WorldWideScience

Sample records for backbending

  1. Backbends in directed percolation

    NARCIS (Netherlands)

    Roy, R.; Sarkar, A.; White, D.G.

    2001-01-01

    When directed percolation in a bond percolation process does not occur any path to innity on the open bonds will zigzag back and forth through the lattice Backbends are the portions of the zigzags that go against the percolation direction They are important in the physical problem of particle transp

  2. Quasi-dynamical symmetries in the backbending of chromium isotopes

    CERN Document Server

    Herrera, Raul A

    2016-01-01

    We examine the well-known backbending, or abrupt change in the moment of inertia along the yrast line, in $^{48,49,50}$Cr by decomposing configuration-interaction shell-model wavefunctions into group irreps, using the subgroups $L$ (total orbital angular momentum) and $S$ (total spin) of SU(2), and the groups SU(3) and SU(4). We see strong signatures of quasi-dynamical symmetries--the same or similar decomposition across members of a band--below the backbending, while quasi-dynamical symmetry is weaker above the bandbending.

  3. Quasi-dynamical symmetries in the backbending of chromium isotopes

    OpenAIRE

    Herrera, Raul A.; Johnson, Calvin W.

    2016-01-01

    We examine the well-known backbending, or abrupt change in the moment of inertia along the yrast line, in $^{48,49,50}$Cr by decomposing configuration-interaction shell-model wavefunctions into group irreps, using the subgroups $L$ (total orbital angular momentum) and $S$ (total spin) of SU(2), and the groups SU(3) and SU(4). We see strong signatures of quasi-dynamical symmetries--the same or similar decomposition across members of a band--below the backbending, while quasi-dynamical symmetry...

  4. 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.

  5. Relation between the critical spin and angular velocity of a nucleus immediately after backbending

    OpenAIRE

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

    2004-01-01

    In nonspherical nuclei at $J = J_c + 0$ the relationship between the angular momentum and angular velocity immediately after backbending is the same as in the limiting case $J - J_c\\to\\infty$. This indicates that there is a unique type of cancellation of the deviations from a rigid-body moment of inertia in the upper phase $J>J_c$. An integral relationship is found which expresses this cancellation quantitatively. This formula permits $J_c$ to be calculated for the rotational bands of the eve...

  6. Proton Orbital [541]1/2 and Backbending in 178W

    Institute of Scientific and Technical Information of China (English)

    WEI Zhi-Yuan; LIU Shu-Xin

    2008-01-01

    The microscopic mechanism of nine experimentally observed bands in 178W is investigated using the particle-number conserving method of the cranked shell model with monopole and quadrupole paring interactions.The experimental results,including the moments of inertia and angular momentum alignments of nine bands in 178W,are reproduced well by the particle-number conserving calculations,in which no free parameter is involved.Calculations demonstrate that occurrence of sharp backbending comes mainly from the contribution of high-j intruder orbitals vi13/2 or πh11/2 and their interference effect with orbitals near the Fermi surface.The w variation of the occupation probability of each cranked orbital and the contribution to moment of inertia from each cranked orbital are analyzed.

  7. Relation between the critical spin and angular velocity of a nucleus immediately after backbending

    Energy Technology Data Exchange (ETDEWEB)

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

    1979-05-01

    In nonspherical nuclei at J=J/sub c/+0 the relationship between the angular momentum and angular velocity immediately after backbending is the same as in the limiting case J-J/sub c/..-->..infinity. This indicates that there is a unique type of cancellation of the deviations from a rigid-body moment of inertia in the upper phase J>J/sub c/. An integral relationship is found which expresses this cancellation quantitatively. This formula permits J/sub c/ to be calculated for the rotational bands of the even-even nuclei studied and the results are in agreement with those obtained by other methods of locating the Curie point. For the ground state band of W/sup 170/ the cancellation of the reciprocals of the true and rigid-body moments of inertia can be verified directly. The condition for the stability of the rotation of a nonspherical nucleus is analyzed in the Appendix in close connection with the problem of a reasonable definition of the concept of a variable moment of inertia.

  8. Relation between the critical spin and angular velocity of a nucleus immediately after backbending

    CERN Document Server

    Nosov, V G

    1979-01-01

    In nonspherical nuclei at $J = J_c + 0$ the relationship between the angular momentum and angular velocity immediately after backbending is the same as in the limiting case $J - J_c\\to\\infty$. This indicates that there is a unique type of cancellation of the deviations from a rigid-body moment of inertia in the upper phase $J>J_c$. An integral relationship is found which expresses this cancellation quantitatively. This formula permits $J_c$ to be calculated for the rotational bands of the even-even nuclei studied and the results are in agreement with those obtained by other methods of locating the Curie point. For the ground state band of W$^{170}$ the cancellation of the reciprocals of the true and rigid-body moments of inertia can be verified directly. The condition for the stability of the rotation of a nonspherical nucleus is analyzed in the Appendix in close connection with the problem of a reasonable definition of the concept of a variable moment of inertia.

  9. Study of backbending phenomena in yrast bands of 120∼130Xe, 124∼130Ba with O(6) limit of IBM 1 containing three-body potential

    International Nuclear Information System (INIS)

    The Yrast band energy spectra of even-even nuclei 120∼130Xe and 124∼130Ba are calculated by using the O(6) limit of IBM 1 containing three-body potential. It shows that the backbending characteristics in the Yrast bands can be described fairly by O(6) + V3

  10. No anomaly of the B(E2) value around the backbend in sup 1 sup 3 sup 0 Ce

    CERN Document Server

    Li Guang Sheng; LiuXianGan; Zhang Lan Kuan; Wen Shu Xian; Wu Xiao Guang; Yuan Guan Jun; Weng Pei Kun; Li Sheng Gang; Yang Chun Xiang; Li Hua; Yang Li Ming; Zhu Sheng Jiang

    2002-01-01

    The lifetime measurements of the high-spin states in the yrast band of sup 1 sup 3 sup 0 Ce have been performed using the Doppler shift attenuation method in conjunction with the reaction sup 1 sup 1 sup 6 Sn( sup 1 sup 6 O, 2n) sup 1 sup 3 sup 0 Ce at a projectile energy of 73 MeV. The reduced transition probabilities B(E2) deduced from these measurements show a great reduction in the vicinity of the backbending region. The previously reported anomalously high B(E2) value was not observed in the present experiment. This result is in agreement with theoretical prediction based on a realistic nucleon-nucleon interaction

  11. Characterization of Backbending in Even-Even Isotopes of 164-174Hf and 154-164Dy Nuclei by a Modified Phenomenological Model

    Science.gov (United States)

    Najim, L. A.; Kheder, Malek. H.

    2013-07-01

    A modified phenomenological model is used to calculate nuclear energy levels and describe successfully the backbending of the moment of inertia for the ground state bands in even-even isotopes of Hf and Dy nuclei. The model is a combination of the Myers and Swiatecki model with variable moment inertia (VMI) model. Since the Myers and Swiatecki model has a deviation from experimental energies in which it takes into account pairing effect with constant moment of inertia, in the rotation of nuclei, the Coriolis force acts to de-pair the nucleons pair and align their angular momentum with nuclei total angular momentum, thus Coriolis force increasing and decrease the rotational energy. So, the moment of inertia varies with the angular momentum. Therefore, we modified this model by adding a term to make the moment of inertia vary with angular momentum in the same manner of the VMI model which has a term added to the rotational energy equation. The modified model fits remarkably with the experimental observation and other models in many cases with the use of few parameters especially in rotational nuclei regions similar to Hf and Dy nuclei.

