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Sample records for e1-transitions

  1. Octupole deformation in sup 221 Fr; E1 transition rates

    SciTech Connect

    Liang, C.F.; Peghaire, A. ); Sheline, R.K. )

    1990-07-10

    Experimental data following the alpha decay of{sup 225}Ac are interpreted in terms of a spectroscopy in {sup 221}Fr consistent with octupole deformation. However, the measured E1 transition probabilities suggest that the low lying bands in {sup 221}Fr are considerably more mixed than in nuclei with slightly higher mass number. It is suggested that this mixing of states in {sup 221}Fr is indicative of the partial collapse of Nilsson-like orbitals into more degenerate shell model orbitals.

  2. Enhanced E1 transitions and {alpha}-clustering in {sup 212}Po

    SciTech Connect

    Suzuki, Y.; Ohkubo, S.

    2011-05-06

    An {alpha}+{sup 208}Pb(0{sup +},3{sup -}) cluster model explains the recently observed enhanced E1 transitions from the new negative-parity levels to the yrast states in {sup 212}Po. Heavy and light nuclei present good examples of surface clustering and well-localized clustering.

  3. Enhanced E1 transitions and {alpha}+{sup 208}Pb(3{sup -}) clustering in {sup 212}Po

    SciTech Connect

    Suzuki, Y.; Ohkubo, S.

    2010-10-15

    We formulate a model for {sup 212}Po, based on the coupled-channels of {alpha}+{sup 208}Pb(0{sup +}) and {alpha}+{sup 208}Pb(3{sup -}) in which the {alpha}-Pb interaction contains scalar, quadrupole, and octupole terms. The model reproduces the recently observed enhanced E1 transitions from the several new negative-parity levels to the yrast states. Because these data are hard to understand in the shell model, this success gives a strong support for a unique role of {alpha}+{sup 208}Pb(3{sup -}) clustering in {sup 212}Po.

  4. Calculation of energy levels, {ital E}1 transition amplitudes, and parity violation in francium

    SciTech Connect

    Dzuba, V.A.; Flambaum, V.V.; Sushkov, O.P.

    1995-05-01

    Many-body perturbation theory in the screened Coulomb interaction was used to calculate energy levels, {ital E}1 trransition amplitudes, and the parity-nonconserving (PNC) {ital E}1 amplitude of the 7{ital s}-8{ital s} transition in francium. The method takes into account the core-polarization effect, the second-order correlations, and the three dominating sequences of higher-order correlation diagrams: screening of the electron-electron interaction, particle-hole interaction, and the iterations of the self-energy operator. The result for the PNC amplitude for {sup 223}Fr is {ital E}1(7{ital s}-8{ital s})=(1.59{plus_minus}{similar_to}1%){times}10{sup {minus}10}{ital iea}{sub {ital B}}({minus}{ital Q}{sub {ital W}}/{ital N}), where {ital Q}{sub {ital W}} is the weak charge of the nucleus, {ital N}=136 is the number of neutrons, {ital e}={vert_bar}{ital e}{vert_bar} is the elementary charge, and {ital a}{sub {ital B}} is the Bohr radius. Our prediction for the position of the 8{ital s} energy level of Fr, which has not been measured yet, is 13 110 cm{sup {minus}1} below the limit of the continuous spectrum. The accuracy of the calculations was controlled by comparison with available experimental data and analogous calculations for cesium. It is estimated to be {similar_to}0.1% for the energy levels and {similar_to}1% for the transition amplitudes.

  5. On the enhanced E1 transitions in the K = 3/2 parity doublet band in 223Ra

    NASA Astrophysics Data System (ADS)

    Mach, H.; Lindroth, A.; Ruchowska, E.; Kvasil, J.; Fogelberg, B.; Gulda, K.; Aas, A. J.; Borge, M. J. G.; Grant, I. S.; Hagebø, E.; Kurcewicz, W.; Martinez, T.; Rubio, B.; Smith, J. F.; Steffensen, K.; Tain, J. L.; Tengblad, O.; Thorsteinsen, T. F.

    2016-06-01

    We have applied the fast timing βγγ (t) technique to remeasure lifetimes of selected states in 223Ra populated in the β- decay of 223Fr. T_{1/2}=587(12) ps and 210(13)ps have been obtained for the 3/2- and 5/2- states at 50.1 and 79.7 keV, that are more accurate than the previous values of 630(70)ps and 166(55)ps, respectively. Our \\vert D0\\vert value of 0.155(10)e·fm obtained for the K=3/2 configuration together with the available values of \\vert D0\\vert for the K=1/2 and K=5/2 parity doublet bands establish the configuration dependence of \\vert D0\\vert at low spins in this nucleus. Results of theoretical calculations performed for 223Ra, using the quasiparticle-phonon model (QPM) with inclusion of the Coriolis coupling, reasonably well reproduce octupole correlations in this nucleus.

  6. Fast electric dipole transitions in Ra-Ac nuclei

    SciTech Connect

    Ahmad, I.

    1985-01-01

    Lifetime of levels in /sup 225/Ra, /sup 225/Ac, and /sup 227/Ac have been measured by delayed coincidence techniques and these have been used to determine the E1 gamma-ray transition probabilities. The reduced E1 transition probabilities. The reduced E1 transition probabilities in /sup 225/Ra and /sup 225/Ac are about two orders of magnitude larger than the values in mid-actinide nuclei. On the other hand, the E1 rate in /sup 227/Ac is similar to those measured in heavier actinides. Previous studies suggest the presence of octupole deformation in all the three nuclei. The present investigation indicates that fast E1 transitions occur for nuclei with octupole deformation. However, the studies also show that there is no one-to-one correspondence between E1 rate and octupole deformation. 13 refs., 4 figs.

  7. Octupole correlation effects in nuclei

    SciTech Connect

    Chasman, R.R.

    1992-08-01

    Octupole correlation effects in nuclei are discussed from the point of view of many-body wavefunctions as well as mean-field methods. The light actinides, where octupole effects are largest, are considered in detail. Comparisons of theory and experiment are made for energy splittings of parity doublets; E1 transition matrix elements and one-nucleon transfer reactions.

  8. Octupole correlation effects in nuclei

    SciTech Connect

    Chasman, R.R.

    1992-01-01

    Octupole correlation effects in nuclei are discussed from the point of view of many-body wavefunctions as well as mean-field methods. The light actinides, where octupole effects are largest, are considered in detail. Comparisons of theory and experiment are made for energy splittings of parity doublets; E1 transition matrix elements and one-nucleon transfer reactions.

  9. Are there non-statistical effects in /sup 173/Yb(n,gamma)/sup 174/Yb

    SciTech Connect

    Pospisil, S.; Becvar, F.; Chrien, R.E.; Kopecky, J.

    1987-01-01

    The resonance-averaged capture of neutrons in /sup 173/Yb has been studied at energy of 2 keV. With a statistical significance of 99.5% an enhancement of E1-transition to the neutron 2QP levels in /sup 174/Yb is observed. 8 refs.

  10. Radiative decay of [ital D][sub 2][sup *](2460) and [ital D][sub 1](2420)

    SciTech Connect

    Fayyazuddin; Mobarek, O.H. )

    1994-08-01

    The [ital E]1 transition decay widths for the decays [ital D][sub 2][sup *][r arrow][ital D][sup *]+[gamma], [ital D][sub 1][r arrow][ital D]+[gamma], and [ital D][sub 1][r arrow][ital D][sup *]+[gamma] are calculated in the nonrelativistic quark model with recoil and relativistic corrections.

  11. ACCURATE ESTIMATIONS OF STELLAR AND INTERSTELLAR TRANSITION LINES OF TRIPLY IONIZED GERMANIUM

    SciTech Connect

    Dutta, Narendra Nath; Majumder, Sonjoy E-mail: sonjoy@gmail.com

    2011-08-10

    In this paper, we report on weighted oscillator strengths of E1 transitions and transition probabilities of E2 transitions among different low-lying states of triply ionized germanium using highly correlated relativistic coupled cluster (RCC) method. Due to the abundance of Ge IV in the solar system, planetary nebulae, white dwarf stars, etc., the study of such transitions is important from an astrophysical point of view. The weighted oscillator strengths of E1 transitions are presented in length and velocity gauge forms to check the accuracy of the calculations. We find excellent agreement between calculated and experimental excitation energies. Oscillator strengths of few transitions, wherever studied in the literature via other theoretical and experimental approaches, are compared with our RCC calculations.

  12. Electric dipole transitions between Gamow-Teller and spin-dipole states

    SciTech Connect

    Suzuki, T.; Sagawa, H.; Van Giai, N.

    1998-01-01

    We study electric dipole transitions between Gamow-Teller (GT) and spin-dipole (SD) states. SD and GT excitations are calculated within the Hartree-Fock+Tamm-Dancoff approximation for {sup 48}Sc and {sup 90}Nb. The electric dipole transitions are found to be rather selective, and strong E1 transitions occur to some specific spin-dipole states. Calculated E1 transition strengths between GT and SD states are compared with the analytic sum rules within one-particle{endash}one-hole (1p-1h) configuration space and within both 1p-1h and 2p-2h model space. Possible implications for charge-exchange reactions may help to understand the quenching problem of spin excitations. {copyright} {ital 1998} {ital The American Physical Society}

  13. Phenomenological description of rotational bands in the pear shaped nuclei

    SciTech Connect

    Raduta, A.A.; Raduta, A.H.; Faessler, A.

    1997-04-01

    The coherent state model is extended to negative parity states. Thus three positive (ground, beta, and gamma) and three negative parity bands are projected out from three orthogonal states exhibiting both quadrupole and octupole deformations. An effective Hamiltonian acting on the space of projected states is constructed. For illustration, the numerical application is confined to the ground and K{sup {pi}}=0{sup {minus}} bands. In a certain range of deformations these bands show a {open_quotes}shell{close_quotes} structure. Good agreement with experimental data in {sup 218,220,226}Ra is obtained for energy levels and E1 transition probabilities. Specific features like the interleaved structure, the low energy of the state 1{sup {minus}}, and strong E1 transitions are well described. {copyright} {ital 1997} {ital The American Physical Society}

  14. Alternating parity structure in doubly odd /sup 218/Ac

    SciTech Connect

    Debray, M.E.; Davidson, M.; Kreiner, A.J.; Davidson, J.; Falcone, G.; Hojman, D.; Santos, D.

    1989-03-01

    States in doubly odd /sup 218/Ac have been studied using in-beam ..cap alpha..-, ..gamma..-, and e/sup -/-spectroscopy techniques mainly through the /sup 209/Bi(/sup 12/C,3n)= fusion-evaporation reaction. /sup 218/Ac shows a band structure, with interleaved states of alternating parities connected by enhanced B(E1) transitions, which is strikingly similar to the one in its isotone /sup 217/Ra.

  15. Comparative studies in direct slow-neutron capture calculations

    SciTech Connect

    Mughabghab, S.F.

    1987-08-01

    Primary E1 transitions due to thermal neutron capture by the nuclides /sup 9/Be, /sup 32,34/S, /sup 40,42,44,46,48/Ca, and /sup 58/Ni are quantitatively interpreted by the Lane-Lynn formula and are compared with recent optical model calculations. The two approaches are equivalent provided the internal region of the nucleus is excluded in the optical model approach. Theoretical justifications for such a procedure are briefly presented. 32 refs., 4 tabs.

  16. Recent results at the N = Z line with GASP and EUROBALL

    SciTech Connect

    Farnea, E.

    2004-02-27

    Valuable information on the validity of the isospin symmetry was obtained by studying nuclei close to the N = Z line with the GASP and EUROBALL {gamma}-ray spectrometres coupled to ancillary devices. Here a few selected results on the study of mirror nuclei are presented, together with an estimate of the isospin mixing probability through the measurement of a forbidden E1 transition in 64Ge.

  17. Reflection Asymmetric Shapes in the Neutron-Rich 140,143Ba Isotopes

    NASA Astrophysics Data System (ADS)

    Zhu Sheng-jiang (S, J. Zhu; Wang, Mu-ge; J, H. Hamilton; A, V. Ramayya; B, R. S. Babu; W, C. Ma; Long, Gui-lu; Deng, Jing-kang; Zhu, Ling-yan; Li, Ming; T, N. Ginter; J, Komicki; J, D. Cole; R, Aryaeinejad; Y, K. Dardenne; M, W. Drigert; J, O. Rasmussen; Ts, Yu Oganessian; M, A. Stoyer; S, Y. Chu; K, E. Gregorich; M, F. Mohar; S, G. Prussin; I, Y. Lee; N, R. Johnson; F, K. McGowan

    1997-08-01

    Level schemes for the neutron-rich 140,143Ba nuclei have been determined by study of prompt γ-rays in spontaneous fission of 252Cf. The level pattern and enhanced E1 transitions between π = + and π = - bands show reflection asymmetric shapes with simplex quantum number s = +1 in 140Ba and s = ±i in 143Ba, respectively. The octupole deformation stability with spin variation has been discussed.

  18. Relativistic Many-body Moller-Plesset Perturbation Theory Calculations of the Energy Levels and Transition Probabilities in Na- to P-like Xe Ions

    SciTech Connect

    Vilkas, M J; Ishikawa, Y; Trabert, E

    2007-03-27

    Relativistic multireference many-body perturbation theory calculations have been performed on Xe{sup 43+}-Xe{sup 39+} ions, resulting in energy levels, electric dipole transition probabilities, and level lifetimes. The second-order many-body perturbation theory calculation of energy levels included mass shifts, frequency-dependent Breit correction and Lamb shifts. The calculated transition energies and E1 transition rates are used to present synthetic spectra in the extreme ultraviolet range for some of the Xe ions.

  19. Quasiparticle structure of superheavy nuclei along the α -decay chain of 288115

    NASA Astrophysics Data System (ADS)

    Bezbakh, A. N.; Kartavenko, V. G.; Adamian, G. G.; Antonenko, N. V.; Jolos, R. V.; Nesterenko, V. O.

    2015-07-01

    Background: Recent experiments on α -decay of odd-odd superheavy nuclei give important information on the structure of the low-lying states of these nuclei. For this reason, it is interesting to calculate the excitation spectra of superheavy nuclei in the framework of different approaches and compare the results with the experimental data. Purpose: To calculate the excitation energies of the two-quasiparticle states of nuclei belonging to the α -decay chain of 288115 nucleus. Method: Two different single-particle potentials, modified two-center and Skyrme-based potentials, are used to calculate the energies of two-quasiparticle states. Results: The spectra of the low-lying states are calculated. An evolution of the splitting of the pseudospin doublets and an evolution of the energies of the unique parity single-particle states with the nuclear mass number are investigated. The α -decay spectra of nuclei belonging to the α -decay chain of 288115 are obtained and compared with the experimental data. A possibility of the E 1 transitions in 276Mt following α decay of 288115 is considered. Conclusion: The E 1 transitions in 276Mt might be related to the transitions n 9 /2 [604 ]→n 11 /2 [725 ] ,n 11 /2 [725 ]→n 9 /2 [615 ] , and p 9 /2 [505 ]→p 11 /2 [615 ] . Besides the E 1 transitions, the strong M 1 and M 2 transitions are expected in 276Mt.

  20. Measurement method for the nuclear anapole moment of laser-trapped alkali-metal atoms

    SciTech Connect

    Gomez, E.; Aubin, S.; Sprouse, G. D.; Orozco, L. A.; DeMille, D. P.

    2007-03-15

    Weak interactions within a nucleus generate a nuclear spin dependent, parity-violating electromagnetic moment, the anapole moment. We analyze a method to measure the nuclear anapole moment through the electric dipole transition it induces between hyperfine states of the ground level. The method requires tight confinement of the atoms to position them at the antinode of a standing wave Fabry-Perot cavity driving the anapole-induced microwave E1 transition. We explore the necessary limits in the number of atoms, excitation fields, trap type, interrogation method, and systematic tests necessary for such measurements in francium, the heaviest alkali.

  1. Evidence for the onset of reflection asymmetry in sup 216 Fr

    SciTech Connect

    Debray, M.E.; Davidson, J.; Davidson, M.; Kreiner, A.J.; Hojman, D.; Santos, D. ); Ahn, K.; Fossan, D.B.; Liang, Y.; Ma, R.; Paul, E.S.; Piel, W.F. Jr.; Xu, N. )

    1990-05-01

    States in doubly odd {sup 216}Fr have been studied using in-beam {alpha}, {gamma}, and {ital e}{sup {minus}} spectroscopy techniques through the {sup 208}Pb({sup 11}B3{ital n}) fusion-evaporation reaction. {sup 216}Fr shows a band structure with interleaved states of alternating parities connected by enhanced {ital B}({ital E}1) transitions. It represents the lowest-mass corner of the region ({ital Z}{ge}87,{ital N}{ge}129) in which this phenomenon is observed.

  2. Energies and Electric Dipole Transitions for Low-Lying Levels of Protactinium IV and Uranium V

    NASA Astrophysics Data System (ADS)

    Ürer, Güldem; Özdemir, Leyla

    2012-02-01

    We have reported a relativistic multiconfiguration Dirac-Fock (MCDF) study on low-lying level structures of protactinium IV (Z =91) and uranium V (Z =92) ions. Excitation energies and electric dipole (E1) transition parameters (wavelengths, oscillator strengths, and transition rates) for these low-lying levels have been given. We have also investigated the influence of the transverse Breit and quantum electrodynamic (QED) contributions besides correlation effects on the level structure. A comparison has been made with a few available data for these ions in the literature.

  3. New results on the superdeformed {sup 196}Pb nucleus: The decay of the excited bands to the yrast band

    SciTech Connect

    Bouneau, S.; Azaiez, F.; Duprat, J.

    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.

  4. A Large-scale Relativistic Configuration-interaction Approach: Application to the 4s2 - 4s4p Transition Energies and E1 Rates for Zn-like Ions

    SciTech Connect

    Chen, M H; Cheng, K T

    2009-08-28

    Relativistic configuration-interaction calculations of the 4s4p excitation energies and 4s{sup 2} - 4s4p E1 transitions for Zn-like ions from Z = 30 to 92 are shown. B-spline basis functions are used for these large-scale calculations. QED corrections to the excitation energies are also calculated. Results are in good agreement with other theories and with experiment, and demonstrate the utility of this method for high-precision atomic structure calculations not just for few-electron systems but also for large atomic systems such as Zn-like ions along the entire isoelectronic sequence.

