undersøgelsen er gentaget hvert år siden 2010.......En undersøgelse af, hvad der er hot - og burde være hot på læseområdet. I undersøgelsen deltager en række læsekyndige fra praksisfeltet, professionshøjskolerne og forskningsområdet. Undersøgelsen er gentaget hvert år siden 2010....

  10. HOT 2013

    DEFF Research Database (Denmark)

    Lund, Henriette Romme

    En undersøgelse af, hvad der er hot - og burde være hot på læseområdet. I undersøgelsen deltager en række læsekyndige fra praksisfeltet, professionshøjskolerne og forskningsområdet. Undersøgelsen er gentaget hvert år siden 2010.......En undersøgelse af, hvad der er hot - og burde være hot på læseområdet. I undersøgelsen deltager en række læsekyndige fra praksisfeltet, professionshøjskolerne og forskningsområdet. Undersøgelsen er gentaget hvert år siden 2010....

  11. Isospin Conservation in Neutron Rich Systems of Heavy Nuclei

    Science.gov (United States)

    Jain, Ashok Kumar; Garg, Swati

    2018-05-01

    It is generally believed that isospin would diminish in its importance as we go towards heavy mass region due to isospin mixing caused by the growing Coulomb forces. However, it was realized quite early that isospin could become an important and useful quantum number for all nuclei including heavy nuclei due to neutron richness of the systems [1]. Lane and Soper [2] also showed in a theoretical calculation that isospin indeed remains quite good in heavy mass neutron rich systems. In this paper, we present isospin based calculations [3, 4] for the fission fragment distributions obtained from heavy-ion fusion fission reactions. We discuss in detail the procedure adopted to assign the isospin values and the role of neutron multiplicity data in obtaining the total fission fragment distributions. We show that the observed fragment distributions can be reproduced rather reasonably well by the calculations based on the idea of conservation of isospin. This is a direct experimental evidence of the validity of isospin in heavy nuclei, which arises largely due to the neutron-rich nature of heavy nuclei and their fragments. This result may eventually become useful for the theories of nuclear fission and also in other practical applications.

  12. Fragmentation of jets into hadrons with strangeness in Pb-Pb collisions in ALICE at the LHC

    Energy Technology Data Exchange (ETDEWEB)

    Zimmermann, Alice [Physikalisches Institut Heidelberg (Germany); Collaboration: ALICE-Collaboration

    2014-07-01

    The research programme of the ALICE experiment at the LHC focuses on the so-called Quark-Gluon Plasma, a state of matter where quarks and gluons are deconfined. The measurement of particle jets from fragmentation of hard scatterings of partons in the colliding nuclei allows to study parton energy loss in the hot and dense medium and constrains the modelling of such a phenomenon. By measuring yields of particles like K{sup 0}{sub s}, Λ and anti Λ of low to intermediate momenta within jet cones, fragmentation into strange hadrons, as well as the baryon-meson ratio in jets can be studied. In this contribution we present first results on K{sup 0}{sub s}, Λ and anti Λ production in jets in Pb-Pb collisions at √(s{sub NN}) = 2.76 TeV. The analysis is further performed in different centrality classes, representing collisions with different impact parameters. The strangeness identified fragmentation distributions are compared to first results on inclusive fragmentation in Pb-Pb collisions.

  13. A fragment separator at LBL for beta-NMR experiment

    International Nuclear Information System (INIS)

    Matsuta, K.; Ozawa, A.; Nojiri, Y.; Minamisono, T.; Fukuda, M.; Kitagawa, A.; Ohtsubo, T.; Momota, S.; Fukuda, S.; Matsuo, Y.; Takechi, H.; Minami, I.; Sugimoto, K.; Tanihata, I.; Omata, K.; Alonso, J.R.; Krebs, G.F.; Symons, T.J.M.

    1992-03-01

    The Beam 44 fragment separator was built at the Bevalac of LBL for NMR studies of beta emitting nuclei. 37 K, 39 Ca, and 43 Ti fragments originating from 40 Ca and 46 Ti primary beams were separated by the separator for NMR studies on these nuclei. Nuclear spin polarization was created in 39 Ca and 43 Ti using the tilted foil technique (TFT), and the magnetic moment of 43 Ti was deduced. Fragment polarization was measured for 37 K and 39 Ca emitted to finite deflection angles. The Beam 44 fragment separator in combination with a proper polarization technique, such as TFT or fragment polarization, has been very effective for such NMR studies

  14. Fragmentation of the 56Fe in Al at 1.88A GeV

    International Nuclear Information System (INIS)

    Bhattacharyya, D.P.; Pal, P.; Basu, B.; Rakshit, R.; Mukherjee, S.C.

    1988-01-01

    The production of fragmented nuclei from relativistic 56 Fe beam available from LBL Bevalac at 1.88A GeV has been studied using CR-39 (DOP) passive detector placed at an angle of 60 degrees with respect to the beam. The histogram showing the experimental frequency distribution of minor axes of the elliptic etch pit shows the presence of the fragmented nuclei produced with charge number Z from 25 up to 21. The histogram further reveals the presence of nuclei with Z=27 and 28. The production of nuclei heavier than 56 Fe is possibly due to the charge exchange or pick-up phenomena

  15. Study of multifragmentation: contribution of reduced velocity correlations between particles and fragments

    International Nuclear Information System (INIS)

    Le Fevre, A.

    1997-01-01

    This work is focused on the study of fragment and light particle production mechanisms in the multifragmentation process of hot nuclei, which are formed in the central collisions of Xe+Sn at 50 MeV/u. The experiment has been performed with the INDRA multidetector. The central collision events, selected via the flow angle variable, exhibit the presence of a heavy (Z=90) and highly excited (E * =12.5 MeV/u) isotropic emission source. The comparison of the data with a statistical multifragmentation model (MMMC) and a dynamical model (BNV) makes us conclude that the multifragmentation can only be explained in the frame of a relatively cold process, around 6 MeV/u of thermal excitation energy, preceded by a primary emission stage of the expanding source, during which nearly one third of the excitation energy is dissipated. In addition, it appears that the fragment energy spectra are not explained by a purely thermal process, and that one has to put forward an expansion collective motion, of 2 MeV/u of energy, following the compression of the compound system. In order to precise the existence of a two-step particle emission (primary and secondary), we have developed and applied an original method of reduced velocity correlations between particles and fragments. It has allowed us to underline two distinct origins for the particle production: one corresponding to secondary emissions, coming from the fragments, and the other one, associated with emissions which occur prior to the fragment production. At last, it has allowed us, also to bring out a hierarchy in the emission time in the decay process, with respect to the particle type. (author)

  16. Cosmology and unstable nuclei

    International Nuclear Information System (INIS)

    Schramm, D.N.

    1995-01-01

    Primordial nucleosynthesis has established itself as one of the three pillars of Big Bang cosmology. Many of the Big Bang Nucleosynthesis reactions involve unstable nuclei. Hence there is a tight relationship hetween the subject of this conference and cosmology. The prime role of unstable nuclei in cosmology is related to lithium synthesis and the lack of cosmological synthesis of Be and B. These nuclei will thus be focused upon. Nucleosynthesis involves comparing calculated abundances with observed abundances. In general, abundance determinations are dominated by systematic rather than statistical errors, and work on bounding systematics is crucial. The quark-hadron inspired inhomogeneous calculations now unanimously agree that only relatively small variations in Ω b are possible vis-a-vis the homogeneous model; hence the robustness of Ω b ∼0.05 is now apparent. (These calculations depend critically on unstable nuclei.) The above argues that the bulk of the baryons in the universe are not producing visible light. A comparison with the ROSAT cluster data is also shown to be consistent with the standard BBN model. Ω b ∼1 seems to be definitely excluded, so if Ω TOTAL =1, as some recent observations may hint, then non-baryonic dark matter is required. The implications of the recently reported halo microlensing events are discussed. In summary, it is argued that the physics of unstable nuclei affects the fundamental dark matter argument. ((orig.))

  17. Analysis of multi-fragmentation reactions induced by relativistic heavy ions using the statistical multi-fragmentation model

    Energy Technology Data Exchange (ETDEWEB)

    Ogawa, T., E-mail: ogawa.tatsuhiko@jaea.go.jp [Research Group for Radiation Protection, Division of Environment and Radiation Sciences, Nuclear Science and Engineering Directorate, Japan Atomic Energy Agency, Shirakata-Shirane, Tokai, Ibaraki 319-1195 (Japan); Sato, T.; Hashimoto, S. [Research Group for Radiation Protection, Division of Environment and Radiation Sciences, Nuclear Science and Engineering Directorate, Japan Atomic Energy Agency, Shirakata-Shirane, Tokai, Ibaraki 319-1195 (Japan); Niita, K. [Research Organization for Information Science and Technology, Shirakata-shirane, Tokai, Ibaraki 319-1188 (Japan)

    2013-09-21

    The fragmentation cross-sections of relativistic energy nucleus–nucleus collisions were analyzed using the statistical multi-fragmentation model (SMM) incorporated with the Monte-Carlo radiation transport simulation code particle and heavy ion transport code system (PHITS). Comparison with the literature data showed that PHITS-SMM reproduces fragmentation cross-sections of heavy nuclei at relativistic energies better than the original PHITS by up to two orders of magnitude. It was also found that SMM does not degrade the neutron production cross-sections in heavy ion collisions or the fragmentation cross-sections of light nuclei, for which SMM has not been benchmarked. Therefore, SMM is a robust model that can supplement conventional nucleus–nucleus reaction models, enabling more accurate prediction of fragmentation cross-sections.

  18. Analysis of multi-fragmentation reactions induced by relativistic heavy ions using the statistical multi-fragmentation model

    International Nuclear Information System (INIS)

    Ogawa, T.; Sato, T.; Hashimoto, S.; Niita, K.

    2013-01-01

    The fragmentation cross-sections of relativistic energy nucleus–nucleus collisions were analyzed using the statistical multi-fragmentation model (SMM) incorporated with the Monte-Carlo radiation transport simulation code particle and heavy ion transport code system (PHITS). Comparison with the literature data showed that PHITS-SMM reproduces fragmentation cross-sections of heavy nuclei at relativistic energies better than the original PHITS by up to two orders of magnitude. It was also found that SMM does not degrade the neutron production cross-sections in heavy ion collisions or the fragmentation cross-sections of light nuclei, for which SMM has not been benchmarked. Therefore, SMM is a robust model that can supplement conventional nucleus–nucleus reaction models, enabling more accurate prediction of fragmentation cross-sections

  19. Cosmology and the origin of nuclei

    International Nuclear Information System (INIS)

    Narlikar, Jayant V.

    2010-01-01

    The problem of explaining the origin of all the chemical elements found in the universe is a central problem in astrophysics. In the 1940s Fred Hoyle suggested that they were cooked inside stars, starting with nucleosynthesis of neutrons and protons. In the same decade George Gamow argued that in a hot big bang universe in the first few minutes, the ambient conditions were suitable for formation of nuclei. This paper will review the progress of both these ideas and show that a reasonable compromise between these ideas can be found today. (authors)

  20. Critical-point nuclei

    International Nuclear Information System (INIS)

    Clark, R.M.

    2004-01-01

    It has been suggested that a change of nuclear shape may be described in terms of a phase transition and that specific nuclei may lie close to the critical point of the transition. Analytical descriptions of such critical-point nuclei have been introduced recently and they are described briefly. The results of extensive searches for possible examples of critical-point behavior are presented. Alternative pictures, such as describing bands in the candidate nuclei using simple ΔK = 0 and ΔK = 2 rotational-coupling models, are discussed, and the limitations of the different approaches highlighted. A possible critical-point description of the transition from a vibrational to rotational pairing phase is suggested

  1. Fragmentation in 28Si-emulsion interactions at 3.7A GeV

    International Nuclear Information System (INIS)

    Singh, B.K.; Tuli, S.K.

    1999-01-01

    The results on fragmentation of a 3.7A GeV 28 Si projectile in interactions with different target nuclei in nuclear emulsion are presented. Limiting fragmentation behaviour of the projectile fragments is achieved at this energy. It is shown that the factorization principle for fragmentation cross-sections holds for light fragments only. A bond percolation prescription is able to reproduce the experimental observations for fragments with charge 4≤Z≤10. A rise in the production of helium fragments is also predicted by bond percolation

  2. Weak interactions with nuclei

    International Nuclear Information System (INIS)

    Walecka, J.D.

    1983-01-01

    Nuclei provide systems where the strong, electomagnetic, and weak interactions are all present. The current picture of the strong interactions is based on quarks and quantum chromodynamics (QCD). The symmetry structure of this theory is SU(3)/sub C/ x SU(2)/sub W/ x U(1)/sub W/. The electroweak interactions in nuclei can be used to probe this structure. Semileptonic weak interactions are considered. The processes under consideration include beta decay, neutrino scattering and weak neutral-current interactions. The starting point in the analysis is the effective Lagrangian of the Standard Model

  3. Quarks in nuclei

    International Nuclear Information System (INIS)

    Rho, M.; CEA Centre d'Etudes Nucleaires de Saclay, 91 - Gif-sur-Yvette

    1983-01-01

    Some features of quark degrees of freedom in nuclei are discussed in the light of recent developments in QCD. The principal aim of this talk is to propose, and give a tentative support to, the motion that one can study through nuclear matter different facets of the vacuum structure implied by quantum chromodynamics (QCD). This will be done using the recent (exciting) results obtained in particle physics, in particular lattice gauge calculations. Relevance of this aspect of problem to quark degrees of freedom as well as meson degrees of freedom in nuclei will be discussed. (orig.)

  4. Disintegration of comet nuclei

    Science.gov (United States)

    Ksanfomality, Leonid V.

    2012-02-01

    The breaking up of comets into separate pieces, each with its own tail, was seen many times by astronomers of the past. The phenomenon was in sharp contrast to the idea of the eternal and unchangeable celestial firmament and was commonly believed to be an omen of impending disaster, especially for comets with tails stretching across half the sky. It is only now that we have efficient enough space exploration tools to see comet nuclei and even - in the particular case of small comet Hartley-2 in 2010 - to watch their disintegration stage. There are also other suspected candidates for disintegration in the vast family of comet nuclei and other Solar System bodies.

  5. Particles and nuclei, letters

    International Nuclear Information System (INIS)

    2002-01-01

    The present collection of letters from JINR, Dubna, contains seven separate records on kinematic separation and mass analysis of heavy recoiling nuclei, dynamical effects prior to heavy ion fusion, VACTIV-DELPHI graphical dialog based program for the analysis of gamma-ray spectra, irradiation of nuclear emulsions in relativistic beams of 6 He and 3 H nuclei, optical and structural investigations of PLZT x/65/35 (x = 4, 8 %) ferroelectric ceramics irradiated by a high-current pulsed electron beam, the oscillating charge and first evidence for neutrinoless double beta decay

  6. Particles and nuclei, letters

    International Nuclear Information System (INIS)

    2001-01-01

    The present collection of letters from JINR, Dubna, contains seven separate records on physics from extra dimensions, new physics in the new millennium with GENIUS: double beta decay, dark matter, solar neutrinos, the (μ - , e + ) conversion in nuclei mediated by light Majorana neutrinos, exotic muon-to-positron conversion in nuclei: partial transition sum evaluation by using shell model, solar neutrino problem accounting for self consistent magnetohydrodynamics solution for solar magnetic fields, first neutrino observations from the Sudbury neutrino observatory and status report on BOREXINO and results of the muon-background measurements at CERN

  7. Rotational motion in nuclei

    International Nuclear Information System (INIS)

    Bohr, A.

    1976-01-01

    Nuclear structure theories are reviewed concerned with nuclei rotational motion. The development of the deformed nucleus model facilitated a discovery of rotational spectra of nuclei. Comprehensive verification of the rotational scheme and a successful classification of corresponding spectra stimulated investigations of the rotational movement dynamics. Values of nuclear moments of inertia proved to fall between two marginal values corresponding to rotation of a solid and hydrodynamic pattern of an unrotating flow, respectively. The discovery of governing role of the deformation and a degree of a symmetry violence for determining rotational degrees of freedon is pointed out to pave the way for generalization of the rotational spectra

  8. Are cometary nuclei primordial rubble piles?

    Science.gov (United States)

    Weissman, P. R.

    1986-01-01

    Whipple's icy conglomerate model for the cometary nucleus has had considerable sucess in explaining a variety of cometary phenomena such as gas production rates and nongravitational forces. However, as discussed here, both observational evidence and theoretical considerations suggest that the cometary nucleus may not be a well-consolidated single body, but may instead be a loosely bound agglomeration of smaller fragments, weakly bonded and subject to occasional or even frequent disruptive events. The proposed model is analogous to the 'rubble pile' model suggested for the larger main-belt asteroids, although the larger cometary fragments are expected to be primordial condensations rather than collisionally derived debris as in the asteroid case. The concept of cometary nuclei as primordial rubble piles is proposed as a modification of the basic Whipple model, not as a replacement for it.

  9. The resonance neutron fission on heavy nuclei

    International Nuclear Information System (INIS)

    Kopach, Yu.N.; Popov, A.B.; Furman, V.I.; Alfimenkov, V.P.; Lason', L.; Pikel'ner, L.B.; ); Gonin, N.N.; Kozlovskij, L.K.; Tambovtsev, D.I.; Gagarskij, A.M.; Petrov, G.A.; Sokolov, V.E.

    2001-01-01

    A new approach to the description of the fission, similar to the well-known reaction theory and based on the helicity representation for the exit fission channels, is briefly summarized. This approach allows one to connect the multimodal fission representation with A. Bohr's concept of the fission transition states and to obtain formulae for the partial and differential fission cross sections. The formulae are used for analysis of the angular anisotropy of fragments in the neutron resonance induced fission of aligned 235 U nuclei and of the P-even angular forward-backward and right-left correlations of fragments oe the P-odd correlations caused by the interference of s- and p-wave neutron resonances [ru

  10. New results with stored exotic nuclei at relativistic energies

    Energy Technology Data Exchange (ETDEWEB)

    Bosch, F. (Fritz); Boutin, D. (Daniel); Fastermann, T. (Thomas); Falch, M. (Markus); Franzke, B. (Bernhard); Hausmann, M. (Marc); Hellstrom, M. (Margarete); Kaza, E. (Evangelia); Kerscher, T. (Thomas); Klepper, O. (Otto); Kluge, H.-Jürgen; Kozhuharov, C. (Christophor); Kratz, K. L.; Litinov, S. A. (Sergei A); Lobner, G. K. E. (Gunther K. E.); Maier, L. (Ludwig); Matos, M. (Milan); Munzenberg, G. (Gottfried); Nolden, F. (Fritz); Novikov, Y. N. (Yuri N.); Ohtsubo, T. (Takashi); Ostrowski, A. (Alexander); Patyk, Z. (Zygmund); Pfeiffer, B.; Portillo, M. (Mauricio); Radon, T. P. (Torsten P.); Scheidenberger, C. (Christoph); Shishkin, V. (Vladimir); Stadlman, J. (Jens); Steck, M. (Markus); Vieira, D. J. (David J.); Weick, H. (Helmut); Winkler, M. (Martin); Wollnik, Hermann; Yamaguchi, T. (Takayuki)

    2004-01-01

    Recently, much progress has been made with stored exotic nuclei at relativistic velocities v/c = 0.7. Fragments of {sup 208}Pb and {sup 209}Bi projectiles and fission fragments from {sup 238}U ions have been produced, separated in flight with the fragment separator FRS, and injected into the storage-cooler ring ESR for precision measurements. Precise masses of neutron-deficient isotopes in the lead region have been measured with time-resolved Schottky Mass Spectrometry (SMS). A new isospin dependence of the pairing energy was observed due to the improved mass accuracy of typical 1.5 x 10{sup -7} (30 keV). New masses of short-lived neutron-rich fission fragments have been obtained with Isochronous Mass Spectrometry (IMS). An innovative field of spectroscopy has been opened up with lifetime measurements of stored bare and few-electron fragments after applying both stochastic and electron cooling.

  11. Symmetries and nuclei

    International Nuclear Information System (INIS)

    Henley, E.M.

    1987-01-01

    Nuclei are very useful for testing symmetries, and for studies of symmetry breaking. This thesis is illustrated for two improper space-time transformations, parity and time-reversal and for one internal symmetry: charge symmetry and independence. Recent progress and present interest is reviewed. 23 refs., 8 figs., 2 tabs

  12. Electroweak interactions in nuclei

    International Nuclear Information System (INIS)

    Henley, E.M.

    1984-06-01

    Topics include: introduction to electroweak theory; the Weinberg-Salam theory for leptons; the Weinberg-Salam theory for hadrons-the GIM mechanism; electron scattering as a probe of the electroweak interaction (observation of PV, the weak interaction for nucleons, and parity violation in atoms); and time reversed invariance and electric dipole moments of nucleons, nuclei, and atoms. 52 references

  13. Transfer involving deformed nuclei

    International Nuclear Information System (INIS)

    Rasmussen, J.O.; Guidry, M.W.; Canto, L.F.

    1985-03-01

    Results are reviewed of 1- and 2-neutron transfer reactions at near-barrier energies for deformed nuclei. Rotational angular momentum and excitation patterns are examined. A strong tendency to populating high spin states within a few MeV of the yrast line is noted, and it is interpreted as preferential transfer to rotation-aligned states. 16 refs., 12 figs

  14. Collisions with nuclei

    International Nuclear Information System (INIS)

    Gulamov, K.G.

    1987-01-01

    It is well known that interactions of high energy particles with nuclei, owing to possible intranuclear rescatterings, may provide information about the space-time behaviour of the production process. Therefore the main goals of these investigations are related with the attempts to study the space-time process of hadronization of coloured quarks and gluons produced at the initial stage of an interaction to white final state particles and to clarify the influence of composite quark-gluon structure of both the projectile and target on features of the production mechanisms. Since in both the initial and final states of these reactions the authors have strongly interacting multiparticle systems, it is of importance to study the collective properties of these systems. The questions to the point are: what is the degree of collectivization of particles newly produced in collisions with nuclei and what is the influence of the collective nature of a nucleus itself on the production mechanisms, in particular, what are the manifestations of possible multinucleon (multiquark) configurations in nuclei? It is obvious that the reductability of, say, hadron-nucleus (hA) interaction to hadron-nucleon (hN) collisions is directly related to the above problems. Due to time limitations the author discusses here only a few aspects of low p/sub t/ hA interactions which in his opinion are of importance for better understanding of general regularities of collisions with nuclei and for further investigations of the above problems

  15. Nucleons in nuclei (II)

    International Nuclear Information System (INIS)

    Laget, J.M.