  12. Quasiparticle and collective nucleon degrees of freedom in nuclei and its correlation in structure of Hf isotopes

    International Nuclear Information System (INIS)

    Structure of energy spectra and backbending phenomena of the isotope string of Hf with mass number between 162 and 170 have been investigated. Extend of SU(3)-limits of interacting boson model to allow a boson to break to form a quasiparticle pair, which can occupy h11/2 and i13/2 orbitals. The calculated energy levels, intensity of the electromagnetic transitions, including the ground state, β and γ band are in satisfactory agreement with observed values for the whole string of Hf isotopes. Backbending of the moment inertia of the yrast and β bands can be reproduced reasonably. Recently, very high spin states up to J=40 and a double backbending have been observed in some nuclei in rare-earth region. This phenomena might hopefully be interpreted by considering two or more bosons to break to form more quasiparticle pairs and make more bands crossing to form the double backbending

  13. Lifetimes of high-spin states in {sup 180-184}Pt

    Energy Technology Data Exchange (ETDEWEB)

    Carpenter, M.P.; Ahmad, I.; Crowell, B. [and others

    1995-08-01

    Over the past few years, lifetimes were measured, using the recoil distance method, to investigate shape-coexistence and shape transitions in the even mass {sup 182-186}Pt isotopes. In all three cases, one observes a sharp increase in the transition quadrupole moment, Q{sub t}, at low frequencies followed by a rapid and significant decline in the backbending region. It was shown that the initial increase in the Q{sub t} can be explained in terms of the mixing at low spins of two bands of very different deformation, and the decline in the backbending region is brought about by mixing between the ground and a two-quasiparticle band. No lifetime information exists for these nuclei above the backbend, and there is some contention whether or not the backbend is due to the alignment of h{sub 9/2} protons, i{sub 13/2} neutrons or the near simultaneous alignment of both. Nilsson-Strutinsky calculations indicate very different shapes for the nuclei after the backbend, depending on which orbitals align. Thus, lifetime information on the states above the backbend should help determine which interpretation is correct. In order to determine the lifetimes of states in the even mass {sup 180-184}Pt nuclei above the backbend, we performed a recent experiment at Gammasphere using a {sup 64}Ni beam on Pb backed Sn targets in order to populate the nucleus of interest via a 4n reaction. At the time of the experiment, thirty-six Ge detectors were available for use in Gammasphere and approximately 100 x 10{sup 6} 3-fold and higher events were taken for each nucleus. Currently, angle-sorted matrices were created from the data, and spectra representing the ground bands show well developed lineshapes for transitions above the backbend. A full lineshape analysis of the data will begin shortly.

  14. THE TWO-LEVEL MODEL AT FINITE-TEMPERATURE

    Energy Technology Data Exchange (ETDEWEB)

    Goodman, A.L.

    1980-07-01

    The finite-temperature HFB cranking equations are solved for the two-level model. The pair gap, moment of inertia and internal energy are determined as functions of spin and temperature. Thermal excitations and rotations collaborate to destroy the pair correlations. Raising the temperature eliminates the backbending effect and improves the HFB approximation.

  15. The relativistic consistent angular-momentum projected shell model study of the N=Z nucleus 52Fe

    Institute of Scientific and Technical Information of China (English)

    LI YanSong; LONG GuiLu

    2009-01-01

    The relativistic consistent angular-momentum projected shell model (RECAPS) is used in the study of the structure and electromagnetic transitions of the low-lying states in the N=Z nucleus 52Fe.The model calculations show a reasonably good agreement with the data.The backbending at 12+ is reproduced and the energy level structure suggests that neutron-proton interactions play important roles.

  16. The relativistic consistent angular-momentum projected shell model study of the N=Z nucleus 52Fe

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The relativistic consistent angular-momentum projected shell model(ReCAPS) is used in the study of the structure and electromagnetic transitions of the low-lying states in the N=Z nucleus 52Fe.The model calculations show a reasonably good agreement with the data.The backbending at 12+ is reproduced and the energy level structure suggests that neutron-proton interactions play important roles.

  17. Microscopic insight in the study of yrast bands in selenium isotopes

    Indian Academy of Sciences (India)

    Parvaiz Ahmad Dar; Sonia Verma; Rani Devi; S K Khosa

    2008-05-01

    The yrast bands of even-even selenium isotopes with = 68-78 are studied in the framework of projected shell model, by employing quadrupole plus monopole and quadrupole pairing force in the Hamiltonian. The oblate and prolate structures of the bands have been investigated. The yrast energies, backbending plots and reduced 2 transition probabilities and -factors are calculated and compared with the experimental data. The calculated results are in reasonably good agreement with the experiments.

  18. {Delta}I = 2 energy staggering in normal deformed dysprosium nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Riley, M.A.; Brown, T.B.; Archer, D.E. [Florida State Univ., Tallahassee, FL (United States)] [and others

    1996-12-31

    Very high spin states (I{ge}50{Dirac_h}) have been observed in {sup 155,156,157}Dy. The long regular band sequences, free from sharp backbending effects, observed in these dysprosium nuclei offer the possibility of investigating the occurence of any {Delta}I = 2 staggering in normal deformed nuclei. Employing the same analysis techniques as used in superdeformed nuclei, certain bands do indeed demonstrate an apparent staggering and this is discussed.

  19. Analysis of the experimental level scheme of {sup 61}Cu using computational technique

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Anuradha, E-mail: annu1gupta1@gmail.com; Verma, Preeti, E-mail: preetiverma130587@gmail.com [Research Scholar, Department of Physics and Electronics, University of Jammu, Jammu-180006 (India); Bharti, Arun, E-mail: arunbharti-2003@yahoo.co.in [Professor, Department of Physics and Electronics, University of Jammu, Jammu-180006 (India)

    2015-08-28

    The high-spin structure in {sup 61}Cu nucleus is studied in terms of effective two body interaction. In order to take into account the deformed BCS basis, the basis states are expanded in terms of the core eigenfunctions. Yrast band with some other bands havew been obtained and back-bending in moment of inertia has also been calculated and compared with the available experimental data for {sup 61}Cu nucleus. On comparing the available experimental as well as other theoretical data, it is found that the treatment with PSM provides a satisfactory explanation of the available data.

  20. Investigation of band structure of {sup 103,105}Rh using microscopic computational technique

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Amit, E-mail: akbcw2@gmail.com [Research Scholar, Department of Physics and Electronics, University of Jammu, Jammu-180006 (India); Singh, Suram, E-mail: suramsingh@gmail.com [Assistant Professor, Department of Physics Govt. Degree College, Kathua-184142 (India); Bharti, Arun, E-mail: arunbharti-2003@yahoo.co.in [Professor, Department of Physics and Electronics, University of Jammu, Jammu-180006 (India)

    2015-08-28

    The high-spin structure in {sup 61}Cu nucleus is studied in terms of effective two body interaction. In order to take into account the deformed BCS basis, the basis states are expanded in terms of the core eigenfunctions. Yrast band with some other bands havew been obtained and back-bending in moment of inertia has also been calculated and compared with the available experimental data for {sup 61}Cu nucleus. On comparing the available experimental as well as other theoretical data, it is found that the treatment with PSM provides a satisfactory explanation of the available data.

  1. Phenomenological anharmonic vibrational models description for the ground state band energies of even-even nuclei

    CERN Document Server

    Mansour, N A

    2003-01-01

    The results from the cubic polynomial (CP) formula of the square of the angular velocity and the nuclear moments of inertia are compared with those from the variable moment of inertia (VMI) model and the available experimental information on transition energies for yrast line in even-even nuclei. The evaluated model parameters lead to an excellent fit for all energy levels ( I approx 24). The calculated critical spin for backbending in the zeta - omega sup 2 plot is found to be in agreement with the experimental data. (author)

  2. Phenomenological description of ground state bands for doubly even plutonium-isotopes

    CERN Document Server

    Alsoraya, A M

    2002-01-01

    The energy levels of the ground state bands of even-even plutonium-isotopes are studied according to the variable moment of inertia (VMI), variable moment of inertia nuclear softness (VMINS) and nuclear softness (NS) models. In general, the NS3 model leads to more reasonable results than the others. The backbending phenomena in these were described and discussed. The calculations of the transition probabilities B(E2) show that the effect of addition of each neutron pair on the deformation parameter (BETA) is very small. Furthermore, the proton and neutron effective charges are found to be e sub = 0.48 eb and e-v =0.33 eb.