  5. Inter-band coincidences in the superdeformed well of {sup 190}Hg from gammasphere

    SciTech Connect

    Crowell, B.; Carpenter, M.P.; Janssens, R.V.F.

    1995-08-01

    Very few experimental observables are ordinarily accessible for superdeformed (SD) states in the A {approximately} 150 and A {approximately} 190 regions. The gamma-decay out of the superdeformed bands usually proceeds directly to the normally deformed states, through highly fragmented pathways, making it difficult to determine the spins, parities and excitation energies of the SD states. The in-band E2 transitions are so collective (2 x 10{sup 3} single-particle units in the A {approximately} 190 region) that it is typically impossible to detect any of the competing M1 and E1 transitions between states in the SD well.

  6. Radiative p 15N Capture in the Region of Astrophysical Energies

    NASA Astrophysics Data System (ADS)

    Dubovichenko, S. B.; Burtebaev, N.; Dzhazairov-Kakhramanov, A. V.; Alimov, D. K.

    2016-06-01

    Within the framework of the modified potential cluster model with classification of orbital states according to the Young schemes, the possibility of describing experimental data for the astrophysical S-factor of p 15N radiative capture at energies from 50 to 1500 keV is considered. It is shown that on the basis of M1 and E1 transitions from various p 15N scattering states to the ground state of the 16O nucleus in the p 15N channel it is entirely possible to successfully explain the overall behavior of the S-factor in the considered energy region in the presence of two resonances.

  7. Electron-Hole Transitions in Multiply Charged Ions for Precision Laser Spectroscopy and Searching for Variations in {alpha}

    SciTech Connect

    Berengut, J. C.; Dzuba, V. A.; Flambaum, V. V.; Ong, A.

    2011-05-27

    We consider transitions of electron holes (vacancies in otherwise filled shells of atomic systems) in multiply charged ions that, due to level crossing of the holes, have frequencies within the range of optical atomic clocks. Strong E1 transitions provide options for laser cooling and trapping, while narrow transitions can be used for high-precision spectroscopy and tests of fundamental physics. We show that hole transitions can have extremely high sensitivity to {alpha} variation and propose candidate transitions that have much larger {alpha} sensitivities than any previously seen in atomic systems.

  8. Octupole shapes in heavy nuclei

    SciTech Connect

    Ahmad, I.

    1994-08-01

    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.

  9. Evidence for reflection asymmetric shape in the nucleus sup 151 sub 61 Pm sub 90

    SciTech Connect

    Sood, P.C.; Sheline, R.K. )

    1989-09-01

    The occurrence of multiple parity doublets, enhanced {ital E}1 transitions between parity-doublet levels, characteristic decoupling parameters for {ital K}=1/2 parity-doublet bands, and hybridization of the nuclear magnetic moments are sought as evidence for reflection asymmetric shape in odd-{ital Z} odd-mass rare-earth nuclei. Specific results consistent with such an assumption are presented for the nucleus {sup 151}{sub 61}Pm{sub 90}. Suggestions are offered for further experiments following a review of available information on other nuclei of the region.

  10. Octupole Deformation Bands of πh11/2 in Neutron-Rich 145,147La Nuclei

    NASA Astrophysics Data System (ADS)

    Zhu, Sheng-jiang; S, Zhu J.; Wang, Mu-ge; J, Hamilton H.; A, Ramayya V.; B, Babu R. S.; W, Ma C.; Long, Gui-lu; Zhu, Ling-yan; Li, Ming; A, Sakhaee; Gan, Cui-yun; Yang, Li-ming; J, Komicki; J, Cole D.; R, Aryaeinejad; M, Drigert W.; J, Rasmussen O.; M, Stoyer A.; S, Chu Y.; K, Gregorich E.; M, Mohar F.; S, Prussin G.; I, Lee Y.; Yu, Oganessian Ts; G, Ter-Akopian M.; A, Daniel V.

    1999-03-01

    Octupole deformation bands built on πh11/2 orbital in neutron-rich odd-Z 145,147La nuclei have been investigated by measuring the prompt γ-rays emitted from the 252Cf source. The alternating parity band structures and strong E1 transitions observed between negative- and positive-parity bands in both nuclei indicate the octupole deformation enhanced by the h11/2 single proton coupling. According to observed energy displacements the octupole deformation becomes stable at the intermediate spin states.

  11. Limitations of the semirelativistic approach in sum rules and related calculations in atomic physics

    NASA Technical Reports Server (NTRS)

    Rustgi, M. L.; Leung, P. T.; Long, S. A. T.

    1988-01-01

    The semirelativistic approach, as applied to sum-rule calculations, can yield very inaccurate results for high-Z systems; the apparently good agreement previously reported is fortuitous, due to the application of an approximate eigenstate of the semirelativistic Hamiltonian. Attention is given to one-electron atomic systems, and the results obtained are discussed with a view to their implications for many-electron systems. The many-electron problem is complicated by a lack of clarity as to the relative importance of contributions due to correlation effects among the electrons, their effect on the E2 oscillator strength, and the retardation correction to the E1 transition.

  12. Theoretical study of the α +d →6Li +γ astrophysical capture process in a three-body model

    NASA Astrophysics Data System (ADS)

    Tursunov, E. M.; Kadyrov, A. S.; Turakulov, S. A.; Bray, I.

    2016-07-01

    The astrophysical capture process α +d →6Li is studied in a three-body model. The initial state is factorized into the deuteron bound state and the (α +d )-scattering state. The final nucleus 6Li (1+) is described as a three-body bound state α +n +p in the hyperspherical Lagrange-mesh method. The contribution of the E 1 -transition operator from the initial isosinglet states to the isotriplet components of the final state is estimated to be negligible. An estimation of the forbidden E 1 transition to the isosinglet components of the final state is comparable with the corresponding results of the two-body model. However, the contribution of the E 2 -transition operator is found to be much smaller than the corresponding estimations of the two-body model. The three-body model perfectly matches the new experimental data of the LUNA Collaboration with the spectroscopic factor of 2.586 estimated from the bound-state wave functions of 6Li and a deuteron.

  13. Astrophysical S factors for radiative proton capture by {sup 3}H and {sup 7}Li nuclei

    SciTech Connect

    Dubovichenko, S. B.

    2011-03-15

    Within the potential cluster model where orbital states are classified according to Young diagrams and isospin, astrophysical S factors are considered for radiative proton capture by {sup 3}H and {sup 7}Li nuclei at energies of up to 1 and 10 keV, respectively. It is shown that the approach used, which takes into account only the E1 transition for the p{sup 3}H capture process, makes it possible to describe well the most recent experimental data at c.m. energies in the range from 50 keV to 5MeV. In the case of proton capture by {sup 7}Li nuclei, an M1 processwas taken into account in addition to the E1 transition, and a general behavior and the magnitude of the experimental S factor could be correctly reproduced owing to this at astrophysical energies, including the region around the resonance at 0.441 MeV (in the laboratory frame).

  14. Direct Neutron Capture Calculations with Covariant Density Functional Theory Inputs

    NASA Astrophysics Data System (ADS)

    Zhang, Shi-Sheng; Peng, Jin-Peng; Smith, Michael S.; Arbanas, Goran; Kozub, Ray L.

    2014-09-01

    Predictions of direct neutron capture are of vital importance for simulations of nucleosynthesis in supernovae, merging neutron stars, and other astrophysical environments. We calculate the direct capture cross sections for E1 transitions using nuclear structure information from a covariant density functional theory as input for the FRESCO coupled-channels reaction code. We find good agreement of our predictions with experimental cross section data on the double closed-shell targets 16O, 48Ca, and 90Zr, and the exotic nucleus 36S. Extensions of the technique for unstable nuclei and for large-scale calculations will be discussed. Predictions of direct neutron capture are of vital importance for simulations of nucleosynthesis in supernovae, merging neutron stars, and other astrophysical environments. We calculate the direct capture cross sections for E1 transitions using nuclear structure information from a covariant density functional theory as input for the FRESCO coupled-channels reaction code. We find good agreement of our predictions with experimental cross section data on the double closed-shell targets 16O, 48Ca, and 90Zr, and the exotic nucleus 36S. Extensions of the technique for unstable nuclei and for large-scale calculations will be discussed. Supported by the U.S. Dept. of Energy, Office of Nuclear Physics.

  15. Discovery of a 10 {mu}s isomeric state in {sub 63}{sup 139}Eu

    SciTech Connect

    Cullen, D. M.; Mason, P. J. R; Kishada, A. M.; Procter, M. G.; Rigby, S. V.; Varley, B. J.; Scholey, C.; Eeckhaudt, S.; Grahn, T.; Greenlees, P. T.; Jakobsson, U.; Jones, P. M.; Julin, R.; Juutinen, S.; Ketelhut, S.; Leino, M.; Leppaenen, A.-P.; Maentyniemi, K.; Nieminen, P.; Nyman, M.

    2011-01-15

    Recoil-isomer tagging with the {sup 54}Fe+{sup 92}Mo reaction was used to establish a 10(2)-{mu}s isomeric state in {sup 139}Eu. Prompt versus delayed {gamma}-ray coincidence data have revealed the presence of a prompt rotational band built upon the isomer. The alignment properties of the states in this band show that the isomer is based upon a proton g{sub 7/2} configuration. The decay of the isomer takes place through a single 26-keV E1 transition. The {gamma}-ray transition strength for this decay is consistent with those established in the neighboring isomeric gamma-soft nuclei. In these nuclei, isomers are expected to form as a consequence of differences in nuclear shapes or configurations, and the natural hindrance associated with configuration-changing E1 transitions. The isomeric nature of the state in {sup 139}Eu is reasoned to be because of difference in shape of the proton g{sub 7/2} state and the proton h{sub 11/2} ground state to which it decays.

  16. Current status of the measurement of the anapole moment

    NASA Astrophysics Data System (ADS)

    Sheng, Dong; Perez Galvan, Adrian; Hood, Jonathan; Orozco, Luis

    2009-05-01

    We present the current status of the experimental effort towards the measurement of the anapole moment in different isotopes of francium. The anapole is a parity-violating, time-reversal conserving nuclear moment that arises from the weak interaction among nucleons. Due to the electromagnetic interaction between electrons and nucleons, atomic physics gives the unique possibility to probe the weak interaction in the low energy regime. Our experimental scheme involves driving a parity forbidden E1 transition between hyperfine ground states in a series of francium isotopes inside a blue detuned dipole trap at the electric antinode of a microwave cavity. The experiment will make use of the ISAC radioactive beam facility at TRIUMF. The system is currently being tested with rubidium.

  17. Progress on the measurement of the francium anapole moment

    NASA Astrophysics Data System (ADS)

    Sheng, Dong; Hood, Jonathan; Lynam, Steven; Orozco, Luis; Gomez, Eduardo; Aubin, Seth; Gwinner, Gerald; Behr, John; Pearson, Matthew; Jackson, Peter; Melconian, Dan; Flambaum, Victor; Sprouse, Gene

    2010-03-01

    We present the current status of the experimental effort towards the measurement of the anapole moment in francium. The anapole is a parity violating, time-reversal conserving nuclear moment that arises from the weak interaction among nucleons. The anapole moment is nuclear spin dependent (nsd) and sensitive to the configuration of nuclear structure. Our experimental scheme is to perform a direct measurement of the nsd parity violation, by driving a parity forbidden E1 transition between hyperfine ground states in a series of francium isotopes inside a blue detuned dipole trap at the electric anti-node of a microwave cavity. We explore theoretical aspects and experimental requirements on the possible tests using rubidium isotopes. The experiment will be at the ISAC radioactive beam facility of TRIUMF. Work supported by NSF and DOE USA, NSERC and NRC Canada, CONACYT Mexico.

  18. Electromagnetic selection rules in the triangular α-cluster model of 12C

    NASA Astrophysics Data System (ADS)

    Stellin, G.; Fortunato, L.; Vitturi, A.

    2016-08-01

    After recapitulating the procedure to find the bands and the states occurring in the {{ D }}3h alpha-cluster model of 12C in which the clusters are placed at the vertexes of an equilateral triangle, we obtain the selection rules for electromagnetic transitions. While the alpha-cluster structure leads to the cancellation of E1 transitions, the approximations carried out in deriving the rotational-vibrational Hamiltonian lead to the disappearance of M1 transitions. Furthermore, although in general the lowest active modes are E2, E3, ... and M2, M3, ..., the cancellation of M2, M3 and M5 transitions between certain bands also occur as a result of the application of group theoretical techniques drawn from molecular physics. These implications can be very relevant for the spectroscopic analysis of γ-ray spectra of 12C.

  19. Multipole character of the proposed 220 eV transition in [sup 229]Pa

    SciTech Connect

    Dragoun, O.; Rysavy, M. ); Guenther, C. )

    1993-02-01

    Internal conversion coefficients (ICC's) have been calculated for protactinium and transition energies between 170 eV and 10 keV. The ICC's for [ital E]1 multipolarity show an unusual behavior, which cannot be approximated by an exponential dependence on the transition energy, whereas the ICC's for [ital M]1 and [ital E]2 multipolarities closely follow such a dependence. Using the newly calculated ICC's the unusually strong enhancement'' of a possible 220 eV [ital E]1 transition in [sup 229]Pa proposed earlier is reduced by a factor of [similar to]5, yielding an induced electric dipole moment similar to that observed in the neighboring octupole-deformed isotopes.

  20. Proposed s =±1 octupole bands in 140Xe

    NASA Astrophysics Data System (ADS)

    Huang, Y.; Zhu, S. J.; Hamilton, J. H.; Wang, E. H.; Ramayya, A. V.; Xiao, Z. G.; Li, H. J.; Luo, Y. X.; Rasmussen, J. O.; Ter-Akopian, G. M.; Oganessian, Yu. Ts.

    2016-06-01

    Level structures of neutron-rich 140Xe nucleus have been reinvestigated by using a triple γ coincidence study from the spontaneous fission of 252Cf. Several new levels and transitions are identified. The previously observed s =+1 octupole band structure is confirmed and expanded. Another set of the Δ I =2 positive and negative parity bands connected by strong E 1 transitions is proposed as the s =-1 octupole band structure. Thus, the s =±1 doublet octupole bands are completed in 140Xe. The experimental B (E 1 )/B (E 2 ) branching ratios indicate that the octupole correlations in 140Xe are weak. The other characteristics of the s =±1 octupole bands have been discussed.

  1. Radiative n 14N capture at astrophysical energies

    NASA Astrophysics Data System (ADS)

    Dubovichenko, S. B.

    2013-06-01

    In the potential cluster model with forbidden states and classification of orbital cluster states according to Young's schemes, the possibility is considered of describing the experimental data for the total cross sections of radiative n 14N capture at energies from 25.0 meV (25•10-3 eV) to 1.0 MeV. It is shown that on the whole it is possible to successfully explain the behavior of these cross sections outside the resonant energy region on the basis of the E1 transition from the 2S1/2 scattering wave with zero phase to the bound 2Р1/2 state of the 15N nucleus in the n14N channel.

