Spectroscopy of heavy nuclei: yrast states, side bands and backbending
International Nuclear Information System (INIS)
Sunyar, A.W.
1979-01-01
Some recent experimental results concerning the high spin structure of two rare earth nuclei are presented. These are 154 Er and 158 Dy. The level schemes including yrast sequences are discussed. The reactions 142 Nd( 16 O,4n) and 150 Nd( 13 C,5n) respectively, for the studied nuclei are noted. 14 references
Toward yrast spectroscopy in soft vibrational nuclei
International Nuclear Information System (INIS)
Marumori, Toshio; Kuriyama, Atsushi; Sakata, Fumihiko.
1979-10-01
In a formally parallel way with that exciting progress has been recently achieved in understanding the yrast spectra of the rotational nuclei in terms of the quasi-particle motion in the rotating frame, an attempt to understand the yrast spectra of the vibrational nuclei in terms of the quasi-particle motion is proposed. The essential idea is to introduce the quasi-particle motion in a generalized vibrating frame, which can be regarded as a rotating frame in the gauge space of ''physical'' phonons where the number of the physical phonons plays the role of the angular momentum. On the basis of a simple fundamental principle called as the ''invariance principle of the Schroedinger equation'', which leads us to the ''maximal decoupling'' between the physical phonon and the intrinsic modes, it is shown that the vibrational frame as well as the physical-phonon-number operator represented by the quasi-particles can be self-consistently determined. A new scope toward the yrast spectroscopy of the vibrational nuclei in terms of the quasi-particle motion is discussed. (author)
International Nuclear Information System (INIS)
Daly, P.J.
1981-01-01
The structure of nuclei in the A approx. 150 region was investigated by in-beam γ-ray spectroscopy using heavy-ion beams, mostly from the Argonne Tandem-Linac. Results for the nuclei 148 Dy, 149 Dy, 153 Dy, 154 Dy, 149 Ho, and 150 Ho are summarized. The feeding of yrast states in these nuclei and the link between the highest known yrast states and the continuum region were also studied. 6 figures
Spectroscopy high above the yrast line in rare earth nuclei
International Nuclear Information System (INIS)
Ramsoey, T.
1990-01-01
The particle-gamma coincidence technique presented in this work has proved to be a powerful tool in the study of nuclear structure. The most important feature is the ability to select well-defined excitation regions of entry states in a narrow spin window. The author has focused on the gamma-decay of low- lying descrete states and the gross structure properties in the region far above the yrast line. 6 refs., 5 figs
Systematic behavior of B(E2) values in the yrast bands of doubly even nuclei
International Nuclear Information System (INIS)
Andrejtscheff, W.; Rutgers - the State Univ., New Brunswick, NJ; Nadjakov, E.; Venkova, T.
1980-01-01
The experimental information on B(E2) transition rates in the yrast bands of doubly even nuclei (126 2 (J: moment of inertia) are plotted versus the rotational frequency squared h/2π 2 ω 2 for each nucleus. In strongly deformed nuclei (N >= 90), the Ssub(exp) curves smoothly increase for low rotational frequencies suggesting that up to spin values I approx. 8 the ratio Q 2 0 /J is nearly constant (Q 0 : quadrupole moment). This is not the case in nuclei with a soft core (N <= 88). In the relevant discussion, the hydrodynamical model as well as the CAP effect are considered. The results in the backbending region are qualitatively discussed in terms of the two-band crossing model. Evidence is found supporting the prediction of an oscillating behavior of the yrast-yrare interaction. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Hoellinger Fabien [Institut de Recherches Subatomiques, 23, Rue du Loess, BP 28, 67037 Strasbourg Cedex 2 (France)]|[Universite Louis Pasteur, 67 - Strasbourg (France)
1999-01-13
The nuclear structure study of neutron-rich nuclei was realized with the EUROGAM II array in two different experiments. The first study consisted in the analysis of the product of spontaneous fission of {sup 248}Cm. Three neutron-rich cerium isotopes {sup 147,149,151}Ce were analyzed. A level scheme for {sup 151}Ce is presented for the first time. The yrast structure of the three nuclei does not show alternative parity bands as expected in this region of octupole deformations. We studied the rotational structure of the bands and this leads to suggest Nilsson configurations to some of them. The aim of this second experiment was the study of the nuclei {sup 99}Mo, {sup 101}Tc, {sup 103}Ru. The three nuclei are situated on the neutron-rich side of the nuclear chart and are produced as fission fragments of a heavy-ion induced reaction. Some bands are extended to higher spins and some new bands are observed. The structure of the rotational bands is interpreted by means of the Hartree-Fock-Bogolyubov model. A last experiment intended to study the structure of the proton-rich nucleus {sup 223}Pa has been achieved with the JURO+RITU array located at Jyvaeskylae (Finland). In this proton-rich actinide region, the nuclei develop octupole features around Z{approx_equal}88, N{approx_equal}132. The analysis of this experiment leads to the first assignment of gamma transitions to the {sup 223}Pa. (author) 91 refs., 78 figs., 16 tabs.
International Nuclear Information System (INIS)
Marumori, Toshio; Kuriyama, Atsushi; Sakata, Fumihiko
1980-01-01
In a formally parallel way with that exciting progress has been recently achieved in understanding the yrast spectra of the rotational nuclei in terms of the quasi-particle motion in the rotating frame, an attempt to understand the yrast spectra of the vibrational nuclei in terms of the quasi-particle motion is proposed. The essential idea is to introduce the quasi-particle motion in a generalized vibrating frame, which can be regarded as a rotating frame in the gauge space of 'physical' phonons where the number of the physical phonons plays the role of the angular momentum. On the basis of a simple fundamental principle called as the 'invariance principle of the Schroedinger equation', which leads us to the 'maximal decoupling' between the physical phonon and the intrinsic modes, it is shown that the vibrational frame as well as the physical-phonon-number operator represented by the quasi-particles can be self-consistently determined. A new scope toward the yrast spectroscopy of the vibrational nuclei in terms of the quasi-particle motion is discussed
Studies of yrast and continuum states in A = 140 to 160 nuclei. Progress report for 1983
International Nuclear Information System (INIS)
Daly, P.J.
1983-12-01
The structure of nuclei, principally in the A-150 region, has been studied by in-beam γ-ray spectroscopy using heavy ion beams from the Argonne Tandem/Linac. New structural information was obtained for many shell model nuclei around 146 Gd, for the shape transitional nuclei 153 Dy and 154 Dy, and for the nuclei 147 Gd, 186 Hg, and 187 Hg at high-spin
Studies of yrast and continuum states in A = 100--200 nuclei
International Nuclear Information System (INIS)
Daly, P.J.
1992-02-01
This report summarizes progress in nuclear structure research for the year 1991. The highlights include new spectroscopic results for neutron excessive nuclei (around 124 Sn and 36 S) formed in deep inelastic heavy ion reactions
Studies of yrast and continuum states in A = 140 - 160 nuclei. Progress report for 1985
International Nuclear Information System (INIS)
Daly, P.J.
1986-02-01
The results of nuclear structure investigations by in-beam γ-ray spectroscopy following heavy ion reactions are summarized. Detailed information is given for the proton-rich nuclei 151 Tm, 152 Tm and 150 Ho, and for nuh/sub 11/2//sup n/ states in heavy tin isotopes. The first experiments performed with the new Compton-suppressed detector array at ATLAS are outlined
High-spin yrast states in the 206Po, 208Po, 209At and 210At nuclei
International Nuclear Information System (INIS)
Rahkonen, Vesa.
1980-08-01
High-spin yrast states in the 206 , 208 Po and 209 , 210 At nuclei have been studied with methods of in-beam γ-ray and conversion-electron spectroscopy and with the (α,3n), (α,4n), (p,2n) and ( 3 He,3n) reactions. Several new high-spin states have been identified up to angular momenta of 18-19 h/2π in these nuclei except in 206 Po where the highest spin was (13 - ). In the course of this work two new isomers with half-lives of 15+-3 ns and 4+-2 μs have been observed at 1689 and 4028 keV in 210 At, which have been interpreted as (10 - ) and 19 + states. The previously-known half-lives of 29+-2 and 680+-75 ns have been established for the three-proton states of Jsup(π)=21/2 - and 29/2 + at 1428 and 2429 keV in 209 At, respectively. A half-life of 1.0+-0.2 μs was measured for the 9 - isomer in 206 Po. Shell-model calculations based on the use of the empirical single- and two-particle interaction energies or of the experimental excitation energies belonging to the relevant one-, two- and three-particle states, have been carried out for these 4-6 particle nuclei. Most of the medium-spin yrast states in 206 Po, 208 Po and 209 At have been successfully described assuming the core for these nuclei being 204 Pb or 206 Pb rather than 208 Pb, and including an extra core polarization interaction described by the P 2 force. (author)
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)
Microscopical structure of the states of deformed nuclei in the neighborhood of the yrast line
International Nuclear Information System (INIS)
Janssen, D.; Mikhailov, I.N.
1979-01-01
A simple model is derived which allows one to study the structure of the nuclear states in the neighborhood of the 'yrast' band. In the present scheme the precession motion plays a role of one of the normal modes of oscillations. (The structure of the dispersion equation for this mode corresponds to the well known classical formula.) Vibrational states associated with quadrupole oscillations of the nuclear shape are determined from a general equation. At slow rotation this equation breaks up into the known equations for β-, Δ- and γ-vibrations and non-collectivized Ksup(π)=1 + excitations. (Auth.)
Lifetime measurements in the yrast band of the gamma-soft nuclei ...
Indian Academy of Sciences (India)
2016-06-15
Jun 15, 2016 ... ... J. Phys. (2016) 87: 7 c Indian Academy of Sciences ... +j. 1. Introduction. Shape deformations in nuclei are related to the gen- eral phenomenon of ... properties of various orbitals in which the nucleons move. Nuclei in the ...
Prediction of energies of yrast band in some even-even nuclei
International Nuclear Information System (INIS)
Varshney, A.K.; Singh, Yuvraj; Gupta, D.K.; Singh, M.; Gupta, K.K.; Bihari, Chhail; Dhiman, S.K.
2012-01-01
The deformation parameter β and γ of the collective model of Bohr and Mottelson are basic descriptors of the nuclear equilibrium shape and structure. The researchers found that the values of γ obtained from energies (= γ e ) are nearly equal to the value of γ derived from transition rate (= γ b ) in even Xe, Ba and Ce nuclei (A∼120-140) and Hf, W, Os, Pt and Hg nuclei (A∼160-200) using rigid triaxial rotor model of Davydov-Filippov. In the present study, the relatively light mass nuclei (Mo, Ru and Pd) have been taken. As far as γ is concerned, it is known that the Ru chains of nuclei is intermediate between the two having opposite trends for parameter γ, decreasing for Mo and increasing for Pd, and has an irregular behaviour in itself with the increase of neutron number
Projected shell model study of yrast states of neutron-deficient odd-mass Pr nuclei
International Nuclear Information System (INIS)
Ibanez-Sandoval, A.; Ortiz, M. E.; Velazquez, V.; Galindo-Uribarri, A.; Hess, P. O.; Sun, Y.
2011-01-01
A wide variety of modern instruments allow us to study neutron-deficient nuclei in the A=130 mass region. Highly deformed nuclei have been found in this region, providing opportunities to study the deformed rotational bands. The description of the 125,127,129,131,133 Pr isotopes with the projected shell model is presented in this paper. Good agreement between theory and experiment is obtained and some characteristics are discussed, including the dynamic moment of inertia J (2) , kinetic moment of inertia J (1) , the crossing of rotational bands, and backbending effects.
Nuclear structure far above the yrast line
International Nuclear Information System (INIS)
Gaardhoeje, J.J.
1985-01-01
The phase space available for gamma ray spectroscopic studies has recently been extended significantly with the observation of gamma radiation produced in the decay of highly collective (isovector) giant dipole resonances (GDR), built on excited states of high spin, in nuclei produced in heavy ion induced fusion reactions. These gamma rays are predominantly emitted in competition with particles in the first few steps of the decay of compound systems and constitute an entirely new tool to study nuclei at excitation energies far above the yrast line. Some problems of current central interest are addressed. (Auth.)
Studies of yrast and continuum states in A = 140-160 nuclei: Progress report for 1987
International Nuclear Information System (INIS)
Daly, P.J.
1988-02-01
High-spin nuclear phenomena in the mass region around A-150 have been studied by in-beam γ-ray and electron spectroscopy. Recent results for the nuclei 148 Gd, 149 Er, 152 Dy and 154 Dy are summarized. The first in-beam experiments at ATLAS using the Purdue superconducting electron spectrometer are also described. 11 refs., 2 figs
Nucleon transfer between heavy nuclei
International Nuclear Information System (INIS)
Von Oertzen, W.
1984-02-01
Nucleon transfer reactions between heavy nuclei are characterized by the classical behaviour of the scattering orbits. Thus semiclassical concepts are well suited for the description of these reactions. In the present contribution the characteristics of single and multinucleon transfer reactions at energies below and above the Coulomb barrier are shown for systems like Sn+Sn, Xe+U and Ni+Pb. The role of the pairing interaction in the transfer of nucleon pairs is illustrated. For strong transitions the coupling of channels and the absorption into more complicated channels is taken into account in a coupled channels calculation
Off-Yrast low-spin structure of deformed nuclei at mass number A∼150
Energy Technology Data Exchange (ETDEWEB)
Krugmann, Andreas
2014-07-14
The present work consists of two independent parts. The first part deals with the investigation of the 0{sup +}{sub 1}→0{sup +}{sub 2} transition in {sup 150}Nd with inelastic electron scattering and in the second part a proton scattering experiment for the investigation of dipole excitations is presented. In the first part of this thesis a pioneer experiment in inelastic electron scattering is introduced. At an electron energy of 75 MeV, excitation energy spectra have been measured at the high resolution 169 spectrometer at the S-DALINAC. The aim of this investigation was the determination of the ρ{sup 2}(E0;0{sup +}{sub 1}→0{sup +}{sub 2}) transition strength in the heavy deformed nucleus {sup 150}Nd. The experimental form factor of this particular transition has been compared to a theoretical form factor that has been constructed by an effective density operator on a microscopic level with the help of the generator coordinate method. The required collective wave functions have been calculated in the Confined β soft rotor model. In this model-dependent analysis the E0 transition strength has been determined for the first time. Furthermore the evolution of the E0 transition strength as a function of the potential stiffness has been investigated from the X(5) phase shape transitional point to the Rigid Rotor limit. It has been shown, that the E0 strength is relatively high at the shape-phase transitional point and starts to decrease with increasing stiffness and vanishes completely at the Rigid Rotor limit. Additionally the wave functions of the macroscopic collective Confined β-soft rotor model have been compared to those from a microscopic mean field Hamiltonian. Good agreement has been found. The second part of this thesis covers a polarized-proton scattering experiment on the heavy deformed nucleus {sup 154}Sm, that has been performed at the RCNP in Osaka, Japan. Utilizing the method of polarization transfer observables, a separation of spinflip and non
Electro-magnetic properties of heavy nuclei
International Nuclear Information System (INIS)
Otsuka, Takaharu
1989-01-01
Two topics of electro-magnetic properties of heavy nuclei are discussed. The first topic is the M1 excitation from well-deformed heavy nuclei, and the other is the sudden increase of the isotope shift as a function of N in going away from the closed shell. These problems are considered in terms of the particle-number projected (Nilsson-) BCS calculation. (author)
International Nuclear Information System (INIS)
Zhang Chengteng.
1993-12-01
In in-beam experiments using the γ-spectrometers Nordball at the Niels Bohr Institute and Osiris at the Hahn-Meitner Institute we populated the four N = 84 isotones 151 Ho, 152 Er, 153 Tm and 154 Yb through compound evaporation reactions induced with medium HI beams of masses ranging from 28 to 56. All observed γ-transitions with intensities above 1% (5% in 154 Yb) of the respective exit channel were placed in the level schemes, with spins established up to 10 MeV (8 MeV for 154 Yb) and parties up to between 5 and 7 MeV. We have found that in these N = 84 nuclei the multi-valence particle configurations πh n 11/2 νf 2 7/2 and πh n 11/2 νf 7/2 h 9/2 are strongly populated in the yrast cascades, and we have observed them up to their maximum spins of 43/2 - in Ho (at 4.8 MeV), 24 + in Er (7.5 MeV), 51/2 - in Tm (6.9 MeV), and only up to 24 + in Yb, 0.5 MeV below the fully aligned 26 + state expected at 9.1 MeV. The πh n νf 2 configuration forms smooth sections of the yrast line, while the more irregular yrast line of the πh n νfh character reflects the strong (νfh)8 + two-body attraction which gives rise to pronounced yrast line dips. We have also carried out full shell model calculations of these yrast lines, which are in excellent agreement with the experimental data. Since we take all dynamic input values, i.e. the two-body matrix elements and the single particle energies, from experiment, the calculations are free of any adjusted parameter. An interesting new result is the systematic identification in the πh n 11/2 νfh configuration of yrast states formed by specific proton couplings, where the strongly attractive (πh 11/2 νh 9/2 )1 + interaction is activated. As a consequence these states drop down to the yrast lines and in energy below the maximum aligned state of the next lower proton seniority. These seniority inverted yrast states were systematically identified in the four N = 84 nuclei, including two such states in 153 T, the first N 84
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.
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
Decay of heavy and superheavy nuclei
Indian Academy of Sciences (India)
April 2014 physics pp. 705–715. Decay of heavy and superheavy nuclei ... study on the feasibility of observing α decay chains from the isotopes of the ... studies on 284−286115 and 288−292117 will be a guide to future experiments. .... ratio of the α decay from the ground state of the parent nucleus to the level i of the.
From heavy nuclei to super-heavy nuclei; Des noyaux lourds aux super-lourds
Energy Technology Data Exchange (ETDEWEB)
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)
Nuclei at HERA and heavy ion physics
International Nuclear Information System (INIS)
Gavin, S.; Strikman, M.
1995-01-01
Copies of 16 viewgraph sets from a workshop held at Brookhaven National Laboratory, 17-18 November, 1995. Titles of talks: HERA: The Present; HERA: Potential with Nuclei; Review of Hadron-Lepton Nucleus Data; Fermilab E665: results in muon scattering; Interactions of Quarks and Gluons with Nuclear Matter; Rescattering in Nuclear Targets for Photoproduction and DIS; Structure Functions and Nuclear Effect at PHENIX; Probing Spin-Averaged and Spin-Dependent Parton Distributions Using the Solenoidal Tracker at RHIC (STAR); Jet Quenching in eA, pA, AA; Nuclear Gluon Shadowing via Continuum Lepton Pairs; What can we learn from HERA with a colliding heavy ion beam? The limiting curve of leading particles at infinite A; Coherent Production of Vector Mesons off Light Nuclei in DIS; A Model of High Parton Densities in PQCD; Gluon Production for Weizaecker-Williams Field in Nucleus-Nucleus Collisions; Summary Talk
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
Spectroscopy of very heavy nuclei with a view to study super-heavy nuclei
International Nuclear Information System (INIS)
Khalfallah, F.
2007-08-01
Within the recent years, the spectroscopic study of single particle orbitals of very heavy elements (VHE) has become possible with the development of increasingly efficient experimental setups. This allows us, through nuclear deformation, to access with these deformed nuclei to orbitals situated around the Fermi level in the spherical superheavy elements (SHE) and learn more about the nuclear structure of these nuclei. The aim of this work is the spectroscopic studies of heavy and very heavy elements. Because of the experimental difficulties associated with the fusion reactions in the VHE region, a detailed optimization studies is essential. Simulation of energy loss and angular straggling of these nuclei due to the interaction in the target and to neutron's evaporation was carried out and allowed us to optimize the angular acceptance of the separators according to the target thickness. An extensive survey and exploration in the VHE region was also conducted on the basis of cross section's systematics in the literature and simulations carried out using the statistical code Hivap. In this framework, the possible extension of the range of validity of a set of Hivap parameters was investigated. This work has enabled us to prepare a list of experiments of interest for the production of very heavy nuclei. In this thesis, our work was concentrated on the spectroscopy of the nuclei No 256 et Rf 256 for which two experimental proposals were accepted. The octupole deformations predicted in the actinides region is studied in another part of this thesis, a part witch is dedicated to the gamma spectroscopy of Pa 223 . The data from a new experiment carried out using the Jurogam-Ritu-Great setup are analysed and compared to previous results. They confirm the octupole deformed shape in this nucleus. (author)
Heavy accelerated nuclei in biomedical research
International Nuclear Information System (INIS)
Tobias, C.A.
1987-01-01
Accelerated atomic nuclei in physics accelerators have been used in basic biological research and in applied medical diagnostic and therapeutic studies for the past 50 years. The passage of single heavy particles through the cell nucleus is capable of producing multiple DNA double-strand scission and chromatin breaks. According to the Repair-Misrepair model, the high biological effectiveness of high-LET particles is due to misrepair and misrejoining of the breaks. The Bragg depth ionization effect allows heavy particles to deposit considerably more energy deep in tissue than at the surface, and this property has been used for great improvements in the radiation therapy of localized tumors. Recent advances in producing radioactive beams will allow verification of therapeutic administration of such beams. The radioactive beams also open a new field of Nuclear Medicine. There is increasing interest in building special biomedical light and heavy-ion accelerators. These will be used not only for therapy but also for diagnosis, for the study of radiation hazards in space flight, and for basic molecular and cellular understanding of the mechanisms of radiation effect
Heavy quarkonium production and propagation in nuclei
International Nuclear Information System (INIS)
Wong, C.Y.
1997-01-01
In the search for the quark-gluon plasma, it has been suggested that the production of charmonium will be suppressed in a quark-gluon plasma because of the screening of the interaction between c and anti c. To extract information on the suppression due to the quark-gluon plasma, it is necessary to study the suppression of J/ψ production by sources different from the quark-gluon plasma. It is therefore useful to examine the mechanism of heavy quarkonium production and its propagation in nuclei. The authors describe a precursor in heavy quarkonium production in terms of a coherent admixture of states of different color, spin, and angular momentum quantum numbers, and obtain the production amplitudes for different quarkonium bound states by projecting out this precursor state onto these bound states. The precursor is absorbed in its passage through a nucleus in a pA reaction, and the total cross section between this precursor with a nucleon can be calculated with the two-gluon model of the Pomeron. Such a description of coherent precursors and their subsequent interactions with nucleons can explain many salient features of J/ψ and ψ' production in pA collisions
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
International Nuclear Information System (INIS)
El Zaiki, M.I.; Nafie, H.O.; Abd El Mageed, K.E.
1992-01-01
Two methods of calculations have been used to fit the previously presented data on rotationally aligned quasiparticle bands in sup(160,162,164,166)Yb. Backbendings of moment of inertia of the Yrast states can be reproduced reasonably well. The energy levels and the effective moment of inertia for both gs and s-band are calculated and compared with the experimental data. Band crossing interpretations are discussed for each nucleus. The interaction strength calculations are presented. (author). 17 refs., 7 figs., 4 tabs
Decay of giant resonance E2 isoscalar in heavy nuclei
International Nuclear Information System (INIS)
Herdade, S.B.
1980-01-01
In this work, it is made a study of the giant resonance E2 isoscalar, in heavy nuclei. Fission probabilities for this resonance were determined by various authors, in different experiments, for 238 U. (A.C.A.S.) [pt
Prolate yrast cascade in 183Tl
International Nuclear Information System (INIS)
Reviol, W.; Carpenter, M. P.; Janssens, R. V. F.; Jenkins, D.; Toth, K. S.; Bingham, C. R.; Riedinger, L. L.; Weintraub, W.; Cizewski, J. A.; Lauritsen, T.
2000-01-01
The yrast sequence in 183 Tl has been studied for the first time in recoil-mass selected γ-ray spectroscopic measurements. A rotational-like cascade of seven transitions is established down to the band head with probable spin and parity (13/2 + ). Unlike in the adjacent odd-mass Tl nuclei, prompt γ decay from the yrast band to a lower lying weakly deformed (oblate) structure is not observed. These features are consistent with the predicted drop of the prolate band head in 183 Tl compared to 185 Tl. The implications for the prolate energy minimum in odd-mass Tl nuclei at the neutron i 13/2 midshell (N=103) are discussed. (c) 2000 The American Physical Society
Cluster radioactivity of Z=125 super heavy nuclei
International Nuclear Information System (INIS)
Manjunatha, H.C.; Seenappa, L.
2015-01-01
For atomic numbers larger than 121 cluster decay and spontaneous fission may compete with α decay. Hence there is a need to make reliable calculations for the cluster decay half-lives of superheavy nuclei to predict the possible isotopes super heavy nuclei. So, in the present work, we have studied the decay of clusters such as 8 Be, 10 Be, 12 C, 14 C, 16 C, 18 O, 20 O, 22 Ne, 24 Ne, 25 Ne, 26 Ne, 28 Mg, 30 Mg, 32 Si, 34 Si, 36 Si, 40 S, 48 Ca, 50 Ca and 52 Ti from the super heavy nuclei Z=125
Observation of the Antimatter Nuclei in Relativistic Heavy Ion Collisions
International Nuclear Information System (INIS)
Yoo, I.-K.
2013-01-01
Recently antimatter hyper-triton nuclei ( 3 Λ¯ H ¯) and antimatter helium nuclei ( 4 2 He ¯ ) are discovered with the Solenoidal Tracker At RHIC detector in relativistic heavy ion collisions at Relativistic Heavy Ion Collider (RHIC) (STAR Collaboration in Science 328(5974):58-62, 2010; STAR Collaboration in Nature 473:353-356, 2011). In this presentation, discoveries of antimatter particle are historically scanned and the recent observations at RHIC are reported in details as well as potential possibilities of discovery of antimatter nuclei at ALICE. (author)
Investigation of octupole deformations in the Fr217 nucleus by yrast spectroscopy
International Nuclear Information System (INIS)
Hulne, S.
1988-01-01
The spectroscopic characteristics of the yrast levels of Fr217 are determined. The level scheme up to a value of J = (39/2 + ) for angular momentum and parity is established. The production of the Fr217 nucleus in a heavy ion collision reaction was only possible by using a radioactive Pb210 target. The method for preparing the target is described. The Fr217 nucleus belongs to the category of nuclei showing octupole effects. Mass A = 217 seems to be the lower limit of the region where these effects occur [fr
Isospin Conservation in Neutron Rich Systems of Heavy Nuclei
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.
A note on total muon capture rates in heavy nuclei
International Nuclear Information System (INIS)
Parthasarathy, R.
1978-03-01
The results of calculations of the total capture rates in heavy nuclei, into account the nucleon velocity-dependent terms in the Fujii-Primakoff Hamiltonian and the effective mass of nucleons inside the nucleus, are presented along with the recent experimental data. The results are in general agreement with experiment. However, they indicate a possible deviation from SU(4) symmetry and, in some nuclei, support the Salam-Strathdee idea of the vanishing of the Cabibbo angle at large magnetic fields.
On deuteron break-up at interaction with heavy nuclei
International Nuclear Information System (INIS)
Evlanov, M.V.; Nemets, O.F.; Struzhko, B.G.
1975-01-01
The aim of the paper is the study of the nuclear boundary diffusivity during disintegration of a deutron on heavy nuclei for various combinations of neutron and proton emission angles. The formulae has obtained for the cross section and the amplitude of nuclear interaction. The calculation of angular correlations between emission directions of deutron disintegration products and energy spectra of released protons depending on the nuclear boundary diffusivity is made. It is shown that the differential cross sections of deutron fission disintegration decrease with increasing nuclear boundary diffusivity. This effect may serve a qualitative explanation for observed differences in the deutron disintegration cross sections on heavy nuclei
Heavy nuclei, from RHIC to the cosmos
International Nuclear Information System (INIS)
Klein, Spencer R.
2003-01-01
Ultra-relativistic heavy ion collisions produce a high-temperature, thermalized system that may mimic the conditions present shortly after the big bang. This writeup will given an overview of early results from the Relativistic Heavy Ion Collider (RHIC), and discuss what we have learned about hot, strongly interacting nuclear systems. The thermal and chemical composition of the system will be discussed, along with observables that are sensitive to the early evolution of the system. I will also discuss the implications of the RHIC results for cosmic ray air showers
Photofissility of heavy nuclei at intermediate energies
International Nuclear Information System (INIS)
Deppman, A.; Arruda Neto, J.D.T.; Likhachev, V.P.; Goncalves, M.
2002-10-01
We use the recently developed MCMC/MCEF (Multi Collisional Monte Carlo plus Monte Carlo for Evaporation-Fission calculations) model to calculate the photo fissility and the photofission cross section at intermediate energies for the 243 Am and for 209 Bi, and compare them to results obtained for other actinides and to available experimental data. As expected, the results for 243 Am are close to those for 237 Np. The fissility for pre actinide nuclei is nearly one order of magnitude lower than that for the actinides. Both fissility and photofission cross section for 209 Bi are in good agreement with the experimental data. (author)
French contribution to the super-heavy nuclei discovery
International Nuclear Information System (INIS)
Nifenecker, H.; Asghar, M.
1999-01-01
The research on super-heavy nuclei is a science in full operation for which the Berkeley physicist give proof of perseverance. The author wonders about the french absence in this domain. He recalls the strategical decisions concerning the research programs of the period and gives outline of the future with the interest of the ECR (Electronic Cyclotron Resonance) sources. (A.L.B.)
Transport theory of deep-inelastic collisions between heavy nuclei
International Nuclear Information System (INIS)
Ayik, S.; Noerenberg, W.; Schuermann, B.
1975-01-01
In collisions between heavy nuclei, the major part of the total cross-section is due to deep-inelastic processes. These processes have been studied within a quantum-statistical approach leading to transport equations of the Fokker-Planck type (generalized diffusion equation). Transport coefficients have been studied within a model. (orig./WL) [de
Recent studies of heavy nuclei far from stability at JYFL
Energy Technology Data Exchange (ETDEWEB)
Julin, R.; Enqvist, T.; Helariutta, K. [Univ. of Jyvaeskylae (Finland)] [and others
1996-12-31
The new K=130 Cyclotron + ECR facility of the Physics Department of the University of Jyvaskyla (JYFL) provides stable beams from protons up to krypton ions for nuclear structure studies. Two instruments designed especially for in-beam spectroscopic studies of heavy nuclei at JYFL are introduced in this contribution. Some results from recent measurements with them are reported.
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
Yrast spectroscopy: status of yrast isomers, oblate shapes and feeding of yrast states
International Nuclear Information System (INIS)
Khoo, T.L.
1980-01-01
The properties of very-high-spin states at the yrast line are addressed. Three different but related topics are discussed: the status of yrast isomers (mainly in the A approx. 150 region); the nuclear shape along the yrast line; and the feeding of the yrast states as a function of spin. A recurrent theme is the response of the core to the polarizing effects of a successively increasing number of valence particles and how the investigation of very-high-spin states bears on this problem. 10 figures, 1 table
Deep inelastic collisions between very heavy nuclei
International Nuclear Information System (INIS)
Sann, H.; Olmi, A.; Civelekoglu, Y.
1977-01-01
A systematic survey of deep inelastic reactions was performed for colliding nuclei of masses between 80 and 240 amu. The application of large surface detectors and, particularly, of a position sensitive ionization chamber, has proved to be very effective and appropriate for this type of investigation. The Wilczynski diagrams describing the relative motion between the colliding objects shows a gradual trend as a function of growing masses of target and projectile where the trajectories lead the particles not toward negative scattering angles but increasingly into the direction around and above the grazing angle. This behavior is attributed to a delicate balance between Coulomb and nuclear forces. The energy dumping as a function of the mass transfer strength matches a general law between total kinetic energy loss and the variance of the proton number distribution. For the partly damped component this relation seems to hold independently from the choice of ingoing channel and bombarding energy. The dissipation of the kinetic energy does not depend only on the relative velocity of the impinging nuclei, and the simple friction model is not appropriate to describe these processes. The γ-multiplicity measurement displays a rapid increase as a function of scattering angle and total kinetic energy loss, which give new insights to the process and indicate the necessity of microscopic quantum mechanical calculations of the interaction. In the U-U collision large mass transfers are present which possibly populate with relatively large cross sections the transuranic elements. In the Pb-Pb reaction the mass transfer is more restricted. The decay probability by fission of the primary masses increases strongly for growing masses and excitation energies
Collisions between heavy nuclei near the barrier
International Nuclear Information System (INIS)
Henning, W.
1988-05-01
Detailed information has recently become available on the reaction behavior in very heavy nuclear systems close to the Coulomb barrier. Starting from an experimental study of the distribution of the reaction strength above and below the barrier, the dominant reaction channels of quasi-elastic and strongly-damped processes are examined. With decreasing incident energy, the sub-barrier collisions are increasingly dominated by quasi-elastic processes. From the division of internal excitation energy, new information is obtained on the nature of the dissipative processes. (orig.)
Search for nuclei in heavy ion collisions at ultrarelativistic energies
2002-01-01
We would like to know if nuclei are still present after a collision of two heavy ions at ultrarelativistic energies. If one can detect some of them at large angle $(>10^{\\circ}-15^{\\circ})$ they very likely come from a multifragmentation of the excited target spectators. Such a multifragmentation in several nuclei has been in proton induced reactions at Fermilab and it was interpreted as a gas-liquid phase transition in nuclei matter near the critical point. With heavy ions the energy deposited in the target spectators will be much higher than in the case of protons and a different mechanism should be involved if nuclei are still observed. \\\\ \\\\ We propose to detect nuclei using 1-2 silicon telescopes and a 1-2mg/cm$^{2}$ Au target bombarded by an $^{16}$O or $^{32}$S beam at 226 GeV/u. The set-up will be installed in a small cube located just before the NA38 experiment and should not perturb it.\\\\ \\\\ Data from $^{16}$O incident on Au have been taken last year. The experiment is presently taking data with $^{...
Hadronic spectra from collisions of heavy nuclei
International Nuclear Information System (INIS)
Jacobs, P.
1997-03-01
Hadronic spectra from collisions of heavy ions at ultrarelativistic energies are discussed, concentrating on recent measurements at the SPS of central Pb+Pb collisions at 158 GeV/nucleon, which are compared to collisions of lighter ions and at lower beam energies. Baryon stopping is seen to be larger for heavier systems and lower energies. Total yields of pions and kaons scale with the number of participants in central collisions at the SPS; in particular, the K/π ratio is constant between central S+S and Pb+Pb at the SPS. Transverse mass spectra indicate significantly larger radial flow for the heavier systems. At midrapidity, an enhancement of - >/ + > and - >/ + > at low P T are best explained by final state Coulomb interaction with the residual charge of the fireball
Source spectral index of heavy cosmic ray nuclei
International Nuclear Information System (INIS)
Engelmann, J.J.; Ferrando, P.; Koch-Miramond, L.; Masse, P.; Soutoul, A.; Webber, W.R.
1985-08-01
From the energy spectra of the heavy nuclei observed by the French-Danish experiment on HEAO-3, we have derived the source spectra of the mostly primary nuclei (C, O, Ne, Mg, Si, Ca and Fe) in the framework of an energy dependent leaky box model (Engelmann et al. 1985). In the present paper we want to derive more accurate spectral indices by using better values of the escape length based on the latest cross section measurements (Webber 1984, Soutoul et al. this conference). Our aim is also to extend the analysis to lower energies down to 0.4 GeV/n (kinetic energy observed near earth), using data obtained by other groups. The only nuclei for which we have a good data base in a broad range of energies are O and Fe, so the present study is restricted to these two elements
Problem of α-clustering levels in heavy nuclei
International Nuclear Information System (INIS)
Kadmenskij, V.G.; Kadmenskij, S.G.; Kurgalin, S.D.; Furman, V.I.
1982-01-01
From the optical model analysis of elastic scattering and absorption cross sections of α-particles including the (n,α) reaction induced by resonance neutrons it may be concluded that the conception of black nucleus is valid for α-particles. It was shown that the magnitudes of α-particle surface spectroscopic factors did not exceed 10sup(-2) for all the known α-transitions both in spherical and deformed heavy nuclei accounting for the ambiguities of the optical model potential. The possibilities of extracting the α-particles form factors of low-lying nuclear states from α-transfer reaction data are considered. From all the data considered it is concluded that there is no evidence for the revealing of α-clustering levels in heavy nuclei. (author)
Heavy ion collisions and quark distribution in nuclei
International Nuclear Information System (INIS)
Liu Lian-sou; Pan Ji-cai; Peng Hung-an
1986-01-01
Heavy-ion collisions are studied by means of two-component Fokker--Planck equations on the assumption that there exist multiquark states in nuclei. Inclusive cross sections for the production of protons are calculated in heavy-ion collisions of C+C, Ne+NaF, and Ar+KCl at 800 MeV/A; Ne+Na at 400 MeV/A, 800 MeV/A, and 2100 MeV/A. Satisfactory agreement with the experimental data near 90 degrees c.m. is obtained. The production of deuterons in the collision of C+C at 800 MeV/A is also discussed
Atomic nuclei decay modes by spontaneous emission of heavy ions
International Nuclear Information System (INIS)
Poenaru, D.N.; Ivascu, M.; Sandulescu, A.
1984-01-01
The great majority of the known nuclei, including the so-called stable nuclides, are in fact metastable with respect to several modes of spontaneous superasymmetric splitting. If the lifetime against these processes is larger than 10 30 s, the phenomenon is not detectable with available experimental techniques, hence one can admit stability from the practical point of view. A model extended from the fission theory of alpha decay allows one to estimate the lifetimes and the branching ratios relatively to the alpha decay for these natural radioactivities. From a huge amount of systematical calculations it is concluded that the process should proceed with maximum intensity in the trans-lead nuclei, where the minimum lifetime is obtained for parent nuclei - heavy clusters leading to a magic ( 208 Pb) or almost daughter nucleus. More than 140 nuclides with atomic number smaller than 25 are possible candidates to be emitted from heavy nuclei, with half-life n the 10 10 -10 30 s range. The shell structure and pairing effects are clearly manifested in these new decay modes
Classically dynamical behaviour of single particle in heavy nuclei
International Nuclear Information System (INIS)
Gu Jianzhong; Zhuo Yizhong; Wu Xizhen
1998-01-01
A detailed analysis of the classically dynamical behaviour of a nucleon in heavy nuclei in terms of the TCSM (two-center shell model) is presented. Poincare section is a convenient and reliable criterion to judge the regularity (or chaoticity) of a classical system. The numerical calculations in this work are carried out for a nucleon in 238 U. The Poincare section map and the Poincare surface of section for different conditions are presented
Yrast-yrare interaction strength and bandcrossing frequency
International Nuclear Information System (INIS)
Wu, C.S.; Zeng, J.Y.
1991-01-01
Accurate particle-number-conserving calculation shows that in a single-j model the yrast-yrare interaction V is always strong and no periodic oscillation of V with the degree of shell filling is found, in contrast to the results obtained by the Hartree-Fock-Bogoliubov approximation. To understand the behavior of V and bandcrossing frequency ω c , the spin-alignment, seniority structure, configuration structure, and ''quasiparticle structure'' of the yrast and yrare bands are analyzed in detail. Calculation in a two-j model (high-j intruder orbits plus normal orbits of opposite parity) was also carried out to illustrate schematically that a weak yrast-yrare interaction may occur for certain single-particle level scheme. The coexistence of normal low-j orbits with high-j intruder orbits is indispensible for a sharp backbending observed in some realistic nuclei
Studies of Heavy-Ion Reactions and Transuranic Nuclei
Energy Technology Data Exchange (ETDEWEB)
Schroeder, W. Udo [Univ. of Rochester, NY (United States). Dept. of Chemistry. Dept. of Physics
2016-07-28
Studies of heavy-ion reactions and transuranic nuclei performed by the University of Rochester Nuclear Science Research Group have been successful in furthering experimental systematics and theoretical understanding of the behavior of nuclear systems excited to their limits of stability. The theoretical results explain specifically the “boiling” and “vaporization” of atomic nuclei, but are more generally applicable to isolated, quantal many-particle systems which, under thermal or mechanical stresses, all disintegrate by evaporation, via surface cluster emission, or via fission-like processes. Accompanying experimental investigations by the group have demonstrated several new types of dynamical instability of nuclei: In central, “head-on” collisions, target nuclei exhibit limited ability to stop energetic projectile nuclei and to dissipate the imparted linear momentum. Substantial matter overlap (“neck”) between projectile and target nuclei, which is observed at elevated collision energies, can be stretched considerably and break at several places simultaneously. These results provide new testing grounds for microscopic theory of the cohesion of nuclear matter. This property has remained elusive, even though the elementary nucleon-nucleon forces are well known since some time. Technical R&D has resulted in a detailed characterization of a novel plastic material, which can now be used in the design of sensitive diagnostic systems for various types of radio-activity. Innovative application of powerful laser systems has produced intense, controllable sources of exotic particle radioactivity for nuclear investigations. Several students have received their Ph.D. degree in experimental nuclear science for their work on basic nuclear research or R&D projects.
Studies of Heavy-Ion Reactions and Transuranic Nuclei
International Nuclear Information System (INIS)
Schroeder, W. Udo
2016-01-01
Studies of heavy-ion reactions and transuranic nuclei performed by the University of Rochester Nuclear Science Research Group have been successful in furthering experimental systematics and theoretical understanding of the behavior of nuclear systems excited to their limits of stability. The theoretical results explain specifically the ''boiling'' and ''vaporization'' of atomic nuclei, but are more generally applicable to isolated, quantal many-particle systems which, under thermal or mechanical stresses, all disintegrate by evaporation, via surface cluster emission, or via fission-like processes. Accompanying experimental investigations by the group have demonstrated several new types of dynamical instability of nuclei: In central, ''head-on'' collisions, target nuclei exhibit limited ability to stop energetic projectile nuclei and to dissipate the imparted linear momentum. Substantial matter overlap (''neck'') between projectile and target nuclei, which is observed at elevated collision energies, can be stretched considerably and break at several places simultaneously. These results provide new testing grounds for microscopic theory of the cohesion of nuclear matter. This property has remained elusive, even though the elementary nucleon-nucleon forces are well known since some time. Technical R&D has resulted in a detailed characterization of a novel plastic material, which can now be used in the design of sensitive diagnostic systems for various types of radio-activity. Innovative application of powerful laser systems has produced intense, controllable sources of exotic particle radioactivity for nuclear investigations. Several students have received their Ph.D. degree in experimental nuclear science for their work on basic nuclear research or R&D projects.
Photon strength in spherical and deformed heavy nuclei
International Nuclear Information System (INIS)
Grosse, E.; Junghans, A.; Birgersson, E.; Massarczyk, R.; Schramm, G.; Becvar, F.
2010-01-01
Information on the photon strength in heavy nuclei with mass A>150 will be given and compared to respective data. The photon strength function is a very important ingredient for statistical model calculations - especially when these are used to describe neutron capture. Several schemes for a transmutation of radioactive waste favor nuclear reactions with fast neutrons and these also influence the performance of various reactor types proposed to deliver nuclear energy together with only small quantities of such waste. Reactions with fast neutrons are far less studied as compared to those induced by thermal neutrons. As they are not easily accessible experimentally, reference is often made to calculations using the statistical model. Photon emission probabilities are needed as input to such calculations aiming for predictions on fission to capture ratios. From the favorable comparison of our parameterization to the experimental data for photon induced as well radiative capture processes in nuclei with various shapes and level densities we conclude what follows. First, the giant dipole resonance has very much the same properties in all heavy nuclei when their deformation is properly accounted for and its spreading width varies only smoothly with the resonance energies E k and not with the photon energy E γ . The radiative neutron capture results presented confirm strength data found in the literature. We also learn that our parameterization is at least a good approximation for photon energies below 4 MeV that dominate this process
Heavy ions as probes of nuclei far from stability
International Nuclear Information System (INIS)
Moltz, D.M.; Nitschke, J.M.; Wilmarth, P.A.; Toth, K.S.
1989-01-01
Nuclei located far from stability provide us with an opportunity for studying nuclear matter existing under unusual conditions. In these regions of instability, radioactive decay becomes the predominant technique by which one can obtain structure information. We have been involved in the investigation of nuclear properties of nuclei close to the proton drip line. In our explorations we have utilized heavy-ion fusion, followed by particle evaporation, to produce the extremely neutron-deficient nuclei of interest. In our studies, single-particle states near the 82-neutron shell, populated in the β decay of short-lived nuclides, have been examined and their excitation energies determined. Numerous new isotopes, isomers, and β-delayed-proton and α-particle emitters have been discovered. This contribution will discuss our particle-decay investigations. These decay modes provide us with a convenient means of discovering new isotopes whose identification opens the way for further, more extensive explorations. Also, particle-decay energies in many instances can be used to determine mass differences between parent and daughter ground states. Such measurements are therefore used to test mass formulae and to obtain estimates of masses for proton rich nuclei. 19 refs., 13 figs
Neutron skin studies of medium and heavy nuclei
Directory of Open Access Journals (Sweden)
Thiel M.