    1988-01-01

    This summary is a review of our understanding of nuclei in terms of hadrons exchanging mesons. The open problems are: the determination of the high momentum components of nuclear systems, the role of the three-body forces and the nature of the short range correlations. The ways of studying these problems are discussed

  16. Electromagnetic structure of nuclei

    International Nuclear Information System (INIS)

    Arnold, R.G.

    1986-07-01

    A brief review is given of selected topics in the electromagnetic structure of nucleons and nuclei, including nucleon form factors from both quantum chromodynamics and electron scattering data, measurements of the deuteron and triton form factors, quasi-elastic scattering, and the EMC effect. 47 refs., 13 figs

  17. Rotational motion in nuclei

    International Nuclear Information System (INIS)

    Bohr, A.

    1977-01-01

    History is surveyed of the development of the theory of rotational states in nuclei. The situation in the 40's when ideas formed of the collective states of a nucleus is evoked. The general rotation theory and the relation between the single-particle and rotational motion are briefly discussed. Future prospects of the rotation theory development are indicated. (I.W.)

  18. Mesons and light nuclei

    International Nuclear Information System (INIS)

    Truhlik, E.; Mach, R.

    1992-01-01

    62 papers and one summary talk were presented at the conference, on subject matters in between nuclear physics (mainly light nuclei) and elementary particle physics, as indicated by the session headings (1) Electroweak nuclear interaction (2) Nuclear physics with pions and antiprotons (3) Nuclear physics with strange particles (4) Relativistic nuclear physics (5) Quark degrees of freedom. (Quittner)

  19. Radii of radioactive nuclei

    International Nuclear Information System (INIS)

    Mittig, W.; Plagnol, E.; Schutz, Y.

    1989-11-01

    A new simple direct method for the measurement of the total reaction cross section (σ R ) for several light radioactive nuclei (A≤40) is developed. From that, the reduced strong absorption radii (r o 2 ) are obtained. A comparison is made with data obtained by other techniques. A strong isospin dependence of the nuclear radii is observed. (L.C.) [pt

  20. Alpha clustering in nuclei

    International Nuclear Information System (INIS)

    Hodgson, P.E.

    1990-01-01

    The effects of nucleon clustering in nuclei are described, with reference to both nuclear structure and nuclear reactions, and the advantages of using the cluster formalism to describe a range of phenomena are discussed. It is shown that bound and scattering alpha-particle states can be described in a unified way using an energy-dependent alpha-nucleus potential. (author)

  1. Particles, imaging and nuclei

    International Nuclear Information System (INIS)

    Harris, J.

    1986-01-01

    The book on particles, imaging and nuclei is one of the Background Readers for the Revised Nuffield Advanced Physics course. The contents contain five educational articles, which extend concepts covered in the course and examine recent developments in physics. Four of the articles on:- particles and the forces of nature, radioisotopes, lasers probe the atomic nucleus, and nuclear history, are indexed separately. (UK)

  2. Relationship between hot spot residues and ligand binding hot spots in protein-protein interfaces.

    Science.gov (United States)

    Zerbe, Brandon S; Hall, David R; Vajda, Sandor; Whitty, Adrian; Kozakov, Dima

    2012-08-27

    In the context of protein-protein interactions, the term "hot spot" refers to a residue or cluster of residues that makes a major contribution to the binding free energy, as determined by alanine scanning mutagenesis. In contrast, in pharmaceutical research, a hot spot is a site on a target protein that has high propensity for ligand binding and hence is potentially important for drug discovery. Here we examine the relationship between these two hot spot concepts by comparing alanine scanning data for a set of 15 proteins with results from mapping the protein surfaces for sites that can bind fragment-sized small molecules. We find the two types of hot spots are largely complementary; the residues protruding into hot spot regions identified by computational mapping or experimental fragment screening are almost always themselves hot spot residues as defined by alanine scanning experiments. Conversely, a residue that is found by alanine scanning to contribute little to binding rarely interacts with hot spot regions on the partner protein identified by fragment mapping. In spite of the strong correlation between the two hot spot concepts, they fundamentally differ, however. In particular, while identification of a hot spot by alanine scanning establishes the potential to generate substantial interaction energy with a binding partner, there are additional topological requirements to be a hot spot for small molecule binding. Hence, only a minority of hot spots identified by alanine scanning represent sites that are potentially useful for small inhibitor binding, and it is this subset that is identified by experimental or computational fragment screening.

  3. Isotope shifts in unstable nuclei

    International Nuclear Information System (INIS)

    Rebel, H.

    1980-05-01

    Current experimental investigations of isotope shifts in atomic spectra of unstable nuclei and the resulting information about size and shape of nuclei far off stability are discussed with reference to some representative examples. (orig.)

  4. From nuclei to nucleons

    International Nuclear Information System (INIS)

    Scott, D.K.

    1978-03-01

    Some initial experiments in the intermediate energy region between 10 and 200 MeV/nucleon, which is largely unexplored and poorly understood is considered as regards some initial experiments in this energy region. Included are the emission of complex fragments, localization in heavy ion reactions, coincidence experiments between light and heavy fragments, and the emission of light particles in heavy ion collisions. Some initial results in the region between 20 and 100 MeV/nucleon are presented. 41 references

  5. Nuclear-charge polarization at scission in fission from moderately excited light-actinide nuclei

    International Nuclear Information System (INIS)

    Nishinaka, Ichiro

    2009-01-01

    Fragment mass yields and the average neutron multiplicity in the proton-induced fission of 232 Th and 238 U were measured by a double time-of-flight method. The most probable charges of secondary fragments were evaluated from the fragment mass yields measured by the double time-of-flight method and the fractional cumulative and independent yields reported in literature. The nuclear-charge polarization of primary fragments at scission was obtained by correcting the most probable charge of secondary fragments for neutron evaporation. The results show that the nuclear-charge polarization at scission is associated with the liquid-drop properties of nuclei and the proton shell effect with Z = 50 of heavy fragments and that it is practically insensitive to mass and excitation energy of the fissioning nucleus in the region of light-actinide nuclei. (author)

  6. Energetic Nuclei, Superdensity and Biomedicine

    Science.gov (United States)

    Baldin, A. M.

    1977-01-01

    High-energy, relativistic nuclei were first observed in cosmic rays. Studing these nuclei has provided an opportunity for analyzing the composition of cosmic rays and for experimentally verifying principles governing the behavior of nuclear matter at high and super-high temperatures. Medical research using accelerated nuclei is suggested.…

  7. KEWPIE: a dynamical cascade code for decaying exited compound nuclei

    OpenAIRE

    Bouriquet, Bertrand; Abe, Yasuhisa; Boilley, David

    2003-01-01

    A new dynamical cascade code for decaying hot nuclei is proposed and specially adapted to the synthesis of super-heavy nuclei. For such a case, the interesting channel is the tiny fraction that will decay through particles emission, thus the code avoids classical Monte-Carlo methods and proposes a new numerical scheme. The time dependence is explicitely taken into account in order to cope with the fact that fission decay rate might not be constant. The code allows to evaluate both statistical...

  8. KEWPIE: A dynamical cascade code for decaying exited compound nuclei

    Science.gov (United States)

    Bouriquet, Bertrand; Abe, Yasuhisa; Boilley, David

    2004-05-01

    A new dynamical cascade code for decaying hot nuclei is proposed and specially adapted to the synthesis of super-heavy nuclei. For such a case, the interesting channel is of the tiny fraction that will decay through particles emission, thus the code avoids classical Monte-Carlo methods and proposes a new numerical scheme. The time dependence is explicitely taken into account in order to cope with the fact that fission decay rate might not be constant. The code allows to evaluate both statistical and dynamical observables. Results are successfully compared to experimental data.

  9. Interactions of 82Pb208 nuclei with energy 158 GeV per nucleon with photoemulsion nuclei

    International Nuclear Information System (INIS)

    Adamovich, M.I.; Andreeva, N.P.; Bubnov, V.I.; Gajtinov, A.Sh.; Kanygina, Eh.K.; Musaeva, A.K.; Sejtimbetov, A.M.; Skorobagatova, V.I.; Filippova, L.N.; Chasnikov, I.Ya.

    1999-01-01

    In this report there are experimental data on 82 Pb 208 nuclei (158 GeV) interaction with photoemulsion nuclei. The said data are compared to the similar ones for 79 Au 197 nuclei with less energy (10,7 A GeV). Stack of nuclear emulsion was irradiated with the beam of nuclei 82 Pb 208 at SPS of CERN. Events search was done along the primary nucleus trace. Pb nucleus average path length happened to be λ=(3,8±0,1) cm, this virtually coincides with the one calculated by Brandt and Peters formula (3,9 cm). Secondary particles were identified into s (storm), g (knock-on protons) and b- particles (target nucleus fragments), as well as into nucleus-bullet fragments with different charges (Z=1,2,≥3). This allowed obtaining event distribution by multiplicity of these particles (n s , n g , n b ) and fragments (n z=1,2,≥3 ), calculation of average values by multiplicity (see table), finding correlation of characteristics. >From the table it's clear that when the energy increases s > increases 2,5 times where as g > insignificantly decreases and b > doesn't change

  10. Particle structure function and subbarrier fusion in hot nuclei

    International Nuclear Information System (INIS)

    Moretto, L.G.; Jing, K.X.; Phair, L.; Wozniak, G.J.

    1997-02-01

    The study of particle evaporation spectra can provide information about shape polarization phenomena induced by the nascent particle on the residual nucleus, and about optical modulations felt by the particle as it is preformed inside the nucleus. These aspects can be studied as a function temperature. Preliminary experimental evidence about these features has been obtained

  11. Calculation of the radii of neutron rich light exotic nuclei

    International Nuclear Information System (INIS)

    Charagi, S.K.; Gupta, S.K.

    1991-01-01

    The interaction cross section of a few unstable neutron rich nuclei have been measured using exotic isotope beams produced through the projectile fragmentation process in high energy heavy-ion collisions. Interaction cross section of He, Li, Be and B isotope projectiles with Be, C and Al targets have thus been measured at 790 MeV/nucleon. We have made a comprehensive analysis of the data on the interaction cross section, to extract the radii of these neutron rich light nuclei. 7 refs., 1 fig., 3 tabs

  12. Role of ternary fission in synthesis of bypassed nuclei

    International Nuclear Information System (INIS)

    Kramarovskij, Ya.M.; Chechev, V.P.

    1983-01-01

    A possible influence of ternary fission with escape of neutron-enriched light charged particles on the synthesis of bypassed nuclides is considered. It is shown that this concept cannot give explanation of bypassed isotope concentrations, but it can make some contribution, if the probability of ternary fission for superheavy nuclei grows sharply with Z 2 /A parameter. The account of β-delayed fission contributes to the shift of ternary fission fragments into the region of neutron-deficient isotopes. Consistent consideration of the ternary fission role in the nucleosynthesis is possible only with an important accumulation of experimental and theoretical data on this process, particularly for the nuclei with Z > 100

  13. Fragment mass distribution of proton-induced spallation reaction with intermediate energy

    International Nuclear Information System (INIS)

    Fan Sheng; Ye Yanlin; Xu Chuncheng; Chen Tao; Sobolevsky, N.M.

    2000-01-01

    The test of part benchmark of SHIELD code is finished. The fragment cross section and mass distribution and excitation function of the residual nuclei from proton-induced spallation reaction on thin Pb target with intermediate energy have been calculated by SHIELD code. And the results are in good agreement with measured data. The fragment mass distribution of the residual nuclei from proton-induced spallation reaction on thick Pb target with incident energy 1.6 GeV have been simulated

  14. HOT 2017

    DEFF Research Database (Denmark)

    Hannibal, Sara Stefansen

    HOT er en kvalitativ undersøgelse, der hvert år diskuterer og undersøger en lille udvalgt skare af danskkyndige fagpersoners bud på, hvad de er optagede af på literacyområdet her og nu – altså hvilke emner, de vil vurdere som aktuelle at forholde sig til i deres nuværende praksis.......HOT er en kvalitativ undersøgelse, der hvert år diskuterer og undersøger en lille udvalgt skare af danskkyndige fagpersoners bud på, hvad de er optagede af på literacyområdet her og nu – altså hvilke emner, de vil vurdere som aktuelle at forholde sig til i deres nuværende praksis....

  15. Disintegration of comet nuclei

    International Nuclear Information System (INIS)

    Ksanfomality, Leonid V

    2012-01-01

    The breaking up of comets into separate pieces, each with its own tail, was seen many times by astronomers of the past. The phenomenon was in sharp contrast to the idea of the eternal and unchangeable celestial firmament and was commonly believed to be an omen of impending disaster, especially for comets with tails stretching across half the sky. It is only now that we have efficient enough space exploration tools to see comet nuclei and even - in the particular case of small comet Hartley-2 in 2010 - to watch their disintegration stage. There are also other suspected candidates for disintegration in the vast family of comet nuclei and other Solar System bodies. (physics of our days)

  16. Pions scatter by nuclei

    International Nuclear Information System (INIS)

    Huefner, J.

    1975-01-01

    Are pions a good tool to study nuclei. If the emphasis of this question rests on ''tool'', the answer must be ''not yet.'' The reason: one does not even understand how a pion interacts with a nucleus. This is part of the many-body problem for strongly interacting particles and its study is a basic problem in physics. One must investigate questions like: Can one understand pion-nucleus interactions from pion-nucleon physics. How does a Δ-resonance look in nuclei. Once one has solved those basic problems, there will be spinoffs in medical, technical and nuclear areas. Then pions can be used as a tool to study nuclear properties

  17. Chaos in collective nuclei

    International Nuclear Information System (INIS)

    Whelan, N.D.

    1993-01-01

    Random Matrix Theory successfully describes the statistics of the low-lying spectra of some nuclei but not of others. It is currently believed that this theory applies to systems in which the corresponding classical motion is chaotic. This conjecture is tested for collective nuclei by studying the Interacting Boson Model. Quantum and classical measures of chaos are proposed and found to be in agreement throughout the parameter space of the model. For some parameter values the measures indicate the presence of a previously unknown approximate symmetry. A phenomenon called partial dynamical symmetry is explored and shown to lead to a suppression of chaos. A time dependent function calculated from the quantum spectrum is discussed. This function is sensitive to the extent of chaos and provides a robust method of analyzing experimental spectra

  18. Chaotic behavior in nuclei

    International Nuclear Information System (INIS)

    Mitchel, G.; Shriner, J.

    2005-01-01

    Although the predictions of Random Matrix Theory (RMT) were available by the early 1960s, data of sufficiently high quality to adequately test the theory were only obtained a decade later by Rainwater. It was another decade later that Bohigas, Haq and Pandey combined the best available nuclear resonance data - the Columbia neutron resonances in heavy nuclei and the TUNL proton resonances in lighter nuclei - to form the Nuclear Data Ensemble. They obtained excellent agreement for the level statistics with the RMT predictions. The expected Porter-Thomas (PT) distribution was considered very early. However, since the widths (amplitudes squared) are measured, the predicted Gaussian distribution for the amplitudes was only qualitatively confirmed. A much more sensitive test was performed by measuring two widths and the relative phase between the two amplitudes. By comparison of the width and amplitude correlations, the Gaussian distribution was confirmed at the 1% level. Following the Bohigas conjecture - that quantum analogs of classically chaotic systems obey RMT - there was an explosion of activity utilizing level statistics in many different quantum systems. In nuclei the focus was verifying the range of applicability of RMT. Of particular interest was the effect of collectivity and of excitation energy on statistical properties. The effect of symmetry breaking on level statistics was examined and early predictions by Dyson were confirmed. The effect of symmetry breaking on the width distribution was also measured for the first time. Although heuristic arguments predicted no change from the PT distribution, experimentally there was a large deviation from the PT prediction. Later theoretical efforts were consistent with this result. The stringent conditions placed on the experiments - for eigenvalue tests the data need to be essentially perfect (few or no missing levels or mis assigned quantum numbers) - has limited the amount of suitable experimental data. The

  19. Dynamic effects in fragmentation reactions

    International Nuclear Information System (INIS)

    Bertsch, G. F.; Esbensen, H.

    2002-01-01

    Fragmentation reactions offer a useful tool to study the spectroscopy of halo nuclei, but the large extent of the halo wave function makes the reaction theory more difficult. The simple reaction models based on the eikonal approximation for the nuclear interaction or first-order perturbation theory for the Coulomb interaction have systematic errors that they investigate here, comparing to the predictions of complete dynamical calculations. They find that stripping probabilities are underpredicted by the eikonal model, leading to extracted spectroscopy strengths that are two large. In contrast, the Coulomb excitation is overpredicted by the simple theory. They attribute this to a screening effect, as is well known in the Barkas effect on stopping powers. The errors decrease with beam energy as E(sub beam)(sup -1), and are not significant at beam energies above 50 MeV/u. At lower beam energies, the effects should be taken into account when extracting quantitative spectroscopic strengths

  20. Hot particles

    International Nuclear Information System (INIS)

    Merwin, S.E.; Moeller, M.P.

    1989-01-01

    Nuclear Regulatory Commission (NRC) licensees are required to assess the dose to skin from a hot particle contamination event at a depth of skin of7mg/cm 2 over an area of 1 cm 2 and compare the value to the current dose limit for the skin. Although the resulting number is interesting from a comparative standpoint and can be used to predict local skin reactions, comparison of the number to existing limits based on uniform exposures is inappropriate. Most incidents that can be classified as overexposures based on this interpretation of dose actually have no effect on the health of the worker. As a result, resources are expended to reduce the likelihood that an overexposure event will occur when they could be directed toward eliminating the cause of the problem or enhancing existing programs such as contamination control. Furthermore, from a risk standpoint, this practice is not ALARA because some workers receive whole body doses in order to minimize the occurrence of hot particle skin contaminations. In this paper the authors suggest an alternative approach to controlling hot particle exposures

  1. Structures of exotic nuclei

    International Nuclear Information System (INIS)

    Hamilton, J.H.

    1987-01-01

    Discoveries of many different types of nuclear shape coexistence are being found at both low and high excitation energies throughout the periodic table, as documented in recent reviews. Many new types of shape coexistence have been observed at low excitation energies, for examples bands on more than four different overlapping and coexisting shapes are observed in 185 Au, and competing triaxial and prolate shapes in 71 Se and 176 Pt. Discrete states in super-deformed bands with deformations β 2 ∼ 0.4-0.6, coexisting with other shapes, have been seen to high spin up to 60ℎ in 152 Dy, 132 Ce and 135 Nd. Super-deformed nuclei with N and Z both around 38 and around Z = 38, N ≥ 60. These data led to the discovery of new shell gaps and magic numbers of 38 for N and Z and 60 for N but now for deformed shapes. Marked differences in structure are observed at spins of 6 to 20 in nuclei in this region, which differ by only two protons; for example, 68 Ge and 70 Se. The differences are thought to be related to the competing shell gaps in these nuclei

  2. Elusive active galactic nuclei

    Science.gov (United States)

    Maiolino, R.; Comastri, A.; Gilli, R.; Nagar, N. M.; Bianchi, S.; Böker, T.; Colbert, E.; Krabbe, A.; Marconi, A.; Matt, G.; Salvati, M.

    2003-10-01

    A fraction of active galactic nuclei do not show the classical Seyfert-type signatures in their optical spectra, i.e. they are optically `elusive'. X-ray observations are an optimal tool to identify this class of objects. We combine new Chandra observations with archival X-ray data in order to obtain a first estimate of the fraction of elusive active galactic nuclei (AGN) in local galaxies and to constrain their nature. Our results suggest that elusive AGN have a local density comparable to or even higher than optically classified Seyfert nuclei. Most elusive AGN are heavily absorbed in the X-rays, with gas column densities exceeding 1024 cm-2, suggesting that their peculiar nature is associated with obscuration. It is likely that in elusive AGN the nuclear UV source is completely embedded and the ionizing photons cannot escape, which prevents the formation of a classical narrow-line region. Elusive AGN may contribute significantly to the 30-keV bump of the X-ray background.

  3. Fast helium production in interactions of 3.7 A GeV 24Mg with emulsion nuclei

    International Nuclear Information System (INIS)

    Jilany, M.A.

    2004-01-01

    We have studied the properties of the relativistic helium fragments emitted from the projectile in the interactions of 24 Mg ions accelerated at an energy of 3.7 A GeV with emulsion nuclei. The total, partial nuclear cross-sections and production rates of helium fragmentation channels in relativistic nucleus-nucleus collisions and their dependence on the mass and energy of the incident projectile nucleus are investigated. The yields of multiple helium projectile fragments disrupted from the interactions of 24 Mg projectile nuclei with hydrogen H, light CNO and heavy AgBr groups of target emulsion nuclei are discussed and they indicate that the breakup mechanism of the projectile seems to be independent of the target mass. Limiting fragmentation behavior of fast-moving helium fragments is observed in both the projectile and target nuclei. The multiplicity distributions of helium projectile fragments emitted in the interactions of 24 Mg projectile nuclei with the different target nuclei of the emulsion are well described by the KNO scaling presentation. The mean multiplicities of the different charged secondary particles, normally defined shower, grey and black (left angle n s right angle, left angle n g right angle and left angle n b right angle) emitted in the interactions of 3.7 A GeV 24 Mg with the different groups of emulsion nuclei at different ranges of projectile fragments are decreasing when the number of He fragments stripped from projectile increases. These values of left angle n i right angle (i=s, g, band h particles) in the events where the emission of fast helium fragments were accompanied by heavy fragments having Z≥3 seem to be constant as the He multiplicity increases, and exhibit a behavior independent of the He multiplicity. (orig.)