  2. Observation of χcJ decays to ΛΛ¯¯¯π⁺π⁻

    SciTech Connect

    Ablikim, M.; Achasov, M. N.; Ambrose, D. J.; An, F. F.; An, Q.; An, Z. H.; Bai, J. Z.; Ban, Y.; Becker, J.; Bennett, J. V.; Bertani, M.; Bian, J. M.; Boger, E.; Bondarenko, O.; Boyko, I.; Briere, R. A.; Bytev, V.; Cai, X.; Cakir, O.; Calcaterra, A.; Cao, G. F.; Cetin, S. A.; Chang, J. F.; Chelkov, G.; Chen, G.; Chen, H. S.; Chen, J. C.; Chen, M. L.; Chen, S. J.; Chen, Y. B.; Cheng, H. P.; Chu, Y. P.; Cronin-Hennessy, D.; Dai, H. L.; Dai, J. P.; Dedovich, D.; Deng, Z. Y.; Denig, A.; Denysenko, I.; Destefanis, M.; Ding, W. M.; Ding, Y.; Dong, L. Y.; Dong, M. Y.; Du, S. X.; Fang, J.; Fang, S. S.; Fava, L.; Feldbauer, F.; Feng, C. Q.; Ferroli, R. B.; Fu, C. D.; Fu, J. L.; Gao, Y.; Geng, C.; Goetzen, K.; Gong, W. X.; Gradl, W.; Greco, M.; Gu, M. H.; Gu, Y. T.; Guan, Y. H.; Guo, A. Q.; Guo, L. B.; Guo, Y. P.; Han, Y. L.; Harris, F. A.; He, K. L.; He, M.; He, Z. Y.; Held, T.; Heng, Y. K.; Hou, Z. L.; Hu, H. M.; Hu, J. F.; Hu, T.; Huang, G. M.; Huang, J. S.; Huang, X. T.; Huang, Y. P.; Hussain, T.; Ji, C. S.; Ji, Q.; Ji, X. B.; Ji, X. L.; Jiang, L. L.; Jiang, X. S.; Jiao, J. B.; Jiao, Z.; Jin, D. P.; Jin, S.; Jing, F. F.; Kalantar-Nayestanaki, N.; Kavatsyuk, M.; Kuehn, W.; Lai, W.; Lange, J. S.; Li, C. H.; Li, Cheng; Li, Cui; Li, D. M.; Li, F.; Li, G.; Li, H. B.; Li, J. C.; Li, K.; Li, Lei; Li, Q. J.; Li, S. L.; Li, W. D.; Li, W. G.; Li, X. L.; Li, X. N.; Li, X. Q.; Li, X. R.; Li, Z. B.; Liang, H.; Liang, Y. F.; Liang, Y. T.; Liao, G. R.; Liao, X. T.; Liu, B. J.; Liu, C. L.; Liu, C. X.; Liu, C. Y.; Liu, F. H.; Liu, Fang; Liu, Feng; Liu, H.; Liu, H. B.; Liu, H. H.; Liu, H. M.; Liu, H. W.; Liu, J. P.; Liu, K. Y.; Liu, Kai; Liu, P. L.; Liu, Q.; Liu, S. B.; Liu, X.; Liu, X. H.; Liu, Y. B.; Liu, Z. A.; Liu, Zhiqiang; Liu, Zhiqing; Loehner, H.; Lu, G. R.; Lu, H. J.; Lu, J. G.; Lu, Q. W.; Lu, X. R.; Lu, Y. P.; Luo, C. L.; Luo, M. X.; Luo, T.; Luo, X. L.; Lv, M.; Ma, C. L.; Ma, F. C.; Ma, H. L.; Ma, Q. M.; Ma, S.; Ma, T.; Ma, X. Y.; Ma, Y.; Maas, F. E.; Maggiora, M.; Malik, Q. A.; Mao, Y. J.; Mao, Z. P.; Messchendorp, J. G.; Min, J.; Min, T. J.; Mitchell, R. E.; Mo, X. H.; Morales Morales, C.; Motzko, C.; Muchnoi, N. Yu.; Muramatsu, H.; Nefedov, Y.; Nicholson, C.; Nikolaev, I. B.; Ning, Z.; Olsen, S. L.; Ouyang, Q.; Pacetti, S.; Park, J. W.; Pelizaeus, M.; Peng, H. P.; Peters, K.; Ping, J. L.; Ping, R. G.; Poling, R.; Prencipe, E.; Qi, M.; Qian, S.; Qiao, C. F.; Qin, X. S.; Qin, Y.; Qin, Z. H.; Qiu, J. F.; Rashid, K. H.; Rong, G.; Ruan, X. D.; Sarantsev, A.; Schaefer, B. D.; Schulze, J.; Shao, M.; Shen, C. P.; Shen, X. Y.; Sheng, H. Y.; Shepherd, M. R.; Song, X. Y.; Spataro, S.; Spruck, B.; Sun, D. H.; Sun, G. X.; Sun, J. F.; Sun, S. S.; Sun, Y. J.; Sun, Y. Z.; Sun, Z. J.; Sun, Z. T.; Tang, C. J.; Tang, X.; Tapan, I.; Thorndike, E. H.; Toth, D.; Ullrich, M.; Varner, G. S.; Wang, B.; Wang, B. Q.; Wang, K.; Wang, L. L.; Wang, L. S.; Wang, M.; Wang, P.; Wang, P. L.; Wang, Q.; Wang, Q. J.; Wang, S. G.; Wang, X. L.; Wang, Y. D.; Wang, Y. F.; Wang, Y. Q.; Wang, Z.; Wang, Z. G.; Wang, Z. Y.; Wei, D. H.; Weidenkaff, P.; Wen, Q. G.; Wen, S. P.; Werner, M.; Wiedner, U.; Wu, L. H.; Wu, N.; Wu, S. X.; Wu, W.; Wu, Z.; Xia, L. G.; Xiao, Z. J.; Xie, Y. G.; Xiu, Q. L.; Xu, G. F.; Xu, G. M.; Xu, H.; Xu, Q. J.; Xu, X. P.; Xu, Z. R.; Xue, F.; Xue, Z.; Yan, L.; Yan, W. B.; Yan, Y. H.; Yang, H. X.; Yang, Y.; Yang, Y. X.; Ye, H.; Ye, M.; Ye, M. H.; Yu, B. X.; Yu, C. X.; Yu, J. S.; Yu, S. P.; Yuan, C. Z.; Yuan, Y.; Zafar, A. A.; Zallo, A.; Zeng, Y.; Zhang, B. X.; Zhang, B. Y.; Zhang, C. C.; Zhang, D. H.; Zhang, H. H.; Zhang, H. Y.; Zhang, J. Q.; Zhang, J. W.; Zhang, J. Y.; Zhang, J. Z.; Zhang, S. H.; Zhang, X. J.; Zhang, X. Y.; Zhang, Y.; Zhang, Y. H.; Zhang, Y. S.; Zhang, Z. P.; Zhang, Z. Y.; Zhao, G.; Zhao, H. S.; Zhao, J. W.; Zhao, K. X.; Zhao, Lei; Zhao, Ling; Zhao, M. G.; Zhao, Q.; Zhao, S. J.; Zhao, T. C.; Zhao, X. H.; Zhao, Y. B.; Zhao, Z. G.; Zhemchugov, A.; Zheng, B.; Zheng, J. P.; Zheng, Y. H.; Zhong, B.; Zhong, J.; Zhou, L.; Zhou, X. K.; Zhou, X. R.; Zhu, C.; Zhu, K.; Zhu, K. J.; Zhu, S. H.; Zhu, X. L.; Zhu, X. W.; Zhu, Y. C.; Zhu, Y. M.; Zhu, Y. S.; Zhu, Z. A.; Zhuang, J.; Zou, B. S.; Zou, J. H.

    2012-09-13

    Decays of the χcJ states (J=0, 1, 2) to ΛΛ¯¯¯π⁺π⁻, including processes with intermediate Σ(1385), are studied through the E1 transition ψ'→γχcJ using 106×10⁶ ψ' events collected with the BESIII detector at BEPCII. This is the first observation of χcJ decays to the final state ΛΛ¯¯¯π⁺π⁻. The branching ratio of the intermediate process χcJ→Σ(1385)±Σ¯¯¯(1385) is also measured for the first time, and the results agree with the theoretical predictions based on the color-octet effect.

  3. Observation of χcJ decays to ΛΛ¯¯¯π⁺π⁻

    DOE PAGESBeta

    Ablikim, M.; Achasov, M. N.; Ambrose, D. J.; An, F. F.; An, Q.; An, Z. H.; Bai, J. Z.; Ban, Y.; Becker, J.; Bennett, J. V.; et al

    2012-09-13

    Decays of the χcJ states (J=0, 1, 2) to ΛΛ¯¯¯π⁺π⁻, including processes with intermediate Σ(1385), are studied through the E1 transition ψ'→γχcJ using 106×10⁶ ψ' events collected with the BESIII detector at BEPCII. This is the first observation of χcJ decays to the final state ΛΛ¯¯¯π⁺π⁻. The branching ratio of the intermediate process χcJ→Σ(1385)±Σ¯¯¯(1385)∓ is also measured for the first time, and the results agree with the theoretical predictions based on the color-octet effect.

  4. Odd tensor electric transitions in high-spin Sn-isomers and generalized seniority

    NASA Astrophysics Data System (ADS)

    Maheshwari, Bhoomika; Jain, Ashok Kumar

    2016-02-01

    The similar behavior of the B (E 1) values of the recently observed 13- odd tensor E1 isomers and the B (E 2) values of the 10+ and 15- even tensor E2 isomers in the Sn-isotopes has been understood in terms of the generalized seniority for multi-j orbits by using the quasi-spin scheme. This simple approach proves to be quite successful in explaining the measured transition probabilities and the corresponding half-lives in the high-spin isomers of the semi-magic Sn-isotopes. Hence, we show for the first time the occurrence of seniority isomers in the 13- Sn-isomers, which decay by odd-tensor E1 transitions to the same seniority states.

  5. Astrophysical S-factor for the radiative-capture reaction p{sup 13}C {yields} {sup 14}N{gamma}

    SciTech Connect

    Dubovichenko, S. B.

    2012-02-15

    The possibility of describing experimental data on the astrophysical S factor for radiative proton capture on a {sup 13}C nucleus at energies in the range 0.03-0.8 MeV is considered within the potential cluster model involving forbidden states. It is shown that the energy dependence of this astrophysical S factor can be reasonably explained on the basis of the E1 transition to the {sup 3}P{sub 1}-wave bound state of the {sup 14}N nucleus in the p{sup 13}C channel from the {sup 3}S{sub 1} wave of p{sup 13}C scattering in the resonance energy region around 0.55 MeV in the laboratory frame.

  6. Isospin Symmetry Along The N=Z Line In The sd Shell

    SciTech Connect

    Della Vedova, F.; Lenzi, S. M.; Farnea, E.; Nespolo, M.; Bazzacco, D.; Brandolini, F.; Lunardi, S.; Menegazzo, R.; Rossi Alvarez, C.; Ur, C.A.; Ionescu-Bujor, M.; Bucurescu, D.; Iordachescu, A.; Marginean, N.; De Angelis, G.; Axiotis, M.; Napoli, D. R.; Bizzeti-Sona, A.; Bizzeti, P.G.

    2005-04-05

    Excited states have been studied in sd-shell nuclei following the 16O (70 MeV) + 24Mg (400 {mu}g/cm2) fusion-evaporation reaction. The GASP spectrometer in conjunction with the charged-particle detector ISIS and the Neutron ring allowed the detection of the {gamma}-rays in coincidence with evaporated light particles. New data on the mirror pairs A=31 and A=35 have been obtained. In particular, the comparison between the level schemes of 35Ar and 35Cl has confirmed the importance of the electromagnetic spin-orbit term, which explains the large Mirror Energy Difference values. Evidence of isospin mixing can be deduced from the E1 transitions.

  7. Formation of two-dimensional nonspreading atomic wave packets in the field of two standing light waves

    SciTech Connect

    Efremov, M A; Fedorov, Mikhail V; Petropavlovsky, S V; Yakovlev, V P; Schleich, Wolfgang P

    2005-08-31

    The formation of two-dimensional nonspreading atomic wave packets produced in the interaction of a beam of two-level atoms with two standing light waves polarised in the same plane is considered. The mechanism providing a dispersionless particle dynamics is the balance of two processes: a rapid decay of the atomic wave function away from the field nodes due to spontaneous transitions to nonresonance states and the quantum broadening of the wave packets formed in the close vicinity of field nodes. Coordinate-dependent amplitudes and phases of the two-dimensional wave packets were found for the j{sub g}=0 {r_reversible} j{sub e}=1 transition. (fourth seminar to the memory of d.n. klyshko)

  8. Experimental efforts at NIST towards one-electron ions in circular Rydberg states

    NASA Astrophysics Data System (ADS)

    Tan, Joseph N.; Brewer, Samuel M.; Guise, Nicholas D.

    2011-06-01

    Experimental effort is underway at NIST to enable tests of theory with one-electron ions synthesized in circular Rydberg states from captured bare nuclei. Problematic effects that limit the accuracy of predicted energy levels for low-lying states are vanishingly small for high-angular-momentum (high-L) states; in particular, the nuclear size correction for high-L states is completely negligible for any foreseeable improvement of measurement precision. As an initial step towards realizing such states, highly charged ions are extracted from the NIST electron beam ion trap (EBIT) and steered through the electrodes of a Penning trap. The goal is to capture bare nuclei in the Penning trap for experiments to make one-electron atoms in circular Rydberg states with dipole (E1) transitions in the optical domain accessible to a frequency comb.

  9. High Spin States and Octupole Deformation in Neutron-Rich ^145,147La Nuclei

    NASA Astrophysics Data System (ADS)

    Zhu, S. J.; Hamilton, J. H.; Ramayya, A. V.; Babu, B. R. S.; Jones, E. F.; Kormicki, J.; Daniel, A. V.; Hwang, J. K.; Beyer, C. J.; Wang, M. G.; Long, G. L.; Li, M.; Zhu, L. Y.; Gan, C. Y.; Ma, W. C.; Cole, J. D.; Aryaeinejad, R.; Dardenne, Y. X.; Drigert, M. W.; Rasmussen, J. O.; Asztalos, S.; Lee, I. Y.; Macchiavelli, A. O.; Chu, S. Y.; Gregorich, K. E.; Mohar, M. F.; Stoyer, M. A.; Lougheed, R. W.; Moody, K. J.; Wild, J. F.; Prussin, S. G.

    1998-04-01

    High spin states in neutron-rich odd-Z nuclei ^145,147La have been investigated from the study of prompt γ- rays in spontaneous fission of ^252Cf by using γ-γ- and γ-γ-γ- coincidence techniques. Alternating parity bands are extended up to spins I=(41/2) and I=(43/2) in ^145La and ^147La, respectively. Strong E1 transitions between the negative and positive parity bands give evidence for stable octupole deformation. The new higher spin levels give evidence for rotational enhancement of the stability of the octupole deformation. These collective bands show competition and co-existence between symmetric and asymmetric shapes in ^145La. Band crossing was found around hbarω≈ 0.26 ~0.30 MeV in both nuclei and these backbends are related to the alignment of two i_13/2 neutron from cranked shell model calculations.

  10. Observation of {chi}{sub bJ}(1P,2P) decays to light hadrons

    SciTech Connect

    Asner, D. M.; Edwards, K. W.; Reed, J.; Briere, R. A.; Tatishvili, G.; Vogel, H.; Onyisi, P. U. E.; Rosner, J. L.; Alexander, J. P.; Cassel, D. G.; Duboscq, J. E.; Ehrlich, R.; Fields, L.; Galik, R. S.; Gibbons, L.; Gray, R.; Gray, S. W.; Hartill, D. L.; Heltsley, B. K.; Hertz, D.

    2008-11-01

    Analyzing {upsilon}(nS) decays acquired with the CLEO detector operating at the CESR e{sup +}e{sup -} collider, we measure for the first time the product branching fractions B[{upsilon}(nS){yields}{gamma}{chi}{sub bJ}((n-1)P)]B[{chi}{sub bJ}(n-1)P){yields}X{sub i}] for n=2 and 3, where X{sub i} denotes, for each i, one of the 14 exclusive light-hadron final states for which we observe significant signals in both {chi}{sub bJ}(1P) and {chi}{sub bJ}(2P) decays. We also determine upper limits for the electric dipole (E1) transitions {upsilon}(3S){yields}{gamma}{chi}{sub bJ}(1P)

  11. Nuclear excitations and reaction mechanisms: a research proposal (renewal) and report of progress

    SciTech Connect

    Fallieros, S.; Levin, F.S.

    1981-07-31

    Research progress is reported on the following subjects: (1) diamagnetism, gauge transformations and sum rules, (2) quantal motion in an electric field, (3) a theorem concerning quadrupole absorption and scattering of photons, (4) excitation of natural parity states by Raman scattering in nuclei, (5) retarded E1 transitions and isoscaler giant dipole resonances, (6) low energy photon scattering from nuclei, (7) few-body models of nuclear reactions, (8) three- and four-nucleon configuration space calculations, (9) time-dependent few-body calculations, (10) atomic and molecular structure calculations, (11) bound state approximations, (12) extended Faddeev theory, (13) configuration-space techniques, and (14) time-dependent approach to scattering problems. (WHK)

  12. Structure of magnetic resonance in 87Rb atoms

    NASA Astrophysics Data System (ADS)

    Kozlov, A. N.; Zibrov, S. A.; Zibrov, A. A.; Yudin, V. I.; Taichenachev, A. V.; Yakovlev, V. P.; Tsygankov, E. A.; Zibrov, A. S.; Vassiliev, V. V.; Velichansky, V. L.

    2016-05-01

    Magnetic resonance at the F g = 1 rightleftarrows F e = 1 transition of the D 1 line in 87Rb has been studied with pumping and detection by linearly polarized radiation and detection at the double frequency of the radiofrequency field. The intervals of allowed values of the static and alternating magnetic fields in which magnetic resonance has a single maximum have been found. The structure appearing beyond these intervals has been explained. It has been shown that the quadratic Zeeman shift is responsible for the three-peak structure of resonance; the radiofrequency shift results in the appearance of additional extrema in resonance, which can be used to determine the relaxation constant Γ2. The possibility of application in magnetometry has been discussed.

  13. Evolution of octupole correlations in 123Ba

    NASA Astrophysics Data System (ADS)

    Chen, X. C.; Zhao, J.; Xu, C.; Hua, H.; Shneidman, T. M.; Zhou, S. G.; Wu, X. G.; Li, X. Q.; Zhang, S. Q.; Li, Z. H.; Liang, W. Y.; Meng, J.; Xu, F. R.; Qi, B.; Ye, Y. L.; Jiang, D. X.; Cheng, Y. Y.; He, C.; Sun, J. J.; Han, R.; Niu, C. Y.; Li, C. G.; Li, P. J.; Wang, C. G.; Wu, H. Y.; Li, Z. H.; Zhou, H.; Hu, S. P.; Zhang, H. Q.; Li, G. S.; He, C. Y.; Zheng, Y.; Li, C. B.; Li, H. W.; Wu, Y. H.; Luo, P. W.; Zhong, J.

    2016-08-01

    High-spin states of 123Ba have been studied via the 108Cd(19F,3 n p )123Ba fusion-evaporation reaction at a beam energy of 90 MeV. Several E 1 transitions linking the positive-parity ν (d5 /2+g7 /2) band and negative-parity ν h11 /2 band are observed in 123Ba for the first time. Evidence for the existence of octupole correlations in 123Ba is presented based on the systematic comparisons of the B (E 1 )/B (E 2 ) branching ratios and the energy displacements in odd-A Ba isotopes. The characteristics of octupole correlation in the odd-A Ba,125123 are explained by the state-of-the-art multidimensionally-constrained relativistic mean-field model and cluster model based on the dinuclear system concept.

  14. Measurement of lifetimes in {sup 46}V with the EUROBALL {gamma}-ray spectrometer

    SciTech Connect

    Jessen, K.; Moeller, O.; Dewald, A.; Brentano, P. von; Fitzler, A.; Jolie, J.; Saha, B.; Petkov, P.; Brandolini, F.; Gadea, A.; Lenzi, S. M.; De Angelis, G.; Farnea, E.; Napoli, D. R.; Gall, B. J. P.

    2006-08-15

    In {sup 46}V picosecond lifetimes were determined using the recoil distance Doppler-shift technique with the Cologne plunger device coupled to the EUROBALL IV spectrometer. The experiment was carried out using the {sup 24}Mg({sup 28}Si, {alpha}pn) reaction at 110 MeV at the Strasbourg VIVITRON accelerator. Subsequently the differential decay curve method in coincidence mode was employed to derive lifetimes for four excited states in the K{sup {pi}}=0{sup -} band. The resulting transition probabilities give a comparison of isospin allowed and forbidden E1 transitions, which clarifies the decay properties of the 2{sup -},T=0 state. Furthermore the B(E2) values within the K{sup {pi}}=0{sup -} band are discussed.

  15. Oscillator strengths and transition probabilities from the Breit–Pauli R-matrix method: Ne IV

    SciTech Connect

    Nahar, Sultana N.

