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  • 151.
    Qi, Chong
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Energy expressions for n=3 and 4 systems in a single-j shell2010In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 81, no 3, p. 034318-Article in journal (Refereed)
    Abstract [en]

    For systems with three and four fermions within a single-j shell, analytical expressions for the state energies are presented from a decomposition of the angular momentum. In some important cases the expressions acquire a very simple form. The expression may help us in understanding the structure of isomeric states. The decomposition also makes it possible to construct the algebraic condition for conservation of seniority.

  • 152.
    Qi, Chong
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Partial conservation of seniority in the j=9/2 shell: Analytic and numerical studies2011In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 83, no 1, p. 014307-Article in journal (Refereed)
    Abstract [en]

    Recent studies show that for systems with four identical fermions in the j = 9/2 shell, two special states, which have seniority v = 4 and total spins I = 4 and 6, are eigenstates of any two-body interaction. These states have good seniority for an arbitrary interaction. In this work, an analytic proof is given to this peculiar occurrence of partial conservation of seniority, which is the consequence of the special property of certain coefficients of fractional parentage. Further calculations did not reveal its existence in systems with other n and/or I for shells with j <= 15/2.

  • 153.
    Qi, Chong
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Andreyev, A. N.
    Huyse, M.
    Liotta, Roberto
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Van Duppen, P.
    Wyss, Ramon A.
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Abrupt changes in alpha-decay systematics as a manifestation of collective nuclear modes2010In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 81, no 6, p. 064319-Article in journal (Refereed)
    Abstract [en]

    An abrupt change in alpha-decay systematics around the N = 126 neutron shell closure is discussed. It is explained as a sudden hindrance of the clustering of the nucleons that eventually form the a particle. This is because the clustering induced by the pairing mode acting upon the four nucleons is inhibited if the configuration space does not allow a proper manifestation of the pairing collectivity.

  • 154.
    Qi, Chong
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Blomqvist, Jan
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Bäck, Torbjörn
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Cederwall, Bo
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Johnson, Arne
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Liotta, Roberto
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Wyss, Ramon
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Spin-aligned neutron-proton pair mode in atomic nuclei2011In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 84, no 2, p. 021301-Article in journal (Refereed)
    Abstract [en]

    Shell-model calculations using realistic interactions reveal that the ground and low-lying yrast states of the N = Z nucleus (92)(46)Pd are mainly built upon isoscalar neutron-proton pairs, each carrying the maximum angular momentum J = 9 allowed by the shell 0g(9/2), which is dominant in this nuclear region. This structure is different from that found in the ground and low-lying yrast states of all other even-even nuclei studied so far. The low-lying spectrum of excited states generated by such correlated neutron-proton pairs has two distinctive features: (i) the levels are almost equidistant at low energies and (ii) the transition probability I -> I - 2 is approximately constant and strongly selective. This unique mode is shown to replace normal isovector pairing as the dominant coupling scheme in N = Z nuclei approaching the doubly magic nucleus (100)Sn.

  • 155.
    Qi, Chong
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Chen, T.
    Exact solution of the pairing problem for spherical and deformed systems2015In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 92, no 5Article in journal (Refereed)
    Abstract [en]

    There has been increasing interest in studying the Richardson model from which one can derive the exact solution for certain pairing Hamiltonians. However, it is still a numerical challenge to solve the nonlinear equations involved. In this paper we tackle this problem by employing a simple hybrid polynomial approach. The method is found to be robust and is valid for both deformed and nearly spherical nuclei. It also provides important and convenient initial guesses for spherical systems with large degeneracy. As an example, we apply the method to study the shape coexistence in neutron-rich Ni isotopes.

  • 156.
    Qi, Chong
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Delion, Doru S.
    Liotta, Roberto J.
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Wyss, Ramon
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Effects of formation properties in one-proton radioactivity2012In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 85, no 1, p. 011303-Article in journal (Refereed)
    Abstract [en]

    It is shown that the proton formation probability, extracted from experimental data corresponding to one-proton radioactivity, is divided into two regions when plotted as a function of an universal parameter. This parameter is derived from a microscopic description of the decay process. In this way we explain the systematics of proton emission half-lives. At the same time the formation probability is shown to be a useful quantity to determine the deformation property of the mother nucleus.