  4. On the nuclear fragmentation mechanisms in nuclear collisions at intermediate and high energies

    International Nuclear Information System (INIS)

    Jipa, Al.; Besliu, C.; Felea, D.; Iliescu, B.; Ristea, O.; Ristea, M.; Calin, C.; Horbuniev, A.; Arsene, I.; Esanu, T.; Ochesanu, S.; Caramarcu, C.; Bordeianu, C.; Rosu, I.; Grossu, V.; Zgura, I.S.; Stan, E.; Mitu, C.; Potlog, M.; Cherciu, M.; Stefan, I.

    2004-01-01

    The nuclear fragmentation mechanisms can be discussed taking into account different scales. These scales are related to the fragment sizes. Taking into account the possible different fragmentation mechanisms of the nuclei at the same incident energy an analysis of the experimental results obtained in different experiments performed at the JINR Dubna (Russia), KEK Tsukuba (Japan), GSI Darmstadt (Germany) is done. Results on apparent temperatures, angular distributions, fragment momentum spectra, multiplicities of the intermediate mass fragments are used to analyse the competition between two possible nuclear fragmentation mechanisms, namely: a sudden fragmentation by explosive mechanisms, like shock waves, and a slow fragmentation by the 'fission' of the spectator regions, mainly, because of the interactions with the particles or fragments emitted from the participant region at transverse angles on the incident nucleus, in CMS.Some connections with chaos dynamics and fractal structure of the fragmentation patterns are included. (authors)

  5. Study of the experimental data of multifragmentation of gold and krypton nuclei on interactions with photoemulsion nuclei at high energies

    International Nuclear Information System (INIS)

    Saleh, Z.A.; Abdel-Hafez, A.

    2002-01-01

    Results from EMU-01/12 collaboration for the experimental data on multifragmentation of gold residual nuclei created in the interactions with photoemulsion nuclei at the energy of 10.7 GeV/nucleon are presented together with the experimental data on multifragmentation of krypton created on the interactions with photoemulsion nuclei at energy of 0.9 GeV/nucleon. The data are analyzed in the frame of the statistical model of multifragmentation. It is obvious that there are two regimes for nuclear multifragmentation: the former is when less than one-half of nucleons of projectile nucleus are knocked out, the later is when more than one-half of nucleons are knocked out. Residual nuclei with masses close to each other created at different reactions are fragmented practically simultaneously when more than one-half of nucleons of original nuclei are knocked out. These results give an indication that projectiles other than Gold and Krypton may give the same characterization on interaction with emulsion nuclei at high energies

  6. Lack of incorporation of tritiated uridine by nuclei of mature sieve elements in Metasequoia glyptostroboides and Sequoiadendron giganteum.

    Science.gov (United States)

    Hébant, C

    1975-01-01

    The majority of nuclei which persist in "mature" sieve elements of Metasequoia glyptostroboides Hu and Chen and Sequoiadendron giganteum Buchholz fail to incorporate tritiated uridine (10 μCi/ml; 7 hours incubation of stem fragments). This is interpreted as further evidence for the degenerated condition of these nuclei.

  7. Parton Propagation and Fragmentation in QCD Matter

    Energy Technology Data Exchange (ETDEWEB)

    Alberto Accardi, Francois Arleo, William Brooks, David D' Enterria, Valeria Muccifora

    2009-12-01

    We review recent progress in the study of parton propagation, interaction and fragmentation in both cold and hot strongly interacting matter. Experimental highlights on high-energy hadron production in deep inelastic lepton-nucleus scattering, proton-nucleus and heavy-ion collisions, as well as Drell-Yan processes in hadron-nucleus collisions are presented. The existing theoretical frameworks for describing the in-medium interaction of energetic partons and the space-time evolution of their fragmentation into hadrons are discussed and confronted to experimental data. We conclude with a list of theoretical and experimental open issues, and a brief description of future relevant experiments and facilities.

  8. Particles and nuclei, letters

    International Nuclear Information System (INIS)

    2001-01-01

    The present collection of letters from JINR, Dubna, contains eight separate records on the interaction of high energy Λ 6 He hypernuclear beams with atomic nuclei, the position-sensitive detector of a high spatial resolution on the basis of a multiwire gas electron multiplier, pseudorapidity hadron density at the LHC energy, high precision laser control of the ATLAS tile-calorimeter module mass production at JINR, a new approach to ECG's features recognition involving neural network, subcriticity of a uranium target enriched in 235 U, beam space charge effects in high-current cyclotron injector CI-5, a homogeneous static gravitational field and the principle of equivalence

  9. Active galactic nuclei

    CERN Document Server

    Beckmann, Volker

    2012-01-01

    This AGN textbook includes phenomena based on new results in the X-Ray domain from new telescopes such as Chandra and XMM Newton not mentioned in any other book. Furthermore, it considers also the Fermi Gamma Ray Space Telescope with its revolutionary advances of unprecedented sensitivity, field of view and all-sky monitoring. Those and other new developments as well as simulations of AGN merging events and formations, enabled through latest super-computing capabilities. The book gives an overview on the current knowledge of the Active Galacitc Nuclei phenomenon. The spectral energy d

  10. Elementary excitations in nuclei

    International Nuclear Information System (INIS)

    Lemmer, R.H.

    1987-01-01

    The role of elementary quasi-particle and quasi-hole excitations is reviewed in connection with the analysis of data involving high-lying nuclear states. This article includes discussions on: (i) single quasi-hole excitations in pick-up reactions, (ii) the formation of single quasi-hole and quasi-particle excitations (in different nuclei) during transfer reactions, followed by (iii) quasi-particle quasi-hole excitations in the same nucleus that are produced by photon absorption. Finally, the question of photon absorption in the vicinity of the elementary Δ resonance is discussed, where nucleonic as well as nuclear degrees of freedom can be excited

  11. Particles and nuclei, letters

    International Nuclear Information System (INIS)

    2000-01-01

    The present collection of letters from JINR, Dubna, contains six separate records on the DELPHI experiment at LEP, the Fermi-surface dynamics of rotating nuclei, production of large samples of the silica dioxide aerogel in the 37-litre autoclave and test of its optical properties, preliminary radiation resource results on scintillating fibers, a new algorithm for the direct transformation method of time to digital with the high time resolution and development and design of analogue read-out electronics for HADES drift chamber system

  12. Active galactic nuclei

    CERN Document Server

    Blandford, RD; Woltjer, L

    1990-01-01

    Starting with this volume, the Lecture Notes of the renowned Advanced Courses of the Swiss Society for Astrophysics and Astronomy will be published annually. In each course, three extensive lectures given by leading experts in their respective fields cover different and essential aspects of the subject. The 20th course, held at Les Diablerets in April 1990, dealt with current research on active galactic nuclei; it represents the most up-to-date views on the subject, presented with particular regard for clarity. The previous courses considered a wide variety of subjects, beginning with ""Theory

  13. Close collisions between light nuclei: Orbiting and fusion

    International Nuclear Information System (INIS)

    Shapira, D.; Shivakumar, B.; Harmon, B.A.; Ayik, S.

    1987-01-01

    Our data have demonstrated that in close collisions the two nuclei first form a rotating dinuclear complex (DNC) which can break up into two complex fragments (Orbiting) or evolve into a compound nucleus. The binary fragment yield was found to be significant in contradiction with earlier views which held that whenever nucleus-nucleus capture occurs fusion is a certainty. The time duration of the dinuclear stage and the nature of its evolution into a compound nucleus were studied and a model which describes these processes will be presented. 25 refs., 14 figs

  14. Fission mass yields of excited medium heavy nuclei

    International Nuclear Information System (INIS)

    Sandulescu, A.; Depta, K.; Herrmann, R.; Greiner, W.; Scheid, W.

    1985-01-01

    The mass distributions resulting from the fission of excited medium mass nuclei are discussed on the basis of the fragmentation theory. It is shown that very asymmetric fission events can be expected with rates which are only a few orders of magnitude smaller than the rates for symmetric fission. As an example a calculation of the fission mass distribution of the excited 172 Yb compound nucleus is presented. This mass distribution reveals observable structures over the entire range of the mass asymmetry due to valleys in the potential energy surface for fission fragments with closed proton and neutron shells

  15. The Initial Stages of Colliding Nuclei and Hadrons

    International Nuclear Information System (INIS)

    Tribedy, Prithwish

    2017-01-01

    The final day of the Hot Quarks 2016 conference was focused on the discussions of the initial stages of colliding nuclei and hadrons. In this conference proceedings we give a brief overview of a few selective topics discussed at the conference that include latest developments in the theoretical description of the initial state towards understanding a number of recent experimental results from RHIC and LHC. (paper)

  16. Superfluidity of nuclei and the nucleon--phonon interaction

    International Nuclear Information System (INIS)

    Kadmenskii, S.G.; Luk'yanovich, P.A.

    1989-01-01

    The Lehmann expansion for the exact one-particle Green function in a system with superfluidity is obtained. Expressions for the correlation function and mass operator are derived with allowance for a retarded nucleon--phonon interaction. Within the scope of the formalism developed, equations for the superfluidity of nuclei allowing for quasiparticle fragmentation effects are derived. It is concluded that the retarded nucleon--phonon interaction in the particle--particle channel causes a decrease of the fragmentation of the one-particle force in the vicinity of the Fermi surface. It is shown that inclusion of a nonretarded vacuum interaction of two nucleons and of a retarded interaction due to the exchange between two nucleons of low-lying highly collectivized quadrupole phonons is sufficient to provide the necessary scale of attraction in the description of pair correlations of nucleons in nuclei with developed superfluidity

  17. Decay properties of nuclei in the neighbourhood of 100Sn

    International Nuclear Information System (INIS)

    Straub, Katrin

    2011-01-01

    This thesis concentrates on nuclear properties of very neutron deficient nuclei near the proton dripline in the neighbourhood of doubly-magic 100 Sn. In an experiment performed in March 2008 at the GSI in Darmstadt, the exotic nuclei were produced in a projectile fragmentation reaction using a 124 Xe primary beam with an energy of 100 AMeV impinging on a 4000 Beryllium target, separated and identified in the FRS and eventually stopped for decay spectroscopy in a complex implantation detector developed at the institute E12. The Germanium array RISING was employed for the measurement of prompt and delayed gamma radiation. Production cross sections and half lives were determined along the proton dripline. The isotopes 99 Sn, 97 In and 95 Cd were identified for the first time. additional nuclei studied in this thesis are 103 Sn, 96 Cd as well as the two tin isotopes 101 Sn and 102 Sn. (orig.)

  18. Aspects of data on the breakup of highly excited nuclei

    International Nuclear Information System (INIS)

    Warwick, A.I.; Wieman, H.H.; Gutbrod, H.H.; Ritter, H.G.; Stelzer, H.; Weik, F.; Kaufman, S.B.; Steinberg, E.P.; Wilkins, B.D.

    1983-05-01

    There is an awakening of theoretical interest in the mechanisms by which nuclear fragments (4 less than or equal to A less than or equal to 150) are produced in violent collisions of heavy ions. With this in mind we review some aspects of the available experimental data and point out some challenging features against which to test the models. The concept of evaporation is tremendously powerful when applied to pieces of nuclei of low excitation (1 or 2 MeV/u). Current interest focuses on higher excitations, at the point where the binding energy of the system vanishes. This is the transition from liquid nuclei to a gas of nucleons, and it may be that the critical phenomena that certainly exist in infinite nuclear matter will be manifest in finite nuclei under these conditions

  19. Measurement of proton capture reactions in the hot cycles: an evaluation of experimental methods

    Energy Technology Data Exchange (ETDEWEB)

    Leleux, P [Inst. de Physique Nucleaire, Univ. Catholique de Louvain, Louvain-la-Neuve (Belgium)

    1998-06-01

    In the hot cycles, most of the proton capture reactions involve radioactive nuclei in the entrance and exit channels. This paper evaluates the specific methods that were designed to measure such reactions. (orig.)

  20. Exotic nuclei and radioactive beams

    International Nuclear Information System (INIS)

    Chomaz, P.

    1996-01-01

    The Nuclei called exotic are all the nuclei that it is necessary to recreate in laboratory to study them. Their life time is too short -in relation to earth age- for it remains enough on earth. The researchers are going to have at their s disposal at GANIL (Caen) with the S.P.I.R.A.L. project, exotic nuclei beams and will study new kinds of nuclear reactions to better understand the atom nucleus. (N.C.). 2 refs., 9 figs

  1. Isolation of Nuclei and Nucleoli.

    Science.gov (United States)

    Pendle, Alison F; Shaw, Peter J

    2017-01-01

    Here we describe methods for producing nuclei from Arabidopsis suspension cultures or root tips of Arabidopsis, wheat, or pea. These methods could be adapted for other species and cell types. The resulting nuclei can be further purified for use in biochemical or proteomic studies, or can be used for microscopy. We also describe how the nuclei can be used to obtain a preparation of nucleoli.

  2. Universal elements of fragmentation

    International Nuclear Information System (INIS)

    Yanovsky, V. V.; Tur, A. V.; Kuklina, O. V.

    2010-01-01

    A fragmentation theory is proposed that explains the universal asymptotic behavior of the fragment-size distribution in the large-size range, based on simple physical principles. The basic principles of the theory are the total mass conservation in a fragmentation process and a balance condition for the energy expended in increasing the surface of fragments during their breakup. A flux-based approach is used that makes it possible to supplement the basic principles and develop a minimal theory of fragmentation. Such a supplementary principle is that of decreasing fragment-volume flux with increasing energy expended in fragmentation. It is shown that the behavior of the decreasing flux is directly related to the form of a power-law fragment-size distribution. The minimal theory is used to find universal asymptotic fragment-size distributions and to develop a natural physical classification of fragmentation models. A more general, nonlinear theory of strong fragmentation is also developed. It is demonstrated that solutions to a nonlinear kinetic equation consistent with both basic principles approach a universal asymptotic size distribution. Agreement between the predicted asymptotic fragment-size distributions and experimental observations is discussed.

  3. Tunneling in decay and fusion of compound nuclei

    International Nuclear Information System (INIS)

    Tarakanov, A.V.; Shilov, V.M.

    1988-01-01

    On the basis of the multichannel boundary-condition model we demonstrate the asymmetry of the total transmission of the Coulomb barrier taking into account the internal structure of the colliding nuclei. For decay the enhancement of the tunneling probability in comparison with the single-channel case is small. We prove the importance of taking into account states in which one of the decay-product fragments is in an excited state

  4. Theory of magic nuclei

    International Nuclear Information System (INIS)

    Nosov, V.G.; Kamchatnov, A.M.

    A consistent theory of the shell and magic oscillations of the masses of spherical nuclei is developed on the basis of the Fermi liquid concept of the energy spectrum of nuclear matter. A ''magic'' relationship between the system's dimensions and the limiting momentum of the quasi-particle distribution is derived; an integer number of the de Broglie half-waves falls on the nuclear diameter. An expression for the discontinuity in the nucleon binding energy in the vicinity of a magic nucleus is obtained. The role of the residual interaction is analyzed. It is shown that the width of the Fermi-surface diffuseness due to the residual interaction is proportional to the squared vector of the quasi-particle orbital angular momentum. The values of the corresponding proportionality factors (the coupling constant for quasi particles) are determined from the experimental data for 52 magic nuclei. The rapid drop of the residual interaction with increasing nuclear size is demonstrated. (7 figures, 3 tables) (U.S.)

  5. Stability of superheavy nuclei

    Science.gov (United States)

    Pomorski, K.; Nerlo-Pomorska, B.; Bartel, J.; Schmitt, C.

    2018-03-01

    The potential-energy surfaces of an extended set of heavy and superheavy even-even nuclei with 92 ≤Z ≤126 and isospins 40 ≤N -Z ≤74 are evaluated within the recently developed Fourier shape parametrization. Ground-state and decay properties are studied for 324 different even-even isotopes in a four-dimensional deformation space, defined by nonaxiality, quadrupole, octupole, and hexadecapole degrees of freedom. Nuclear deformation energies are evaluated in the framework of the macroscopic-microscopic approach, with the Lublin-Strasbourg drop model and a Yukawa-folded mean-field potential. The evolution of the ground-state equilibrium shape (and possible isomeric, metastable states) is studied as a function of Z and N . α -decay Q values and half-lives, as well as fission-barrier heights, are deduced. In order to understand the transition from asymmetric to symmetric fission along the Fm isotopic chain, the properties of all identified fission paths are investigated. Good agreement is found with experimental data wherever available. New interesting features about the population of different fission modes for nuclei beyond Fm are predicted.

  6. Cluster structures in light nuclei

    International Nuclear Information System (INIS)

    Horiuchi, H.

    2000-01-01

    Complete text of publication follows. Clustering in neutron-rich nuclei is discussed. To understand the novel features (1,2,3) of the clustering in neutron-rich nuclei, the basic features of the clustering in stable nuclei (4) are briefly reviewed. In neutron-rich nuclei, the requirement of the stability of clusters is questioned and the threshold rule is no more obeyed. Examples of clustering in Be and B isotopes (4,5) are discussed in some detail. Possible existence of novel type of clustering near neutron dripline is suggested (1). (author)

  7. Intermittency in {sup 197}Au fragmentation

    Energy Technology Data Exchange (ETDEWEB)

    Dabrowska, A; Holynski, R; Olszewski, A; Szarska, M; Wilczynska, B; Wolter, W; Wosiek, B [Institute of Nuclear Physics, Cracow (Poland); Cherry, M L; Deines-Jones, P; Jones, W V; Sengupta, K; Wefel, B [Louisiana State Univ., Baton Rouge, LA (United States). Dept. of Physics and Astronomy; Waddington, C J [Minnesota Univ., Minneapolis, MN (United States). School of Physics and Astronomy; Pozharova, E A; Skorodko, T Yu [Inst. of Theoretical and Experimental Physics, Moscow (Russian Federation); KLMM Collaboration

    1995-07-01

    The concept of factorial moments was applied to an analysis of the dynamical fluctuations in the charge distributions of the fragments emitted from gold nuclei with energies 10.6 and < 1.0 GeV/n interacting with emulsion nuclei. Clear evidence for intermittent fluctuations has been found in an analysis using all the particles released from the gold projectile, with a stronger effect observed below 1 GeV/n than at 10.6 GeV/n. For the full data sets, however, the intermittency effect was found to be very sensitive to the singly charged particles, and neglecting these particles strongly reduces the intermittency signal. When the analysis is restricted to the multiply charged fragments, an intermittency effect is revealed only for multifragmentation events, although one that is enhanced as compared to the analysis of all, singly and multiply charged, particles. The properties of the anomalous fractal dimensions suggest a sequential decay mechanism, rather than the existence of possible critical behaviour in the process of nuclear fragmentation. The likely influence of the charge conservation effects and the finite size of decaying systems on the observed intermittency signals was pointed out. (author). 37 refs, 9 figs, 5 tabs.

  8. Nuclear fragmentation and the number of particle tracks in tissue

    International Nuclear Information System (INIS)

    Ponomarev, A. L.; Cucinotta, F. A.

    2006-01-01

    For high energy nuclei, the number of particle tracks per cell is modified by local nuclear reactions that occur, with large fluctuations expected for heavy ion tracks. Cells near the interaction site of a reaction will experience a much higher number of tracks than estimated by the average fluence. Two types of reaction products are possible and occur in coincidence; projectile fragments, which generally have smaller charge and similar velocity to that of the projectile, and target fragments, which are produced from the fragmentation of the nuclei of water atoms or other cellular constituents with low velocity. In order to understand the role of fragmentation in biological damage a new model of human tissue irradiated by heavy ions was developed. A box of the tissue is modelled with periodic boundary conditions imposed, which extrapolates the technique to macroscopic volumes of tissue. The cross sections for projectile and target fragmentation products are taken from the quantum multiple scattering fragmentation code previously developed at NASA Johnson Space Center. Statistics of fragmentation pathways occurring in a cell monolayer, as well as in a small volume of 10 x 10 x 10 cells are given. A discussion on approaches to extend the model to describe spatial distributions of inactivated or other cell damage types, as well as highly organised tissues of multiple cell types, is presented. (authors)

  9. Level structures in Yb nuclei far from stable nuclei

    International Nuclear Information System (INIS)

    Hashizume, Akira

    1982-01-01

    Applying n-γ, γ-γ coincidence techniques, the excited levels in 158 Yb and in 157 Yb nuclei were studied. Stress is placed ona neutron detection technique to assign (HI,xn) reactions which produce the nuclei far from β stability line. (author)

  10. Production of photofission fragments and study of their nuclear structure by laser spectroscopy

    International Nuclear Information System (INIS)

    Gangrskij, Yu.P.; Zemlyanoj, S.G.; Karaivanov, D.V.; Marinova, K.P.; Markov, B.N.; Mel'nikova, L.M.; Myshinskij, G.V.; Penionzhkevich, Yu.Eh.; Zhemenik, V.I.

    2005-01-01

    The prospective nuclear structure investigations of the fission fragments by resonance laser spectroscopy methods are discussed. Research in this field is currently being carried out as part of the DRIBs project, which is under development at the Laboratory of Nuclear Reactions, JINR. The fission fragments under study are mainly very neutron-rich nuclei near the proton (Z=50) and neutron (N=50 and 82) closed shells, nuclei in the region of strong deformation (N>60 and N>90) and nuclei with high-spin isomeric states. Resonance laser spectroscopy is used successfully in the study of the structure of such nuclei. It allows one to determine a number of nuclear parameters (mean-square charge radius, magnetic dipole and electric quadrupole moments) and to make conclusions about the collective and single particle properties of the nuclei

  11. Synthesis and radioactive properties of the heaviest nuclei

    International Nuclear Information System (INIS)

    Oganesyan, Yu.Ts.