    2014-09-15

    The atomic parameters–oscillator strengths, line strengths, radiative decay rates (A), and lifetimes–for fine structure transitions of electric dipole (E1) type for the astrophysically abundant ion Ne IV are presented. The results include 868 fine structure levels with n≤ 10, l≤ 9, and 1/2≤J≤ 19/2 of even and odd parities, and the corresponding 83,767 E1 transitions. The calculations were carried out using the relativistic Breit–Pauli R-matrix method in the close coupling approximation. The transitions have been identified spectroscopically using an algorithm based on quantum defect analysis and other criteria. The calculated energies agree with the 103 observed and identified energies to within 3% or better for most of the levels. Some larger differences are also noted. The A-values show good to fair agreement with the very limited number of available transitions in the table compiled by NIST, but show very good agreement with the latest published multi-configuration Hartree–Fock calculations. The present transitions should be useful for diagnostics as well as for precise and complete spectral modeling in the soft X-ray to infra-red regions of astrophysical and laboratory plasmas. -- Highlights: •The first application of BPRM method for accurate E1 transitions in Ne IV is reported. •Amount of atomic data (n going up to 10) is complete for most practical applications. •The calculated energies are in very good agreement with most observed levels. •Very good agreement of A-values and lifetimes with other relativistic calculations. •The results should provide precise nebular abundances, chemical evolution etc.

  16. Anharmonicity of the excited octupole band in actinides using supersymmetric quantum mechanics

    NASA Astrophysics Data System (ADS)

    Jolos, R. V.; von Brentano, P.; Casten, R. F.

    2013-09-01

    Background: Low-lying octupole collective excitations play an important role in the description of the structure of nuclei in the actinide region. Ground state alternating parity rotational bands combining both positive and negative parity states are known in several nuclei. However, only recently it has been discovered in 240Pu an excited positive parity rotational band having an octupole nature and demonstrating strong anharmonicity of the octupole motion in the band head energies.Purpose: To suggest a model describing both ground state and excited alternating parity bands, which includes a description of the anharmonic effects in the bandhead excitation energies and can be used to predict the energies of the excited rotational bands of octupole nature and the E1 transition probabilities.Methods: The mathematical technique of the supersymmetric quantum mechanics with a collective Hamiltonian depending only on the octupole collective variable which keeps axial symmetry is used to describe the ground state and excited alternating parity rotational bands.Results: The excitation energies of the states belonging to the lowest negative parity and the excited positive parity bands are calculated for 232Th, 238U, and 240Pu. The E1 transition matrix elements are also calculated for 240Pu.Conclusions: It is shown that the suggested model describes the excitation energies of the states of the lowest negative parity band with the accuracy around 10 keV. The anharmonicity in the bandhead energy of the excited positive parity band is described also. The bandhead energy of the excited positive parity band is described with the accuracy around 100 keV.

  17. Allowed and forbidden transition parameters for Fe XXII

    SciTech Connect

    Nahar, Sultana N.

    2010-01-15

    Radiative transitions for photo-excitations and de-excitations in Fe XXII are studied in the relativistic Breit-Pauli approximation. A comprehensive set of fine structure energy levels, oscillator strengths (f), line strengths (S), and radiative decay rates (A) for electric dipole (E1), same spin multiplicity and intercombination, fine structure transitions is presented. These are obtained from the first calculations in the close coupling approximation using the Breit-Pauli R-matrix method for this ion, all existing theoretical results having been obtained from various other atomic structure calculations. The present work obtains a set of 771 fine structure energy levels with n {<=} 10, l {<=} 9, and 1/2 {<=} J {<=} 17/2, only 52 of which have been observed. The f, S, and A values are reported for 70,372 allowed E1 transitions, exceeding by far those published previously. The calculated fine structure levels have been identified spectroscopically using a procedure based on quantum defect analysis. The energies agree with the available observed energies to within less than one to a few percent. The A values for E1 transitions are in good agreement with other existing values for most transitions. Using the atomic structure code SUPERSTRUCTURE (SS), S and A values are also presented for 38,215 forbidden transitions of the types electric quadrupole (E2), electric octupole (E3), magnetic dipole (M1), and magnetic quadrupole (M2) among 274 fine structure levels formed from 25 configurations with orbitals ranging from 1s to 4f. Some of these levels lie above the ionization limit and hence can form autoionizing lines. Such lines for 1s-2p K{sub {alpha}} transitions have been observed in experiments. The energies from the SS calculations agree with observed energies within a few percent. The A values for E2 and M1 transitions agree very well with the available values. The atomic parameters for both allowed and forbidden transitions should be applicable for diagnostics as

  18. Novel Manifestation of {alpha}-Clustering Structures: New '{alpha}+{sup 208}Pb' States in {sup 212}Po Revealed by Their Enhanced E1 Decays

    SciTech Connect

    Astier, A.; Porquet, M.-G.; Petkov, P.; Delion, D. S.; Schuck, P.

    2010-01-29

    Excited states in {sup 212}Po were populated by {alpha} transfer using the {sup 208}Pb({sup 18}O,{sup 14}C) reaction, and their deexcitation {gamma} rays were studied with the Euroball array. Several levels were found to decay by a unique E1 transition (E{sub {gamma}}<1 MeV) populating the yrast state with the same spin value. Their lifetimes were measured by the Doppler-shift attenuation method. The values, found in the range 0.1-1.4 ps, lead to very enhanced transitions, B(E1)=2x10{sup -2}-1x10{sup -3} W.u. These results are discussed in terms of an {alpha}-cluster structure which gives rise to states with non-natural-parity values, provided that the composite system cannot rotate collectively, as expected in the '{alpha}+{sup 208}Pb' case. Such states due to the oscillatory motion of the {alpha}-core distance are observed for the first time.

  19. Preparing the measurement of anapole moment in a chain of francium isotopes

    NASA Astrophysics Data System (ADS)

    Sheng, Dong

    This thesis presents the current status of the experimental efforts towards the measurement of the anapole moment in francium. The anapole moment is a parity violating, time-reversal conserving nuclear moment that arises from the weak interaction among nucleons. It is nuclear spin dependent and sensitive to the configuration of nuclear structure. Our experimental scheme is to perform a direct measurement of the anapole moment, by driving a parity forbidden E1 transition between ground hyperfine states in a series of francium isotopes inside a blue detuned dipole trap at the electric anti-node of a microwave cavity. We explore the tests using rubidium isotopes. The francium experiment will be moved to the ISAC radioactive beam facility of TRIUMF, Canada. During the preparation of the apparatus, we test the coherent control of the ground states via microwave and Raman beams, characterize the performance of a blue detuned dipole trap and study the atomic dynamics inside it using both classical and quantum methods. We also measure the lifetime of excited 5d states in Rb, with less than 1% uncertainty, to test and help to improve the current atomic structure theories.

  20. Preparation of the anapole moment measurement in a chain of isotopes

    NASA Astrophysics Data System (ADS)

    Sheng, Dong; Hood, Jonathan; Orozco, Luis

    2010-02-01

    We present the current status of the experimental effort towards the measurement of the anapole moment in different isotopes of francium. The anapole is a parity violating, time reversal conserving nuclear moment that arises from the weak interaction among nucleons, and should be sensitive to the changes in the nuclear structure configuration among the isotopes. The anapole is a unique probe of the weak interaction in the presence of the strong interaction. The system is currently being tested with rubidium and we have analyzed the sensitivity to measurements with a chain of Rb isotopes. Our experimental scheme involves a collection of cold atoms in a blue-detuned dipole trap located at the anti-node of a microwave cavity. The standing wave would drive a parity forbidden E1 transition between hyperfine ground states, interfering with an allowed transition. The rate of transitions depends on the positive or negative handedness of the apparatus and the measurement of their difference is proportional to the anapole moment. The experiment will use of the ISAC radioactive beam facility at TRIUMF. )

  1. Theoretical study on K, L, and M X-ray transition energies and rates of neptunium and its ions

    NASA Astrophysics Data System (ADS)

    Ismail Abdalla, Saber; Dong, Chen-Zhong; Wang, Xiang-Li; Zhou, Wei-Dong; Wu, Zhong-Wen

    2014-02-01

    The transition energies and electric dipole (E1) transition rates of the K, L, and M lines in neutral Np have been theoretically determined from the MultiConfiguration Dirac—Fock (MCDF) method. In the calculations, the contributions from Breit interaction and quantum electrodynamics (QED) effects (vacuum polarization and self-energy), as well as nuclear finite mass and volume effects, are taken into account. The calculated transition energies and rates are found to be in good agreement with other experimental and theoretical results. The accuracy of the results is estimated and discussed. Furthermore, we calculated the transition energies of the same lines radiating from the decaying transitions of the K-, L-, and M-shell hole states of Np ions with the charge states Np1+ to Np6+ for the first time. We found that for a specific line, the corresponding transition energies relating to all the Np ions are almost the same; it means the outermost electrons have a very small influence on the inner-shell transition processes.

  2. Proton pygmy resonances: Predictions for N = 20 isotones

    NASA Astrophysics Data System (ADS)

    Kim, Y.; Papakonstantinou, P.

    2016-06-01

    We study theoretically the low-energy electric-dipole response of N = 20 isotones. We present results from a quasiparticle random-phase approximation (QRPA) and a continuum random-phase approximation (CRPA), and we compare them with results for the mirror Z = 20 nuclei. According to our analysis, enhanced E1 strength is expected energetically well below the giant dipole resonance in the proton-rich isotones. Large amounts of E1 strength in the asymmetric N = 20 isotones are predicted, markedly unlike their equally asymmetric Z = 20 mirror nuclei, pointing unambiguously to the role of structural effects such as loose binding. A proton-skin oscillation could develop especially in 46Fe . The isoscalar response is predicted strong in all isotones. The proper description of non-localized threshold transitions and the nucleon effective mass in mean-field treatments may affect theoretical predictions. We call for systematic theoretical investigations to quantify the role of bulk-matter properties in anticipation of measurements of E1 transitions in proton-rich nuclei.

  3. Two-quasiparticle isomer, E1 hindrances and residual interactions in {sup 172}Tm

    SciTech Connect

    Hughes, R. O.; Lane, G. J.; Dracoulis, G. D.; Kibedi, T.; Nieminen, P.; Watanabe, H.

    2008-04-15

    The structure of the neutron-rich nucleus {sup 172}Tm has been studied using incomplete fusion of {sup 7}Li on an {sup 170}Er target at 30 MeV. A 190-{mu}s isomer at an excitation energy of 476 keV was identified using chopped beams and {gamma}-ray spectroscopy. The isomer decays with very inhibited E1 transitions to the rotational bands based on the parallel and antiparallel couplings of the {nu}5/2{sup -}[512] x {pi}1/2{sup +}[411] configuration, the latter (K{sup {pi}}=2{sup -}) being the ground state. The isomeric state has been assigned J{sup {pi}}=6{sup +}, arising from the energetically favored (parallel) coupling of the {nu}5/2{sup -}[512] x {pi}7/2{sup -}[523] configuration. The proton-neutron residual interaction was deduced for the configuration of the isomeric state and is found to agree with previous empirical studies.

  4. Higher-spin structures in 21F and 25Na

    NASA Astrophysics Data System (ADS)

    VonMoss, J. M.; Tabor, S. L.; Tripathi, Vandana; Volya, A.; Abromeit, B.; Bender, P. C.; Caussyn, D. D.; Dungan, R.; Kravvaris, K.; Kuchera, M. P.; Lubna, R.; Miller, S.; Parker, J. J.; Tai, P.-L.

    2015-09-01

    Excited states were investigated in 21F and 25Na using the 9Be(14C,p n γ ) reaction at 30, 35, and 45 MeV and the 9Be(18O,p n γ ) reaction at 35 MeV. Protons were detected and identified in an E -Δ E telescope at 0∘ in coincidence with one or more γ radiations in the FSU Compton-suppressed Ge detector array. Many new levels and electromagnetic decays were observed, especially among the higher spin states. Angular distributions and mean lifetimes were measured wherever possible in both nuclei. The energy levels of the positive-parity states in the two nuclei agree rather well with shell model calculations using both the USDA and WBP interactions up to the highest spins observed of 13 /2 ℏ . Both a weak coupling approximation and shell model calculations using the WBP interaction generally reproduce the negative-parity states in 21F. The shell model calculations reproduce relatively well the measured M 1 and E 2 transitions in both nuclei, but overpredict the parity-changing E 1 transitions in 21F, the only nucleus in which negative-parity states were observed in the present experiment.

  5. Searching for space-time variation of the fine structure constant using QSO spectra: overview and future prospects

    NASA Astrophysics Data System (ADS)

    Berengut, J. C.; Dzuba, V. A.; Flambaum, V. V.; King, J. A.; Kozlov, M. G.; Murphy, M. T.; Webb, J. K.

    Theories unifying gravity with other interactions suggest the possibility of spatial and temporal variation of fundamental ``constants'' in the Universe. Using quasar absorption systems we can probe the value of the fine-structure constant, alpha = e2/hbar c, over the history of the universe. Previous studies of three independent samples of data, containing 143 absorption systems spread from 2 to 10 billion years after big bang, hint that alpha was smaller 7 - 11 billion years ago. However competing studies show no such alpha -variation. The studies can be improved by utilising more atomic transitions that are seen in quasar spectra, however in many cases this is hampered by a lack of accurate laboratory frequency measurements. The aim of this paper is to provide a compilation of transitions of importance to the search for alpha variation. They are E1 transitions from the ground state in several different atoms and ions, with wavelengths ranging from around 900 - 6000 Å, and require an accuracy of better than 10-4 Å. We also discuss isotope shift measurements that are needed in order to resolve systematic effects in the study. Researchers who are interested in performing these measurements should contact the authors directly.

  6. Gamma-ray spectroscopy of the ^238U shape isomer.

    NASA Astrophysics Data System (ADS)

    Hauschild, K.; Bauer, R. W.; Becker, J. A.; Bernstein, L. A.; Britt, H. C.; Younes, W.; Fotiades, N.

    1997-04-01

    The γ--rays de--exciting the fission isomers ^236U and ^238U are very different despite similar excitation energies, lifetimes and low--lying yrast structures. The predominant γ--ray decay branch for ^236U^m is a 1.783 MeV E1 transition (J. Schirmer, et al., Phys. Rev. Lett. 63), 2196 (1989); and Refs. therein., while ^238U^m is depopulated by a 2.513 MeV E2 γ-ray (J. Kantele, et al., Phys. Rev. C 29), 1693 (1984); and Refs. therein.. Approximately 65% of the γ--branch de-exciting ^238U^m remains to be identified. To determine the multipolarity of the remaining γ-branch out of ^238U^m we used the Gammasphere array at LBNL and the ^238U(d,pn) reaction at Ed = 20 MeV. A search for excited states in the 2^nd well has also been conducted. Preliminary results will be presented, and the γ--decay of the shape isomers discussed in context with the recent A ~190 SD decay--out results (T. L. Khoo, et al., Phys. Rev. Lett. 76), 1583 (1996); A. Lopez-Martens, et al., Phys. Lett. B380, 18 (1996); K. Hauschild, et al., submitted to Phys. Rev. C (1996)..

  7. Continuum {gamma} rays feeding normal and superdeformed states in Gd nuclei

    SciTech Connect

    Zhu, L.H.; Cinausero, M.; de Angelis, G.; De Poli, M.; Gadea, A.; Napoli, D.R.; Bazzacco, D.; Lunardi, S.; Viesti, G.; Petrache, C.M.; Rossi Alvarez, C.

    1997-03-01

    The feeding mechanism of the superdeformed bands in {sup 147}Gd and {sup 148}Gd has been studied via the {sup 124}Sn + {sup 29}Si reaction at a beam energy of 157 MeV. Using the BGO inner ball of the GASP array, high-energy {gamma} rays have been detected in coincidence with discrete transitions deexciting normal-deformed (ND) and superdeformed (SD) states in the final product nuclei. The slope of the measured high-energy {gamma}-ray spectra depends strongly on the number of emitted neutrons and is somewhat lower for spectra in coincidence with SD bands than for those in coincidence with ND structures. Both observations are qualitatively reproduced by statistical model Monte Carlo calculations, which point out the importance of angular momentum effects in the emission of energetic {gamma} rays. The present data exclude the enhanced population of SD bands when fed through high-energy E1 transitions. {copyright} {ital 1997} {ital The American Physical Society}

  8. Splitting of the Pygmy Dipole Resonance

    NASA Astrophysics Data System (ADS)

    Endres, J.; Butler, P.; Harakeh, M. N.; Harissopulos, S.; Herzberg, R.-D.; Krücken, R.; Lagoyannis, A.; Litvinova, E.; Pietralla, N.; Ponomarev, V. Yu.; Popescu, L.; Ring, P.; Savran, D.; Scheck, M.; Sonnabend, K.; Stoica, V. I.; Wörtche, H. J.; Zilges, A.

    2011-10-01

    In recent years investigations have been made to study the electric Pygmy Dipole Resonance (PDR) systematically, mainly in semi-magic nuclei. For this purpose the well understood high resolution (γ,γ') photon scattering method is used. In complementary (α,α'γ) coincidence experiments at Eα = 136 MeV a similar γ-energy resolution and a high selectivity to E1 transitions can be obtained at the Big-Bite Spectrometer (BBS) at KVI, Groningen. In comparison to the (γ,γ') method a structural splitting of the PDR is observed in the N = 82 nuclei 138Ba and 140Ce and in the Z = 50 nucleus 124Sn. The low energy part is excited in (γ,γ') as well as in (α,α'γ) while the high energy part is observed in (γ,γ') only. The experimental results together with theoretical QPM and RQTBA calculations on 124Sn which are able to reproduce the splitting of the PDR qualitatively are presented. The low-lying group of Jπ = 1- states seem to represent the more isoscalar neutron-skin oscillation of the PDR while the energetically higher-lying states seemingly belong to the transitional region between the PDR and the isovector Giant Dipole Resonance (IVGDR).