  3. Recent developments of the projected shell model based on many-body techniques

    Directory of Open Access Journals (Sweden)

    Sun Yang

    2015-01-01

    Full Text Available Recent developments of the projected shell model (PSM are summarized. Firstly, by using the Pfaffian algorithm, the multi-quasiparticle configuration space is expanded to include 6-quasiparticle states. The yrast band of 166Hf at very high spins is studied as an example, where the observed third back-bending in the moment of inertia is well reproduced and explained. Secondly, an angular-momentum projected generate coordinate method is developed based on PSM. The evolution of the low-lying states, including the second 0+ state, of the soft Gd, Dy, and Er isotopes to the well-deformed ones is calculated, and compared with experimental data.

  4. Study of nuclear structure of odd mass 119-127I nuclei in a phenomenological approach

    Science.gov (United States)

    Singh, Dhanvir; Gupta, Anuradha; Kumar, Amit; Sharma, Chetan; Singh, Suram; Bharti, Arun; Khosa, S. K.; Bhat, G. H.; Sheikh, J. A.

    2016-08-01

    By using the phenomenological approach of Projected Shell Model (PSM), the positive and negative-parity band structures of odd mass neutron-rich 119-127I nuclei have been studied with the deformed single-particle states generated by the standard Nilsson potential. For these isotopes, the band structures have been analyzed in terms of quasi-particles configurations. The phenomenon of backbending in moment of inertia is also studied in the present work. Besides this, the reduced transition probabilities, i.e. B (E 2) and B (M 1), are obtained from the PSM wavefunction for the first time for yrast bands of these isotopes.

  5. The behaviour of constrained caloric curves as ultimate signature of a phase transition for hot nuclei

    CERN Document Server

    Borderie, B; Rivet, M F; Raduta, Ad R; Bonnet, E; Bougault, R; Chbihi, A; Galichet, E; Guinet, D; Lautesse, Ph; Neindre, N Le; Lopez, O; Parlog, M; Rosato, E; Roy, R; Spadaccini, G; Vient, E; Vigilante, M

    2012-01-01

    Simulations based on experimental data obtained from multifragmenting quasifused nuclei produced in central 129Xe + natSn collisions have been used to deduce event by event freeze-out properties on the thermal excitation energy range 4-12 AMeV. From these properties and temperatures deduced from proton transverse momentum fluctuations constrained caloric curves have been built. At constant average volumes caloric curves exhibit a monotonous behaviour whereas for constrained pressures a backbending is observed. Such results support the existence of a first order phase transition for hot nuclei.

  6. Rotational spectra and parity splitting in nuclei with strong octupole correlations

    International Nuclear Information System (INIS)

    A formula is suggested to describe the energies of positive- and negative-parity states belonging to the ground-state alternating-parity rotational bands in nuclei with significant octupole correlations. The agreement with experimental data is quite good for actinide nuclei. This formula corresponds to the parity splitting from a one-dimensional potential well. It leads to a common moment of inertia for both parities at least for low angular momenta. At high angular momenta a slight difference in the moments of inertia is found, which is presumably due to backbending. ((orig.))

  7. Heating Effects in Interlayer Tunneling Spectroscopy of Bi2.1Sr1.4Ca1.5Cu2O8+δ as Inferred from Single Junction Methods

    Science.gov (United States)

    Kurter, C.; Zasadzinski, J. F.; Ozyuzer, L.; Hinks, D. G.; Gray, K. E.

    2009-03-01

    In order to study Joule-heating effects on small intrinsic Josephson junction (IJJ) stacks or mesas, we compare their current-voltage curves, I(V), with those of single junctions, both using Bi2.1Sr1.4Ca1.5Cu2O8+δ (Ca-Bi2212) intercalated by HgBr2. Even for small volume stacks with reduced dissipation by intercalation, there can be self-heating despite the absence of the commonly seen backbending of I(V). This conclusion is based on distinctive features of I(V) of intermediate size mesas which were absent in single junctions.

  8. Projected shell model study of neutron-deficient 122Ce

    Indian Academy of Sciences (India)

    Rani Devi; B D Sehgal; S K Khosa

    2006-09-01

    The observed excited states of 122Ce nucleus have been studied in the frame-work of projected shell model (PSM). The yrast band has been studied up to spin 26 ħ. The first band crossing has been predicted above a rotational frequency of 0.4 MeV/ħ that corresponds to first backbending. The calculation reproduces the experimentally observed ground state band up to spin 14ħ. The electromagnetic quantities, transition quadrupole moments and -factors are predicted and there is a need to measure these quantities experimentally.

  9. Constrained caloric curves and phase transition for hot nuclei

    CERN Document Server

    Borderie, Bernard; Rivet, M F; Raduta, Ad R; Ademard, G; Bonnet, E; Bougault, R; Chbihi, A; Frankland, J D; Galichet, E; Gruyer, D; Guinet, D; Lautesse, P; Neindre, N Le; Lopez, O; Marini, P; Parlog, M; Pawlowski, P; Rosato, E; Roy, R; Vigilante, M

    2013-01-01

    Simulations based on experimental data obtained from multifragmenting quasi-fused nuclei produced in central $^{129}$Xe + $^{nat}$Sn collisions have been used to deduce event by event freeze-out properties in the thermal excitation energy range 4-12 AMeV [Nucl. Phys. A809 (2008) 111]. From these properties and the temperatures deduced from proton transverse momentum fluctuations, constrained caloric curves have been built. At constant average volumes caloric curves exhibit a monotonic behaviour whereas for constrained pressures a backbending is observed. Such results support the existence of a first order phase transition for hot nuclei.

  10. Stretching the Spines of Gymnasts: A Review.

    Science.gov (United States)

    Sands, William A; McNeal, Jeni R; Penitente, Gabriella; Murray, Steven Ross; Nassar, Lawrence; Jemni, Monèm; Mizuguchi, Satoshi; Stone, Michael H

    2016-03-01

    Gymnastics is noted for involving highly specialized strength, power, agility and flexibility. Flexibility is perhaps the single greatest discriminator of gymnastics from other sports. The extreme ranges of motion achieved by gymnasts require long periods of training, often occupying more than a decade. Gymnasts also start training at an early age (particularly female gymnasts), and the effect of gymnastics training on these young athletes is poorly understood. One of the concerns of many gymnastics professionals is the training of the spine in hyperextension-the ubiquitous 'arch' seen in many gymnastics positions and movements. Training in spine hyperextension usually begins in early childhood through performance of a skill known as a back-bend. Does practising a back-bend and other hyperextension exercises harm young gymnasts? Current information on spine stretching among gymnasts indicates that, within reason, spine stretching does not appear to be an unusual threat to gymnasts' health. However, the paucity of information demands that further study be undertaken. PMID:26581832

  11. Effects of the quark-hadron phase transition on highly magnetized neutron stars

    Science.gov (United States)

    Franzon, B.; Gomes, R. O.; Schramm, S.

    2016-11-01

    The presence of quark-hadron phase transitions in neutron stars can be related to several interesting phenomena. In particular, previous calculations have shown that fast rotating neutron stars, when subjected to a quark-hadron phase transition in their interiors, could give rise to the backbending phenomenon characterized by a spin-up era. In this work, we use an equation of state composed of two phases, containing nucleons (and leptons) and quarks. The hadronic phase is described in a relativistic mean field formalism that takes many-body forces into account, and the quark phase is described by the MIT bag model with a vector interaction. Stationary and axisymmetric stellar models are obtained in a self-consistent way by solving numerically the Einstein-Maxwell equations by means of a pseudo-spectral method. As a result, we obtain the interesting backbending phenomenon for fast spinning neutron stars. More importantly, we show that a magnetic field, which is assumed to be axisymmetric and poloidal, can also be enhanced due to the phase transition from normal hadronic matter to quark matter on highly magnetized neutron stars. Therefore, in parallel to the spin-up era, classes of neutron stars endowed with strong magnetic fields may go through a `magnetic-up era' in their lives.

  12. Effects of the quark-hadron phase transition on highly magnetized neutron stars

    Science.gov (United States)

    Franzon, B.; Gomes, R. O.; Schramm, S.