    1996-01-01

    Experimental investigations on the synthesis and study of properties of faraway transactinide elements confirm the predictions of macro-microscopic theory on the existence of closed shells in the region of heavy deformed nuclei. It has been demonstrated experimentally that nuclear structure plays a decisive role in the stability of superheavy nuclides. Based on the experimental confirmation of the main provisions of the theory and after the introduction of a necessary correction into the calculation the properties of heavier nuclides in the region of spherical shells Z=114 and N=180-184 have been predicted. Here a substantial increase in the stability of nuclei is also expected. All the nuclei synthesized by now, were obtained in fusion reactions with a formation of a compound nucleus, the transition of which to the ground state takes place with the emission of neutrons and gamma-rays. Both the reactions of cold and hot fusion of nuclei can be used for the synthesis of new nuclei. Nevertheless, new experimental data on the fusion mechanism are required, since a number of theoretical descriptions of the fusion dynamics of complex nuclear systems need a substantial revising. One can assume that the reactions of the type 244 Pu, 248 Cm + 48 Ca are still within the current potential of the accelerators and experimental technique. This potential, nevertheless, is still to be implemented. 37 refs., 6 figs

  12. Electron scattering off nuclei

    International Nuclear Information System (INIS)

    Gattone, A.O.

    1989-01-01

    Two recently developed aspects related to the scattering of electrons off nuclei are presented. On the one hand, a model is introduced which emphasizes the relativistic aspects of the problem in the impulse approximation, by demanding strict maintenance of the algebra of the Poincare group. On the other hand, the second model aims at a more sophisticated description of the nuclear response in the case of collective excitations. Basically, it utilizes the RPA formalism with a new development which enables a more careful treatment of the states in the continuum as is the case for the giant resonances. Applications of both models to the description of elastic scattering, inelastic scattering to discrete levels, giant resonances and the quasi-elastic region are discussed. (Author) [es

  13. Antideuteron annihilation on nuclei

    International Nuclear Information System (INIS)

    Cugnon, J.

    1992-01-01

    An investigation of antideuteron annihilation on nuclei within an intranuclear cascade (INC) model is presented. Two models are set up to describe the annihilation itself, which either implies the antideuteron as a whole and occurs at a single point, or which may be considered as two independent nucleon-antinucleon annihilation occurring at different points and different times. Particular attention is paid to the energy transferred from the pions issued from the annihilation to the nuclear system and to the possibility of having a multifragmentation of the target. The latter feature is investigated within a percolation model. The pion distribution and the energy distribution are also discussed. Predictions of proton multiplicity distributions are compared with experiment. (orig.)

  14. Particles and nuclei, letters

    International Nuclear Information System (INIS)

    2002-01-01

    The present collection of letters from JINR, Dubna, contains ten separate records on Wien filter using in exploring on low-energy radioactive nuclei, memory effects in dissipative nucleus-nucleus collision, topological charge and topological susceptibility in connection with translation and gauge invariance, solutions of the multitime Dirac equation, the maximum entropy technique. System's statistical description, the charged conductor inside dielectric. Solution of boundary condition by means of auxiliary charges and the method of linear algebraic equations, optical constants of the TGS single crystal irradiated by power pulsed electron beam, interatomic pair potential and n-e amplitude from slow neutron scattering by noble gases, the two-coordinate multiwire proportional chamber of the high spatial resolution and neutron drip line in the region of O-Mg isotopes

  15. Particles and nuclei, letters

    International Nuclear Information System (INIS)

    2000-01-01

    The present collection of letters from JINR, Dubna, contains seven separate records on the integral representation for structure functions and target mass effects, multiscale properties of DNA primary structure including cross-scale correlations, dissipative evolution of the elementary act, the fine structure of the M T =1 Gamow-Teller resonance in 147g Tb→ 147 Gd β + /EC decay, the behaviour of the TVO temperature sensors in the magnetic fields, a fast method for searching for tracks in multilayer drift chambers of HADES spectrometer, a novel approach to particle track etching including surfactant enhanced control of pore morphology, azimuthal correlations of secondary particles in 32 S induced interactions with Ag(Br) nuclei at 4.5 GeV/ c/ nucleon

  16. Pulsars: gigantic nuclei

    International Nuclear Information System (INIS)

    Xu, Renxin

    2011-01-01

    What is the real nature of pulsars? This is essentially a question of the fundamental strong interaction between quarks at low-energy scale and hence of the non-perturbative quantum chromo-dynamics, the solution of which would certainly be meaningful for us to understand one of the seven millennium prize problems (i.e., "Yang-Mills Theory") named by the Clay Mathematical Institute. After a historical note, it is argued here that a pulsar is very similar to an extremely big nucleus, but is a little bit different from the gigantic nucleus speculated 80 years ago by L. Landau. The paper demonstrates the similarity between pulsars and gigantic nuclei from both points of view: the different manifestations of compact stars and the general behavior of the strong interaction. (author)

  17. Clusters in nuclei

    CERN Document Server

    Following the pioneering discovery of alpha clustering and of molecular resonances, the field of nuclear clustering is today one of those domains of heavy-ion nuclear physics that faces the greatest challenges, yet also contains the greatest opportunities. After many summer schools and workshops, in particular over the last decade, the community of nuclear molecular physicists has decided to collaborate in producing a comprehensive collection of lectures and tutorial reviews covering the field. This third volume follows the successful Lect. Notes Phys. 818 (Vol. 1) and 848 (Vol. 2), and comprises six extensive lectures covering the following topics:  - Gamma Rays and Molecular Structure - Faddeev Equation Approach for Three Cluster Nuclear Reactions - Tomography of the Cluster Structure of Light Nuclei Via Relativistic Dissociation - Clustering Effects Within the Dinuclear Model : From Light to Hyper-heavy Molecules in Dynamical Mean-field Approach - Clusterization in Ternary Fission - Clusters in Light N...

  18. Pion production in nuclei

    International Nuclear Information System (INIS)

    Afnan, I.R.; Thomas, A.W.

    1976-01-01

    A method has been suggested for relating μ-capture in nuclei to pion absorption through partially conserved axial vector current hypothesis. The success of the method relies heavily on the knowledge of the pion absorption amplitude at a momentum transfer equal to the μ-meson mass. That is we need to know the pion absorption amplitude off the mass-shell. The simplest nucleus for which this suggestion can be examined is μ-capture in deuterium. The Koltum-Reitan model is used to determine the pion absorption amplitude off the mass shell. In particular the senstivity of this off-mass-shell extrapolution to details of the N-N interaction is studied. (author)

  19. IBA in deformed nuclei

    International Nuclear Information System (INIS)

    Casten, R.F.; Warner, D.D.

    1982-01-01

    The structure and characteristic properties and predictions of the IBA in deformed nuclei are reviewed, and compared with experiment, in particular for 168 Er. Overall, excellent agreement, with a minimum of free parameters (in effect, two, neglecting scale factors on energy differences), was obtained. A particularly surprising, and unavoidable, prediction is that of strong β → γ transitions, a feature characteristically absent in the geometrical model, but manifest empirically. Some discrepancies were also noted, principally for the K=4 excitation, and the detailed magnitudes of some specific B(E2) values. Considerable attention is paid to analyzing the structure of the IBA states and their relation to geometric models. The bandmixing formalism was studied to interpret both the aforementioned discrepancies and the origin of the β → γ transitions. The IBA states, extremely complex in the usual SU(5) basis, are transformed to the SU(3) basis, as is the interaction Hamiltonian. The IBA wave functions appear with much simplified structure in this way as does the structure of the associated B(E2) values. The nature of the symmetry breaking of SU(3) for actual deformed nuclei is seen to be predominantly ΔK=0 mixing. A modified, and more consistent, formalism for the IBA-1 is introduced which is simpler, has fewer free parameters (in effect, one, neglecting scale factors on energy differences), is in at least as good agreement with experiment as the earlier formalism, contains a special case of the 0(6) limit which corresponds to that known empirically, and appears to have a close relationship to the IBA-2. The new formalism facilitates the construction of contour plots of various observables (e.g., energy or B(E2) ratios) as functions of N and chi/sub Q/ which allow the parameter-free discussion of qualitative trajectories or systematics

  20. Spectroscopy of heavy fissionable nuclei

    Indian Academy of Sciences (India)

    2015-08-05

    Aug 5, 2015 ... Nuclei in the actinide chain and beyond are prone to fission owing to ... mass nuclei are typically more difficult, because the intensity is .... j15/2 neutron alignments in a region where shell stablization effects are crucial.

  1. Problem of ''deformed'' superheavy nuclei

    International Nuclear Information System (INIS)

    Sobiczewski, A.; Patyk, Z.; Muntian, I.

    2000-08-01

    Problem of experimental confirmation of deformed shapes of superheavy nuclei situated in the neighbourhood of 270 Hs is discussed. Measurement of the energy E 2+ of the lowest 2+ state in even-even species of these nuclei is considered as a method for this confirmation. The energy is calculated in the cranking approximation for heavy and superheavy nuclei. The branching ratio p 2+ /p 0+ between α decay of a nucleus to this lowest 2+ state and to the ground state 0+ of its daughter is also calculated for these nuclei. The results indicate that a measurement of the energy E 2+ for some superheavy nuclei by electron or α spectroscopy is a promising method for the confirmation of their deformed shapes. (orig.)

  2. Quarks in Few Body Nuclei

    Directory of Open Access Journals (Sweden)

    Holt Roy J.

    2016-01-01

    Full Text Available Electron scattering at very high Bjorken x from hadrons provides an excellent test of models, has an important role in high energy physics, and from nuclei, provides a window into short range correlations. Light nuclei have a key role because of the relatively well-known nuclear structure. The development of a novel tritium target for Jefferson Lab has led to renewed interest in the mass three system. For example, deep inelastic scattering experiments in the light nuclei provide a powerful means to determine the neutron structure function. The isospin dependence of electron scattering from mass-3 nuclei provide information on short range correlations in nuclei. The program using the new tritium target will be presented along with a summary of other experiments aimed at revealing the large-x structure of the nucleon.

  3. Universality of fragment shapes.

    Science.gov (United States)

    Domokos, Gábor; Kun, Ferenc; Sipos, András Árpád; Szabó, Tímea

    2015-03-16

    The shape of fragments generated by the breakup of solids is central to a wide variety of problems ranging from the geomorphic evolution of boulders to the accumulation of space debris orbiting Earth. Although the statistics of the mass of fragments has been found to show a universal scaling behavior, the comprehensive characterization of fragment shapes still remained a fundamental challenge. We performed a thorough experimental study of the problem fragmenting various types of materials by slowly proceeding weathering and by rapid breakup due to explosion and hammering. We demonstrate that the shape of fragments obeys an astonishing universality having the same generic evolution with the fragment size irrespective of materials details and loading conditions. There exists a cutoff size below which fragments have an isotropic shape, however, as the size increases an exponential convergence is obtained to a unique elongated form. We show that a discrete stochastic model of fragmentation reproduces both the size and shape of fragments tuning only a single parameter which strengthens the general validity of the scaling laws. The dependence of the probability of the crack plan orientation on the linear extension of fragments proved to be essential for the shape selection mechanism.

  4. Studies of nuclei using radioactive beams

    International Nuclear Information System (INIS)

    Piercey, R.B.

    1989-07-01

    The 12 month period from May 1988 to July 1989 represents the first full year of our 18 month pilot program in nuclear structure research. In this period, research was initiated to develop a capability for radioactive secondary beams at Argonne National Laboratory using the Atlas and the new Fragment Mass Analyzer (FMA), which is currently under construction. Two major new detector facilities are currently in the final stages of design and testing. The Large-Area, Scintillator Telescope (LAST) detector is fully operational and will be shipped to Argonne National Laboratory in August for fit-tests and in-beam calibrations. The first segments of a new sixteen-segment neutron multiplicity detector have been built and tested. The remaining segments are currently being constructed. Research was continued in the areas of (1) Coulomb excitation studies of rare earth and actinide nuclei; (2) In-beam, gamma-ray spectroscopy of nuclei in the mass 100 region, and (3) Advanced detector design. Several journal articles and abstracts were published or submitted for publication in the reporting period, and others are currently in preparation. Three graduate students participated in the program, one from the University of Florida and two from the Royal Institute of Technology, Stockholm, Sweden

  5. Particles and nuclei, letters

    International Nuclear Information System (INIS)

    2002-01-01

    The present collection of letters from JINR, Dubna, contains eight separate records on the role of the complanar emission of particles in nuclear interaction for E 0 >10 16 eV detected in the stratosphere, 10 B nucleus fragment yields, nuclear teleportation (proposal for an experiment), invisible 'glue' bosons in model field theory, calculation of the ionization differential effective cross sections in fast ion-atom collisions, interactions of ultracold neutrons near surface of solids, g factors as a probe for high-spin structure of neutron-rich Dy isotopes, search for periodicities in experimental data by the autoregressive model methods

  6. Effects of deformations and orientations on neutron-halo structure of light-halo nuclei

    International Nuclear Information System (INIS)

    Sawhney, Gudveen; Gupta, Raj K.; Sharma, Manoj K.

    2013-01-01

    The availability of radioactive nuclear beams have enabled to study the structure of nuclei far from the stability line, which in turn led to the discovery of neutron-halo nuclei. These nuclei, located near the neutron drip-line exhibit a high probability of presence of one or two loosely bound neutrons at a large distance from the rest of nucleons. The fragmentation behavior is studied for 13 cases of 1n-halo nuclei, which include 11 Be, 14 B, 15 C, 17 C, 19 C, 22 N, 22 O, 23 O, 24 O, 24 F, 26 F, 29 Ne and 31 Ne, using the cluster-core model (CCM) extended to include the deformations and orientations of nuclei

  7. K-bar-mesic nuclei

    International Nuclear Information System (INIS)

    Dote, Akinobu; Akaishi, Yoshinori; Yamazaki, Toshimitsu

    2005-01-01

    New nuclei 'K-bar-Mesic Nuclei' having the strangeness are described. At first it is shown that the strongly attractive nature of K-bar N interaction is reasoned inductively from consideration of the relation between Kaonic hydrogen atom and Λ (1405) which is an excited state of hyperon Λ. The K-bar N interactions are reviewed and summarized into three categories: 1. Phenomenological approach with density dependent K-bar N interaction (DD), relativistic mean field (RMF) approach, and hybrid of them (RMF+DD). 2. Boson exchange model. 3. Chiral SU(3) theory. The investigation of some light K-bar-nuclei by Akaishi and Yamazaki using phenomenological K-bar N interaction is explained in detail. Studies by antisymmetrized molecular dynamics (AMD) approach are also presented. From these theoretical researches, the following feature of K-bar-mesic nuclei are revealed: 1) Ground state is discrete and bound by 100 MeV or more. 2) Density is very high in side the K-bar-mesic nuclei. 3) Strange structures develop which are not seen in ordinary nuclei. Finally some recent experiments to explore K-bar-mesic nuclei are reviewed. (S. Funahashi)

  8. Electron scattering for exotic nuclei

    International Nuclear Information System (INIS)

    Suda, T.

    2013-01-01

    An electron scattering facility is under construction in RIKEN RI Beam Factory, Japan, which is dedicated to the structure studies of short-lived nuclei. This is the world's first and currently only facility of its type. The construction is nearly completed, and the first electron scattering experiment off short-lived nuclei will be carried out in the beginning of next year. The charge density distributions of short-lived nuclei will be precisely determined by elastic electron scattering for the first time. Physics pursued at this facility including future perspectives are explained

  9. Cavitation inception from bubble nuclei

    DEFF Research Database (Denmark)

    Mørch, Knud Aage

    2015-01-01

    , and experimental investigations of bubbles and cavitation inception have been presented. These results suggest that cavitation nuclei in equilibrium are gaseous voids in the water, stabilized by a skin which allows diffusion balance between gas inside the void and gas in solution in the surrounding liquid....... The cavitation nuclei may be free gas bubbles in the bulk of water, or interfacial gaseous voids located on the surface of particles in the water, or on bounding walls. The tensile strength of these nuclei depends not only on the water quality but also on the pressure-time history of the water. A recent model...

  10. Gluon density in nuclei

    International Nuclear Information System (INIS)

    Ayala, A.L.

    1996-01-01

    In this talk we present our detailed study (theory and numbers) on the shadowing corrections to the gluon structure functions for nuclei. Starting from rather controversial information on the nucleon structure function which is originated by the recent HERA data, we develop the Glauber approach for the gluon density in a nucleus based on Mueller formula and estimate the value of the shadowing corrections in this case. Then we calculate the first corrections to the Glauber approach and show that these corrections are big. Based on this practical observation we suggest the new evolution equation which takes into account the shadowing corrections and solve it. We hope to convince you that the new evolution equation gives a good theoretical tool to treat the shadowing corrections for the gluons density in a nucleus and, therefore, it is able to provide the theoretically reliable initial conditions for the time evolution of the nucleus-nucleus cascade. The initial conditions should be fixed both theoretically and phenomenologically before to attack such complicated problems as the mixture of hard and soft processes in nucleus-nucleus interactions at high energy or the theoretically reliable approach to hadron or/and parton cascades for high energy nucleus-nucleus interaction. 35 refs., 24 figs., 1 tab

  11. Supersymmetry in nuclei

    CERN Document Server

    Jolie, J

    2002-01-01

    All the elementary particles that make up matter (as do quarks, electrons, neutrinos....) are fermions, the particles that convey the fundamental interactions (as do photons, gluons, W, Z...) are bosons. Composite particles are either bosons, or fermions according to the number of fermions they contain: if this number is even the particle is a boson, otherwise it is a fermion. According to this rule a proton is a fermion and the He sup 4 atom is a boson. Symmetry plays an important role in the standard model, a symmetry is a transformation that connect bosons with other bosons or fermions with other fermions. Supersymmetry associates a boson with a fermion or a fermion with a boson, in fact supersymmetry connects nuclei that are not generally considered as akin. Supersymmetry has just been observed in low energy levels of Gold sup 1 sup 9 sup 5 sup - sup 1 sup 9 sup 6 and Platinum sup 1 sup 9 sup 4 - sup 1 sup 9 sup 5 , it means that the description of these energy levels is simplified and can be made by a co...

  12. Supersymmetry in nuclei

    International Nuclear Information System (INIS)

    Jolie, J.

    2002-01-01

    All the elementary particles that make up matter (as do quarks, electrons, neutrinos....) are fermions, the particles that convey the fundamental interactions (as do photons, gluons, W, Z...) are bosons. Composite particles are either bosons, or fermions according to the number of fermions they contain: if this number is even the particle is a boson, otherwise it is a fermion. According to this rule a proton is a fermion and the He 4 atom is a boson. Symmetry plays an important role in the standard model, a symmetry is a transformation that connect bosons with other bosons or fermions with other fermions. Supersymmetry associates a boson with a fermion or a fermion with a boson, in fact supersymmetry connects nuclei that are not generally considered as akin. Supersymmetry has just been observed in low energy levels of Gold 195-196 and Platinum 194 - 195 , it means that the description of these energy levels is simplified and can be made by a common set of quantum numbers. (A.C.)

  13. Photon interactions with nuclei

    International Nuclear Information System (INIS)

    Thornton, S.T.; Sealock, R.M.

    1989-01-01

    This document is a progress report for DOE Grant No. FG05-89ER40501, A000. The grant began March, 1989. Our primary research effort has been expended at the LEGS project at Brookhaven National Laboratory. This report will summarize our present research effort at LEGS as well as data analysis and publications from previous experiments performed at SLAC. In addition the principal investigators are heavily involved in the CLAS collaboration in Hall B at CEBAF. We have submitted several letters of intent and proposals and have made commitments to construct experimental equipment for CEBAF. We expect our primary experimental effort to continue at LEGS until CEBAF becomes operational. This report will be divided into separate sections describing our progress at LEGS, SLAC, and CEBAF. We will also discuss our significant efforts in the education and training of both undergraduate and graduate students. Photon detectors are described as well as experiments on delta deformation in nuclei of quasielastic scattering and excitation of the delta by 4 He(e,e')

  14. Parity violation in nuclei

    International Nuclear Information System (INIS)

    Robertson, R.G.H.

    1980-01-01

    A summary of parity violating effects in nuclei is given. Thanks to vigorous experimental and theoretical effort, it now appears that a reasonably well-defined value for the weak isovector π-nucleon coupling constant can be obtained. There is one major uncertainty in the analysis, namely the M2/E1 mixing ratio for the 2.79 MeV transition in 21 Ne. This quantity is virtually impossible to calculate reliably and must be measured. If it turns out to be much larger than 1, then a null result in 21 Ne is expected no matter what the weak interaction, so an experimental determination is urgently needed. The most promising approach is perhaps a measurement of the pair internal conversion coefficient. Of course, a direct measurement of a pure isovector case is highly desirable, and it is to be hoped that the four ΔT = 1 experiments will be pushed still further, and that improved calculations will be made for the 6 Li case. Nuclear parity violation seems to be rapidly approaching an interesting and useful synthesis

  15. Symmetries in nuclei

    International Nuclear Information System (INIS)

    Arima, A.

    2003-01-01

    (1) There are symmetries in nature, and the concept of symmetry has been used in art and architecture. The symmetry is evaluated high in the European culture. In China, the symmetry is broken in the paintings but it is valued in the architecture. In Japan, however, the symmetry has been broken everywhere. The serious and interesting question is why these differences happens? (2) In this lecture, I reviewed from the very beginning the importance of the rotational symmetry in quantum mechanics. I am sorry to be too fundamental for specialists of nuclear physics. But for people who do not use these theories, I think that you could understand the mathematical aspects of quantum mechanics and the relation between the angular momentum and the rotational symmetry. (3) To the specialists of nuclear physics, I talked about my idea as follows: dynamical treatment of collective motions in nuclei by IBM, especially the meaning of the degeneracy observed in the rotation bands top of γ vibration and β vibration, and the origin of pseudo-spin symmetry. Namely, if there is a symmetry, a degeneracy occurs. Conversely, if there is a degeneracy, there must be a symmetry. I discussed some details of the observed evidence and this correspondence is my strong belief in physics. (author)

  16. Collective excitations in nuclei

    International Nuclear Information System (INIS)

    Chomaz, Ph.