  9. Splitting of the Pygmy Dipole Resonance

    SciTech Connect

    Endres, J.; Zilges, A.; Butler, P.; Herzberg, R.-D.; Scheck, M.; Harakeh, M. N.; Harissopulos, S.; Lagoyannis, A.; Kruecken, R.; Ring, P.; Litvinova, E.; Pietralla, N.; Ponomarev, V. Yu.; Sonnabend, K.; Popescu, L.; Savran, D.; Stoica, V. I.; Woertche, H. J.

    2011-10-28

    In recent years investigations have been made to study the electric Pygmy Dipole Resonance (PDR) systematically, mainly in semi-magic nuclei. For this purpose the well understood high resolution ({gamma},{gamma}') photon scattering method is used. In complementary ({alpha},{alpha}'{gamma}) coincidence experiments at E{sub {alpha}} = 136 MeV a similar {gamma}-energy resolution and a high selectivity to E1 transitions can be obtained at the Big-Bite Spectrometer (BBS) at KVI, Groningen. In comparison to the ({gamma},{gamma}') method a structural splitting of the PDR is observed in the N = 82 nuclei {sup 138}Ba and {sup 140}Ce and in the Z = 50 nucleus {sup 124}Sn. The low energy part is excited in ({gamma},{gamma}') as well as in ({alpha},{alpha}'{gamma}) while the high energy part is observed in ({gamma},{gamma}') only. The experimental results together with theoretical QPM and RQTBA calculations on {sup 124}Sn which are able to reproduce the splitting of the PDR qualitatively are presented. The low-lying group of J{sup {pi}} = 1{sup -} states seem to represent the more isoscalar neutron-skin oscillation of the PDR while the energetically higher-lying states seemingly belong to the transitional region between the PDR and the isovector Giant Dipole Resonance (IVGDR).

  10. Higher-spin structures in F21 and Na25

    DOE PAGESBeta

    VonMoss, J. M.; Tabor, S. L.; Tripathi, Vandana; Volya, A.; Abromeit, B.; Bender, P. C.; Caussyn, D. D.; Dungan, R.; Kravvaris, K.; Kuchera, M. P.; et al

    2015-09-03

    We investigated excited states in F-21 and Na-25 using the Be-9(C-14, pn gamma) reaction at 30, 35, and 45 MeV and the Be-9(O-18, pn gamma) reaction at 35 MeV. We also detected protons and identified in an E-Delta E telescope at 0 degrees in coincidence with one or more gamma radiations in the FSU Compton-suppressed Ge detector array. Many new levels and electromagnetic decays were observed, especially among the higher spin states. Angular distributions and mean lifetimes were measured wherever possible in both nuclei. The energy levels of the positive-parity states in the two nuclei agree rather well with shellmore » model calculations using both the USDA and WBP interactions up to the highest spins observed of 13/2 h. Both a weak coupling approximation and shell model calculations using the WBP interaction generally reproduce the negative-parity states in F-21. Finally, the shell model calculations reproduce relatively well the measured M1 and E2 transitions in both nuclei, but overpredict the parity-changing E1 transitions in F-21, the only nucleus in which negative-parity states were observed in the present experiment.« less

  11. Quasiparticle-random-phase approximation treatment of the transverse wobbling mode reconsidered

    NASA Astrophysics Data System (ADS)

    Frauendorf, S.; Dönau, F.

    2015-12-01

    The quasiparticle-random-phase approximation is used to study the properties of the wobbling bands in 163Lu. Assuming that the wobbling mode represents pure isoscalar orientation oscillations results in too low wobbling frequencies and transition probabilities between the one- and zero-phonon wobbling bands that are strongly collective but yet too weak for B (E2 ) out and too strong for B (M1 ) out . The inclusion of an LL interaction, which couples the wobbling mode to the scissors mode, generates the right upshift of the wobbling frequencies and the right suppression of the B (M1 ) out values toward the experimental values, but does not change the B (E2 ) out values. In analogy to the quenching of low-energy E 1 transition by coupling to the isovector giant dipole resonance, a general reduction of the M 1 transitions between quasiparticle configurations caused by coupling to the scissors mode is suggested. The small B (E2 ) out values are related to small triaxiality of the density distribution, which is found by all mean field calculations for the triaxial strongly deformed nuclei in the mass 160 region.

  12. Decay spectroscopy of 160Sm: The lightest four-quasiparticle K isomer

    NASA Astrophysics Data System (ADS)

    Patel, Z.; Podolyák, Zs.; Walker, P. M.; Regan, P. H.; Söderström, P.-A.; Watanabe, H.; Ideguchi, E.; Simpson, G. S.; Nishimura, S.; Browne, F.; Doornenbal, P.; Lorusso, G.; Rice, S.; Sinclair, L.; Sumikama, T.; Wu, J.; Xu, Z. Y.; Aoi, N.; Baba, H.; Bello Garrote, F. L.; Benzoni, G.; Daido, R.; Dombrádi, Zs.; Fang, Y.; Fukuda, N.; Gey, G.; Go, S.; Gottardo, A.; Inabe, N.; Isobe, T.; Kameda, D.; Kobayashi, K.; Kobayashi, M.; Komatsubara, T.; Kojouharov, I.; Kubo, T.; Kurz, N.; Kuti, I.; Li, Z.; Liu, H. L.; Matsushita, M.; Michimasa, S.; Moon, C.-B.; Nishibata, H.; Nishizuka, I.; Odahara, A.; Şahin, E.; Sakurai, H.; Schaffner, H.; Suzuki, H.; Takeda, H.; Tanaka, M.; Taprogge, J.; Vajta, Zs.; Xu, F. R.; Yagi, A.; Yokoyama, R.

    2016-02-01

    The decay of a new four-quasiparticle isomeric state in 160Sm has been observed using γ-ray spectroscopy at the RIBF, RIKEN. The four-quasiparticle state is assigned a 2 π ⊗ 2 ν π5/2- [ 532 ], π5/2+ [ 413 ], ν5/2- [ 523 ], ν7/2+ [ 633 ] configuration. The half-life of this (11+) state is measured to be 1.8(4) μs. The (11+) isomer decays into a rotational band structure, based on a (6-) ν5/2- [ 523 ] ⊗ ν7/2+ [ 633 ] bandhead, consistent with the gK -gR values. This decays to a (5-) two-proton quasiparticle state, which in turn decays to the ground state band. Potential energy surface and blocked-BCS calculations were performed in the deformed midshell region around 160Sm. They reveal a significant influence from β6 deformation and that 160Sm is the best candidate for the lightest four-quasiparticle K isomer to exist in this region. The relationship between reduced hindrance and isomer excitation energy for E1 transitions from multiquasiparticle states is considered with the new data from 160Sm. The E1 data are found to agree with the existing relationship for E2 transitions.

  13. Evidence for octupole vibration in the superdeformed well of {sup 190}Hg from eurogam

    SciTech Connect

    Crowell, B.; Carpenter, M.P.; Janssens, R.V.F.

    1995-08-01

    Gammasphere experiments in 1993-94 brought to light the existence of an excited superdeformed (SD) band in {sup 190}Hg with the unusual property of decaying entirely to the lowest (yrast) SD band over 3-4 transitions, rather than to the normally deformed states as is usually the case in the A {approximately} 150 and A {approximately} 190 regions of superdeformation. Although M1 transitions between signature-partner SD bands were previously observed in {sup 193}Hg, no such mechanism was available to explain the situation in the even-even nucleus {sup 190}Hg, whose yrast SD band has no signature partner. The best explanation appears to lie in long-standing theoretical predictions that the SD minimum in the potential energy surface would be quite soft with respect to octupole vibrations. This would lead to enhanced E1 transitions connecting the one-phonon and zero-phonon states. The data and this interpretation were published. A shortcoming of the Gammasphere experiments was that they did not allow the definitive measurement of the energies of the gamma-ray transitions connecting the two bands, due to the very weak population of the excited band ({approximately}0.05% of the {sup 190}Hg channel) and also partly, we believed, to the angular distributions of the transitions, which were peaked near 90 degrees, where Gammasphere had few detectors.

  14. Coherent quadrupole-octupole modes and split parity-doublet spectra in odd-A nuclei

    SciTech Connect

    Minkov, N.; Drenska, S.; Yotov, P.; Lalkovski, S.; Bonatsos, D.; Scheid, W.

    2007-09-15

    A collective model describing coherent quadrupole-octupole oscillations and rotations with a Coriolis coupling between the even-even core and the unpaired nucleon is applied to odd nuclei. The particle-core coupling provides a parity-doublet structure of the spectrum, whereas the quadrupole-octupole motion leads to a splitting of the doublet energy levels. The formalism successfully reproduces the split parity-doublet spectra and the attendant B(E1) and B(E2) transition probabilities in a wide range of odd-A nuclei. It provides estimations for the influence of the Coriolis interaction on the collective motion and subsequently for the value of angular momentum projection K on which the spectrum is built. The analysis of the energy splitting and B(E1) transition probabilities between opposite parity counterparts suggests degenerate doublet structures at high angular momenta. The study provides information about the evolution of quadrupole-octupole collectivity in odd-mass nuclei.

  15. Resonance parameters of the first 1/2+ state in Be9 and astrophysical implications

    NASA Astrophysics Data System (ADS)

    Burda, O.; von Neumann-Cosel, P.; Richter, A.; Forssén, C.; Brown, B. A.

    2010-07-01

    Spectra of the Be9(e,e') reaction have been measured at the Superconducting Darmstadt Electron Linear Accelerator at an electron energy of E0=73 MeV and scattering angles of 93° and 141° with high-energy resolution up to excitation energies of Ex=8 MeV. The astrophysically relevant resonance parameters of the first excited 1/2+ state of Be9 have been extracted in a one-level approximation of R-matrix theory, resulting in resonance energy ER=1.748(6) MeV and width ΓR=274(8) keV, which are in good agreement with the latest Be9(γ,n) experiment but with considerably improved uncertainties. However, the reduced B(E1) transition strength deduced from an extrapolation of the (e,e') data to the photon point is smaller by a factor of two. Implications of the new results for possible production of C12 in neutron-rich astrophysical scenarios are discussed.

  16. Resonant excitation channels in the 3d10-3d94s and 3d10-3d94p transitions of nickel-like Mo14+ and Zr12+

    NASA Astrophysics Data System (ADS)

    Fournier, K. B.; Goldstein, W. H.; May, M.; Finkenthal, M.; Terry, J. L.

    1996-05-01

    At energies below the threshold for direct electron impact excitation, resonant excitations can make a significant contribution to the total excitation rate of a given energy level. In this paper, the rates of resonant excitation into the levels of the 3d94s and 3d94p configurations of Mo14+ have been calculated using a fully relativistic, multiconfiguration atomic structure code and detailed accounting of energy levels. By including the effects of resonant excitations in collisional-radiative models for the spectrum of Ni I-like Mo14+ and (by isoelectronic scaling) Zr12+, the ratio of the emissivity of the 3d10-4d94s E2 transitions to the emissivity of the 3d10-3d94p E1 transitions is greatly enhanced, and sensitivity to electron temperature in the ratio is introduced. This ratio is density sensitive for ne>=1013 cm-3, and therefore, given knowledge of either local temperature or density conditions, the E2-E1 ratio can serve as a diagnostic for local conditions in magnetically confined fusion plasmas. The current work demonstrates the need to include resonant excitations in collisional-radiative models of the soft x-ray emission of nickel-like ions. Good agreement is found between measurements of E1 and E2 line brightness ratios made in a tokamak plasma, and the predictions of collisional-radiative models in the present work.

  17. Hyperfine-induced electric dipole contributions to the electric octupole and magnetic quadrupole atomic clock transitions

    NASA Astrophysics Data System (ADS)

    Dzuba, V. A.; Flambaum, V. V.

    2016-05-01

    Hyperfine-induced electric dipole contributions may significantly increase probabilities of otherwise very weak electric octupole and magnetic quadrupole atomic clock transitions (e.g., transitions between s and f electron orbitals). These transitions can be used for exceptionally accurate atomic clocks, quantum information processing, and the search for dark matter. They are very sensitive to new physics beyond the standard model, such as temporal variation of the fine-structure constant, the Lorentz invariance, and Einstein equivalence principle violation. We formulate conditions under which the hyperfine-induced electric dipole contribution dominates and perform calculations of the hyperfine structure and E3, M2 and the hyperfine-induced E1 transition rates for a large number of atoms and ions of experimental interest. Due to the hyperfine quenching the electric octupole clock transition in +173Yb is 2 orders of magnitude stronger than that in currently used +171Yb. Some enhancement is found in 13+143Nd, 14+149Pm, 14+147Sm, and 15+147Sm ions.

  18. Higher-spin structures in F21 and Na25

    SciTech Connect

    VonMoss, J. M.; Tabor, S. L.; Tripathi, Vandana; Volya, A.; Abromeit, B.; Bender, P. C.; Caussyn, D. D.; Dungan, R.; Kravvaris, K.; Kuchera, M. P.; Lubna, R.; Miller, S.; Parker, J. J.; Tai, P. -L.

    2015-09-03

    We investigated excited states in F-21 and Na-25 using the Be-9(C-14, pn gamma) reaction at 30, 35, and 45 MeV and the Be-9(O-18, pn gamma) reaction at 35 MeV. We also detected protons and identified in an E-Delta E telescope at 0 degrees in coincidence with one or more gamma radiations in the FSU Compton-suppressed Ge detector array. Many new levels and electromagnetic decays were observed, especially among the higher spin states. Angular distributions and mean lifetimes were measured wherever possible in both nuclei. The energy levels of the positive-parity states in the two nuclei agree rather well with shell model calculations using both the USDA and WBP interactions up to the highest spins observed of 13/2 h. Both a weak coupling approximation and shell model calculations using the WBP interaction generally reproduce the negative-parity states in F-21. Finally, the shell model calculations reproduce relatively well the measured M1 and E2 transitions in both nuclei, but overpredict the parity-changing E1 transitions in F-21, the only nucleus in which negative-parity states were observed in the present experiment.

  19. Octupole deformation in 144,146Ba measured by Coulomb excitation of radioactive beams

    NASA Astrophysics Data System (ADS)

    Bucher, Brian; Zhu, Shaofei; ANL, LBNL, LLNL, Rochester, Florida State, Liverpool, Maryland, Notre Dame, Ohio, W. Scotland Collaboration

    2015-10-01

    The exotic, neutron-rich 144Ba (t1 / 2 = 11.5 s) and 146Ba (t1 / 2 = 2.2 s) nuclei are expected to exhibit some of the strongest octupole correlations in A < 200 systems. Up to now, evidence for such strong octupole correlations has been inferred from observations of low-lying negative-parity states and from the interleaving of positive- and negative-parity levels in the ground-state band. However, the E1 transition strengths are very different in these two nuclei, with two orders of magnitude reduction in 146Ba. In this experiment, we measure the octupole strength directly by Coulomb excitation of post-accelerated 144,146Ba beams produced at CARIBU using CHICO2 and GRETINA. In 144Ba, we found B(E3;3 -->0) = 48(-34+ 25) W.u., a value considerably larger than theoretical predictions, while preliminary results for 146Ba are also indicative of strong octupole collectivity. The experimental conditions, the analysis, and the results from these challenging new measurements will be presented. This work is supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357 (ANL), DE-AC02-05CH11231 (LBNL, GRETINA), DOE DE-AC52-07NA27344 (LLNL), and NSF.

  20. High spin states in {sup 151,153}Pr, {sup 157}Sm, and {sup 93}Kr

    SciTech Connect

    Hwang, J. K.; Ramayya, A. V.; Hamilton, J. H.; Liu, S. H.; Brewer, N. T.; Luo, Y. X.; Rasmussen, J. O.; Zhu, S. J.; Donangelo, R.

    2010-09-15

    High spin states are observed for the first time in the neutron-rich nuclei {sup 151,153}Pr, {sup 157}Sm, and {sup 93}Kr from the spontaneous fission of {sup 252}Cf. Twenty new transitions in {sup 151}Pr, twelve in {sup 153}Pr, five in {sup 157}Sm, and four in {sup 93}Kr were identified by using x-ray(Pr/Sm)-{gamma}-{gamma} and {gamma}-{gamma}-{gamma} triple coincidences. From the measured total internal conversion coefficients {alpha}{sub T} of four low-energy transitions in {sup 151,153}Pr, we determine that two bands in each nucleus have opposite parity. The interlacing E1 transitions between the bands suggest a form of parity doubling in {sup 151,153}Pr. New bands in {sup 157}Sm and {sup 93}Kr are reported. The half-life of the 354.8 keV state in {sup 93}Kr is measured to be 10(2) ns.

  1. Direct evidence of octupole deformation in neutron-rich 144Ba

    DOE PAGESBeta

    Bucher, B.; Zhu, S.; Wu, C. Y.; Janssens, R. V. F.; Cline, D.; Hayes, A. B.; Albers, M.; Ayangeakaa, A. D.; Butler, P. A.; Campbell, C. M.; et al

    2016-03-17

    Here, the neutron-rich nucleus 144Ba (t1/2 = 11.5 s) is expected to exhibit some of the strongest octupole correlations among nuclei with mass numbers A less than 200. Until now, indirect evidence for such strong correlations has been inferred from observations such as enhanced E1 transitions and interleaving positive- and negative-parity levels in the ground-state band. In this experiment, the octupole strength was measured directly by sub-barrier, multistep Coulomb excitation of a post-accelerated 650-MeV 144Ba beam on a 1.0–mg/cm2 208Pb target. The measured value of the matrix element, < 31–∥M(E3)∥01+ >= 0.65(+17–23) eb3/2, corresponds to a reduced B(E3) transition probabilitymore » of 48(+25–34) W.u. This result represents an unambiguous determination of the octupole collectivity, is larger than any available theoretical prediction, and is consistent with octupole deformation.« less

  2. Towards microscopic ab initio calculations of astrophysical S-factors

    NASA Astrophysics Data System (ADS)

    Neff, Thomas; Feldmeier, Hans; Langanke, Karlheinz

    2011-04-01

    Low energy capture cross sections are calculated within a microscopic many-body approach using an effective Hamiltonian derived from the Argonne V18 potential. The dynamics is treated within Fermionic Molecular Dynamics (FMD) which uses a Gaussian wave-packet basis to represent the many-body states. A phase-shift equivalent effective interaction derived within the Unitary Correlation Operator Method (UCOM) that treats explicitly short-range central and tensor correlations is employed. As a first application the 3He(α,γ)7Be reaction is presented. Within the FMD approach the microscopic many-body wave functions of the 3/2- and 1/2- bound states in 7Be as well as the many-body scattering states in the 1/2+, 3/2+ and 5/2+ channels are calculated as eigenstates of the same microscopic effective Hamiltonian. Finally the S-factor is calculated from E1 transition matrix elements between the many-body scattering and bound states. For 3He(α, γ)7Be the S-factor agrees very well, both in absolute normalization and energy dependence, with the recent experimental data from the Weizmann, LUNA, Seattle and ERNA experiments. For the 3H(α, γ)7Li reaction the calculated S-factor is about 15% above the data.