    2016-08-01

    The presence of quark-hadron phase transitions in neutron stars can be related to several interesting phenomena. In particular, previous calculations have shown that fast rotating neutron stars, when subjected to a quark-hadron phase transition in their interiors, could give rise to the backbending phenomenon characterized by a spin-up era. In this work, we use an equation of state composed of two phases, containing nucleons (and leptons) and quarks. The hadronic phase is described in a relativistic mean field formalism that takes many-body forces into account, and the quark phase is described by the MIT bag model with a vector interaction. Stationary and axi-symmetric stellar models are obtained in a self-consistent way by solving numerically the Einstein-Maxwell equations by means of a pseudo-spectral method. As a result, we obtain the interesting backbending phenomenon for fast spinning neutron stars. More importantly, we show that a magnetic field, which is assumed to be axi-symmetric and poloidal, can also be enhanced due to the phase transition from normal hadronic matter to quark matter on highly magnetized neutron stars. Therefore, in parallel to the spin-up era, classes of neutron stars endowed with strong magnetic fields may go through a "magnetic-up era" in their lives.

  13. Two-quasiparticle and collective excitations in transitional {sup 108,110}Pd nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Lalkovski, S. [CSNSM IN2P3-CNRS and Universite Paris-Sud, 91405, Orsay (France); University of Sofia St. Kliment Ohridski, 1126, Sofia (Bulgaria); Minkova, A. [CSNSM IN2P3-CNRS and Universite Paris-Sud, 91405, Orsay (France); University of Sofia St. Kliment Ohridski, 1126, Sofia (Bulgaria); INRNE, Bulgarian Academy of Sciences, 1784, Sofia (Bulgaria); Porquet, M.G.; Bauchet, A.; Deloncle, I. [CSNSM IN2P3-CNRS and Universite Paris-Sud, 91405, Orsay (France); Astier, A.; Buforn, N.; Meyer, M.; Prevost, A.; Redon, N.; Stezowski, O. [IPNL, IN2P3-CNRS and Universite Claude Bernard, 69622, Villeurbanne Cedex (France); Donadille, L. [University of Birmingham, Birmingham (United Kingdom); Dorvaux, O.; Gall, B.P.J.; Schulz, N. [IReS, IN2P3-CNRS and Universite Louis Pasteur, 67037, Strasbourg (France); Lucas, R. [Commissariat a l' Energie Atomique, CEA/Saclay, DSM/DAPNIA/SPhN, 91191, Gif-sur-Yvette Cedex (France)

    2003-12-01

    High-spin states in {sup 108,110}Pd isotopes are studied by {gamma}-ray spectroscopy of heavy-ion-induced fission. The Pd isotopes are produced in the fission channel of the {sup 31}P+{sup 176}Yb reaction at beam energy 152 MeV. The prompt {gamma}-rays are detected with the EUROBALL4 multidetector array. The yrast states of {sup 108,110}Pd have been observed above the region of the first backbend. The level scheme of {sup 108}Pd was extended with a new negative-parity band. The yrast sequence in {sup 110}Pd is observed up to spin I=14{sup +} and negative-parity bands have also been identified. The backbending in these even-mass Pd isotopes is associated with the alignment of the neutron (h{sub 11/2}){sup 2} pair. The negative-parity states arise from two neutron configurations {nu}h{sub 11/2} x {nu}g{sub 7/2} and {nu}h{sub 11/2} x {nu}d{sub 5/2} and they are interpreted in the frame of two-quasiparticle+rotor model as semidecoupled bands. The observed experimental staggering in the {gamma}-bands of {sup 108,110}Pd supports the theoretical predictions for {gamma}-instability of their shapes. (orig.)

  14. Effects of the quark-hadron phase transition on highly magnetized neutron stars

    CERN Document Server

    Franzon, B; Schramm, S

    2016-01-01

    The presence of quark-hadron phase transitions in neutron stars can be related to several interesting phenomena. In particular, previous calculations have shown that fast rotating neutron stars, when subjected to a quark-hadron phase transition in their interiors, could give rise to the backbending phenomenon characterized by a spin-up era. In this work, we use an equation of state composed of two phases, containing nucleons (and leptons) and quarks. The hadronic phase is described in a relativistic mean field formalism that takes many-body forces into account, and the quark phase is described by the MIT bag model with a vector interaction. Stationary and axi-symmetric stellar models are obtained in a self-consistent way by solving numerically the Einstein-Maxwell equations by means of a pseudo-spectral method. As a result, we obtain the interesting backbending phenomenon for fast spinning neutron stars. More importantly, we show that a magnetic field, which is assumed to be axi-symmetric and poloidal, can al...

  15. High spin spectroscopy of 123Ba and alignment processes for A ≅ 120

    International Nuclear Information System (INIS)

    The level scheme of 123Ba has been extended. Bands based on the [523]7/2- and [402]5/2+ Nilsson configurations were established to spins 59/2 (67/2 tentatively) and 29/2, respectively. The first backbend in this region is found to be caused by the alignment of a pair of h11/2 protons. For the first time in this mass region there is evidence for a second crossing due to the alignment of an h11/2 neutron pair in a neutron h11/2 band. The experimental results are compared with self-consistent cranking calculations. A previous suggestion that large γ-deformation is needed to explain the observed bandheads is not supported. (orig.)

  16. Investigation of the two-quasiparticle bands in the doubly-odd nucleus 166Ta using a particle-number conserving cranked shell model

    Science.gov (United States)

    Zhang, ZhenHua

    2016-07-01

    The high-spin rotational properties of two-quasiparticle bands in the doubly-odd 166Ta are analyzed using the cranked shell model with pairing correlations treated by a particle-number conserving method, in which the blocking effects are taken into account exactly. The experimental moments of inertia and alignments and their variations with the rotational frequency hω are reproduced very well by the particle-number conserving calculations, which provides a reliable support to the configuration assignments in previous works for these bands. The backbendings in these two-quasiparticle bands are analyzed by the calculated occupation probabilities and the contributions of each orbital to the total angular momentum alignments. The moments of inertia and alignments for the Gallagher-Moszkowski partners of these observed two-quasiparticle rotational bands are also predicted.

  17. The evolution properties of even–even 100-110Pd nuclei

    International Nuclear Information System (INIS)

    The properties of the yrast states for 100-110Pd even–even (e–e) nuclei have been established. The relation between the moment of inertia 2ϑ/ℏ2 and the square of the rotational energy (ℏω)2 has been drawn to identify the back-bending that may occur at a certain state for each isotope. The relation between gamma-energy over spin Eγ/I as a function of spin I has been drawn to determine the evolution in each isotope ranging from vibration to rotational properties. The suitable limit in the interacting boson model IBM-1 has been used to calculate the yrast states for each isotope, which are then compared with the experimental results. (author)

  18. Cluster structure and collective behavior of the nucleus sup 4 sup 8 Cr

    CERN Document Server

    Sakuda, T

    2002-01-01

    The structure of the nucleus sup 4 sup 8 Cr was investigated by the sup 4 sup 0 Ca+alpha+alpha orthogonality condition model (OCM). The energy spectra, electromagnetic transitions, and spectroscopic factors for the alpha+ sup 4 sup 4 Ti and sup 8 Be+ sup 4 sup 0 Ca channels were calculated and are discussed herein. The observed energies and E2 transitions of the yrast band, which show collective behavior, were found to be well reproduced by the cluster model. Some exotic 2 alpha-cluster states with ''Ca-alpha-alpha''- and ''alpha-Ca-alpha''-like configurations are predicted near the 2 alpha threshold. The structures of the states were analyzed through the wave functions. The mechanism of backbending of the yrast band can be explained naturally in terms of the cluster-coupling scheme.