2014-06-01
Full Text Available The recent PREX experiment at JLab has demonstrated the sensitivity of parity violating electron scattering to the neutron density, meanwhile outlining its major experimental challenges. On the other side, intermediate energy photons are an ideal probe for studying the properties of strongly interacting matter from the nuclear scale down to the sub-nuclear components of the nucleus. Among others coherent pion photoproduction can provide information on the existence and nature of neutron skins in nuclei. The simultaneous combination of different techniques allows a systematic determination across the periodic table thus benchmarking modern calculation. Recently a systematic investigation of the latter method has been exploited at MAMI (Mainz. At MESA the same setup as in the measurement of the weak mixing angle can be used to determine the parity-violating asymmetry for polarized electrons scattered on heavy nuclei with a 1% resolution. Status and prospects of the projects are presented.
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
Scattering of mass-3 projectiles from heavy nuclei
International Nuclear Information System (INIS)
Mukhopadyay, S.; Srivastava, D.K.; Ganguly, N.K.
1976-01-01
The interaction between heavy ions is a subject of great interest. It is well known that α-particle scattering shows most of the features which are observed in heavy ion scattering. In as much as mass-3 system is intermediate between heavy and light particles it will be interesting to investigate the scattering of mass-3 projectiles to see if it is possible to extend it to study the heavy ion scattering. Indeed; it has been seen that the 'molecular type' potentials, with a soft repulsive core and a shallow attractive well used for heavy ion collisions can be used to fit the elastic scattering data of mass-3 projectiles also. In the first part of this paper, a description is given of how this potential is generated with a special emphasis on saturation and second order effect through a density dependent interaction between nucleon and mass-3 projectiles. In the second part it is shown that the asymmetry dependence observed in the potential describing the scattering of mass-3 particles from heavier nuclei actually originates from the isospin interaction, when triton and helion are treated as two members of an isospin doublet. (Auth.)
Manifestation of the structure of heavy nuclei in their alpha decays
Energy Technology Data Exchange (ETDEWEB)
Adamian, G. G., E-mail: adamian@theor.jinr.ru; Antonenko, N. V.; Bezbakh, A. N.; Malov, L. A. [Joint Institute for Nuclear Research (Russian Federation)
2016-11-15
Low-lying one- and two-quasiparticle states of heavy nuclei are predicted. Alpha-decay chains, including those that proceed through isomeric states, are examined on the basis of the predicted properties of superheavy nuclei.
Decay of Hot Nuclei at Low Spins Produced by Antiproton-Annihilation in Heavy Nuclei
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.
Simultaneous measurements of helium and heavy nuclei fluxes in cosmic rays over Fort Churchill
International Nuclear Information System (INIS)
Bhatia, V.S.; Paruthi, S.; Kainth, G.S.
1977-01-01
We have made simultaneous measurements of fluxes of He an heavy nuclei (Z< or =10) in primary cosmic rays at three levels of solar activity. These nuclei have been studied in three nuclear emulsion stacks exposed over Fort Churchill, Canada, in 1963, 1964, and 1967. We had earlier reported our results on the heavy nuclei at the Hobart conference (Bhatia et al., 1971). Experimental results based on 1514 He nuclei tracks that were measured in these three stacks are presented in this paper. The experimentally obtained He and heavy nuclei differential energy spectra have been compared with the theoretically calculated near-earth spectra
Classically dynamical behaviour of a nucleon in heavy nuclei
International Nuclear Information System (INIS)
Gu Jianzhong; Zhao Enguang; Zong Hongshi; Zhuo Yizhong; Wu Xizhen
1998-01-01
Within the framework of the two-center shell model the classically dynamical behaviour of a nucleon in heavy nuclei is investigated systematically with the change of nuclear shape parameters for the first time. It is found that as long as the nucleonic energy 0is appreciably higher than the height of the potential barrier there is a good quantum-classical correspondence of nucleonic regular (chaotic) motion. Thus, Bohigas, Giannoni and Schmit conjecture is confirmed once again. We find that the difference between the potential barrier for prolate nuclei and that for oblate ones is reponsible for the energy-dependence difference between the nucleonic chaotic dynamics for prolate nuclei and that for oblate ones. In addition, it is suggested that nuclear dissipation is shape-dependent, and strong nuclear dissipation can be expected for medium or large separations in the presence of a considerable neck deformation built on a pronounced octupole-like deformation, which provides us a dynamical understanding of nuclear shape dependence of nuclear dissipation. (orig.)
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
Microscopic description of the three major bands in transitional nuclei
International Nuclear Information System (INIS)
Pineda S, R.L.
1986-01-01
The author has extended the Coherent Phonon Model to the description of the three major bands in medium heavy transitional nuclei. The model assumes an axially symmetric deformed ground intrinsic state for the description of the low lying yrast levels of the ground band, while the excited bands are generated by intrinsic excitations of the ground band. Good angular momentum states are generated by the Peierls-Yoccoz angular momentum projection method
Nuclear data evaluation for medium and heavy nuclei
International Nuclear Information System (INIS)
Mizumoto, Motoharu
1988-01-01
Present status of nuclear data evaluation works for medium and heavy nuclei is described in this paper. These data are being prepared for JENDL-3 (Japanese Evaluated Nuclear Data Library-Version 3). At present, about a half of the data files, which are expected to be stored in the final library, has been brought into a temporary library called JENDL-3T. The remaining works and additional revisions are still needed to be made in order to finalize the data library as JENDL-3. Special emphases have been put on the high energy neutron data for which the previous JENDL-2 had some inadequacies, and gamma-ray production cross sections have been newly evaluated. Systematic and consistent evaluations have been intended for the new evaluations. (author)
Remarks on the fission barriers of super-heavy nuclei
Energy Technology Data Exchange (ETDEWEB)
Hofmann, S. [GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt (Germany); Goethe-Universitaet Frankfurt, Institut fuer Physik, Frankfurt (Germany); Heinz, S.; Mann, R.; Maurer, J.; Muenzenberg, G.; Barth, W.; Dahl, L.; Kindler, B.; Kojouharov, I.; Lang, R.; Lommel, B.; Runke, J.; Scheidenberger, C.; Tinschert, K. [GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt (Germany); Antalic, S. [Comenius University, Department of Nuclear Physics and Biophysics, Bratislava (Slovakia); Eberhardt, K.; Thoerle-Pospiech, P.; Trautmann, N. [Johannes Gutenberg-Universitaet Mainz, Mainz (Germany); Grzywacz, R. [Oak Ridge National Laboratory, Oak Ridge, TN (United States); University of Tennessee, Knoxville, TN (United States); Hamilton, J.H. [Vanderbilt University, Department of Physics and Astronomy, Nashville, TN (United States); Henderson, R.A.; Kenneally, J.M.; Moody, K.J.; Shaughnessy, D.A.; Stoyer, M.A. [Lawrence Livermore National Laboratory, Livermore, CA (United States); Miernik, K. [Oak Ridge National Laboratory, Oak Ridge, TN (United States); University of Warsaw, Warsaw (Poland); Miller, D. [University of Tennessee, Knoxville, TN (United States); Morita, K. [RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama (Japan); Nishio, K. [Japan Atomic Energy Agency, Tokai, Ibaraki (Japan); Popeko, A.G.; Yeremin, A.V. [Joint Institute for Nuclear Research, Dubna (Russian Federation); Roberto, J.B.; Rykaczewski, K.P. [Oak Ridge National Laboratory, Oak Ridge, TN (United States); Uusitalo, J. [University of Jyvaeskylae, Department of Physics, Jyvaeskylae (Finland)
2016-04-15
Shell-correction energies of super-heavy nuclei are approximated by using Q{sub α} values of measured decay chains. Five decay chains were analyzed, which start at the isotopes {sup 285}Fl, {sup 294}118, {sup 291}Lv, {sup 292}Lv and {sup 293}Lv. The data are compared with predictions of macroscopic-microscopic models. Fission barriers are estimated that can be used to eliminate uncertainties in partial fission half-lives and in calculations of evaporation-residue cross-sections. In that calculations, fission probability of the compound nucleus is a major factor contributing to the total cross-section. The data also provide constraints on the cross-sections of capture and quasi-fission in the entrance channel of the fusion reaction. Arguments are presented that fusion reactions for synthesis of isotopes of elements 118 and 120 may have higher cross-sections than assumed so far. (orig.)
Fission barriers of two odd-neutron heavy nuclei
International Nuclear Information System (INIS)
Koh, Meng-Hock; Bonneau, L.; Nhan Hao, T. V.; Duc, Dao Duy; Quentin, P.
2015-01-01
The fission barriers of two odd-neutron heavy odd nuclei,namely the 235 U and 239 Pu isotopes have been calculated within a self-consistent Hartree-Fock-plus-BCS approach with blocking. A Skyrme nucleon-nucleon effective interaction has been used together with a seniority force to describe pairing correlations. A full account of the genuine time-reversal symmetry breaking due to the presence of an unpaired nucleon has been incorporated at the mean field level. The SIII and SkM* parametrizations of the Skyrme interaction have been retained as well as for a part a newer parametrization, SLy5*. The seniority force parameters have been fitted to reproduce experimental odd-even mass differences in the actinide region. To assess the relevance of our calculated fission barrier distribution (as a function of the quantum numbers), we have studied the quality of our results with respect to the spectroscopy of band heads (for configurations deemed to be a pure single particle character) in the ground and fission isomeric states. Fission barriers of the considered odd nuclei have been compared with what is obtained for their even-even neighbouring isotopes (namely 234 U and 236 U, 238 Pu and 240 Pu respectively) to determine the so-called specialization energies. Various corrections and associated uncertainties have been discussed in order to compare our results with available data
Status and prospect of super-heavy nuclei research at IMP
International Nuclear Information System (INIS)
Xu Hushan; Sun Zhiyu; Zhan Wenlong; Zhou Xiaohong; Huang Wenxue; Zhang Hongbin; Gan Zaiguo; Li Junqing; Ma Xinwen; Qin Zhi; Xiao Guoqing; Guo Zhongyan; Li Zhihui; Zhang Yuhu; Jin Genming; Huang Tianheng; Hu Zhengguo; Zhang Xueheng; Zheng Chuan; Chinese Academy of Sciences, Beijing
2006-01-01
The history and the international status of the super-heavy nuclei synthesis are briefly described. The related research work carried out at the Institute of Modern Physics (IMP) has been reviewed. The prospect of the super-heavy nuclei research at IMP has been introduced. (authors)
Gross shell structure at high spin in heavy nuclei
International Nuclear Information System (INIS)
Deleplanque, Marie-Agnes; Frauendorf, Stefan; Pashkevich, Vitaly V.; Chu, S.Y.; Unzhakova, Anja
2003-01-01
Experimental nuclear moments of inertia at high spins along the yrast line have been determined systematically and found to differ from the rigid-body values. The difference is attributed to shell effect and these have been calculated microscopically. The data and quantal calculations are interpreted by means of the semiclassical Periodic Orbit Theory. From this new perspective, features in the moments of inertia as a function of neutron number and spin, as well as their relation to the shell energies can be understood. Gross shell effects persist up to the highest angular momenta observed
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
Towards a non empirical description of heavy nuclei
International Nuclear Information System (INIS)
Duguet, Thomas
2012-01-01
Since the defence of my Ph.D. thesis in September 2002, I have essentially devoted nine years of research activity to advancing the formal understanding and enhancing the predictive power of SR and MR EDF approaches to structure and reaction properties of medium-to-heavy mass nuclei. In the most recent years, I have engaged myself into developing innovative ab-initio many-body methods applicable to medium-mass open-shell nuclei. On the long term, my two main objectives are (i) to advancing many-body methods and the understanding of many-fermion systems in general and (ii) to reducing decisively the phenomenological character of methods applicable to systems made out of a few tens to a few hundreds of fermions by addressing the points raised in the above introduction. The present document does not aim at summarizing those ten years of research activity. Rather, I made the choice to report in some details on three selected topics that are somewhat representative of my overall contribution to the field. The first part (Sec. II) describes an in-depth re-analysis of the concept of single-nucleon shell structure in the context of many-fermion systems. The second part (Sec. III) summarizes recent advances towards a more rigorous formulation of the MR-EDF method and discusses the corresponding remaining difficulties as well as ways under current development to overcome them. The third part (Sec. IV) discusses the on-going quest towards a microscopic description of superfluidity in nuclei and reports on the first-ever ab-initio calculations of open-shell medium-mass nuclei based on Self-consistent Gorkov Green's function theory. Although representative, the three above topics only cover a fraction of my research activity since my Ph.D. thesis defence. Consequently several other studies I have been involved with are briefly summarized in apps. A-E. For completeness, my publication list is also provided as an appendix. Last but not least, it is essential to stress that many
Studies of heavy-ion reactions and transuranic nuclei
International Nuclear Information System (INIS)
Schroeder, W.U.
1993-08-01
This report contain papers on the following topics: The Cold-Fusion Saga; Decay Patterns of Dysprosium Nuclei Produced in 32 S + 118,124 Sn Fusion Reactions; Unexpected Features of Reactions Between Very Heavy Ions at Intermediate Bombarding Energies; Correlations Between Neutrons and Charged Products from the Dissipative Reaction 197 Au+ 208 Pb at E/A = 29 MeV; Dissipative Dynamics of Projectile-Like Fragment Production in the Reaction 209 Bi+ 136 Xe at E/A = 28.2 MeV; Dynamical Production of Intermediate-Mass Fragments in Peripheral 209 Bi+ 136 Xe Collisions at E lab /A = 28.2 MeV; The Rochester 960-Liter Neutron Multiplicity Meter; A Simple Pulse Processing Concept for a Low-Cost Pulse-Shape-Based Particle Identification; A One-Transistor Preamplifier for PMT Anode Signals; A Five-Channel Multistop TDC/Event Handler for the SuperBall Neutron Multiplicity Meter; Construction of the SuperBall -- a 16,000-Liter Neutron Detector for Calorimetric Studies of Intermediate-Energy Heavy-Ion Reactions; A Computer Code for Light Detection Efficiency Calculations for Photo-multipliers of a Neutron Detector; Evaluation of Gd-Loaded Liquid Scintillators for the SuperBall Neutron Calorimeter; and Measurement of the Interaction of Cosmic-Ray μ - with a Muon Telescope
Kinematic separation and mass analysis of heavy recoiling nuclei
International Nuclear Information System (INIS)
Oganesyan, Yu.Ts.; Eremin, A.V.; Belozerov, A.V.
2002-01-01
Within the past twelve years, the recoil separator VASSILISSA has been used for investigation of evaporation residues produced in heavy-ion induced complete-fusion reactions. In the course of the experimental work in the region of the elements with 92 ≤ Z ≤ 94, fourteen new isotopes have been identified by the parent-daughter correlations. The study of the decay properties and formation cross sections of the isotopes of elements 110, 112, and 114 was performed with the use of the high intensity 48 Ca beams; 232 Th, 238 U and 242 Pu targets were used in the experiments. At the beam energies corresponding to the calculated cross-section maxima of the 3n evaporation channels, the isotopes 277 110, 283 112, and 287 114 were produced and identified. For further experiments aimed at the synthesis of the superheavy element isotopes (Z ≥ 110) with the intensive 48 Ca extracted beams, the improvements in the ion optical system of the separator and of the focal plane detector system have been made. As a result, for heavy recoiling nuclei with masses A ∼ 250, the mass resolution of about 2.5 % was achieved with a good energy and position resolutions of the focal plane detectors
Energy Technology Data Exchange (ETDEWEB)
Podolyak, Zs.; Steer, S.J.; Pietri, S.; Regan, P.H.; Brandau, C.; Catford, W.N.; Cullen, I.J.; Gelletly, W.; Jones, G.A.; Liu, Z.; Walker, P.M. [University of Surrey, Department of Physics, Guildford (United Kingdom); Gorska, M.; Gerl, J.; Wollersheim, H.J.; Grawe, H.; Becker, F.; Geissel, H.; Kelic, A.; Kojouharov, I.; Kurz, N.; Montes, F.; Prokopowicz, W.; Saito, T.; Schaffner, H.; Tashenov, S.; Werner-Malento, E. [GSI, Darmstadt (Germany); Rudolph, D.; Hoischen, R. [Lund University, Department of Physics, Lund (Sweden); Garnsworthy, A.B. [University of Surrey, Department of Physics, Guildford (United Kingdom); Yale University, WNSL, New Haven, CT (United States); Maier, K.H. [Institute of Nuclear Physics, Krakow (Poland); University of the West of Scotland, Dept. of Physics, Paisley (United Kingdom); Bednarczyk, P.; Grebosz, J. [GSI, Darmstadt (Germany); Institute of Nuclear Physics, Krakow (Poland); Caceres, L. [GSI, Darmstadt (Germany); Universidad Autonoma de Madrid, Dept. de Fisica Teorica, Madrid (Spain); Doornenbal, P. [GSI, Darmstadt (Germany); Universitaet zu Koeln, IKP, Koeln (Germany); Heinz, A. [Yale University, WNSL, New Haven, CT (United States); Kurtukian-Nieto, T. [Universidad de Santiago de Compostela, Santiago de Campostela (Spain); Benzoni, G.; Wieland, O. [Universita degli Studi di Milano (Italy); INFN, Milano (Italy); Pfuetzner, M. [Warsaw University, IEP, Warsaw (Poland); Jungclaus, A. [Universidad Autonoma de Madrid, Dept. de Fisica Teorica, Madrid (Spain); Balabanski, D.L. [Bulgarian Academy of Sciences, INRNE, Sofia (Bulgaria); Brown, B.A. [Univ. of Surrey, Dept. of Physics, Guildford (United Kingdom); Michigan State Univ., NSCL, East Lansing, MI (United States); Bruce, A.M.; Lalkovski, S. [Univ. of Brighton, School of Environment and Technology, Brighton (United Kingdom); Dombradi, Zs. [Institute for Nuclear Research, Debrecen (Hungary); Estevez, M.E. [Instituto de Fisica Corpuscular, Valencia (Spain)] [and others
2009-12-15
Heavy neutron-rich nuclei have been populated through the relativistic fragmentation of a {sup 208}{sub 82} Pb beam at E/A = 1 GeV on a 2.5 g/cm{sup 2} thick Be target. The synthesised nuclei were selected and identified in-flight using the fragment separator at GSI. Approximately 300 ns after production, the selected nuclei were implanted in an {proportional_to}8 mm thick perspex stopper, positioned at the centre of the RISING {gamma} -ray detector spectrometer array. A previously unreported isomer with a half-life T{sub 1/2} = 163(5) ns has been observed in the N=126 closed-shell nucleus {sup 205}{sub 79} Au. Through {gamma}-ray singles and {gamma}-{gamma} coincidence analysis a level scheme was established. The comparison with a shell model calculation tentatively identifies the spin-parity of the excited states, including the isomer itself, which is found to be I{sup {pi}} = (19/2{sup +}). (orig.)
New high spin states and isomers in the {sup 208}Pb and {sup 207}Pb nuclei
Energy Technology Data Exchange (ETDEWEB)
Broda, R.; Wrzesinski, J.; Pawlat, T. [and others
1996-12-31
The two most prominent examples of the heavy doubly closed shell (DCS) nuclei, {sup 208}Pb and {sup 132}Sn, are not accessible by conventional heavy-ion fusion processes populating high-spin states. This experimental difficulty obscured for a long time the investigation of yrast high-spin states in both DCS and neighboring nuclei and consequently restricted the study of the shell model in its most attractive regions. Recent technical development of multidetector gamma arrays opened new ways to exploit more complex nuclear processes which populate the nuclei of interest with suitable yields for gamma spectroscopy and involve population of moderately high spin states. This new possibility extended the range of accessible spin values and is a promising way to reach new yrast states. Some of these states are expected to be of high configurational purity and can be a source of important shell model parameters which possibly can be used later to check the validity of the spherical shell model description at yet higher spin and higher excitation energy. The nuclei in the closest vicinity of {sup 132}Sn are produced in spontaneous fission and states with spin values up to I=14 can be reached in fission gamma spectroscopy studies with the presently achieved sensitivity of gamma arrays. New results on yrast states in the {sup 134}Te and {sup 135}I nuclei populated in fission of the {sup 248}Cm presented at this conference illustrate such application of the resolving power offered by modern gamma techniques.
International Nuclear Information System (INIS)
Levchenko, B.B.; Nikolaev, N.N.
1985-01-01
In the framework of the additive quark model of multiple production on nuclei we calculate the multiplicity distributions of secondary particles and the correlations between secondary particles in πA and pA interactions with heavy nuclei. We show that intranuclear cascades are responsible for up to 50% of the nuclear increase of the multiplicity of fast particles. We analyze the sensitivity of the multiplicities and their correlations to the choice of the quark-hadronization function. We show that with good accuracy the yield of relativistic secondary particles from heavy and intermediate nuclei depends only on the number N/sub p/ of protons knocked out of the nucleus, and not on the mass number of the nucleus (N/sub p/ scaling)
International Nuclear Information System (INIS)
Haddad, S.
2010-01-01
The influence of the isovector coupling channel on the central depression parameter and the central value of the charge density distribution in heavy spherical nuclei was studied. The isovector coupling channel leads to about 50% increase of the central depression parameter, and weakens the dependency of both central depression parameter and the central density on the asymmetry, impressively contributing to the semibubble form of the charge density distribution in heavy nuclei, and increasing the probability of larger nuclei with higher proton numbers and higher neutron-to-proton ratios stable. (author)
International Nuclear Information System (INIS)
Dashin, S.A.; Marennyy, A.M.; Gertsen, G.P.
1982-07-01
Charge and energy spectra of heavy charged particles were measured. Measurements were performed by a package of dielectric track detectors mounted behind the shield of 60-80 kg m to the minus second power thick. The charge of nuclei was determined from the complete track length. A group of 1915 tracks of nuclei with Z 6 in the energy range 100-450 MeV/nuclon were identified. The differential charge spectrum of nuclei with 6 Z 28 and the energy spectrum of nuclei of the iron group were built
Microscopic study of proton emission from heavy nuclei
International Nuclear Information System (INIS)
Sahu, B.B.; Patra, S.K.; Agarwalla, S.K.
2011-01-01
In recent years many theoretical calculations have been employed to explain the observed lifetimes of proton radioactivity and alpha decay processes in the region of proton rich nuclei. These data are very promising for the analysis of possible irregularities in the structure of these proton-rich nuclei. They are also of great interest in rapid proton capture processes. Some new results for proton radioactivity in this region of proton-rich nuclei have indicated that the proton emission mode is rather competitive with the alpha decay one. In the energy domain of radioactivity, proton can be considered as a point charge having highest probability of being present in the parent nucleus
Heavy ion interactions of deformed nuclei. Progress report, May 1, 1984-December 31, 1984
International Nuclear Information System (INIS)
Oberacker, V.E.
1984-11-01
This progress report describes the main topics that were investigated during the reporting period: (a) a new microscopic approach to the calculation of heavy ion interaction potentials; (b) the dynamical orientation of deformed heavy nuclei near the distance of closest approach; and (c) the theory of Coulomb fission (project finished in Sept.)
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.
Introduction to the study of collisions between heavy nuclei
International Nuclear Information System (INIS)
Bayman, B.F.
1980-01-01
Current investigations concerning the collisions of nuclei governed by small de Broglie wavelengths are reviewed. The wave packets localize nuclei in regions small compared to their diameters. Cross sections are examined for potential scattering, elastic scattering, quasi-molecular states, peripheral particle-transfer reactions, fusion, and deep inelastic collisions. Theories of fusion and deep inelastic collisions are summarized. This paper is in the nature of a review-tutorial. 45 references, 51 figures, 2 tables
Competition between pairing and quadrupole deformation in the yrast sequence of sup(150,152)Dy
International Nuclear Information System (INIS)
Aberg, S.
1984-05-01
The yrast spectra are investigated for the non-collective nuclei sup(150,152)Dy using the Nilsson-Strutinsky + blocked BCS model. The separate effects from the pairing force and the quadrupole force (deformation changes) are studied. It is found that the pairing force is most important in describing the yrast line up to Iproportional30, while the quadrupole force is most important for I> or approx.20. The calculated increase of the oblate deformation with increasing spin is explained as an antipairing effect when only valence nucleons are building the total spin and as a polarization effect when the core becomes excited. (orig.)
On peculiarities of the cascade γ decay of heavy nuclei
International Nuclear Information System (INIS)
Boneva, S.T.; Khitrov, V.A.; Popov, Yu.P.; Sukhovoj, A.M.; Vasil'eva, E.V.; Yazvitskij, Yu.S.
1987-01-01
Comparison of measured and calculated by statistical theory sums of two-quanta cascade intensities in compound-nuclei 163 ≤ A ≤ 183 points to the dependence of cascade intensity on the structure of initial and intermediate levels. The dependence of two-quanta cascade intensity sum on reduced neutron widths of compound states of even-even nuclei-targets of rare earth regions is detected. In 175 Yb and 179 Hf nuclei a considerable increase in the intensity of two-quanta cascades at the energy of their intermediate level in the range of the calculated position of one-quasiparticle states of the Saxon-Woods deformed potential is observed
Breakdown of NpNn scheme in very heavy nuclei
International Nuclear Information System (INIS)
Varshney, A.K.; Singh, M.; Kumar, Rajesh; Gupta, K.K.; Gupta, D.K.
2016-01-01
The proton neutron interaction has been considered the key ingredient in the development of configuration mixing, collectivity and ultimately deformation in atomic nuclei for over five decades. Phenomenologically, the correlation of the integrated valance p - n interaction with the onset of collectivity and deformation has been described in terms of NpNn scheme
Dynamic deformation theory of spherical and deformed light and heavy nuclei with A = 12-240
International Nuclear Information System (INIS)
Kumar, Krishna.
1979-01-01
Deformation dependent wave functions are calculated for different types of even-even nuclei (spherical, transitional, deformed; light, medium, heavy) without any fitting parameters. These wave functions are employed for the energies, B(E2)'s, quadrupole and magnetic moments of selected nuclei with A = 12-240 (with special emphasis on 56 Fe, 154 Gd), and for neutron cross sections of 148 Sm, 152 Sm
Charge-exchange resonances and restoration of Wigner’s supersymmetry in heavy and superheavy nuclei
Energy Technology Data Exchange (ETDEWEB)
Lutostansky, Yu. S., E-mail: lutostansky@yandex.ru; Tikhonov, V. N. [National Research Center Kurchatov Institute (Russian Federation)
2016-11-15
Various facets of the question of whether Wigner’s supersymmetry [SU(4) symmetry] may be restored in heavy and superheavy nuclei are analyzed on the basis of a comparison of the results of calculations with experimental data. The energy difference between the giant Gamow–Teller resonance and the analog resonance (the difference of E{sub G} and E{sub A}) according to calculations based on the theory of finite Fermi systems is presented for the case of 33 nuclei for which experimental data are available. The calculated difference ΔE{sub G–A} of E{sub G} and E{sub A} tends to zero in heavier nuclei, showing evidence of the restoration of Wigner’s SU(4) symmetry. Also, the isotopic dependence of the Coulomb energy difference between neighboring isobaric nuclei is analyzed within the SU(4) approach for more than 400 nuclei in the mass-number range of A = 5–244. The restoration of Wigner’s SU(4) symmetry in heavy nuclei is confirmed. It is shown that the restoration of SU(4) symmetry is compatible with the possible existence of the stability island in the region of superheavy nuclei.
Nucleosynthesis of neutron-rich heavy nuclei during explosive helium burning in massive stars
International Nuclear Information System (INIS)
Blake, J.B.; Woosley, S.E.; Weaver, T.A.; Schramm, D.N.
1981-01-01
The production of heavy nuclei during explosive helium burning has been calculated using a hydrodynamical model of a 15 M/sub sun/ (Type II) supernovae and a n-process nuclear reaction network. The resulting neutron-rich heavy nuclei are not produced in the relative abundances of solar-system r-process material, especially in the vicinity of Pt, nor are any actinides produced. These deficiencies reflect an inadequate supply of neutrons. However, some neutron-rich isotopes, normally associated with the r-process, are produced which may be significant for the production of isotopic anomalies in meteorites
Quantum electrodynamic effects for light and heavy nuclei
International Nuclear Information System (INIS)
Anon.
1973-01-01
The autoionization of positrons and the problem of vacuum polarization are discussed within the framework of quantum field theory. Various possible heavy ion experiments to check on the nonlinearity of electrodynamics are described. (8 figures) (U.S.)
Cluster aspects of alpha decay of heavy spherical nuclei
International Nuclear Information System (INIS)
Kadmenskij, S.G.; Furman, V.I.; Kholan, S.; Khlebostroev, V.G.
1975-01-01
On the basis of the non-R-Matrix approach to the α-decay theory the surface α-cluster model of α-decay is introduced. In the frame of this model evidence is obtained about an important contribution of the peripherical region of parent nuclei for the absolute α-decay widths. A classification of the α-transitions following the values of experimental probabilities for the existence of α-particles at the nuclear surface is performed
Spectroscopy of N approximately 82 nuclei near the proton drip line
International Nuclear Information System (INIS)
Daly, P.J.
1984-01-01
The yrast spectroscopy of Z>64 nuclei close to the proton drip line is discussed. This is a region of shell model nuclei in which high-spin excitations are accessible with heavy ion beams, and the occurrence of many isomers will facilitate future spectroscopic study of these nuclei to much higher spins that were observed in these investigations. The study of πhsub(11/2)sup(n) excitations in n=82 nuclei above 146 Gd provided particularly interesting results, since in certain respects their properties match shell model predictions better than those of jsup(n) states near traditional doubly magic nuclei. First results for N=81 nuclei above Z=64 were also reported, but much work remains to be done in the Z>64, N<82 quadrant
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
Collectivity in heavy nuclei in the shell model Monte Carlo approach
International Nuclear Information System (INIS)
Özen, C.; Alhassid, Y.; Nakada, H.
2014-01-01
The microscopic description of collectivity in heavy nuclei in the framework of the configuration-interaction shell model has been a major challenge. The size of the model space required for the description of heavy nuclei prohibits the use of conventional diagonalization methods. We have overcome this difficulty by using the shell model Monte Carlo (SMMC) method, which can treat model spaces that are many orders of magnitude larger than those that can be treated by conventional methods. We identify a thermal observable that can distinguish between vibrational and rotational collectivity and use it to describe the crossover from vibrational to rotational collectivity in families of even-even rare-earth isotopes. We calculate the state densities in these nuclei and find them to be in close agreement with experimental data. We also calculate the collective enhancement factors of the corresponding level densities and find that their decay with excitation energy is correlated with the pairing and shape phase transitions. (author)
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
Revision of heavy nuclei data in JENDL-3.2
Energy Technology Data Exchange (ETDEWEB)
Kawano, Toshihiko [Kyushu Univ., Advanced Energy Engineering Science, Kasuga, Fukuoka (Japan)
2000-03-01
In order to deal with problems concerning the data of heavy nuclides in JENDL-3.2, a working group was organized to update the evaluated nuclear data of Uranium, Plutonium, and Thorium isotopes. The current status of the working group is reviewed, and some results about resonance parameters, secondary neutron energy spectra, fission cross sections, and direct/semidirect capture process are shown. (author)
Revision of heavy nuclei data in JENDL-3.2
International Nuclear Information System (INIS)
Kawano, Toshihiko
2000-01-01
In order to deal with problems concerning the data of heavy nuclides in JENDL-3.2, a working group was organized to update the evaluated nuclear data of Uranium, Plutonium, and Thorium isotopes. The current status of the working group is reviewed, and some results about resonance parameters, secondary neutron energy spectra, fission cross sections, and direct/semidirect capture process are shown. (author)
Experimental study of synthesis of heavy nuclei at JAERI
International Nuclear Information System (INIS)
Nishio, K.; Ikezoe, H.; Mitsuoka, S.; Satou, K.
2001-01-01
Evaporation residue (ER) cross sections for 82 Se+ nat Ce and 76 Ge+ 150 Nd were measured in the vicinity of the Coulomb barrier, and the fusion probability was obtained with the aid of calculated survival probability. The former system represents fusion of two spherical nuclei, the latter fusion involving the pro-lately deformed target 150 Nd. The collision of 76 Ge with the side of 150 Nd is more compact in configuration at touching. The system 82 Se+ nat Ce showed fusion hindrance in form of extra-extra-push energy of 27 ± 5 MeV, whereas the system 76 Ge+ 150 Nd does not show fusion hindrance at and above the Coulomb barrier energy, suggesting that the reaction starting from the compact touching point results in a higher fusion probability. (author)
Decay of the giant monopole resonance in heavy nuclei
International Nuclear Information System (INIS)
Brandenburg, S.
1985-01-01
In this thesis an experimental study of the properties of the giant monopole resonance (GMR) in nuclei is described. The main subject is the study of the neutron decay of the GMR in 208 Pb, and the fission decay of the GMR in 238 U. Furthermore the strength distribution and decay properties of the monopole strength in 24 Mg and 40 Ca were studied. The strength distribution of the isoscalar monopole (and also of the isoscalar dipole) strength as obtained from the angular distribution of the excited strength at small scattering angles are discussed. For the excitation of the GMR inelastic scattering at very small scattering angles, including 0 0 , of 120 MeV α-particles was employed. The experimental technique for performing this type of measurements at the KVI was developed in the course of this study and is the subject of a separate chapter. (Auth.)
Energy Technology Data Exchange (ETDEWEB)
Furusawa, Shun; Yamada, Shoichi [Advanced Research Institute for Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555 (Japan); Sumiyoshi, Kohsuke [Numazu College of Technology, Ooka 3600, Numazu, Shizuoka 410-8501 (Japan); Suzuki, Hideyuki, E-mail: furusawa@heap.phys.waseda.ac.jp [Faculty of Science and Technology, Tokyo University of Science, Yamazaki 2641, Noda, Chiba 278-8510 (Japan)
2013-08-01
We construct new equations of state for baryons at subnuclear densities for the use in core-collapse simulations of massive stars. The abundance of various nuclei is obtained together with thermodynamic quantities. A model free energy is constructed, based on the relativistic mean field theory for nucleons and the mass formula for nuclei with the proton number up to {approx}1000. The formulation is an extension of the previous model, in which we adopted the liquid drop model to all nuclei under the nuclear statistical equilibrium. We reformulate the new liquid drop model so that the temperature dependences of bulk energies could be taken into account. Furthermore, we extend the region in the nuclear chart, in which shell effects are included, by using theoretical mass data in addition to experimental ones. We also adopt a quantum-theoretical mass evaluation of light nuclei, which incorporates the Pauli- and self-energy shifts that are not included in the ordinary liquid drop model. The pasta phases for heavy nuclei are taken into account in the same way as in the previous model. We find that the abundances of heavy nuclei are modified by the shell effects of nuclei and temperature dependence of bulk energies. These changes may have an important effect on the rates of electron captures and coherent neutrino scatterings on nuclei in supernova cores. The abundances of light nuclei are also modified by the new mass evaluation, which may affect the heating and cooling rates of supernova cores and shocked envelopes.
International Nuclear Information System (INIS)
Furusawa, Shun; Yamada, Shoichi; Sumiyoshi, Kohsuke; Suzuki, Hideyuki
2013-01-01
We construct new equations of state for baryons at subnuclear densities for the use in core-collapse simulations of massive stars. The abundance of various nuclei is obtained together with thermodynamic quantities. A model free energy is constructed, based on the relativistic mean field theory for nucleons and the mass formula for nuclei with the proton number up to ∼1000. The formulation is an extension of the previous model, in which we adopted the liquid drop model to all nuclei under the nuclear statistical equilibrium. We reformulate the new liquid drop model so that the temperature dependences of bulk energies could be taken into account. Furthermore, we extend the region in the nuclear chart, in which shell effects are included, by using theoretical mass data in addition to experimental ones. We also adopt a quantum-theoretical mass evaluation of light nuclei, which incorporates the Pauli- and self-energy shifts that are not included in the ordinary liquid drop model. The pasta phases for heavy nuclei are taken into account in the same way as in the previous model. We find that the abundances of heavy nuclei are modified by the shell effects of nuclei and temperature dependence of bulk energies. These changes may have an important effect on the rates of electron captures and coherent neutrino scatterings on nuclei in supernova cores. The abundances of light nuclei are also modified by the new mass evaluation, which may affect the heating and cooling rates of supernova cores and shocked envelopes
Furusawa, Shun; Sumiyoshi, Kohsuke; Yamada, Shoichi; Suzuki, Hideyuki
2013-08-01
We construct new equations of state for baryons at subnuclear densities for the use in core-collapse simulations of massive stars. The abundance of various nuclei is obtained together with thermodynamic quantities. A model free energy is constructed, based on the relativistic mean field theory for nucleons and the mass formula for nuclei with the proton number up to ~1000. The formulation is an extension of the previous model, in which we adopted the liquid drop model to all nuclei under the nuclear statistical equilibrium. We reformulate the new liquid drop model so that the temperature dependences of bulk energies could be taken into account. Furthermore, we extend the region in the nuclear chart, in which shell effects are included, by using theoretical mass data in addition to experimental ones. We also adopt a quantum-theoretical mass evaluation of light nuclei, which incorporates the Pauli- and self-energy shifts that are not included in the ordinary liquid drop model. The pasta phases for heavy nuclei are taken into account in the same way as in the previous model. We find that the abundances of heavy nuclei are modified by the shell effects of nuclei and temperature dependence of bulk energies. These changes may have an important effect on the rates of electron captures and coherent neutrino scatterings on nuclei in supernova cores. The abundances of light nuclei are also modified by the new mass evaluation, which may affect the heating and cooling rates of supernova cores and shocked envelopes.
Observation of heavy cluster emission from radioactive 230U nuclei
International Nuclear Information System (INIS)
Pan Qiangyan; Yuan Shuanggui; Yang Weifan; Li Zongwei; Ma Taotao; Guo Junsheng; Liu Mingyi; Liu Hongye; Xu Shuwei; Gan Zaiguo; Kong Dengming; Qiao Jimin; Luo Zihua; Zhang Mutian; Wang Shuhong
1999-01-01
230 Pa was produced with the reaction 232 Th (p, 3n) 230 Pa in the irradiation powder targets of ThO 2 with 35 MeV proton beam. Sources of 230 Pa→ 230 U + β - were prepared by radiochemical method. Using solid-state track registration detectors, two events of 230 U decay with heavy cluster emission have been observed. The preliminary branching ratio to α-decay comes out to be B = λ Ne /λ α = (1.3 ± 0.8) x 10 -14
Studies of heavy-ion reactions and transuranic nuclei
International Nuclear Information System (INIS)
Schroeder, W.U.; Huizenga, J.R.
1991-08-01
The development of the ''cold-fusion'' episode is reviewed. Ongoing studies of compound-nucleus formation and decay via the neutron multiplicity distribution confirm the validity of conventional statistical theory. The excitation energy partition in near-barrier damped 58 Ni + 208 Pb collisions is found to be largely independent of the direction of net mass transfer, supporting a diffusion-like nucleon-exchange mechanism. Exclusive experiments on the heavy reaction systems 197 Au + 208 Pb and 209 Bi + 136 Xe in the Fermi-energy domain have revealed important new insights into the reaction mechanism, which is found to be dominated by damped, binary processes. The effectiveness of the neutron multiplicity as an impact-parameter filter is demonstrated. It is shown that very-heavy-ion reactions lead to transient nuclear systems with temperatures in excess of τ = 6 MeV and transfer of large, aligned spins to reaction fragments. The first measurements of neutrons in coincidence with kinematically identified reaction fragments provide evidence for the binary, sequential character of dissipative collisions in the Fermi-energy domain. Also for the first time, a full event characterization was achieved for nuclear reactions in terms of neutrons and charged particles. Technical information on this experiment is provided. First results yield strong evidence for dominantly binary primary reaction dynamics of even highly dissipative 209 Bi + (28MeV/u) 136 Xe collisions, associated with several intermediate-mass fragments
Studies of the giant resonances in heavy nuclei
International Nuclear Information System (INIS)
Cataldi, M.I.C.
1986-01-01
Experimental measurements of the eletrodisintegration cross section in 181 Ta, 208 Pb and 209 Bi nuclei are made in the Linear Accelerator of the IFUSP-Brazil. The cross section is obtained by the direct counting of the emitted neutrons, in an electron excitation energy range between 8 to 22 MeV. The experimental data are analysed throught the virtual photon method, with the aim of obtaining the isoscalar and isovectorial electric quadrupole giant resonance (E2GR) intensities, as well as the magnetic dipole intensity. For each studied nucleus the results obtained for the E2GR, isoscalar and isovectorial, are compared with the photodisintegration cross section measured by the Saclay and Livermore laboratories. From this comparison, it is observed that the photodisintegration cross sections are compatibles with the existence of an isovector E2GR, located between 120 to 130 A -1/3 Mev and which exhaust around 100% of the Energy-Weighted Sum rules (EWSR). (L.C.) [pt
Two-neutron transfer reactions with heavy-deformed nuclei
International Nuclear Information System (INIS)
Price, C.; Landowne, S.; Esbensen, H.
1988-01-01
In a recent communication we pointed out that one can combine the macroscopic model for two-particle transfer reactions on deformed nuclei with the sudden limit approximation for rotational excitation, and thereby obtain a practical method for calculating transfer reactions leading to high-spin states. As an example, we presented results for the reaction 162 Dy( 58 Ni, 60 Ni) 160 Dy populating the ground-state rotational band up to the spin I = 14 + state. We have also tested the validity of the sudden limit for the inelastic excitation of high spin states and we have noted how the macroscopic model may be modified to allow for more microscopic nuclear structure effects in an application to diabolic pair-transfer processes. This paper describes our subsequent work in which we investigated the systematic features of pair-transfer reactions within the macroscopic model by using heavier projectiles to generate higher spins and by decomposing the cross sections according to the multipolarity of the transfer interaction. Particular attention is paid to characteristic structures in the angular distributions for the lower spin states and how they depend on the angular momentum carried by the transferred particles. 11 refs., 3 figs
Constrained-path quantum Monte Carlo approach for non-yrast states within the shell model
Energy Technology Data Exchange (ETDEWEB)
Bonnard, J. [INFN, Sezione di Padova, Padova (Italy); LPC Caen, ENSICAEN, Universite de Caen, CNRS/IN2P3, Caen (France); Juillet, O. [LPC Caen, ENSICAEN, Universite de Caen, CNRS/IN2P3, Caen (France)
2016-04-15
The present paper intends to present an extension of the constrained-path quantum Monte Carlo approach allowing to reconstruct non-yrast states in order to reach the complete spectroscopy of nuclei within the interacting shell model. As in the yrast case studied in a previous work, the formalism involves a variational symmetry-restored wave function assuming two central roles. First, it guides the underlying Brownian motion to improve the efficiency of the sampling. Second, it constrains the stochastic paths according to the phaseless approximation to control sign or phase problems that usually plague fermionic QMC simulations. Proof-of-principle results in the sd valence space are reported. They prove the ability of the scheme to offer remarkably accurate binding energies for both even- and odd-mass nuclei irrespective of the considered interaction. (orig.)
Sub-barrier quasifission in heavy element formation reactions with deformed actinide target nuclei
Hinde, D. J.; Jeung, D. Y.; Prasad, E.; Wakhle, A.; Dasgupta, M.; Evers, M.; Luong, D. H.; du Rietz, R.; Simenel, C.; Simpson, E. C.; Williams, E.