  • 157.
    Qi, Chong
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Wang, X. B.
    Xu, Zhen Xiang
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Liotta, Roberto
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Wyss, Ramon
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Xu, F. R.
    Alternate proof of the Rowe-Rosensteel proposition and seniority conservation2010In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 82, no 1, p. 014304-Article in journal (Refereed)
    Abstract [en]

    For a system with three identical nucleons in a single-j shell, the states can be written as the angular-momentum coupling of a nucleon pair and the odd nucleon. The overlaps between these nonorthonormal states form a matrix that coincides with the one derived by Rowe and Rosensteel [Phys. Rev. Lett. 87, 172501 ( 2001)]. The propositions they state are related to the eigenvalue problems of the matrix and dimensions of the associated subspaces. In this work, the propositions are proven from the symmetric properties of the 6j symbols. Algebraic expressions for the dimension of the states, eigenenergies, as well as conditions for conservation of seniority can be derived from the matrix.

  • 158.
    Qi, Chong
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Xu, F. R.
    Liotta, Roberto J.
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Wyss, Ramon
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Zhang, M. Y.
    Asawatangtrakuldee, C.
    Hu, D.
    Microscopic mechanism of charged-particle radioactivity and generalization of the Geiger-Nuttall law2009In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 80, no 4, p. 044326-Article in journal (Refereed)
    Abstract [en]

    A linear relation for charged-particle emissions is presented starting from the microscopic mechanism of the radioactive decay. It relates the logarithms of the decay half-lives with two variables, called. chi' and. rho', which depend upon the Q values of the outgoing clusters as well as the masses and charges of the nuclei involved in the decay. This relation explains well all known cluster decays. It is found to be a generalization of the Geiger-Nuttall law in a radioactivity, and therefore we call it the universal decay law. Predictions of the most likely emissions of various clusters are presented by applying the law over the whole nuclear chart. It is seen that the decays of heavier clusters with nonequal proton and neutron numbers are mostly located in the trans-lead region. The emissions of clusters with equal protons and neutrons, like C-12 and O-16, are possible in some neutron-deficient nuclei with Z >= 54.

  • 159.
    Qi, Chong
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Xu, Zhenxiang
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Monopole-optimized effective interaction for tin isotopes2012In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 86, no 4, p. 044323-Article in journal (Refereed)
    Abstract [en]

    We present a systematic configuration-interaction shell-model calculation on the structure of light tin isotopeswith a global optimized effective interaction. The starting point of the calculation is the realistic CD-Bonnnucleon-nucleon potential. The unknown single-particle energies of the 1d3/2, 2s1/2, and 0h11/2 orbitals and theT = 1 monopole interactions are determined by fitting to the binding energies of 157 low-lying yrast states in102−132Sn. We apply the Hamiltonian to analyze the origin of the spin inversion between 101Sn and 103Sn that wasobserved recently and to explore the possible contribution from interaction terms beyond the normal pairing.

  • 160. Radulov, D.
    et al.
    Chiara, C. J.
    Darby, I. G.
    De Witte, H.
    Diriken, J.
    Fedorov, D. V.
    Fedosseev, V. N.
    Fraile, L. M.
    Huyse, M.
    Koester, U.
    Marsh, B. A.
    Pauwels, D.
    Popescu, L.
    Seliverstov, M. D.
    Sjödin, A. Marica
    KTH, School of Engineering Sciences (SCI), Physics.
    Van den Bergh, P.
    Van Duppen, P.
    Venhart, M.
    Walters, W. B.
    Wimmer, K.
    beta decay of Mn-61 to levels in Fe-612013In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 88, no 1, p. 014307-Article in journal (Refereed)
    Abstract [en]