    1997-01-01

    The properties of the nucleus cannot be reduced to the properties of its constituents: it is a complex system. The fact that many properties of the nucleus are consequences of the existence of mean-field potential is a manifestation of this complexity. In particular the nucleons can thus self-organize in collective motions such as giant resonances. Therefore the study of these collective motions is a very good to understand the properties of the nucleus itself. The purpose of this article was to stress some aspects of these collective vibrations. In particular we have studied how an ensemble of fermions as the nucleus can self-organize in collective vibrations which are behaving like a gas of bosons in weak interaction. The understanding of these phenomena remains one of the important subjects of actually in the context of quantal systems in strong interaction. In particular the study of the states with one or two vibration quanta provides a direct information on the structure if nuclei close to their ground states. (author)

  17. Collective excitations in nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Chomaz, Ph

    1997-12-31

    The properties of the nucleus cannot be reduced to the properties of its constituents: it is a complex system. The fact that many properties of the nucleus are consequences of the existence of mean-field potential is a manifestation of this complexity. In particular the nucleons can thus self-organize in collective motions such as giant resonances. Therefore the study of these collective motions is a very good to understand the properties of the nucleus itself. The purpose of this article was to stress some aspects of these collective vibrations. In particular we have studied how an ensemble of fermions as the nucleus can self-organize in collective vibrations which are behaving like a gas of bosons in weak interaction. The understanding of these phenomena remains one of the important subjects of actually in the context of quantal systems in strong interaction. In particular the study of the states with one or two vibration quanta provides a direct information on the structure if nuclei close to their ground states. (author) 270 refs.

  18. On spallation and fragmentation of heavy ions at intermediate energies

    International Nuclear Information System (INIS)

    Musulmanbekov, G.; Al-Haidary, A.

    2002-01-01

    A new code for simulation of spallation and (multi)fragmentation of nuclei in proton and nucleus induced collisions at intermediate and high energies is developed. The code is a combination of modified intranuclear cascade model with traditional fission - evaporation part and multifragmentation part based on lattice representation of nuclear structure and percolation approach. The production of s-wave resonances and formation time concept included into standard intranuclear cascade code provides correct calculation of excitation energy of residues. This modified cascade code served as a bridge between low and high energy model descriptions of nucleus-nucleus collisions. A good agreement with experiments has been obtained for multiparticle production at intermediate and relatively high energies. Nuclear structure of colliding nuclei is represented as face centered cubic lattice. This representation, being isomorphic to the shell model of nuclear structure, allows to apply percolation approach for nuclear fragmentation. The offered percolation model includes both site and bond percolation. Broken sites represent holes left by nucleons knocked out at cascade state. Therefore, in the first cascade stage mutual rescattering of the colliding nuclei results in knocking some nucleons out of them. After this fast stage paltrily destruct and excited residues remain. On the second stage residual nuclei either evaporate nucleons and light nuclei up to alpha-particles or fragment into pieces with intermediate masses. The choice depends on residue's destruction degree. At low excitation energy and small destruction of the residue the evaporation and fission mechanisms are preferable. The more excitation energy and destruction the more probability of (multi)fragmentation process. Moreover, the more destruction degree of the residual the more the site percolation probability. It is concluded, that at low and intermediate excitation energies the fragmentation of nuclei is slow

  19. Universal odd-even staggering in isotopic fragmentation and spallation cross sections of neutron-rich fragments

    Science.gov (United States)

    Mei, B.; Tu, X. L.; Wang, M.

    2018-04-01

    An evident odd-even staggering (OES) in fragment cross sections has been experimentally observed in many fragmentation and spallation reactions. However, quantitative comparisons of this OES effect in different reaction systems are still scarce for neutron-rich nuclei near the neutron drip line. By employing a third-order difference formula, the magnitudes of this OES in extensive experimental cross sections are systematically investigated for many neutron-rich nuclei with (N -Z ) from 1 to 23 over a broad range of atomic numbers (Z ≈3 -50 ). A comparison of these magnitude values extracted from fragment cross sections measured in different fragmentation and spallation reactions with a large variety of projectile-target combinations over a wide energy range reveals that the OES magnitude is almost independent of the projectile-target combinations and the projectile energy. The weighted average of these OES magnitudes derived from cross sections accurately measured in different reaction systems is adopted as the evaluation value of the OES magnitude. These evaluated OES magnitudes are recommended to be used in fragmentation and spallation models to improve their predictions for fragment cross sections.

  20. Temperatures of exploding nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Serfling, V.; Schwarz, C.; Begemann-Blaich, M.; Fritz, S.; Gross, C.; Kleinevoss, U.; Kunze, W.D; Lynen, U.; Mahi, M.; Mueller, W.F.J.; Odeh, T.; Schnittker, M.; Trautmann, W.; Woerner, A.; Xi, H. [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany); Bassini, R.; Iori, I.; Moroni, A.; Petruzzelli, F. [Milan Univ. (Italy). Ist. di Scienze Fisiche]|[Istituto Nazionale di Fisica Nucleare, Milan (Italy); Gaff, S.J.; Kunde, G.J. [Michigan State Univ., East Lansing, MI (United States). Dept. of Physics and Astronomy]|[Michigan State Univ., East Lansing, MI (United States). National Superconducting Cyclotron Lab.; Imme, G.; Maddalena, V.; Nociforo, C.; Raciti, G.; Riccobene, G.; Romano, F.P.; Saija, A.; Sfienti, C.; Verde, G. [Catania Univ. (Italy). Dipt. di Fisica]|[Istituto Nazionale di Fisica Nucleare, Catania (Italy); Moehlenkamp, T.; Seidel, W. [Forschungszentrum Rossendorf e.V. (FZR), Dresden (Germany); Ocker, B.; Schuettauf, A. [Frankfurt Univ. (Germany). Inst. fuer Kernphysik; Pochodzalla, J. [Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany); Trzcinski, A.; Zwieglinski, B. [Soltan Inst. for Nuclear Studies, Warsaw (Poland)

    1998-01-01

    Breakup temperatures in central collisions of {sup 197}Au+{sup 197}Au at bombarding energies E/A=50 to 200 MeV were determined with two methods. Isotope temperatures, deduced from double ratios of hydrogen, helium, and lithium isotopic yields, increase monotonically with bombarding energy from 5 MeV to 12 MeV, in qualitative agreement with a scenario of chemical freeze-out after adiabatic expansion. Excited-state temperatures, derived from yield ratios of states in {sup 4}He, {sup 5,6}Li, and {sup 8}Be, are about 5 MeV, independent of the projectile energy, and seem to reflect the internal temperature of fragments at their final separation from the system. (orig.)

  1. The mean free path of alpha projectile fragments from 16O-Em at 60 A GeV

    International Nuclear Information System (INIS)

    Zhang Donghai

    1993-01-01

    In EMU 01 emulsion stack exposed to beam of 16 O nuclei with momentum of 60 A GeV/c, 1068 helium fragments from 1460 16 O-Em collisions have been recorded. These fragments were followed until they interacted or left the stack. Among these fragments there are 236 helium fragments interacted with emulsion. Statistical analysis of the mean free path of these fragments were performed. The evidence was found for the anomalously short mean free path in first few centimeters of the point of alpha fragments. (Author)

  2. Influence of the Pauli principle on the one-quasiparticle states in odd spherical nuclei

    International Nuclear Information System (INIS)

    Chan Zuy Khuong

    1980-01-01

    The effect of the Pauli principle on the fragmentation of one-quasiparticle states in odd spherical nuclei is studied within the quasiparticle-phonon nuclear model. It is shown that the Pauli principle influences considerably the position and structure of a few low-lying states. The fragmentation of one-quasiparticle states at intermediate and high excitation energies is slightly affected by the Pauli principle, and the calculations can be performed by taking the Pauli principle into account roughly. (author)

  3. Dynamic polarization of radioactive nuclei

    International Nuclear Information System (INIS)

    Kiselev, Yu.F.; Lyuboshits, V.L.; )

    2001-01-01

    Radioactive nuclei, embedded into a frozen polarized proton target, atr proposed to polarize by means of some dynamic polarization methods. Angular distributions of γ-quanta emitted ny 22 Na(3 + ) in the cascade β-γ-radiation are calculated. It is shown that this distribution does not depend on the spin temperature sing at the Boltzmann distribution of populations among the Zeeman magnetic substates, whereas the tensor polarization of quadrupole nuclei, placed in the electric field of the crystal, causes the considerable sing dependence. The new method promises wide opportunities for the magnetic structure investigations as well as for the study of spin-spin interaction dynamics of rare nuclei in dielectrics. Physical-technical advantages and disadvantages of the given method are discussed for the polarization of heavy nuclei in the on-line implantation mode [ru

  4. The delta in nuclei. Experiments

    International Nuclear Information System (INIS)

    Roy-Stephan, M.

    1989-01-01

    Experimental aspects of the Δ excitation will be presented. The Δ excitation in nuclei will be compared to the free Δ excitation. Various probes will be reviewed and their specific features will be underlined [fr

  5. Electron scattering for exotic nuclei

    Indian Academy of Sciences (India)

    2014-11-04

    Nov 4, 2014 ... Research Center for Electron-Photon Science, Tohoku University, 1-2-1 ... nuclei precisely determined by elastic scattering [1]. .... In order to fulfill these requirements, a window-frame shaped dipole magnet with a gap.

  6. Collisions between complex atomic nuclei

    International Nuclear Information System (INIS)

    Vaagen, J. S.

    1977-08-01

    The use of heavy ion accelerators in the study of nuclear structure and states is reviewed. The reactions discussed are the quasielastic reactions in which small amounts of energy and few particles are exchanged between the colliding nuclei. The development of heavy ion accelerators is also discussed, as well as detection equipment. Exotic phenomena, principally the possible existence of superheavy nuclei, are also treated. (JIW)

  7. Particles and nuclei in PANIC

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    1987-07-15

    PANIC is the triennal International Conference on Particles and Nuclei, and judging from the latest PANIC, held in Kyoto from 20-24 April there is no need for panic yet. Faced with two pictures – one of nuclei described in nucleon and meson terms, and another of nucleons containing quarks and gluons – physicists are intrigued to know what new insights from the quark level can tell us about nuclear physics, or vice versa.

  8. Particles and nuclei in PANIC

    International Nuclear Information System (INIS)

    Anon.

    1987-01-01

    PANIC is the triennal International Conference on Particles and Nuclei, and judging from the latest PANIC, held in Kyoto from 20-24 April there is no need for panic yet. Faced with two pictures – one of nuclei described in nucleon and meson terms, and another of nucleons containing quarks and gluons – physicists are intrigued to know what new insights from the quark level can tell us about nuclear physics, or vice versa

  9. Investigation of copper nuclei

    International Nuclear Information System (INIS)

    Delfini, M.G.

    1983-01-01

    An extensive study has been performed on copper isotopes in the mass region A=63-66. The results of a precise measurement are presented on the properties of levels of 64 Cu and 66 Cu. They were obtained by bombarding the 63 Cu and 65 Cu nuclei with neutrons. The gamma spectra collected after capture of thermal, 2-keV, 24-keV neutrons have been analysed and combined to give a rather extensive set of precise level energies and gamma transition strengths. From the angular distribution of the gamma rays it is possible to obtain information concerning the angular momentum J of several low-lying states. The level schemes derived from such measurements have been used as a test for calculations in the framework of the shell model. The spectral distributions of eigenstates in 64 Cu for different configuration spaces are presented and discussed. In this study the relative importance of configurations with n holes in the 1f7/2 shell with n up to 16, are investigated. It is found that the results strongly depend on the values of the single-particle energies. The results of the spectral-distribution method were utilized for shell-model calculations. From the information obtained from the spectral analysis it was decided to adopt a configuration space which includes up to one hole in the 1f7/2 shell and up to two particles in the 1g9/2 shell. Further, restrictions on seniority and on the coupling of the two particles in the 1g9/2 orbit have been applied and their effects have been studied. It is found that the calculated excitation energies reproduce the measured values in a satisfactory way, but that some of the electromagnetic properties are less well in agreement with experimental data. (Auth.)

  10. Reactions with fast radioactive beams of neutron-rich nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Aumann, T. [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany)

    2005-11-01

    The neutron dripline has presently been reached only for the lightest nuclei up to the element oxygen. In this region of light neutron-rich nuclei, scattering experiments are feasible even for dripline nuclei by utilizing high-energy secondary beams produced by fragmentation. In the present article, reactions of high-energy radioactive beams will be exemplified using recent experimental results mainly derived from measurements of breakup reactions performed at the LAND and FRS facilities at GSI and at the S800 spectrometer at the NSCL. Nuclear and electromagnetically induced reactions allow probing different aspects of nuclear structure at the limits of stability related to the neutron-proton asymmetry and the weak binding close to the dripline. Properties of the valence-neutron wave functions are studied in the one-neutron knockout reaction, revealing the changes of shell structure when going from the beta-stability line to more asymmetric loosely bound neutron-rich systems. The vanishing of the N=8 shell gap for neutron-rich systems like {sup 11}Li and {sup 12}Be, or the new closed N=14, 16 shells for the oxygen isotopes are examples. The continuum of weakly bound nuclei and halo states can be studied by inelastic scattering. The dipole response, for instance, is found to change dramatically when going away from the valley of stability. A redistribution of the dipole strength towards lower excitation energies is observed for neutron-rich nuclei, which partly might be due to a new collective excitation mode related to the neutron-proton asymmetry. Halo nuclei in particular show strong dipole transitions to the continuum at the threshold, being directly related to the ground-state properties of the projectile. Finally, an outlook on future experimental prospects is given. (orig.)

  11. Reactions with fast radioactive beams of neutron-rich nuclei

    International Nuclear Information System (INIS)

    Aumann, T.

    2005-11-01

    The neutron dripline has presently been reached only for the lightest nuclei up to the element oxygen. In this region of light neutron-rich nuclei, scattering experiments are feasible even for dripline nuclei by utilizing high-energy secondary beams produced by fragmentation. In the present article, reactions of high-energy radioactive beams will be exemplified using recent experimental results mainly derived from measurements of breakup reactions performed at the LAND and FRS facilities at GSI and at the S800 spectrometer at the NSCL. Nuclear and electromagnetically induced reactions allow probing different aspects of nuclear structure at the limits of stability related to the neutron-proton asymmetry and the weak binding close to the dripline. Properties of the valence-neutron wave functions are studied in the one-neutron knockout reaction, revealing the changes of shell structure when going from the beta-stability line to more asymmetric loosely bound neutron-rich systems. The vanishing of the N=8 shell gap for neutron-rich systems like 11 Li and 12 Be, or the new closed N=14, 16 shells for the oxygen isotopes are examples. The continuum of weakly bound nuclei and halo states can be studied by inelastic scattering. The dipole response, for instance, is found to change dramatically when going away from the valley of stability. A redistribution of the dipole strength towards lower excitation energies is observed for neutron-rich nuclei, which partly might be due to a new collective excitation mode related to the neutron-proton asymmetry. Halo nuclei in particular show strong dipole transitions to the continuum at the threshold, being directly related to the ground-state properties of the projectile. Finally, an outlook on future experimental prospects is given. (orig.)

  12. Spectrin-like proteins in plant nuclei

    NARCIS (Netherlands)

    Ruijter, de N.C.A.; Ketelaar, T.; Blumenthal, S.S.D.; Emons, A.M.C.; Schel, J.H.N.

    2000-01-01

    We analysed the presence and localization of spectrin-like proteins in nuclei of various plant tissues, using several anti-erythrocyte spectrin antibodies on isolated pea nuclei and nuclei in cells. Western blots of extracted purified pea nuclei show a cross-reactive pair of bands at 220–240 kDa,

  13. Solar 'hot spots' are still hot

    Science.gov (United States)

    Bai, Taeil

    1990-01-01

    Longitude distributions of solar flares are not random but show evidence for active zones (or hot spots) where flares are concentrated. According to a previous study, two hot spots in the northern hemisphere, which rotate with a synodic period of about 26.72 days, produced the majority of major flares, during solar cycles 20 and 21. The more prominent of these two hot spots is found to be still active during the rising part of cycle 22, producing the majority of northern hemisphere major flares. The synodic rotation period of this hot spot is 26.727 + or - 0.007 days. There is also evidence for hot spots in the southern hemisphere. Two hot spots separated by 180 deg are found to rotate with a period of 29.407 days, with one of them having persisted in the same locations during cycles 19-22 and the other, during cycles 20-22.

  14. Solar hot spots are still hot

    International Nuclear Information System (INIS)

    Bai, T.

    1990-01-01

    Longitude distributions of solar flares are not random but show evidence for active zones (or hot spots) where flares are concentrated. According to a previous study, two hot spots in the northern hemisphere, which rotate with a synodic period of about 26.72 days, produced the majority of major flares, during solar cycles 20 and 21. The more prominent of these two hot spots is found to be still active during the rising part of cycle 22, producing the majority of northern hemisphere major flares. The synodic rotation period of this hot spot is 26.727 + or - 0.007 days. There is also evidence for hot spots in the southern hemisphere. Two hot spots separated by 180 deg are found to rotate with a period of 29.407 days, with one of them having persisted in the same locations during cycles 19-22 and the other, during cycles 20-22. 14 refs

  15. Studies of complex fragment emission in heavy ion reactions

    International Nuclear Information System (INIS)

    Sobotka, L.G.

    1989-01-01

    The production of large fragments, fragments with mass between light particles and fission fragments, in intermediate and high energy nuclear reactions has fostered the proposal of a number of novel reaction mechanisms. These include liquid-vapor equilibrium and nuclear shattering. Temporarily left in the wake of these exciting proposed mechanisms was the old standard, statistical decay of compound nuclei. To be sure, the standard treatment of compound nucleus decay did not deal with large fragment production. However, this omission was not due to any fundamental deficiency of statistical models, but rather an uncertainty concerning exactly how to splice large fragment emission into statistical models. A large portion of our program deals with this problem. Specifically, by studying the yields of large fragments produced in sufficiently low energy reactions we are attempting to deduce the asymmetry and l-wave dependence of large fragment emission from compound nuclear intermediates. This, however, is only half of the problem. Since the novel mechanisms proposed for large fragment emission were spawned by intermediate and high energy reaction data, we must also realize the relevance of the compound nucleus mechanisms at high energies. It is not unreasonable to suspect that compound nucleus-like objects are formed with less than complete momentum transfer and perhaps less than complete mass transfer. Therefore the study of energy, mass, and angular momentum transfer in incomplete fusion and non-compound reactions. This thread joins the apparently divergent subjects covered in this report

  16. String fragmentation; La fragmentation des cordes

    Energy Technology Data Exchange (ETDEWEB)

    Drescher, H.J.; Werner, K. [Laboratoire de Physique Subatomique et des Technologies Associees - SUBATECH, Centre National de la Recherche Scientifique, 44 - Nantes (France)

    1997-10-01

    The classical string model is used in VENUS as a fragmentation model. For the soft domain simple 2-parton strings were sufficient, whereas for higher energies up to LHC, the perturbative regime of the QCD gives additional soft gluons, which are mapped on the string as so called kinks, energy singularities between the leading partons. The kinky string model is chosen to handle fragmentation of these strings by application of the Lorentz invariant area law. The `kinky strings` model, corresponding to the perturbative gluons coming from pQCD, takes into consideration this effect by treating the partons and gluons on the same footing. The decay law is always the Artru-Menessier area law which is the most realistic since it is invariant to the Lorentz and gauge transformations. For low mass strings a manipulation of the rupture point is necessary if the string corresponds already to an elementary particle determined by the mass and the flavor content. By means of the fragmentation model it will be possible to simulate the data from future experiments at LHC and RHIC 3 refs.

  17. Dimensional crossover in fragmentation

    Science.gov (United States)

    Sotolongo-Costa, Oscar; Rodriguez, Arezky H.; Rodgers, G. J.

    2000-11-01

    Experiments in which thick clay plates and glass rods are fractured have revealed different behavior of fragment mass distribution function in the small and large fragment regions. In this paper we explain this behavior using non-extensive Tsallis statistics and show how the crossover between the two regions is caused by the change in the fragments’ dimensionality during the fracture process. We obtain a physical criterion for the position of this crossover and an expression for the change in the power-law exponent between the small and large fragment regions. These predictions are in good agreement with the experiments on thick clay plates.

  18. Beta decay and magnetic moments as tools to probe nuclear structure. Study of neutron-rich nuclei around N=40; Decroissance beta et moments magnetiques comme outils pour sonder la structure nucleaire. Etude des noyaux riches en neutrons autour de N=40

    Energy Technology Data Exchange (ETDEWEB)

    Matea, I

    2003-12-01

    The evolution of nuclear structure in nuclei far from the {beta} stability line is one of the 'hot topics' in modern experimental and theoretical nuclear physics. The present thesis is devoted to the study of structure of neutron-rich nuclei around N=40. The evolution of the neutron g9/2 orbital with increasing number of neutrons is one of the key points defining the structure of these nuclei at low excitation energy. We used for this investigation as experimental tools the magnetic dipole moments measurements and the {beta} decay spectroscopy. For the measurement of the gyromagnetic factor of the 9/2{sup +} isomeric state in Fe{sup 61} we have applied the TDPAD method. This method (like most of measurements of nuclear moments) requires an oriented ensemble of nuclei. The orientation of Fe{sup 61m} was achieved via the fragmentation of Ni{sup 64} at 55 MeV/u and the selection of the fragment momentum with the LISE spectrometer at GANIL. The experimental device was specially conceived to preserve the alignment up to the implantation point. The measured value of the g factor was compared with large-scale shell model and Hartree-Fock-Bogoliubov model predictions. The nuclei studied via {beta} decay were produced by the fragmentation of Kr{sup 86} at 58 MeV/u. For the selection of reaction products we used for the first time the LISE2000 spectrometer and for the detection of {gamma} rays four EXOGAM clover detectors. We measured 5 new lifetimes and 4 lifetimes with a higher precision. From the prompt {beta}{gamma} coincidences we identified new states in the daughter nuclei, as it is the case of the first 2{sup +} excited states in Fe{sup 68} and Ni{sup 72}. The results were compared with the predictions of the large-scale shell model. Other transitions were observed for the first time in {beta}{gamma} decay of Ti{sup 60}, Fe{sup 70} and Co{sup 71,73}. (author)

  19. The energy overcompensating disintegrations of residual target nuclei damaged in hadron-nucleus collisions

    International Nuclear Information System (INIS)

    Strugalski, Z.