2018-02-01
Background: The formation of superheavy elements (SHEs) by fusion of two massive nuclei is severely inhibited by the competing quasifission process. Low excitation energies favor SHE survival against fusion-fission competition. In "cold" fusion with spherical target nuclei near 208Pb, SHE yields are largest at beam energies significantly below the average capture barrier. In "hot" fusion with statically deformed actinide nuclei, this is not the case. Here the elongated deformation-aligned configurations in sub-barrier capture reactions inhibits fusion (formation of a compact compound nucleus), instead favoring rapid reseparation through quasifission. Purpose: To determine the probabilities of fast and slow quasifission in reactions with prolate statically deformed actinide nuclei, through measurement and quantitative analysis of the dependence of quasifission characteristics at beam energies spanning the average capture barrier energy. Methods: The Australian National University Heavy Ion Accelerator Facility and CUBE fission spectrometer have been used to measure fission and quasifission mass and angle distributions for reactions with projectiles from C to S, bombarding Th and U target nuclei. Results: Mass-asymmetric quasifission occurring on a fast time scale, associated with collisions with the tips of the prolate actinide nuclei, shows a rapid increase in probability with increasing projectile charge, the transition being centered around projectile atomic number ZP=14 . For mass-symmetric fission events, deviations of angular anisotropies from expectations for fusion fission, indicating a component of slower quasifission, suggest a similar transition, but centered around ZP˜8 . Conclusions: Collisions with the tips of statically deformed prolate actinide nuclei show evidence for two distinct quasifission processes of different time scales. Their probabilities both increase rapidly with the projectile charge. The probability of fusion can be severely
Study of ^{14}C Cluster Decay Half-Lives of Heavy Deformed Nuclei
Shamami, S. Rahimi; Pahlavani, M. R.
2018-01-01
A theoretical model based on deformed Woods-Saxon, Coulomb and centrifugal terms are constructed to evaluate the half-lives for the cluster radioactivity of various super heavy nuclei. Deformation have been applied on all parts of their potential containing nuclear barrier for cluster decay. Also, both parent and daughter nuclei are considered to be deformed. The calculated results of ^{14}C cluster radioactivity half-lives are compared with available experimental data. A satisfactory agreement between theoretical and measured data is achieved. Also, obtained half-lives for each decay family is agreed with Geiger-Nuttall law.
Symmetry-dictated trucation: Solutions of the spherical shell model for heavy nuclei
International Nuclear Information System (INIS)
Guidry, M.W.
1992-01-01
Principles of dynamical symmetry are used to simplify the spherical shell model. The resulting symmetry-dictated truncation leads to dynamical symmetry solutions that are often in quantitative agreement with a variety of observables. Numerical calculations, including terms that break the dynamical symmetries, are shown that correspond to shell model calculations for heavy deformed nuclei. The effective residual interaction is simple, well-behaved, and can be determined from basic observables. With this approach, we intend to apply the shell model in systematic fashion to all nuclei. The implications for nuclear structure far from stability and for nuclear masses and other quantities of interest in astrophysics are discussed
Momentum distributions in nuclei measured with relativistic heavy ions
International Nuclear Information System (INIS)
Hiller, B.; Huefner, J.; Heidelberg Univ.
1982-01-01
In a peripheral reaction between relativistic heavy ions, where one nucleon is knocked out of the projektile, the momentum distribution of the remaining fragment reflects the momentum distribution of the knocked out nucleon. This has been proven in a previous paper. Here we study how the final-state interaction between the knocked out nucleon and the observed fragment influences the result: The real part of the optical potential which describes the final-state interaction shifts the experimental momentum distribution by a value [ksub(||)] of a few tens of MeV/c and the imaginary part reduces the cross sections by a factor 2 roughly. We also derive the cross section for a proton as target. (orig.)
Yrast bands and signature inversion in double odd 162,164Lu
International Nuclear Information System (INIS)
Cardona, M.A.; Hojman, D.; Kreiner, A.J.; Somacal, H.; Davidson, J.; Davidson, M.; Acuna, D. de; Napoli, D.R.; Rico, J.; Burch, R.; Bazzacco, D.; Lenzi, S.M.; Rossi Alvarez, C.; Blasi, N.; Lo Bianco, G.
1996-01-01
High spin rotational bands in 162 Lu and 164 Lu have been studied by means of the 139 La( 28 Si,5n) and 139 La( 29(30) Si,4(5)n) reactions respectively. For both nuclei the yrast sequence which is associated with the πh 11/2 x νi 13/2 configuration shows the signature inversion feature. (orig.)
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
Detection of heavy nuclei in the plastic track detector CR-39
International Nuclear Information System (INIS)
Fumuro, F.; Ihara, R.; Ohta, I.; Sato, Y.; Tezuka, I.; Tasaka, S.; Sugimoto, H.
1982-01-01
Relativistic cosmic ray nuclei were detected in an emulsion chamber composed of a pile of solid state track detectors (CR-39) and the emulsion plates. The 460 heavy nuclei were observed by scanning of emulsion and CR-39 plastic plates. The normalized track etch rate (Vsub(t)/Vsub(b))-1 for relativistic iron group was measured as 1.3+-0.05 and bulk etch rate Vsub(b) as 1.63+-0.08 μm/hour after 32 hours etch in 6.8 N NaOH at 70 0 C. The charge detection threshold was obtained to be Z=6 for β=1 with the dip angle larger than 75 degrees. The charge resolution was estimated to be Δ Z=0.7 for iron, and Δ Z=0.4 for magnesium and silicon nuclei
Systematical calculations on the ground state properties of heavy and superheavy nuclei
International Nuclear Information System (INIS)
Ren, Z.Z.; Center of Theoretical Nuclear Physics, Lanzhou; Mao, Y.C.; Zhi, Q.J.; Xu, C.; Dong, T.K.
2007-01-01
The synthesis of superheavy elements is now a hot topic in nuclear physics. Alpha-decay and spontaneous fission are two main decay modes in heavy and superheavy regions. Theoretical studies on alpha radioactivity and spontaneous fission can provide useful information for experiments. We investigate the alpha-decay and spontaneous fission of heavy and superheavy nuclei with different models. This includes the alpha-decay energies, alpha decay half-lives, and half-lives of spontaneous fission. The theoretical alpha-decay half-lives are in good agreement with experimental ones. The calculated half-lives of spontaneous fission are in reasonable agreement with present data. The properties of unknown nuclei are predicted. (author)
Search for magnetic dipole strength and giant spin-flip resonances in heavy nuclei
Energy Technology Data Exchange (ETDEWEB)
Horen, D. J. [Oak Ridge National Lab., TN (USA); Ikegami, H.; Muraoka, M. [eds.; Osaka Univ., Suita (Japan). Research Center for Nuclear Physics
1980-01-01
A description is given of the use of high resolution (n, n) scattering and the (p, n) reaction as tools to investigate highly excited states with emphasis on information pertaining to magnetic dipole strength and giant spin-flip resonances in heavy nuclei. It is shown how the ability to uniquely determine the spins and parities of resonances observed in neutron scattering has been instrumental to an understanding of the distribution of M1 strength in sup(207,208)Pb. Some recent results of (p, n) studies with intermediate energy protons are discussed. Energy systematics of the giant Gamow-Teller (GT) resonance as well as a new ..delta..l = 1, ..delta..S = 1 resonance with J sup(..pi..) = (1,2)/sup -/ are presented. It is shown how the (p, n) reaction might be useful to locate M1 strength in heavy nuclei.
Recent developments in high-spin calculations in atomic nuclei
International Nuclear Information System (INIS)
Szymanski, Z.
1980-01-01
A brief introduction to the recent achievements in the high-spin domain in nuclear physics is given. Results of the calculations in highly developed rotational bands in deformed nuclei, as well as the calculations in the structure of the yrast isomers are presented. The calculations fail in two aspects: local minima in the yrast line are not confirmed experimentally, the overall slope of the yrast line in 152 Dy is considerably overestimated. The calculations of the yrast line with new Woods-Saxon parameters are now in progress. The parameters are chosen to reproduce the large gap in the levels at proton number Z=64. (M.H.)
GALS – setup for production and study of heavy neutron rich nuclei
Directory of Open Access Journals (Sweden)
Zemlyanoy Sergey
2015-01-01
Full Text Available The present limits of the upper part of the nuclear map are very close to stability while the unexplored area of heavy neutron-rich nuclides along the neutron closed shell N = 126 below 208Pb is extremely important for nuclear astrophysics investigations and, in particular, for the understanding of the r-process of astrophysical nucleosynthesis. This area of the nuclear map can be reached neither in fusion–fission reactions nor in fragmentation processes widely used nowadays for the production of exotic nuclei. A new way was recently proposed for the production of these nuclei via low-energy multi-nucleon transfer reactions. The estimated yields of neutron-rich nuclei are found to be significantly high in such reactions and several tens of new nuclides can be produced, for example, in the near-barrier collision of 136Xe with 208Pb. A new setup is proposed to produce and study heavy neutron-rich nuclei located along the neutron closed shell N=126.
GALS – setup for production and study of heavy neutron rich nuclei
Zemlyanoy, Sergey; Kozulin, Eduard; Kudryavtsev, Yury; Fedosseev, Valentin; Bark, Robert; Janas, Zenon; Othman, Hosam
2015-01-01
The present limits of the upper part of the nuclear map are very close to stability while the unexplored area of heavy neutron-rich nuclides along the neutron closed shell N = 126 below ^208Pb is extremely important for nuclear astrophysics investigations and, in particular, for the understanding of the r-process of astrophysical nucleosynthesis. This area of the nuclear map can be reached neither in fusion-fission reactions nor in fragmentation processes widely used nowadays for the production of exotic nuclei. A new way was recently proposed for the production of these nuclei via low-energy multi-nucleon transfer reactions. The estimated yields of neutron-rich nuclei are found to be significantly high in such reactions and several tens of new nuclides can be produced, for example, in the near-barrier collision of ^136Xe with ^208Pb. A new setup is proposed to produce and study heavy neutron-rich nuclei located along the neutron closed shell N=126.
New semi-empirical formula for α-decay half-lives of the heavy and superheavy nuclei
Energy Technology Data Exchange (ETDEWEB)
Manjunatha, H.C. [Government College for Women, Department of Physics, Kolar, Karnataka (India); Sridhar, K.N. [Government First Grade College, Department of Physics, Kolar, Karnataka (India)
2017-07-15
We have succesfully formulated the semi-empirical formula for α-decay half-lives of heavy and superheavy nuclei for different isotopes of the wide atomic-number range 94 < Z < 136. We have considered 2627 isotopes of heavy and superheavy nuclei for the fitting. The value produced by the present formula is compared with that of experiments and other eleven models, i.e. ImSahu, Sahu, Royer10, VS2, UNIV2, SemFIS2, WKB. Sahu16, Densov, VSS and Royer formula. This formula is exclusively for heavy and superheavy nuclei. α-decay is one of the dominant decay mode of superheavy nucleus. By identifying the α-decay mode superheavy nuclei can be detected. This formula helps in predicting the α-decay chains of superheavy nuclei. (orig.)
Contributions to the theory of alpha disintegration of heavy and superheavy nuclei
International Nuclear Information System (INIS)
Tarnoveanu, G.I.
1977-01-01
Alpha disintegration of heavy and super-heavy spherical nuclei is studied. When the new calculation technique for alpha intensities dependent on the shell-model has been applied, a technique which allows the use of a more complex structure of the alpha particle, the detailed calculation of the alpha half-times is performed for both radioactive alpha nuclei in the lead area and for the super-heavy nuclei, by using the R matrix theory of alpha disintegration independent of the channel radius. The relative values of overlap integrals calculated by means of the intrinsic function for the Gauss and Moshinsky type alpha particle are presented, as well as a comparison between them and the experiment values for 8.6, 9.00 and 9.6 fm channel radii in the case of Po, Ra, Rn and Th isotopes. Original contributions to the alpha disintegration theory are represented by the generalization of the Taylor series method expressing the transformations to the centre of mass, and the relative distance from two particles to four particles in the same harmonic oscillator potential, and by the development of the R matrix theory for alpha disintegration independent of the channel radius in the case of complex structured alpha particles. (author)
Near-Barrier Fusion of Heavy Nuclei. Coupling of the Channels
Zagrebaev, V I
2003-01-01
The problem of quantum description of near-barrier fusion of heavy nuclei taking place under strong coupling of relative motion with rotation of deformed nuclei and with dynamic deformations of their surfaces is studied in the paper. A new effective method is proposed for numerical solution of a set of coupled Schrodinger equations with boundary conditions corresponding to a full absorption of the flux penetrated through the multi-dimensional Coulomb barrier. The method has no limitation on the number of coupled channels and allows one to calculate fusion cross-sections of very heavy nuclei used for synthesis of super-heavy elements. A combined analysis of the multi-dimensional potential energy surface relief and the multi-channel wave function in the vicinity of the Coulomb barrier gives a clear interpretation of near-barrier fusion dynamics. Comparison with experimental data and with semi-empirical model calculations is performed. The computing codes are allocated at the web-server http://nrv.jinr.ru/nrv/ w...
Nuclear structure and weak rates of heavy waiting point nuclei under rp-process conditions
Nabi, Jameel-Un; Böyükata, Mahmut
2017-01-01
The structure and the weak interaction mediated rates of the heavy waiting point (WP) nuclei 80Zr, 84Mo, 88Ru, 92Pd and 96Cd along N = Z line were studied within the interacting boson model-1 (IBM-1) and the proton-neutron quasi-particle random phase approximation (pn-QRPA). The energy levels of the N = Z WP nuclei were calculated by fitting the essential parameters of IBM-1 Hamiltonian and their geometric shapes were predicted by plotting potential energy surfaces (PESs). Half-lives, continuum electron capture rates, positron decay rates, electron capture cross sections of WP nuclei, energy rates of β-delayed protons and their emission probabilities were later calculated using the pn-QRPA. The calculated Gamow-Teller strength distributions were compared with previous calculation. We present positron decay and continuum electron capture rates on these WP nuclei under rp-process conditions using the same model. For the rp-process conditions, the calculated total weak rates are twice the Skyrme HF+BCS+QRPA rates for 80Zr. For remaining nuclei the two calculations compare well. The electron capture rates are significant and compete well with the corresponding positron decay rates under rp-process conditions. The finding of the present study supports that electron capture rates form an integral part of the weak rates under rp-process conditions and has an important role for the nuclear model calculations.
Energy Technology Data Exchange (ETDEWEB)
Herdade, S B [Sao Paulo Univ., SP (Brazil). Inst. de Fisica
1980-01-01
In this work, it is made a study of the giant resonance E2 isoscalar, in heavy nuclei. Fission probabilities for this resonance were determined by various authors, in different experiments, for {sup 238}U. (A.C.A.S.).
Population and particle decay of isobaric analog states in medium heavy nuclei
International Nuclear Information System (INIS)
Gales, S.
1980-05-01
The systematic features of proton stripping and neutron pick-up reactions to Isobaric Analog States in medium heavy nuclei are presented. The ( 3 He,d) reaction investigated at high incident energy is shown to selectively excite high-spin particle-analog states. Similarly the ( 3 He,α) reaction populates hole-analog states. The recent results related to such highly excited states in a wide range of nuclei ( 48 Ca to 208 Pb) are discussed in the framework of the DWBA theory of direct reactions with special emphasis on the treatment of unbound proton states or deeply-bound neutron hole states. The particle decay of Isobaric Analog States are investigated using the ( 3 He,d p) and ( 3 He, α p) sequential processes. The experimental method developed at Orsay (0 0 detection) for particle-particle angular correlations is presented. The advantage and the limits of such approach are illustrated by typical examples of particle decays: core-excited states, neutron particle-hole multiplets and the first observation of the proton emission of hole-analog levels. In conclusion new experimental approaches such as asymmetry measurements for analog states observed in transfer reactions or possible population of double analog states in heavy nuclei are discussed
The project of the mass separator of atomic nuclei produced in heavy ion induced reactions
Oganessian, Yu. Ts.; Shchepunov, V. A.; Dmitriev, S. N.; Itkis, M. G.; Gulbekyan, G. G.; Khabarov, M. V.; Bekhterev, V. V.; Bogomolov, S. L.; Efremov, A. A.; Pashenko, S. V.; Stepantsov, S. V.; Yeremin, A. V.; Yavor, M. I.; Kalimov, A. G.
2003-05-01
A new separator and mass analyzer, named MASHA (mass analyzer of super heavy atoms), has been designed at the Flerov Laboratory JINR Dubna to separate and measure masses of nuclei and molecules with precision better than 10 -3. The set up can work in the wide mass range from A≈20 to A≈500, its mass acceptance is as large as ±2.8%. In particular, it allows unambiguous mass identification of super heavy nuclei with a resolution better than 1 amu at the level of 300 amu. Synthesized in nuclear reactions nuclides are emitted from an ECR ion source at energy E=40 kV and charge state Q=+1. Then they pass the following steps of separation and analysis: the first section of rough separation, the second section of separation and mass analysis and the final section of separation with a 90° electrostatic deflector. In the focal plane of the device, a focal plane detector determines positions (masses) of studied nuclei. Ion optics of the analyzer, optimized up to the second order, is considered. Description of its elements and subsystems is given.
The project of the mass separator of atomic nuclei produced in heavy ion induced reactions
Oganessian, Yu T; Dmitriev, S N; Itkis, M G; Gulbekyan, G G; Khabarov, M V; Bekhterev, V V; Bogomolov, S L; Efremov, A A; Pashenko, S V; Stepantsov, S V; Yeremin, A V; Yavor, M I; Kalimov, A G
2003-01-01
A new separator and mass analyzer, named MASHA (mass analyzer of super heavy atoms), has been designed at the Flerov Laboratory JINR Dubna to separate and measure masses of nuclei and molecules with precision better than 10 sup - sup 3. The set up can work in the wide mass range from A approx 20 to A approx 500, its mass acceptance is as large as +-2.8%. In particular, it allows unambiguous mass identification of super heavy nuclei with a resolution better than 1 amu at the level of 300 amu. Synthesized in nuclear reactions nuclides are emitted from an ECR ion source at energy E=40 kV and charge state Q=+1. Then they pass the following steps of separation and analysis: the first section of rough separation, the second section of separation and mass analysis and the final section of separation with a 90 deg. electrostatic deflector. In the focal plane of the device, a focal plane detector determines positions (masses) of studied nuclei. Ion optics of the analyzer, optimized up to the second order, is considere...
The project of the mass separator of atomic nuclei produced in heavy ion induced reactions
International Nuclear Information System (INIS)
Oganessian, Yu.Ts.; Shchepunov, V.A.; Dmitriev, S.N.; Itkis, M.G.; Gulbekyan, G.G.; Khabarov, M.V.; Bekhterev, V.V.; Bogomolov, S.L.; Efremov, A.A.; Pashenko, S.V.; Stepantsov, S.V.; Yeremin, A.V.; Yavor, M.I.; Kalimov, A.G.
2003-01-01
A new separator and mass analyzer, named MASHA (mass analyzer of super heavy atoms), has been designed at the Flerov Laboratory JINR Dubna to separate and measure masses of nuclei and molecules with precision better than 10 -3 . The set up can work in the wide mass range from A∼20 to A∼500, its mass acceptance is as large as ±2.8%. In particular, it allows unambiguous mass identification of super heavy nuclei with a resolution better than 1 amu at the level of 300 amu. Synthesized in nuclear reactions nuclides are emitted from an ECR ion source at energy E=40 kV and charge state Q=+1. Then they pass the following steps of separation and analysis: the first section of rough separation, the second section of separation and mass analysis and the final section of separation with a 90 deg. electrostatic deflector. In the focal plane of the device, a focal plane detector determines positions (masses) of studied nuclei. Ion optics of the analyzer, optimized up to the second order, is considered. Description of its elements and subsystems is given
The project of the mass separator of atomic nuclei produced in heavy ion induced reactions
Energy Technology Data Exchange (ETDEWEB)
Oganessian, Yu.Ts.; Shchepunov, V.A. E-mail: shchepun@sunhe.jinr.rushchepun@cv.jinr.ru; Dmitriev, S.N.; Itkis, M.G.; Gulbekyan, G.G.; Khabarov, M.V.; Bekhterev, V.V.; Bogomolov, S.L.; Efremov, A.A.; Pashenko, S.V.; Stepantsov, S.V.; Yeremin, A.V.; Yavor, M.I.; Kalimov, A.G
2003-05-01
A new separator and mass analyzer, named MASHA (mass analyzer of super heavy atoms), has been designed at the Flerov Laboratory JINR Dubna to separate and measure masses of nuclei and molecules with precision better than 10{sup -3}. The set up can work in the wide mass range from A{approx}20 to A{approx}500, its mass acceptance is as large as {+-}2.8%. In particular, it allows unambiguous mass identification of super heavy nuclei with a resolution better than 1 amu at the level of 300 amu. Synthesized in nuclear reactions nuclides are emitted from an ECR ion source at energy E=40 kV and charge state Q=+1. Then they pass the following steps of separation and analysis: the first section of rough separation, the second section of separation and mass analysis and the final section of separation with a 90 deg. electrostatic deflector. In the focal plane of the device, a focal plane detector determines positions (masses) of studied nuclei. Ion optics of the analyzer, optimized up to the second order, is considered. Description of its elements and subsystems is given.
Poisson and Porter-Thomas fluctuations in off-yrast rotational transitions
International Nuclear Information System (INIS)
Matsuo, M.; Doessing, T.; Herskind, B.; Frauendorf, S.
1993-01-01
Fluctuations associated with stretched E2 transitions from high-spin levels in nuclei around 168 Yb are investigated by a cranked shell model extended to include residual two-body interactions. In the cranked mean-field model without residual interactions, it is found that gamma-ray energies behave like random variables and the energy spectra show Poisson fluctuation. With two-body residual interactions included, the discrete transition pattern with unmixed rotational bands is still valid up to around 600 keV above yrast, in good agreement with experiments. At higher excitation energy, a gradual onset of rotational damping emerges. At 1.8 MeV above yrast, complete damping is observed with GOE-type fluctuations for both energy levels and transition strengths (Porter-Thomas fluctuations). (orig.)
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
Photo-disintegration of heavy nuclei at the core of Cen A
Energy Technology Data Exchange (ETDEWEB)
Kundu, Esha [Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400005 (India); Gupta, Nayantara, E-mail: esha.kundu@gmail.com, E-mail: nayan@rri.res.in [Raman Research Institute, Sadashiva Nagar, Bangalore 560080 (India)
2014-04-01
Fermi LAT has detected gamma ray emissions from the core of Cen A. More recently, a new component in the gamma ray spectrum from the core has been reported in the energy range of 4 GeV to tens of GeV. We show that the new component and the HESS detected spectrum of gamma rays from the core at higher energy have possibly a common origin in photo-disintegration of heavy nuclei. Assuming the cosmic rays are mostly Fe nuclei inside the core and their spectrum has a low energy cut-off at 52 TeV in the wind frame moving with a Doppler factor 0.25 with respect to the observer on earth, the cosmic ray luminosity required to explain the observed gamma ray flux above 1 GeV is found to be 1.5 × 10{sup 43} erg/sec.
Formation of heavy compound nuclei, their survival and correlation with longtime-scale fission
International Nuclear Information System (INIS)
Karamyan, S.A.; Yakushev, A.B.
2006-01-01
Fusion of two massive nuclei with formation of super-heavy compound nucleus (CN) is driven by the potential energy gradient, as follows from the analysis of nuclear reaction cross-sections. The conservative energy of the system is deduced in simple approximation using regularized nuclear mass and interaction barrier values. Different reactions for the synthesis of Z c 110-118 nuclei are compared and the favourable conditions are found for fusion of the stable (W-Pt) isotopes with radioactive fission fragment projectiles, like 94 Kr or 100 Sr. Thus, the cold fusion method can be extended for a synthesis of elements with Z > 113. Survival of the evaporation residue is defined by the neutron-to-fission probability ratio and by the successful emission of gammas at the final step of the reaction. Numerical estimates are presented. Fixation of evaporation residue products must correlate with longtime-scale fission and available experimental results are discussed
Giardina, G.; Mandaglio, G.; Nasirov, A. K.; Anastasi, A.; Curciarello, F.; Fazio, G.
2018-02-01
Experimental and theoretical results of the PCN fusion probability of reactants in the entrance channel and the Wsur survival probability against fission at deexcitation of the compound nucleus formed in heavy-ion collisions are discussed. The theoretical results for a set of nuclear reactions leading to formation of compound nuclei (CNs) with the charge number Z = 102- 122 reveal a strong sensitivity of PCN to the characteristics of colliding nuclei in the entrance channel, dynamics of the reaction mechanism, and excitation energy of the system. We discuss the validity of assumptions and procedures for analysis of experimental data, and also the limits of validity of theoretical results obtained by the use of phenomenological models. The comparison of results obtained in many investigated reactions reveals serious limits of validity of the data analysis and calculation procedures.
Production of nuclei far from the beta stability line using intermediate-energy heavy ions
International Nuclear Information System (INIS)
Guerreau, D.
1986-05-01
The production of far unstable nuclei using heavy ion accelerators in the intermediate energy domain is reviewed. The various mechanisms responsible for the production of exotic species, mainly the projectile fragmentation and transfer reactions, are discussed, and the first experimental results presented. Results can be summarized as follows: existence of 4 new isotopes 22 C, 23 N, 29 Ne, 30 Ne; indication of bound character of 71 Ni, 72 Ni; clear evidence for bound character of 23 Si, 27 S, 31 Ar, 35 Ca; indications of bound character of 43 V, 46 Mn, 47 Mn, 48 Fe, 50 Co, 52 Co, 52 Ni, 55 Cu, 56 Cu
Transfer products from the reactions of heavy ions with heavy nuclei
International Nuclear Information System (INIS)
Thomas, K.E. III.
1979-11-01
Production of nuclides heavier than the target from 86 Kr- and 136 Xe-induced reactions with 181 Ta and 238 U was investigated. Attempts were made to produce new neutron-excess Np and Pu isotopes by the deep inelastic mechanism. No evidence was found for 242 Np or 247 Pu. Estimates were made for the production of 242 Np, 247 Pu, and 248 Am from heavy-ion reactions with uranium targets. Comparisons of reactions of 86 Kr and 136 Xe ions with thick 181 Ta targets and 86 Kr, 136 Xe and 238 U ions with thick 238 U targets indicate that the most probable products are not dependent on the projectile. The most probable products can be predicted by the equation Z - Z/sub target/ = 0.43 (A - A/sub target/) + 1.0. The major effect of the projectile is the magnitude of the production cross section of the heavy products. Based on these results, estimates are made of the most probable mass of element 114 produced from heavy-ion reactions with 248 Cm and 254 Es targets. These estimates give the mass number of element 114 as approx. 287 if produced in heavy-ion reactions with these very heavy targets. Excitation functions of gold and bismuth isotopes arising from 86 Kr- and 136 Xe-induced reactions with thin 181 Ta targets were measured. These results indicate that the shape and location (in Z and A above the target) of the isotopic distributions are not strongly dependent on the projectile incident energy. Also, the nuclidic cross sections are found to increase with an increase in projectile energy to a maximum at approximately 1.4 to 1.5 times the Coulomb barrier. Above this maximum, the nuclidic cross sections are found to decrease with an increase in projectile energy. This decrease in cross section is believed to be due to fission of the heavy products caused by high excitation energy and angular momentum. 111 references, 39 figures, 34 tables
Transfer reaction studies in the region of heavy and superheavy nuclei at SHIP
Energy Technology Data Exchange (ETDEWEB)
Heinz, S; Comas, V; Hofmann, S; Ackermann, D; Heredia, J; Hessberger, F P; Khuyagbaatar, J; Kindler, B; Lommel, B; Mann, R, E-mail: s.heinz@gsi.de [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, 64291 Darmstadt (Germany)
2011-02-01
We studied multi-nucleon transfer reactions in the region of heavy and superheavy nuclei. The goal was to investigate these reactions as possibility to create new superheavy neutron-rich isotopes, which cannot be produced in fusion reactions. The experiments have been performed at the velocity filter SHIP at GSI. At SHIP we can detect and identify the heavy, target-like, transfer products. Due to the low background at the focal plane detector and the isotope identification via radioactive decays, the setup allows to reach an upper cross-section limit of 10 pb/sr within one day of beamtime. We investigated the systems {sup 58,64}Ni + {sup 207}Pb and {sup 48}Ca + {sup 248}Cm at beam energies below and up to 20% above the Coulomb barrier. At all energies we observed a massive transfer of protons and neutrons, where transfer products with up to eight neutrons more than the target nucleus could be identified.
International Nuclear Information System (INIS)
Kuzminski, J.
1980-01-01
The collective processes in collision of heavy-ions with atomic nuclei are discussed. Measured data on the S+Ti collision at Esub(LAB)=105, 130 and 144 MeV have been analysed in terms of a ''fission-like'' processes which seem to be a special case of deep inelastic collisions whose total available kinetic energy is completely dissipated. Applying transport theory it was possible to introduce a ''clock'' for measuring the time scale of nuclear processes in collision of heavy-ions by measuring the FWHM of mass distribution of emitted reaction products. Experimental data on continuum gamma spectra from Cu+Au collision at Esub(LAB)=400 MeV are presented and the angular momentum dissipation in this reaction is discussed. (author)
Band crossing and signature splitting in odd mass fp shell nuclei
International Nuclear Information System (INIS)
Velazquez, Victor; Hirsch, Jorge G.; Sun, Yang
2001-01-01
Structure of two sets of mirror nuclei: 47 V- 47 Cr and 49 Cr- 49 Mn, as well as 49 V and 51 Mn, is studied using the projected shell model. Their yrast spectra are described as an interplay between the angular momentum projected states around the Fermi level which carry different intrinsic K-quantum numbers. The deviations from a regular rotational sequence are attributed to band crossing and signature splitting, which are usually discussed in heavy nuclear systems. Our results agree reasonably with experimental data, and are comparable with those from the full pf shell model calculations
Axial asymmetry of excited heavy nuclei as essential feature for the prediction of level densities
Energy Technology Data Exchange (ETDEWEB)
Grosse, Eckart [Institute of Nuclear and Particle Physics, Technische Universitaet Dresden (Germany); Junghans, Arnd R. [Institute of Radiation Physics, Helmholtz-Zentrum Dresden-Rossendorf (Germany); Massarczyk, Ralph [Los Alamos National Laboratory, New Mexico (United States)
2016-07-01
In previous studies a considerable improvement of predictions for neutron resonance spacings by a modified back-shifted Fermi-gas model (BSFM) was found. The modifications closely follow the basic principles for a gas of weakly bound Fermions as given in text books of statistical physics: (1) Phase transition at a temperature defined by theory, (2) pairing condensation independent of A, and (3) proportionality of entropy to temperature (and thus the level density parameter) fixed by the Fermi energy. For finite nuclei we add: (4) the back-shift energy is defined by shell correction and (5) the collective enhancement is enlarged by allowing the axial symmetry to be broken. Nearly no parameter fitting is needed to arrive at a good reproduction of level density information obtained by various methods for a number of nuclei in a wide range of A and E. To that end the modified BSFM is complemented by a constant temperature approximation below the phase transition point. The axial symmetry breaking (5), which is an evidently essential feature, will also be regarded with respect to other observables for heavy nuclei.
International Nuclear Information System (INIS)
EI-Nagdy, M.S.; Abdel-Waged, Kh; Abdel-Halim, S.M.; Khalil, E.I.
2000-01-01
The reaction cross sections for p, d, He, C, Mg and S beams with different chemical components of emulsion nuclei at 4.5 A GeV/c have been studied with high statistics, and were compared with the calculations according to Glauber model. The multiplicity distributions of shower produced particles from these interactions with light and heavy emulsion nuclei are analyzed in terms of the negative binomial and Poisson distribution laws
Alpha-cluster preformation factor within cluster-formation model for odd-A and odd-odd heavy nuclei
Saleh Ahmed, Saad M.
2017-06-01
The alpha-cluster probability that represents the preformation of alpha particle in alpha-decay nuclei was determined for high-intensity alpha-decay mode odd-A and odd-odd heavy nuclei, 82 CSR) and the hypothesised cluster-formation model (CFM) as in our previous work. Our previous successful determination of phenomenological values of alpha-cluster preformation factors for even-even nuclei motivated us to expand the work to cover other types of nuclei. The formation energy of interior alpha cluster needed to be derived for the different nuclear systems with considering the unpaired-nucleon effect. The results showed the phenomenological value of alpha preformation probability and reflected the unpaired nucleon effect and the magic and sub-magic effects in nuclei. These results and their analyses presented are very useful for future work concerning the calculation of the alpha decay constants and the progress of its theory.
International Nuclear Information System (INIS)
Sagajdak, R.N.
2008-01-01
The production of heavy nuclei from Rn to Th around the N = 126 neutron shell in complete fusion reactions of nuclei has been considered in a systematic way in the framework of the conventional barrier-passing fusion model coupled with the Standard Statistical Model (SSM). Available data on the excitation functions for fusion and production of evaporation residues obtained in very asymmetric combinations are described with these models rather well. In the interaction of massive projectiles with heavy target nuclei quasi-fission effects appear in the entrance reaction channel. The quantity of the fusion probability introduced empirically has been used to reproduce excitation functions with the same SSM parameters (fission barriers) as those obtained in the analysis of very asymmetric combinations. A lack of stabilization against fission around N = 126 for Th nuclei was earlier explained with a reduced collective contribution to the level density in spherical nuclei. However, the present analysis shows severe inhibition for fusion, i.e., the drop in production cross sections of Th nuclei in the vicinity of N = 126 is mainly caused by entrance channel effects. The macroscopic component of fission barriers for nuclei involved in a deexcitation cascade has been derived and compared with the theoretical model predictions and available data
Near-yrast spectroscopy of 164Yb and neighbouring nuclei
International Nuclear Information System (INIS)
Jonsson, S.; Roy, H. and others.
1983-03-01
High-spin states in 164 Yb have been populated in the 152 Sm( 16 0,4n) and 150 Sm( 18 0,4n) reactions. From studies of γ-γ coincidences, γ-ray angular distributions and conversion electron measurements the level scheme has been constructed. The g-band and the S-band have been established to spin and parity 22(sup)+ and 26(sup)+, respectively, and the rotational sequences (π,α)=(-,1) 1 , (-,0) 1 and (-,0) 2 to 23(sup)-, 24(sup)- and 18(sup)-, respectively. The sidebands in 162 , 164 Er and 164 , 166 Yb are discussed. Constructed two-quasineutron configurations and cranked shell model (CSM) calculations are compared with the experimental results in 164 Yb. Residual interactions between quasiparticles in 164 Yb are calculated. Crossing frequencies and the gain in alignment are summarized for the Yb isotopes and the main features are discussed. (author)
International Nuclear Information System (INIS)
Volkov, V.V.; Cherepanov, E.A.; Kalandarov, Sh.A.
2016-01-01
A new approach to the interpretation of the process of spontaneous fission of heavy nuclei is suggested. It is based on nuclear physics data which are obtained in heavy ion collisions. The process of spontaneous fission consists of three sequential stages: clusterization of the valent nucleons of a heavy nucleus into a light nucleus-cluster, which leads to the formation of a dinuclear system; evolution of the dinuclear system which proceeds by nucleon transfer from the heavy to light nucleus; and decay of the dinuclear system from the equilibrium configuration into two fragments. [ru
Decay out of the yrast superdeformed band in 191Hg
International Nuclear Information System (INIS)
Sien, S.; Reiter, P.; Khoo, T.; Lauritsen, T.; Carpenter, M. P.; Ahmad, I.; Amro, H.; Calderin, I.; Dossing, T.; Fischer, S. M.; Garg, U.; Gassmann, D.; Hackman, G.; Hannachi, F.; Janssens, R. V. F.; Kharraja, B.; Korichi, A.; Lopez-Martens, A.; Moore, E. F.; Nisius, D.; Schuck, C.
1999-01-01
The excitation energies and spins of the yrast superdeformed band in 191 Hg have been determined by analyzing the quasicontinuum spectrum connecting the superdeformed and normal-deformed states. The results from this analysis, combined with that given by one-step decay lines, give confident assignments of the spins and energies of the yrast superdeformed band in 191 Hg
Study of the structure of yrast bands of neutron-rich 114-124Pd isotopes
Chaudhary, Ritu; Devi, Rani; Khosa, S. K.
2018-02-01
The projected shell model calculations have been carried out in the neutron-rich 114-124Pd isotopic mass chain. The results have been obtained for the deformation systematics of E(2+1) and E(4+1)/E({2}+1) values, BCS subshell occupation numbers, yrast spectra, backbending phenomena, B( E2) transition probabilities and g-factors in these nuclei. The observed systematics of E(2+1) values and R_{42} ratios in the 114-124Pd isotopic mass chain indicate that there is a decrease of collectivity as the neutron number increases from 68 to 78. The occurrence of backbending in these nuclei as well as the changes in the calculated B( E2) transition probabilities and g -factors predict that there are changes in the structure of yrast bands in these nuclei. These changes occur at the spin where there is crossing of g-band by 2-qp bands. The predicted backbendings and predicted values of B( E2)s and g-factors in some of the isotopes need to be confirmed experimentally.
International Nuclear Information System (INIS)
Kotov, Alexander; Chtchetkovski, Alexander; Fedorov, Oleg; Gavrikov, Yuri; Chestnov, Yuri; Poliakov, Vladimir; Vaishnene, Larissa; Vovchenko, Vil; Fukahori, Tokio
2003-01-01
The purpose of this work is experimental studies of the energy dependence of the fission cross sections of heavy nuclei, nat Pb, 209 Bi, 232 Th, 233 U, 235 U, 238 U, 237 Np and 239 Pu, by protons at the energies from 200 to 1000 MeV. At present experiment the method based on use of the gas parallel plate avalanche counters (PPACs) for registration of complementary fission fragments in coincidence and the telescope of scintillation counters for direct counting of the incident protons on the target has been used. First preliminary results of the energy dependences of proton induced fission cross sections for nat Pb, 209 Bi, 235 U and 238 U are reported. (author)
Density slope of the nuclear symmetry energy from the neutron skin thickness of heavy nuclei
International Nuclear Information System (INIS)
Chen Liewen; Ko Che Ming; Xu Jun; Li Baoan
2010-01-01
Expressing explicitly the parameters of the standard Skyrme interaction in terms of the macroscopic properties of asymmetric nuclear matter, we show in the Skyrme-Hartree-Fock approach that unambiguous correlations exist between observables of finite nuclei and nuclear matter properties. We find that existing data on neutron skin thickness Δr np of Sn isotopes give an important constraint on the symmetry energy E sym (ρ 0 ) and its density slope L at saturation density ρ 0 . Combining these constraints with those from recent analyses of isospin diffusion and the double neutron/proton ratio in heavy-ion collisions at intermediate energies leads to a more stringent limit on L approximately independent of E sym (ρ 0 ). The implication of these new constraints on the Δr np of 208 Pb as well as the core-crust transition density and pressure in neutron stars is discussed.
Breaking of axial symmetry in excited heavy nuclei as identified in giant dipole resonance data
Energy Technology Data Exchange (ETDEWEB)
Grosse, E.; Massarczyk, R. [Technische Universitaet Dresden, Institute of Nuclear and Particle Physics, Dresden (Germany); Junghans, A.R. [Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiation Physics, Dresden (Germany)
2017-11-15
A recent theoretical prediction of a breaking of axial symmetry in quasi all heavy nuclei is confronted to a new critical analysis of photon strength functions of nuclei in the valley of stability. For the photon strength in the isovector giant dipole resonance (IVGDR) regime a parameterization of GDR shapes by the sum of three Lorentzians (TLO) is extrapolated to energies below and above the IVGDR. The impact of non-GDR modes adding to the low energy slope of photon strength is discussed including recent data on photon scattering and other radiative processes. These are shown to be concentrated in energy regions where various model calculations predict intermediate collective strength; thus they are obviously separate from the IVGDR tail. The triple Lorentzian (TLO) ansatz for giant dipole resonances is normalized in accordance to the dipole sum rule. The nuclear droplet model with surface dissipation accounts well for positions and widths without local, nuclide specific, parameters. Very few and only global parameters are needed when a breaking of axial symmetry already in the valley of stability is admitted and hence a reliable prediction for electric dipole strength functions also outside of it is expected. (orig.)
Application of the interacting boson model to collective states in medium heavy nuclei
International Nuclear Information System (INIS)
Kaup, U.
1983-01-01
In the framework of the interacting boson model a systematic description of even-even isotopes of the medium heavy elements selenium, krypton, and strontium is given. The number of the free parameters could be kept very small by the determination of the physically relevant terms of the general model Hamiltonian. The variation of the collectivity from spherical to deformed, γ-soft nuclei could be mainly derived from the influence of the number of valence nucleons. All model parameters vary smoothly as function of the valence particle number and in qualitative agreement with predictions of a simplified microscopical model. Odd nuclei were studied in the framework of the interacting boson-fermion model. Beside the phenomenological description of odd-even rubidium, technetium, and silver isotope this part of the thesis is occupied mainly by the microscopical theory of the boson-fermion model. The effect of the antisymmetrization of the last, odd particle with the core nucleons is discussed. The microscopic theory is supplemented by the derivation of the so called Pauli term from the interaction of identical nucleons. (orig./HSI) [de
Review of even element super-heavy nuclei and search for element 120
Energy Technology Data Exchange (ETDEWEB)
Hofmann, S. [GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt (Germany); Goethe-Universitaet Frankfurt, Institut fuer Physik, Frankfurt (Germany); Heinz, S.; Mann, R.; Maurer, J.; Barth, W.; Burkhard, H.G.; Dahl, L.; Kindler, B.; Kojouharov, I.; Lang, R.; Lommel, B.; Runke, J.; Scheidenberger, C.; Schoett, H.J.; Tinschert, K. [GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt (Germany); Muenzenberg, G. [GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt (Germany); Manipal University, Manipal Centre for Natural Sciences, Manipal, Karnataka (India); Antalic, S.; Saro, S. [Comenius University, Department of Nuclear Physics and Biophysics, Bratislava (Slovakia); Eberhardt, K.; Thoerle-Pospiech, P.; Trautmann, N. [Johannes Gutenberg-Universitaet Mainz, Mainz (Germany); Grzywacz, R. [Oak Ridge National Laboratory, Oak Ridge, TN (United States); University of Tennessee, Knoxville, TN (United States); Hamilton, J.H. [Vanderbuilt University, Department of Physics and Astronomy, Nashville, TN (United States); Henderson, R.A.; Kenneally, J.M.; Moody, K.J.; Shaughnessy, D.A.; Stoyer, M.A. [Lawrence Livermore National Laboratory, Livermore, CA (United States); Miernik, K. [Oak Ridge National Laboratory, Oak Ridge, TN (United States); University of Warsaw, Warsaw (Poland); Miller, D. [University of Tennessee, Knoxville, TN (United States); Morita, K. [RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama (Japan); Nishio, K. [Japan Atomic Energy Agency, Tokai, Ibaraki (Japan); Popeko, A.G.; Yeremin, A.V. [Joint Institute for Nuclear Research, Dubna (Russian Federation); Roberto, J.B.; Rykaczewski, K.P. [Oak Ridge National Laboratory, Oak Ridge, TN (United States); Uusitalo, J. [University of Jyvaeskylae, Department of Physics, Jyvaeskylae (Finland)
2016-06-15
The reaction {sup 54}Cr + {sup 248}Cm was investigated at the velocity filter SHIP at GSI, Darmstadt, with the intention to study production and decay properties of isotopes of element 120. Three correlated signals were measured, which occurred within a period of 279ms. The heights of the signals correspond with the expectations for a decay sequence starting with an isotope of element 120. However, a complete decay chain cannot be established, since a signal from the implantation of the evaporation residue cannot be identified unambiguously. Measured properties of the event chain are discussed in detail. The result is compared with theoretical predictions. Previously measured decay properties of even element super-heavy nuclei were compiled in order to find arguments for an assignment from the systematics of experimental data. In the course of this review, a few tentatively assigned data could be corrected. New interpretations are given for results which could not be assigned definitely in previous studies. The discussion revealed that the cross-section for production of element 120 could be high enough so that a successful experiment seems possible with presently available techniques. However, a continuation of the experiment at SHIP for a necessary confirmation of the results obtained in a relatively short irradiation of five weeks is not possible at GSI presently. Therefore, we decided to publish the results of the measurement and of the review as they exist now. In the summary and outlook section we also present concepts for the continuation of research in the field of super-heavy nuclei. (orig.)
Probing QCD critical fluctuations from light nuclei production in relativistic heavy-ion collisions
Directory of Open Access Journals (Sweden)
Kai-Jia Sun
2017-11-01
Full Text Available Based on the coalescence model for light nuclei production, we show that the yield ratio Op-d-t=NH3Np/Nd2 of p, d, and 3H in heavy-ion collisions is sensitive to the neutron relative density fluctuation Δn=〈(δn2〉/〈n〉2 at kinetic freeze-out. From recent experimental data in central Pb+Pb collisions at sNN=6.3 GeV, 7.6 GeV, 8.8 GeV, 12.3 GeV and 17.3 GeV measured by the NA49 Collaboration at the CERN Super Proton Synchrotron (SPS, we find a possible non-monotonic behavior of Δn as a function of the collision energy with a peak at sNN=8.8 GeV, indicating that the density fluctuations become the largest in collisions at this energy. With the known chemical freeze-out conditions determined from the statistical model fit to experimental data, we obtain a chemical freeze-out temperature of ∼144 MeV and baryon chemical potential of ∼385 MeV at this collision energy, which are close to the critical endpoint in the QCD phase diagram predicted by various theoretical studies. Our results thus suggest the potential usefulness of the yield ratio of light nuclei in relativistic heavy-ion collisions as a direct probe of the large density fluctuations associated with the QCD critical phenomena.