    A detailed beta-decay study of Mn-61 is presented, yielding extended information on the level structure of Fe-61. Pure beams were obtained at ISOLDE, CERN, after selective laser ionization and mass separation of fission products from the bombardment of a UCx target by 1.4-GeV protons. The beta and gamma information was detected by two MiniBall clusters and three Delta E plastic scintillators. The new Mn-61 decay scheme reveals 48 gamma transitions, distributed over 20 excited states. A comparison to the decay scheme of Mn-59 and excited states in Fe-59 is made. Shell-model calculations with two different interactions are performed in order to compare the nuclear structure of the two neighboring odd-A iron isotopes. Tentative spin and parities of several excited states in Fe-61 are assigned on the basis of beta-decay feeding patterns in both Fe-59,Fe-61 and of results from the theoretical shell-model calculations.

  • 161. Robin, J.
    et al.
    Byrski, T.
    Duchene, G.
    Beck, F. A.
    Cederwall, Bo
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Lagergren, K.
    et al,
    Extended investigation of superdeformed bands in Tb-151,Tb-152 nuclei2008In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 77, no 1Article in journal (Refereed)
    Abstract [en]

    A detailed study of known and new SD bands in Tb isotopes has been performed with the use of the EUROBALL IV gamma-ray array. The high-statistics data set has allowed for the extension of known SD bands at low and high spins by new gamma-ray transitions. These transitions, as it turns out, correspond to the rotational frequencies where the principal superdeformed gaps (Z=66,N=86) close giving rise to up- or down-bending mechanisms. This enables to attribute the underlying theoretical configurations with much higher confidence as compared to the previous identifications. Five new SD bands have been discovered, three of them assigned to the Tb-152 and the two others to the Tb-151 nuclei. Nuclear mean-field calculations have been used to interpret the structure of known SD bands as well as of the new ones in terms of nucleonic configurations.

  • 162. Robin, J.
    et al.
    Odahara, A.
    Duchene, G.
    Beck, F. A.
    Twin, P.
    Cederwall, Bo
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Lagergren, K.
    Lo Bianco, G.
    et al,
    Discrete decay of the yrast superdeformed band in the Tb-151 nucleus2008In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 78, no 3Article in journal (Refereed)
    Abstract [en]

    The Euroball array has been used to search for linking transitions between the superdeformed (SD) and the normal deformed (ND) wells in Tb-151. Many. rays in the energy range 2-4 MeV have been observed in coincidence with the yrast SD band. It is proposed that the highest energy transition of 3748 keV and the strongest line (2818 keV) of the previously observed transitions both decay from the same SD level as their links with the ND states have been identified. The current spectra have insufficient statistics to completely identify the decay point in the SD band. Theoretical calculations covering SD bands in the A approximate to 150 region enable the two possible spin assignments to be compared with experimental data on proposed links in Gd-149 and Dy-152. It is concluded that the energy of the lowest SD band member in Tb-151 has an excitation energy of 12861 keV and a spin of 65/2(+).

  • 163. Roux, D. G.
    et al.
    Gueorguieva, E.
    Babu, B. R. S.
    Aschman, D. G.
    Benatar, M.
    Fearick, R.
    Fetea, M. S.
    Lawrie, J. J.
    Mabala, G. K.
    Mullins, S. M.
    Murray, S. T. H.
    Naguleswaran, S.
    Newman, R. T.
    Rigollet, C.
    Sharpey-Schafer, J. F.
    Smit, F. D.
    Whittaker, W. J.
    Wyss, Ramon A.
    Signature inversion in the yrast band of Ta-1642002In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 65, no 1Article in journal (Refereed)
    Abstract [en]

    Excited states in Ta-164 were populated in the Nd-142(Al-27,5n)Ta-164 reaction and investigated using the AFRODITE spectrometer Arran. The yrast rotational decay sequence Lip to spin 21(-) is identified for the first time and assigned to the pi[514]9/2(-) x nu[660]1/2(+) configuration. A less intense. excited hand is also identified. Low-spin signature inversion is observed in the yrast band, and is compared with the extended total Routhian surface calculations. It is likely that quadrupole pairing plays a role in generating the anomalous signature splitting, but an additional mechanism apart front the assumed mean field and quadrupole pairing interaction may be required to account for the experimental data.