  3. Resonance behavior of internal conversion coefficients at low γ-ray energy

    NASA Astrophysics Data System (ADS)

    Trzhaskovskaya, M. B.; Kibédi, T.; Nikulin, V. K.

    2010-02-01

    A resonance-like structure of internal conversion coefficients (ICCs) at low γ-ray energy (≲100 keV) is studied. Our calculations revealed new, previously unknown resonance minima in the energy dependence of ICCs for the ns shells at E2-E5 transitions. The resonances are the most defined for ICCs in light and medium elements with Z≲ 50. It is shown that ICCs may have up to four resonances for outer shells while it has been assumed so far that only one resonance exists. Well-pronounced resonances in ICCs at E1 transition were discovered for the ns shells with n⩾2 as well as for the np shells with n⩾3 and the nd shells with n⩾4 of all elements up to superheavy ones. Simple expressions for approximate values of the E1 resonance energy were obtained which are of importance for determination of the resonance energy range where the interpolation of ICCs taken from tables or databases may give significant errors. The occurrence of resonances in ICCs is explained by vanishing conversion matrix elements under changes of sign. The peculiarities of the behavior of the matrix elements and electron wave functions at the resonance energy are considered. Available experimental ICCs for electric transitions with energies near the expected position of resonances satisfactory agree with our calculations.

  4. Discovery of low-lying E1 and M1 strengths in {sup 232}Th

    SciTech Connect

    Adekola, A. S.; Hammond, S. L.; Hill, A.; Karwowski, H. J.; Angell, C. T.; Howell, C. R.; Kwan, E.; Kelley, J. H.

    2011-03-15

    Properties of low-energy dipole states in {sup 232}Th have been investigated with the nuclear resonance fluorescence technique. The present work used monoenergetic {gamma}-ray beams at energies of 2-4 MeV from the high-intensity {gamma}-ray source at Triangle Universities Nuclear Laboratory. Over 40 transitions corresponding to deexcitation to the ground state and first excited state were observed for the first time. Excitation energies, integrated cross sections, decay widths, branching ratios, and transition strengths for those states in {sup 232}Th were determined and compared with quasiparticle random-phase-approximation calculations. A large number of E1 transitions were observed for the first time in actinide nuclei with summed strength of 3.28(69)x10{sup -3} e{sup 2} fm{sup 2}. The observed summed M1 strength of 4.26(63){mu}{sub N}{sup 2} is in good agreement with the other actinides and with the systematics of the scissors mode in deformed rare-earth nuclei.

  5. Identification of isomeric states in the N=73 neutron-deficient nuclei 132Pr and 130La

    NASA Astrophysics Data System (ADS)

    Taylor, M. J.; Alharshan, G. A.; Cullen, D. M.; Procter, M. G.; Lumley, N. M.; Grahn, T.; Greenlees, P. T.; Hauschild, K.; Herzan, A.; Jakobsson, U.; Jones, P.; Julin, R.; Juutinen, S.; Ketelhut, S.; Leino, M.; Lopez-Martens, A.; Nieminen, P.; Partanen, J.; Peura, P.; Rahkila, P.; Rinta-Antila, S.; Ruotsalainen, P.; Sandzelius, M.; Sarén, J.; Scholey, C.; Sorri, J.; Stolze, S.; Uusitalo, J.; Xu, F. R.; Bai, Z. J.

    2012-10-01

    Decays from isomeric states in the neutron-deficient N=73 nuclei 132Pr and 130La have been observed for the first time. Half-lives of 486(70) ns and 2.46(4) μs were measured for two isomeric states in 132Pr. The decay from the 486 ns (8-) isomer has been interpreted as a hindered E1 transition from the bandhead state of the excited πh11/2⊗νg7/2 configuration. The decay from the 2.5 μs (8+) isomer is consistent with the Weisskopf estimate for a low-energy E2 transition. An analogous 0.74(3) μs decay from an (8+) isomer in the neighboring isotone 130La has also been observed which similarly can be explained if the transition has E2 character. The Weisskopf interpretation for the isomer hindrance is strengthened by the lack of evidence for shape or K isomerism due to the γ-soft shapes predicted by configuration-constrained potential-energy-surface calculations.

  6. Direct Evidence of Octupole Deformation in Neutron-Rich ^{144}Ba.

    PubMed

    Bucher, B; Zhu, S; Wu, C Y; Janssens, R V F; Cline, D; Hayes, A B; Albers, M; Ayangeakaa, A D; Butler, P A; Campbell, C M; Carpenter, M P; Chiara, C J; Clark, J A; Crawford, H L; Cromaz, M; David, H M; Dickerson, C; Gregor, E T; Harker, J; Hoffman, C R; Kay, B P; Kondev, F G; Korichi, A; Lauritsen, T; Macchiavelli, A O; Pardo, R C; Richard, A; Riley, M A; Savard, G; Scheck, M; Seweryniak, D; Smith, M K; Vondrasek, R; Wiens, A

    2016-03-18

    The neutron-rich nucleus ^{144}Ba (t_{1/2}=11.5  s) is expected to exhibit some of the strongest octupole correlations among nuclei with mass numbers A less than 200. Until now, indirect evidence for such strong correlations has been inferred from observations such as enhanced E1 transitions and interleaving positive- and negative-parity levels in the ground-state band. In this experiment, the octupole strength was measured directly by sub-barrier, multistep Coulomb excitation of a post-accelerated 650-MeV ^{144}Ba beam on a 1.0-mg/cm^{2} ^{208}Pb target. The measured value of the matrix element, ⟨3_{1}^{-}∥M(E3)∥0_{1}^{+}⟩=0.65(+17/-23) eb^{3/2}, corresponds to a reduced B(E3) transition probability of 48(+25/-34)  W.u. This result represents an unambiguous determination of the octupole collectivity, is larger than any available theoretical prediction, and is consistent with octupole deformation. PMID:27035298

  7. Direct Evidence of Octupole Deformation in Neutron-Rich 144Ba

    NASA Astrophysics Data System (ADS)

    Bucher, B.; Zhu, S.; Wu, C. Y.; Janssens, R. V. F.; Cline, D.; Hayes, A. B.; Albers, M.; Ayangeakaa, A. D.; Butler, P. A.; Campbell, C. M.; Carpenter, M. P.; Chiara, C. J.; Clark, J. A.; Crawford, H. L.; Cromaz, M.; David, H. M.; Dickerson, C.; Gregor, E. T.; Harker, J.; Hoffman, C. R.; Kay, B. P.; Kondev, F. G.; Korichi, A.; Lauritsen, T.; Macchiavelli, A. O.; Pardo, R. C.; Richard, A.; Riley, M. A.; Savard, G.; Scheck, M.; Seweryniak, D.; Smith, M. K.; Vondrasek, R.; Wiens, A.

    2016-03-01

    The neutron-rich nucleus 144Ba (t1 /2=11.5 s ) is expected to exhibit some of the strongest octupole correlations among nuclei with mass numbers A less than 200. Until now, indirect evidence for such strong correlations has been inferred from observations such as enhanced E 1 transitions and interleaving positive- and negative-parity levels in the ground-state band. In this experiment, the octupole strength was measured directly by sub-barrier, multistep Coulomb excitation of a post-accelerated 650-MeV 144Ba beam on a 1.0 -mg /cm2 208Pb target. The measured value of the matrix element, ⟨31 -∥M (E 3 )∥01 +⟩=0.65 (+17/-23) e b3 /2, corresponds to a reduced B (E 3 ) transition probability of 48 (+25/-34) W .u . This result represents an unambiguous determination of the octupole collectivity, is larger than any available theoretical prediction, and is consistent with octupole deformation.

  8. Study of the soft dipole modes in 140Ce via inelastic scattering of 17O

    NASA Astrophysics Data System (ADS)

    Krzysiek, M.; Kmiecik, M.; Maj, A.; Bednarczyk, P.; Ciemała, M.; Fornal, B.; Grȩbosz, J.; Mazurek, K.; Mȩczyński, W.; Ziȩbliński, M.; Crespi, F. C. L.; Bracco, A.; Benzoni, G.; Blasi, N.; Boiano, C.; Bottoni, S.; Brambilla, S.; Camera, F.; Giaz, A.; Leoni, S.; Million, B.; Morales, A. I.; Nicolini, R.; Pellegri, L.; Riboldi, S.; Vandone, V.; Wieland, O.; De Angelis, G.; Napoli, D. R.; Valiente-Dobon, J. J.; Bazzacco, D.; Farnea, E.; Gottardo, A.; Lenzi, S.; Lunardi, S.; Mengoni, D.; Michelagnoli, C.; Recchia, F.; Ur, C.; Gadea, A.; Huyuk, T.; Barrientos, D.; Birkenbach, B.; Geibel, K.; Hess, H.; Reiter, P.; Steinbach, T.; Wiens, A.; Bürger, A.; Görgen, A.; Guttormsen, M.; Larsen, A. C.; Siem, S.

    2014-05-01

    The main aim of this study was a deeper understanding of the nuclear structure properties of the soft dipole modes in 140Ce, excited via inelastic scattering of weakly bound 17O projectiles. An important aim was to investigate the ‘splitting’ of the PDR into two parts: a low-energy isoscalar component dominated by neutron-skin oscillations and a higher-energy component lying on the tail of the giant dipole resonance of a rather isovector character. This was already observed for this nucleus, investigated in (α, α‧) and (γ, γ‧) experiments. The experiment was performed at Laboratori Nazionali di Legnaro, Italy. Inelastic scattering of 17O ion beam at 20 MeV A-1 was used to excite the resonance modes in the 140Ce target. Gamma-rays were registered by five triple clusters of AGATA-Demonstrator and nine large volume scintillators (LaBr3). The scattered 17O ions were identified by two ΔE - E Si telescopes of the TRACE array mounted inside the scattering chamber. The telescopes consisted of two segmented Si-pad detectors, each of 60 pixels. Very preliminary data have shown a strong domination of the E1 transitions in the ‘pygmy’ region with a character more similar to the one obtained in alpha scattering experiment.

  9. New Features of Shape Coexistence in {sup 152}Sm

    SciTech Connect

    Garrett, P. E.; Kulp, W. D.; Wood, J. L.; Bandyopadhyay, D.; Choudry, S.; Lesher, S. R.; McEllistrem, M. T.; Mynk, M.; Orce, J. N.; Yates, S. W.; Dashdorj, D.

    2009-08-07

    Excited states in {sup 152}Sm have been investigated with the {sup 152}Sm(n,n{sup '}gamma) reaction. The lowest four negative-parity band structures have been characterized in detail with respect to their absolute decay properties. Specifically, a new K{sup p}i=0{sup -} band has been assigned with its 1{sup -} band head at 1681 keV. This newly observed band has a remarkable similarity in its E1 transition rates for decay to the first excited K{sup p}i=0{sup +} band at 684 keV to the lowest K{sup p}i=0{sup -} band and its decay to the ground-state band. Based on these decay properties, as well as energy considerations, this new band is assigned as a K{sup p}i=0{sup -} octupole excitation based on the K{sup p}i=0{sub 2}{sup +} state. An emerging pattern of repeating excitations built on the 0{sub 2}{sup +} level similar to those built on the ground state may indicate that {sup 152}Sm is a complex example of shape coexistence rather than a critical point nucleus.

  10. NUSTART: A PC code for NUclear STructure And Radiative Transition analysis and supplementation

    SciTech Connect

    Larsen, G.L.; Gardner, D.G.; Gardner, M.A.

    1990-10-01

    NUSTART is a computer program for the IBM PC/At. It is designed for use with the nuclear reaction cross-section code STAPLUS, which is a STAPRE-based CRAY computer code that is being developed at Lawrence Livermore National Laboratory. The NUSTART code was developed to handle large sets of discrete nuclear levels and the multipole transitions among these levels; it operates in three modes. The Data File Error Analysis mode analyzes an existing STAPLUS input file containing the levels and their multipole transition branches for a number of physics and/or typographical errors. The Interactive Data File Generation mode allows the user to create input files of discrete levels and their branching fractions in the format required by STAPLUS, even though the user enters the information in the (different) format used by many people in the nuclear structure field. In the Branching Fractions Calculations mode, the discrete nuclear level set is read, and the multipole transitions among the levels are computed under one of two possible assumptions: (1) the levels have no collective character, or (2) the levels are all rotational band heads. Only E1, M1, and E2 transitions are considered, and the respective strength functions may be constants or, in the case of E1 transitions, the strength function may be energy dependent. The first option is used for nuclei closed shells; the bandhead option may be used to vary the E1, M1, and E2 strengths for interband transitions. K-quantum number selection rules may be invoked if desired. 19 refs.

  11. Transition rates for lithium-like ions, sodium-like ions, and neutral alkali-metal atoms

    SciTech Connect

    Johnson, W.R.; Liu, Z.W.; Sapirstein, J.

    1996-11-01

    Third-order many-body perturbation theory is used to obtain E1 transition amplitudes for ions of the lithium and sodium isoelectronic sequences and for the neutral alkali-metal atoms potassium, rubidium, cesium, and francium. Complete angular reductions of the first, second, and third-order amplitudes are given. Tables of transition energies and rates are given for the 2p{sub {1/2}} {yields} 2s{sub {1/2}}, 2p{sub 3/2} {yields} 2s{sub {1/2}}, 3s{sub {1/2}} {yields} 2p{sub {1/2}}, and 3s{sub {1/2}} {yields} 2p{sub 3/2} transitions in the lithium isoelectronic sequence and for the corresponding 3p{sub 1/2} {yields} 3s{sub 1/2}, 3p{sub 3/2} {yields} 3s{sub {1/2}}, 4s{sub {1/2}} {yields} 3p{sub 1/2}, and 4s{sub {1/2}} {yields} 3p{sub 3/2} transitions in the sodium sequence. For neutral alkali atoms, amplitudes of np{sub {1/2}} {yields} ns{sub {1/2}}, np{sub 3/2} {yields} ns{sub {1/2}}, (n + 1)s{sub {1/2}} {yields} np{sub {1/2}}, and (n + 1)s{sub {1/2}} {yields} np{sub 3/2} transitions are evaluated, where n is the principal quantum number of the valence electron in the atomic ground state, Semi-empirical corrections for the omitted fourth- and higher-order terms in perturbation theory are given for the neutral alkali-metal atoms. Comparisons with previous high-precision calculations and with experiment are made. 42 refs., 1 fig., 12 tabs.

  12. Two-hole structure outside 78Ni: Existence of a μ s isomer of 76Co and β decay into 76Ni

    NASA Astrophysics Data System (ADS)

    Söderström, P.-A.; Nishimura, S.; Xu, Z. Y.; Sieja, K.; Werner, V.; Doornenbal, P.; Lorusso, G.; Browne, F.; Gey, G.; Jung, H. S.; Sumikama, T.; Taprogge, J.; Vajta, Zs.; Watanabe, H.; Wu, J.; Baba, H.; Dombradi, Zs.; Franchoo, S.; Isobe, T.; John, P. R.; Kim, Y.-K.; Kojouharov, I.; Kurz, N.; Kwon, Y. K.; Li, Z.; Matea, I.; Matsui, K.; Martínez-Pinedo, G.; Mengoni, D.; Morfouace, P.; Napoli, D. R.; Niikura, M.; Nishibata, H.; Odahara, A.; Ogawa, K.; Pietralla, N.; Şahin, E.; Sakurai, H.; Schaffner, H.; Sohler, D.; Stefan, I. G.; Suzuki, D.; Taniuchi, R.; Yagi, A.; Yoshinaga, K.

    2015-11-01

    In the EURICA campaign aimed at exploration of the 78Ni region, an isomeric state of 76Co has been observed via γ -ray spectroscopy. The nuclei were produced by in-flight fission of a 238U beam at the Radioactive Isotope-Beam Factory. Two coincident γ rays of 192.02 (30 ) and 446.4 (7 ) keV from the decay of a t1 /2=2.96 (2529) μ s isomeric state of 76Co have been observed. The decay of the isomer was assigned to an E 1 transition with a reduced transition probability of B (E 1 ;3+→2-) =1.79 (16 ) ×10-8 W.u. A β -decaying state with spin-parity 1- and a half-life of 16 (4 ) ms was also observed in the data, and the known state with a half-life of 22 (57) ms was assigned to have a spin-parity of 8-. Furthermore, the isomer of 76Ni has been remeasured to 547.8 (33 ) ns giving a B (E 2 ;8+→6+) value of 0.786 (5 ) W.u. A new excited state at 2994.6 (5 ) keV, decaying via a γ ray of 2004.5(4) keV, has also been observed. This is in agreement with either of the predicted 02+ or 22+ states. These results are discussed in terms of the shell model and the interaction of the ν p1 /2 and π f7 /2 orbitals.

  13. Dipole-Strength Distributions up to the Giant Dipole Resonance Deduced from Photon Scattering

    NASA Astrophysics Data System (ADS)

    Schwengner, R.; Rusev, G.; Benouaret, N.; Beyer, R.; Dönau, F.; Erhard, M.; Grosse, E.; Junghans, A. R.; Kosev, K.; Klug, J.; Nair, C.; Nankov, N.; Schilling, K. D.; Wagner, A.