  19. Observational implications of a strong phase transition in the dense matter equation of state for the rotational evolution of neutron stars

    CERN Document Server

    Bejger, M; Haensel, P; Zdunik, J L; Fortin, M

    2016-01-01

    We explore the implications of a strong first-order phase transition region in the dense matter equation of state in the interiors of rotating neutron stars, and the resulting creation of two disjoint families of neutron-stars' configurations (the so-called high-mass twins). Rotating, axisymmetric and stationary stellar configurations are obtained numerically in the framework of general relativity, and their global parameters and stability are studied. The equation of state-induced instability divides stable neutron star configurations into two disjoint families: neutron stars (second family) and hybrid stars (third family), with an overlapping region in mass, the high-mass twin star region. These two regions are divided by an instability strip. Its existence has interesting astrophysical consequences for rotating neutron stars. We note that it provides a "natural" explanation for the rotational frequency cutoff in the observed distribution of neutron stars spins, and for the apparent lack of back-bending in ...

  20. Cluster structure and collective behavior of the nucleus 48Cr

    International Nuclear Information System (INIS)

    The structure of the nucleus 48Cr was investigated by the 40Ca+α+α orthogonality condition model (OCM). The energy spectra, electromagnetic transitions, and spectroscopic factors for the α+ 44Ti and 8Be+ 40Ca channels were calculated and are discussed herein. The observed energies and E2 transitions of the yrast band, which show collective behavior, were found to be well reproduced by the cluster model. Some exotic 2α-cluster states with ''Ca-α-α''- and ''α-Ca-α''-like configurations are predicted near the 2α threshold. The structures of the states were analyzed through the wave functions. The mechanism of backbending of the yrast band can be explained naturally in terms of the cluster-coupling scheme

  1. Investigation of the high-spin rotational properties of the proton emitter $^{113}$Cs using a particle-number conserving method

    CERN Document Server

    Zhang, Zhen-Hua

    2016-01-01

    The recently observed two high-spin rotational bands in the proton emitter $^{113}$Cs are investigated using the cranked shell model with pairing correlations treated by a particle-number conserving method, in which the Pauli blocking effects are taken into account exactly. By using the configuration assignments of band 1 ($\\pi 3/2^+[422], \\alpha = -1/2$) and band 2 ($\\pi 1/2^+[420], \\alpha = 1/2$), the experimental moments of inertia and quasiparticle alignments can be well reproduced by the present calculations, which in turn strongly support these configuration assignments. Furthermore, by analyzing the occupation probability $n_\\mu$ of each cranked Nilsson level near the Fermi surface and the contribution of each orbital to the angular momentum alignments, the backbending mechanism of these two bands is also investigated.

  2. High spin levels in 62Zn, 64Zn, 66Zn, and 68Zn

    International Nuclear Information System (INIS)

    Investigation by in-beam gamma spectroscopy of high-spin states in the even zinc isotopes has been made using the Ni(α,2nγ)Zn reactions at Esub(α) approximately equal to 30MeV for 62Zn, 64Zn and 66Zn, and the 65Cu(α,pγ) reaction at Esub(α) approximately equal to 18MeV for 68Zn. The high-spin states feeding by varying the incident particles: p,3He,α,12C is discussed. It is pointed out that the gsub(9/2) orbital plays an important role in the structure of the high-spin states. The variation of the inertia momentum throughout the yrast line shows a backbending behavior and a shape transition associated to the occurence, for J>6, of rotational states is speculated

  3. Investigation of the two-quasiparticle bands in the doubly-odd nucleus $^{166}$Ta using a particle-number conserving cranked shell model

    CERN Document Server

    Zhang, Zhen-Hua

    2016-01-01

    The high-spin rotational properties of two-quasiparticle bands in the doubly-odd ${}^{166}$Ta are analyzed using the cranked shell model with pairing correlations treated by a particle-number conserving method, in which the blocking effects are taken into account exactly. The experimental moments of inertia and alignments and their variations with the rotational frequency $\\hbar\\omega$ are reproduced very well by the particle-number conserving calculations, which provides a reliable support to the configuration assignments in previous works for these bands. The backbendings in these two-quasiparticle bands are analyzed by the calculated occupation probabilities and the contributions of each orbital to the total angular momentum alignments. The moments of inertia and alignments for the Gallagher-Moszkowski partners of these observed two-quasiparticle rotational bands are also predicted.

  4. Experimental and theoretical investigation of anomalous behavior in rotational bands at high spin

    International Nuclear Information System (INIS)

    High spin states of the barium nuclei have been investigated via the 114Cd(16O,4n)126Ba, 120Sn(12C,4n)128Ba and 124Sn(12C,4n)132Ba reactions. The even spin positive parity yrast band in 126Ba has been excited up to the 16+, and possibly the 18+ state. In addition, another strongly excited band was excited with spins and parities: 7-, 9-, 11-, 13- and 15-. In 128Ba, the even spin positive parity band has been excited up to the 12+ state. Backbending seems to begin at the 12+ state. Two-quasiparticles-plus-rotor bandmixing calculations have been performed in order to explain the backbending and the anomalous negative parity bands observed in 126128Ba and several other nuclei. The test case of 68156Er88 was studied in detail. Good agreement with experimental excitation energies was obtained. The E2 transition rates between the negative parity yrast states were estimated for 156Er. Strongly enhanced rates are found within the states of odd spin, and within the state of even spin. The values of the g-factors were also estimated for the two-quasineutron yrast states in 156Er, showing considerable deviations from the rotational values. The calculation was applied, with very similar results to 56126Ba70. Reasonable fits to the excitation energies were obtained. The case of 46104Pd58 was considered, and very similar results were obtained. The nucleus 80192Hg112 was also studied. No reasonable fit was obtained for the negative parity states. The above evidence suggests that decoupling effects are responsible for the anomalous high spin behavior of the nuclei considered

  5. Spectral property and its shape transition on 72-84Kr isotopes in microscopic core plus two-quasiparticle approach

    Institute of Scientific and Technical Information of China (English)

    石筑一; 赵行知; 童红

    2003-01-01

    By using a microscopic sdIBM-2-+2q.p. approach, the levels of the ground-band, γ-band and partial two-quasi-particle bands for 72-84Kr isotopes are calculated. The data obtained are in good agreement with the recent experi-mental results, and successfully reproduce the nuclear shape phase transition of 72-84Kr isotopes at zero temperature.The ground-state band is described successfully up to Jπ=18+ and Ex=10.0MeV. Based on this model, the alignedrequisite minimum energy has been deduced. The theoretical calculations indicate that no distinct change of nuclearstates is caused by the abruptly broken pair of a boson, and predict that the first backbending of Kr isotopes may be theresult of aligning of two quasi-neutrons in orbit g9/2, which gains the new experimental support of the measurementsof g factors in the 78-86Kr isotopes.

  6. Rotational population patterns and searches for the nuclear SQUID (Superconducting Quantum Interference Device)

    International Nuclear Information System (INIS)

    This paper presents new theoretical results for rotational population patterns in the nuclear SQUID effect. (The term nuclear SQUID is in analogy to the solid-state Superconducting Quantum Interference Devices.) The SQUID effect is an interesting new twist to an old quest to understand Coriolis anti-pairing (CAP) effects in nuclear rotational bands. Two-neutron transfer reaction cross sections among high-spin states have long been touted as more specific CAP probes than other nuclear properties. Heavy projectiles like Sn or Pb generally are recommended to pump the deformed nucleus to as high spin as possible for transfer. The interference and sign reversal of 2n transfer amplitudes at high spin, as predicted in the early SQUID work imposes the difficult requirement of Coulomb pumping to near back-bending spins at closest approach. For Pb on rare earths we find a dramatic departure from sudden-approximation, so that the population depression occurs as low as final spin 10h. 14 refs., 8 figs

  7. U(5) symmetry of even {sup 96,98}Ru isotopes under the framework of interacting Boson model (IBM-1)

    Energy Technology Data Exchange (ETDEWEB)

    Sharrad, Fadhil I.; Ahmed, A.S. [Department of Physics, College of Science, Kerbala University, Karbala (Iraq); Hossain, I., E-mail: mihossain@kau.edu.sa [Department of Physics, Rabigh College of Science and Arts, King Abdulaziz University, Rabigh (Saudi Arabia); Ahmed, I.M. [Department of Physics, College of Education, Mosul University, Mosul (Iraq); Abdullah, Hewa Y. [Department of Physics, College of Science Education, Salahaddin University, Erbil, KRG (Iraq); Ahmad, S.T. [Department of Physics, Faculty of Science, Koya University, Koya, KRG (Iraq)