Energy Technology Data Exchange (ETDEWEB)
Khalfallah, F
2007-08-15
Within the recent years, the spectroscopic study of single particle orbitals of very heavy elements (VHE) has become possible with the development of increasingly efficient experimental setups. This allows us, through nuclear deformation, to access with these deformed nuclei to orbitals situated around the Fermi level in the spherical superheavy elements (SHE) and learn more about the nuclear structure of these nuclei. The aim of this work is the spectroscopic studies of heavy and very heavy elements. Because of the experimental difficulties associated with the fusion reactions in the VHE region, a detailed optimization studies is essential. Simulation of energy loss and angular straggling of these nuclei due to the interaction in the target and to neutron's evaporation was carried out and allowed us to optimize the angular acceptance of the separators according to the target thickness. An extensive survey and exploration in the VHE region was also conducted on the basis of cross section's systematics in the literature and simulations carried out using the statistical code Hivap. In this framework, the possible extension of the range of validity of a set of Hivap parameters was investigated. This work has enabled us to prepare a list of experiments of interest for the production of very heavy nuclei. In this thesis, our work was concentrated on the spectroscopy of the nuclei No{sup 256} et Rf{sup 256} for which two experimental proposals were accepted. The octupole deformations predicted in the actinides region is studied in another part of this thesis, a part witch is dedicated to the gamma spectroscopy of Pa{sup 223}. The data from a new experiment carried out using the Jurogam-Ritu-Great setup are analysed and compared to previous results. They confirm the octupole deformed shape in this nucleus. (author)
2002-01-01
The aim of this experiment is twofold:\\\\ \\\\ Firstly to test the possibilities of collection of the heavy recoil nuclei with the device presented schematically on the figure. The recoil nuclei escaping from the irradiated target are first thermalised in a gas (N^2). One then takes advantage of their remaining charge to collect them with an electric field on the surface of a solid state detector. Tests already performed with other beams give absolute efficiency around 5\\%. The best conditions of collections with very energetic |1|2C have first to be tested. Secondly to get some insight into nuclear reaction mechanisms induced by 86~MeV/a.m.u. |1|2C using the possibilities of this recoil chamber. Two kinds of mechanisms should occur in these interactions. If the incident energy is damped (deep inelastic reaction, fusion), the heavy nucleus will be highly excited and the residual nuclei will lie along the @G^n/@G^p~=~1~line. For heavy nuclei this line is located at about 25~mass units from the stability line. If ...
International Nuclear Information System (INIS)
Oberacker, V.E.
1985-09-01
This Progress Report describes the main topics that were investigated during the reporting period: (1) a new microscopic approach (many-body theory with two-center shell model basis) to the calculation of heavy-ion interaction potentials, primarily for heavy systems; (2) dynamic alignment of deformed nuclei during heavy-ion collisions; (3) the role of shell effects, static deformation and dynamic alignment in heavy-ion fusion reactions; (4) giant nuclear quasimolecules and the positron problem. The proposed research has direct relevance to experimental programs supported by DOE, e.g. the Holifield Heavy-Ion Research Facility (HHIRF) at Oak Ridge, the ATLAS accelerator at Argonne National Laboratory, the Double MP Tandem at Brookhaven and some of the smaller University-based accelerators. A discussion of a review article on Coulomb fission is presented. 36 refs., 7 figs
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
International Nuclear Information System (INIS)
Sagaidak, R. N.
2009-01-01
Nuclear fission is well suited to study the dynamic properties and dissipative processes in cold and moderately excited nuclei. It is also a unique tool to explore level density and shell effects at an extreme deformation. Despite the significant progress in the fission studies, the isospin dependence of fission properties and, in particular, of fission barrier heights still remains an open problem. Theoretical fission model parameters are tuned by using the experimental nuclear and fission data close to stability [1]. The models provide a reasonable description of the fission barriers close to the stability line. However, large deviations are observed between predictions of different models for the fission barriers of very neutron-deficient and neutron-rich nuclei. These discrepancies (by as much as 20-30 MeV, see, e.g. [2]) become especially important in the r-process calculations for extremely neutron-rich nuclei, whose fission barriers determine the termination of the r-process by fission [3]. Unfortunately, such neutron-rich nuclei will probably not become accessible in the nearest experiments. Therefore, fission properties of exotic nuclei and especially their isospin dependence can be investigated in alternative regions of the Nuclide Chart, which are accessible for such studies now. Fusion-evaporation cross sections for heavy fissile nuclei obtained in heavy ion induced reactions as well as their fission cross sections are mainly determined by statistical properties of decaying compound nuclei (CN) and first of all by the fission-barrier heights of nuclei involved in the de-excitation chains leading to observable evaporation residues (ER). At the same time, the ER production and fission in nearly symmetric projectile-target fusion reactions leading to the most neutron-deficient CN could be strongly suppressed due to the quasi-fission (QF) effect [4], as observed recently in the 4 8C a induced reactions leading to Ra [5] and Pb [6] CN. The production of
High spin states and Yrast isomers in 211Rn
International Nuclear Information System (INIS)
Poletti, A.R.; Dracoulis, G.D.; Fahlander, C.; Morrison, I.
1981-01-01
Excited states in 211 Rn with spins up to 53/2 have been identified using (HI,xn) reactions and γ-ray techniques. A shell model calculation can reproduce the ordering of the yrast sequence up to spin 41/2 - . Several yrast isomers have been identified. Enhanced E3 transitions are observed and their systematic occurrence in this region discussed. The influence of the neutron hole, and possible core excitations on the effective moment of inertia are also pointed out
High spin states and yrast isomers in 211Rn
International Nuclear Information System (INIS)
Poletti, A.R.; Dracoulis, G.D.; Fahlander, C.; Morrison, I.
1980-12-01
Excited states in 211 Rn with spins up to 53/2 have been identified using (HI,xn) reactions and γ-ray techniques. A shell model calculation can reproduce the ordering of the yrast sequence up to spin 41/2. Several yrast isomers have been identified. Enhanced E3 transitions are observed and their systematic occurrence in this region discussed. The influence of the neutron hole, and possible core excitations on the effective moment of inertia are also pointed out
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.)
The SU(3) structure of rotational states in heavy deformed nuclei
International Nuclear Information System (INIS)
Jarrio, M.; Wood, J.L.; Rowe, D.J.
1991-01-01
The SU(3) coupling scheme provides an informative basis for the expansion of shell-model wave functions and their interpretation in collective-model terms. We show in this paper that it is possible, using the coupled-rotor-vibrator model, to infer averages of the distributions of SU(3) representation labels in heavy rotational nuclei by direct interpretation of physically observed E2 transition rates and quadrupole moments. We find that the distributions of SU(3) representation labels have nearly constant average values for states belonging to some well-defined rotational bands. These are bands of states having B(E2) values and quadrupole moments that follow the predictions of the rotor model. Such bands are interpreted as soft SU(3) bands in parallel with the concept of a soft rotor band with vibrational-shape fluctuations. The concept of a soft SU(3) band and its implications for beta-vibrational excited bands is developed. The average SU(3) representation labels inferred from experiment are interpreted by calculating those implied by the Nilsson model. An analysis of the SU(3) content of Nilsson wave functions also leads to two remarkable predictions. The first is that, in the asymptotic limit, the Nilsson model implies intrinsic states for a rotor band that are beta rigid. The second is that, although the intrinsic Nilsson state is axially symmetric, it generates a sequence of K=0, 2, 4,...bands. (orig.)
Search for short-lived particles produced on nuclei with a heavy liquid mini bubble chamber
2002-01-01
The aim of this experiment is to search for short-lived particles produced in hadronic interactions on nuclei with our high resolution heavy liquid mini bubble chamber BIBC, aiming to establish the cross-section for associated production in hadron-nucleus collisions, its $A$-dependence and an approximate value of the lifetime. The chamber will be operated at a bubble density of 290 bubbles/cm and with an apparent bubble size of 30 $\\mu$m in real space. In test runs at CERN we measured detection efficiencies which, together with simulations of $D\\bar{D}$ production and decay, lead to a sensitivity of 0.25 events/($\\mu$b/N) per day if the lifetime is of the order of $5\\times10^{-13}$s. A null result after 10 days running time would set an upper limit on the production cross section to $3 \\mu$b. \\\\ \\\\ In order to measure the momenta of charged decay products of short-lived particles, the bubble chamber will be placed 1.80 m upstream of the streamer chamber of the NA5 experiment (MPI). The geometrical acceptance ...
International Nuclear Information System (INIS)
Volodichev, N.N.; Savenko, I.A.; Suslov, A.A.
1983-01-01
Surch for short-time growths of fluxes of mainly cosmic heavy nuclei with the energy epsilon > or approximately 500 MeV/nucleon according to measurement data at ''Prognoz-2'' and ''Prognoz-3'' satellites is undertaken. Such growths have been recorded during the flights of the first soviet cosmic rockets, spacecraft-satellites, ''Electron'', ''Molnia-1'' satellites. At the ''Prognoz'' satellite such growth have not been observed. Moreover, the 2.1.1974 growth found at the ''Molnia-1'' satellite by the telescope of scintillation and Cherenkov counters has not been recorded by the analogous device at ''Prognoz-3'' satellite. Therefore, the problem on the nature of short-time growths of the heavy nuclei fluxes remains unsolved
2017-05-22
connecting the three quarks. Composite particles composed of partons are known as “hadrons” and must have a neutral color charge. There are six... neutral charge of neutrons. The up quark has positive charge equivalent to two-thirds the charge of an electron, and the down quark has negative...known as “heavy ions.” An ion is an atom or molecule with net electric charge, bare nuclei have a large positive charge due to the absence of
Heavy quarks and nuclei, or the charm & beauty of nuclear physics
Energy Technology Data Exchange (ETDEWEB)
Kharzeev, D.
1997-09-22
This report contains viewgraphs on the following: why heavy quarks? Heavy quarkonium in QCD vacuum and in matter; Phenomenology of quarkonium production; Induced decay of QCD vacuum in heavy ion collisions? Implications for quarkonium production; and Outlook.
Traces of heavy and superheavy cosmic nuclei in olivins of extraterrestial origin
International Nuclear Information System (INIS)
Ignatova, R.; Taneva, T.
1982-01-01
The paths of traces of WH nuclei from cosmic rays have been measured in olivines from the meteorites Maryalakhti, Eagle Stein, Liposki khutor with radiation ages 175, 45 and 220 million years respectively. 3 cm 3 olivines of these meteorites have been examined and more than 500 traces of nuclei with Z(>=)90 have been found measured including 3 traces 1.5-1.8 times longer than the traces created by the uranium and thorium nuclei. These traces may be left by nuclei with Z(>=)110. The crystals were chosen from localizations situated at 2-7 cm, 8-9 cm and 10-12 cm from the outside atmospheric surface of the meteorite. The abundancy of the Z(>=)50 nuclei in gigantic cosmic rays, averaged for a period of ( =)110 in galactic cosmic rays. It is 1.4 x 10 -9 from that of the iron group nuclei. (authors)
International Nuclear Information System (INIS)
Yasuda, N.; Sekiguchi, M.; Nakamura, S.; Kitamura, T.; Tawara, H.; Doke, T.
2001-01-01
The HNX (Heavy Nuclear eXplorer) project has been tentatively accepted as one of the NASA's Small Explorer (SMEX) Program. Purpose of this project is the measurement of abundances for heavy nuclei in galactic cosmic rays (GCRs). This information will contribute to get a great knowledge for the origin of GCR. HNX has two large and high sensitive detectors, ENTICE (Energetic Trans-Ion Composition Experiment) and ECCO (Extremely Heavy Cosmic-ray Composition Observer). ECCO experimental module consists the large BP-1 glass detectors (total area; 23 m 2 ), will collect the GCRs (∼2,000 events for Pt-group and ∼100 events for actinide) with its high charge resolution (<0.35 e) in space at least 3 years. We report the outline of HNX project and the new techniques for the measurement of large glass detectors. (author)
Charge and velocity resolution of Cerenkov counters in a beam of accelerated heavy nuclei
International Nuclear Information System (INIS)
Cantin, M.; Goret, P.; Jorrand, J.; Jouan, R.; Juliusson, E.; Koch, L.; Maubras, Y.; Mestreau, P.; Petrou, N.; Rio, Y.; Soutoul, A.; Cawood, P.; Linney, A.
1975-01-01
The response of various Cerenkov radiators to oxygen and nitrogen nuclei with energies ranging between 2.1GeV/n and 300MeV/n is presented. The velocity and charge resolutions are analyzed in relation to the possible use of these counters for chemical and isotopic analysis of the primary cosmic ray nuclei [fr
Evaluation of the (n,xn) and (n,xnf) cross sections for heavy nuclei with the statistical model
International Nuclear Information System (INIS)
Jary, J.
1975-01-01
A method was presented to calculate the (n,xn) and (n,xnf) cross sections for the heavy nuclei having mass numbers of 232 1) without fission, according to the law of conventional statistical models, in the (n,xn) process. Fission can also compete with the emission of neutrons and γ-ray for the nuclei and the excitation energy considered. The fission cross sections of 235 U and 238 U recently evaluated by Sowerby and the fission cross section of 236 U have been used to determine the other parameters needed in the calculation. The fission widths of 239 U and 238 U have been obtained by fitting the first-chance and second-chance fission plateaus of the 238 U cross section. For the fission width of 238 U, good agreement was observed between the authors' results and Landrum and others' experimental data. (Iwase, T.)
Experimental determination of the lifetimes and parities of the Yrast states of 60Ni. Study of shape
International Nuclear Information System (INIS)
Moyat, M.-G.
1978-01-01
The two methods used to measure the lifetimes of the Yrast states of 60 Ni are described: the Doppler attenuation method (line deformation) and the recoil range method. The lifetimes obtained for the levels at 2505, 4262, 5345 and 6807 keV are given, together with the transition probabilities inferred. The parities of the 60 Ni high-spin levels measured by the linear polarization method are also given. Finally the recent theoretical approaches relating to the shapes of the nuclei are outlined: K. Kuman's deformed quasi-particle model and the interaction boson approximation of A. Arima and F. Iachello [fr
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
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
International Nuclear Information System (INIS)
Iwasaki, Shin
1984-01-01
Measurements of double differential cross sections (DDX) for several intermediate and heavy nuclei have been performed at 15 MeV in the Dynamitron Laboratory at Tohoku University. Comparison of the experimental data with the evaluated nuclear data file, ENDF/B-IV revealed that the data file could not reproduce the experimental ones, particularly in the angular distributions. Nuclear model calculation showed that the preequilibrium process was important in the present incident energy region. Measurements have been performed for titanium, niobium, molybdenum, lead, and thorium (in progress), including the light elements, carbon and aluminum. (author)
International Nuclear Information System (INIS)
Sukhovoj, A.M.; Khitrov, V.A.; Grigor'ev, E.P.
2002-01-01
The level density and radiative strength functions which accurately reproduce the experimental intensity of two- step cascades after thermal neutron capture and the total radiative widths of the compound states were applied to calculate the total γ-ray spectra from the (n,γ) reaction. In some cases, analysis showed far better agreement with experiment and gave insight into possible ways in which these parameters need to be corrected for further improvement of calculation accuracy for the cascade γ-decay of heavy nuclei. (author)
Energy Technology Data Exchange (ETDEWEB)
Gorelik, M.L.; Shlomo, S. [National Research Nuclear University “MEPhI”, Moscow 115409 (Russian Federation); Cyclotron Institute, Texas A& M University, College Station, TX 77843 (United States); Tulupov, B.A. [National Research Nuclear University “MEPhI”, Moscow 115409 (Russian Federation); Institute for Nuclear Research, RAS, Moscow 117312 (Russian Federation); Urin, M.H., E-mail: urin@theor.mephi.ru [National Research Nuclear University “MEPhI”, Moscow 115409 (Russian Federation)
2016-11-15
The particle–hole dispersive optical model, developed recently, is applied to study properties of high-energy isoscalar monopole excitations in medium-heavy mass spherical nuclei. The energy-averaged strength functions of the isoscalar giant monopole resonance and its overtone in {sup 208}Pb are analyzed. In particular, we analyze the energy-averaged isoscalar monopole double transition density, the key quantity in the description of the hadron–nucleus inelastic scattering, and studied the validity of the factorization approximation using semi classical and microscopic one body transition densities, respectively, in calculating the cross sections for the excitation of isoscalar giant resonances by inelastic alpha scattering.
Study of positive-parity yrast band in 83Rb
International Nuclear Information System (INIS)
Ganguly, S.; Banerjee, P.; Ray, I.; Kshetri, R.; Bhattacharya, S.; Saha Sarkar, M.; Goswami, A.; Muralithar, S.; Singh, R.P.; Kumar, R.; Bhowmik, R.K.
2005-01-01
The properties of the positive-parity yrast band in the odd-A 81,83,85 Rb (Z=37) isotopes show remarkable changes as N increases. The objective of the present work is to study the structure of the lowest positive-parity band in 83 Rb from lifetime studies
Rapid Communication: v= 2 seniority changing transitions in yrast 3 ...
Indian Academy of Sciences (India)
Home; Journals; Pramana – Journal of Physics; Volume 89; Issue 5. Rapid Communication: Δ υ = 2 seniority changing transitions in yrast 3 − states and B ( E 3 ) systematics of Sn isotopes. BHOOMIKA MAHESHWARI SWATI GARG ASHOK KUMAR JAIN. Research Article Volume 89 Issue 5 November 2017 Article ID 75 ...
Bai, Dong; Ren, Zhongzhou
2018-05-01
We study the effects of repulsive four-body interactions of α particles on nuclear α -particle condensates in heavy self-conjugate nuclei using a semianalytic approach, and find that the repulsive four-body interactions could decrease the critical number of α particles, beyond which quasistable α -particle condensate states can no longer exist, even if these four-body interactions make only tiny contributions to the total energy of the Hoyle-like state of 16O. Explicitly, we study eight benchmark parameter sets, and find that the critical number Ncr decreases by |Δ Ncr|˜1 -4 from Ncr˜11 with vanishing four-body interactions. We also discuss the effects of four-body interactions on energies and radii of α -particle condensates. Our study can be useful for future experiments to study α -particle condensates in heavy self-conjugate nuclei. Also, the experimental determination of Ncr will eventually help establish a better understanding on the α -particle interactions, especially the four-body interactions.
Projected shell model description of N = 114 superdeformed isotone nuclei
International Nuclear Information System (INIS)
Guo, R S; Chen, L M; Chou, C H
2006-01-01
A systematic description of the yrast superdeformed (SD) bands in N 114, Z = 80-84 isotone nuclei using the projected shell model is presented. The calculated γ-ray energies, moment of inertia and M1 transitions are compared with the data for which spin is assigned. Excellent agreement with the available data for all isotones is obtained. The calculated electromagnetic properties provide a microscopic understanding of those measured nuclei. Some predictions in superdeformed nuclei are also discussed
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
Energy Technology Data Exchange (ETDEWEB)
Hauschild, K.; Bernstein, L.A.; Becker, J.A. [Lawrence Livermore National Lab., CA (United States)] [and others
1996-12-31
The observation of one-step `primary` gamma-ray transitions directly linking the superdeformed (SD) states to the normal deformed (ND) low-lying states of known excitation energies (E{sub x}), spins and parities (J{sup {pi}}) is crucial to determining the E{sub x} and J{sup {pi}} of the SD states. With this knowledge one can begin to address some of the outstanding problems associated with SD nuclei, such as the identical band issue, and one can also place more stringent restrictions on theoretical calculations which predict SD states and their properties. Brinkman, et al., used the early implementation of the GAMMASPHERE spectrometer array (32 detectors) and proposed a single, candidate {gamma} ray linking the {sup 194}Pb yrast SD band to the low-lying ND states in {sup 194}Pb. Using 55 detectors in the GAMMASPHERE array Khoo, et al., observed multiple links between the yrast SD band in {sup 194}Hg and the low-lying level scheme and conclusively determined E{sub x} and J of the yrast SD states. Here the authors report on an experiment in which Gammasphere with 88 detectors was used and the E{sub x} and J{sup {pi}} values of the yrast SD states in {sup 194}Pb were uniquely determined. Twelve one-step linking transitions between the yrast SD band and low-lying states in {sup 194}Pb have been identified, including the transition proposed by Brinkman. These transitions have been placed in the level scheme of {sup 194}Pb using coincidence relationships and agreements between the energies of the primary transitions and the energy differences in level spacings. Furthermore, measurements of angular asymmetries have yielded the multipolarities of the primaries which have allowed J{sup {pi}} assignments of the {sup 194}Pb SD states to be unambiguously determined for the first time without a priori assumptions about the character of SD bands. A study performed in parallel to this work using the EUROGAM-II array reports similar, but somewhat less extensive, results.
Complete disintegration of heavy nuclei induced by 340 GeV negative pions
International Nuclear Information System (INIS)
Ahmad, T.; Tariq, M.; Irfan, M.; Zafar, M.; Ahsan, M.Z.; Shafi, M.
1989-01-01
The total disintegration of AgBr nuclei caused by 340 GeV negative pions is investigated. The probability of this phenomena depends on the energy of the pion projectile. The angular distributions of grey and black tracks are investigated. Results for the rapidity gap correlation in these catastrophic destructions are also presented. (author). 17 refs., 5 tabs., 9 figs
Choice of the density-dependent effective interaction and alpha decay of heavy spherical nuclei
International Nuclear Information System (INIS)
Kadmenskij, S.G.; Ratis, Yu.L.; Rybak, K.S.; Furman, V.I.
1978-01-01
The parameters of density-dependent effective interaction are studied for some nuclei in the vicinity of a 208 Pb double-magic nucleus. Both nuclei having two nucleons (holes) over magic core and some superfluid nuclei are considered. It is found that the magnitudes of the matrix elements for the zero-range forces (delta forces) are more than three times larger in comparison with the case of the finite-range forces (f forces). Sets of parameters for the effective interaction, which does not lead to the superfluidity of nuclear matter are obtained. Besides, these parameters depend weakly on mass number. It is shown that the attractive part of interaction is substantially larger for the case of f forces than for the delta forces. The theoretical enhancement coefficients for the favoured α decay of 210 Po, 210 Pb and 224 Th nuclei are calculated. For the case of f forces a tendency to saturation of the enhancement coefficients with the increase of the shell-model basis is found
The radiative capture of fast nucleons in the mass area of medium and heavy nuclei
International Nuclear Information System (INIS)
Rigaud, F.
1978-01-01
The radiative capture of 14 MeV neutrons cross-sections on the 59 Co, 93 Nb, 103 Rh, 133 Cs, 139 La, Ce and 159 Tb nuclei were investigated by the integration method and by the activation method on the 27 Al, 50 Ti, 51 V, 103 Rh, 127 I and 139 La nuclei. The gamma-ray spectra following the capture of 8-22 MeV protons on 110 Cd and 115 In nuclei were measured and the single-particle states capture cross-sections deduced. The 110 Cd(p,γ 0 ) 111 In angular distribution was also measured at 13 MeV. The direct and semi-direct processes explained the experimental results. The volume form of the coupling interaction was adequate to account the neutrons results and the surface form to account the 110 Cd(p,γ 0 ) 111 In results. The 110 Cd nuclei electric quadrupole excitation was formed negligible compared with the electric dipole excitation which is adequate to explain the 110 Cd(p,γ 0 ) 111 In excitation function [fr
Studies of the shapes of heavy pear-shaped nuclei at ISOLDE
Energy Technology Data Exchange (ETDEWEB)
Butler, P. A., E-mail: peter.butler@liverpool.ac.uk [Oliver Lodge Laboratory, University of Liverpool, Liverpool L69 7ZE (United Kingdom)
2016-07-07
For certain combinations of protons and neutrons there is a theoretical expectation that the shape of nuclei can assume octupole deformation, which would give rise to reflection asymmetry or a ”pear-shape” in the intrinsic frame, either dynamically (octupole vibrations) or statically (permanent octupole deformation). I will briefly review the historic evidence for reflection asymmetry in nuclei and describe how recent experiments carried out at REX-ISOLDE have constrained nuclear theory and how they contribute to tests of extensions of the Standard Model. I will also discuss future prospects for measuring nuclear shapes from Coulomb Excitation: experiments are being planned that will exploit beams from HIE-ISOLDE that are cooled in the TSR storage ring and injected into a solenoidal spectrometer similar to the HELIOS device developed at the Argonne National Laboratory.
Possibilities of determining the main peculiarities of γ-decay cascades in heavy nuclei. Vol. 2
International Nuclear Information System (INIS)
Ali, M.A.; Khitrov, V.A.; Sukhovoj, A.M.; Vojnov, A.V.
1996-01-01
The main results of an analysis of the average parameters for γ-decay cascades of compound states in complex nuclei, after thermal neutron capture are presented. The experimental data of nuclear level densities, for certain Jπ, at excitation energies above 2 MeV are compared with that predicted by two different theoretical models. Cascade intensities measured over the entire excitation energy range, from the ground state up to the neutron binding energy, are compared with different model predictions. Conclusions about the radiative partial width enhancements for transitions between the compound state and high-lying excited states are given. The problems of estimating the actual temperature of excited nuclei, and of the experimental possibilities to observe phase transitions and their influence on gamma-decay modes are discussed. 12 figs., 2 tabs
Energy Technology Data Exchange (ETDEWEB)
Ali, M A [Nuclear Physics Department, Nuclear Research Center, Atomic Energy Authority, Cairo, (Egypt); Khitrov, V A; Sukhovoj, A M; Vojnov, A V [Joint Institute for Nuclear Research Frank Laboratory of Neutron Physics, Dubna, (Russian Federation)
1996-03-01
The main results of an analysis of the average parameters for {gamma}-decay cascades of compound states in complex nuclei, after thermal neutron capture are presented. The experimental data of nuclear level densities, for certain J{pi}, at excitation energies above 2 MeV are compared with that predicted by two different theoretical models. Cascade intensities measured over the entire excitation energy range, from the ground state up to the neutron binding energy, are compared with different model predictions. Conclusions about the radiative partial width enhancements for transitions between the compound state and high-lying excited states are given. The problems of estimating the actual temperature of excited nuclei, and of the experimental possibilities to observe phase transitions and their influence on gamma-decay modes are discussed. 12 figs., 2 tabs.
Stopped pion absorption by medium and heavy nuclei in the cascade-exciton model
International Nuclear Information System (INIS)
Mashnik, S.G.
1992-03-01
A large variety of experimental data on stopped negative pion absorption by nuclei from C to Bi (energy spectra and multiplicities of n, p, d, t, 3 He and 4 He; angular correlations of two secondary particles; spectra of the energy release in the ''live'' 28 Si target on recording protons, deuterons and tritons in the energy range 40-70 MeV, 30-60 MeV and 30-50 MeV, respectively; isotope yields; momentum and angular momentum distributions of residual nuclei) are analyzed within the framework of the cascade-exciton model of nuclear reactions. Comparison is made with other up-to-date models of the process. The contributions of different pion absorption mechanisms and the relative role of different particle production mechanisms in these reactions are discussed. (author). 59 refs, 13 figs, 4 tabs
Electron-positron pairs in physics and astrophysics: From heavy nuclei to black holes
Ruffini, Remo; Vereshchagin, Gregory; Xue, She-Sheng
2010-02-01
Due to the interaction of physics and astrophysics we are witnessing in these years a splendid synthesis of theoretical, experimental and observational results originating from three fundamental physical processes. They were originally proposed by Dirac, by Breit and Wheeler and by Sauter, Heisenberg, Euler and Schwinger. For almost seventy years they have all three been followed by a continued effort of experimental verification on Earth-based experiments. The Dirac process, e+e-→2γ, has been by far the most successful. It has obtained extremely accurate experimental verification and has led as well to an enormous number of new physics in possibly one of the most fruitful experimental avenues by introduction of storage rings in Frascati and followed by the largest accelerators worldwide: DESY, SLAC etc. The Breit-Wheeler process, 2γ→e+e-, although conceptually simple, being the inverse process of the Dirac one, has been by far one of the most difficult to be verified experimentally. Only recently, through the technology based on free electron X-ray laser and its numerous applications in Earth-based experiments, some first indications of its possible verification have been reached. The vacuum polarization process in strong electromagnetic field, pioneered by Sauter, Heisenberg, Euler and Schwinger, introduced the concept of critical electric field Ec=me2c3/(eħ). It has been searched without success for more than forty years by heavy-ion collisions in many of the leading particle accelerators worldwide. The novel situation today is that these same processes can be studied on a much more grandiose scale during the gravitational collapse leading to the formation of a black hole being observed in Gamma Ray Bursts (GRBs). This report is dedicated to the scientific race. The theoretical and experimental work developed in Earth-based laboratories is confronted with the theoretical interpretation of space-based observations of phenomena originating on cosmological
Isospin asymmetry dependence of the α spectroscopic factor for heavy nuclei
International Nuclear Information System (INIS)
Seif, W. M.; Shalaby, M.; Alrakshy, M. F.
2011-01-01
Both the valence nucleons (holes) and the isospin asymmetry dependencies of the preformation probability of an α-cluster inside parents radioactive nuclei are investigated. The calculations are employed in the framework of the density-dependent cluster model of an α-decay process for the even-even spherical parents nuclei with protons number around the closed shell Z 0 = 82 and neutrons number around the closed shells Z 0 = 82 and Z 0 = 126. The microscopic α-daughter nuclear interaction potential is calculated in the framework of the Hamiltonian energy density approach based on the SLy4 Skyrme-like effective interaction. Also, the calculations based on the realistic effective M3Y-Paris nucleon-nucleon force have been used to confirm the results. The calculations then proceed to find the assault frequency and the α penetration probability within the WKB approximation. The half-lives of the different mentioned α decays are then determined and have been used in turn to find the α spectroscopic factor. We found that the spectroscopic factor increases with increasing the isospin asymmetry of the parent nuclei if they have valence protons and neutrons. When the parent nuclei have neutron or proton holes in addition to the valence protons or neutrons, then the spectroscopic factor is found to decrease with increasing isospin asymmetry. The obtained results show also that the deduced spectroscopic factors follow individual linear behaviors as a function of the multiplication of the valence proton (N p ) and neutron (N n ) numbers. These linear dependencies are correlated with the closed shells core (Z 0 ,N 0 ). The same individual linear behaviors are obtained as a function of the multiplication of N p N n and the isospin asymmetry parameter, N p N n I. Moreover, the whole deduced spectroscopic factors are found to exhibit a nearly general linear trend with the function N p N n /(Z 0 +N 0 ).
The study of initial conditions in collisions of light, intermediate and heavy nuclei
Directory of Open Access Journals (Sweden)
Loctionov A.A.
2017-01-01
Full Text Available The system size dependence for multiparticle processes has been recognized in both cosmic ray (“Stratosphere” collaboration and at accelerator (“EMU” collaboration experiments. The strong enhancement in multiplicity fluctuations for the most central light-light – (C, O, Ne + (C/N/O – collisions has been revealed at JINR-AGS-SPS energies. The sharp difference of light nuclear interactions are interpreted as the sign of intrinsic alpha-clustering in light nuclei.
Influence of proton-skin thickness on the {{\\alpha }} decays of heavy nuclei
Seif, W. M.; Abdurrahman, A.
2018-01-01
We investigate the effect of proton-skin thickness on the α decay process. We consider 188 neutron-deficient nuclei belonging to the isotopic chains from Te (Z = 52) to Pb (Z = 82). The calculations of the half-life are carried out in the framework of the preformed cluster model, with the Wentzel-Kramers-Brillouin penetration probability and assault frequency. It is shown that the proton-skin thickness ({\\varDelta }{{p}}) of the daughter nucleus gives rise to a total α- daughter nucleus interaction potential of relatively wide deep internal pocket and a thinner Coulomb barrier of less height. This increases the penetration probability but decreases the assault frequency. The overall impact of the proton-skin thickness appears as a decrease in the decay half-life. The proton-skin thickness decreases the stability of the nucleus. The half-lives of the proton-skinned isotopes along the isotopic chain decrease exponentially with increasing the proton-skin thickness, whereas the {Q}α -value increases with {\\varDelta }{{p}}. α-decay manifests itself as the second favorite decay mode of neutron-deficient nuclei, next to the {β }+-decay and before proton-decay. It is indicated as main, competing, and minor decay mode, at 21%, 7%, and 57%, respectively, of the investigated nuclei.
Feeding of the superdeformed yrast band in sup 149 Gd
Energy Technology Data Exchange (ETDEWEB)
Haas, B.; Vivien, J.P.; Beck, F.A.; Benet, P.; Byrski, T.; Curien, D.; Duchene, G.; Gehringer, C.; Merdinger, J.C.; Romain, P. (Strasbourg-1 Univ., 67 (France). Centre de Recherches Nucleaires); Basu, S.K. (Strasbourg-1 Univ., 67 (France). Centre de Recherches Nucleaires Bhabha Atomic Research Centre, Calcutta (India). Variable Energy Cyclotron Centre); Kluge, H. (Strasbourg-1 Univ., 67 (France). Centre de Recherches Nucleaires Hahn-Meitner-Institut Berlin GmbH (Germany, F.R.)); Santos, D. (Strasbourg-1 Univ., 67 (France). Centre de Recherches Nucleaires Consejo Nacional de Investigaciones Cientificas y Tecnicas, Buenos Aires (Argentina)); Flibotte, S. (Hahn-Meitner-Institut Berlin GmbH (Germany, F.R.)); Gascon, J.; Taras, P. (Montreal Univ., Quebec (Canada). Lab. de Physique Nucleaire); Bozek, E.; Zuber, K. (Institute of Nuclear Physics, Krakow (Poland))
1990-08-02
The feeding pattern of the superdeformed yrast band in {sup 149}Gd has been found to remain essentially the same, using the {sup 124}Sn+{sup 30}Si reaction at beam energies of 150, 155 and 160 MeV leading to different input angular momenta and excitation energies in the compound nuclear system. This similarity as well as the relative yields of the superdeformed states as a function of beam energy may be understood in terms of the nuclear level density dependence on deformation and the onset of fission. In addition, it has been shown that, at all three beam energies, the selection of high-energy gamma rays does not enhance the yield of the superdeformed yrast states. (orig.).
Yrast four-quasi-particle states in 182W
International Nuclear Information System (INIS)
Regan, P.H.; Walker, P.M.; Dracoulis, G.D.; Anderssen, S.S.; Byrne, A.P.; Davidson, P.M.; Kibedi, T.; Lane, G.J.; Stuchbery, A.E.; Yeung, K.C.
1994-01-01
High-spin states of the stable isotope 182 W have been studied using the reactions 176 Yb( 13 C,α3n) 182 W and 176 Yb( 9 Be,3n) 182 W at beam energies of 65 and 40 MeV, respectively. Three, possibly four, new intrinsic states at high spins have been observed corresponding to different high-K four-quasi-particle structures. The K π =15 + and 17 - levels have lifetimes of 78(15) and 25(10) ns, respectively. Rotational bands are observed built on the K π =16 + and 17 - yrast states. The coupling of Nilsson orbitals which give rise to high-K states at the yrast line and the K-forbiddenness of the K π =15 + isomeric decay are discussed. (orig.)
International Nuclear Information System (INIS)
Li Baoan; Das, Champak B.; Das Gupta, Subal; Gale, Charles
2004-01-01
Using an isospin- and momentum-dependent transport model we study effects of the momentum-dependent symmetry potential on heavy-ion collisions induced by neutron-rich nuclei. It is found that symmetry potentials with and without the momentum-dependence but corresponding to the same density-dependent symmetry energy E sym (ρ) lead to significantly different predictions on several E sym (ρ)-sensitive experimental observables especially for energetic nucleons. The momentum- and density-dependence of the symmetry potential have to be determined simultaneously in order to extract the E sym (ρ) accurately. The isospin asymmetry of midrapidity nucleons at high transverse momenta is particularly sensitive to the momentum-dependence of the symmetry potential. It is thus very useful for investigating accurately the equation of state of dense neutron-rich matter
International Nuclear Information System (INIS)
Schroeder, W.U.; Huizenga, J.R.
1988-08-01
The effect of successively increasing gradients of the potential energy surface on mass and charge transport was studied experimentally and theoretically with a series of damped reactions induced by 48 Ca, 64 Ni, 58 Ni, and 40 Ca projectiles on 238 U targets. Combined transport-evaporation calculations that were performed for the interpretation of data demonstrate a systematic deficiency of quantitative reaction theory. A new type of experimental method has been employed to study several moments of the energy partition in damped reactions, measuring multiplicity correlations of neutrons emitted from the asymptotic fragments with a specially designed, directionally sensitive multiplicity counter. First results indicate significant departures of damped reaction systems from thermal equilibrium. Employing realistic Monte Carlo simulation of published experiments, it was demonstrated that the directions of net mass transfer and energy deposit are uncorrelated in damped reactions. Evaporative and preequilibrium neutron emission has been studied for the asymmetric heavy-ion system 139 La + 40 Ar. The disequilibrium energy transport phenomena observed in the experiment are quantitatively reproduced by model calculations. A strong impact-parameter dependence of preequilibrium emission is demonstrated. The emission patterns of α particles evaporated from high spin compound nuclei, previously attributed to exotic nuclear shapes, have been explained in realistic statistical model calculations for nuclei with conventional shapes. A new octal digital delay module has been designed and tested
Grosse, E.; Junghans, A. R.; Wilson, J. N.
2017-11-01
The basic parameters for calculations of radiative neutron capture, photon strength functions and nuclear level densities near the neutron separation energy are determined based on experimental data without an ad hoc assumption about axial symmetry—at variance to previous analysis. Surprisingly few global fit parameters are needed in addition to information on nuclear deformation, taken from Hartree Fock Bogolyubov calculations with the Gogny force, and the generator coordinator method assures properly defined angular momentum. For a large number of nuclei the GDR shapes and the photon strength are described by the sum of three Lorentzians, extrapolated to low energies and normalised in accordance to the dipole sum rule. Level densities are influenced strongly by the significant collective enhancement based on the breaking of shape symmetry. The replacement of axial symmetry by the less stringent requirement of invariance against rotation by 180° leads to a novel prediction for radiative neutron capture. It compares well to recent compilations of average radiative widths and Maxwellian average cross sections for neutron capture by even target nuclei. An extension to higher spin promises a reliable prediction for various compound nuclear reactions also outside the valley of stability. Such predictions are of high importance for future nuclear energy systems and waste transmutation as well as for the understanding of the cosmic synthesis of heavy elements.
Microscopic study of low-lying yrast spectra and deformation ...
Indian Academy of Sciences (India)
73, No. 4. — journal of. October 2009 physics pp. 657–668. Microscopic study of low-lying yrast spectra and deformation systematics in neutron-rich. 98−106Sr isotopes ... with a large and rigid moment of inertia. 98Sr is predicted to have a ... 2 energy as neutron number N changes from 58 to 60. The onset of deformation in ...
Lifetime Measurement in the Yrast Band of 119I
Lobach, Yu. N.; Pasternak, A. A.; Srebrny, J.; Droste, Ch.; Hagemann, G. B.; Juutinen, S.; Morek, T.; Piiparinen, M.; Podsvirova, E. O.; Toermaenen, S.; Starosta, K.; Virtanen, A.; Wasilewski, A. A.
1999-05-01
The lifetime of levels in the yrast band of 119I were measured by DSAM and RDM using the 109Ag (13C,3n) reaction at E=54 MeV. The detailed description of data analysis including the stopping power determination and estimation of side feeding time is given. A modified method of RDM data analysis --- Recoil Distance Doppler Shape Attenuation (RDDSA) is used.
Lifetime measurement in the yrast band of {sup 119}I
Energy Technology Data Exchange (ETDEWEB)
Lobach, Yu.N. [Institute for Nuclear Research UAS, Kiev (Ukraine); Pasternak, A.A. [A.F. Ioffe Physical Technical Institute RAS, St. Petersbourg (Russian Federation); Srebrny, J. [Nuclear Physics Division, IEP, University of Warsaw, Warsaw (Poland)] [and others
1999-05-01
The lifetime of levels in the yrast band of {sup 119}I were measured by DSAM and RDM using the {sup 109}Ag({sup 13}C,3n) reaction at E = 54 MeV. The detailed description of data analysis including the stopping power determination and estimation of side feeding time is given. A modified method of RDM data analysis - Recoil Distance Doppler Shape Attenuation (RDDSA) is used. (author) 17 refs, 4 figs, 1 tab
Lifetime measurement in the yrast band of 119I
International Nuclear Information System (INIS)
Lobach, Yu.N.; Pasternak, A.A.; Srebrny, J.
1999-01-01
The lifetime of levels in the yrast band of 119 I were measured by DSAM and RDM using the 109 Ag( 13 C,3n) reaction at E = 54 MeV. The detailed description of data analysis including the stopping power determination and estimation of side feeding time is given. A modified method of RDM data analysis - Recoil Distance Doppler Shape Attenuation (RDDSA) is used. (author)
Yrast and high spin states in 22Ne
International Nuclear Information System (INIS)
Szanto, E.M.; Toledo, A.S. de
1982-08-01
High spin states in 22 Ne have been investigated by the reactions 11 B( 13 C,d) 22 Ne and 13 C( 11 B,d) 22 Ne up to E* approximately=19 MeV. Yrast states were observed at 11.02 MeV (8 + ) and 15.46 MeV (10 + ) excitation energy. A backbending in 22 Ne is observed around spin 8 + . The location of high spin states I [pt
International Nuclear Information System (INIS)
Arvieu, Robert
1963-01-01
This research thesis deals with nuclear physics theory, and more particularly with the issues of collective states and matching properties. In a first part, the author presents the formalism and approximations used to obtain individual states and collective states of spherical nuclei, notably by studying the Bogoliubov-Valatin transformation and how it is possible to report matching phenomena, and then by introducing collective modes by means of an approximate diagonalization and of the 'quasi bosons' method. The phenomenon mechanism is described on a simple example, and, in a second part, the theory is applied to the detailed description of tin isotopes by means of finite range interaction
Contributions to the study of heavy and superheavy nuclei stability in alpha-decay
International Nuclear Information System (INIS)
Silisteanu, I.
1978-01-01
Alpha-decay is treated in this work on the complete analogy of transfer reactions by means of nuclear shell models with continuous spectrum nucleons. Certain phenomenologically obtained or microscope evaluated data on low energy interactions between alpha-particles and nuclei, when related to nuclear structure data within the unified theory of nuclear reactions, allow of an improved accuracy in determining the alpha-particle wave function as well as of an estimation of alpha-probabilities in good keeping with experimental ones. The problem of alpha lifetimes thus narrows to the resolution of some homogeneous and inhomogeneous differential equations systems including the optic potential and the alpha formfactors. (author)
Hot nuclei and search for multifragmentation in medium-energy heavy-ion collisions
International Nuclear Information System (INIS)
Doubre, H.
1988-01-01
Some recent determinations of the excitation energies and temperatures of composite systems formed in intermediate-energy heavy-ion collisions are described and the issue of a limiting temperature is discussed. Several examples of experimental investigations of an eventual occurrence of a multifragmentation process are also described
E2 and M1 transition strengths in heavy deformed nuclei revisited
International Nuclear Information System (INIS)
Draayer, J.P.; Popa, G.; Hirsch, J.G.; Vargas, C.E.