    1995-01-01

    Massive target nuclei damaged in hadron-nucleus collisions at high energies are used to disintegrate into nuclear fragments. In many cases such breakup is egzoergic - some portion of nuclear energy is released; this portion should be overcompensating the energy used for the nuclear damage, in some cases. 30 refs

  20. Fragmentation of single-particle states and neutron strength functions

    International Nuclear Information System (INIS)

    Soloviev, V.G.

    1975-01-01

    Fragmentation of one-particle states in odd deformed nuclei is studied in the framework of a model based on the interaction between quasiparticles and phonons. A principally new semi-microscopic method for calculation of force functions using the data on fragmentation of one-particle states is suggested. Calculated s- and p-wave neutron force functions in 239 U and 169 Er are in good agreement with experiment. The correct description of the s-wave neutron force function in the vicinity of is obtained in particular for Sn isotopes/ of its minimum is obtained in particular for Sn isotopes

  1. SAPhIR: a fission-fragment detector

    International Nuclear Information System (INIS)

    Theisen, Ch.; Gautherin, C.; Houry, M.; Korten, W.; Le Coz, Y.; Lucas, R.; Barreau, G.; Doan, T. P.; Belier, G.; Meot, V.; Ethvignot, Th.; Cahan, B.; Le Coguie, A.; Coppolani, X.; Delaitre, B.; Le Bourlout, P.; Legou, Ph.; Maillard, O.; Durand, G.; Bouillac, A.

    1998-01-01

    SAPhIR is the acronym for S a clay A q uitaine P ho tovoltaic cells for I s omer R e search. It consists of solar cells, used for fission-fragment detection. It is a collaboration between 3 laboratories: CEA Saclay, CENBG Bordeaux and CEA Bruyeres le Chatel. The coupling of a highly efficient fission-fragment detector like SAPhIR with EUROBALL will provide new insights in the study of very deformed nuclear matter and in the spectroscopy of neutron-rich nuclei

  2. On the nuclear fragmentation mechanisms in nuclear collisions at intermediate and high energies

    International Nuclear Information System (INIS)

    Jipa, Al; Besliu, C.; Felea, D.

    2004-01-01

    The nuclear fragmentation mechanisms can be discussed by taking into account different scales related to the fragment sizes. Considering two fragmentation mechanisms of the nuclei at the same incident energy an analysis of the experimental results obtained was done. Goldhaber formula was improved by analyzing the discrepancies between data and theories concerning the projectile fragmentation. We implied that the projectile fragmentation process would be governed by the distribution of nucleon momenta in the projectile after the collision occurred. We used in our analysis protons from the 4 He + 7 Li at 4.5 GeV/c per nucleon incident momentum, as well as from 40 Ar + 12 C at 213 AMeV bombarding energy. We proved that in order to proceed in analyzing the projectile fragmentation process at intermediate and high energies one has to consider the dependence σ 0 on the apparent temperature of projectile nucleus after the collision took place. The generalized Bertsch correction for light projectile nuclei and fragments was used and the number of spatial correlations between identical nucleons having anticorrelated momenta was found. Thus we found apparent temperature values close to the separation energies of the considered fragments per number of fragments. The temperatures associated to kinetic energy spectra of the projectile fragments were calculated following two methods. The results from Bauer's method were compared with those obtained by fitting the kinetic energy distributions of the projectile fragments in the rest frame of the projectile with a Maxwellian curve. We also accomplished the comparison of the experimental results with similar events simulated with RQMD 2.4. All the results obtained suggested two nuclear fragmentation mechanisms: a sudden fragmentation by explosive mechanisms, like shock waves and a slow fragmentation by the 'fission' of the spectator regions, mainly because of the interactions with the particles or fragments emitted from the

  3. Shell closure at the touching point of nuclear fragments

    International Nuclear Information System (INIS)

    Poenaru, D.N.; Greiner, W.; Gherghescu, R.A.

    1998-01-01

    Shell correction energy of the fission fragments remains practically unchanged when the separation distance increases from the sum of their radii up to infinity. The variation with mass asymmetry of the total deformation energy at the touching point configuration shows the valleys corresponding to different decay modes, which are produced when the two proton and/or the two neutron numbers are magic or almost magic. We present a contour plot of the deformation energy of the proton-rich α-emitter 106 Te, showing for the first time the α-decay valley. Different valleys mainly due to the doubly magic nuclei 100,132 Sn, 208 Pb, and other magic numbers, are illustrated by plotting the deformation energy at the touching point versus the proton number of the fragment, for the following parent nuclei: 106 Te; 116 Ce; 212 Po; 228 Th; 258 Fm, and 264 Fm. (author). Letter-to-the-editor

  4. Collective two-phonon states in deformed nuclei

    International Nuclear Information System (INIS)

    Solov'ev, V.G.; Shirikova, N.Y.

    1982-01-01

    The Pauli principle in the two-phonon components of the wave functions is taken into account within the framework of the quasiparticle-phonon model of the nucleus with phonon operators depending on the sign of the projection of the angular momentum. The centroid energies of collective two-phonon states in even-even deformed nuclei are calculated and it is shown that the inclusion of the Pauli principle shifts them by 1--3 MeV to higher energies. The shifts of the three-phonon poles due to the inclusion of the Pauli principle in the three-phonon components of the wave functions are calculated. Strong fragmentation of collective two-phonon states whose energy centroids are 3--5 MeV should be expected. It is concluded that collective two-phonon states need not exist in deformed nuclei. The situation with the 168 Er nucleus and the Th and U isotopes is analyzed

  5. Situation with collective two-phonon states in deformed nuclei

    International Nuclear Information System (INIS)

    Soloviev, V.G.; Shirikova, N.Yu.

    1982-01-01

    Within the quasiparticle-phonon nuclear model with the operators of phonons depending on the sign of the angular momentum projection, the Pauli principle is taken into account in the two-phonon components of the wave functions. The centroid energies of the collective two-phonon states in even-even deformed nuclei are calculated. It is shown that the inclusion of the Pauli principle leads to their shift by 1-3 MeV towards high energies. The shifts of three-phonon poles due to the Pauli principle are calculated in the three-phonon components of the wave functions. The collective two-phonon states, the centroid energies of which are 3-5 MeV, are expected to be strongly fragmented. The conclusion is confirmed that the collective two-phonon states should not exist in deformed nuclei. The situation in 168 Er and in the 228 Th isotopes is analysed

  6. From heavy nuclei to super-heavy nuclei

    International Nuclear Information System (INIS)

    Theisen, Ch.

    2003-01-01

    The existence of super-heavy nuclei has been predicted nearly fifty years ago. Due to the strong coulomb repulsion, the stabilisation of these nuclei is possible only through shell effects. The reasons for this fragile stability, as well as the theoretical predictions concerning the position of the island of stability are presented in the first part of this lecture. In the second part, experiments and experimental techniques which have been used to synthesize or search for super-heavy elements are described. Spectroscopic studies performed in very heavy elements are presented in the following section. We close this lecture with techniques that are currently being developed in order to reach the superheavy island and to study the structure of very-heavy nuclei. (author)

  7. Complete destruction of heavy nuclei by hadrons and nuclei

    International Nuclear Information System (INIS)

    Tolstov, K.D.

    1980-01-01

    The total disintegration is considered of Ag and Pb nuclei and 4 He, 12 C nuclei With a momentum of 4.5 GeV/c per nucleon. It is shown that nucleons are mainly emitted, and there is no residual nUcleus the mass of which is comparable to that of the primary nucleus. The probability of total nucleus disintegration is considered as a function of projectile energy and the mass. The multiplicity, energy and emission angle of particles are considerred as well. It is shown that the density of nuclear matter in the overlap zone of colliding nuclei exceeds the usual one by a factor of approximately 4. A comparison is made with interaction models. A conclusion is drawn of the collective interaction mechanism (perhaps, of the shock wave type) of particle ejection from the target nucleus at the first stage of interaction and of explosive decay of the residual nucleus at the next one

  8. Embedded Fragments Registry (EFR)

    Data.gov (United States)

    Department of Veterans Affairs — In 2009, the Department of Defense estimated that approximately 40,000 service members who served in OEF/OIF may have embedded fragment wounds as the result of small...

  9. Fragmentation Main Model

    Data.gov (United States)

    Earth Data Analysis Center, University of New Mexico — The fragmentation model combines patch size and patch continuity with diversity of vegetation types per patch and rarity of vegetation types per patch. A patch was...

  10. Stone fragmentation by ultrasound

    Indian Academy of Sciences (India)

    Unknown

    In the present work, enhancement of the kidney stone fragmentation by using ultrasound is studied. The cavi- ... ment system like radiation pressure balance, the power is given by ... Thus the bubble size has direct relationship with its life and.

  11. Fragment capture device

    Science.gov (United States)

    Payne, Lloyd R.; Cole, David L.

    2010-03-30

    A fragment capture device for use in explosive containment. The device comprises an assembly of at least two rows of bars positioned to eliminate line-of-sight trajectories between the generation point of fragments and a surrounding containment vessel or asset. The device comprises an array of at least two rows of bars, wherein each row is staggered with respect to the adjacent row, and wherein a lateral dimension of each bar and a relative position of each bar in combination provides blockage of a straight-line passage of a solid fragment through the adjacent rows of bars, wherein a generation point of the solid fragment is located within a cavity at least partially enclosed by the array of bars.

  12. DNA fragmentation in spermatozoa

    DEFF Research Database (Denmark)

    Rex, A S; Aagaard, J.; Fedder, J

    2017-01-01

    Sperm DNA Fragmentation has been extensively studied for more than a decade. In the 1940s the uniqueness of the spermatozoa protein complex which stabilizes the DNA was discovered. In the fifties and sixties, the association between unstable chromatin structure and subfertility was investigated....... In the seventies, the impact of induced DNA damage was investigated. In the 1980s the concept of sperm DNA fragmentation as related to infertility was introduced as well as the first DNA fragmentation test: the Sperm Chromatin Structure Assay (SCSA). The terminal deoxynucleotidyl transferase nick end labelling...... (TUNEL) test followed by others was introduced in the nineties. The association between DNA fragmentation in spermatozoa and pregnancy loss has been extensively investigated spurring the need for a therapeutic tool for these patients. This gave rise to an increased interest in the aetiology of DNA damage...

  13. Fragment Impact Toolkit (FIT)

    Energy Technology Data Exchange (ETDEWEB)

    Shevitz, Daniel Wolf [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Key, Brian P. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Garcia, Daniel B. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-09-05

    The Fragment Impact Toolkit (FIT) is a software package used for probabilistic consequence evaluation of fragmenting sources. The typical use case for FIT is to simulate an exploding shell and evaluate the consequence on nearby objects. FIT is written in the programming language Python and is designed as a collection of interacting software modules. Each module has a function that interacts with the other modules to produce desired results.

  14. Reflection asymmetric shapes in nuclei

    International Nuclear Information System (INIS)

    Ahmad, I.; Carpenter, M.P.; Emling, H.

    1989-01-01

    Experimental data show that there is no even-even nucleus with a reflection asymmetric shape in its ground state. Maximum octupole- octupole correlations occur in nuclei in the mass 224 (N∼134, Z∼88) region. Parity doublets, which are the characteristic signature of octupole deformation, have been observed in several odd mass Ra, Ac and Pa nuclei. Intertwined negative and positive parity levels have been observed in several even-even Ra and Th nuclei above spin ∼8ℎ. In both cases, the opposite parity states are connected by fast El transitions. In some medium-mass nuclei intertwined negative and positive parity levels have also been observed above spin ∼7ℎ. The nuclei which exhibit octupole deformation in this mass region are 144 Ba, 146 Ba and 146 Ce; 142 Ba, 148 Ce, 150 Ce and 142 Xe do not show these characteristics. No case of parity doublet has been observed in the mass 144 region. 32 refs., 16 figs., 1 tab

  15. Experimental determination of fragment excitation energies in multifragmentation events

    International Nuclear Information System (INIS)

    Marie, N.; Natowitz, J.B.; Assenard, M.; Bacri, Ch.O.

    1998-01-01

    For 50 MeV/nucleon 129 Xe + nat Sn multifragmentation events, by means of correlation techniques, the multiplicities of the hydrogen and helium isotopes which were emitted by the hot primary excited fragments produced at the stage of the disassembly of an equilibrated hot source are determined. The relative kinetic energy distributions between the primary clusters and the light charged particles that they evaporate are also derived. From the comparison between the secondary multiplicities observed experimentally and the multiplicities predicted by the GEMINI model, it is concluded that the source breaks into primary fragments which are characterized by the same N/Z ratio as the combined system. Knowing the secondary light charged particle multiplicities and kinetic energies, the average charges of the hot fragments and are reconstructed their mean excitation energies are estimated. The fragment excitation energies are equal to 3.0 MeV/nucleon for the full range of intermediate mass fragment atomic number. This global constancy indicates that, on the average, thermodynamical equilibrium was achieved at the disassembly stage of the source. (author)

  16. Experimental determination of fragment excitation energies in multifragmentation events

    Energy Technology Data Exchange (ETDEWEB)

    Marie, N.; Natowitz, J.B. [Texas A and M Univ., College Station, TX (United States). Cyclotron Inst.; Chbihi, A.; Le Fevre, A.; Salou, S.; Wieleczko, J.P.; Gingras, L.; Auger, G. [Grand Accelerateur National d`Ions Lourds, 14 - Caen (France); Assenard, M. [Nantes Univ., 44 (France); Bacri, Ch.O. [Centre National de la Recherche Scientifique, CNRS, 91 - Orsay (France)] [and others

    1998-03-17

    For 50 MeV/nucleon {sup 129}Xe + {sup nat}Sn multifragmentation events, by means of correlation techniques, the multiplicities of the hydrogen and helium isotopes which were emitted by the hot primary excited fragments produced at the stage of the disassembly of an equilibrated hot source are determined. The relative kinetic energy distributions between the primary clusters and the light charged particles that they evaporate are also derived. From the comparison between the secondary multiplicities observed experimentally and the multiplicities predicted by the GEMINI model, it is concluded that the source breaks into primary fragments which are characterized by the same N/Z ratio as the combined system. Knowing the secondary light charged particle multiplicities and kinetic energies, the average charges of the hot fragments and are reconstructed their mean excitation energies are estimated. The fragment excitation energies are equal to 3.0 MeV/nucleon for the full range of intermediate mass fragment atomic number. This global constancy indicates that, on the average, thermodynamical equilibrium was achieved at the disassembly stage of the source. (author) 25 refs.

  17. Estimates of production and structure of nuclei with Z = 119

    Science.gov (United States)

    Adamian, G. G.; Antonenko, N. V.; Lenske, H.

    2018-02-01

    The comparative analysis of the hot fusion reactions 50Ti +247-249Bk and 51V +246-248Cm for synthesis of element 119 is made with the dinuclear system model and the prediction of nuclear properties of the microscopic-macroscopic approach, where the closed proton shell at Z ≥ 120 is expected. The quasiparticle structures of nuclei in the α-decay chain of 295119 and a possible spread of alpha energies are studied. The calculated values of Qα are compared with available experimental data. The termination of the α-decay chain of 295119 is revealed.

  18. Protonic decay of oriented nuclei

    International Nuclear Information System (INIS)

    Kadmensky, S.G.

    2002-01-01

    On the basis of the multiparticle theory of protonic decay, the angular distributions of protons emitted by oriented spherical and deformed nuclei in the laboratory frame and in the internal coordinate frame of deformed parent nuclei are constructed with allowance for symmetry with respect to time inversion. It is shown that, because of the deep-subbarrier character of protonic decay, the adiabatic approximation is not applicable to describing the angular distributions of protons emitted by oriented deformed nuclei and that the angular distribution of protons in the laboratory frame does not coincide with that in the internal coordinate frame. It is demonstrated that these angular distributions coincide only if the adiabatic and the semiclassical approximation are simultaneously valid

  19. Nuclei in a neutron star

    International Nuclear Information System (INIS)

    Oyamatsu, K.; Yamada, M.

    1994-01-01

    We report on the recent progress in understanding the matter in the crust of a neutron star. For nuclides in the outer crust, recently measured masses of neutron-rich nuclei enable us to determine more accurately the stable nuclide as a function of the matter density. In the inner crust, the compressible liquid-drop model predicts successive change of the nuclear shape, from sphere to cylinder, slab, cylindrical hole and spherical hole at densities just before the transition to uniform matter. In order to go beyond the liquiddrop model, we performed the Thomas-Fermi calculation paying special attention to the surface diffuseness, and have recently calculated the shell energies of the non-spherical nuclei. We have found from these studies that all these non-spherical nuclei exist stably in the above order even if we include the surface diffuseness and shell energies. (author)

  20. Some aspects of the use of deep inelastic transfer reactions to produce nuclei far from stability and nuclei with large angular momenta

    International Nuclear Information System (INIS)

    Volkov, V.V.

    1980-01-01

    Some experimental data are considered that indicate the validity of the Q/sub gg/ systematics of cross sections for production of isotopes in multinucleon transfer reactions for any target-projectile combination. The effect of the nuclear structure of the light fragment on the evolution and disintegration of the double nuclear system formed in deep inelastic collisions of complex nuclei is discussed. Predominance of the α-particle emission over all other channels of the disintegration of the double nuclear system is demonstrated. It is shown that deep inelastic transfer reactions can be used to study the deformation of nuclei with large angular momenta. 9 figures

  1. Form coexistence in light krypton nuclei. Isomeric spectroscopy of 72,74Kr nuclei and Coulomb excitation of the 76Kr radioactive beam

    International Nuclear Information System (INIS)

    Bouchez, Emmanuelle

    2003-01-01

    The first part of this research thesis proposes an overview of the different theoretical calculations elaborated in the region of light krypton nuclei, and of published experimental results. The second part reports the electron and gamma isomeric spectroscopy of 72,74 Kr nuclei after fragmentation of the projectile by a magnetic separator (experimental installation, experimental results, discussion). The third part reports the study of the Coulomb excitation of the 76 Kr radioactive beam (method and experimental installation, data analysis and results in terms of germanium and silicon spectra, and form of the 76 Kr)

  2. Dynamics of fragments and associated phenomena in heavy-ion collisions using a modified secondary algorithm

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Rohit [Department of Physics, Panjab University, Chandigarh-160014 (India)

    2016-05-06

    We discuss the stability of fragments identified by secondary algorithms used to construct fragments within quantum molecular dynamics model. For this purpose we employ three different algorithms for fragment identification. 1) The conventional minimum spanning tree (MST) method based on the spatial correlations, 2) an improved version of MST with additional binding energy constraints of cold nuclear matter, 3) and that of hot matter. We find significant role of thermal binding energies over cold matter binding energies. Significant role is observed for fragment multiplicities and stopping of fragments. Whereas insignificant effect is observed on fragment’s flow.

  3. Hot tub folliculitis

    Science.gov (United States)

    ... survives in hot tubs, especially tubs made of wood. Symptoms The first symptom of hot tub folliculitis ... may help prevent the problem. Images Hair follicle anatomy References D'Agata E. Pseudomonas aeruginosa and other ...

  4. Neutron scattering on deformed nuclei

    International Nuclear Information System (INIS)

    Hansen, L.F.; Haight, R.C.; Pohl, B.A.; Wong, C.; Lagrange, C.

    1984-09-01

    Measurements of neutron elastic and inelastic differential cross sections around 14 MeV for 9 Be, C, 181 Ta, 232 Th, 238 U and 239 Pu have been analyzed using a coupled channel (CC) formalism for deformed nuclei and phenomenological global optical model potentials (OMP). For the actinide targets these results are compared with the predictions of a semi-microscopic calculation using Jeukenne, Lejeune and Mahaux (JLM) microscopic OMP and a deformed ground state nuclear density. The overall agreement between calculations and the measurements is reasonable good even for the very light nuclei, where the quality of the fits is better than those obtained with spherical OMP

  5. Nuclei, hadrons, and elementary particles

    International Nuclear Information System (INIS)

    Bopp, F.W.

    1989-01-01

    This book is a short introduction to the physics of the nuclei, hadrons, and elementary particles for students of physics. Important facts and model imaginations on the structure, the decay, and the scattering of nuclei, the 'zoology' of the hadrons and basic facts of hadronic scattering processes, a short introduction to quantum electrodynamics and quantum chromodynamics and the most important processes of lepton and parton physics, as well as the current-current approach of weak interactions and the Glashow-Weinberg-Salam theory are presented. (orig.) With 153 figs., 10 tabs [de

  6. Octupole shapes in heavy nuclei

    International Nuclear Information System (INIS)

    Ahmad, I.

    1994-01-01

    Theoretical calculations and measurements show the presence of strong octupole correlations in thecyround states and low-lying states of odd-mass and odd-odd nuclei in the RaPa region. Evidence for octupole correlations is provided by the observation of parity doublets and reductions in M1 matrix elements, decoupling parameters, and Coriolis matrix elements Involving high-j states. Enhancement of E1 transition rates has also been observed for some of the octupole deformed nuclei. The most convincing argument for octupole deformation is provided by the similarities of the reduced alpha decay rates to the two members of parity doublets

  7. Exotic Nuclei Arena in JHP

    International Nuclear Information System (INIS)

    Nomura, T.

    1991-12-01

    The Exotic Nuclei Arena planned in Japanese Hadron Project aims to accelerate various unstable nuclei produced in 1-GeV proton-induced reactions up to 6.5 MeV/u by means of heavy-ion linacs. The present status of research and development for the Earena is briefly reported. The construction of the prototype facility to accelerate unstable beams up to 0.8 MeV/u is planned in 1992-94, in which the existing cyclotron in INS is used as the primary accelerator. (author)

  8. Are there superheavy atomic nuclei

    International Nuclear Information System (INIS)

    Herrmann, G.