    2015-06-15

    In this paper, the yrast bands of the even {sup 96,98}Ru isotopes are studied within the framework of the interacting boson model-1 (IBM-1), using the MATLAB computer code (IBM-1.Mat). The theoretical energy levels are obtained for the {sup 96,98}Ru isotopes, with neutron numbers 52 and 54, up to spin-parity 16{sup +} and 12{sup +}, respectively. The ratio of the excitation energies of the first 4{sup +} to the first 2{sup +} excited states (R{sub 4/2}), the backbending curves and the potential energy surfaces are also calculated. The calculated and experimental R{sub 4/2} values show that the {sup 96,98}Ru nuclei have U(5) dynamic symmetry. The calculated energies of the yrast states are compared with experimental results and they are shown to be in good agreement with the data. The contour plots of the potential energy surfaces show two interesting nuclei having a slightly oblate but almost spherical vibrator-like character. (author)

  8. Rotating neutron stars with exotic cores: masses, radii, stability

    CERN Document Server

    Haensel, P; Fortin, M; Zdunik, J L

    2016-01-01

    A set of theoretical mass-radius relations for rigidly rotating neutron stars with exotic cores, obtained in various theories of dense matter, is reviewed. Two basic observational constraints are used: the largest measured rotation frequency is 716 Hz and the maximum measured mass is $2\\;{\\rm M}_\\odot$. Present status of measuring the radii of neutron stars is described. The theory of rigidly rotating stars in general relativity is reviewed and limitations of the slow rotation approximation are pointed out. Mass-radius relations for rotating neutron stars with hyperon and quark cores are illustrated using several models. Problems related to the non-uniqueness of the crust-core matching are mentioned. Limits on rigid rotation resulting from the mass-shedding instability and the instability with respect to the axisymmetric perturbations are summarized. The problem of instabilities and of the back-bending phenomenon are discussed in detail. Metastability and instability of a neutron star core in the case of a fi...

  9. Characteristics of collectivity along the yrast line in even-even tungsten isotopes

    Science.gov (United States)

    Yang, Qiong; Wang, Hua-Lei; Liu, Min-Liang; Xu, Fu-Rong

    2016-08-01

    The collective nature of high-spin yrast states in even-even W-190160 isotopes was systematically investigated by means of pairing self-consistent Woods-Saxon-Strutinsky calculations using the total Routhian surface approach in (β2,γ ,β4) deformation space. The calculated ground-state deformations are consistent with previous calculations and available experimental data. The deformation energy curves are presented to show the shape and softness evolutions, in particular in the triaxial direction. The backbending or upbending behavior in moment of inertia is attributed to band crossing. It is found that the neutron rotation alignment is preferred for most of the W isotopes (e.g., in W-180164), while in other nuclei the competition between the neutron and proton alignments may occur, even the proton alignment is favored in the very neutron-deficient nucleus 160W. In addition, the evolution and transition between vibrational and rotational collective modes along the yrast line are investigated on the basis of the new centipedelike E-GOS (E-Gamma Over Spin) curves introduced by us, which to some extent explains the existing differences (e.g., in the moment of inertia) between theory and experiment.

  10. High spin levels in 66Ga, 68Ga, 70Ga and 68Ge, 70Ge, 72Ge via fusion evaporation reactions induced by α-particles

    International Nuclear Information System (INIS)

    The high spin (J70Ga all the members (except the 3- one) of the (πpsub(3/2), νgsub(9/2)) configuration have been identified, in addition with the (πfsub(5/2), νgsub(9/2))sub(7-) and (πgsub(9/2), νgsub(9/2))sub(9+) states. In 66Ga and 68Ga most of the levels with J>7 ca be described as a result of maximum coupling of a gsub(9/2) neutron with the odd Ga core. Thus the (πgsub(9/2), νgsub(9/2))sub(9+) states have been safely located. In the same way the even Ge, the backbending effect at the Jsup(π)=8+ state is less and less pronouced from the 68Ge to the 72Ge; that can be explained by the (νgsub(9/2))2sub(8+) configuration of this state, so that the 8+→6+ γ-transition is more and more allowed with increasing N, i.e. as the νgsub(9/2) shell acts more and more in the lower yrast levels Jsup(π)=0+, 2+, 4+, 6+ configurations

  11. Cold transfer between deformed, Coulomb excited nuclei; Kalter Transfer zwischen deformierten, Coulomb-angeregten Kernen

    Energy Technology Data Exchange (ETDEWEB)

    Bauer, H.

    1998-12-31

    The scattering system {sup 162}Dy {yields} {sup 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 {gamma}-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 {sup 162}Dy has been analyzed. The gross properties of the measured population probabilities could be interpreted in a simple band mixing model. (orig.)

  12. In-beam studies of high-spin states of actinide nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Stoyer, M.A. (Lawrence Berkeley Lab., CA (USA). Nuclear Science Div. California Univ., Berkeley, CA (USA). Dept. of Chemistry)

    1990-11-15

    High-spin states in the actinides have been studied using Coulomb- excitation, inelastic excitation reactions, and one-neutron transfer reactions. Experimental data are presented for states in {sup 232}U, {sup 233}U, {sup 234}U, {sup 235}U, {sup 238}Pu and {sup 239}Pu from a variety of reactions. Energy levels, moments-of-inertia, aligned angular momentum, Routhians, gamma-ray intensities, and cross-sections are presented for most cases. Additional spectroscopic information (magnetic moments, M{sub 1}/E{sub 2} mixing ratios, and g-factors) is presented for {sup 233}U. One- and two-neutron transfer reaction mechanisms and the possibility of band crossings (backbending) are discussed. A discussion of odd-A band fitting and Cranking calculations is presented to aid in the interpretation of rotational energy levels and alignment. In addition, several theoretical calculations of rotational populations for inelastic excitation and neutron transfer are compared to the data. Intratheory comparisons between the Sudden Approximation, Semi-Classical, and Alder-Winther-DeBoer methods are made. In connection with the theory development, the possible signature for the nuclear SQUID effect is discussed. 98 refs., 61 figs., 21 tabs.

  13. Studies of normal deformation in {sup 151}Dy

    Energy Technology Data Exchange (ETDEWEB)

    Nisius, D.; Janssens, R.V.F.; Crowell, B. [and others

    1995-08-01

    The wealth of data collected in the study of superdeformation in {sup 151}Dy allowed for new information to be obtained on the normally deformed structures in this nucleus. At high spin several new yrast states have been identified for the first time. They were associated with single-particle excitations. Surprisingly, a sequence was identified with energy spacings characteristic of a rotational band of normal ({beta}2 {approximately} 0.2) deformation. The bandhead spin appears to be 15/2{sup -} and the levels extend up to a spin of 87/2{sup -}. A clear backbend is present at intermediate spins. While a similar band based on a bandhead of 6{sup +} is known in {sup 152}Dy, calculations suggest that this collective prolate band should not be seen in {sup 151}Dy. In the experiment described earlier in this report that is aimed at determining the deformations associated with the SD bands in this nucleus and {sup 152}Dy, the deformation associated with this band will be determined. This will provide further insight into the origin of this band.

  14. Rotating neutron stars with exotic cores: masses, radii, stability

    International Nuclear Information System (INIS)

    A set of theoretical mass-radius relations for rigidly rotating neutron stars with exotic cores, obtained in various theories of dense matter, is reviewed. Two basic observational constraints are used: the largest measured rotation frequency (716Hz) and the maximum measured mass (2M CircleDot). The present status of measuring the radii of neutron stars is described. The theory of rigidly rotating stars in general relativity is reviewed and limitations of the slow rotation approximation are pointed out. Mass-radius relations for rotating neutron stars with hyperon and quark cores are illustrated using several models. Problems related to the non-uniqueness of the crust-core matching are mentioned. Limits on rigid rotation resulting from the mass-shedding instability and the instability with respect to the axisymmetric perturbations are summarized. The problem of instabilities and of the back-bending phenomenon are discussed in detail. Metastability and instability of a neutron star core in the case of a first-order phase transition, both between pure phases, and into a mixed-phase state, are reviewed. The case of two disjoint families (branches) of rotating neutron stars is discussed and generic features of neutron-star families and of core-quakes triggered by the instabilities are considered. (orig.)