2003-01-01
An update on the status of pseudo-SU(3) shell-model calculations in strongly deformed nuclei in the rare earth region is presented. Representative results for energy levels as well as E2 (quadrupole) and M1 (scissors) transitions strengths in 162 Dy (even-even) and 163 Dy (odd-mass) are given. The calculations use realistic single-particle energies and quadrupole-quadrupole and pairing interaction strengths fixed from systematics. The strengths of rotor-like terms included in the Hamiltonian- all small relative to the other terms in the interaction were adjusted to give an overall best fit to the energy spectra. The results present a paradox: for even-even nuclei (integer angular momentum) non-zero pseudo-spin configurations seems to be unimportant while for the odd-mass systems (half-integer angular momentum) pseudo-spin mixing is essential as spin-flip couplings appear to dominate the M1 transition strengths. (Author)
Heavy nuclei far from stability in the N < 126, Z > 82 region
Energy Technology Data Exchange (ETDEWEB)
Back, B.B.; Blumenthal, D.J.; Carpenter, M.P. [and others
1995-08-01
There are long-standing calculations suggesting that nuclei in the N < 126, Z > 82 region far from stability exhibit deformation effects. Away from stability an observable permanent quadrupole deformation should be achieved but, as yet, there is no experimental evidence for such an effect. A series of experiments was performed to assess the production of nuclei in this region and to study their structure. These experiments were performed using gamma-ray spectroscopy to investigate the low-lying level schemes and alpha-particle spectroscopy in order to isolate fine structure in the decay. The low-lying level structure of the neutron-deficient isotope {sup 202}Rn was studied, for the first time, using the {sup 181}Ta({sup 27}Al,6n) and {sup 192}Pt({sup 16}O,6n) reactions. Gamma-ray transitions between excited states in {sup 202}Rn were identified by mass tagging the Fragment Mass Analyzer and by observation of coincident X rays. Transitions in {sup 203}Rn were also identified. The level scheme deduced from these data is consistent with the systematics of light radon isotopes below the N = 126 shell closure and with theoretical calculations indicating that the ground-state shape should not be strongly deformed at N = 116.
International Nuclear Information System (INIS)
Dubach, J.F.
1976-01-01
The purpose of this work is to develop a formalism that will allow one to search the wide variety of transitions presented by nuclei in order to locate situations in which the exchange-current effects are important or dominant and thus allow one to study the contributions of the meson exchanges to the electromagnetic densities within the nucleus. The nuclei studied are assumed to be described in a shell model using harmonic oscillator wave functions. The formalism needed to allow one to do a multipole analysis of these exchange currents within 1s and 1p nuclei is developed. This formalism is then applied to an examination of electron scattering from a series of light nuclei: 3 He, 6 Li, 7 Li, 9 Be, and 10 B. Three significant effects due to the inclusion of exchange currents are seen: (1) The exchange currents can often introduce new structure into the form factors. (2) At larger momentum transfer (700 to 1000 MeV/c) the exchange current contributions to the form factor dominate the simpler one-body form factor by a few orders of magnitude. (3) The exchange currents can excite E4 and M5 multipoles in the p shell which are forbidden to the simpler one-body currents. The elastic scattering of two heavy ions at intermediate and high energies (compared to the Coulomb barrier) is examined in the formalism of the WKB and ''Glauber theory'' approximations. As a concrete example, the scattering of 16 O from 60 Ni is studied assuming an optical-model potential that fits elastic scattering data at low energies. One immediate result is that the WKB approximation agrees quite well with ''exact'' numerical calculations at energies as low as 60 MeV. The Glauber theory fails below about 1 GeV but correction terms are developed that can extend the usefulness of the Glauber theory to much lower energies. The model problem of scattering from a black-sphere model of the nucleus is briefly examined
Impact of spin-orbit density dependent potential in heavy ion reactions forming Se nuclei
Energy Technology Data Exchange (ETDEWEB)
Rajni; Sharma, Ishita; Sharma, Manoj K. [Thapar University, School of Physics and Materials Science, Patiala (India); Jain, Deepika [Mata Gujri College, Department of Physics, Fatehgarh Sahib (India)
2017-10-15
The Skyrme energy density formalism is employed to explore the effect of spin-orbit interaction potential by considering a two nucleon transfer process via various entrance channels such as {sup 23}Na + {sup 49}V, {sup 25}Mg + {sup 47}Ti, {sup 27}Al + {sup 45}Sc, {sup 29}Si + {sup 43}Ca and {sup 31}P + {sup 41}K, all forming the same compound system {sup 72}Se*, using both spherical as well as quadrupole deformed (β{sub 2}) nuclei. For spherical nuclei, the spin-orbit density part V{sub J} of nuclear potential remains unaffected with the transfer of two nucleons from the target to the projectile, however, show notable variation in magnitude after inclusion of deformation effects. Likewise, deformations play an important role in the spin-orbit density independent part V{sub P}, as the fusion pocket start appears, which otherwise diminish for the spherical nuclei. Further, the effect of an increase in the N/Z ratio of Se is explored on V{sub J} as well as V{sub P} and results are compared with transfer channels. In addition to this, the role of double spin-orbit parameters (W{sub 0} and W{sub 0}{sup '}) with relative contribution of the isoscalar and isovector parts of spin-orbit strength is explored in view of SkI2, SkI3 and SkI4 Skyrme forces. Beside this, the decay path of {sup 72}Se* nucleus formed in {sup 27}Al + {sup 45}Sc reaction is investigated within the framework of dynamical cluster decay model (DCM), where the nuclear proximity potential is obtained by both Skyrme energy density formalism (SEDF) and proximity pocket formula. The fusion hindrance in the {sup 27}Al + {sup 45}Sc reaction is also addressed via the barrier lowering parameter ΔV{sub B}. Finally, the contribution of spin-orbit density dependent interaction potential is estimated for the {sup 27}Al + {sup 45}Sc reaction using single (W{sub 0} or W{sub 0}{sup '}) and double spin-orbit parameters (W{sub 0} and W{sub 0}{sup '}). (orig.)
International Nuclear Information System (INIS)
Birbrair, B.L.; Gridnev, A.B.; Il'in, A.I.
1984-01-01
A two-shoulder time-of-flight spectrometer has been used to investigate deep inelastic disintegration of heavy nuclei by 1 GeV protons. Masses, kinetic energies and momenta of two additional massive fragments dispersing perpendicularly to a primary proton beam were measured in the experiment. Events with essential nucleon losses (up to 100 a.u.m.) are stated to be characterized by increased total kinetic energy of fragments and noticeable value of transferred and transverse momenta as well (up to 2-3 GeV/c). These kinematic peculiarities testify to presence of a special mechanism of heavy nucleus disintegration followed by essential nucleon losses. The threshold value of nucleon losses (45+-5) a.u.m. corresponding to transition from ordinary high-energy pressure after intranuclear cascade to a new mechanism of nuclear reaction is determined. The main peculiarity of the new mechanism is that a group of nucleons receiving essential part of energy and momentum of an incident particle is separated inside the nucleus. The physical reason for this collective mechanism of interaction can be associated with production of pion bubbles inside the nucleus under pion interaction with a nucleus regarded as a relativistic nucleon system
International Nuclear Information System (INIS)
Rahmani, A.
1988-12-01
The study of the proton's production differential cross sections, in the collision of relativistic heavy ions, allows to obtain the nuclear-matter temperature and gives information about the nucleons large burst pulses in the nucleus. The chosen thermodynamic model is a generalized approach of the R. Hagedorn model, applied to heavy ions collisions: the nuclear matter is divided in volume elements δV assumed to be in thermal and chemical equilibrium and emitting particles and fragments isotropically, inside their own system. The applied nuclear-matter velocity distribution depended only on the impact parameter and on the relationship between the chemical potential and the temperature. The predictions of this thermodynamic model were compared to the Saturne experimental results, using Diogene detector. The obtained temperature values are similar to those given by D. Hahn and H. Stoker. The proton production cross sections were measured for backward emitting angles. A relationship between the cross sections and the burst pulse distribution in the nuclei was settled [fr
Energy Technology Data Exchange (ETDEWEB)
Schroeder, W.U.
1993-08-01
This report contain papers on the following topics: The Cold-Fusion Saga; Decay Patterns of Dysprosium Nuclei Produced in {sup 32}S + {sup 118,124}Sn Fusion Reactions; Unexpected Features of Reactions Between Very Heavy Ions at Intermediate Bombarding Energies; Correlations Between Neutrons and Charged Products from the Dissipative Reaction {sup 197}Au+{sup 208}Pb at E/A = 29 MeV; Dissipative Dynamics of Projectile-Like Fragment Production in the Reaction {sup 209}Bi+{sup 136}Xe at E/A = 28.2 MeV; Dynamical Production of Intermediate-Mass Fragments in Peripheral {sup 209}Bi+{sup 136}Xe Collisions at E{sub lab}/A = 28.2 MeV; The Rochester 960-Liter Neutron Multiplicity Meter; A Simple Pulse Processing Concept for a Low-Cost Pulse-Shape-Based Particle Identification; A One-Transistor Preamplifier for PMT Anode Signals; A Five-Channel Multistop TDC/Event Handler for the SuperBall Neutron Multiplicity Meter; Construction of the SuperBall -- a 16,000-Liter Neutron Detector for Calorimetric Studies of Intermediate-Energy Heavy-Ion Reactions; A Computer Code for Light Detection Efficiency Calculations for Photo-multipliers of a Neutron Detector; Evaluation of Gd-Loaded Liquid Scintillators for the SuperBall Neutron Calorimeter; and Measurement of the Interaction of Cosmic-Ray {mu}{sup {minus}} with a Muon Telescope.
High mass asymmetry in spontaneous and induced desintegration of heavy nuclei
International Nuclear Information System (INIS)
Tavares, O.A.P.
1978-01-01
The experimental and theoretical results related to a new rupture mode of heavy ions (A>230) in mass fragments more different than ordinary ission products, are presented and disussed. Experiences of long exposure time by nuclear emulsion technique, show that, the U 238 is also a spontaneous emitter of ions with mass number between 20 and 70. The results are interpreted as a high mass asymmetry in fission process or as a nucleon cluster emission mechanism by potential barrier penetration. Preliminary estimation show good agreement with experimental results for U 238 . Glass laminas with uranium thin films prepared 16 years ago, are also analysed aiming to confirm these results. Several experiences with nuclear emulsions and mica sandwich, and radiochemical data show to be possible heavy ion emission from U 238 induced by photons of low energy as well as neutrons of reactor (M.C.K.) [pt
Low energy level density and surface instabilities in heavy transition nuclei
International Nuclear Information System (INIS)
Wieclawik, W. de; Foucher, R.; Dionisio, J.S.; Vieu, C.; Hoglund, A.; Watzig, W.
1975-01-01
A statistical analysis of Au, Pt, Hg nuclear levels was performed with Ericson's method. The odd mass gold experimental number of levels distributions are compared to the theoretical distributions corresponding to vibrational (Alaga and Kisslinger-Sorensen) and rotational (Stephens, Meyer-ter-Vehn) models. The Alaga model gives the most complete description of 193 Au, 195 Au levels and fits the lowest part of Gilbert-Cameron high energy distributions (deduced from the statistical model and neutron capture data). The Ericson's method shows other interesting features of Pt and Hg isotopes (i.e. level density dependence on nuclear shape and pairing correlations, evidence for phase transitions). Consequently, this method is a useful tool for guiding experimental as well as theoretical investigations of transition nuclei [fr
Soft radiative strength in warm nuclei
International Nuclear Information System (INIS)
Becker, J A; Bernstein, L A; Garrett, P E; Nelson, R O; Schiller, A; Voinov, A; Agvaanluvsan, U; Algin, E; Belgya, T; Chankova, R; Guttormsen, M; Mitchell, G E; Rekstad, J; Siem, S
2004-01-01
Unresolved transitions in the nuclear γ-ray cascade produced in the decay of excited nuclei are best described by statistical concepts: a continuous radiative strength function (RSF) and level density yield mean values of transition matrix elements. Data on the soft (E γ < 3-4 MeV) RSF for transitions between warm states (i.e. states several MeV above the yrast line) have, however, remained elusive
Heavy-ion research at the tandem and superconducting linac accelerators
International Nuclear Information System (INIS)
Anon.
1980-01-01
The heavy-ion research program at the Argonne Physics Division is principally aimed at the study of nuclear structure and its manifestation in heavy-ion induced nuclear reactions. In order to extract information on nuclear structure, measurements with high precision often need to be performed. Such measurements are now carried out at the tandem-linac accelerator over a wide energy range. The investigation of high-spin states near the yrast line has provided much new information on the behavior of nuclei at high angular momentum. Argonne work has concentrated on nuclei where high-spin isomers, the so-called yrast traps, are prevalent. The resonance effects observed previously in the 24 Mg( 16 O, 12 C) 28 Si reactions have been further explored through both additional measurements and a new quantitative method of analysis. The measurements were extended in energy and angular range and to various exit channels as well as similar systems. Several measurements were performed to investigate the reaction mechanisms in heavy-ion induced reactions and to map out the distribution of reaction strength as a function of energy and target-projectile masses energy regions previously not accessible. The behavior of the quasi- and deep-inelastic reaction cross sections was studied as a function of energy for medium-heavy systems, the production of inclusive alpha-particle yields for 16 O beams at energies E/A greater than or equal to 5 MeV/nucleon, and excitation functions, mass and kinetic energy distributions for heavy-ion induced fusion-fission reactions
Resonant heavy-ion elastic scattering from s-d shell nuclei
International Nuclear Information System (INIS)
DeVries, R.M.
1978-01-01
Angular distributions at angles 130 less than theta/sub cm/ less than 180 0 were measured for 12 C + 28 Si, 32 S, 40 Ca as well as 9 Be, 13 C + 28 Si in the energy range 20 MeV less than or equal to E/sub cm/ less than or equal to 35 MeV. Cross sections rising towards 180 0 are observed for all reactions. Excitation functions for the back-angle enhancement show distinct structures, most pronounced for 12 C + 28 Si. Angular distributions for 12 C, especially those corresponding to peaks in the excitation function show oscillations of the type vertical bar P/sub J/(cos theta) vertical bar 2 . The 12 C back-angle enhancement decreases with target mass. Backscattering of the nonalpha nuclei 9 Be and 13 C is reduced by about two orders of magnitude in comparison with 12 C. Similar measurements for the 28 Si( 12 C, 16 O) 24 Mg reaction and 16 O + 24 Mg elastic scattering allow comparison of reaction data with the corresponding entrance and exit channel data. Standard theoretical approaches fail to explain all the observed effects
The boson expansion theory as the nuclear structure theory for the heavy nuclei
International Nuclear Information System (INIS)
Kim, H.B.
1987-01-01
Sometime sago, Kishimoto and Tamura developed a formalism of boson expansion theory (BET), and then Weeks and Tamura showed that it fitted many experimental data of collective nuclei. This formalism has recently been simplified significantly be Pedrocchi, Jamaluddin and Tamura. The new and old theories are very closely related but are not exactly the same. It has thus been desired to see whether the new theory can also fit data, and to show that it indeed works well constitutes a major part of this thesis. It is in fact seen that a number of data of Sm, Os and Pt isotopes are explained nicely. Since the new form of the theory is rather simple, it permits us to take into account easily the effects of noncollective states to the behavior of collective states. This thesis shows that are remarkably improved fit to data of magnetic moments of SM isotopes is achieved in this way. The thesis discusses one additional subject. It is a result of an effort made to improve the BET by removing as much as possible the error due to the use of the BCS theory. This was done by applying a method developed by Li to the Dyson form of BET. A way to develop this work further is suggested
Deep-hole and high-lying particle states in heavy nuclei
International Nuclear Information System (INIS)
Gales, S.
1985-01-01
Our present knowledge on single-particle strength functions from one nucleon transfer reactions is reviewed. Results on deeply-bound neutron hole states in the Sn and Pb region are discussed with emphasis on the investigation of a very large excitation energy range. The first measurements on the γ-decay of deeply-bound hole states in the Sn isotopes are reported. High energy neutron and proton stripping reactions are used to study the particle response function. These reactions are particularly well suited to the study of high-spin outer subshells. For the proton states, the behaviour of the 1h 11/2 and 1i 13/2 strength distributions, as a function of deformation in the Sm region, is discussed. Strong transitions to high-lying neutron states are observed in the 112, 116, 118, 120, 122, 124 Sn and 208 Pb nuclei. The empirical systematics for both proton and neutron particle strength distributions are compared to the predictions from the quasi particle-phonon and the single-particle vibration coupling nuclear models. (orig.)
Independent yields of Kr and Xe isotopes in the photofission of heavy nuclei
International Nuclear Information System (INIS)
Gangrsky, Yu.P.; Zhemenik, V.I.; Maslova, N.Yu.; Mishinsky, G.V.; Penionzhkevich, Yu.E.; Szoelloes, O.
2003-01-01
The yields of Kr (A = 87-93) and Xe (A = 138-143) primary fission fragments produced in 232 Th, 238 U, and 244 Pu photofission upon the scission of a target nucleus and neutron emission were measured in an experiment with bremsstrahlung from electrons accelerated to 25 MeV by a microtron, and the results of these measurements are presented. The experimental procedure used involved the transportation of fragments that escaped from the target by a gas flow through a capillary and the condensation of Kr and Xe inert gases in a cryostat at liquid-nitrogen temperature. The fragments of all other elements were retained with a filter at the capillary inlet. The isotopes of Kr and Xe were identified by the γ spectra of their daughter products. The mass-number distributions of the independent yields of Kr and Xe isotopes are obtained and compared with similar data on fission induced by thermal and fast neutrons; the shifts of the fragment charges with respect to the undistorted charge distribution are determined. Prospects for using photofission fragments in studying the structure of highly neutron-rich nuclei are discussed
The proton-neutron symmetry in collective excitation of medium-heavy nuclei
International Nuclear Information System (INIS)
Frank, W.
1990-01-01
In the present thesis explicit formulas were given, which allow the projection of arbitrary one- and two-particle IBM-2 operators to IBM-1 operators, i.e. the results are not confined to the usual sd or sdg space, but are valid for arbitrary spatial multipolarities of the bosons. By this projection of the Hamiltonian and the transition operators could be derived. Explicitely the sd and sdg Hamiltonian were treated. By the projection formalism the dependence of the M1 and E2 matrix elements on the boson numbers N π and N ν could be determined if their sum is constant. The nuclei with constant total boson number form a F-spin multiplet. The results were applied to the A ≅ 50 region. In order to test the correctness of the projection formulae comprehensive, numerical tests for the sd case were performed. The projection method is valid for practical application, as far as the F spin is a good quantum number. A large number of experimental data shows that the F spin is approximatively conserved. As example served the analysis of 58 Fe. (orig./HSI) [de
TIMS-1: a processing code for production of group constants of heavy resonant nuclei
International Nuclear Information System (INIS)
Takano, Hideki; Ishiguro, Yukio; Matsui, Yasushi.
1980-09-01
The TIMS-1 code calculates the infinitely dilute group cross sections and the temperature dependent self-shielding factors for arbitrary values of σ 0 and R, where σ 0 is the effective background cross section of potential scattering and R the ratio of the atomic number densities for two resonant nuclei if any. This code is specifically programmed to use the evaluated nuclear data file of ENDF/B or JENDL as input data. In the unresolved resonance region, the resonance parameters and the level spacings are generated by using Monte Carlo method from the Porter-Thomas and Wigner distributions respectively. The Doppler broadened cross sections are calculated on the ultra-fine lethargy meshes of about 10 -3 -- 10 -5 using the generated and resolved resonance parameters. The effective group constants are calculated by solving the neutron slowing down equation with the use of the recurrence formula for the neutron slowing down source. The output of the calculated results is given in a format being consistent with the JAERI-Fast set (JFS) or the Standard Reactor Analysis Code (SRAC) library. Both FACOM 230/75 and M200 versions of TIMS-1 are available. (author)
International Nuclear Information System (INIS)
Brandt, R.
1999-01-01
The paper is based on the report presented at the 85th Session of the JINR Scientific Council. Some aspects of experimental studies of the problem of reprocessing radioactive wastes by means of transmutation in the fields of neutrons generated by relativistic particle beams are discussed. Research results on measurement of neutron yields in heavy targets irradiated with protons at energies up to 3.7 GeV as well as transmutation cross sections of some fission products (I-129) and actinides (Np-237) using radiochemical methods, activation detectors, solid state nuclear track detectors and other methods are presented. Experiments have been performed at the accelerator complex of the Laboratory of High Energies, JINR. Analogous results obtained by other research groups are also discussed
Studies of heavy ion reactions and transuranic nuclei. Progress report, August 1, 1979-July 31, 1980
International Nuclear Information System (INIS)
Huizenga, J.R.
1980-07-01
The study of heavy-ion reaction mechanisms at the SuperHILAC and LAMPF is reported. Preprints of five articles and manuscripts of four recent conference papers are given, along with complete citations of publications and a list of personnel. Significant work was performed in the following areas: the bombarding energy dependence of the 209 Bi + 136 Xe reaction; the fragment yields for specific Z and A for projectile-like fragments produced in the reaction of 8.3-MeV/u 56 Fe ions with targets of 56 Fe, 165 Ho, 209 Bi, and 238 U; and time distributions of fragments from delayed fission after muon capture for muonic 235 U, 238 U, 237 Np, 239 Pu, and 242 Pu
High-spin isomer in 211Rn, and the shape of the yrast line
International Nuclear Information System (INIS)
Dracoulis, G.D.; Fahlander, C.; Poletti, A.R.
1981-08-01
High spin yrast states in 211 Rn have been identified. A 61/2 - , 380 ns isomer found at 8856 keV is characterised as a core-excited configuration. The average shape of the yrast line shows a smooth behaviour with spin, in contrast to its neighbour 212 Rn. This difference is attributed to the presence of the neutron hole
Two-proton decays from light to heavy nuclei - Comparison of theory and experiment
International Nuclear Information System (INIS)
Grigorenko, L. V.; Zhukov, M. V.
2009-01-01
Two-proton (2p) radioactivity was predicted by V.I. Goldansky in 1960 [1] as an exclusively quantum-mechanical phenomenon. True three-body decay, in his terms, is a situation where the sequential emission of the particles is energetically prohibited from the ground state of a nucleus and all the final-state fragments are emitted simultaneously. Since the experimental discovery of the 4 6F e two-proton radioactivity in 2002 [2,3], this field has made fast progress. New cases of 2p radioactivity were found for 6 4Z n [4], 1 9M g [5], and, maybe, 4 8N i [6]. The 2p correlations were recently measured for the ground state decays of 4 6F e [7], 1 9M g [5,8], 1 6N e [8], and 6 B e [9]. All these decays exhibit complex correlation patterns. These correlation patterns are well described within the three-cluster theory of two-proton radioactivity (see Ref. [9] and Refs. therein); the example of the 6 B e ground state decay is provided in Fig. 1. The correlations are shown to be sensitive to the details of structure and nuclear interactions. Thus experimental studies of correlations can provide important information about the structure of decaying nuclei. With lifetimes and correlations well described by the theory in a broad range of nuclear masses (6 B e, 1 9M g, and 4 6F e belong to p, s-d, and p-f shells respectively) understanding of the nature of 2p radioactivity is getting now a solid empirical support. This is specially important in the view of astrophysical implementations of the three-body decay theory for the inverse processes of the three-body radiative capture in astrophysics, which seem to be not completely understood so far.(author)
Study of yrast structures in {sup 55,57}Cr
Energy Technology Data Exchange (ETDEWEB)
Gupta, Anuradha, E-mail: annu1gupta1@gmail; Kumar, Amit, E-mail: akbcw2@gmail.com [Research Scholar, University of Jammu, Jammu-180006 (India); Singh, Suram, E-mail: suramsingh@gmail.com [Assistant Professor, Department of Physics, G.D.C. Kathua, 184101 (India); Bharti, Arun, E-mail: arunbharti-2003@yahoo.co.in [Professor, University of Jammu, Jammu-180006 (India)
2016-05-06
The characteristic nuclear structure properties of yrast bands of {sup 55,57}Cr have been investigated by using two body effective interactions incorporated in phenomenological axial framework. In order to check the validity of the chosen framework as well as chosen valence space, the calculated results are compared with the available experimental data and a good agreement has been found from the comparison. The back-bending in moment of inertia has also been studied and attributed to the alignment of odd g{sub 9/2} neutron along the rotation axis.
Conversion coefficients and yrast state spins in 180Os
International Nuclear Information System (INIS)
Dracoulis, G.D.; Kibedi, T.; Byrne, A.P.; Fabricius, B.; Stuchbery, A.E.
1989-11-01
Internal conversion coefficients of transitions in 180 Os have been measured using a superconducting, solenoidal electron spectrometer, operated in the lens mode. The high energy resolution and efficiency allow a precise measurement of the conversion coefficients of the 528 keV yrast transition. The values obtained, α K = 0.015 (2), α L = 0.004(1) define pure E2 multipolarity. Taken with the measured γ-ray angular distribution, the conversion coefficient leads to an unambiguous assignment of 16 + →14 + for the 528 keV transition. 14 refs., 5 figs., 1 tab
International Nuclear Information System (INIS)
Anni, R.; Taffara, L.
1976-01-01
A fictitious scattering phenomenon between neutral heavy particles is analysed by using both the square-well and trapezoidal complex potentials. After a preliminary phenomenological discussion based on the behaviour of the exact scattering matrix and the trajectories of Regge poles and zeros as continuous functions of the imaginary part of the potential, the contributions to the scattering amplitude from the external and multiple internal reflections and from the ''surface waves'' are separated by using the Debye expansion of the S(lambda)-matrix. The most important first two terms of this expansion are then compared with the exact behaviour of both the partial-wave scattering amplitude and cross-section, and the results are discussed. In particular, for potentials with large imaginary parts, the first term of the Debye expansion, which is associated with the rays directly reflected by the surface, well approximates the exact scattering matrix for all angular momenta. In these cases, by applying to this first term the Watson transformation, one is able to separate the contributions from the reflected rays (saddle-point contribution in the background integral)from that of the surface waves(surface pole contribution) which are responsible for the diffraction phenomenon. Studies are in progress in order to extend this approach to the Saxon-Wood potential with Coulomb interaction
International Nuclear Information System (INIS)
PIGNI, M.T.; HERMAN, M.; OBLOZINSKY, P.
2008-01-01
We produced a large set of neutron cross section covariances in the energy range of 5 keV-20 MeV. The present set of data on 57 structural materials and 31 heavy nuclei follows our earlier work on 219 fission product materials and completes our extensive contribution to the low-fidelity covariance project (307 materials). This project aims to provide initial, low-fidelity yet consistent estimates of covariance data for nuclear criticality safety applications. The evaluation methodology combines the nuclear reaction model code EMPIRE which calculates sensitivity to nuclear reaction model parameters, and the Bayesian code KALMAN that propagates uncertainties of the model parameters to cross sections. Taking into account the large scale of the project, only marginal reference to experimental data was made. The covariances were derived from the perturbation of several key model parameters selected by the sensitivity analysis. These parameters refer to the optical model potential, the level densities and the strength of the pre-equilibrium emission. This work represents the first attempt ever to generate nuclear data covariances on such a large scale
Directory of Open Access Journals (Sweden)
O. A. Ponkratenko
2015-10-01
Full Text Available Diffraction range of available experimental differential cross sections of heavy ions on light nuclei elastic scattering for 17 pairs of the interacting nuclei with 4 ≤ А ≤ 20 have been analyzed in the projectile energy wide interval from 1 to 100 МеV/nucleon. Diffraction maxima and minima positions in the transferred momentum coordinates depending on projectile energy demonstrate smooth behavior at energies higher 2 - 4 МeV/nucleon, and practically do not depend on energy at energies up to 30 - 40 МеV/nucleon. These energy dependences of maxima (minima positions can be parameterized by simple functions. It was found the suitable approximations that describe reasonably the energy dependence of the maxima (minima positions of the experimental elastic scattering differential cross sections. These approximations were evaluated with the same parameters for all colliding nuclei groups.
International Nuclear Information System (INIS)
Ponkratenko, O.A.; Pyirnak, Val. M.; Rudchik, A.A.; Stepanenko, Yu.M.; Uleshchenko, V.V.; Shirma, Yu.O.
2015-01-01
Diffraction range of available experimental differential cross sections of heavy ions on light nuclei elastic scattering for the interactive nuclei 17 pairs with 4 ≤ A ≤ 20 have been analyzed in the projectile energy wide interval from 1 to 100 MeV/nucleon. Diffraction maxima and minima positions in the transferred momentum coordinates depending on projectile energy demonstrate smooth behavior at energies higher 2 - 4 MeV/nucleon and at energies to 30 - 40 MeV/nucleon - practically does not depend on energy. These energy dependences of maxima (minima) position. can be parameterized by simple functions. It was found the suitable approximations that describe reasonable the energy dependence of the maxima (minima) positions of the experimental elastic scattering differential cross sections. These approximations were evaluated with the same parameters for all colliding nuclei groups
Energy Technology Data Exchange (ETDEWEB)
Koh, Meng-Hock [Universiti Teknologi Malaysia, Skudai, Johor (Malaysia); Univ. Bordeaux, CENBG, UMR5797, Gradignan (France); CNRS, IN2P3, CENBG, UMR5797, Gradignan (France); Duc, Dao Duy [Ton Duc Thang University, Division of Nuclear Physics, Ho Chi Minh City (Viet Nam); Ton Duc Thang University, Faculty of Applied Sciences, Ho Chi Minh City (Viet Nam); Nhan Hao, T.V. [Duy Tan University, Center of Research and Development, Danang (Viet Nam); Hue University, Center for Theoretical and Computational Physics, College of Education, Hue City (Viet Nam); Long, Ha Thuy [Hanoi University of Sciences, Vietnam National University, Hanoi (Viet Nam); Quentin, P. [Universiti Teknologi Malaysia, Skudai, Johor (Malaysia); Univ. Bordeaux, CENBG, UMR5797, Gradignan (France); CNRS, IN2P3, CENBG, UMR5797, Gradignan (France); Ton Duc Thang University, Division of Nuclear Physics, Ho Chi Minh City (Viet Nam); Bonneau, L. [Univ. Bordeaux, CENBG, UMR5797, Gradignan (France); CNRS, IN2P3, CENBG, UMR5797, Gradignan (France)
2016-01-15
In four well-deformed heavy odd nuclei, the energies of low-lying rotational band heads have been determined microscopically within a self-consistent Hartree-Fock-plus-BCS approach with blocking. A Skyrme nucleon-nucleon effective interaction has been used together with a seniority force to describe pairing correlations. Only such states which are phenomenologically deemed to be related to single-particle excitations have been considered. The polarization effects, including those associated with the genuine time-reversal symmetry breaking have been fully taken into account within our model assumptions. The calculated spectra are in reasonably good qualitative agreement with available data for the considered odd-neutron nuclei. This is not so much the case for the odd-proton nuclei. A potential explanation for such a difference in behavior is proposed. (orig.)
International Nuclear Information System (INIS)
Aarts, H.J.M.
1981-01-01
Detailed γ-ray spectroscopy of high-spin states is hampered by transitions with low intensity on a high γ-ray background. An approach to enhance weak peaks in a spectrum in the reduction of the Compton background by means of a Compton-suppression spectrometer (CSS). Optimization of a CSS by means of Monte Carlo calculations is described. The investigation of high-spin states in the sd-shell nucleus 38 Ar with a Compton-suppression spectrometer is reported. With previously described techniques, in combination with p-γ coincidence measurements to establish an unambiguous level scheme, states up to Jsup(π) = 11 - could be identified and investigated. A gamma-gamma coincidence experiment on the nuclei 167 168 Hf is described with two Compton-suppression spectrometers. Yrast bands are followed, beyond the region of the first backbending, up to spin J = 37/2 and J = 28 for 167 Hf and 168 Hf, respectively. (Auth.)
Three band crossings in the yrast structure of 162Hf
International Nuclear Information System (INIS)
Bingham, C.R.; Riedinger, L.L.; Courtney, L.H.
1988-01-01
The yrast sequence of 162 Hf has been observed up to a level tentatively assigned as 38 + and reveals a continuing rotational character up to that spin. Sharp backbends at rotational frequencies of 0.27 and 0.42 MeV/ℎ are attributed to isub(13/2) neutron and hsub(11/2) proton alignments, respectively. A gradual increase in the aligned angular momentum of the yrast levels between these two sharp backbends is attributed to the rotational alignment of a pair of negative parity quasineutrons (mostly hsub(9/2) in character). The interpretation of this effect is supported by the failure of the negative parity bands, which already contain this aligned hsub(9/2) neutron, to gain alignment in the same rotational frequency range. While the alignment of the hsub(9/2) quasineutrons has been predicted in the cranked shell model to occur in the rare-earth region with a large interaction strength, this represents the first clear observation of such a band crossing. (author)
Population of yrast states in 191Os using deep-inelastic reactions
Jones, G. A.; Podolyák, Zs; Walker, P. M.; Regan, P. H.; de Angelis, G.; Axiotis, M.; Bazzacco, D.; Bizzeti, P. G.; Brandolini, F.; Broda, R.; Bucurescu, D.; Farnea, E.; Gelletly, W.; Gadea, A.; Ionescu-Bujor, M.; Iordachescu, A.; Kröll, Th; Langdown, S. D.; Lunardi, S.; Marginean, N.; Martinez, T.; Medina, N. H.; Quintana, B.; Rubio, B.; Ur, C. A.; Valiente-Dobón, J. J.; Williams, S. J.; Zhang, Y. H.
2005-10-01
Several nuclei in the A ~ 190 region have been studied following deep-inelastic reactions using a 460 MeV 82Se projectile impinging upon a thick 192Os target. The GASP array (at the Legnaro National Laboratory in Italy) was used to measure the resulting γ-decays. The previously reported near-yrast structure of 191Os is extended to a t\\frac{1{2}} = 61 ns isomer, at an energy of 2640 keV. Branching ratios for ΔI = 1 and ΔI = 2 transitions in the Kπ =\\frac{11}{2}+ band have been measured, giving |(gK - gR)/Q0| = 0.022(3) and 0.024(7) for transitions from the \\frac{17}{2}+ and \\big(\\frac{19}{2}^+\\big) states respectively. These are consistent with the theoretical calculation for the proposed ν11/2+[615] configuration of the band. Nilsson plus BCS calculations reveal that the isomer is likely to have a {ν11/2+[615] π11/2-[505] π9/2-[514]} configuration with Jπ =Kπ =\\frac{31}{2}+ . This yields an implied reduced hindrance of fν= 1.9, in accordance with empirical systematics of K isomers in the A ~ 180-190 region.
Energy Technology Data Exchange (ETDEWEB)
Atchison, F.
1998-09-01
The PSIMECX library contains calculated nuclide production cross-sections from neutron-induced reactions in the energy range about 2 to 800 MeV in the following 72 stable isotopes of 24 elements: {sup 12}C, {sup 13}C, {sup 16}O, {sup 17}O, {sup 18}O, {sup 23}Na, {sup 24}Mg, {sup 25}Mg, {sup 26}Mg, {sup 27}Al, {sup 28}Si, {sup 29}Si, {sup 30}Si, {sup 31}P, {sup 32}S, {sup 33}S, {sup 34}S, {sup 36}S, {sup 35}Cl, {sup 37}Cl, {sup 39}K, {sup 40}K, {sup 41}K, {sup 40}Ca, {sup 42}Ca, {sup 43}Ca, {sup 44}Ca, {sup 46}Ca, {sup 48}Ca, {sup 46}Ti, {sup 47}Ti, {sup 48}Ti, {sup 49}Ti, {sup 50}Ti, {sup 50}V, {sup 51}V, {sup 50}Cr, {sup 52}Cr, {sup 53}Cr, {sup 54}Cr, {sup 55}Mn, {sup 54}Fe, {sup 56}Fe, {sup 57}Fe, {sup 58}Fe, {sup 58}Ni, {sup 60}Ni, {sup 61}Ni, {sup 62}Ni, {sup 64}Ni, {sup 63}Cu, {sup 65}Cu, {sup 64}Zn, {sup 66}Zn, {sup 67}Zn, {sup 68}Zn, {sup 70}Zn, {sup 92}Mo, {sup 94}Mo, {sup 95}Mo, {sup 96}Mo, {sup 97}Mo, {sup 98}Mo, {sup 100}Mo, {sup 121}Sb, {sup 123}Sb, {sup 204}Pb, {sup 206}Pb, {sup 207}Pb, {sup 208}Pb, {sup 232}Th and {sup 238}U. The energy range covers essentially all transmutation channels other than capture. The majority of the selected elements are main constituents of normal materials of construction used in and around accelerator facilities and the library is, first and foremost, designed to be a tool for the estimation of their activation in wide-band neutron fields. This third report describes and discusses the calculational methods used for the heavy nuclei. The library itself has been described in the first report of this series and the treatment for the medium and light mass nuclei is given in the second. (author)
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.)
The low lying yrast structure of 212Po
International Nuclear Information System (INIS)
Poletti, A.R.; Dracoulis, G.D.; Byrne, A.P.; Stuchbery, A.E.
1987-07-01
The properties of states in 212 Po populated by the 208 Pb( 9 Be,αn) 212 Po reaction have been investigated. the previously proposed yrast scheme below 3MeV has been verified and eight further transitions placed in the level scheme. Mean lives of the 6 + , 8 + and (10 + ) states at 1355, 1476 and 1834 keV have been measured as 1.1(3), 24.6(3) and 0.8(2)ns respectively. Shell model calculations using effective interactions were used to interpret the observed scheme. A synthesis of all available theoretical and experimental evidence allows the 65s isomer to be identified clearly as the 18 + level arising primarily from the π(h 9/2 2 )*ν(g 9/2 i 11/2 ) configuration
The low-lying yrast structure of 212Po
International Nuclear Information System (INIS)
Poletti, A.R.; Dracoulis, G.D.; Byrne, A.P.; Stuchbery, A.E.
1987-01-01
The properties of states in 212 Po populated by the 208 Pb( 9 Be,αn) 212 Po reaction have been investigated. The previously proposed yrast scheme below ≅ 3 MeV has been verified and eight further transitions placed in the level scheme. Mean lives of the 6 + , 8 + and (10 + ) states at 1355, 1476 and 1834 keV have been measured at 1.1 (3), 24.6 (3) and 0.8 (2) ns respectively. Shell model calculations using effective interactions were used to interpret the observed scheme. A synthesis of all available theoretical and experimental evidence allows the τ m = 65 s isomer to be identified clearly as the 18 + level arising primarily from the π(h 2 9/2 ) * ν(g 9/2 i 11/2 ) configuration. (orig.)
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
Bigg, E. K.; Soubeyrand, S.; Morris, C. E.
2015-03-01
Rainfall is one of the most important aspects of climate, but the extent to which atmospheric ice nuclei (IN) influence its formation, quantity, frequency, and location is not clear. Microorganisms and other biological particles are released following rainfall and have been shown to serve as efficient IN, in turn impacting cloud and precipitation formation. Here we investigated potential long-term effects of IN on rainfall frequency and quantity. Differences in IN concentrations and rainfall after and before days of large rainfall accumulation (i.e., key days) were calculated for measurements made over the past century in southeastern and southwestern Australia. Cumulative differences in IN concentrations and daily rainfall quantity and frequency as a function of days from a key day demonstrated statistically significant increasing logarithmic trends (R2 > 0.97). Based on observations that cumulative effects of rainfall persisted for about 20 days, we calculated cumulative differences for the entire sequence of key days at each site to create a historical record of how the differences changed with time. Comparison of pre-1960 and post-1960 sequences most commonly showed smaller rainfall totals in the post-1960 sequences, particularly in regions downwind from coal-fired power stations. This led us to explore the hypothesis that the increased leaf surface populations of IN-active bacteria due to rain led to a sustained but slowly diminishing increase in atmospheric concentrations of IN that could potentially initiate or augment rainfall. This hypothesis is supported by previous research showing that leaf surface populations of the ice-nucleating bacterium Pseudomonas syringae increased by orders of magnitude after heavy rain and that microorganisms become airborne during and after rain in a forest ecosystem. At the sites studied in this work, aerosols that could have initiated rain from sources unrelated to previous rainfall events (such as power stations) would
Spectroscopy of few-particle nuclei around magic 132Sn from fission product γ-ray studies
International Nuclear Information System (INIS)
Zhang, C. T.
1998-01-01
We are studying the yrast structure of very neutron-rich nuclei around doubly magic 132 Sn by analyzing fission product γ-ray data from a 248 Cm source at Eurogam II. Yrast cascades in several few-valence-particle nuclei have been identified through γγ cross coincidences with their complementary fission partners. Results for two-valence-particle nuclei 132 Sb, 134 Te, 134 Sb and 134 Sn provide empirical nucleon-nucleon interactions which, combined with single-particle energies already known in the one-particle nuclei, are essential for shell-model analysis in this region. Findings for the N = 82 nuclei 134 Te and 135 I have now been extended to the four-proton nucleus 136 Xe. Results for the two-neutron nucleus 134 Sn and the N = 83 isotones 134 Sb, 135 Te and 135 I open up the spectroscopy of nuclei in the northeast quadrant above 132 Sn
Structure of high spin states of 76Kr and 78Kr nuclei
Indian Academy of Sciences (India)
Evolution of the shape with spin, and rotation alignment of proton as well as neutron ... by studying ground state properties of 76,78Kr by employing two sets of basis .... Figure 3. Energies of the yrast states of 76,78Kr nuclei compared with the.
The role of quasiparticles in rotating transitional nuclei
International Nuclear Information System (INIS)
Frauendorf, Stefan
1984-01-01
The yrast sequency of nuclei rotating about the symmetry axis is classified in analogy to class I and II superconductors, where the quasiparticles play the role of the quantized flux in metals. The experimental spectra show a class I behaviour. The ω-dependence of the quasiparticle excitation energy in collectively rotating nuclei is used as evidence for magnitude of the pair correlations and the occurrence of triaxial shapes. A transition from triaxial to oblate shape explains the experimental spectra and E2-transition probabilities in the N=88-90 nuclei. (author)
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
International Nuclear Information System (INIS)
EL-Falaky, E.
2007-01-01
Data on the multiplicity of the secondary produced particles in the central events from the interactions of 32S with AgBr nuclei at 118.4 GeV. A different selection criteria of the central collision in heavy ion interactions was investigated. The multiplicity distributions of the different produced shower particles (mainly pions) in the central events for each criteria was studied. The multiplicity distributions of the target fragments emitted in the central events was fitted by a Gaussian distribution. The target analysis of the experimental data shows agreement with the limiting fragmentation hypothesis
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.)
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
International Nuclear Information System (INIS)
Friedrich, J.; Voegler, N.
1982-01-01
All available information on charge distributions of even-even nuclei is analysed systematically. For medium and heavy nuclei five general features of p(r) are investigated: (i) The extension for which we discuss several different definitions. The measured extension together with experimental binding energies allows a determination of nuclear compressibility within the framework of the droplet model, the resulting value being K = 165 +- 10 MeV. (ii) The surface thickness. Here too, several definitions are discussed. A close relationship between the surface thickness and binding energies is demonstrated. (iii) The average slope in the inner part of the nucleus. A method is formulated to separate this slope from the oscillations observed. All nuclei show a positive slope of comparable size. (iv) The oscillations on p(r). They are related to an abrupt breakdown in the form factor around q = 2.25 fm -1 . This effect seems to be closely related to the fact that p(r) is built up out of single particles, details however being unimportant. (v) The high-q components of the form factor are indicative for a scattering mechanism involving pairs of nucleons. (orig.)
International Nuclear Information System (INIS)
Yamazaki, Toshimitsu.
1991-02-01
Many studies published in the past are reviewed first in relation to high-resolution spectroscopy of deeply-bound pionic atoms in heavy nuclei. The report then describes a procedure for applying the method of inverse kinematics to the case of (d, 3 He) reactions. The (d, 3 He) reaction in inverse kinematics is feasible from practical viewpoints. Thus a discussion is made of the inverse kinematics in which a heavy-ion beam ( 208 Pb for instance) with a projectile kinetic energy hits a deuteron target and ejected recoil 3 He nuclei are measured in the forward direction. The recoil momentum is calculated as a function of the Q value. Analysis shows that the recoil spectroscopy with inverse kinematics can be applied to the case of (d, 3 He) reaction, which will yield a very high mass resolution. The experimental setup for use in the first stage is then outlined, and a simple detector configuration free of magnetic field is discussed. These investigations demonstrate that the (d, 3 He) reaction in inverse kinematics provides a promising tool for obtaining high-resolution spectra of deeply-bound pionic atoms. (N.K.)
International Nuclear Information System (INIS)
Buballa, M.; Noerenberg, W.; Schaefer, B.J.; Wambach, J.
2002-01-01
The following topics were dealt with: Experimental results on ultrarelativistic heavy ion collisions, QCD thermodynamics, equilibration in relativistic heavy ion collisions, lattice QCD, space- time evolution and Hanbury-Brown-Twiss correlations, vector meson production, high-p T and small-x physics. (HSI)
Structure of the β-strength function in heavy nuclei and its influence on the β-delayed fission
International Nuclear Information System (INIS)
Wene, C.O.; Isosimow, I.N.; Naumow, Y.W.; Klapdor, H.V.