    1982-04-01

    The author presents a populary introduction to the formation of nuclei with special regards to superheavy nuclei. After a general description of the methods of physics the atomic hypothesis is considered. Thereafter the structure of the nucleus is discussed, and the different isotopes are considered. Then radioactivity is described as an element transmutation. Thereafter the thermonuclear reactions in the sun are considered. Then the synthesis of elements using heavy ion reactions is described. In this connection the transuranium elements and the superheavy elements are considered. (orig./HSI) [de

  9. Tunneling from super- to normal-deformed minima in nuclei

    International Nuclear Information System (INIS)

    Khoo, T. L.

    1998-01-01

    An excited minimum, or false vacuum, gives rise to a highly elongated superdeformed (SD) nucleus. A brief review of superdeformation is given, with emphasis on the tunneling from the false to the true vacuum, which occurs in the feeding and decay of SD bands. During the feeding process the tunneling is between hot states, while in the decay it is from a cold to a hot state. The γ spectra connecting SD and normal-deformed (ND) states provide information on several physics issues: the decay mechanism; the spin/parity quantum numbers, energies and microscopic structures of SD bands; the origin of identical SD bands; the quenching of pairing with excitation energy; and the chaoticity of excited ND states at 2.5-5 MeV. Other examples of tunneling in nuclei, which are briefly described, include the possible role of tunneling in ΔI = 4 bifurcation in SD bands, sub-barrier fusion and proton emitters

  10. Tunneling from super- to normal-deformed minima in nuclei.

    Energy Technology Data Exchange (ETDEWEB)

    Khoo, T. L.

    1998-01-08

    An excited minimum, or false vacuum, gives rise to a highly elongated superdeformed (SD) nucleus. A brief review of superdeformation is given, with emphasis on the tunneling from the false to the true vacuum, which occurs in the feeding and decay of SD bands. During the feeding process the tunneling is between hot states, while in the decay it is from a cold to a hot state. The {gamma} spectra connecting SD and normal-deformed (ND) states provide information on several physics issues: the decay mechanism; the spin/parity quantum numbers, energies and microscopic structures of SD bands; the origin of identical SD bands; the quenching of pairing with excitation energy; and the chaoticity of excited ND states at 2.5-5 MeV. Other examples of tunneling in nuclei, which are briefly described, include the possible role of tunneling in {Delta}I = 4 bifurcation in SD bands, sub-barrier fusion and proton emitters.

  11. Double-arm time-of-flight mass-spectrometer of nuclear fragments

    International Nuclear Information System (INIS)

    Ajvazian, G.M.; Astabatyan, R.A.

    1995-01-01

    A double-arm time-of-flight spectrometer of nuclear fragments for the investigation of heavy nuclei photofission in the intermediate energy range is described. The calibration results and working characteristics of the spectrometer, obtained using 252 Cf as a source of spontaneous fission, are presented. A mass resolution of σ m ∼2-3 a.m.u. was obtained within the registered fragments mass range of 80-160 a.m.u. The spectrometer was tested in the experiment on the investigation of 238 U nuclei fission by Bremsstahlung photons with Eγ max=1.75 GeV

  12. The mechanism of total disintegration of heavy nuclei by fast hadrons and nuclei

    International Nuclear Information System (INIS)

    Strugalska-Gola, E.; Strugalski, Z.

    1997-01-01

    The mechanism of the total disintegration of atomic nuclei by fast hadrons and nuclei is considered. The passage of energetic hadrons through layers of intranuclear matter, accompanied by emission of fast nucleons with kinetic energies from about 20 up to about 500 MeV from definite local small regions in the nuclei around projectile courses in them, allows one to explain simply the occurrence of the total destruction of nuclei involved in the collisions. Light nuclei may be totally disintegrated by fast hadrons and nuclei; heavier nuclei may be totally disintegrated only in central collisions of nuclei with similar mass numbers

  13. Modelling Hot Air Balloons.

    Science.gov (United States)

    Brimicombe, M. W.

    1991-01-01

    A macroscopic way of modeling hot air balloons using a Newtonian approach is presented. Misleading examples using a car tire and the concept of hot air rising are discussed. Pressure gradient changes in the atmosphere are used to explain how hot air balloons work. (KR)

  14. Archaeal diversity in Icelandic hot springs

    DEFF Research Database (Denmark)

    Kvist, Thomas; Ahring, Birgitte Kiær; Westermann, Peter

    2007-01-01

    Whole-cell density gradient extractions from three solfataras (pH 2.5) ranging in temperature from 81 to 90 degrees C and one neutral hot spring (81 degrees C, pH 7) from the thermal active area of Hveragerethi (Iceland) were analysed for genetic diversity and local geographical variation...... of Archaea by analysis of amplified 16S rRNA genes. In addition to the three solfataras and the neutral hot spring, 10 soil samples in transects of the soil adjacent to the solfataras were analysed using terminal restriction fragment length polymorphism (t-RFLP). The sequence data from the clone libraries...... enzymes AluI and BsuRI. The sequenced clones from this solfatara belonged to Sulfolobales, Thermoproteales or were most closest related to sequences from uncultured Archaea. Sequences related to group I.1b were not found in the neutral hot spring or the hyperthermophilic solfatara (90 degrees C)....

  15. Meson-exchange forces and medium polarization in finite nuclei

    International Nuclear Information System (INIS)

    Hengeveld, W.

    1986-01-01

    A G-matrix, derived from a meson-exchange potential in nuclear matter, is applied to finite, semi-magic nuclei. For the open shell the broken-pair model, which can accomodate many particle levels, is used. The excitations of the closed shell are treated as particle-hole states. Energy spectra and electromagnetic transition densities are calculated for 88 Sr and 58 Ni. The standard random-phase approximation for finite systems is extended by including the effects of the exchange of the RPA phonons in the residual interaction selfconsistently. It is shown that this particle-hole interaction is strongly energy dependent due to the presence of poles corresponding to 2p-2h (and more complex) excitations. The RPA eigenvalue problem with this energy-dependent residual interaction also provides solutions for these predominantly 2p2h-like states. In addition a modified normalization condition is obtained. This scheme is applied to 56 Ni( 56 Co) in a large configuration space using a residual interaction of the G-matrix type. The effect of dynamic medium polarization on the properties of giant resonances is illustrated for the case of A=48 nuclei. A large fragmentation of the monopole strength is calculated, which is in accordance with the non-observation of the GMR in light nuclei. Properties of A=48 nuclei are computed with an interaction deduced from the NN scattering data without introduction of additional parameters. The role of medium polarization is illustrated for spectra and (e,e') form factors. It is shown how medium polarization induces a coupling between excitations in even-even and in the adjacent odd-odd nuclei. (Auth.)

  16. Inclusive characteristics of the nuclear target fragmentation products induced by relativistic particles

    International Nuclear Information System (INIS)

    Bogatin, V.I.; Ganza, E.A.; Lozhkin, O.V.; Murin, Yu.A.; Oplavin, V.S.; Perfilov, N.A.; Yakovlev, Yu.P.

    1981-01-01

    An experimental investigation of inclusive characteristics of nuclei-target fragmentation is conducted for further development and test of physical value of the earlier suggested nuclear fragmentation model based on the connection of the fragmentation with fluctuations of the quasiparticle density in the two-component quantum liquid, an experimental investigation of the inclusive characteristics of the nuclei-target fragmentation is carried out. The processes of sup(3, 4, 6, 8)He and sup(6, 7, 8, 9, 11)Li fragment formation during the interaction of relativistic protons (Esub(p)=6.7 GeV) and deutrons (Esub(d)=3.1 GeV) with 112 Sn and 124 Sn isotopes are studied by the method of semiconductive ΔE-E detectors. Differential energy spectra of fragments and isotopic ratio of cross sections of their formation as well as data on the dependence of isotopic ratios of fragmentation cross sections on the energy of incident particles and on the fragment energy are obtained. Presented is a phenomenological model of fragmentation within the frames of which the obtained experimental data are analyzed [ru

  17. Fusion-fission of superheavy nuclei at low excitation energies

    International Nuclear Information System (INIS)

    Itkis, M.G.; Oganesyan, Yu.Ts.; Kozulin, E.M.

    2000-01-01

    The process of fusion-fission of superheavy nuclei with Z = 102 -122 formed in the reactions with 22 Ne, 26 Mg, 48 Ca, 58 Fe and 86 Kr ions at energies near and below the Coulomb barrier has been studied. The experiments were carried out at the U-400 accelerator of the Flerov Laboratory of Nuclear Reactions (JINR) using a time-of-flight spectrometer of fission fragments CORSET and a neutron multi-detector DEMON. As a result of the experiments, mass and energy distributions of fission fragments, fission and quasi-fission cross sections, multiplicities of neutrons and gamma-rays and their dependence on the mechanism of formation and decay of compound superheavy systems have been studied

  18. Transitional nuclei near shell closures

    Energy Technology Data Exchange (ETDEWEB)

    Mukherjee, G. [Variable Energy Cyclotron Centre, 1/AF Bidhan Nagar, Kolkata 700064 (India); Pai, H. [Variable Energy Cyclotron Centre, 1/AF Bidhan Nagar, Kolkata 700064, India and Present Address: Institut für Kernphysik, Technische Universität Darmstadt, Schlossgartenstrasse 9, 64289 Darmstadt (Germany)

    2014-08-14

    High spin states in Bismuth and Thallium nuclei near the Z = 82 shell closure and Cesium nuclei near the N = 82 shell closure in A = 190 and A = 130 regions, respectively, have been experimentally investigated using heavy-ion fusion evaporation reaction and by detecting the gamma rays using the Indian National Gamma Array (INGA). Interesting shape properties in these transitional nuclei have been observed. The results were compared with the neighboring nuclei in these two regions. The total Routhian surface (TRS) calculations have been performed for a better understanding of the observed properties. In mass region A = 190, a change in shape from spherical to deformed has been observd around neutron number N = 112 for the Bi (Z = 83) isotopes with proton number above the magic gap Z = 82, whereas, the shape of Tl (Z = 81) isotopes with proton number below the magic gap Z = 82 remains stable as a function of neutron number. An important transition from aplanar to planar configuration of angular momentum vectors leading to the occurance of nuclar chirality and magnetic rotation, respectively, has been proposed for the unique parity πh{sub 11/2}⊗νh{sub 11/2} configuration in Cs isotopes in the mass region A ∼ 130 around neutron number N = 79. These results are in commensurate with the TRS calculations.

  19. Cluster structure in Cf nuclei

    International Nuclear Information System (INIS)

    Singh, Shailesh K.; Biswal, S.K.; Bhuyan, M.; Patra, S.K.; Gupta, R.K.

    2014-01-01

    Due to the availability of advance experimental facilities, it is possible to probe the nuclei upto their nucleon level very precisely and analyzed the internal structure which will help us to resolve some mysterious problem of the decay of nuclei. Recently, the relativistic nuclear collision, confirmed the α cluster type structure in the 12 C which is the mile stone for the cluster structure in nuclei. The clustering phenomena in light and intermediate elements in nuclear chart is very interesting. There is a lot of work done by our group in the clustering behaviour of the nuclei. In this paper, the various prospectus of clustering in the isotopes of Cf nucleus including fission state is discussed. Here, 242 Cf isotope for the analysis, which is experimentally known is taken. The relativistic mean field model with well established NL3 parameter set is taken. For getting the exact ground state configuration of the isotopes, the calculation for minimizing the potential energy surface is performed by constraint method. The clustering structure of other Cf isotopes is discussed

  20. Nuclear astrophysics of light nuclei

    DEFF Research Database (Denmark)

    Fynbo, Hans Otto Uldall

    2013-01-01

    A review of nuclear astrophysics of light nuclei using radioactive beams or techniques developed for radioactive beams is given. We discuss Big Bang nucleosynthesis, with special focus on the lithium problem, aspects of neutrino-physics, helium-burning and finally selected examples of studies...

  1. Particle detection from oriented nuclei

    International Nuclear Information System (INIS)

    Wouters, J.; Moor, P. de; Schuurmans, P.; Severijns, N.; Vanderpoorten, W.; Vanneste, L.

    1992-01-01

    A survey is given of particle emission from nuclei that have been spin oriented by cryogenical means. Experiments and recent developments with detectors in the low temperature environment and their on-line application are reviewed. The most recent results are mentioned. Some phenomena to be unraveled in future studies are pointed out. (orig.)

  2. Rotational damping motion in nuclei

    International Nuclear Information System (INIS)

    Egido, J.L.; Faessler, A.

    1991-01-01

    The recently proposed model to explain the mechanism of the rotational motion damping in nuclei is exactly solved. When compared with the earlier approximative solution, we find significative differences in the low excitation energy limit (i.e. Γ μ 0 ). For the strength functions we find distributions going from the Wigner semicircle through gaussians to Breit-Wigner shapes. (orig.)

  3. Percolation and multifragmentation of nuclei

    International Nuclear Information System (INIS)

    Shmakov, S.Yu.; Uzhinskij, V.V.

    1989-01-01

    A method to build the 'cold' nuclei as percolation clusters is suggested. Within the framework of definite assumptions of the character of nucleon-nucleon couplings breaking resulting from the nuclear reactions as description of the multifragmentation process in the hadron-nucleus and nucleus-nucleus reactions at high energies is obtained. 19 refs.; 6 figs

  4. Octupole correlation effects in nuclei

    International Nuclear Information System (INIS)

    Chasman, R.R.

    1992-01-01

    Octupole correlation effects in nuclei are discussed from the point of view of many-body wavefunctions as well as mean-field methods. The light actinides, where octupole effects are largest, are considered in detail. Comparisons of theory and experiment are made for energy splittings of parity doublets; E1 transition matrix elements and one-nucleon transfer reactions

  5. Electron scattering for exotic nuclei

    Indian Academy of Sciences (India)

    2014-11-04

    Nov 4, 2014 ... A brand-new electron scattering facility, the SCRIT Electron Scattering Facility, will soon start its operation at RIKEN RI Beam Factory, Japan. This is the world's first electron scattering facility dedicated to the structure studies of short-lived nuclei. The goal of this facility is to determine the charge density ...

  6. Land fragmentation and production diversification

    NARCIS (Netherlands)

    Ciaian, Pavel; Guri, Fatmir; Rajcaniova, Miroslava; Drabik, Dusan; Paloma, Sergio Gomez Y.

    2018-01-01

    We analyze the impact of land fragmentation on production diversification in rural Albania. Albania represents a particularly interesting case for studying land fragmentation as the fragmentation is a direct outcome of land reforms. The results indicate that land fragmentation is an important driver

  7. Nuclei far from stability using exotic targets

    International Nuclear Information System (INIS)

    Wilhelmy, J.B.; Bentley, C.E.; Thomas, K.E.; Brown, R.E.; Flynn, E.R.; Van der Plicht, J.; Mann, L.G.; Struble, G.L.

    1981-01-01

    The meson factories such as the Los Alamos Meson Physics Facility have made possible high fluence medium energy proton beams that can be used for spallation reactions to produce macro quantities of unstable isotopes. Targets of over 10 g/cm 2 can be exposed to total fluence approaching 1 A-hour resulting in spallation yields in the 0.01-10 mg range for many isotopes of potential interest for nuclear structure studies. With the use of hot cell facilities, chemical processing can isolate the desired material and this coupled with subsequent isotope separation can result in usable quantities of material for nuclear target applicaton. With offstable isotopes are target materials, conventional nuclear spectroscopy techniques can be employed to study nuclei far from stability. The irradiation and processing requirements for such an operation, along with the isotope production possibilities, are discussed. Also presented are initial experiments using a 148 Gd (tsub(1/2) = 75a) target to perform the (p,t) reaction to extablish levels in the proposed double magic nucleus 146 Gd. (orig.)

  8. Cold transfer between deformed, Coulomb excited nuclei

    International Nuclear Information System (INIS)

    Bauer, H.

    1998-01-01

    The scattering system 162 Dy → 116 Sn has been examined at energies in the vicinity of the Coulomb barrier using the Heidelberg-Darmstadt Crystal Ball spectrometer combined with 5 Germanium-CLUSTER detectors. In order to study pairing correlations as a function of angular momentum cold events were selected in the 2n stripping channel by identifying and suppressing the dominant hot part of the transfer with the Crystal Ball. The CLUSTER detectors with their high γ-efficiency were used to identify the transfer channel and to resolve individual final states. Cross sections for the population of individual yrast states in a cold transfer reaction have been measured for the first time indicating the strong influence of higher transfer multipolarities. At small surface distances Coulomb-nuclear interferences were found to be responsible for the stronger decline of the population of higher yrast states in the transfer channel as compared to the Coulex channel. As a preparatory study for 2n transfer measurements between high spin yrast states in the backbending region of deformed nuclei the Coulomb excitation process in the crossing region of two bands in 162 Dy has been analyzed. The gross properties of the measured population probabilities could be interpreted in a simple band mixing model. (orig.)

  9. Centrifugal fragmentation of a dinuclear system in the process of its evolution toward a compound nucleus

    International Nuclear Information System (INIS)

    Volkov, V. V.

    2007-01-01

    The centrifugal fragmentation of a dinuclear system in the process of evolution toward a compound nucleus is examined. If the angular momentum in the collision of primary nuclei is quite high, centrifugal forces become dominant at the final stage of the evolution of the dinuclear system formed, causing the decay of this dinuclear system to two strongly asymmetric nuclear fragments. Experimental data in which this specific nuclear process manifests itself are presented. Centrifugal fragmentation makes it possible to reveal the cluster facet of the evolution of a dinuclear system toward a compound nucleus. The possibility of this fragmentation process is a logical consequence of the concept of a dinuclear system for the complete fusion of nuclei

  10. Isotopic resolution of fission fragments from 238U + 12C transfer and fusion reactions

    International Nuclear Information System (INIS)

    Caamano, M.; Rejmund, F.; Derkx, X.; Schmidt, K. H.; Andouin, L.; Bacri, C. O.; Barreau, G.; Benlliure, J.; Casarejos, E.; Fernandez-Dominguez, B.; Gaudefroy, L.; Golabek, C.; Jurado, B.; Lemasson, A.; Navin, A.; Rejmund, M.; Roger, T.; Shrivastava, A.; Schmitt, C.; Taieb, J.

    2010-01-01

    Recent results from an experiment at GANIL, performed to investigate the main properties of fission-fragment yields and energy distributions in different fissioning nuclei as a function of the excitation energy, in a neutron-rich region of actinides, are presented. Transfer reactions in inverse kinematics between a 238 U beam and a 12 C target produced different actinides, within a range of excitation energy below 30 MeV. These fissioning nuclei are identified by detecting the target-like recoil, and their kinetic and excitation energy are determined from the reconstruction of the transfer reaction. The large-acceptance spectrometer VAMOS was used to identify the mass, atomic number and charge state of the fission fragments in flight. As a result, the characteristics of the fission-fragment isotopic distributions of a variety of neutron-rich actinides are observed for the first time over the complete range of fission fragments. (authors)

  11. Heavy fragment radioactivity

    International Nuclear Information System (INIS)

    Silisteanu, I.

    1991-06-01

    The effect of collective mode excitation in heavy fragment radioactivity (HFR) is explored and discussed in the light of current experimental data. It is found that the coupling and resonance effects in fragment interaction and also the proper angular momentum effects may lead to an important enhancing of the emission process. New useful procedures are proposed for the study of nuclear decay properties. The relations between different decay processes are investigated in detail. We are also trying to understand and explain in a unified way the reaction mechanisms in decay phenomena. (author). 17 refs, 4 figs, 3 tabs

  12. Halo structure of strange particles in nuclei

    International Nuclear Information System (INIS)

    Akaishi, Yoshinori; Yamazaki, Toshimitsu.

    1997-01-01

    Some characteristic behaviors of hyperons in nuclei which have recently been revealed experimentally and theoretically are discussed with the emphasis on the repulsive part of the hyperon-nucleus interaction. The observed Σ 4 He nucleus is a bound state with J π = 0 + and T ≅ 1/2. Its nucleus-Σ potential derived from a realistic ΣN interaction is characterized by inner repulsion and a strong Lane term, which play important roles in forming the Σ-hypernuclear bound state. In 208 Pb a typical Coulomb-assisted bound state is expected, where Σ is trapped in the surface region by the nucleus-Σ potential with the aid of Coulomb and centrifugal interactions. In the double-strangeness (S=-2) sector, there is a possibility that the lightest double-Λ hypernucleus ΛΛ 4 H is abundantly populated by stopping Ξ - on 4 He. Its formation branching amounts to about 15%. A stopped Ξ - on 9 Be will also produce efficiently a variety of double-Λ hyperfragments. Discrete spectra of weak-decay pions from the fragments will provide a means of mass spectroscopy of double-Λ hypernuclei. In the S=-2 five-body system an excited state Ξ 5 H is predicted to appear with 'strangeness halo' and the ground state ΛΛ 5 H with almost pure ΛΛ component. (author)

  13. Complete photo-fragmentation of the deuterium molecule

    International Nuclear Information System (INIS)

    Weber, Thorsten; Czasch, Achim O.; Jagutzki, Ottmar; Muller, Alkis K.; Mergel, Volker; Kheifets, A.; Rotenberg, Eli; Meigs, George; Prior, Mike H.; Daveau, Sebastian; Landers, Allen; Cocke, C.L.; Osipov, Timur; Diez Muino, Ricardo; Schmidt-Bocking, Horst; Dorner, Reinhard

    2004-01-01

    All properties of molecules, from binding and excitation energies to their geometry, are determined by the highly correlated initial state wavefunction of the electrons and nuclei. Perhaps surprisingly, details of these correlations can be revealed by studying the break-up of these systems into their constituents. The fragmentation might be initiated by the absorption of a single photon [1, 2, 3, 4, 5, 6], collision with a charged particle [7, 8] or exposure to a strong laser pulse [9, 10]. If the exciting interaction is sufficiently understood, one can use the fragmentation process as a tool to learn about the bound initial state [11, 12]. However, often the interaction and the fragment motions pose formidable challenges to quantum theory [13, 14, 15]. Here we report the coincident measurement of the momenta of both nuclei and both electrons from the single photon induced fragmentation of the deuterium molecule. The results reveal that the correlated motion of the electrons is strongly dependent on the inter-nuclear separation in the molecular ground state at the instant of photon absorption

  14. Spontaneous fission of superheavy nuclei

    Indian Academy of Sciences (India)

    The fission-like configurations are used for the total deformation energy calculations. A ... oscillator potential for the two fission fragment regions reads as ... Beyond this limit, the contribution of more remote levels is negligible. Once the density ...