    2008-04-01

    Dipole-strength distributions up to the neutron-separation energies of the even-mass Mo isotopes from 92Mo to 100Mo and of the N = 50 isotones 88Sr, 89Y, 90Zr have been investigated in photon-scattering experiments using the bremsstrahlung facility at the superconducting electron accelerator ELBE of the Forschungszentrum Dresden-Rossendorf. A measurement using polarised bremsstrahlung impinging on 88Sr revealed that all resolved transitions with energies greater than 6 MeV in this nuclide except for one are E1 transitions. The intensity distributions obtained from the measured spectra after a correction for detector response and a subtraction of atomic background in the target contain a continuum part in addition to the resolved peaks. It turns out that the dipole strength in the resolved peaks amounts to about 30% of the total dipole strength while the continuum contains about 70%. In order to estimate the distribution of inelastic transitions and to correct the ground-state transitions for their branching ratios simulations of γ-ray cascades were performed. The photoabsorption cross sections obtained in this way connect smoothly to (γ, n) cross sections and give novel information about the strength on the low-energy tails of the Giant Dipole Resonances below the neutron-separation energies. The experimental cross sections are compared with predictions of a Quasiparticle-Random-Phase Approximation in a deformed basis. The calculations describe the experimentally observed increase of the dipole strengths with increasing neutron number of the Mo isotopes as a consequence of increasing nuclear deformation.

  14. Quantum size effects on the optical properties of nc-Si QDs embedded in an a-SiOx matrix synthesized by spontaneous plasma processing.

    PubMed

    Das, Debajyoti; Samanta, Arup

    2015-02-21

    Quantum confinement effects on optical transitions in ensembles of nc-Si QDs in an a-SiOx matrix has become evident by simultaneously considering the dielectric function dispersions obtained by optical modeling with spectroscopic ellipsometry, the absorption edge, and the photoluminescence peak. Diminution of the peak amplitude in the ε2-spectra for reducing the diameter of nc-Si QDs could arise due to the disappearance of excitonic effects in the E1 transition, while the peak broadening indicates an amplification of disorder in Si QDs. An energy blue shift happens to take place in an analogous fashion for all the characteristic parameters, upon decreasing the size of the nc-Si QDs for diameters in the range 6.5 < d < 2.0 nm. The band gap widening with the reduction of QD size is well supported by the first-principles calculations based on quantum confinement, while studies on the Stokes shift in the optical gap from the PL data could provide an understanding of the imperfect passivation of the surface defects on tiny nc-Si QDs. Low dimensional nc-Si QDs (∼2 nm in diameter) assembled in a large density (∼2.3 × 10(12) cm(-2)) embedded in an a-SiOx matrix synthesized by spontaneous and low-temperature (300 °C) RF plasma processing, compatible to CMOS technology, are highly conducive for device applications. Systematic changes in composition and characteristics, including the thickness, of the individual sub-layers of the nc-Si QD thin films can be comprehensively pursued through a nondestructive process by ellipsometric simulation which could, thereby, enormously contribute to the precise optimization of the deposition parameters suitable for specific device fabrication e.g., all-silicon tandem solar cells and light emitting diodes, using silicon nanotechnology. PMID:25598473

  15. Study of the neutron and proton capture reactions 10,11B(n, γ), 11B(p, γ), 14C(p, γ), and 15N(p, γ) at thermal and astrophysical energies

    NASA Astrophysics Data System (ADS)

    Dubovichenko, Sergey; Dzhazairov-Kakhramanov, Albert

    2014-07-01

    We have studied the neutron-capture reactions 10,11B(n, γ) and the role of the 11B(n, γ) reaction in seeding r-process nucleosynthesis. The possibility of the description of the available experimental data for cross-sections of the neutron capture reaction on 10B at thermal and astrophysical energies, taking into account the resonance at 475 keV, was considered within the framework of the modified potential cluster model (MPCM) with forbidden states (FS) and accounting for the resonance behavior of the scattering phase shifts. In the framework of the same model, the possibility of describing the available experimental data for the total cross-sections of the neutron radiative capture on 11B at thermal and astrophysical energies were considered with taking into account the 21 and 430 keV resonances. Description of the available experimental data on the total cross-sections and astrophysical S-factor of the radiative proton capture on 11B to the GS of 12C was treated at astrophysical energies. The possibility of description of the experimental data for the astrophysical S-factor of the radiative proton capture on 14C to the GS of 15N at astrophysical energies, and the radiative proton capture on 15N at the energies from 50 to 1500 keV was considered in the framework of the MPCM with the classification of the orbital states according to Young tableaux. It was shown that, on the basis of the M1 and the E1 transitions from different states of the p15N scattering to the GS of 16O in the p15N channel, it is quite succeed to explain general behavior of the S-factor in the considered energy range in the presence of two resonances.

  16. X-ray And EUV Spectroscopy Of Highly Charged Tungsten Ions

    NASA Astrophysics Data System (ADS)

    Biedermann, Christoph; Radtke, Rainer

    2009-09-01

    The Berlin EBIT has been established by the Max-Planck-Institut für Plasmaphysik to generate atomic physics data in support of research in the field of controlled nuclear fusion, by measuring the radiation from highly charged ions in the x-ray, extreme ultraviolet and visible spectral ranges and providing valuable diagnostics for high temperature plasmas [1]. In future fusion devices, for example ITER, currently being constructed at Cadarache, France, the plasma facing components will be armored with high-Z materials, most likely tungsten, due to the favorable properties of this element [2]. At the same time the tremendous radiation cooling of these high-Z materials represents a threat to fusion and obliges one to monitor carefully the radiation. With EBIT a selected ensemble of ions in specific charge states can be produced, stored and excited for spectroscopic investigations. Employing this technique, we have for example resolved the wide structure observed around 5 nm at the ASDEX Upgrade tokamak as originating from E1-transitions into the open 4d shell of tungsten ions in charge states 25+ to 37+ producing a band-like emission pattern [3]. Further, these ions emit well-separated M1 lines in the EUV range around 65 nm suitable for plasma diagnostics [4]. Kr-like to Cr-like tungsten ions (38+ to 50+) show strong soft-x-ray lines in the range 0.5 to 2 and 5 to 15 nm. Lines of even higher charged tungsten ions, up to Ne-like W64+, abundant in the core plasma of present and future fusion test devices, have been investigated with high resolution Bragg-crystal spectroscopy at 0.13 nm [5]. Recently, x-ray spectroscopic measurements of the dielectronic recombination LMn resonances of W60+ to W67+ ions have been preformed and compare well with atomic structure calculations.

  17. Allowed and forbidden transition parameters for Fe XV

    SciTech Connect

    Nahar, Sultana N.

    2009-07-15

    A comprehensive set of fine structure energy levels, oscillator strengths (f), line strengths (S), and radiative decay rates (A) for bound-bound transitions in Fe XV is presented. The allowed electric dipole (E1) transitions were obtained from the relativistic Breit-Pauli R-matrix method which is based on the close coupling approximation. A total of 507 fine structure energy levels with n {<=} 10, l {<=} 9, and 0 {<=} J {<=} 10 are found. They agree within 1% with the available observed energies. These energy levels yield a total of 27,812 E1, same-spin multiplets and intercombination transitions. The A values are in good agreement with those compiled by NIST and other existing values for most transitions. Forbidden transitions are obtained from a set of 20 configurations with orbitals ranging from 1s to 5f using the relativistic code SUPERSTRUCTURE (SS) in the Breit-Pauli approximation. From a set of 123 fine structure levels, a total of 6962 S and A values are presented for forbidden electric quadrupole (E2), electric octupole (E3), magnetic dipole (M1), and magnetic quadrupole (M2) transitions. The energies from SS calculations agree with observed energies to within 1-3%. A values for E2, M1 transitions agree very well with the available values for most transitions while those for M2 transitions show variable agreement. The large set of transition parameters presented should be applicable for both diagnostics and spectral modeling in the X-ray, ultraviolet, and optical regions of astrophysical plasmas.

  18. Resonant X-ray magnetic scattering studies of the TmNi 2B 2C spin density wave

    NASA Astrophysics Data System (ADS)

    Mannix, Danny; Thompson, Paul; Brown, Simon; Bouchenoire, Laurence; Canfield, Paul

    2004-11-01

    We report on polarisation resolved, resonant X-ray magnetic scattering (RXMS) studies of the spin density wave (SDW) formed in the TmNi 2B 2C superconductor. From this high wave-vector resolution investigation, we find the incommensurate magnetic SDW propagation vector to be ( 0±τ0±τ0) with τ=0.096 rlu, slightly larger than the value previously deduced from magnetic neutron studies ( τ=0.093 rlu). The widths of the SDW peaks at 1 K are consistent with long-range magnetic order and we have deduced a magnetic correlation length of ∼1200 Å. When the incident photons are tuned to the Tm L 3 absorption edge, the RXMS energy response consists of a double peak feature, arising from both dipole (E1) transitions, probing the 5d conduction band polarisation, and quadrupole (E2) transitions, probing the Tm 4f magnetic moments. The RXMS wave-vector dependences of the (0± τ 0± τ L) SDW satellites are consistent with the transverse spin-density wave structure, with moments orientated along the crystallographic c-axis, originally proposed from neutron-scattering measurements. Our RXMS data are also in good agreement with the magnetic neutron-scattering response for the thermal evolution of the magnetic moments down to 1 K and in deducing a Nèel temperature of T=1.5 K. However, the RXMS probe reveals a small shift of the magnetic propagation vector of the order 3×10 -3 rlu along the (1 1 0) direction, on decreasing temperature below TN. Using very high-resolution X-ray studies with a conventional Si(1 1 1) analyser, no change in width or position is found below TN or Tc. We have also not observed any charge modulation peaks at 2τ, indicating that the SDW does not couple to the lattice.

  19. High-Resolution {alpha} and Electron Spectroscopy of {sup 249}{sub 98}Cf

    SciTech Connect

    Ahmad, I.; Greene, J. P.; Kondev, F. G.; Zhu, S.

    2015-04-13

    alpha-particle spectra of Cf-249 have been measured with a double-focusing magnetic spectrometer and with passivated implanted planar silicon (PIPS) detectors. The conversion-electron spectra of Cf-249 have been measured with a cooled Si(Li) detector and with a room-temperature PIPS detector. Precise energies of a groups in the decay of Cf-249 have been measured with respect to the known energy of Cf-250. In addition, alpha-electron, alpha-gamma, and gamma-gamma coincidence measurements were also performed to determine the spin-parity of the previously known 643.64-keV level. From electron intensities, conversion coefficients of transitions in the daughter Cm-245 have been determined. The measured L-3 conversion coefficients of the 333.4- and 388.2-keV transitions are found to be in agreement with the theoretical conversion coefficients for pure E1 multipolarity. On the other hand, the K, L-1 + L-2, M, and N conversion coefficients are approximately twice the theoretical values for pure E1 transitions. These measurements indicate anomalous E1 conversion coefficients for the 333.4- and 388.2-keV transitions, as has been pointed out in earlier measurements. The measured conversion coefficient of the 255.5-keV transition gives an M1 multipolarity for this transition which establishes a spin-parity of 7/2(-) and the 7/2(-)[743] single-particle assignment to the 643.64-keV level.

  20. Self-consistent quasiparticle formulation of a multiphonon method and its application to the neutron-rich O20 nucleus

    NASA Astrophysics Data System (ADS)

    De Gregorio, G.; Knapp, F.; Lo Iudice, N.; Vesely, P.

    2016-04-01

    A Bogoliubov quasiparticle formulation of an equation-of-motion phonon method, suited for open-shell nuclei, is derived. Like its particle-hole version, it consists of deriving a set of equations of motions whose iterative solution generates an orthonormal basis of n -phonon states (n =0 ,1 ,2 ,... ), built of quasiparticle Tamm-Dancoff phonons, which simplifies the solution of the eigenvalue problem. The method is applied to the open-shell neutron-rich O20 for illustrative purposes. A Hartree-Fock-Bogoliubov canonical basis, derived from an intrinsic two-body optimized chiral Hamiltonian, is used to derive and solve the eigenvalue equations in a space encompassing a truncated two-phonon basis. The spurious admixtures induced by the violation of the particle number and the center-of-mass motion are eliminated to a large extent by a Gram-Schmidt orthogonalization procedure. The calculation takes into account the Pauli principle, is self-consistent, and is parameter free except for the energy cutoff used to truncate the two-phonon basis, which induces an increasing depression of the ground state through its strong coupling to the quasiparticle vacuum. Such a cutoff is fixed so as to reproduce the first 1- level. The two-phonon states are shown to enhance the level density of the low-energy spectrum, consistently with the data, and to induce a fragmentation of the E 1 strength which, while accounting for the very low E 1 transitions, is not sufficient to reproduce the experimental cross section in the intermediate energy region. This and other discrepancies suggest the need of including the three-phonon states. These are also expected to offset the action of the two phonons on the quasiparticle vacuum and, therefore, free the calculation from any parameter.

  1. Decay of a {pi}h{sub 11/2} x {nu}h{sub 11/2} microsecond isomer in {sub 61}{sup 136}Pm{sub 75}

    SciTech Connect

    Rigby, S. V.; Cullen, D. M.; Mason, P. J. R.; Scholes, D. T.; Scholey, C.; Rahkila, P.; Eeckhaudt, S.; Grahn, T.; Greenlees, P.; Jones, P. M.; Julin, R.; Juutinen, S.; Kettunen, H.; Leino, M.; Leppaenen, A.-P.; Nieminen, P.; Nyman, M.; Pakarinen, J.; Uusitalo, J.

    2008-09-15

    An experiment has been performed to populate several extremely neutron-deficient nuclei around the mass-140 region of the nuclear chart, using a beam of {sup 54}Fe on a {sup 92}Mo target at an energy of 315 MeV. Analysis of these data using recoil-isomer tagging has established that the yrast {pi}h{sub 11/2} x {nu}h{sub 11/2},J{sup {pi}}=(8{sup +}), bandhead state in {sup 136}Pm is isomeric with a half-life of 1.5(1) {mu}s. This isomeric state decays via a 43-keV, probable-E1 transition to a J{sup {pi}}=(7{sup -}) state. Consideration of the theoretical Nilsson orbitals near the Fermi surface suggests that the J{sup {pi}}=(8{sup +}) state has a {nu}h{sub 11/2}[505](11/2){sup -} x {pi}h{sub 11/2}[532](5/2){sup -} configuration, which decays to the J{sup {pi}}=(7{sup -}) state with a {nu}h{sub 11/2}[505](11/2){sup -} x {pi}d{sub 5/2}[411](3/2){sup +} configuration. Differences in the shape-driving effects for these two configurations is reasoned to be responsible for the long half-life of the J{sup {pi}}=(8{sup +}) isomeric state. The non-observation of other {gamma} rays in prompt or delayed coincidence with the 43-keV transition suggests that this transition may feed another, longer lived isomeric state with a half-life of the order of milliseconds or greater. However, the present experiment was not sensitive to the decay of this new J{sup {pi}}=(7{sup -}) state by internal conversion or even {beta} decay.

  2. New isomers and medium-spin structure of the {sup 95}Y nucleus

    SciTech Connect

    Urban, W.; Sieja, K.; Simpson, G. S.; Rzaca-Urban, T.; Zlomaniec, A.; Lukasiewicz, M.; Smith, A. G.; Durell, J. L.; Smith, J. F.; Varley, B. J.; Nowacki, F.; Ahmad, I.

    2009-04-15

    Excited states in {sup 95}Y, populated following the spontaneous fission of {sup 248}Cm and {sup 252}Cf and following fission of {sup 235}U induced by thermal neutrons, were studied by means of {gamma} spectroscopy using the EUROGAM2 and GAMMASPHERE multidetector Ge arrays and the LOHENGRIN fission-fragment separator, respectively. We have found a new (17/2{sup -}) isomer in {sup 95}Y at 3142.2 keV with a half-life of T{sub 1/2}=14.9(5) ns. Another isomer was identified in {sup 95}Y at 5022.1 keV and it was assigned a spin-parity (27/2{sup -}). For this isomer a half-life of T{sub 1/2}=65(4) ns was determined and four decay branches were found, including an E3 decay. A new E3 decay branch was also found for the known, 1087.5-keV isomer in {sup 95}Y, for which we measured a half-life of 51.2(9) {mu}s. The B(E3) and B(E1) transition rates, of 2.0 and 3.8x10{sup -7} W.u., respectively, observed in {sup 95}Y are significantly lower than in the neighboring {sup 96}Zr core, suggesting that octupole correlations in this region are mainly due to the coupling of proton {delta}j=3 orbitals. Shell-model calculations indicate that the (27/2{sup -}) isomer in {sup 95}Y corresponds to the {pi}g{sub 9/2}{nu}(g{sub 7/2}h{sub 11/2}) maximally aligned configuration and that all three isomers in {sup 95}Y decay, primarily, by M2 transitions between proton g{sub 9/2} and f{sub 5/2} orbitals.

  3. High-resolution α and electron spectroscopy of Cf24998

    NASA Astrophysics Data System (ADS)

    Ahmad, I.; Greene, J. P.; Kondev, F. G.; Zhu, S.

    2015-04-01

    α -particle spectra of 249Cf have been measured with a double-focusing magnetic spectrometer and with passivated implanted planar silicon (PIPS) detectors. The conversion-electron spectra of 249Cf have been measured with a cooled Si(Li) detector and with a room-temperature PIPS detector. Precise energies of α groups in the decay of 249Cf have been measured with respect to the known energy of 250Cf. In addition, α -electron, α -γ , and γ -γ coincidence measurements were also performed to determine the spin-parity of the previously known 643.64-keV level. From electron intensities, conversion coefficients of transitions in the daughter 245Cm have been determined. The measured L3 conversion coefficients of the 333.4- and 388.2-keV transitions are found to be in agreement with the theoretical conversion coefficients for pure E 1 multipolarity. On the other hand, the K ,L1+L2 ,M , and N conversion coefficients are approximately twice the theoretical values for pure E 1 transitions. These measurements indicate anomalous E 1 conversion coefficients for the 333.4- and 388.2-keV transitions, as has been pointed out in earlier measurements. The measured conversion coefficient of the 255.5-keV transition gives an M 1 multipolarity for this transition which establishes a spin-parity of 7/2- and the 7/2-[743 ] single-particle assignment to the 643.64-keV level.