1978-01-01
The shape of the beta strength function Ssub(β) for neutron-rich nuclei is discussed. The structure of Ssub(β) is calculated microscopically for the GT-β-decay of 236 , 238 Pa and is shown to be decisive for the probability for β-delayed fission. (orig.) [de
Very high-spin states in nuclei
International Nuclear Information System (INIS)
Diamond, R.M.
1977-03-01
The continuum γ-ray spectrum following emission in a (HI,xn) reaction consists of a high-energy tail, the statistical cascade, and a lower-energy bump, the yrast cascade, which contains most of the intensity and consists mostly of stretched E2 transitions. Thus, a good approximation to the average angular momentum carried by the γ-ray is 2Nsub(γ). Under favourable conditions, effective moments of inertia can be deduced for states up to the top of the γ-ray cascade. The maximum angular momentum in the cascades is probably limited by α-emission for nuclei with A 150. (Author)
Grosse, Eckart; Massarczyk, Ralph
2014-01-01
Cross sections for neutron capture in the range of unresolved resonances are predicted simultaneously to level distances at the neutron threshold for more than 100 spin-0 target nuclei with A >70. Assuming triaxiality in nearly all these nuclei a combined parameterization for both, level density and photon strength is presented. The strength functions used are based on a global fit to IVGDR shapes by the sum of three Lorentzians adding up to the TRK sum rule and theory-based predictions for the A-dependence of pole energies and spreading widths. For the small spins reached by capture level densities are well described by only one free global parameter; a significant collective enhancement due to the deviation from axial symmetry is observed. Reliable predictions for compound nuclear reactions also outside the valley of stability as expected from the derived global parameterization are important for nuclear astrophysics and for the transmutation of nuclear waste.
High-spin excitations of atomic nuclei
International Nuclear Information System (INIS)
Xu Furong; National Laboratory of Heavy Ion Physics, Lanzhou; Chinese Academy of Sciences, Beijing
2004-01-01
The authors used the cranking shell model to investigate the high-spin motions and structures of atomic nuclei. The authors focus the collective rotations of the A∼50, 80 and 110 nuclei. The A∼50 calculations show complicated g spectroscopy, which can have significant vibration effects. The A≅80 N≅Z nuclei show rich shape coexistence with prolate and oblate rotational bands. The A≅110 nuclei near the r-process path can have well-deformed oblate shapes that become yrast and more stable with increasing rotational frequency. As another important investigation, the authors used the configuration-constrained adiabatic method to calculate the multi-quasiparticle high-K states in the A∼130, 180 and superheavy regions. The calculations show significant shape polarizations due to quasi-particle excitations for soft nuclei, which should be considered in the investigations of high-K states. The authors predicted some important high-K isomers, e.g., the 8 - isomers in the unstable nuclei of 140 Dy and 188 Pb, which have been confirmed in experiments. In superheavy nuclei, our calculations show systematic existence of high-K states. The high-K excitations can increase the productions of synthesis and the survival probabilities of superheavy nuclei. (authors)
Isomeric and high-spin states of 94Tc and the search for yrast isomers near Napprox.50
International Nuclear Information System (INIS)
Lee, I.Y.; Johnson, N.R.; McGowan, F.K.; Young, G.R.; Guidry, M.W.; Yates, S.W.
1981-01-01
A search for isomers in the Napprox.50 region has produced no evidence of high-spin yrast isomerism. A new 4.5-ns low-multiplicity isomer has been identified and assigned to 94 Tc, while the yrast sequence of 94 Tc has been established to more than 5 MeV in excitation energy
International Nuclear Information System (INIS)
Sarswat, S.P.; Bharti, Arun; Khosa, S.K.
1996-01-01
The yrast spectra has been obtained in the variation-after-projection framework using pairing-plus-quadrupole- quadrupole model for the two body interaction. Besides the low-lying yrast spectra, the calculated values of intrinsic quadrupole moments of some of the barium isotopes i.e. 124-134 Ba are presented
General Relativistic Mean Field Theory for rotating nuclei
Energy Technology Data Exchange (ETDEWEB)
Madokoro, Hideki [Kyushu Univ., Fukuoka (Japan). Dept. of Physics; Matsuzaki, Masayuki
1998-03-01
The {sigma}-{omega} model Lagrangian is generalized to an accelerated frame by using the technique of general relativity which is known as tetrad formalism. We apply this model to the description of rotating nuclei within the mean field approximation, which we call General Relativistic Mean Field Theory (GRMFT) for rotating nuclei. The resulting equations of motion coincide with those of Munich group whose formulation was not based on the general relativistic transformation property of the spinor fields. Some numerical results are shown for the yrast states of the Mg isotopes and the superdeformed rotational bands in the A {approx} 60 mass region. (author)
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
Energy Technology Data Exchange (ETDEWEB)
Gupta, Anuradha; Singh, Suram; Bharti, Arun [University of Jammu, Department of Physics and Electronics, Jammu (India); Khosa, S.K. [Central University of Jammu, Department of Physics and Astronomical Sciences, Jammu (India); Bhat, G.H.; Sheikh, J.A. [University of Kashmir, Department of Physics, Srinagar (India)
2017-01-15
By employing a systematically parametrized Hamiltonian and the best fit of the various input parameters, high-spin yrast energy states for an isotopic chain of odd mass {sup 59-69}Cu nuclei have been investigated by using a novel computational quantum mechanical framework-projected shell model. Comparison of calculations and experiments yields good agreement. The present study of various intriguing nuclear structure properties along the yrast lines in these odd proton isotopes reflects some interesting informative nuclear physics results. The calculations successfully describe the formation of the yrast level structures from multi-quasi-particle configurations based on πf x νg bands for {sup 59-69}Cu isotopes. The present calculations indicate the evolution of the nuclear structure near the magic nuclei, Ni, and also provide an indication of coexistence of both, collective as well as single-particle, levels for {sup 69}Cu nucleus at N=40. (orig.)
High-spin structure of yrast-band in Kr
Indian Academy of Sciences (India)
320(70) fs was obtained from the present data at 75. ° for the 24. + level. Zeigler's stopping powers have been used for the calculation of the energy loss parameters of the recoiling nuclei. The experimental data along with the theoretical fits for the lifetimes measured can be seen in figure 1. The present lifetime values up to ...
Microscopic insight in the study of yrast bands in selenium isotopes
Indian Academy of Sciences (India)
the rotational-like energy spacings of the yrast states with I≥6. ... even–even selenium isotopes, the study of structure of high spin states through mea- ... calculations with this model can achieve a comparable quality to the large-scale ... model in that the PSM uses the angular momentum projected states as the basis.
International Nuclear Information System (INIS)
Mustafa, M.G.; Kumar, K.
1975-06-01
The two-center shell model for fission is extended to include the effects of nuclear rotation or angular momentum J. The principle of minimization of total nuclear energy with respect to a constraint on J leads to an effective potential energy which depends on J as well as moment of inertia. This effective potential energy is minimized with respect to nuclear shape variables, neutron pairing energy gap, and proton pairing energy gap for each J value. The resulting potential minima, fission barriers, and moments of inertia are quite sensitive to J. Results are given for 208 82 Pb, 240 94 Pu, and for a super-heavy nucleus, 298 114 X. Microscopic calculations of the critical angular momentum (at which the fission barrier vanishes) are compared with the rotating liquid drop calculations of Cohen, Plasil, and Swiatecki. The influence of these results on the possibility of fusion in heavy-ion reactions is discussed. (5 figures, 6 tables) (U.S.)
International Nuclear Information System (INIS)
Djalali, C.; Marty, N.; Morlet, M.
1982-01-01
In a series of seventeen nuclei ranging from 51 V to 140 Ca, broad resonance structures are observed at energies between 8 and 10 MeV, nearly mass independent. These resonances have very forward peaked angular distributions which imply that they are populated by an angular momentum transfer of zero. This together with the observed excitation energies suggests an M1 character for these resonances. In 51 V, 58 Ni, 60 Ni, 62 Ni, a sharp peak located at an excitation energy above the threshold for neutron emission is interpreted as a part of the T 0+1 component of the M1 resonances. Cross-sections are given for all the M1 resonances. For 58 Ni, 90 Zr, 92 Mo, 120 Sn and 140 Ca, an ''attenuation'' factor for the cross-sections is extracted in a OWIA calculation assuming simple shell model structures for these resonances
Shell model for warm rotating nuclei
Energy Technology Data Exchange (ETDEWEB)
Matsuo, M.; Yoshida, K. [Kyoto Univ. (Japan); Dossing, T. [Univ. of Copenhagen (Denmark)] [and others
1996-12-31
Utilizing a shell model which combines the cranked Nilsson mean-field and the residual surface and volume delta two-body forces, the authors discuss the onset of rotational damping in normal- and super-deformed nuclei. Calculation for a typical normal deformed nucleus {sup 168}Yb indicates that the rotational damping sets in at around 0.8 MeV above the yrast line, and about 30 rotational bands of various length exists at a given rotational frequency, in overall agreement with experimental findings. It is predicted that the onset of rotational damping changes significantly in different superdeformed nuclei due to the variety of the shell gaps and single-particle orbits associated with the superdeformed mean-field.
International Nuclear Information System (INIS)
Sundaralingam, N.
1993-01-01
We study multiple muon events (muon bundles) recorded underground at a depth of 2090 mwe. To penetrate to this depth, the muons must have energies above 0.8 TeV at the Earth's surface; the primary cosmic ray nuclei which give rise to the observed muon bundles have energies at incidence upon the upper atmosphere of 10 to 10 5 TeV. The events are detected using the Soudan 2 experiment's fine grained tracking calorimeter which is surrounded by a 14 m x10 m x 31 m proportional tube array (the ''active shield''). Muon bundles which have at least one muon traversing the calorimeter, are reconstructed using tracks in the calorimeter together with hit patterns in the proportional tube shield. All ionization pulses are required to be coincident within 3 microseconds. A goal of this study is to investigate the relative nuclear abundances in the primary cosmic radiation around the ''knee'' region (10 3 - 10 4 TeV) of the incident energy spectrum. Four models for the nuclear composition of cosmic rays are considered: The Linsley model, the Constant Mass Composition model (CMC), the Maryland model and the Proton-poor model. A Monte Carlo which incorporates one model at a time is used to simulate events which are then reconstructed using the same computer algorithms that are used for the data. Identical cuts and selections are applied to the data and to the simulated events
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
Second proton and neutron alignments in the doubly-odd nuclei 154,156Tb
International Nuclear Information System (INIS)
Hartley, D.J.; Allen, J.L.; Brown, T.B.; Kondev, F.G.; Pfohl, J.; Riley, M.A.; Fischer, S.M.; Janssens, R.V.; Nisius, D.T.; Fallon, P.; Ma, W.C.; Simpson, J.
1999-01-01
High-spin states in the doubly-odd nuclei 154,156 Tb have been populated in two separate experiments using the 36 S+ 124 Sn reaction at different beam energies (160 and 175 MeV). The yrast structures of both nuclei were extended to much higher spin (I≤48ℎ) than previously known and several quasiparticle alignments have been identified. These include the second neutron alignment and a clear delineation of the second proton crossing in 156 Tb. Systematics of these crossings for odd-Z nuclei and comparisons with results of cranked shell model calculations are discussed. thinsp copyright 1999 The American Physical Society
Energy Technology Data Exchange (ETDEWEB)
Akram, W.; Schönbächler, M. [School of Earth, Atmospheric and Environmental Sciences, The University of Manchester, Oxford Road, Manchester, M13 9PL (United Kingdom); Sprung, P. [Institut für Planetologie, Universität Münster, Wilhelm-Klemm-Strasse 10, D-48149 Münster (Germany); Vogel, N. [Institute for Geochemistry and Petrology, ETH, Clausiusstrasse 25, 8092 Zürich (Switzerland)
2013-11-10
Recent work based on analyses of meteorite and terrestrial whole-rock samples showed that the r- and s- process isotopes of Hf were homogeneously distributed throughout the inner solar system. We report new Hf isotope data for Calcium-Aluminum-rich inclusions (CAIs) of the CV3 carbonaceous chondrite Allende, and novel high-precision Zr isotope data for these CAIs and three carbonaceous chondrites (CM, CO, CK). Our Zr data reveal enrichments in the neutron-rich isotope {sup 96}Zr (≤1ε in {sup 96}Zr/{sup 90}Zr) for bulk chondrites and CAIs (∼2ε). Potential isotope effects due to incomplete sample dissolution, galactic and cosmic ray spallation, and the nuclear field shift are assessed and excluded, leading to the conclusion that the {sup 96}Zr isotope variations are of nucleosynthetic origin. The {sup 96}Zr enrichments are coupled with {sup 50}Ti excesses suggesting that both nuclides were produced in the same astrophysical environment. The same CAIs also exhibit deficits in r-process Hf isotopes, which provides strong evidence for a decoupling between the nucleosynthetic processes that produce the light (A ≤ 130) and heavy (A > 130) neutron-rich isotopes. We propose that the light neutron-capture isotopes largely formed in Type II supernovae (SNeII) with higher mass progenitors than the supernovae that produced the heavy r-process isotopes. In the context of our model, the light isotopes (e.g. {sup 96}Zr) are predominantly synthesized via charged-particle reactions in a high entropy wind environment, in which Hf isotopes are not produced. Collectively, our data indicates that CAIs sampled an excess of materials produced in a normal mass (12-25 M{sub ☉}) SNII.
Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Alekseev, I.; Aparin, A.; Arkhipkin, D.; Aschenauer, E. C.; Attri, A.; Averichev, G. S.; Bai, X.; Bairathi, V.; Bellwied, R.; Bhasin, A.; Bhati, A. K.; Bhattarai, P.; Bielcik, J.; Bielcikova, J.; Bland, L. C.; Bordyuzhin, I. G.; Bouchet, J.; Brandenburg, J. D.; Brandin, A. V.; Bunzarov, I.; Butterworth, J.; Caines, H.; Calderón de la Barca Sánchez, M.; Campbell, J. M.; Cebra, D.; Chakaberia, I.; Chaloupka, P.; Chang, Z.; Chatterjee, A.; Chattopadhyay, S.; Chen, J. H.; Chen, X.; Cheng, J.; Cherney, M.; Christie, W.; Contin, G.; Crawford, H. J.; Das, S.; De Silva, L. C.; Debbe, R. R.; Dedovich, T. G.; Deng, J.; Derevschikov, A. A.; di Ruzza, B.; Didenko, L.; Dilks, C.; Dong, X.; Drachenberg, J. L.; Draper, J. E.; Du, C. M.; Dunkelberger, L. E.; Dunlop, J. C.; Efimov, L. G.; Engelage, J.; Eppley, G.; Esha, R.; Evdokimov, O.; Eyser, O.; Fatemi, R.; Fazio, S.; Federic, P.; Fedorisin, J.; Feng, Z.; Filip, P.; Fisyak, Y.; Flores, C. E.; Fulek, L.; Gagliardi, C. A.; Garand, D.; Geurts, F.; Gibson, A.; Girard, M.; Greiner, L.; Grosnick, D.; Gunarathne, D. S.; Guo, Y.; Gupta, S.; Gupta, A.; Guryn, W.; Hamad, A. I.; Hamed, A.; Haque, R.; Harris, J. W.; He, L.; Heppelmann, S.; Heppelmann, S.; Hirsch, A.; Hoffmann, G. W.; Horvat, S.; Huang, T.; Huang, X.; Huang, B.; Huang, H. Z.; Huck, P.; Humanic, T. J.; Igo, G.; Jacobs, W. W.; Jang, H.; Jentsch, A.; Jia, J.; Jiang, K.; Judd, E. G.; Kabana, S.; Kalinkin, D.; Kang, K.; Kauder, K.; Ke, H. W.; Keane, D.; Kechechyan, A.; Khan, Z. H.; Kikoła, D. P.; Kisel, I.; Kisiel, A.; Kochenda, L.; Koetke, D. D.; Kosarzewski, L. K.; Kraishan, A. F.; Kravtsov, P.; Krueger, K.; Kumar, L.; Lamont, M. A. C.; Landgraf, J. M.; Landry, K. D.; Lauret, J.; Lebedev, A.; Lednicky, R.; Lee, J. H.; Li, X.; Li, C.; Li, X.; Li, Y.; Li, W.; Lin, T.; Lisa, M. A.; Liu, F.; Ljubicic, T.; Llope, W. J.; Lomnitz, M.; Longacre, R. S.; Luo, X.; Ma, R.; Ma, G. L.; Ma, Y. G.; Ma, L.; Magdy, N.; Majka, R.; Manion, A.; Margetis, S.; Markert, C.; Matis, H. S.; McDonald, D.; McKinzie, S.; Meehan, K.; Mei, J. C.; Minaev, N. G.; Mioduszewski, S.; Mishra, D.; Mohanty, B.; Mondal, M. M.; Morozov, D. A.; Mustafa, M. K.; Nandi, B. K.; Nasim, Md.; Nayak, T. K.; Nigmatkulov, G.; Niida, T.; Nogach, L. V.; Noh, S. Y.; Novak, J.; Nurushev, S. B.; Odyniec, G.; Ogawa, A.; Oh, K.; Okorokov, V. A.; Olvitt, D.; Page, B. S.; Pak, R.; Pan, Y. X.; Pandit, Y.; Panebratsev, Y.; Pawlik, B.; Pei, H.; Perkins, C.; Pile, P.; Pluta, J.; Poniatowska, K.; Porter, J.; Posik, M.; Poskanzer, A. M.; Pruthi, N. K.; Putschke, J.; Qiu, H.; Quintero, A.; Ramachandran, S.; Raniwala, R.; Raniwala, S.; Ray, R. L.; Ritter, H. G.; Roberts, J. B.; Rogachevskiy, O. V.; Romero, J. L.; Ruan, L.; Rusnak, J.; Rusnakova, O.; Sahoo, N. R.; Sahu, P. K.; Sakrejda, I.; Salur, S.; Sandweiss, J.; Sarkar, A.; Schambach, J.; Scharenberg, R. P.; Schmah, A. M.; Schmidke, W. B.; Schmitz, N.; Seger, J.; Seyboth, P.; Shah, N.; Shahaliev, E.; Shanmuganathan, P. V.; Shao, M.; Sharma, M. K.; Sharma, B.; Shen, W. Q.; Shi, Z.; Shi, S. S.; Shou, Q. Y.; Sichtermann, E. P.; Sikora, R.; Simko, M.; Singha, S.; Skoby, M. J.; Smirnov, N.; Smirnov, D.; Solyst, W.; Song, L.; Sorensen, P.; Spinka, H. M.; Srivastava, B.; Stanislaus, T. D. S.; Stepanov, M.; Stock, R.; Strikhanov, M.; Stringfellow, B.; Sumbera, M.; Summa, B.; Sun, X. M.; Sun, Z.; Sun, Y.; Surrow, B.; Svirida, D. N.; Tang, Z.; Tang, A. H.; Tarnowsky, T.; Tawfik, A.; Thäder, J.; Thomas, J. H.; Timmins, A. R.; Tlusty, D.; Todoroki, T.; Tokarev, M.; Trentalange, S.; Tribble, R. E.; Tribedy, P.; Tripathy, S. K.; Tsai, O. D.; Ullrich, T.; Underwood, D. G.; Upsal, I.; Van Buren, G.; van Nieuwenhuizen, G.; Vandenbroucke, M.; Varma, R.; Vasiliev, A. N.; Vertesi, R.; Videbæk, F.; Vokal, S.; Voloshin, S. A.; Vossen, A.; Wang, Y.; Wang, G.; Wang, J. S.; Wang, H.; Wang, Y.; Wang, F.; Webb, G.; Webb, J. C.; Wen, L.; Westfall, G. D.; Wieman, H.; Wissink, S. W.; Witt, R.; Wu, Y.; Xiao, Z. G.; Xie, W.; Xie, G.; Xin, K.; Xu, H.; Xu, Z.; Xu, J.; Xu, Y. F.; Xu, Q. H.; Xu, N.; Yang, Y.; Yang, S.; Yang, C.; Yang, Y.; Yang, Y.; Yang, Q.; Ye, Z.; Ye, Z.; Yepes, P.; Yi, L.; Yip, K.; Yoo, I.-K.; Yu, N.; Zbroszczyk, H.; Zha, W.; Zhang, J.; Zhang, Y.; Zhang, X. P.; Zhang, Z.; Zhang, J. B.; Zhang, S.; Zhang, S.; Zhang, J.; Zhao, J.; Zhong, C.; Zhou, L.; Zhu, X.; Zoulkarneeva, Y.; Zyzak, M.; STAR Collaboration
2016-09-01
We present measurements of second-order azimuthal anisotropy (v2) at midrapidity (|y |<1.0 ) for light nuclei d ,t ,3He (for √{sN N}=200 , 62.4, 39, 27, 19.6, 11.5, and 7.7 GeV) and antinuclei d ¯ (√{sN N}=200 , 62.4, 39, 27, and 19.6 GeV) and ¯3He (√{sN N}=200 GeV) in the STAR (Solenoidal Tracker at RHIC) experiment. The v2 for these light nuclei produced in heavy-ion collisions is compared with those for p and p ¯. We observe mass ordering in nuclei v2(pT) at low transverse momenta (pT<2.0 GeV/c ). We also find a centrality dependence of v2 for d and d ¯. The magnitude of v2 for t and 3He agree within statistical errors. Light-nuclei v2 are compared with predictions from a blast-wave model. Atomic mass number (A ) scaling of light-nuclei v2(pT) seems to hold for pT/A <1.5 GeV /c . Results on light-nuclei v2 from a transport-plus-coalescence model are consistent with the experimental measurements.
Energy Technology Data Exchange (ETDEWEB)
Rosenbusch, Marco [Ernst-Moritz-Arndt-Universitaet, Institut fuer Physik, 17487 Greifswald (Germany); Collaboration: ISOLTRAP-Collaboration
2013-07-01
The mass is a unique property of an atomic nucleus reflecting its binding energy and thus the sum of all interactions at work. Precise measurements of nuclear masses especially of short-lived exotic nuclides provide important input for nuclear structure, nuclear astrophysics, tests of the Standard Model, and weak interaction studies. The Penning-trap mass spectrometer ISOLTRAP at the on-line isotope separator ISOLDE/CERN has been set up for precision mass measurements and continuously improved for accessing more exotic nuclides. The mass uncertainty is typically δm / m=10{sup -8} and the accessible half-life has been reduced to about 50 ms. In this contribution, the results of a measurement campaign of neutron-rich francium and radium isotopes will be presented, i.e. the masses of the isotopic chain of {sup 224-233}Fr and {sup 233,234}Ra, one of the most neutron-rich ensemble obtainable at ISOL facilities. The mass {sup 234}Ra denotes the heaviest mass ever measured with ISOLTRAP. Experimental data in the neutron-rich, heavy mass region is of great interest for studies of structural evolution far from stability, especially because the knowledge from nuclear mass models is scarce. The impact of the new data on the physics in this mass region as well as recent technical developments of ISOLTRAP are discussed.
International Nuclear Information System (INIS)
Matuoka, Paula Fernanda Toledo
2016-01-01
In the present work, intermediate- and high-energy nuclear reactions involving heavy nuclei and protons were studied with the Monte Carlo CRISP (Rio - Ilheus - Sao Paulo Collaboration) model. The most relevant nuclear processes studied were intranuclear cascade and fission-evaporation competition. Preliminary studies showed fair agreement between CRISP model calculation and experimental data of multiplicity of evaporated neutrons (E 20 MeV) were emitted mostly in the intranuclear cascade stage, while evaporation presented larger neutron multiplicity. Fission cross section of 209 mb and spallation cross section of 1788 mb were calculated { both in agreement with experimental data. The fission process resulted in a symmetric mass distribution. Another Monte Carlo code, MCNP, was used for radiation transport in order to understand the role of a spallation neutron source in a ADS (Accelerator Driven System) nuclear reactor. Initially, a PWR reactor was simulated to study the isotopic compositions in spent nuclear fuel. As a rst attempt, a spallation neutron source was adapted to an industrial size nuclear reactor. The results showed no evidence of incineration of transuranic elements and modifications were suggested. (author)
International Nuclear Information System (INIS)
Bohle, D.
1985-01-01
By inelastic electron scattering with high energy resolution a new magnetic dipole mode in heavy, deformed nuclei could be detected. For this the nuclei 154 Sm, 156 Gd, 158 Gd, 164 Dy, 168 Er, and 174 Yb were studied at the Darmstadt electron linear accelerator (DALINAC) at small momentum transfer q ≤ 0.6 fm -1 and low excitation energies. A collective magnetic dipole excitation could be discovered in all nuclei at an excitation energy of E x ≅ 66 δA -1/3 MeV whereby δ means the mass deformation. The transition strength extends in the mean to B(M1)↑ ≅ 1.3 μ N 2 . A systematic study of the nucleus 156 Gd yielded hints to a strong fragmentation of the magnetic dipole strength. A comparison of electron scattering, proton scattering, and nuclear resonance fluorescence experiments shows that the new mode is a pure orbital mode. (orig./HSI) [de
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
Non-yrast states and shape co-existence in 172Os
International Nuclear Information System (INIS)
Davidson, P.M.; Dracoulis, G.D.; Kibedi, T.; Byrne, A.P.; Anderssen, S.S.; Baxter, A.M.; Fabricius, B.; Lane, G.J.; Stuchbery, A.E.
1994-01-01
Previous studies of 172 Os noted an anomaly in the behaviour of the moment of inertia of the yrast band at low spin. A phenomenological model of shape coexistence based on interacting rotational bands was proposed to explain this anomaly and this model predicted low-lying non-yrast states. In order to test these predictions, the β-decay of 172 Ir has been used to populate 172 Os. Excited states have been observed and classified into positive-parity ''quasi-β'' and ''quasi-γ'' bands and a negative-parity band. The energies of the quasi-β band states are seen to be in general agreement with the predictions of the phenomenological model and the model is refined to take into account the new data. The bands involved are determined to have significantly different moments of inertia. (orig.)
Yrast spectroscopy in the neutron-deficient nucleus 169Os
International Nuclear Information System (INIS)
Joss, D.T.; Simpson, J.; Appelbe, D.E.; Warner, D.D.; Page, R.D.; King, S.L.; Amzal, N.; Cullen, D.M.; Greenlees, P.T.; Keenan, A.; Baeck, T.; Cederwall, B.; Wyss, R.; Bentley, M.A.; Williams, S.J.; Cocks, J.F.C.; Helariutta, K.; Jones, P.M.; Julin, R.; Juutinen, S.
2002-01-01
Excited states in the neutron-deficient isotope 169 Os have been identified for the first time in an experiment using the Jurosphere γ-ray spectrometer in conjunction with the Ritu gas-filled recoil separator. The problems associated with identifying neutron-deficient isotopes produced with low fusion cross sections against a high background of competing channels, including fission, have been overcome by using the recoil-decay tagging technique. The band structures observed in 169 Os are interpreted in the context of the systematics of neighboring nuclei and the predictions of cranked Woods-Saxon calculations. The systematics of the second (i 13/2 ) 2 neutron alignment in this region are discussed
High spin states in 63Cu. 17/2+ isomeric yrast state
International Nuclear Information System (INIS)
Tsan Ung Chan; Bruandet, J.F.; Dauchy, A.; Giorni, A.; Glasser, F.; Morand, C.; Chambon, B.; Drain, D.
1979-01-01
The 63 Cu nucleus has been studied via the reaction 61 Ni(α, pnγ), using different in beam γ spectroscopy techniques. An isomeric high-spin Yrast state 17/2 + (tau = 6.1 +- 0.6ns) is located at 4498 keV. The gsub(9/2) shell must be involved to explain positive high-spin states established in this work [fr
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)
Decay out of the yrast and excited highly-deformed bands in the even-even nucleus {sup 134}Nd
Energy Technology Data Exchange (ETDEWEB)
Petrache, C.M.; Bazzacco, D.; Lunardi, S. [Sezione di Padova (Italy)] [and others
1996-12-31
The resolving power achieved by the new generation of {gamma}-ray detector arrays allows now to observe transitions with intensities of the order of {approximately}10{sup {minus}3} of the population of the final residual nucleus, making therefore feasible the study of the very weakly populated excited bands built on the superdeformed (SD) minimum or of the decay out of the SD bands. As a matter of fact, numerous excited SD bands have been observed in the different regions of superdeformation, which led to a deeper understanding of the single-particle excitation in the second minimum. The first experimental breakthrough in the study of the decay out process has been achieved in the odd-even {sup 133,135}Nd nuclei of the A=130 mass region. There, the observation of the discrete linking transitions has been favored by the relatively higher intensity of the highly-deformed (HD) bands ({approximately}10%), as well as by the small excitation energy with respect to the yrast line in the decay-out region ({approximately}1 MeV). No discrete linking transitions have been so far observed in the A=80, 150 mass regions. The present results suggest that the decay out of the HD bands in {sup 134}Nd is triggered by the crossing with the N=4 [402]5/2{sup +} Nilsson orbital, that has a smaller deformation than the corresponding N=6 intruder configuration. The crossing favours the mixing with the ND rotational bands strongly enhancing the decay-out process and weakening the in-band transition strength. The HD band becomes fragmented and looses part of its character. The intensity of the decay-out transitions increases when the spin of the HD state decreases, indicating enhanced ND amplitude in the wavefunction when going down the band. Lifetime measurements of the HD bands are crucial to further elucidate the decay-out process.
Particle-hole excitations in N=50 nuclei
International Nuclear Information System (INIS)
Johnstone, I.P.; Skouras, L.D.
1997-01-01
Energy levels in N=50 nuclei are calculated allowing single-particle excitations from the p 1/2 and g 9/2 shells into the d 5/2 , s 1/2 , d 3/2 , and g 7/2 shells. Important parts of the interaction are determined by least-squares fits to known levels. Agreement with experiment is very good. The high-spin particle-hole states appear to be mainly yrast levels in mass 93 and higher, but are not in 90 Zr. copyright 1997 The American Physical Society
Studies of high-K isomers in hafnium nuclei
International Nuclear Information System (INIS)
Sletten, G.; Gjoerup, N.L.
1991-01-01
K-isomeric states built on high-Ω Nilsson orbitals from deformation-aligned high-j levels near the Fermi surface are found to cluster in the neutron rich Hf, W and Os nuclei. It has been shown that some of the high seniority states of this type have decay properties that indicate strong mixing of configurations and that in Osmium nuclei γ-softness cause strong deviations from the well established K-selection rule. Also in the Hafnium nuclei is the expected forbiddenness in isomeric decays an order of magnitude smaller than expected from the K-selection rule. A new 9 quasiparticle isomer has been discovered in 175 Hf at I=57/2. This isomer has the anomalous decay as the dominant mode. Other lower seniority states are also identified. At spin 35/2 and 45/2 the deformation aligned states become yrast, but the structure of the yrast line to even higher spins is not yet understood. (author)
High spin rotations of nuclei with the harmonic oscillator potential
International Nuclear Information System (INIS)
Cerkaski, M.; Szymanski, Z.
1978-01-01
Calculations of the nuclear properties at high angular momentum have been performed recently. They are based on the liquid drop model of a nucleus and/or on the assumption of the single particle shell structure of the nucleonic motion. The calculations are usually complicated and involve long computer codes. In this article we shall discuss general trends in fast rotating nuclei in the approximation of the harmonic oscillator potential. We shall see that using the Bohr Mottelson simplified version of the rigorous solution of Valatin one can perform a rather simple analysis of the rotational bands, structure of the yrast line, moments of inertia etc. in the rotating nucleus. While the precision fit to experimental data in actual nuclei is not the purpose of this paper, one can still hope to reach some general understanding within the model of the simple relations resulting in nuclei at high spin. (author)
A pocketful of tin isomers from heavy-ion collisions
International Nuclear Information System (INIS)
Daly, P.J.; Broda, R.; Fornal, B.; Mayer, R.H.; Nisius, D.; Bearden, I.; Benet, P.; Grabowski, Z.W.; Lauritsen, T.; Carpenter, M.; Janssens, R.V.F.; Khoo, T.L.; Liang, Y.; Lunardi, S.; Blomqvist, J.
1992-01-01
Reaction products of 122,124 Sn + 76 Ge( 8O Se) collisions 10--15% above the barrier have been studied by γ-ray spectroscopy, and new yrast isomers in 119--124 Sn isotopes have been identified and characterized. B(E2) values determined for (νh 11/2 ) n 10 + → 8 + transitions in even-A Sn nuclei pinpoint half-filling of the νh 11/2 subshell close to N = 73. In odd-A Sn isotopes, 19/2 + isomers with 1--10 μs half-lives occur systematically, and higher-lying (νh ll/2 ) n v=3 27/2 - isomers in 119 Sn and 121 Sn have also been identified. These deep inelastic excitation processes were found to populate a large number of neutron-rich nuclei strongly enough for yrast spectroscopy studies
Very high-spin states in nuclei
International Nuclear Information System (INIS)
Diamond, R.M.
1977-01-01
The continuum γ-ray spectrum following neutron emission in a (HI,xn) reaction consists of a high-energy tail, the statistical cascade, and a lower-energy bump, the yrast cascade, which contains most of the intensity and consists mostly of stretched E2 transitions. Thus, a good approximation to the average angular momentum carried by the γ-rays is 2N/sub γ/-bar. Under favourable conditions, effective moments of inertia can be deduced for states up to the top of the γ-ray cascade. The maximum angular momentum in the cascades is probably limited by α-emission for nuclei with A 150. 17 figures
High and highest spin states in nuclei
International Nuclear Information System (INIS)
Ploszajczak, M.
1977-06-01
A study of the following phenomena in rotating nuclei is presented, namely: 1) the destruction of the pair-correlation between the protons and the neutrons as well as decoupling and orientation of the particles along the rotation axis; 2) the formation of a nucleus with axial symmetry rotating around the symmetry axis, caused by the strong centrifugal and Coriolis forces; 3) the shell effects at low angular momentum, which led in some Pb, Hg and Pt isotopes to the formation of a prolate nucleus, rotating around the symmetry axis; 4) the formation of longliving states at very high angular momenta ('Yrast-traps'). At low angular momenta the nucleus is described by the Cranking-Hartree-Fock-Bogolyubov theory (CHFB) with the pair-(P), quadrupole-(QQ) and hexade coupole force (HH) as residual interaction. (orig.) [de
Effects of successive critical distances in heavy ion fusion reactions
International Nuclear Information System (INIS)
Lee, S.M.; Nakagawa, T.; Matsuse, T.
1984-01-01
The concept of Successive Critical Distances is presented. It appears that whether the fusion cross section is limited by compound nucleus or entrance channel properties depends on the degree of asymmetry of the fusing nuclei. Only in the near to symmetry case does the Statistical Yrast Line emerge as a limiting factor. Otherwise, the critical angular momentum for fusion is restricted by a critical distance
Gamma-ray spectroscopy of neutron-rich products of heavy-ion collisions
Energy Technology Data Exchange (ETDEWEB)
Carpenter, M.P.; Janssens, R.V.F.; Ahmad, I. [and others
1995-08-01
Thick-target {gamma}{gamma} coincidence techniques are being used to explore the spectroscopy of otherwise hard-to-reach neutron-rich products of deep-inelastic heavy ion reactions. Extensive {gamma}{gamma} coincidence measurements were performed at ATLAS using pulsed beams of {sup 80}Se, {sup 136}Xe, and {sup 238}U on lead-backed {sup 122,124}Sn targets with energies 10-15% above the Coulomb barrier. Gamma-ray coincidence intensities were used to map out yield distributions with A and Z for even-even product nuclei around the target and around the projectile. The main features of the yield patterns are understandable in terms of N/Z equilibration. We had the most success in studying the decays of yrast isomers. Thus far, more than thirty new {mu}s isomers in the Z = 50 region were found and characterized. Making isotopic assignments for previously unknown {gamma}-ray cascades proves to be one of the biggest problems. Our assignments were based (a) on rare overlaps with radioactivity data, (b) on the relative yields with different beams, and (c) on observed cross-coincidences between {gamma} rays from light and heavy reaction partners. However, the primary products of deep inelastic collisions often are sufficiently excited for subsequent neutron evaporation, so {gamma}{gamma} cross-coincidence results require careful interpretation.
Isomeric and high-spin states of 94Tc and the search for yrast isomers near N~50
Lee, I. Y.; Johnson, N. R.; McGowan, F. K.; Young, G. R.; Guidry, M. W.; Yates, S. W.
1981-07-01
A search for isomers in the N~50 region has produced no evidence of high-spin yrast isomerism. A new 4.5-ns low-multiplicity isomer has been identified and assigned to 94Tc, while the yrast sequence of 94Tc has been established to more than 5 MeV in excitation energy. [NUCLEAR REACTIONS 76Ge, 78Se(20Ne,xnypγ), E=80.9 MeV, 89Y, 93Nb(10B,xnypγ), E=52.0,58.4,62.8 MeV; measured Eγ, Iγ, γ-γ prompt and delayed coin, γ-X coin; deduced levels, t12 of 94Tc isomer, yrast states.
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.)
First observation of yrast band in odd-odd 162Lu
International Nuclear Information System (INIS)
Zhang, Y.H.; Yuan, G.J.; Liu, X.A.
1996-01-01
High spin states of the odd-odd 162 Lu nucleus have been studied via 147 Sm( 19 F, 4nγ) 162 Lu reaction at 95MeV beam energy. Level scheme for yrast band based on π[h 11/2 ] υ[i 13/2 ] quasiparticle configuration was established up to I π =(23 - ) for the first time. This band shows the signature inversion in energy before backbending generally appeared in this mass region. It is stressed that the signature splitting in 162 Lu is larger than that in the 160 Tm nucleus. (orig.)
Theisen, Christophe
2017-11-01
Several facilities or apparatus for the synthesis and spectroscopy of the Super-Heavy Nuclei (SHN) are presently under construction in the world, which reflect the large interest for this region of extreme mass and charge, but also for the need of even more advanced research infrastructures. Among this new generation, the GANIL/SPIRAL2 facility in Caen, France, will soon deliver very high intense ion beams of several tens of particle μA. The Super Separator Spectrometer S3 has been designed to exploit these new beams for the study of SHN after separation. It will provide the needed beam rejection, mass selection and full arsenal of state-of-the art detection setups. Still at GANIL, the AGATA new generation gamma-ray tracking array is being operated. The VAMOS high acceptance spectrometer is being upgraded as a gas-filled separator. Its coupling with AGATA will lower the spectroscopic limits for the prompt gamma-ray studies of heavy and super-heavy nuclei. In this proceeding, these new devices will be presented along with a selected physics case.
International Nuclear Information System (INIS)
Kotthaus, Tanja
2010-01-01
In this thesis five heavy deformed isotopes from the mass region A≥230, namely 234 U, 233 U, 231 Th, 230 Pa and 232 Pa, were investigated by means of deuteron-induced neutron transfer reactions. The even-even isotope 234 U has been studied with the 4π-γ-spectrometer MINIBALL at the Cologne Tandem accelerator. Excited nuclei in the isotope 234 U were produced using the reaction 235 U(d,t) at a beam energy of 11 MeV. The target thickness was 3.5 mg/cm 2 . The analysis of the γγ-coincidence data yielded a reinterpretation of the level scheme in 12 cases. Considering its decay characteristics, the 4 + state at an excitation energy of 1886.7 keV is a potential candidate for a two-phonon vibrational state. The isotopes 233 U, 231 Th, 230 Pa and 232 Pa were investigated at the Munich Q3D spectrometer. For each isotope an angular distribution with angles between 5 and 45 were measured. In all four cases the energy of the polarized deuteron beam (vector polarization of 80%) was 22 MeV. As targets 234 U (160 μg/cm 2 ), 230 Th (140 μg/cm 2 ) and 231 Pa (140 μg/cm 2 ) were used. The experimental angular distributions were compared to results of DWBA calculations. For the odd isotope 233 U spin and parity for 33 states are assigned and in the other odd isotope 231 Th 22 assignments are made. The excitation spectra of the two odd-odd isotopes 230 Pa and 232 Pa were investigated for the first time. For the isotope 230 Pa 63 states below an excitation energy of 1.5 MeV are identified. Based on the new experimental data the Nilsson configuration of the ground state is either 1/2[530] p -5/2[633] n or 1/2[530] p +3/2[631] n . In addition 12 rotational bands are proposed and from this six values for the GM splitting energy are deduced as well as two new values for the Newby shift. In the other odd-odd isotope 232 Pa 40 states below an excitation energy of 850 keV are observed and suggestions for the groundstate band and its GM partner are made. From this one GM splitting
Energy Technology Data Exchange (ETDEWEB)
Bouneau, S.; Azaiez, F.; Duprat, J. [IPN, Orsay (France)] [and others
1996-12-31
The study of the superdeformed (SD) {sup 196}Pb nucleus has been revisited using the EUROGAM phase 2 spectrometer. In addition to the known yrast and two lowest excited SD bands, a third excited SD band has been seen. All of the three excited bands were found to decay to the yrast SD band through, presumably, E1 transitions, allowing relative spin and excitation energy assignments. Comparisons with calculations using the random-phase approximation suggest that all three excited bands can be interpreted as octupole vibrational structures.
Yrast spectroscopy in {sup 49-51}Ti via fusion-evaporation reaction induced by a radioactive beam
Energy Technology Data Exchange (ETDEWEB)
Niikura, M.; Ideguchi, E.; Michimasa, S.; Ota, S.; Shimoura, S.; Wakabayashi, Y. [University of Tokyo, Center for Nuclear Study, Wako, Saitama (Japan); Aoi, N.; Baba, H.; Fukuchi, T.; Ichikawa, Y.; Kubo, T.; Kurokawa, M.; Ohnishi, T.; Suzuki, H.; Yoshida, K. [RIKEN Nishina Center, Wako, Saitama (Japan); Iwasaki, H.; Onishi, T.K.; Suzuki, D. [University of Tokyo, Department of Physics, Tokyo (Japan); Liu, M.; Zheng, Y. [Chinese Academy of Sciences, Institute of Modern Physics, Lanzhou (China)
2009-12-15
In-beam {gamma} -ray spectroscopy of high-spin states in {sup 49-51}Ti was performed via the fusion-evaporation reaction using a radioactive beam. By excitation function and {gamma} - {gamma} coincidence analysis, yrast high-spin levels up to I=(21/2{sup -}),(11{sup +}),(17/2{sup -}) in {sup 49-51}Ti were determined. The levels were compared with full-pf -shell model calculation. The level structure indicates the persistency of the N=28 shell gap at yrast states in {sup 49-51}Ti. (orig.)
Exotic nuclei: another aspect of nuclear structure
International Nuclear Information System (INIS)
Dobaczewski, J.; Blumenfeld, Y.; Flocard, H.; Garcia Borge, M.J.; Nowacki, F.; Rombouts, S.; Theisen, Ch.; Marques, F.M.; Lacroix, D.; Dessagne, P.; Gaeggeler, H.
2002-01-01
This document gathers the lectures made at the Joliot Curie international summer school in 2002 whose theme that year was exotic nuclei. There were 11 contributions whose titles are: 1) interactions, symmetry breaking and effective fields from quarks to nuclei; 2) status and perspectives for the study of exotic nuclei: experimental aspects; 3) the pairing interaction and the N = Z nuclei; 4) borders of stability region and exotic decays; 5) shell structure of nuclei: from stability to decay; 6) variational approach of system with a few nucleons; 7) from heavy to super-heavy nuclei; 8) halos, molecules and multi-neutrons; 9) macroscopic approaches for fusion reactions; 10) beta decay: a tool for spectroscopy; 11) the gas phase chemistry of super-heavy elements
Lifetime measurements in transitional nuclei by fast electronic scintillation timing
Caprio, M. A.; Zamfir, N. V.; Casten, R. F.; Amro, H.; Barton, C. J.; Beausang, C. W.; Cooper, J. R.; Gürdal, G.; Hecht, A. A.; Hutter, C.; Krücken, R.; McCutchan, E. A.; Meyer, D. A.; Novak, J. R.; Pietralla, N.; Ressler, J. J.; Berant, Z.; Brenner, D. S.; Gill, R. L.; Regan, P. H.