  15. Improvements to a model of projectile fragmentation

    International Nuclear Information System (INIS)

    Mallik, S.; Chaudhuri, G.; Das Gupta, S.

    2011-01-01

    In a recent paper [Phys. Rev. C 83, 044612 (2011)] we proposed a model for calculating cross sections of various reaction products which arise from disintegration of projectile-like fragments resulting from heavy-ion collisions at intermediate or higher energy. The model has three parts: (1) abrasion, (2) disintegration of the hot abraded projectile-like fragment (PLF) into nucleons and primary composites using a model of equilibrium statistical mechanics, and (3) possible evaporation of hot primary composites. It was assumed that the PLF resulting from abrasion has one temperature T. Data suggested that, while just one value of T seemed adequate for most cross-section calculations, a single value failed when dealing with very peripheral collisions. We have now introduced a variable T=T(b) where b is the impact parameter of the collision. We argue that there are data which not only show that T must be a function of b but, in addition, also point to an approximate value of T for a given b. We propose a very simple formula: T(b)=D 0 +D 1 [A s (b)/A 0 ] where A s (b) is the mass of the abraded PLF and A 0 is the mass of the projectile; D 0 and D 1 are constants. Using this model we compute cross sections for several collisions and compare with data.

  16. PELE fragmentation dynamics

    NARCIS (Netherlands)

    Verreault, J.; Hinsberg, N.P. van; Abadjieva, E.

    2013-01-01

    An analytical model that describes the PELE fragmentation dynamics is presented and compared with experimental results from literature. The model accounts for strong shock effects and detailed interactions taking place between the filling – the inner core of the ammunition – and the target

  17. Cryobiology of coral fragments.

    Science.gov (United States)

    Hagedorn, Mary; Farrell, Ann; Carter, Virginia L

    2013-02-01

    Around the world, coral reefs are dying due to human influences, and saving habitat alone may not stop this destruction. This investigation focused on the biological processes that will provide the first steps in understanding the cryobiology of whole coral fragments. Coral fragments are a partnership of coral tissue and endosymbiotic algae, Symbiodinium sp., commonly called zooxanthellae. These data reflected their separate sensitivities to chilling and a cryoprotectant (dimethyl sulfoxide) for the coral Pocillopora damicornis, as measured by tissue loss and Pulse Amplitude Modulated fluorometry 3weeks post-treatment. Five cryoprotectant treatments maintained the viability of the coral tissue and zooxanthellae at control values (1M dimethyl sulfoxide at 1.0, 1.5 and 2.0h exposures, and 1.5M dimethyl sulfoxide at 1.0 and 1.5h exposures, P>0.05, ANOVA), whereas 2M concentrations did not (Pzooxanthellae. During the winter when the fragments were chilled, the coral tissue remained relatively intact (∼25% loss) post-treatment, but the zooxanthellae numbers in the tissue declined after 5min of chilling (Pzooxanthellae numbers declined in response to chilling alone (P0.05, ANOVA), but it did not protect against the loss of zooxanthellae (Pzooxanthellae are the most sensitive element in the coral fragment complex and future cryopreservation protocols must be guided by their greater sensitivity. Copyright © 2012 Elsevier Inc. All rights reserved.

  18. Fragments of the Past

    OpenAIRE

    Peter Szende; Annie Holcombe

    2016-01-01

    With travel being made more accessible throughout the decades, the hospitality industry constantly evolved their practices as society and technology progressed. Hotels looked for news ways up service their customers, which led to the invention of the Servidor in 1918. Once revolutionary innovations have gone extinct, merely becoming fragments of the past.

  19. Synthesis of arabinoxylan fragments

    DEFF Research Database (Denmark)

    Underlin, Emilie Nørmølle; Böhm, Maximilian F.; Madsen, Robert

    , or production of commercial chemicals which are mainly obtained from fossil fuels today.The arbinoxylan fragments have a backbone of β-1,4-linked xylans with α-L-arabinose units attached at specific positions. The synthesis ultilises an efficient synthetic route, where all the xylan units can be derived from D...

  20. Fragmented Work Stories

    DEFF Research Database (Denmark)

    Humle, Didde Maria; Reff Pedersen, Anne

    2015-01-01

    stories. We argue that meaning by story making is not always created by coherence and causality; meaning is created by different types of fragmentation: discontinuities, tensions and editing. The objective of this article is to develop and advance antenarrative practice analysis of work stories...

  1. Fragments of the Past

    Directory of Open Access Journals (Sweden)

    Peter Szende

    2016-10-01

    Full Text Available With travel being made more accessible throughout the decades, the hospitality industry constantly evolved their practices as society and technology progressed. Hotels looked for news ways up service their customers, which led to the invention of the Servidor in 1918. Once revolutionary innovations have gone extinct, merely becoming fragments of the past.

  2. Cumulative protons in 12C fragmentation at intermediate energy

    International Nuclear Information System (INIS)

    Abramov, B.M.; Alekseev, P.N.; Borodin, Y.A.; Bulychjov, S.A.; Dukhovskoi, I.A.; Khanov, A.I.; Krutenkova, A.P.; Kulikov, V.V.; Martemianov, M.A.; Matsuk, M.A.; Turdakina, E.N.

    2014-01-01

    In the FRAGM experiment at heavy ion accelerator complex TWAC-ITEP, the proton yields at an angle 3.5 degrees have been measured in fragmentation of carbon ions at T 0 equals 0.3, 0.6, 0.95 and 2.0 GeV/nucleon on beryllium target. The data are presented as invariant proton yields on cumulative variable x in the range 0.9 < x < 2.4. Proton spectra cover six orders of invariant cross section magnitude. They have been analyzed in the framework of quark cluster fragmentation model. Fragmentation functions of quark- gluon string model are used. The probabilities of the existence of multi-quark clusters in carbon nuclei are estimated to be 8 - 12% for six-quark clusters and 0.2 - 0.6% for nine- quark clusters. (authors)

  3. On a calculation of nucleon knock-out cross sections in a collision of relativistic nuclei

    International Nuclear Information System (INIS)

    Goryachev, B.I.; Lin'kova, N.V.

    1985-01-01

    It is shown that in the framework of the two-stage model one can obtain knock-out cross sections of the given number of nucleons from the nucleus-target at a certain number of nucleons knocked out from the nucleus-projectile. The first stage is considered as a fast process of nucleon collisions of interacting nuclei which is completed with knock out of one or several nucleons. The second stage-comparatively slow - is related to de-excitation of nuclei-fragments

  4. Close correlation between the reaction mechanism and inner structure of loosely halo-nuclei

    International Nuclear Information System (INIS)

    Liu Jianye; Tianshui Normal Univ., Tianshui; National Laboratory of Heavy Ion Accelerator of Lanzhou, Lanzhou; Guo Wenjun; Ren Zhongzhou; National Laboratory of Heavy Ion Accelerator of Lanzhou, Lanzhou; Xing Yongzhong; National Laboratory of Heavy Ion Accelerator of Lanzhou, Lanzhou

    2006-01-01

    It was based on the comparisons of the variance properties of fragment multiplicities FM's and nuclear stoppings R's for the neutron-halo colliding system with those of FZ's and R's for the proton-halo colliding system with the increases of beam energy in more detail, the closely correlations between the reaction mechanism and the inner structures of halo-nuclei is found. From above comparisons it is found that the variance properties of fragment multiplicities and nuclear stopping with the increases of beam energy are quite different for the neutron-halo and proton halo colliding systems, such as the effects of loosely bound neutron-halo structure on the fragment multiplicities and nuclear stopping are obviously larger than those for the proton-halo colliding system. This is due to that the structures of halo-neutron nucleus 11 Li is more loosely than that of the proton-halo nucleus 23 Al. In this case, the fragment multiplicity and nuclear stopping of halo nuclei may be used as a possible probe for studying the reaction mechanism and the correlation between the reaction mechanism and the inner structure of halo-nuclei. (authors)

  5. Cavitation nuclei measurements - A review

    International Nuclear Information System (INIS)

    Billet, M.L.

    1985-01-01

    The measurement of cavitation nuclei has been the goal of many cavitation research laboratories and has resulted in the development of many methods. Two significantly different approaches have been developed. One is to measure the particulate-microbubble distribution by utilizing acoustical, electrical or optical methods. The other approach measures a liquid tension and a rate of cavitation events for a liquid in order to establish a cavitation susceptibility. Comparisons between various methods indicate that most methods are capable of giving an indication of the nuclei distribution. Measurements obtained in the ocean environment indicate an average of three bubbles per cubic centimeter are present; whereas, water tunnel bubble distributions vary from much less than one to over a hundred per cubic centimeter

  6. Phonon operators in deformed nuclei

    International Nuclear Information System (INIS)

    Soloviev, V.G.

    1981-01-01

    For the description of the excited states in deformed nuclei new phonon operators are introduced, which depend on the sign of the angular momentum projection onto the symmetry axis of a deformed nucleus. In the calculations with new phonons the Pauli principle is correctly taken into account in the two-phonon components of the wave functions. There is a difference in comparison with the calculation with phonons independent of the sign of the angular momentum projection. The new phonons should be used in deformed nuclei if the Pauli principle is consistently taken into account and in the calculations with the excited state wave functions having the components with more than one phonon operator [ru

  7. Phonon operators for deformed nuclei

    International Nuclear Information System (INIS)

    Solov'ev, V.G.

    1982-01-01

    The mathematical formalism with the phonon operators independent of the signature of the angular momentum projection turns out to be inadequate for describing excited states of deformed nuclei. New phonon operators are introduced which depend on the signature of the angular momentum projection on the symmetry axis of a deformed nucleus. It is shown that the calculations with the new phonons take correctly into account the Pauli principle in two-phonon components of wave functions. The results obtained differ from those given by the phonons independent of the signature of the angular momentum projection. The new phonons must be used in deformed nuclei at taking systematically the Pauli principle into account and in calculations involving wave functions of excited states having components with more than one-phonon operator

  8. Nuclear treasure island [superheavy nuclei

    CERN Document Server

    CERN. Geneva

    1999-01-01

    Summary form only given. Soon after the experiments at Dubna, which synthesized element 114 and made the first footprints on the beach of the "island of nuclear stability", two new superheavy elements have been discovered at the Lawrence Berkeley National Laboratory. Element 118 and its immediate decay product, element 116, were manufactured at Berkeley's 88 inch cyclotron by fusing targets of lead-208 with an intense beam of 449 MeV krypton-86 ions. Although both new nuclei almost instantly decay into lighter ones, the decay sequence is consistent with theories that have long predicted the island of stability for nuclei with approximately 114 protons and 184 neutrons. Theorist Robert Smolanczuk, visiting from the Soltan Institute for Nuclear Studies in Poland, had calculated that this reaction should have particularly favourable production rates. Now that this route has been signposted, similar reactions could be possible: new elements and isotopes, tests of nuclear stability and mass models, and a new under...

  9. Moessbauer effects on oriented nuclei

    International Nuclear Information System (INIS)

    Sayouti, E.H.

    1984-01-01

    Standard nuclear orientation methods (not sensitive to the polarization) do not give information on the sign of the magnetic moment. Mossbauer effect separates right-hand and left-hand circularly polarized components, thus its detection on oriented nuclei (T approximately 10 mK) gives the sign of the magnetic moment of oriented state. In this thesis we applied this method to study the 3/2 - ground states of 191 Pt and 193 Os, which are in the prolate-oblate transition region, where assignement of experimental levels to theoretical states is often umbiguous. We show that for those nuclei the sign of the magnetic moment is the signature of the configuration, and its determination establishes the correspondance between experimental and theoretical levels [fr

  10. Clusters in nuclei. Vol. 1

    International Nuclear Information System (INIS)

    Beck, Christian

    2010-01-01

    Following the pioneering discovery of alpha clustering and of molecular resonances, the field of nuclear clustering is presently one of the domains of heavy-ion nuclear physics facing both the greatest challenges and opportunities. After many summer schools and workshops, in particular over the last decade, the community of nuclear molecular physics decided to team up in producing a comprehensive collection of lectures and tutorial reviews covering the field. This first volume, gathering seven extensive lectures, covers the follow topics: - Cluster Radioactivity - Cluster States and Mean Field Theories - Alpha Clustering and Alpha Condensates - Clustering in Neutron-rich Nuclei - Di-neutron Clustering - Collective Clusterization in Nuclei - Giant Nuclear Molecules By promoting new ideas and developments while retaining a pedagogical nature of presentation throughout, these lectures will both serve as a reference and as advanced teaching material for future courses and schools in the fields of nuclear physics and nuclear astrophysics. (orig.)

  11. Mesons and quarks in nuclei

    International Nuclear Information System (INIS)

    Oset, E.

    1980-01-01

    A short review of the topic of mesons in nuclei is exposed paying particular attention to the relationship between several mesonic processes. Special emphasis is put into the microscopic pictures that can ultimately relate all these processes with the elementary coupling of mesons to the nuclear hadronic components. The importance of the short range part of the nuclear interaction opens the doors to a more basic understanding in terms of the quark components of nucleons and isobars. (orig.)

  12. Exclusive photoreactions on light nuclei

    International Nuclear Information System (INIS)

    Maruyama, K.

    1989-08-01

    The mechanism of photon absorption on light nuclei in the Δ-resonance region is discussed. The present status of experimental results is briefly summarized. A recent data from 1.3-GeV Tokyo ES using a π sr spectrometer is introduced. Exclusive measurements of the photodisintegration of 3 He and 4 He may be a clear way to identify 2N, 3N and 4N absorptions. (author)

  13. Fission barriers of light nuclei

    International Nuclear Information System (INIS)

    Grotowski, K.; Planeta, R.; Blann, M.; Komoto, T.

    1989-01-01

    Experimental fission excitation functions for compound nuclei /sup 52/Fe, /sup 49/Cr, /sup 46/V, and /sup 44/Ti formed in heavy-ion reactions are analyzed in the Hauser-Feshbach/Bohr-Wheeler formalism using fission barriers based on the rotating liquid drop model of Cohen et al. and on the rotating finite range model of Sierk. We conclude that the rotating finite range approach gives better reproduction of experimental fission yields, consistent with results found for heavier systems

  14. Hot spot detection for breast cancer in Ki-67 stained slides: image dependent filtering approach

    Science.gov (United States)

    Niazi, M. Khalid Khan; Downs-Kelly, Erinn; Gurcan, Metin N.

    2014-03-01

    We present a new method to detect hot spots from breast cancer slides stained for Ki67 expression. It is common practice to use centroid of a nucleus as a surrogate representation of a cell. This often requires the detection of individual nuclei. Once all the nuclei are detected, the hot spots are detected by clustering the centroids. For large size images, nuclei detection is computationally demanding. Instead of detecting the individual nuclei and treating hot spot detection as a clustering problem, we considered hot spot detection as an image filtering problem where positively stained pixels are used to detect hot spots in breast cancer images. The method first segments the Ki-67 positive pixels using the visually meaningful segmentation (VMS) method that we developed earlier. Then, it automatically generates an image dependent filter to generate a density map from the segmented image. The smoothness of the density image simplifies the detection of local maxima. The number of local maxima directly corresponds to the number of hot spots in the breast cancer image. The method was tested on 23 different regions of interest images extracted from 10 different breast cancer slides stained with Ki67. To determine the intra-reader variability, each image was annotated twice for hot spots by a boardcertified pathologist with a two-week interval in between her two readings. A computer-generated hot spot region was considered a true-positive if it agrees with either one of the two annotation sets provided by the pathologist. While the intra-reader variability was 57%, our proposed method can correctly detect hot spots with 81% precision.

  15. Hot Surface Ignition

    OpenAIRE

    Tursyn, Yerbatyr; Goyal, Vikrant; Benhidjeb-Carayon, Alicia; Simmons, Richard; Meyer, Scott; Gore, Jay P.

    2015-01-01

    Undesirable hot surface ignition of flammable liquids is one of the hazards in ground and air transportation vehicles, which primarily occurs in the engine compartment. In order to evaluate the safety and sustainability of candidate replacement fuels with respect to hot surface ignition, a baseline low lead fuel (Avgas 100 LL) and four experimental unleaded aviation fuels recommended for reciprocating aviation engines were considered. In addition, hot surface ignition properties of the gas tu...

  16. The creation of new nuclei

    International Nuclear Information System (INIS)

    Armbruster, P.; Hessberger, F.P.

    1998-01-01

    In the last 60 years physicists have created 20 artificial elements beyond uranium. In 1934 Enrico Fermi predicted the creation of new elements by bombarding atoms with neutrons. This method led to the discovery of neptunium (Z=93), plutonium, americium, curium, berkelium, californium, einsteinium and fermium (Z=100). In fact the capture of a neutron is followed by a beta-decay which increases the atomic number (Z) by one unit. Beyond Z=100 beta-decay no more occurs so a new approach was necessary. Between the American Lawrence Berkeley Laboratory and the Russian Dubna Institute a fierce competition broke out to produce new elements by bombarding transuranium nuclei with light elements such as helium, carbon, nitrogen. This new method required heavy equipment: ion accelerator and detectors but led to the creation of all the elements from Z=101 to Z=106. A new idea was to provoke the fusion of heavy nuclei such as lead and bismuth with colliding argon, nickel or zinc ion beams. This method called 'cold fusion' opened the way to reach the nuclei beyond Z=107. In 1996 the element Z=112 was the last discovered. The next step could be the element Z=114 for which a particular stability is expected. (A.C.)

  17. Density functional theory of nuclei

    International Nuclear Information System (INIS)

    Terasaki, Jun

    2008-01-01

    The density functional theory of nuclei has come to draw attention of scientists in the field of nuclear structure because the theory is expected to provide reliable numerical data in wide range on the nuclear chart. This article is organized to present an overview of the theory to the people engaged in the theory of other fields as well as those people in the nuclear physics experiments. At first, the outline of the density functional theory widely used in the electronic systems (condensed matter, atoms, and molecules) was described starting from the Kohn-Sham equation derived on the variational principle. Then the theory used in the field of nuclear physics was presented. Hartree-Fock and Hartree-Fock-Bogolyubov approximation by using Skyrme interaction was explained. Comparison of the results of calculations and experiments of binding energies and ground state mean square charge radii of some magic number nuclei were shown. The similarity and dissimilarity between the two streams were summarized. Finally the activities of the international project of Universal Nuclear Energy Density Functional (UNEDF) which was started recently lead by US scientist was reported. This project is programmed for five years. One of the applications of the project is the calculation of the neutron capture cross section of nuclei on the r-process, which is absolutely necessary for the nucleosynthesis research. (S. Funahashi)

  18. Exotic Nuclei and Yukawa's Forces

    International Nuclear Information System (INIS)

    Otsuka, Takaharu; Suzuki, Toshio; Utsuno, Yutaka

    2008-01-01

    In this plenary talk, we will overview the evolution of the shell structure in stable and exotic nuclei as a new paradigm of nuclear structure physics. This shell evolution is primarily due to the tensor force. The robust mechanism and some examples will be presented. Such examples include the disappearance of existing magic numbers and the appearance of new ones. The nuclear magic numbers have been believed, since Mayer and Jensen, to be constants as 2, 8, 20, 28, 50, ... This turned out to be changed, once we entered the regime of exotic nuclei. This shell evolution develops at many places on the nuclear chart in various forms. For example, superheavy magic numbers may be altered. Thus, we are led to a new paradigm as to how and where the nuclear shell evolves, and what consequences arise. The evolution of the shell affects weak process transitions, and plays a crucial role in deformation. The π and ρ mesons generate tensor forces, and are the fundamental elements of such intriguing phenomena. Thus, physics of exotic nuclei arises as a manifestation of Yukawa's forces

  19. The colours of Hubble Sc galaxy nuclei

    International Nuclear Information System (INIS)

    Iskudaryan, S.G.

    1975-01-01

    The colorimetric data on the nuclei of the Sc galaxies are given. Comparison of the following parameters: color of a nucleus, integral color of a galaxy, Byurakan class, and spectral type of normal spirals gives the possibility to conclude: (1) The colors of the nuclei of the Sc galaxies have a high dispersion in its values. In all Byurakan classes the galaxies with intensely red and blue nuclei occur; (2) Some Sc galaxies exhibit a discrepancy between the spectral and morphological types. The results of colorimetry of nuclei indicate that almost all such Sc galaxies have intensely red nuclei which, naturally, provide for these late spectral types. It can be assumed that the intensely red color of the nuclei of such Sc galaxies is a result of a new type of activity of these nuclei; and (3) some Sc galaxies show the characteristics of the Markarian objects

  20. Sub-fragmentation of structural-reactive-material casings under explosion

    Science.gov (United States)

    Zhang, Fan

    2015-06-01

    The sub-fragmentation of structural reactive material (SRM) thick-casings is to generate fine fragments during casing fragmentation under explosive loading for their efficient energy release to enhance air blast. This has been investigated using a cylindrical casing made from either rich Al-MoO3 or Al-W-based granular composites. The former composite was to study the concept of reactive hot spots where the reaction of reactive particles, which were distributed into base SRM in a fuel-rich equivalence ratio, created heat and gas products during SRM fragmentation. The expansion of these distributed hot spots initiated local fractures of the casing, leading to fine fragments. The Al-W-based composite investigated the concept of impedance mismatch, where shock dynamics at the interfaces of different impedance ingredients resulted in non-uniform, high local temperatures and stresses and late in times the dissimilar inertia resulted in different accelerations, leading to material separation and fine fragments. The casings were manufactured through both hot iso-static pressing and cold gas dynamic spray deposition. Explosion experiments were conducted in a 3 m diameter, 23 m3 cylindrical chamber for these cased charges in a casing-to-explosive mass ratio of 1.75. The results demonstrated the presence of fine fragments and more efficient fragment combustion, compared with previous results, and indicated the effectiveness of both concepts. This work was jointly funded by Defence R&D Canada and the Advanced Energetics Program of DTRA (Dr. William H. Wilson).