  4. The Search for the CP-violating emission of an E1 photon from the K(L) ---> pi+ pi- gamma decay

    SciTech Connect

    Shields, John Michael

    2005-01-01

    A search for the CP-violating electric dipole (E1) direct emission contribution to the K{sub L} {yields} {pi}{sup +}{pi}{sup -}{gamma} decay is performed using data from the 1997 KTeV/E832 experiment. Because the K{sub L} {yields} {pi}{sup +}{pi}{sup -}{gamma} decay mode is massively dominated by the CP-violating inner bremsstrahlung (IB) and the CP-conserving magnetic dipole (M1) direct emission processes, previous analyses have neglected the E1 contribution. Therefore, this measurement is the first attempt to directly quantify the size of the E1 decay process. This E1 transition is one of the very few CP-violating processes that is accessible to experiment and, in principle, will produce new insights into the structure of the neutral kaon. The result of this analysis is that the E1 contribution is below the threshold of sensitivity, and therefore an upper bound of |g{sub E1}| < 0.14 (90% CL) is reported. In the process of obtaining this upper limit, high resolution measurements of fit parameters ({tilde g}{sub M1} and a{sub 1}/a{sub 2}) associated with the size and shape of the M1 direct emission peak are also extracted. The fit results for these parameters: {tilde g}{sub M1} = 1.229 {+-} 0.035 (stat) {+-} 0.087 (syst); a{sub 1}/a{sub 2} = -0.733 {+-} 0.007 (stat) {+-} 0.014 (syst) are in strong agreement with previous measurements.

  5. The (4)He(gamma,dd) reaction at E(gamma) = 150--250 MeV

    NASA Astrophysics Data System (ADS)

    Rice, Bryan Joseph

    1998-09-01

    We have performed a measurement of the cross section for the 4He(/gamma,d)2H reaction with Eγ=150[-]250 MeV at the Saskatchewan Accelerator Laboratory (SAL). The experiment was performed using bremsstrahlung γ rays produced by a 273 MeV electron beam. The target was liquid helium contained in a simple cryostat. Two detector arms consisting of plastic scintillator telescopes were utilized to detect both reaction particles in coincidence. We obtained relative and absolute cross sections at six angles in two energy bins (150-190 and 190-250 MeV). The angular distribution of the cross section shows peaking behavior at 90o in the center-of-mass frame. A Legendre polynomial fit to the data shows this distribution can be described by a sin2/theta angular distribution. This distribution suggests the presence of electric dipole or E1 radiation, but isospin selection rules and identical bosons in the exit channel forbid the dominant /Delta S=0 E1 transition. Performing a transition-matrix element (TME) analysis using only strictly allowed transitions, we found that the observed angular distribution could be described by the constructive interference of just two TME's: electric quadrupole (E2) s- and d-wave capture to the D-state of 4He. We performed a direct-capture calculation in order to determine if the D-state could contribute to such a high degree to the cross section. Our calculations, which used an optical model potential from elastic scattering data at lower energies, yielded the result that 90% of the cross section arises from capture to the D-state. The calculation, however, places all capture strength to the D-state into g-wave capture and, as a result, fails to reproduce the observed sin2/theta angular distribution. The lack of existing theoretical work for this system at these energies conspires to keep the mechanism for this angular distribution unclear, but we hope this result will motivate four-body theorists to extend their calculations to this energy

  6. Theoretical study on the low-lying excited states of the phosphorus monoiodide (PI) including the spin-orbit coupling

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaomei; Liu, Xiaoting; Liang, Guiying; Li, Rui; Xu, Haifeng; Yan, Bing

    2016-01-01

    The potential energy curves (PECs) of the 22 Λ-S states of the phosphorus monoiodide (PI) molecule have been calculated at the level of MRCI+Q method with correlation-consistent quadruple-ζ quality basis set. The spectroscopic constants of the bound states are determined, which well reproduce the available measurements. The metastable a1Δ state has been reported for the first time, which lies between the X3Σ- and b1Σ+ states and have much deeper well than the ground state. The R-dependent spin-orbit (SO) matrix elements are calculated with the full-electron Breit-Pauli operator. Based on the SO matrix elements, the perturbations that the 23Π state may suffer from are analyzed in detail. The SOC effect makes the original Λ-S states split into 51 Ω states. In the zero-field splitting of the ground state X3Σ-, the spin-spin coupling contribution (2.23 cm-1) is found to be much smaller compared to the spin-orbit coupling contribution (50 cm-1). The avoided crossings between the Ω states lead to much shallower potential wells and the change of dissociation relationships of the states. The Ω-state wavefunctions are analyzed depending on their Λ-S compositions, showing the strong interactions among several quasidegenerate Λ-S states of the same total SO symmetry. The transition properties including electric dipole (E1), magnetic dipole (M1), and electric quadrupole (E2) transition moments (TMs), the Franck-Condon factors, the transition probabilities and the radiative lifetimes are computed for the transitions between Ω components of a1Δ and b1Σ+ states and ground state. The transition probabilities induced by the E1, E2, and M1 transitions are evaluated. The E2 makes little effect on transition probabilities. In contrast, the E1 transition makes the main contribution to the transition probability and the M1 transition also brings the influence that cannot be neglected. Finally, the radiative lifetimes are determined with the transition moments including E

  7. Pre-steady-state kinetic study of the effects of K+ on the partial reactions of the catalytic cycle of the plasma membrane Ca(2+)-ATPase.

    PubMed Central

    Herscher, C J; Rega, A F; Adamo, H P

    1996-01-01

    The effects of 100 mM K+ on the partial reactions that take place during ATP hydrolysis on the calcium ion-dependent ATPase from plasma membrane (PM-Ca(2+)-ATPase) were studied at 37 degrees C on fragmented intact membranes from pig red cells by means of a rapid chemical quenching technique. At 10 microM [gamma-32P]ATP plus non-limiting concentrations of Ca2+ and Mg2+, K+ increased the k(app) of formation by 140% to 84 11 s-1 and the steady-state level of phosphoenzyme (EP) by 25% to 3.4 0.17 pmol/mg of protein. If added together with [gamma-32P]ATP at the beginning of phosphorylation, K+ was much less effective than if added earlier, indicating that it did not act on the phosphorylation reaction. Measurements of the E2 --> E1 transition by phosphorylation showed that in medium with Ca2+ and Mg2+, K+ increased the k(app) of the transition by 55% to 14 3 s-1 and the apparent concentration of E1 by 45%, suggesting that this may be the cause of the increased rate of phosphorylation observed in enzyme preincubated with K+. The presence of K+ did not change the slow decay of EP without Mg2+ but activated the decay of EP made with Mg2+, increasing its k(app) by 60% to 91 12 s-1. In contrast with observations made during phosphorylation, if added at the beginning of dephosphorylation K+ was fully effective in favouring decomposition of EP made in medium containing no K+. In the presence of either 3mM ATP or 3 mM ATP plus calmodulin, which activate hydrolysis of CaE2P, the effect of K+ on dephosphorylation was conserved. Because the sites for K+ are intracellular and the concentration of K+ in normal red cells is above 100 mM, the effects described here must be taken into account to describe the catalytic cycle of the PM-Ca(2+)-ATPase under physiological conditions. PMID:8615846

  8. Nuclear structure studies close to N = Z = 50

    NASA Astrophysics Data System (ADS)

    Kumar, S.; Sihotra, S.; Naik, Z.; Singh, K.; Goswami, J.; Singh, N.; Palit, R.; Muralithar, S.; Kumar, R.; Singh, R. P.; Bhowmik, R. K.; Mehta, D.

    2014-08-01

    The level structures in 98,99Rh, and 99Pd nuclei have been investigated through in beam γ-ray spectroscopic techniques following the 75As(overflow="scroll">28Si, xpyn) fusion-evaporation reaction at Elab = 120 MeV. These investigations were carried out using Indian-National-Gamma-Array (INGA) consisting of Compton-suppressed clover detectors at the Inter-University Accelerator Centre, New Delhi. The level structures observed in 99Pd, and 98,99Rh have been established up to ˜ 11 MeV, 10 MeV and 16 MeV excitation energy and spin ˜ 23ħ, 23ħ, and 28ħ respectively. In the doubly-odd 98Rh nucleus, new band structures and isomeric states have been identified at lower spins and new states below the previously identified 2+ ground state (T1/2 = 8.5 m) are identified. In the present work 99Rh structure have been observed similar to 101Rh which is based on p1/2 and g9/2 orbitals. Various positive and negative parity states in these nuclei are observed to be energetically more favored with respect to the neighboring ones, and are likely to be the maximally aligned states obtained by angular momentum coupling of the valence particles (holes). The level structures observed in 99Pd have been interpreted in the framework of a microscopic theory based on the deformed Hartree-Fock (HF) and angular momentum projection techniques. Band structures at low excitation energy are based on the low-Ω νg7/2 and νd5/2 orbitals, have been observed in 99Pd. Band structure at higher spins are reproduced with the ν(g7/2)2⊗ν(g9/2)-1⊗ν(h11/2)2⊗π(g9/2)6 configurations. Observation of new E1 transitions linking the opposite parity νh11/2 and νd5/2 bands provide fingerprints of possible octupole correlations in 99Pd. The extracted values of the B(E1)/B(E2) ratios for the lower levels in the νh11/2 band are ˜ 10-7 [fm]-2.

  9. Relativistic many-body calculations of electric-dipole lifetimes, rates, and oscillator strengths of Delta(n) = 0 transitions between 3l^-1 4l' states in Ni-like ions

    SciTech Connect

    Safronova, U I; Safronova, A S; Beiersdorfer, P

    2007-01-05

    Transition rates, oscillator strengths, and line strengths are calculated for electric-dipole (E1) transitions between odd-parity 3s{sup 2}3p{sup 6}3d{sup 9}4{ell}{sub 2}, 3s{sup 2}3p{sup 5}3d{sup 10}4{ell}{sub 2}, and 3s3p{sup 6}3d{sup 10}4{ell}{sub 1} states and even-parity 3s{sup 2}3p{sup 6}3d{sup 9}4{ell}{sub 2}, 3s{sup 2}3p{sup 5}3d{sup 10}4{ell}{sub 1}, and 3s3p{sup 6}3d{sup 10}4{ell}{sub 2} (with 4{ell}{sub 1} = 4p; 4f and 4{ell}{sub 2} = 4s; 4d) in Ni-like ions with the nuclear charges ranging from Z = 34 to 100. Relativistic many-body perturbation theory (RMBPT), including the Breit interaction, is used to evaluate retarded E1 matrix elements in length and velocity forms. The calculations start from a 1s{sup 2}2s{sup 2}2p{sup 6}3s{sup 2}3p{sup 6}3d{sup 10} Dirac-Fock potential. First-order RMBPT is used to obtain intermediate coupling coefficients and second-order RMBPT is used to calculate transition matrix elements. Contributions from negative-energy states are included in the second-order E1 matrix elements to ensure the gauge independence of transition amplitudes. Transition energies used in the calculation of oscillator strengths and transition rates are from second-order RMBPT. Lifetimes of the 3s{sup 2}3p{sup 6}3d{sup 9}4d levels are given for Z = 34-100. Transition rates, line strengths, and oscillator strengths are compared with critically evaluated experimental values and with results from other recent calculations. These atomic data are important in modeling of M-shell radiation spectra of heavy ions generated in electron beam ion trap experiments and in M-shell diagnostics of plasmas.

  10. Nuclear structure studies close to N = Z = 50

    SciTech Connect

    Kumar, S.; Sihotra, S.; Singh, K.; Goswami, J.; Singh, N.; Mehta, D.; Naik, Z.; Palit, R.; Muralithar, S.; Kumar, R.; Singh, R. P.; Bhowmik, R. K.

    2014-08-14

    The level structures in {sup 98,99}Rh, and {sup 99}Pd nuclei have been investigated through in beam γ-ray spectroscopic techniques following the {sup 75}As({sup 28}Si, xpyn) fusion-evaporation reaction at E{sub lab} = 120 MeV. These investigations were carried out using Indian-National-Gamma-Array (INGA) consisting of Compton-suppressed clover detectors at the Inter-University Accelerator Centre, New Delhi. The level structures observed in {sup 99}Pd, and {sup 98,99}Rh have been established up to ∼ 11 MeV, 10 MeV and 16 MeV excitation energy and spin ∼ 23ħ, 23ħ, and 28ħ respectively. In the doubly-odd {sup 98}Rh nucleus, new band structures and isomeric states have been identified at lower spins and new states below the previously identified 2{sup +} ground state (T{sub 1/2} = 8.5 m) are identified. In the present work {sup 99}Rh structure have been observed similar to {sup 101}Rh which is based on p{sub 1/2} and g{sub 9/2} orbitals. Various positive and negative parity states in these nuclei are observed to be energetically more favored with respect to the neighboring ones, and are likely to be the maximally aligned states obtained by angular momentum coupling of the valence particles (holes). The level structures observed in {sup 99}Pd have been interpreted in the framework of a microscopic theory based on the deformed Hartree-Fock (HF) and angular momentum projection techniques. Band structures at low excitation energy are based on the low-Ω νg{sub 7/2} and νd{sub 5/2} orbitals, have been observed in {sup 99}Pd. Band structure at higher spins are reproduced with the ν(g{sub 7/2}){sup 2}⊗ν(g{sub 9/2}){sup −1}⊗ν(h{sub 11/2}){sup 2}⊗π(g{sub 9/2}){sup 6} configurations. Observation of new E1 transitions linking the opposite parity νh{sub 11/2} and νd{sub 5/2} bands provide fingerprints of possible octupole correlations in {sup 99}Pd. The extracted values of the B(E1)/B(E2) ratios for the lower levels in the νh{sub 11/2} band are ∼ 10{sup

  11. A Two-Photon E1-M1 Optical Clock

    NASA Astrophysics Data System (ADS)

    Alden, Emily A.

    Innovations in precision frequency measurement advance popular technologies such as global positioning systems (GPS), permit the testing of fundamental physics constants, and have the potential to measure local variations in gravity. Driving optical transitions for frequency measurement using an E1-M1 excitation scheme in a hot mercury (Hg) vapor cell is viable and could be the basis of a portable optical frequency standard with comparable accuracy to the most precise atomic clocks in the world. This dissertation explores the fundamental physics of the new E1-M1 method of high-precision frequency measurement in an optical, atomic clock and describes the construction of a high-power E1-M1 clock laser. The value of this new scheme compared to existing optical frequency standards is the simplicity and portability of the experimental setup. Such an optical frequency standard would permit frequency measurement in far-flung locations on earth and in space. Analysis of both the E1-M1 optical transition and thermal properties of the candidate clock atoms are presented. These models allow a stability estimate of an E1-M1 optical clock and recommend experimental settings to optimize the standard. The experimental work that has been performed in pursuit of observing the E1-M1 clock transition in Hg is also discussed. An optical clock operates by making a precision frequency measurement of a laser that has been brought into resonance with a clock atom's oscillator: a high quality atomic level transition. Group II type atoms, such as Hg, have the 1S0-3P0 transition that is an ideal basis for a clock. The E1-M1 excitation is performed by driving the two-photon allowed transition 1S0-3P1-3P0. This is in contrast to the single-photon E1 transition used in other systems. Single-photon schemes must use ultracold atoms to reduce atomic motion to attain high levels of accuracy. Driving the clock transition with a pair of degenerate counter-propagating photons in an E1-M1 scheme

  12. Information Content of the Low-Energy Electric Dipole Strength: Correlation Analysis

    SciTech Connect

    Reinhard, P.-G.; Nazarewicz, Witold

    2013-01-01

    Background: Recent experiments on the electric dipole (E1) polarizability in heavy nuclei have stimulated theoretical interest in the low-energy electric dipole strength, both isovector and isoscalar. Purpose: We study the information content carried by the electric dipole strength with respect to isovector and isoscalar indicators characterizing bulk nuclear matter and finite nuclei. To separate isoscalar and isovector modes, and low-energy strength and giant resonances, we analyze the E1 strength as a function of the excitation energy E and momentum transfer q. Methods: We use the self-consistent nuclear density functional theory with Skyrme energy density functionals, augmented by the random phase approximation, to compute the E1 strength and covariance analysis to assess correlations between observables. Calculations are performed for the spherical, doubly magic nuclei 208Pb and 132Sn. Results: We demonstrate that E1 transition densities in the low-energy region below the giant dipole resonance exhibit appreciable state dependence and multinodal structures, which are fingerprints of weak collectivity. The correlation between the accumulated low-energy strength and the symmetry energy is weak, and dramatically depends on the energy cutoff assumed. On the other hand, a strong correlation is predicted between isovector indicators and the accumulated isovector strength at E around 20 MeV and momentum transfer q 0.65 fm 1. Conclusions: Momentum- and coordinate-space patterns of the low-energy dipole modes indicate a strong fragmentation into individual particle-hole excitations. The global measure of low-energy dipole strength correlates poorly with the nuclear symmetry energy and other isovector characteristics. Consequently, our results do not support the suggestion that there exists a collective pygmy dipole resonance, which is a strong indicator of nuclear isovector properties. By considering nonzero values of momentum transfer, one can isolate individual

  13. The Spectroscopic Evolution of the Symbiotic-like Recurrent Nova V407 Cygni During Its 2010 Outburst. 2. The Circumstellar Environment and the Aftermath

    NASA Technical Reports Server (NTRS)

    Shore, S. N.; Wahlgren, G. M.; Augusteijn, T.; Liimets, T.; Koubsky, P.; Slechta, M.; Votruba, V.

    2011-01-01

    contributor, and the lower states are collisionally quenched but emit from the low density surroundings. Absorption lines of Fe-peak ions formed in the Mira wind were visible as P Cyg profiles at low velocity before Day 69, around the time of the X-ray peak and we identified many absorption transitions without accompanying emission for metal lines. The H Balmer lines showed strong P Cyg absorption troughs that weakened during the 2010 observing period, through Day 128. The Fe-peak line profiles and flux variations were different for permitted and forbidden transitions: the E1 transitions were not visible after Day 128 but had shown a narrow peak superimposed on an extended (200 km/s) blue wing, while the M1 and E2 transitions persisted to Day 529, the last observation, and showed extended redshifted wings up of the same velocity. We distinguish the components from the shock, the photoionized environment, and the chromosphere and inner Mira wind using spectra taken more than one year after outburst. The multiple shells and radiative excitation phenomenology are similar to those recently cited for GRBs and SNIa .