2002-10-01
A new generation of experiments studying nuclei in spherical-deformed transition regions has been motivated by the introduction of innovative theoretical approaches to the treatment of these nuclei. The important structural signatures in the transition regions, beyond the basic yrast level properties, involve γ-ray transitions between low-spin, non-yrast levels, and so information on γ-ray branching ratios and absolute matrix elements (or level lifetimes) for these transitions is crucial. A fast electronic scintillation timing (FEST) system [H. Mach, R. L. Gill, and M. Moszyński, Nucl. Instrum. Methods A 280, 49 (1989)], making use of BaF2 and plastic scintillation detectors, has been implemented at the Yale Moving Tape Collector for the measurement of lifetimes of states populated in β^ decay. Experiments in the A100 (Pd, Ru) and A150 (Dy, Yb) regions have been carried out, and a few examples will be presented. Supported by the US DOE under grants and contracts DE-FG02-91ER-40609, DE-FG02-88ER-40417, and DE-AC02-98CH10886 and by the German DFG under grant Pi 393/1.
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.)
International Nuclear Information System (INIS)
Kalpakchieva, R.; Cherepanov, E.A.
1993-01-01
The international school-seminar on heavy ion physics had been organized in Dubna in may of 1993. The scientific program of reports covers the following main topics: synthesis and properties of heavy nuclei; synthesis and investigation of properties of exotic nuclei; experiments with radioactive nuclear beams; interaction between complex nuclei at low and intermediate energies. It also includes reports on laser spectroscopy and exotic nuclear beams, on some application of heavy ion beams for the problems of solid state physics, on construction of multidetector facilities and on developing of heavy ion accelerator complexes. Short communication
Energy Technology Data Exchange (ETDEWEB)
Ali, M A [Nuclear Physics Department, Nuclear Research Center, Atomic Energy Authority, Cairo (Egypt); Sukhovoj, A M; Khitrov, V A [Joint institute for nuclear research Frank laboratory of Neutron physics, Dubna, (Russian Federation)
1996-03-01
The compound state gamma-decays, after thermal neutron capture, in the {sup 156,158} Gd, {sup 164} Dy, and {sup 174} Yb deformed nuclei and the {sup 196} Pt transitional nucleus were measured and analysed in a search for giant magnetic dipole resonances (GMDR) levels built on the ground states of these nuclei. The two-step cascade intensities for these nuclei are given and the level densities are deduced. The results obtained are compared with theoretical predictions. For the deformed nuclei, the analysis shows that these GMDR levels built on the ground state are not or probably very weakly populated. The enhancements experimentally observed in the two-step gamma-decay of the compound state of the {sup 196} Pt nucleus to its ground state can be explained qualitatively by the presence of GMDR states at an energy of about 2.8 MeV, with a full width at half maximum of about 1 MeV. 3 tabs.
Energy Technology Data Exchange (ETDEWEB)
Gastebois, J. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires
1968-06-01
The experimental results obtained in the study of the (d,p) reactions, at E{sub d} = 12 MeV, on the three even-even deformed nuclei {sup 170}Yb, {sup 172}Yb and {sup 174}Yb have been analysed in terms of DWBA calculations. The spectroscopic information relative to the odd final nuclei have been compared with the predictions of the collective model and of the Nilsson's model. The effect of various parameters used in the DWBA analysis (form factors, optical wave functions) has been carefully studied. The observed differences between the three final nuclei are qualitatively reproduced in the experimental study of resonances, seen in excitation functions of elastically and inelastically scattered protons on the same target nuclei, and corresponding to analogue states in the three nuclei {sup 171}Lu, {sup 173}Lu and {sup 175}Lu. (author) [French] Les resultats experimentaux de l'etude des reactions (d.p) a E{sub d} = 12 MeV, sur les noyaux deformes pairs-pairs {sup 170}Yb, {sup 172}Yb et {sup 174}Yb ont ete interpretes dans le cadre de l'approximation de Born des ondes deformees. Les informations spectroscopiques relatives aux noyaux impairs finals ont ete comparees aux predictions du modele collectif et du modele de Nilsson, apres avoir examine avec soin l'influence des differents parametres (facteurs de forme, fonctions d'onde 'optiques') utilises lors de l'analyse. Les differences observees entre les trois noyaux finals sont qualitativement reproduites par les resultats experimentaux de l'etude de resonances dans les fonctions d'excitation de diffusion elastique et inelastique de protons sur les memes noyaux-cibles, lors de la recherche d'etats analogues dans les noyaux {sup 171}Lu, {sup 173}Lu et {sup 175}Lu. (auteur)
Change of deformation at the backbending in the yrast superdeformed band of {sup 144}Gd
Energy Technology Data Exchange (ETDEWEB)
Ur, C.A.; Bolzonella, G.P.; Bazzacco, D. [dell`Universita, Padova (Italy)]|[INFN, Padova (Italy)] [and others
1996-12-31
A mean lifetime measurement using the Doppler shift attenuation method has been performed at GASP in order to extract the quadrupole moment of the yrast SD band of {sup 144}Gd. The extracted intrinsic quadrupole moments, being Q{sub 0}=13.7 eb above the backbending and Q{sub 0}=11.8 eb below the backbending, are consistent with a change of deformation from {beta}{sub 2}=0.51 (at {beta}{sub 4} {approx} 0.050) to {beta}{sub 2}=0.45 (at {beta}{sub 4} {approx}0.035). The experimental results are in nice agreement with the theoretical predictions, which revealed that the second well in {sup 144}Gd arises essentially from the very favored shell structure at N=80 and Z=64. The occupation at higher frequency of the aligned N=6 proton orbitals drives the nucleus to a slightly more deformed shape.
Study of yrast bands and electromagnetic properties in neutron-rich 114-128Cd isotopes
Chaudhary, Ritu; Pandit, Rakesh K.; Devi, Rani; Khosa, S. K.
2018-02-01
The projected shell model framework has been employed to carry out a systematic study on the deformation systematics of E (21+) and E (41+) / E (21+) values, BCS subshell occupation numbers, yrast spectra, backbending phenomena and electromagnetic quantities in 114-128Cd isotopes. Present calculations reproduce the observed systematics of the E (21+), R42 and B (E 2 ;2+ →0+) values for 114-128Cd isotopic mass chain and give the evidence that deformation increases as one moves from 114Cd to 118Cd, thereafter it decreases up to 126Cd. This in turn confirms 118Cd to be the most deformed nucleus in this set of isotopic mass chain. The emergence of backbending, decrease in B (E 2) values and change in g-factors in all these isotopes are intimately related to the crossing of g-band by 2-qp bands.
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
International Nuclear Information System (INIS)
Ghodsi, O. N.; Zanganeh, V.
2009-01-01
In the current study, a simulation technique has been employed to calculate the total potential between two deformed nuclei. It has been shown that this simulation technique is an efficient one for calculating the total potential for all possible orientations between the symmetry axes of the interacting nuclei using the realistic nuclear matter density and the M3Y nucleon-nucleon effective forces. The analysis of the results obtained for the 48 Ca+ 238 U, 46 Ti+ 46 Ti, and 27 Al+ 70 Ge reactions reveal that considering the density dependent effects in the M3Y forces causes the nuclear potential to drop by an amount of 0.4 MeV.
Marinov, Amnon; Kolb, D.; Weil, J.L.
2001-01-01
Relatively low energy and very enhanced alpha-particle groups have been observed in various actinide fractions produced via secondary reactions in a CERN W target which had been irradiated with 24-GeV protons. In particular, 5.14, 5.27 and 5.53 MeV alpha-particle groups with corresponding half-lives of 3.8(+ -)1.0 y, 625(+ -)84 d and 26(+ -)7 d, have been seen in Bk, Es and Lr-No sources, respectively. The measured energies are a few MeV lower than the known g.s. to g.s. alpha-decays in the corresponding neutron-deficient actinide nuclei. The half-lives are 4 to 7 orders of magnitude shorter than expected from the systematics of alpha-particle decay in this region of nuclei. The deduced evaporation residue cross sections are in the mb region, about 4 orders of magnitude higher than expected. A consistent interpretation of the data is given in terms of production of long-lived isomeric states in the second and third wells of the potential-energy surfaces of the parent nuclei, which decay to the corresponding w...
Thermodynamics of pairing phase transition in nuclei
International Nuclear Information System (INIS)
Karim, Afaque; Ahmad, Shakeb
2014-01-01
The pairing gaps, pairing energy, heat capacity and entropy are calculated within BCS (Bardeen- Cooper-Schrieffer) based quasi particle approach, including thermal fluctuations on pairing field within pairing model for all nuclei (light, medium, heavy and super heavy nuclei). Quasi particles approach in BCS theory was introduced and reformulated to study various properties. For thermodynamic behavior of nuclei at finite temperatures, the anomalous averages of creation and annihilation operators are introduced. It is solved self consistently at finite temperatures to obtain BCS Hamiltonian. After doing unitary transformation, we obtained the Hamiltonian in the diagonal form. Thus, one gets temperature dependence gap parameter and pairing energy for nuclei. Moreover, the energy at finite temperatures is the sum of the condensation energy and the thermal energy of fermionic quasi particles. With the help of BCS Hamiltonian, specific heat, entropy and free energy are calculated for different nuclei. In this paper the gap parameter occupation number and pairing energy as a function of temperature which is important for all the light, medium, heavy and super heavy nuclei is calculated. Moreover, the various thermo dynamical quantities like specific heat, entropy and free energy is also obtained for different nuclei. Thus, the thermodynamics of pairing phase transition in nuclei is studied
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
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
International Nuclear Information System (INIS)
Gomez Aleixandre, J. L.
1967-01-01
145 stars with N h >8 produced by the interactions of 13.8 GeV/c protons with Ag and Br nuclei have been analysed. The emulsion stack was irradiated in a 170 K gauss magnetic field. Statistical results concerning the main characteristics of the different particles emitted are given and the energy balance is evaluated. The main features of both 24 GeV/c protons and 17 GeV/c π- interactions are compared with those we have found for 13.8 GeV/c protons interactions. (Author) 27 refs
Triaxial energy relation to describe rotational band in 98-112Ru nuclei
International Nuclear Information System (INIS)
Singh, Yuvraj; Gupta, K.K.; Bihari, Chhail; Varshney, A.K.; Varshney, Mani; Singh, M.; Gupta, D.K.
2010-01-01
In a broader perspective rotation vibration coupling parameter (b) is considered changing with the change in excitation energy (ε 1 ) and is evaluated on fitting experimental energy for 98-112 Ru isotopes in the frame work of general asymmetric rotor model. The moment of inertia parameter (a), common to yrast and quasi-γ band, is calculated from deformation parameter (β) using general empirical relation. The present work is undertaken to suggest some suitable equation for the trajectories which are similar in shape in 98-112 Ru nuclei
Low-energy E1 transitions and octupole softness in odd-A deformed nuclei
Energy Technology Data Exchange (ETDEWEB)
Hagemann, G B [Niels Bohr Inst., Copenhagen (Denmark); Hamamoto, I [Lund Univ. (Sweden). Dept. of Mathematical Physics; Kownacki, J; Satula, W [Warsaw Univ. (Poland)
1992-08-01
It is found that B(E1) values for yrast spectroscopy of deformed odd-A rare-earth nuclei calculated by using a model in which one quasiparticle is coupled to a rotor are more than an order of magnitude too small. Therefore, measured B(E1) values for {sup 169}Lu were analyzed by introducing parameters which effectively took octupole softness into account. Some preliminary results of the theoretical analysis which are presented in this paper still give do not agree completely with experiment. 4 refs., 1 tab., 5 figs.
International Nuclear Information System (INIS)
Fett, E.; Haatuft, A.; Olsen, J.M.
1977-01-01
A method is presented, which has been used to determine the pion multiplicity distributions for antiproton annihilations on free protons from a sample of events obtained in a heavy liquid bubble chamber experiment. The method uses data obtained in the experiment in question together with the usual invariance principles satisfied by strong interactions. Furthermore no particular nuclear model is assumed
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...
Energy Technology Data Exchange (ETDEWEB)
Massarczyk, Ralph Jens
2011-01-17
During the last hundred years several models were developed to describe the configuration of nuclei. These models have to make predictions, which should be comparable with experiments. As a standard type of experiment the nuclear resonance fluorescence was established. A nucleus is excited by irradiation with photons. By emitting one or more photons the nucleus decays back to the ground state. With this method it is possible to measure energy levels and to determine the strength of their excitation. A continuum of unresolved peaks gives additional strength. The existing setup at the linear electron accelerator ELBE of the Forschungszentrum Dresden-Rossendorf uses bremsstrahlung, produced as a secondary beam in a thin Niobium foil. During the years 2008/09 experiments on the nuclei of {sup 86}Kr and {sup 136}Ba took place there. In this work they will be analyzed. Photon flux and efficiency determination have been done as well as simulations on detector response and non-nuclear scattered background events. For this purpose the GEANT4 package was used. Finally the resulting cross sections were corrected for branching and feeding.
Energy Technology Data Exchange (ETDEWEB)
Zweidinger, Markus
2016-06-22
In the present work the dipole strength distribution in the stable even-even isotopes {sup 92}Zr and {sup 94}Zr is investigated. To excite the nuclei from the ground state to an excited state, real photons are used. This method is called Nuclear Resonance Fluorescence. The measurements were performed at two different setups. The first one is the Darmstadt High Intensity Photon Setup (DHIPS). At DHIPS the measurements yield information about the spin quantum number and the integrated cross section. The second part of the experiments took place at the High Intensity γ-ray Source (HIγS). Here, information about the parity quantum number and the averaged branching ratio of the excited state is accessible. In total, 105 dipole excited states in the nucleus {sup 92}Zr and 124 in the isotope {sup 94}Zr are observed, most of them for the first time. The extracted dipole strength distribution is investigated for the existence of the pygmy dipole resonance that was observed in neighboring nuclei. Furthermore, in previously performed experiments on the isotope {sup 90}Zr, the spin-flip M1 resonance was observed as well. Therefore, also the magnetic dipole strength is investigated. Further, by comparison with global systematics, the two-phonon state is identified. Additionally, the averaged branching ratio is compared to the results of theoretical calculations in the framework of the statistical model.
International Nuclear Information System (INIS)
Leoni, S.
2011-01-01
The population and γ decay of neutron rich nuclei around 48 Ca has been measured at Legnaro National Laboratory with the PRISMA-CLARA setup, using deep-inelastic collisions on 64 Ni, at 5.9 MeV/A. The reaction properties of the main products are investigated, focusing on total cross-sections and energy integrated angular distributions. Gamma spectroscopy studies are also performed for the most intense transfer channels, making use of angular distributions and polarization measurements to firmly establish spin and parity of the excited states. In the case of 49 Ca candidates for particle-core couplings are investigated and interpreted on basis of lifetime measurements and comparison with model predictions. (author)
Structure and symmetries of odd-odd triaxial nuclei
Energy Technology Data Exchange (ETDEWEB)
Palit, R. [Tata Institute of Fundamental Research, Department of Nuclear and Atomic Physics, Colaba, Mumbai (India); Bhat, G.H. [University of Kashmir, Department of Physics, Srinagar (India); Govt. Degree College Kulgam, Department of Physics, Kulgam (India); Sheikh, J.A. [University of Kashmir, Department of Physics, Srinagar (India); Cluster University of Srinagar, Srinagar, Jammu and Kashmir (India)
2017-05-15
Rotational spectra of odd-odd Rh and Ag isotopes are investigated with the primary motivation to search for the spontaneous chiral symmetry breaking phenomenon in these nuclei. The experimental results obtained on the degenerate dipole bands of some of these isotopes using a large array of gamma detectors are discussed and studied using the triaxial projected shell (TPSM) approach. It is shown that, first of all, to reproduce the odd-even staggering of the known yrast bands of these nuclei, large triaxial deformation is needed. This large triaxial deformation also gives rise to doublet band structures in many of these studied nuclei. The observed doublet bands in these isotopes are shown to be reproduced reasonably well by the TPSM calculations. Further, the TPSM calculations for neutron-rich nuclei indicate that the ideal manifestation of the chirality can be realised in {sup 106}Rh and {sup 112}Ag, where the doublet bands have similar electromagnetic properties along with small differences in excitation energies. (orig.)
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)
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
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
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
Energy Technology Data Exchange (ETDEWEB)
Kotov, A.A.; Gavrikov, Yu.A.; Vaishnene, L.A.; Vovchenko, V.G.; Poliakov, V.V.; Fedorov, O.Ya.; Chestnov, Yu.A.; Shchetkovskiy, A.I [Petersburg Nuclear Physics Institute, Gatchina, Leningrad district, Orlova roscha 1, 188300 (Russian Federation); Fukahori, T. [Japan Atomic Energy Research Institute, Tokai-mura, Ibaraki 319-1195 (Japan)
2005-07-01
The results of the total fission cross sections measurements for {sup nat}Pb, {sup 209}Bi, {sup 232}Th, {sup 233}U, {sup 235}U, {sup 238}U, {sup 237}Np and {sup 239}Pu nuclei at the energy proton range 200-1000 MeV are presented. Experiments were carried out at 1 GeV synchrocyclotron of Petersburg Nuclear Physics Institute (Gatchina). The measurement method is based on the registration in coincidence of both complementary fission fragments by two gas parallel plate avalanche counters, located at a short distance and opposite sides of investigated target. The insensitivity of parallel plate avalanche counters to neutron and light charged particles allowed us to place the counters together with target immediately in the proton beam providing a large solid angle acceptance for fission fragment registration and reliable identification of fission events. The proton flux on the target to be studied was determined by direct counting of protons by scintillation telescope. The measured energy dependence of the total fission cross sections is presented. Obtained results are compared with other experimental data as well as with calculation in the frame of the cascade evaporation model. (authors)
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
Identification of rotating and vibrating tetrahedrons in the heavy nucleus {sup 208}Pb
Energy Technology Data Exchange (ETDEWEB)
Heusler, A.
2017-11-15
Ten known states in the heavy nucleus {sup 208}Pb at 2.6 < E{sub x} < 7.9 MeV are described by rotating and vibrating tetrahedrons. The 3{sup -} and 4{sup +} yrast states are the first members of the rotational band. A 2{sup ±} doublet state with the 2{sup +} yrast state as one member and the newly recognized 2{sup -} yrast state as the other member, the 1{sup -} yrast state, and the third 0{sup +} state are the heads of the three elementary tetrahedral rotating and vibrating bands. The newly recognized state at E{sub x} = 4142 keV was assigned spin 2 in 1975 and is suggested to have negative parity by the absent {sup 208}Pb(α, α{sup '}) excitation. Four more states at 5.7 < E{sub x} < 7.9 MeV are identified as the next members of the three elementary tetrahedral rotating and vibrating bands. The ambiguous spin assignment to the state at E{sub x} = 7020 keV is settled with 3{sup -}, the state at E{sub x} = 7137 keV is assigned 4{sup -}. (orig.)
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
Quasi-SU(3) truncation scheme for even-even sd-shell nuclei
International Nuclear Information System (INIS)
Vargas, C.E.; Hirsch, J.G.; Draayer, J.P.
2001-01-01
The quasi-SU(3) symmetry was uncovered in full pf and sdg shell-model calculations for both even-even and odd-even nuclei. It manifests itself through a dominance of single-particle and quadrupole-quadrupole terms in a Hamiltonian used to describe well-deformed nuclei. A practical consequence of the quasi-SU(3) symmetry is an efficient basis truncation scheme. In [C.E. Vargas et al., Phys. Rev. C 58 (1998) 1488] it is shown that when this type of Hamiltonian is diagonalized in an SU(3) basis, only a few irreducible representations (irreps) of SU(3) are needed to describe the yrast band, the leading S=0 irrep augmented with the leading S=1 irreps in the proton and neutron subspaces. In the present article the quasi-SU(3) truncation scheme is used, in conjunction with a 'realistic but schematic' Hamiltonian that includes the most important multipole terms, to describe the energy spectra and B(E2) transition strengths of 20,22 Ne, 24 Mg and 28 Si. The effect of the size of the Hilbert space on both sets of observables is discussed, as well as the structure of the yrast band and the importance of the various terms in the Hamiltonian. The limitations of the model are explicitly discussed
Quasi-SU(3) truncation scheme for even-even sd-shell nuclei
Energy Technology Data Exchange (ETDEWEB)
Vargas, C.E. E-mail: cvargas@fis.cinvestav.mx; Hirsch, J.G. E-mail: hirsch@nuclecu.unam.mx; Draayer, J.P. E-mail: draayer@lsu.edu
2001-07-30
The quasi-SU(3) symmetry was uncovered in full pf and sdg shell-model calculations for both even-even and odd-even nuclei. It manifests itself through a dominance of single-particle and quadrupole-quadrupole terms in a Hamiltonian used to describe well-deformed nuclei. A practical consequence of the quasi-SU(3) symmetry is an efficient basis truncation scheme. In [C.E. Vargas et al., Phys. Rev. C 58 (1998) 1488] it is shown that when this type of Hamiltonian is diagonalized in an SU(3) basis, only a few irreducible representations (irreps) of SU(3) are needed to describe the yrast band, the leading S=0 irrep augmented with the leading S=1 irreps in the proton and neutron subspaces. In the present article the quasi-SU(3) truncation scheme is used, in conjunction with a 'realistic but schematic' Hamiltonian that includes the most important multipole terms, to describe the energy spectra and B(E2) transition strengths of {sup 20,22}Ne, {sup 24}Mg and {sup 28}Si. The effect of the size of the Hilbert space on both sets of observables is discussed, as well as the structure of the yrast band and the importance of the various terms in the Hamiltonian. The limitations of the model are explicitly discussed.
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.)
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.)
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
Proton radioactivity from proton-rich nuclei
International Nuclear Information System (INIS)
Guzman, F.; Goncalves, M.; Tavares, O.A.P.; Duarte, S.B.; Garcia, F.; Rodriguez, O.
1999-03-01
Half-lives for proton emission from proton-rich nuclei have been calculated by using the effective liquid drop model of heavy-particle decay of nuclei. It is shown that this model is able to offer results or spontaneous proton-emission half-life-values in excellent agreement with the existing experimental data. Predictions of half-life-values for other possible proton-emission cases are present for null orbital angular momentum. (author)
Nuclei far off the stability line
International Nuclear Information System (INIS)
Fenyes, T.
1978-01-01
Theoretical and experimental aspects of the formation of some ''exotic'' nuclei far off the stability line were reviewed in addition to the relevant results of research in this field. Results in beta- and gamma-ray spectroscopy, heavy-ion-spectroscopy, achievements in the fields of measuring the atomic mass, the moment, and the radius of the nuclei as well as some astronomical aspects were described. (Z.P.)
Stability of superheavy nuclei
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.
Structure and clusters of light unstable nuclei
International Nuclear Information System (INIS)
En'yo, Yoshiko
2010-01-01
As it is known, cluster structures are often observed in light nuclei. In the recent evolution of unstable nuclear research (on nuclei having unbalanced number of neutron and proton) further new types of clusters are coming to be revealed. In this report, structures of light unstable nuclei and some of the theoretical models to describe them are reviewed. The following topics are picked up. 1. Cluster structure and theoretical models, 2. Cluster structure of unstable nuclei (low excited state). 3. Cluster structure of neutron excess beryllium isotopes. 4. Cluster gas like state in C isotope. 5. Dineutron structure of He isotopes. Numbers of strange nuclear structures of light nuclei are illustrated. Antisymmetrized molecular dynamics (AMD) is the recently developed theoretical framework which has been successfully used in heavy ion reactions and nuclear structure studies. Successful application of AMD to the isotopes of Be, B and C are illustrated. (S. Funahashi)
Microscopic structure of high-spin vibrational states in superdeformed A=190 nuclei
Energy Technology Data Exchange (ETDEWEB)
Nakatsukasa, Takashi [Chalk River Labs., Ontario (Canada); Matsuyanagi, Kenichi [Kyoto Univ. (Japan); Mizutori, Shoujirou [Oak Ridge National Lab., TN (United States)] [and others
1996-12-31
Microscopic RPA calculations based on the cranked shell model are performed to investigate the quadrupole and octupole correlations for excited superdeformed (SD) bands in even-even A=190 nuclei. The K = 2 octupole vibrations are predicted to be the lowest excitation modes at zero rotational frequency. The Coriolis coupling at finite frequency produces different effects depending on the neutron and proton number of nucleus. The calculations also indicate that some collective excitations may produce moments of inertia almost identical to those of the yrast SD band. An interpretation of the observed excited bands invoking the octupole vibrations is proposed, which suggests those octupole vibrations may be prevalent in even-even SD A=190 nuclei.
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
International Nuclear Information System (INIS)
Azgui, F.; Emling, H.; Grosse, E.; Michel, C.; Simon, R.S.; Spreng, W.; Wollersheim, H.J.; Khoo, T.L.; Chowdhury, P.; Frekers, D.; Janssens, R.V.F.; Pakkanen, A.; Daly, P.J.; Kortelahti, M.; Schwalm, D.; Seiler-Clark, G.
1985-01-01
Measurements of feeding times of high spin yrast states up to spin 30 (h/2π) in 154 Dy and 36 (h/2π) in 152 Dy were utilized to obtain information about possible spin dependent shape changes. The reactions 25 Mg ( 134 Xe, 5n), 124 Sn ( 34 S, 4n) and 25 Mg ( 132 Xe, 5n), 122 Sn ( 34 S, 4n) were used to populate the high spin states in 154 Dy and 152 Dy, respectively. Feeding times as well as lifetimes were determined with the recoil distance technique. In 152 Dy only long feeding times (>=10 ps) could be identified, indicating that the aligned-particle yrast states are fed through configurations of similar character, with little direct population from collective cascades in the continuum region. In 154 Dy discrete states with I<=30 (h/2π) have lifetimes which are characteristically collective, whereas the preyrast cascades exhibit both fast (< or approx.1 ps) and slow (proportional10 ps) feeding components. The latter imply a change with increasing spin from collective to aligned-particle character, probably associated with a prolate to oblate shape transition. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Yavshits, S G [V.G. Khlopin Radium Institute, St. Petersburg (Russian Federation)
2011-05-15
scattering; - fission cross section (for heavy nuclei); - double differential cross sections of secondary protons and neutrons - multiplicities of secondary particles; - mass distribution of fission fragments. The development of model insight on reactions induced by nucleons in the intermediate energy region allows to obtain new information about fundamental processes in excited nuclei. The code developed give possibility both participants of the project and other experts to analyze new experimental data obtained after completion of the project. The libraries of nuclear data generated in the international ENDF-6 format can be directly used for design of new nuclear facilities, for calculations of radiation transport and activation in structural elements. The developed libraries will be accessible to all institutions and experts dealing with development of hybrid technologies.
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)
Structure of negative parity yrast bands in odd mass 125−131Ce ...
Indian Academy of Sciences (India)
gion close to the N = 82 shell gap and have been the subject of many experimen- tal studies as these nuclei exhibit a competition between spherical and deformed ... 127Ce nucleus [5,6] three bands were identified: two based on 5/2+ and ...
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.)
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
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
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.
Stability and production of superheavy nuclei
International Nuclear Information System (INIS)
Moeller, P.; Los Alamos National Lab., NM; Nix, J.R.
1997-01-01
Beyond uranium heavy elements rapidly become increasingly unstable with respect to spontaneous fission as the proton number Z increases, because of the disruptive effect of the long-range Coulomb force. However, in the region just beyond Z = 100 magic proton and neutron numbers and the associated shell structure enhances nuclear stability sufficient to allow observation of additional nuclei. Some thirty years ago it was speculated that an island of spherical, relatively stable superheavy nuclei would exist near the next doubly magic proton-neutron combination beyond 208 Pb, that is, at proton number Z 114 and neutron number N = 184. Theory and experiment now show that there also exists a rock of stability in the vicinity of Z = 110 and N = 162 between the actinide region, which previously was the end of the peninsula of known elements, and the predicted island of spherical superheavy nuclei slightly southwest of the magic numbers Z = 114 and N = 184. The authors review here the stability properties of the heavy region of nuclei. Just as the decay properties of nuclei in the heavy region depend strongly on shell structure, this structure also dramatically affects the fusion entrance channel. The six most recently discovered new elements were all formed in cold-fusion reactions. They discuss here the effect of the doubly magic structure of the target in cold-fusion reactions on the fusion barrier and on dissipation
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.)
Superdeformation in the A = 190 region. The lead nuclei
Energy Technology Data Exchange (ETDEWEB)
Henry, E A; Becker, J A; Brinkman, M J; Kuhnert, A; Stoyer, M A; Wang, T F; Yates, S W [Lawrence Livermore National Lab., CA (United States); Azaiez, F A; Beausang, C W; Burde, J; Deleplanque, M A; Diamond, R M; Draper, J E; Kelly, W H; Korton, W; Macchiavelli, A O; Oliveira, J; Rubel, E; Stephens, F S [Lawrence Berkeley Lab., CA (United States); Cizewski, J A [Rutgers--the State Univ., New Brunswick, NJ (United States)
1992-08-01
Superdeformed (SD) bands have been identified in the four even-even lead nuclei {sup 192}Pb, {sup 194}Pb, {sup 196}Pb, and {sup 198}Pb. The discovery of SD bands in these nuclei extended the region of superdeformation in the A = 190 region to Z = 82, and to neutron numbers up to N = 116. All of the SD bands in these nuclei are observed with transition energies ranging from about 250 keV to about 600 keV, with the lowest energy SD band transition for the entire region of 169 keV in {sup 194}Pb. The spins deduced for the lowest levels in the SD bands are 6, 8, and 12 for {sup 192,194,196,198}Pb, respectively. The dynamic moments of inertia of {sup 192}Pb and {sup 194}Pb are similar to each other, and to those of many other SD bands in this mass region. The dynamic moments of inertia of {sup 1}`9{sup 6}Pb and {sup 198}Pb are somewhat lower than those of {sup 192,194}Pb at a given frequency. The experimental lifetimes in {sup 194}Pb and the deduced transition quadrupole moments (Qt {approx} 20 eb) are equal to those of other nuclei in the region within errors. While SD bands have been observed in the odd-neutron Hg and Tl nuclei, SD bands have not been reported for the odd-neutron Pb nuclei. In this contribution we discuss briefly three topics on superdeformation in the lead nuclei. First, we have recent experimental data on {sup 196}Pb that extends our knowledge of the SD band in that nucleus. Next we review briefly the population of low-lying yrast levels from the decay of the SD bands in {sup 192,194,196}Pb. Finally, we summarize our efforts to identify superdeformation in the odd-A Pb nuclei. All of the experiments described here were performed using the HERA spectrometer at the 88-Inch Cyclotron facility located at Lawrence Berkeley Laboratory. (author) 9 refs., 4 figs.
Production of actinide nuclei by multi-nucleon transfer
Energy Technology Data Exchange (ETDEWEB)
Lauritsen, T.; Ahmad, I.; Carpenter, M.P. [and others
1995-08-01
Multi-nucleon transfers have increasingly allowed us to reach parts of the nuclear chart where regular compound nuclear reactions are prohibited. The interesting region of Ra and Rn, where a rich tapestry of nuclear structure manifests itself, is now accessible using this technique of deep inelastic scattering. In particular, these nuclei are predicted to lie at the onset of octupole deformation and the region is rich in examples of shape coexistence. There are several theoretical predictions of nuclear structure of these nuclei that have not been experimentally tested. Moreover, there is serious disagreement among these theories. We used a beam of {sup 136}Xe at 720 MeV from ATLAS on a target of {sup 232}Th to produce a range of Rn isotopes, with a mass from 220 to 224, and Ra isotopes with masses greater than 222. The beam energy, target and beam were selected carefully to enhance the cross-section for production of these nuclei and reduce the Doppler broadening of the gamma rays that were observed in the Argonne Notre Dame gamma-ray facility. The 12 germanium detectors of this array allowed the observation of gamma-gamma coincidences. The inner ball of 50 BGO detectors allowed us to record the multiplicity and sum-energy information for each event. The latter should permit us to determine the entry region in the products of the transfer reaction. We had four successful days of beam-time, when we collected in excess of 8 x 10{sup 7} events. Data analysis is in progress at the University of Liverpool. A complete set of spectroscopic information on the yrast structure of the many nuclei produced in this reaction is being extracted.
Quark distribution distortion in heavy nuclei
International Nuclear Information System (INIS)
Chela-Flores, J.
1984-10-01
Further consequences of sea-quark pairing are studied by looking at the underlying collective phenomena. We are led to variations of the quark distribution of single protons due to nuclear binding. A new prediction, subject to experimental verification, is discussed. (author)
Study of giant resonances in heavy nuclei
International Nuclear Information System (INIS)
Cataldi, M.I.C.
1986-01-01
The electrodisintegration cross section for 181 Ta, 208 Pb and 209 Bi was measured by counting the emitted neutrons, with incident electrons in the energy range 8-22 MeV. The data was analysed using the virtual photon method, in order to obtain a multipole decomposition and the intensities of Magnetic Dipole and Electric Quadrupole, isoscalar and isovector, in the Giant Resonance. The results obtained for the isovector Giant Quadrupole Resonance are compared with the measured photodisintegration cross section, using data from Saclay and Livermore. This comparision indicates that the photodisintegration data can be well explained assuming an isovector E2 Resonance located between 120 and 130 A -1/3 MeV, with an intensity of one isovector E2 sum. (author) [pt
Borromean structures in medium-heavy nuclei
DEFF Research Database (Denmark)
Hove, Dennis; Fedorov, Dmitri Vladimir; Fynbo, Hans Otto Uldall
2014-01-01
Borromean nuclear cluster structures are expected at the corresponding driplines. We locate the regions in the nuclear chart with the most promising constituents, it being protons and alpha-particles and investigate in details the properties of the possible borromean two-alpha systems in medium h...... 134Te−α−α structure in its ground state and low-lying spectrum....
International Nuclear Information System (INIS)
Oertzen, W. von; Voit, H.; Imanishi, B.
1988-10-01
This report contains a review article considering the evolution of direct mechanisms with incident energy in heavy ion reactions and two theoretical articles concerning two-center effects in transfer reactions between heavy ions and the nucleon promotion in heavy ion reactions. See hints under the relevant topics. (HSI)
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.)
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.
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.
Dipole cluster states in light, medium heavy and heavy nuclei
International Nuclear Information System (INIS)
Gai, Moshe
1984-01-01
Tests of the Vibron cluster model in sup(18)O, sup(218)Ra and sup(156)Yb are reported, as well as a test in progress in sup(52)Ti. Low lying negative parity states which appear to be members of rotational bands of alternating parity states with enhanced B(E1) intraband deexcitation rates are found. The cluster band, within the model framework, is also characterized by large alpha decay widths and enhanced radiative deexcitation widths of several multipolarities B(E1), B(E2), B(E3). A discussion of the model and the underlying, newly suggested dipole degree of freedom is presented. (author)
On the semiclassical description of rotating nuclei
International Nuclear Information System (INIS)
Durand, M.; Kunz, J.; Schuck, P.
1983-01-01
The technique of partial h-resummation is used to obtain semiclassical, i.e. average current distributions in the body fixed system of heavy nuclei. It thereby turns out that this average intrinsic current only flows in the nuclear surface. A Strutinsky smoothing of the current is also performed and gives nice agreement with the semiclassical results. We also show how one can incorporate superfluidity into the semiclassical treatment. To lowest order in h we find that the moment of inertia of superfluid nuclei is zero. The same result is obtained by a quantum mechanical calculation if the gap goes to infinity. The importance of including n-corrections is pointed out
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
Structure of neutron-rich nuclei
International Nuclear Information System (INIS)
Nazarewicz, W.
2000-01-01
Complete text of publication follows. The uncharted regions of the (N,Z) plane contain information that can answer many questions of fundamental importance for science: How many protons and neutrons can be clustered together by the strong interaction to form a bound nucleus? What are the proton and neutron magic numbers of the exotic nuclei? What are the properties of very short-lived exotic nuclei with extreme neutron-to-proton ratios? What is the effective nucleon-nucleon interaction in a nucleus that has a very large neutron excess? Nuclear life far from stability is different from that around the stability line; the promised access to completely new combinations of proton and neutron numbers offers prospects for new structural phenomena. The main objective of this talk is to discuss some of the challenges and opportunities of research with exotic nuclei. The covered topics will include: Theoretical challenges; Skins and halos in heavy nuclei; Shape coexistence in exotic nuclei; Beta-decays of neutron-rich nuclei. (author)
Study of fusion probabilities with halo nuclei using different proximity based potentials
International Nuclear Information System (INIS)
Kumari, Raj
2013-01-01
We study fusion of halo nuclei with heavy targets using proximity based potentials due to Aage Winther (AW) 95, Bass 80 and Proximity 2010. In order to consider the extended matter distribution of halo nuclei, the nuclei radii borrowed from cross section measurements are included in these potentials. Our study reveals that the barrier heights are effectively reduced and fusion cross sections are appreciably enhanced by including extended radii of these nuclei. We also find that the extended sizes of halos contribute towards enhancement of fusion probabilities in case of proton halo nuclei, but, contribute to transfer or break-up process rather than fusion yield in case of neutron halo nuclei
CERN. Geneva; Antinori, Federico
2001-01-01
Colliding two heavy nuclei at ultrarelativistic energies allows to create in the laboratory a bulk system with huge density, pressure and temperature and to study its properties. It is estimated that in Pb-Pb collisions at CERN-SPS we reach over an appreciable volume an energy density which exceeds by more than a factor 20 that of normal nuclear matter. At such densities, the hadrons are so closely packed that they interpenetrate; novel physics phenomena are expected to appear. QCD predicts that under such conditions a phase transition from a system composed of colourless hadrons to a Quark-Gluon Plasma (QGP) should occur. A rich ultrarelativistic heavy-ion physics programme is under way both at BNL-AGS and at CERN-SPS since 1986. The results obtained so far have led CERN to officially announce evidence for a new state of matter last year. A long-range programme of heavy-ion physics at higher energies is under way (BNL-RHIC) and in preparation (CERN-LHC). These lectures are meant as an introduction to the phy...
CERN. Geneva. Audiovisual Unit
2002-01-01
Colliding two heavy nuclei at ultrarelativistic energies allows to create in the laboratory a bulk system with huge density, pressure and temperature and to study its properties. It is estimated that in Pb-Pb collisions at CERN-SPS we reach over an appreciable volume an energy density which exceeds by more than a factor 20 that of normal nuclear matter. At such densities, the hadrons are so closely packed that they interpenetrate; novel physics phenomena are expected to appear. QCD predicts that under such conditions a phase transition from a system composed of colourless hadrons to a Quark-Gluon Plasma (QGP) should occur. A rich ultrarelativistic heavy-ion physics programme is under way both at BNL-AGS and at CERN-SPS since 1986. The results obtained so far have led CERN to officially announce evidence for a new state of matter last year. A long-range programme of heavy-ion physics at higher energies is under way (BNL-RHIC) and in preparation (CERN-LHC). These lectures are meant as an introduction to the phy...
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
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.)
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
Search for supermassive nuclei in nature
International Nuclear Information System (INIS)
Polikanov, S.; Sastri, C.S.; Herrmann, G.; Luetzenkirchen, K.; Overbeck, M.; Trautmann, N.
1990-11-01
We report on a search for supermassive nuclei in nature with masses up to 10 7 amu. Such exotic nuclei might consist, for example, of stable strange matter, which comprises a mixture of up, down, and strange quarks, or of relic particles from the early Universe. The experiments are based on Rutherford backscattering of heavy ions, preferably 238 U, from various target samples. The measured parameters of a deteced particle are its time-of-flight, scattering angle, and specific ionization. From this information the mass of the target nucleus can be inferred. Upper limits for the abundance of strange supermassive nuclei with masses A ≅ 4x10 2 to 10 7 amu relative to the number of nucleons were found to be in the range 10 -11 to 10 -15 . For the narrower mass range A ≅ 10 3 to 10 4 amu the limit is 2x10 -17 . (orig.)
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)
Spectroscopic Studies of Exotic Nuclei at ISOLDE
2002-01-01
Experiment IS50 is designed to: a) Investigate the full range of the @b strength function of heavy (A~$>$~48)~K nuclei b)~Study the decay of isomeric states in n-deficient bromine nuclei (A~=~72 and 70). The heavy K isotopes appeared to have complex decay schemes, including feeding by the @b-decay of levels having open neutron channels (Beta decay energy Q(@b) exceeds neutron binding energy S^n); in addition, a large fraction of the delayed transitions populate excited levels in the daughter nuclei. The allowed @b-decay selects states in the daughter nucleus with wave functions having a large overlap with the initial state. Hence, the @b strength functions, deduced from these deca reveal simple structures correlated to the particle-hole excitation energies in the Ca nuclei. These results are valuable for the application of the shell-model calculations far from stability. The delayed neutron spectra are measured with a large area curved scintillator in coincidence either with high resolution Ge(Li) detectors, ...
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)
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
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
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)
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
Scaling of nuclear modification factors for hadrons and light nuclei
Energy Technology Data Exchange (ETDEWEB)
Zhou, C.S. [Chinese Academy of Sciences, Shanghai Institute of Applied Physics, Shanghai (China); University of Chinese Academy of Sciences, Beijing (China); Ma, Y.G. [Chinese Academy of Sciences, Shanghai Institute of Applied Physics, Shanghai (China); ShanghaiTech University, Shanghai (China); Zhang, S. [Chinese Academy of Sciences, Shanghai Institute of Applied Physics, Shanghai (China)
2016-12-15
The number of constituent quarks (NCQ) scaling for hadrons and the number of constituent nucleons (NCN) scaling for light nuclei are proposed for nuclear modification factors (R{sub cp}) of hadrons and light nuclei, respectively, according to the experimental investigations in relativistic heavy-ion collisions. Based on the coalescence mechanism the scalings are performed for pions and protons at the quark level, and for light nuclei d(anti d) and {sup 3}He at the nucleonic level, respectively, formed in Au+Au and Pb+Pb collisions, and a nice scaling behaviour emerges. The NCQ or NCN scaling law of R{sub cp} can be, respectively, taken as a probe for the quark or nucleon coalescence mechanism for the formation of hadron or light nuclei in relativistic heavy-ion collisions. (orig.)
Studies of pear-shaped nuclei using accelerated radioactive beams
Gaffney, L P; Scheck, M; Hayes, A B; Wenander, F; Albers, M; Bastin, B; Bauer, C; Blazhev, A; Bonig, S; Bree, N; Cederkall, J; Chupp, T; Cline, D; Cocolios, T E; Davinson, T; DeWitte, H; Diriken, J; Grahn, T; Herzan, A; Huyse, M; Jenkins, D G; Joss, D T; Kesteloot, N; Konki, J; Kowalczyk, M; Kroll, Th; Kwan, E; Lutter, R; Moschner, K; Napiorkowski, P; Pakarinen, J; Pfeiffer, M; Radeck, D; Reiter, P; Reynders, K; Rigby, S V; Robledo, L M; Rudigier, M; Sambi, S; Seidlitz, M; Siebeck, B; Stora, T; Thoele, P; Van Duppen, P; Vermeulen, M J; von Schmid, M; Voulot, D; Warr, N; Wimmer, K; Wrzosek-Lipska, K; Wu, C Y; Zielinska, M
2013-01-01
There is strong circumstantial evidence that certain heavy, unstable atomic nuclei are ‘octupole deformed’, that is, distorted into a pear shape. This contrasts with the more prevalent rugby-ball shape of nuclei with reflection-symmetric, quadrupole deformations. The elusive octupole deformed nuclei are of importance for nuclear structure theory, and also in searches for physics beyond the standard model; any measurable electric-dipole moment (a signature of the latter) is expected to be amplified in such nuclei. Here we determine electric octupole transition strengths (a direct measure of octupole correlations) for short-lived isotopes of radon and radium. Coulomb excitation experiments were performed using accelerated beams of heavy, radioactive ions. Our data on and $^{224}$Ra show clear evidence for stronger octupole deformation in the latter. The results enable discrimination between differing theoretical approaches to octupole correlations, and help to constrain suitable candidates for experimental...
The dynamics of the nuclei-nuclei interactions at very high energies
International Nuclear Information System (INIS)
Blaizot, J.P.
1988-01-01
The lectures on the dynamics of nuclei-nuclei interactions at very high energies, presented in the Summer School on Nuclear Physics and Particle Physics (1988), are shown. The equation of state of the hadronic matter is analyzed, by means of simple models, and some orders of magnitude can be asserted. The main characteristics of the high energy hadronic interactions are recalled. The basis of the dynamics of the relativistic fluids are given. Applications of this dynamics in the description of the space-time evolution of a plasma, generated by heavy ions collision, are carried out [fr
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
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
The intergalactic propagation of ultrahigh energy cosmic ray nuclei
Energy Technology Data Exchange (ETDEWEB)
Hooper, Dan; /Fermilab; Sarkar, Subir; /Oxford U., Theor. Phys.; Taylor, Andrew M.; /Oxford U.