  15. Rotating neutron stars with exotic cores: masses, radii, stability

    Energy Technology Data Exchange (ETDEWEB)

    Haensel, P.; Bejger, M.; Fortin, M.; Zdunik, L. [Polish Academy of Sciences, N. Copernicus Astronomical Center, Warszawa (Poland)

    2016-03-15

    A set of theoretical mass-radius relations for rigidly rotating neutron stars with exotic cores, obtained in various theories of dense matter, is reviewed. Two basic observational constraints are used: the largest measured rotation frequency (716Hz) and the maximum measured mass (2M {sub CircleDot}). The present status of measuring the radii of neutron stars is described. The theory of rigidly rotating stars in general relativity is reviewed and limitations of the slow rotation approximation are pointed out. Mass-radius relations for rotating neutron stars with hyperon and quark cores are illustrated using several models. Problems related to the non-uniqueness of the crust-core matching are mentioned. Limits on rigid rotation resulting from the mass-shedding instability and the instability with respect to the axisymmetric perturbations are summarized. The problem of instabilities and of the back-bending phenomenon are discussed in detail. Metastability and instability of a neutron star core in the case of a first-order phase transition, both between pure phases, and into a mixed-phase state, are reviewed. The case of two disjoint families (branches) of rotating neutron stars is discussed and generic features of neutron-star families and of core-quakes triggered by the instabilities are considered. (orig.)

  16. U(5) symmetry of even 96,98Ru isotopes under the framework of interacting Boson model (IBM-1)

    International Nuclear Information System (INIS)

    In this paper, the yrast bands of the even 96,98Ru isotopes are studied within the framework of the interacting boson model-1 (IBM-1), using the MATLAB computer code (IBM-1.Mat). The theoretical energy levels are obtained for the 96,98Ru isotopes, with neutron numbers 52 and 54, up to spin-parity 16+ and 12+, respectively. The ratio of the excitation energies of the first 4+ to the first 2+ excited states (R4/2), the backbending curves and the potential energy surfaces are also calculated. The calculated and experimental R4/2 values show that the 96,98Ru nuclei have U(5) dynamic symmetry. The calculated energies of the yrast states are compared with experimental results and they are shown to be in good agreement with the data. The contour plots of the potential energy surfaces show two interesting nuclei having a slightly oblate but almost spherical vibrator-like character. (author)

  17. Yoga for Persistent Fatigue in Breast Cancer Survivors: Results of a Pilot Study

    Directory of Open Access Journals (Sweden)

    Julienne E. Bower

    2011-01-01

    Full Text Available Approximately one-third of breast cancer survivors experiences persistent fatigue for months or years after successful treatment completion. There is a lack of evidence-based treatments for cancer-related fatigue, particularly among cancer survivors. This single-arm pilot study evaluated the feasibility and preliminary efficacy of a yoga intervention for fatigued breast cancer survivors based on the Iyengar tradition. Iyengar yoga prescribes specific poses for individuals with specific medical problems and conditions; this trial emphasized postures believed to be effective for reducing fatigue among breast cancer survivors, including inversions and backbends performed with the support of props. Twelve women were enrolled in the trial, and 11 completed the full 12-week course of treatment. There was a significant improvement in fatigue scores from pre- to post-intervention that was maintained at the 3-month post-intervention followup. Significant improvements were also observed in measures of physical function, depressed mood, and quality of life. These results support the acceptability of this intervention and suggest that it may have beneficial effects on persistent post-treatment fatigue. However, results require replication in a larger randomized controlled trial.

  18. Toward extremes of angular momentum: Application of the Pfaffian algorithm in realistic calculations

    CERN Document Server

    Wang, Long-Jun; Mizusaki, Takahiro; Oi, Makito; Sun, Yang

    2014-01-01

    In a calculation of rotated matrix elements with angular momentum projection, the generalized Wick's theorem may encounter a practical problem of combinatorial complexity when the configurations have more than four quasi-particles (qps). The problem can be solved by employing the Pfaffian algorithm generally applicable to calculations of matrix elements for Hartree-Fock-Bogoliubov states with any number of qps. This breakthrough in many-body techniques enables studies of high-spin states in a shell-model framework. As the first application of the Pfaffian algorithm, the configuration space of the Projected Shell Model is expanded to include 6-qp states for both positive and negative parities. Taking $^{166}$Hf as an example, we show that 6-qp states become the main configuration of the yrast band beyond spin $I \\approx 34\\hbar$, which explains the observed third back-bending in moment of inertia. Structures of multi-qp high-$K$ isomers in $^{176}$Hf are analyzed as another example.

  19. Measurement of lifetimes of high spin states in the N = 106 nuclei {sup 183}Ir and {sup 182}Os

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, I.; Blumenthal, D.; Carpenter, M.P. [and others

    1995-08-01

    Lifetimes of high spin states in the isotones {sup 183}Ir and {sup 182}Os were measured using the Notre Dame plunger device in conjunction with the Argonne Notre Dame {gamma}-ray facility. The aim of these measurements was to determine the deformation-driving properties of the h{sub 9/2} proton intruder orbital by comparing the values of the intrinsic quadrupole moments in the ground state bands in the odd-mass Ir nucleus and the even-even Os core. Levels in these nuclei were populated by the {sup 150}Nd ({sup 37}Cl,4n) and {sup 150}Nd ({sup 36}S,4n) reactions using a {sup 37}Cl beam of 169 MeV and 164-Mev {sup 36}S beam. The {sup 150}Nd target was 0.9-g/cm{sup 2} thick and was prepared by evaporating enriched {sup 150}Nd onto a stretched 1.5-mg/cm{sup 2} gold foil. The target was covered with a layer of a 60-{mu}g/cm{sup 2} Au to prevent its oxidation. Gamma-ray spectra were accumulated for approximately 4 hours for each target-stopper distance. Data were collected for 20 target-stopper distances ranging from 16 {mu}m to 10.4 mm. Preliminary analysis indicates that it will be possible to extract the lifetimes of the levels in the yrast bands up to and including part of the backbending region with sufficient accuracy. Detailed analysis of the data is in progress.

  20. Self-coherent Hartree-Fock theory and the microscopic symmetries of the nucleus; Theorie autocoherente de Hartree-Fock et les symetries microscopiques du noyau

    Energy Technology Data Exchange (ETDEWEB)

    Bouguettoucha, A.

    1996-06-14

    A possible effects of the C{sub 4}-symmetry in the superdeformed nuclei of the A {approx}150 mass range has been studied microscopically using cranking Strutinsky method with the deformed Woods-Saxon potential and the Hartree-Fock approach with the Skyrme interaction. If the existence of such a symmetry is judged by the moments Q{sub 44}, the results of the calculation indicate a very weak effect of this kind. Four new superdeformed bands in the {sup 148}Gd nucleus have been studied in reaction to the recent experimental observations (Eurogam Phase 2): a backbending has been tentatively observed at very high rotational frequency in the third excited band. One of the other bands exhibits a J{sup (2)} moment very similar to that of the yrast band in {sup 152}Dy, and this is the first example of identical bands which differ by four mass units. Calculations with the methods mentioned above have been used to analyse the band structure in terms of the nucleonic configurations. Calculation have been performed for some nuclear configurations predicted to involve the exotic octupole deformations (Y{sub 30-}`pear shapes`; Y{sub 31-}`banana mode`; Y{sub 32-}`T{sub d}-symmetry` and Y{sub 33-}`C{sub 3}-symmetry`). While the previous calculations based on the Strutinsky method could not treat the coupling between those modes, the Hartree-Fock approach allows to see for the first time in which propositions the various modes couple. (author). 116 refs.