2006-08-01
We investigate the propagation of ultra-high energy cosmic ray nuclei (A = 1-56) from cosmologically distant sources through the cosmic radiation backgrounds. Various models for the injected composition and spectrum and of the cosmic infrared background are studied using updated photodisintegration cross-sections. The observational data on the spectrum and the composition of ultra-high energy cosmic rays are jointly consistent with a model where all of the injected primary cosmic rays are iron nuclei (or a mixture of heavy and light nuclei).
Localization effects in heavy ion collisions
International Nuclear Information System (INIS)
Donangelo, R.J.
1984-01-01
Radial and angular localization in heavy ion reactions on deformed nuclei is discussed. A theoretical method appropriate to study these localization effects is briefly described and then applied to the determination of deformed heavy ion potentials from inclastic scattering data. It is argued that one-and two-nucleon transfer reactions on deformed nuclei can provide a probe of nuclear structure in high angular momentum states and be at least qualitatively analyzed in the light of these localization concepts. (Author) [pt
Liu Zhong; Guo Ying Xiang; Zhou Xiao Hong; Lei Xiang Guo; LiuMinLiang; Luo Wan Ju; He Jian Jun; Zheng Yong; Pan Qiang Yan; Gan Zai Guo; Luo Yi Xiao; Hayakawa, T; Oshima, M; Toh, Y; Shizima, T; Hatsukawa, Y; Osa, A; Ishii, T; Sugawara, M
2002-01-01
Excited states of sup 1 sup 4 sup 2 Ce, populated in deep inelastic reactions of sup 8 sup 2 Se projectiles bombarding sup 1 sup 3 sup 9 La target, have been studied to medium spins using in-beam gamma spectroscopy techniques. Three new levels have been identified at 2625, 2995 and 3834 keV, and assigned as 8 sup + , 9 sup ( sup - sup ) and 11 sup ( sup - sup ) , respectively, based on the analysis of the properties of gamma transitions. These new yrast states follow well the level systematics of N 84 isotones. Their structures have been discussed with the help of empirical shell-model calculations
Decay properties of heavier nuclei and mass formula
International Nuclear Information System (INIS)
Uno, Masahiro
2000-01-01
The stabilities of heavy nuclei, including super-heavy elements, are governed by alpha decay and fission. Some exotic types of decay, such as heavy cluster decay, which does not occur so frequently as to govern stability, have been also reported. The half-time estimations of various types of decay are reviewed. And the possibility of decay, mainly in case of heavy cluster decay, is discussed with Q-value obtained from mass formulae as well. Some topics concerning other types of exotic decay are presented. Recent trends in the research on mass formula are reviewed from the historical point of view, to get perspectives of future development. (Yamamoto, A.)
Decay properties of heavier nuclei and mass formula
Energy Technology Data Exchange (ETDEWEB)
Uno, Masahiro [Ministry of Education, Science and Culture, Tokyo (Japan)
2000-03-01
The stabilities of heavy nuclei, including super-heavy elements, are governed by alpha decay and fission. Some exotic types of decay, such as heavy cluster decay, which does not occur so frequently as to govern stability, have been also reported. The half-time estimations of various types of decay are reviewed. And the possibility of decay, mainly in case of heavy cluster decay, is discussed with Q-value obtained from mass formulae as well. Some topics concerning other types of exotic decay are presented. Recent trends in the research on mass formula are reviewed from the historical point of view, to get perspectives of future development. (Yamamoto, A.)
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.)
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)
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.
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
Pions in nuclei, from virtual-pion exchange to real-pion transfer
International Nuclear Information System (INIS)
Yamazaki, Toshimitsu.
1988-07-01
Tracing the work of Miyazawa on nuclear magnetic moments, we discuss possible experimental ways to see whether a real pion exists in nuclei or not. While virtual pions are known to play an important role in nuclei, as clarified experimentally from anomalous orbital g factors of nucleons in nuclei, nearly nothing is known for the behavior of real pions in nuclei. We have shown that deeply bound hybrid states of π - are expected to exist in heavy nuclei, which can be populated by ''pion transfer'' reactions. (author)
Compound nuclei at high angular momentum. High-spin γ-ray spectroscopy: past successes, future hopes
International Nuclear Information System (INIS)
Diamond, R.M.
1984-01-01
The addition of angular momentum to a nucleus presents a whole new dimension, a new coordinate axis, along which to study changes in nuclear behavior and structure. Nuclei can carry angular momentum in two principal ways: by the collective rotation of a deformed nucleus as a whole and by the alignment along the rotation axis of individual high-j nucleons. For spherical (or near-spherical) nuclei, the latter mode is the only one possible. The levels of 212 Rn illustrate a scheme of particle alignment; it is quite irregular with transitions of a variety of electromagnetic types and with little pattern to the level spacing. On the left, the yrast band of 238 U is shown, a predominantly rotational scheme with only strongly enhanced electric quadrupole transitions and a level spacing that approximates that of a rigid rotor, E = I(I + 1)h 2 /2 J and E/sub γ/ = (4I - 2)h 2 /2 J, where J is the moment of inertia. Most nuclei, however, combine both types of motion, and it is this interplay between collective and single-particle motion that makes the behavior of nuclei along the angular momentum coordinate so fascinating and so rich in variety. Data are shown for Yb isotopes, and Er isotopes are discussed
Dynamical moments of inertia for superdeformed nuclei
International Nuclear Information System (INIS)
Obikhod, T.V.
1995-01-01
The method of quantum groups has been applied for calculation the dynamical moments of inertia for the yrast superdeformed bands in 194 Hg and 192 Hg as well as to calculation of the dynamical moments of inertia of superdeformed bands in 150 Gd and 148 Gd
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
Level structure of 68149Er81 and high-spin isomerism in proton-rich N=81, 82, 83 nuclei
International Nuclear Information System (INIS)
Broda, R.; Daly, P.J.; McNeill, J.; Janssens, R.V.F.; Radford, D.C.
1987-01-01
The level structure of the N=81 nucleus 149 Er has been studied by γ-ray spectroscopy following the reaction 92 Mo+255 MeV 60 Ni. Yrast levels in 149 Er are established up to ≅ 3.3 MeV, including 0.61 and 4.8 μs isometric states. Most of the observed levels are interpreted as seniority-three states arising from the coupling of s 1/2 , d 3/2 and h 11/2 neutron holes with πh n 11/2 . Isomers identified in the reaction 96 Ru+255 MeV 58 Ni are tentatively assigned to 151 Yb. The B(E2) values of high-spin isomers in Z=66-70, N=81-83 nuclei are surveyed. (orig.)
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.))
Gamma rays and neutrinos from the Crab Nebula produced by pulsar accelerated nuclei
Bednarek, W.; Protheroe, R. J.
1997-01-01
We investigate the consequences of the acceleration of heavy nuclei (e.g. iron nuclei) by the Crab pulsar. Accelerated nuclei can photodisintegrate in collisions with soft photons produced in the pulsar's outer gap, injecting energetic neutrons which decay either inside or outside the Crab Nebula. The protons from neutron decay inside the nebula are trapped by the Crab Nebula magnetic field, and accumulate inside the nebula producing gamma-rays and neutrinos in collisions with the matter in t...
Mechanism of disintegration of sup 2 sup 3 sup 8 U nuclei by relativistic projectiles
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
3rd International conference on nuclei far from stability, Cargese, Corsica, 19-26 May 1976
International Nuclear Information System (INIS)
1976-01-01
These conference proceedings contain 103 contributions which are grouped under the following headings: Experimental methods and techniques; Perspectives in research on exotic nuclei; Nuclear masses - experiment and theory; Nuclear spins, moments, and radii; Light nuclei; Delayed particle emission and statistical aspects; Excited states of neutron-deficient nuclei; Excited states of fission products and other neutron-rich isotopes; Heavy elements and astrophysical aspects. Also included are the Scientific programme and a List of participants. (AJ)
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
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
Alpha decay and cluster decay of some neutron-rich actinide nuclei
Indian Academy of Sciences (India)
2017-02-09
Feb 9, 2017 ... Abstract. Nuclei in the actinide region are good in exhibiting cluster radioactivity. In the present work, the half-lives of α-decay and heavy cluster emission from certain actinide nuclei have been calculated using cubic plus Yukawa plus exponential model (CYEM). Our model has a cubic potential for the ...
Intruder bands in Z = 51 nuclei
International Nuclear Information System (INIS)
LaFosse, D.R.
1993-01-01
Recent investigations of h 11/2 proton intruder bands in odd 51 Sb nuclei are reported. In addition to experiments performed at SUNY Stony Brook and Chalk River, data from Early Implementation of GAMMASPHERE (analysis in progress) are presented. In particular, the nuclei 109 Sb and 111 Sb are discussed. Rotational bands based on the πh 11/2 orbital coupled to a 2p2h deformed state of the 50 Sn core have been observed. These bands have been observed to high spin, and in the case of 109 Sb to a rotational frequency of 1.4 MeV, the highest frequency observed in a heavy nucleus. The dynamic moments of inertia in these bands decrease slowly with frequency, suggesting a gradual band termination. The systematics of such bands in 109-119 Sb will be discussed
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
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.)
Disintegration of comet nuclei
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.
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
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
Energy Technology Data Exchange (ETDEWEB)
Barloutaud, R [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires
1958-06-15
The following nuclei were excited by protons of 5 MeV maximum energy: {sup 182}W - {sup 184}W - {sup 186}W - {sup 186}Os - {sup 188}Os - {sup 189}Os - {sup 190}Os - {sup 192}Os - {sup 194}Pt - {sup 196}Pt - {sup 198}Pt - {sup 198}Hg - {sup 200}Hg - {sup 202}Hg - {sup 204}Hg - {sup 206}Pb. The reduced probabilities of the various transitions were deduced from the coulomb excitation cross-section measurements. For some even-even nuclei two 2 + levels were excited. The properties of the excited levels are interpreted in terms of the collective model. (author) [French] Au moyen de protons d'energie inferieure a 5 MeV, l'excitation coulombienne des noyaux suivants a ete etudiee: {sup 182}W - {sup 184}W - {sup 186}W - {sup 186}Os - {sup 188}Os - {sup 189}Os - {sup 190}Os - {sup 192}Os - {sup 194}Pt - {sup 196}Pt - {sup 198}Pt - {sup 198}Hg - {sup 200}Hg - {sup 202}Hg - {sup 204}Hg - {sup 206}Pb. La mesure de la section efficace d'excitation coulombienne a permis de deduire les -probabilites reduites des diverses transitions observees. Dans certains noyaux pair-pair, deux niveaux de caractere 2 + ont ete excites. L'interpretation de ces niveaux en termes de niveaux de rotation et de niveaux de vibration a l'aide du modele collectif est discutee. En particulier, la variation des proprietes de ces niveaux avec la deformation nucleaire permet de fixer des limites a la validite des diverses hypotheses entrant dans le modele collectif. (auteur)
Energy Technology Data Exchange (ETDEWEB)
Dobaczewski, J [Warsaw Univ., Institute of Theoretical Physics (Poland); Blumenfeld, Y; Flocard, H; Garcia Borge, M J; Nowacki, F; Rombouts, S; Theisen, Ch; Marques, F M; Lacroix, D; Dessagne, P; Gaeggeler, H
2002-07-01
This document gathers the lectures made at the Joliot Curie international summer school in 2002 whose theme that year was exotic nuclei. There were 11 contributions whose titles are: 1) interactions, symmetry breaking and effective fields from quarks to nuclei; 2) status and perspectives for the study of exotic nuclei: experimental aspects; 3) the pairing interaction and the N = Z nuclei; 4) borders of stability region and exotic decays; 5) shell structure of nuclei: from stability to decay; 6) variational approach of system with a few nucleons; 7) from heavy to super-heavy nuclei; 8) halos, molecules and multi-neutrons; 9) macroscopic approaches for fusion reactions; 10) beta decay: a tool for spectroscopy; 11) the gas phase chemistry of super-heavy elements.
International Nuclear Information System (INIS)
Simonov, Yu.A.
1989-01-01
To apply QCD to nuclear physics one needs methods of long-distance QCD. A new method, method of Confining Background Fields, CBF, which incorporates confinement, is presented with applications to heavy and light quarks, both in mesons and baryons. Spin-dependent forces are calculated for light and heavy quarks. The quark potential model in some limiting case is derived. 25 refs
Population of Nuclei Via 7Li-Induced Binary Reactions
International Nuclear Information System (INIS)
Clark, Rodney M.; Phair, Larry W.; Descovich, M.; Cromaz, Mario; Deleplanque, M.A.; Fall on, Paul; Lee, I-Yang; Macchiavelli, A.O.; McMahan, Margaret A.; Moretto, Luciano G.; Rodriguez-Vieitez, E.; Sinha, Shrabani; Stephens, Frank S.; Ward, David; Wiedeking, Mathis
2005-01-01
The authors have investigated the population of nuclei formed in binary reactions involving 7 Li beams on targets of 160 Gd and 184 W. The 7 Li + 184 W data were taken in the first experiment using the LIBERACE Ge-array in combination with the STARS Si ΔE-E telescope system at the 88-Inch Cyclotron of the Lawrence Berkeley National Laboratory. By using the Wilczynski binary transfer model, in combination with a standard evaporation model, they are able to reproduce the experimental results. This is a useful method for predicting the population of neutron-rich heavy nuclei formed in binary reactions involving beams of weakly bound nuclei formed in binary reactions involving beams of weakly bound nuclei and will be of use in future spectroscopic studies
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
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
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
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
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
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
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.)
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)
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
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)
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)
Electromagnetic properties of nuclei at high spins
International Nuclear Information System (INIS)
Leander, G.A.
1986-01-01
A photon emitted by an excited state is likely to carry away, at most, 1 or 2 h-bar of angular momentum. Therefore, a profusion of photons is needed to deexcite the rapidly rotating states of nuclei formed by heavy-ion reactions. The study of electromagnetic properties has become the primary source of information on nuclear structure at high spins and, also, at the warm temperatures present in the initial stage of the electromagnetic cascade process. The purpose of this paper is a review of the E1, M1, and E2 properties of such highly excited states. 42 refs., 5 figs
Conversion electron spectroscopy in transfermium nuclei
International Nuclear Information System (INIS)
Herzberg, R.D.
2003-01-01
Conversion electron spectroscopy is an essential tool for the spectroscopy of heavy deformed nuclei. The conversion electron spectrometer SACRED has been used in conjunction with the gas-filled recoil separator RITU to study conversion electron cascades in 254 No. The spectra reveal the ground state rotational bands down to low spin. A detailed analysis of the background seen for 254 No shows that approximately 40% of the decay path goes via excited high K bands which may be built on an isomer. (orig.)
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.)
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
Symmetries of Quadrupole-Collective Vibrational Motion in Transitional Even-Even 124−134Xenon Nuclei
Pietralla, N; Rainovski, G; Ahn, T; Bauer, C; Leske, J; Möller, O; Möller, T
2010-01-01
Projectile-Coulomb excitation of Xe isotopes has been performed at ANL using the Gammasphere array for the detection of γ-rays. The one-quadrupole phonon 2+ 1,ms mixed-symmetry state (MSS) has been traced in the stable N=80 isotones down to 134Xe. First, the data on absolute E2 andM1 transition rates quantify the amount of F-spin symmetry in these nuclei and provide a new local measure for the pn-QQ interaction. Second, the evolution of the 2+ 1,ms state has been studied along the sequence of stable even-even 124−134Xe isotopes that are considered to form a shape transition path from vibrational nuclei with vibrational U(5) symmetry near N=82 to γ-softly deformed shapes with almost O(6) symmetry. Third, our data on more than 50 absolute E2 transition rates between off-yrast low-spin states of 124,126Xe enable us to quantitatively test O(6) symmetry in these nuclei. As a result we find that O(6) symmetry is more strongly broken in the A=130 mass region than previously thought. The data will be discussed.
International Nuclear Information System (INIS)
Richter, A.
1977-01-01
Recent experimental work from the Darmstadt electron linear accelerator (DALINAC) is briefly summarized. Particular emphasis is given to the following topics: high resolution inelastic electron scattering (ΔE approximately 30 keV FWHM) has been used to study the radiative width and magnetization density of the 2 + , T = 1 state at 16.11 MeV in 12 C, E2 strength distribution in 28 Si below an excitation energy of 13 MeV and the isospin forbidden E1 electroexcitation of the 1 - , T = 0 state at 6.95 MeV in 40 Ca. High resolution inelastic electron scattering was also employed to determine certain M1 transitions in 14 N, 28 Si, 39 K, 58 Ni, 90 Zr and 208 Pb and the M2 strength distribution in the two heaviest nuclei. At medium energy resolution (ΔE approximately 200 keV FWHM) spectra at various angles and bombarding energies have been measured from (4-31) MeV for 208 Pb. They are being analyzed in order to determine E0, E1, E2, E3 and M1 giant resonance strength in the continuum. The Z and E dependence and the scaling behaviour of the atomic inner shell ionization cross section at relativistic electron impact is studied on gaseous and solid targets. (orig./BJ) [de
Energetic Nuclei, Superdensity and Biomedicine
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.…
Shape nuclei and nuclear reactions
International Nuclear Information System (INIS)
Yushkov, A.V.
1975-01-01
Experimental methods for obtaining the nucleus shape parameters are reviewed throughout the period of 1955-1975. Spatial properties of a nucleus, which can be directly or indirectly measured, are determined. They include: parameters of nucleus localization in space; parameters characterizing the nucleus nonsphericity; parameters of the nucleus nonaxiality. Dimensional parameters of a nucleus, namely, radius R and surface ΔR are derived from electron scattering. The deformation sign is indirectly obtained in the experiments. Parameters of the nucleus shape, namely, the sign and magnitude of nuclear deformation are derived from the mean energy proton scattering by a coupled channels method. The only direct way of deriving the nucleus surface deformation signs is the method of the Blaire phase shift. Results on scattering of electrons, protons, and α-particles on light and medium nuclei are reported. Data on the nucleus shape can be also obtained from reactions with heavy ions. A difference between strong absorptions of incident particles of high and average energy by a nucleus is noted. Numerous diagrams illustrate experimental and theoretical results
International Nuclear Information System (INIS)
Beck, Christian
2012-01-01
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 second volume follows the successful Lect. Notes Phys. 818 (Vol.1), and comprises six extensive lectures covering the following topics: - Microscopic cluster models - Neutron halo and break-up reactions - Break-up reaction models for two- and three-cluster projectiles - Clustering effects within the di-nuclear model - Nuclear alpha-particle condensates - Clusters in nuclei: experimental perspectives By promoting new ideas and developments while retaining a pedagogical style of presentation throughout, these lectures will serve as both a reference and an advanced teaching manual for future courses and schools in the fields of nuclear physics and nuclear astrophysics. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Beck, Christian (ed.) [Strasbourg Univ. (France). Inst. Pluridiciplinaire Hubert Curien
2012-07-01
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 second volume follows the successful Lect. Notes Phys. 818 (Vol.1), and comprises six extensive lectures covering the following topics: - Microscopic cluster models - Neutron halo and break-up reactions - Break-up reaction models for two- and three-cluster projectiles - Clustering effects within the di-nuclear model - Nuclear alpha-particle condensates - Clusters in nuclei: experimental perspectives By promoting new ideas and developments while retaining a pedagogical style of presentation throughout, these lectures will serve as both a reference and an advanced teaching manual for future courses and schools in the fields of nuclear physics and nuclear astrophysics. (orig.)
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)
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
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
Interactions of 400 GeV proton with Different target nuclei in emulsion
International Nuclear Information System (INIS)
El-Nadi, M.; Abdel-Halim, S.M.; Yasin, M.N.; El-Nagdy, M.S.
1995-01-01
The interaction characteristics of 400 GeV proton with emulsion nuclei were studied and discussed. The multiplicity distributions of secondary charged particles have been measured for 480 inelastic events and are compared with the results obtained in p-emulsion collisions at different energies. The integral distribution of the number of disintegrated particles from the target nuclei N h are used to separate the number of the inelastic interactions of proton with light (Cno) and heavy (Ag Br) nuclei in the emulsion. The interaction characteristics of proton (400 GeV) with different groups of target nuclei have been investigated
Interactions of 400 GeV protons with different target nuclei in emulsion
International Nuclear Information System (INIS)
El-Nadi, M.; Abdel Halim, S.M.; Yasin, M.N.; El-Nagdy, M.S.
1996-01-01
The interaction characteristics of 400 GeV protons with emulsion nuclei were studied and discussed. The multiplicity distributions of secondary charged particles have been measured for 480 inelastic events and are compared with the results obtained in p-emulsion (P-Em) collisions at different energies. The integral distribution of the number of disintegrated particles from the target nuclei N h is used to separate the number of the inelastic interactions of proton with light (CNO) and heavy (AgBR) nuclei in the emulsion. The interaction characteristics of protons (400 GeV) with different groups of target nuclei have been investigated. (author)
International Nuclear Information System (INIS)
Smith, C.H.L.
1977-01-01
The possibility that a new lepton may exist is discussed under the headings; theoretical reasons for the introduction of heavy leptons, classification of heavy leptons (ortho and paraleptons), discrimination between different types of lepton, decays of charged heavy leptons, production of charged heavy leptons (in e + e - storage rings, neutrino production, photoproduction, and hadroproduction), neutral heavy leptons, and hadroleptons. (U.K.)
Preface to the Special Issue: Chiral Symmetry in Hadrons and Nuclei
International Nuclear Information System (INIS)
Geng, Lisheng; Meng, Jie; Zhao, Qiang; Zou, Bingsong
2014-01-01
The recent past years have seen a remarkable progress towards a unified description of nonperturbative strong interaction phenomena based on the fundamental theory of the strong interaction, quantum chromodynamics, and effective field theories. The papers collected in this special issue focus on the recent progress in hadron and nuclear physics related to the chiral symmetry. They are written based on presentations at the Seventh International Symposium on Chiral Symmetry in Hadron and Nuclei which took place at Beihang University, Beijing, 27-30 October 2013. The sub-topics discussed in these papers include chiral and heavy-quark spin symmetry; chiral dynamics of few-body hadron systems; chiral symmetry and hadrons in a nuclear medium; chiral dynamics in nucleon-nucleon interaction and atomic nuclei; chiral symmetry in rotating nuclei; hadron structure and interactions; exotic hadrons, heavy flavor hadrons and nuclei; mesonic atoms and 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
Elusive active galactic nuclei
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.
Double charge exchange of pions on nuclei
International Nuclear Information System (INIS)
Dzhibuti, R.I.; Kezerashvili, R.Y.
1985-01-01
An analysis is made of the results of experimental and theoretical studies during the last ten years of a unique process: double charge exchange of pions on nuclei. On the one hand, the commissioning of meson factories and the use of new and more accurate experimental methods have led to the accumulation of rich and reliable material for not only light but also medium and heavy nuclei. On the other hand, the development and application of new microscopic theoretical approaches have led to a deepening of our ideas about the mechanism of these exotic reactions at low, intermediate, and high energies. The currently existing methods of theoretical investigation and all possible reaction mechanisms are considered. Particular attention is devoted to double charge exchange of pions on the lightest nuclei, for the theoretical description of which it is possible to use the well-developed methods for investigating few-particle systems. The experimental investigations of double-isobar analog and nonanalog transitions in the reaction of double charge exchange are systematized
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)
KEWPIE: a dynamical cascade code for decaying exited compound nuclei
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...
KEWPIE: A dynamical cascade code for decaying exited compound nuclei
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.
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
Modification of meson properties in the vicinty of nuclei
Directory of Open Access Journals (Sweden)
Filip Peter
2014-01-01
Full Text Available We suggest that modification of meson properties (lifetimes and branching ratios can occur due to the interaction of constituent quark magnetic moments with strong magnetic fields present in the close vicinity of nuclei. A superposition of (J =0 and (J =1, mz =0 particle-antiparticle quantum states (as observed for ortho-Positronium may occur also in the case of quarkonium states J/Ψ, ηc ϒ, ηb in heavy ion collisions. We speculate on possible modification of η(548 meson properties (related to C parity and CP violation in strong magnetic fields which are present in the vicinity of nuclei.
Study on decay of rare earth nuclei produced by fission
Energy Technology Data Exchange (ETDEWEB)
Kawade, Kiyoshi; Yamamoto, Hiroshi; Shibata, Michihiro; Asai, Masato [Nagoya Univ. (Japan); Tsukada, Kazuaki; Osa, Akihiko; Shinohara, Nobuo; Iimura, Hideki
1996-01-01
JAERI-ISOL utilizes charge particle induced fission by proton and heavy proton produced by the tandem type accelerator (JAERI). To study the decay mechanism and nuclei structure of neutron and excess nuclei produced by actinoid fission, JAERI-ISOL was improved by developing the multilayer target tank. So that, the intensity of mass separated ion beam increased enough to use. New 76.6 KeV {gamma}-ray with about 10s of half life was found in the preliminary experiment. (S.Y.)
Collective motions and band structures in A = 60 to 80, even--even nuclei
International Nuclear Information System (INIS)
Hamilton, J.H.; Robinson, R.L.; Ramayya, A.V.
1978-01-01
Evidence for and the theoretical understanding of the richness of the collective band structures as illustrated by at least seven bands seen in levels of 68 Ge, 74 Se are reviewed. The experimental data on even-even nuclei in the A = 60 to 80 region have now revealed a wide variety of collective bands with different structures. The even parity yrast cascades alone are seen to involve multiple collective structures. In addition to the ground-state bands, strong evidence is presented for both neutron and proton rotation-aligned bands built on the same orbital, (g 9 / 2 ) 2 , in one nucleus. Several other nuclei also show the crossing of RAL bands around the 8 + level in this region. Evidence continues to be strong experimentally and supported theoretically that there is some type of shape transition and shape coexistence occurring now both in the Ge and Se isotopes around N = 40. Negative parity bands with odd and even spins with very collective nature are seen in several nuclei to high spin. These bands seem best understood in the RAL model. Very collective bands with ΔI = 1, extending from 2 + to 9 + are seen with no rotation-alignment. The purity of these bands and their persistence to such high spin establish them as an independent collective mode which is best described as a gamma-type vibration band in a deformed nucleus. In addition to all of the above bands, new bands are seen in 76 Kr and 74 Se. The nature of these bands is not presently known. 56 references
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
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
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
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
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
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
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
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
Measurements of secondary neutrons producted from thick targets bombarded by heavy ions
Energy Technology Data Exchange (ETDEWEB)
Kurosawa, T.; Nakamura, T. [Tohoku Univ., Sendai (Japan). Cyclotron and Radioisotope Center; Nakao, N.; Shibata, T.; Uwamino, Y.; Nakanishi, N.; Fukumura, A.; Kumamoto, Y.
1997-03-01
We measured neutron angular and energy distributions from high energy heavy ions stopping in targets of carbon, aluminum, copper and lead at HIMAC. These spectra are much harder for the lighter target nucleus like carbon. This means that the momentum transfer in the forward direction from heavy ion beam to lighter nuclei is much higher than that to heavier nuclei. (author)
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
Isolation of Nuclei and Nucleoli.
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.
International Nuclear Information System (INIS)
Dover, C.B.
1991-06-01
We survey the field of strange particle nuclear physics, starting with the spectroscopy of strangeness S = -1 Λ hypernuclei, proceeding to an interpretation of recent data on S = -2 ΛΛ hypernuclear production and decay, and finishing with some speculations on the production of multi-strange nuclear composites (hypernuclei or ''strangelets'') in relativistic heavy ion collisions. 41 refs., 5 figs
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.)
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)
The neutron-proton pairing and the moments of inertia of the rare earth even-even nuclei
International Nuclear Information System (INIS)
Calik, A. E.; Deniz, C.; Gerceklioglu, M.
2009-01-01
In this study, the possible effect of the neutron-proton pairing interaction in the heavy nuclei has been investigated in the framework of the BCS model by making a simple approximation. This effect has been searched realistically by calculating the moments of inertia of deformed even-even nuclei. Calculations show that the moments of inertia of rare earth nuclei changed dramatically and approached the experimental values.
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)
Neutrinoless Double Beta Decay Matrix Elements in Light Nuclei
Energy Technology Data Exchange (ETDEWEB)
Pastore, S.; Carlson, J.; Cirigliano, V.; Dekens, W.; Mereghetti, E.; Wiringa, R. B.
2018-01-17
We present the first ab initio calculations of neutrinoless double-β decay matrix elements in A=6-12 nuclei using variational Monte Carlo wave functions obtained from the Argonne v_{18} two-nucleon potential and Illinois-7 three-nucleon interaction. We study both light Majorana neutrino exchange and potentials arising from a large class of multi-TeV mechanisms of lepton-number violation. Our results provide benchmarks to be used in testing many-body methods that can be extended to the heavy nuclei of experimental interest. In light nuclei we also study the impact of two-body short-range correlations and the use of different forms for the transition operators, such as those corresponding to different orders in chiral effective theory.
Beta decay rates of neutron-rich nuclei
Marketin, Tomislav; Huther, Lutz; Petković, Jelena; Paar, Nils; Martínez-Pinedo, Gabriel
2016-06-01
Heavy element nucleosynthesis models involve various properties of thousands of nuclei in order to simulate the intricate details of the process. By necessity, as most of these nuclei cannot be studied in a controlled environment, these models must rely on the nuclear structure models for input. Of all the properties, the beta-decay half-lives are one of the most important ones due to their direct impact on the resulting abundance distributions. In this study we present the results of a large-scale calculation based on the relativistic nuclear energy density functional, where both the allowed and the first-forbidden transitions are studied in more than 5000 neutron-rich nuclei. Aside from the astrophysical applications, the results of this calculation can also be employed in the modeling of the electron and antineutrino spectra from nuclear reactors.
Shell model Monte Carlo investigation of rare earth nuclei
International Nuclear Information System (INIS)
White, J. A.; Koonin, S. E.; Dean, D. J.
2000-01-01
We utilize the shell model Monte Carlo method to study the structure of rare earth nuclei. This work demonstrates the first systematic full oscillator shell with intruder calculations in such heavy nuclei. Exact solutions of a pairing plus quadrupole Hamiltonian are compared with the static path approximation in several dysprosium isotopes from A=152 to 162, including the odd mass A=153. Some comparisons are also made with Hartree-Fock-Bogoliubov results from Baranger and Kumar. Basic properties of these nuclei at various temperatures and spin are explored. These include energy, deformation, moments of inertia, pairing channel strengths, band crossing, and evolution of shell model occupation numbers. Exact level densities are also calculated and, in the case of 162 Dy, compared with experimental data. (c) 2000 The American Physical Society
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
Beta decay rates of neutron-rich nuclei
International Nuclear Information System (INIS)
Marketin, Tomislav; Petković, Jelena; Paar, Nils; Huther, Lutz; Martínez-Pinedo, Gabriel
2016-01-01
Heavy element nucleosynthesis models involve various properties of thousands of nuclei in order to simulate the intricate details of the process. By necessity, as most of these nuclei cannot be studied in a controlled environment, these models must rely on the nuclear structure models for input. Of all the properties, the beta-decay half-lives are one of the most important ones due to their direct impact on the resulting abundance distributions. In this study we present the results of a large-scale calculation based on the relativistic nuclear energy density functional, where both the allowed and the first-forbidden transitions are studied in more than 5000 neutron-rich nuclei. Aside from the astrophysical applications, the results of this calculation can also be employed in the modeling of the electron and antineutrino spectra from nuclear reactors.
Beta decay rates of neutron-rich nuclei
Energy Technology Data Exchange (ETDEWEB)
Marketin, Tomislav, E-mail: marketin@phy.hr; Petković, Jelena; Paar, Nils [Department of Physics, Faculty of Science, University of Zagreb, 10000 Zagreb (Croatia); Huther, Lutz [Institut für Kernphysik (Theoriezentrum), Technische Universität Darmstadt, 64289 Darmstadt (Germany); Martínez-Pinedo, Gabriel [Institut für Kernphysik (Theoriezentrum), Technische Universität Darmstadt, 64289 Darmstadt (Germany); GSI Helmholtzzentrum für Schwerioneneforschung, Planckstraße 1, 64291 Darmstadt (Germany)
2016-06-21
Heavy element nucleosynthesis models involve various properties of thousands of nuclei in order to simulate the intricate details of the process. By necessity, as most of these nuclei cannot be studied in a controlled environment, these models must rely on the nuclear structure models for input. Of all the properties, the beta-decay half-lives are one of the most important ones due to their direct impact on the resulting abundance distributions. In this study we present the results of a large-scale calculation based on the relativistic nuclear energy density functional, where both the allowed and the first-forbidden transitions are studied in more than 5000 neutron-rich nuclei. Aside from the astrophysical applications, the results of this calculation can also be employed in the modeling of the electron and antineutrino spectra from nuclear reactors.
Beta decay rates of neutron-rich nuclei
International Nuclear Information System (INIS)
Marketin, Tomislav; Huther, Lutz; Martínez-Pinedo, Gabriel
2015-01-01
Heavy element nucleosynthesis models involve various properties of thousands of nuclei in order to simulate the intricate details of the process. By necessity, as most of these nuclei cannot be studied in a controlled environment, these models must rely on the nuclear structure models for input. Of all the properties, the beta-decay half-lives are one of the most important ones due to their direct impact on the resulting abundance distributions. Currently, a single large-scale calculation is available based on a QRPA calculation with a schematic interaction on top of the Finite Range Droplet Model. In this study we present the results of a large-scale calculation based on the relativistic nuclear energy density functional, where both the allowed and the first-forbidden transitions are studied in more than 5000 neutron-rich nuclei
Beta decay rates of neutron-rich nuclei
Energy Technology Data Exchange (ETDEWEB)
Marketin, Tomislav, E-mail: marketin@phy.hr [Department of Physics, Faculty of Science, University of Zagreb, 10000 Zagreb (Croatia); Huther, Lutz [Institut für Kernphysik (Theoriezentrum), Technische Universität Darmstadt, 64289 Darmstadt (Germany); Martínez-Pinedo, Gabriel [Institut für Kernphysik (Theoriezentrum), Technische Universität Darmstadt, 64289 Darmstadt (Germany); GSI Helmholtzzentrum für Schwerioneneforschung, Planckstraße 1, 64291 Darmstadt (Germany)
2015-10-15
Heavy element nucleosynthesis models involve various properties of thousands of nuclei in order to simulate the intricate details of the process. By necessity, as most of these nuclei cannot be studied in a controlled environment, these models must rely on the nuclear structure models for input. Of all the properties, the beta-decay half-lives are one of the most important ones due to their direct impact on the resulting abundance distributions. Currently, a single large-scale calculation is available based on a QRPA calculation with a schematic interaction on top of the Finite Range Droplet Model. In this study we present the results of a large-scale calculation based on the relativistic nuclear energy density functional, where both the allowed and the first-forbidden transitions are studied in more than 5000 neutron-rich nuclei.
Maximal Electric Dipole Moments of Nuclei with Enhanced Schiff Moments
Ellis, John; Pilaftsis, Apostolos
2011-01-01
The electric dipole moments (EDMs) of heavy nuclei, such as 199Hg, 225Ra and 211Rn, can be enhanced by the Schiff moments induced by the presence of nearby parity-doublet states. Working within the framework of the maximally CP-violating and minimally flavour-violating (MCPMFV) version of the MSSM, we discuss the maximal values that such EDMs might attain, given the existing experimental constraints on the Thallium, neutron and Mercury EDMs. The maximal EDM values of the heavy nuclei are obtained with the help of a differential-geometrical approach proposed recently that enables the maxima of new CP-violating observables to be calculated exactly in the linear approximation. In the case of 225Ra, we find that its EDM may be as large as 6 to 50 x 10^{-27} e.cm.
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
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.)
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
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
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)
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)
Coupled SU(3) models of rotational states in nuclei and quasi-dynamical symmetry
International Nuclear Information System (INIS)
Thiamova, G.; Rowe, D. J.
2007-01-01
This contribution reports a first step towards the development of a model of low-lying nuclear collective states based on the progression from weak to strong coupling of a combination of systems in multiple SU(3) irreps. The motivation for such a model comes partly from the remarkable persistence of rotational structure observed experimentally and in many model calculations. This work considers the spectra obtainable by coupling just two SU(3) irreps by means of a quadrupole-quadrupole interaction. For a particular value of this interaction, the two irreps combine to form strongly-coupled irreps while for zero interaction the weakly-coupled results are mixtures of many such strongly-coupled irreps. A notable result is the persistence of the rotor character of the low-energy states for a wide range of the interaction strength. Also notable is the fact that, for very weak interaction strengths, the energy levels of the yrast band resemble those of a vibrational sequence while the B(E2) transition strengths remain close to those of an axially symmetric rotor, as observed in many nuclei. (Author)
Nuclei at high angular momentum, investigated with a Mini-Orange Spectrometer
International Nuclear Information System (INIS)
Feenstra, S.J.
1979-01-01
The multipolarity of continuum transitions following the reactions 160 Gd( 4 He,4n) 160 Dy and 146 Nd( 20 Ne,4n or 5n) 162 161 Yb has been deduced from experimental conversion coefficients. Conversion-electron spectra were measured with a Mini-Orange Spectrometer, while γ-ray spectra were recorded simultaneously with a NaI(Tl) detector or, at low energies (0.5 MeV), with a Ge(Li) detector. Both the electron and γ-ray spectra were measured in coincidence with discrete transitions in the product nuclei. The author derived the average conversion coefficient αsub(T) in three different energy regions. In the statistical region, above 1.5 MeV, the αsub(T) values are consistent with the multipolarity E1. In the Yrast region, between 0.7 and 1.5 MeV, αsub(T) approaches to the value expected for E2 radiation. Special attention has been given to the low-energy part of the continuum around 0.5 MeV. Recently, it has been proposed that low-energy continuum radiation has M1 multipolarity. The results of the author's conversion coefficient measurement do not support this suggestion. Especially in this low-energy region the coincidence requirement between continuum transitions and discrete lines appeared to be important. Without this requirement too high, misleading αsub(T) values, were obtained. (Auth.)
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)
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
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.
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.
Energy Technology Data Exchange (ETDEWEB)
Matuoka, Paula Fernanda Toledo
2016-07-01
In the present work, intermediate- and high-energy nuclear reactions involving heavy nuclei and protons were studied with the Monte Carlo CRISP (Rio - Ilheus - Sao Paulo Collaboration) model. The most relevant nuclear processes studied were intranuclear cascade and fission-evaporation competition. Preliminary studies showed fair agreement between CRISP model calculation and experimental data of multiplicity of evaporated neutrons (E < 20 MeV) from the p(1200 MeV) + {sup 208}Pb reaction and of spallation residues from the p(1000 MeV) + {sup 208}Pb reaction. The investigation of neutron multiplicity from proton-induced fission of {sup 232}Th up to 85 MeV showed that it was being overestimated by CRISP model; on the other hand, fission cross section were being underestimated. This behavior is due to limitations of the intranuclear cascade model for low-energies (around 50 MeV). The p(1200 MeV) + {sup 208}Pb reaction was selected for the study of a spallation neutron source. High-energy neutrons (E > 20 MeV) were emitted mostly in the intranuclear cascade stage, while evaporation presented larger neutron multiplicity. Fission cross section of 209 mb and spallation cross section of 1788 mb were calculated both in agreement with experimental data. The fission process resulted in a symmetric mass distribution. Another Monte Carlo code, MCNP, was used for radiation transport in order to understand the role of a spallation neutron source in a ADS (Accelerator Driven System) nuclear reactor. Initially, a PWR reactor was simulated to study the isotopic compositions in spent nuclear fuel. As a rst attempt, a spallation neutron source was adapted to an industrial size nuclear reactor. The results showed no evidence of incineration of transuranic elements and modifications were suggested. (author)
Heavy flavor production in nuclear collisions
Armesto-Pérez, Nestor; Capella, A; Pajares, C; Salgado, C A
2001-01-01
Heavy flavor production off nuclei is studied in the small x/sub F/ region of the produced heavy system. Corrections to the usually employed perturbative QCD factorization formula are considered in the framework of the Glauber-Gribov model. Transition from low to high energies is taken into account by using finite energy cutting rules. The low energy limit of the obtained results coincides with the probabilistic formula usually employed for quarkonium absorption. At finite energies both rescattering of the heavy flavor and corrections to nucleon parton densities inside nuclei appear, the latter also affecting lepton pair production. It turns out that at asymptotic energies both open heavy flavor and quarkonium are equally absorbed. The numerical differences between the results obtained with the probabilistic formula and the exact one are <20% up to LHC energies, and ~1/2% at SPS energies. (18 refs).
Nuclear physics research requirements for electron and heavy ion machines
International Nuclear Information System (INIS)
Vogt, E.
1983-03-01
There has been a great deal of interest in a variety of new machines intended to probe atomic nuclei for hadronic and quark aspects which lie beyond the familiar shell model view of nuclei. This paper gives the physics perspective within which the proposals for such machines have arisen and discusses the two classes of tools - high energy cw electron machines and relativistic heavy ion machines - which lie at opposite ends of the arsenal being gathered for the pursuit of QCD in nuclei. The electron machines present a reasoned analytic approach to the simplest systems and the heavy ion machines a major thrust for starting new physics in the quark-gluon sea
Pauli correlations in heavy-ion collisions at high energies
International Nuclear Information System (INIS)
Franco, V.; Nutt, W.T.
1977-01-01
The effects of short-range correlations on the Glauber expansion for nucleus-nucleus collisions are calculated using the Fermi gas model for nuclei. When the Pauli principle is neglected for collisions between heavy nuclei, calculation of the optical phase-shift function leads to non-unitary results and cross sections cannot be obtained. When Pauli correlations are included important cancellations in the optical phase-shift function are found which make possible the calculation of total and differential cross sections for heavy nuclei. (Auth.)
Superheavy nuclei in the relativistic mean-field theory
International Nuclear Information System (INIS)
Lalazissis, G.A.; Ring, P.; Gambhir, Y.K.
1996-01-01
We have carried out a study of superheavy nuclei in the framework of the relativistic mean-field theory. Relativistic Hartree-Bogoliubov (RHB) calculations have been performed for nuclei with large proton and neutron numbers. A finite-range pairing force of Gogny type has been used in the RHB calculations. The ground-state properties of very heavy nuclei with atomic numbers Z=100-114 and neutron numbers N=154-190 have been obtained. The results show that in addition to N=184 the neutron numbers N=160 and N=166 exhibit an extra stability as compared to their neighbors. For the case of protons the atomic number Z=106 is shown to demonstrate a closed-shell behavior in the region of well deformed nuclei about N=160. The proton number Z=114 also indicates a shell closure. Indications for a doubly magic character at Z=106 and N=160 are observed. Implications of shell closures on a possible synthesis of superheavy nuclei are discussed. (orig.)
Role of neutrons in the fusion of nuclei
International Nuclear Information System (INIS)
Zagrebaev, V. I.; Samarin, V. V.
2007-01-01
The problem of a quantum-mechanical description of a near-barrier fusion of heavy nuclei under conditions of a strong coupling of their relative motion to neutron degrees of freedom is studied. New mutually complementing efficient models employing the multidimensional time-dependent Schroedinger equation and methods for numerically solving the problems in question within these models are proposed. This makes it possible to study the evolution of wave functions for outer neutrons and to calculate nucleon transfer probabilities and occupation numbers for quasimolecular states over the entire energy range, including that of deep-subbarrier energies. It is shown that the valence-neutron wave functions extend over the volumes of both colliding nuclei before their surfaces come into contact and even before these nuclei overcome the Coulomb barrier (collectivization of outer nucleons). This gives rise to a substantial neutron-transfer effect on the fusion of nuclei and, in particular, to a sizable increase in the probability of subbarrier fusion for specific combinations of nuclei
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
Exotic nuclei arena in Japanese Hadron Project
International Nuclear Information System (INIS)
Nomura, T.
1990-04-01
A description is given on the radioactive beam facility proposed as one of the research arenas in Japanese Hadron Project. The facility consists of a 1 GeV proton linac, an isotope separator on-line (ISOL) and a series of heavy-ion (HI) linacs. Various exotic nuclei produced by 1 GeV proton beam mainly via spallation processes of a thick target, are mass-separated by the ISOL with a high mass-resolving power and are injected into the HI linac with the energy of 1 keV/u. The acceleration is made in three stages using different types of linacs, i.e., split-coaxial RFQ. Interdigital-H, and Alvarez, the maximum energy in each stage being 0.17, 1.4 and 6.5 MeV/u, respectively. A few examples of scientific interests realized in this facility will be briefly discussed. (author)