  1. The vibration states of the Skyrme model

    International Nuclear Information System (INIS)

    In the paper an algebraic method for the construction of the collective Hamiltonian of the Skyrme model is treated. The Skyrme model has some phenomenological success in describing the static properties of nucleon and their interactions. The vibration spectra in the framework of the subgroup SU(5) have been discussed. Exploiting the related symmetry group it is possible to obtain the simple analytic expressions for the eigenvalues of boson Hamiltonian and for intraband transition matrix elements as well as for side feeding from one band to the other. Back-bending occurs naturally as the crossing of two bands and it can be predicted from the relative spacing of the low excited states. The algebraic properties of collective variables lead to a new quantum number N which implies in the boson representation the maximum number of phonons contained in vibrational states. Because the boson-boson interaction in SU(5) invariant Hamiltonian splits the degeneracy of the multiplets, this limits describes an anharmonic vibrator. It should be noted, we describe finite dimensional system in contrast with the geometrical description in which N→∞. It is worth noting that the knowledge of the invariance properties of Hamiltonian provides directly a solution to the eigenvalue problem. The transformation into intrinsic frame of reference has been performed explicitly. Thus, the formulae for the potential energy, the quadrupole moments are obtained as well as the spectroscopic factors for 0+ state excitation in the two nucleon transfer reactions. The proposed collective Hamiltonian is applied to the transformational nuclei Sm, Gd and Dy. The agreement between the experimental data and the theoretical description is good

  2. Orogenic plateau magmatism of the Arabia-Eurasia collision zone

    Science.gov (United States)

    Allen, M. B.; Neill, I.; Kheirkhah, M.; van Hunen, J.; Davidson, J. P.; Meliksetian, Kh.; Emami, M. H.

    2012-04-01

    generally applicable as melt triggers. Enigmatic lavas are erupted over the thick lithosphere of Kurdistan Province, Iran. These alkali basalts and basanites have the chemical characteristics of small degree (<1%) melts in the garnet stability field. Most possess supra-subduction zone chemistry (La/Nb = 1-3), but this signature is highly variable. Similar La/Nb variability occurs in the basic lavas of Damavand volcano in the Alborz Mountains of northern Iran. Modelling suggests the depletion of residual amphibole during the progression of partial melting can explain the observed La/Nb range. This melting may occur as the result of lithospheric thickening. At depths of ~90 km, amphibole-bearing peridotite crosses an experimentally-determined "backbend" in its solidus. Melting can continue while the source remains hydrated. Such "compression" melting may apply to parts of other orogenic plateaux, including Tibet.

  3. Cyclortron-based nuclear science. Progress in research, April 1, 1982-March 31, 1983

    International Nuclear Information System (INIS)

    This report contains descriptions of the activities of the research programs at the Institute and the progress on construction of the new cyclotron facility over the past year. A wide variety of both experimental and theoretical programs were underway and brief descriptions of recent progress in some areas of current interest are given. The first measurement of parity violation in the H(p,p) reaction has been completed at Ep = 47 MeV. Measurements of the vector and tensor analyzing powers A/sub y/(180), A/sub yy/180), and Z/sub zz/(00) for the 2H(d,n) 3He, 2H(d,n)X and 1H(d,n)2p reactions at E/sub d/ = 46 MeV have been performed. The giant monopole resonance has been identified in 28Si at E/sub x/ = 55/A sup 1/3/ MeV by small angle inelastic alpha scattering measurements. Further evidence for the proton character of levels causing second backbending in the Yb region has been obtained through the use of in-beam spectroscopy combined with a total multiplicity filter. Measurements of the energy spectra of H and He isotopes from the fragmentation of 320 MeV 10B projectiles in the system 10B + 181Ta lead to low momentum widths sigma/0 = 54 MeV/c) suggesting a rapid transition in momentum width between 32 and 43 MeV/nucleon. Evidence for enhanced fragment spins and shell effects in heavy-ion induced fission have been obtained. High resolution fluorine x-ray spectra of ionic solids excited by 80 MeV Ar ions have provided evidence of rapid electron transfer from the outer levels of surrounding atoms to energy matched high n states of highly ionized fluorine target atoms. In theoretical efforts, the transition from fusion and deep inelastic reactions at low energies to spectator/participant and fireball pictures at high energies has been clarified in relation to nuclear matter properties, with predictions of a multifragmentation region in between

  4. 基于流固耦合仿真的小型轴流风扇优化设计%Optimization of Small Axial-flow Fan Based on Fluid-structure Interaction Simulation

    Institute of Scientific and Technical Information of China (English)

    许名珞

    2015-01-01

    为了解决某初步设计的轴流吹风机出风口流量较小的问题,本文对轴流风扇了进行优化设计,最终将风扇叶片翼型由NACA4409翼型改为AH79-100C翼型,叶片安装角由30°增大为32.5°,设计叶片后弯角为8°。基于计算流体力学理论,建立了轴流吹风机流场和轴流风扇风道流场的数值计算模型,运用Fluent软件进行流场数值仿真。基于 ANSYS 软件的Workbench平台,利用流固耦合仿真分析方法对优化后的轴流风扇进行结构分析,校核了新风扇的强度。数值仿真结果表明:仿真结果与企业实验测试结果相符,优化后的轴流吹风机出口流量较优化前增加了10.59%,新风扇轴功率满足企业要求,强度也满足设计要求,总体达到了优化目标。%In order to address the small outlet flowrate issue of a preliminary designed axial flow fan, this paper optimizes the axial-flow fan, changed the airfoil of fan blades from NACA4409 to AH79-100C, increased the blades setting angle from 30 to 32.5 degrees, and designed the blade back-bending angle of 8 degrees. Based on the theory of computational fluid dynamics, a numerical model to compute the air-flow field and the axial-flow fan duct is set up and Fluent software is used to numerically simulate on flow field. Based on the ANSYS Workbench Platform, structural analysis for the optimized axial-flow fan using fluid-structure interaction simulation method is made, and the strength of the new fan is checked. The simulation results show that simulation results coincide with enterprise test results, the outlet flowrate of the optimized axial flow fan increased 10.59%, the shaft power of new axial-flow fan meets enterprise requirements, the strength also meets the design requirements, and the optimization goals are achieved.

  5. FOREWORD: International Summer School for Advanced Studies 'Dynamics of open nuclear systems' (PREDEAL12)

    Science.gov (United States)

    Delion, D. S.; Zamfir, N. V.; Raduta, A. R.; Gulminelli, F.

    2013-02-01

    renowned professors and researchers in nuclear physics. This proceedings volume is organized into four chapters, which reflects the traditional chapter structure of nuclear physics textbooks, but seen from the perspective of open quantum systems: INuclear structure IIDecay processes IIINuclear reactions and astrophysics IVContributions The lectures and contributions are listed alphabetically by author within each chapter. The volume contains many comprehensive reviews related to the topics of the School. The first week of the School was focused on nuclear structure and decay phenomena, considering the nucleus as an open system. Experts in these fields lectured on cluster radioactivity, the stability of superheavy nuclei, alpha-decay fine structure, fission versus fusion, beta and double beta decay and pairing versus alpha-clustering. New experimental results related to the nuclear stability of low-lying and high spin states were also presented. Recent developments at JINR—Dubna and GSI—Darmstadt international laboratories were also reported by their current or former directors. The second week of the event was dedicated to the physics of exotic nuclei, heavy ion reactions and multi-fragmentation, symmetries and phase transitions of open quantum systems. The stability of the atomic nucleus is an important and always interesting discussion point, especially in the context of newly discovered nuclear systems close to the stability line, such as proton/neutron rich or superheavy nuclei. Several lectures and contributions were focused on nuclear structure models describing low-lying states. This includes the status of density functional theory, new developments in Bohr-Mottelsohn Hamiltonian and shell-model theory, proton-neutron correlations, shape coexistence, back-bending phenomena and the thermodynamics of open quantum systems. Open systems in astrophysics, such as supernovae and neutron stars, were presented in detail by several lecturers. Important topics connected to