  • 164. Ruchowska, E.
    et al.
    Plociennik, W. A.
    Zylicz, A.
    Mach, H.
    Kvasil, J.
    Algora, A.
    Amzal, N.
    Bäck, Torbjörn
    KTH, School of Engineering Sciences (SCI), Physics.
    Borge, M. G.
    Boutami, R.
    Butler, P. A.
    Cederkäll, J.
    Cederwall, Bo
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Fogelberg, B.
    Fraile, L. M.
    Fynbo, H. O. U.
    Hagebo, E.
    Hoff, P.
    Gausemel, H.
    Jungclaus, A.
    Kaczarowski, R.
    Kerek, Andras
    KTH, School of Technology and Health (STH), Medical Engineering.
    Kurcewicz, W.
    Lagergren, K.
    KTH, School of Engineering Sciences (SCI), Physics.
    Nacher, E.
    Rubio, B.
    Syntfeld, A.
    Tengblad, O.
    Wasilewski, A. A.
    Weissman, L.
    Nuclear structure of Th-2292006In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 73, no 4Article in journal (Refereed)
    Abstract [en]

    Lifetimes of excited states in Th-229, populated in the beta decay of Ac-229, have been measured using the advanced time-delayed beta gamma gamma(t) method. Half-lives of 14 states have been determined including 11 of them for the first time. Twenty-seven new gamma lines have been introduced into the beta-decay scheme of Ac-229 based on results of gamma gamma coincidence measurements. Reduced transition probabilities have been determined for more than 70 gamma transitions in Th-229. Average parallel to D-0 parallel to values of 0.029(1), 0.077(3), and 0.024(5) e fm have been deduced for the lowest K-pi=1/2(+/-),3/2(+/-), and 5/2(+/-) parity partner bands, respectively. Excited states in Th-229 and experimental transition rates have been interpreted within the quasiparticle-plus-phonon model. The half-life of the 3.5-eV, 3/2(+) isomeric state is predicted to be about 10 h. Potential energy surfaces on the (beta(2),beta(3)) plane for the lowest single quasiparticle configurations in Th-229 have been calculated using the Strutinsky method.

  • 165. Sahin, E.
    et al.
    Doncel, Maria
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics. University of Salamanca, Spain.
    Sieja, K.
    de Angelis, G.
    Gadea, A.
    Quintana, B.
    Gorgen, A.
    Modamio, V.
    Mengoni, D.
    Valiente-Dobon, J. J.
    John, P. R.
    Albers, M.
    Bazzacco, D.
    Benzoni, G.
    Birkenbach, B.
    Cederwall, Bo
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Clement, E.
    Curien, D.
    Corradi, L.
    Desesquelles, P.
    Dewald, A.
    Didierjean, F.
    Duchene, G.
    Eberth, J.
    Erduran, M. N.
    Farnea, E.
    Fioretto, E.
    de France, G.
    Fransen, C.
    Gernhaeuser, R.
    Gottardo, A.
    Hackstein, M.
    Hagen, T.
    Hernandez-Prieto, A.
    Hess, H.
    Hueyuek, T.
    Jungclaus, A.
    Klupp, S.
    Korten, W.
    Kusoglu, A.
    Lenzi, S. M.
    Ljungvall, J.
    Louchart, C.
    Lunardi, S.
    Menegazzo, R.
    Michelagnoli, C.
    Mijatovic, T.
    Million, B.
    Molini, P.
    Montagnoli, G.
    Montanari, D.
    Moeller, O.
    Napoli, D. R.
    Obertelli, A.
    Orlandi, R.
    Pollarolo, G.
    Pullia, A.
    Recchia, F.
    Reiter, P.
    Rosso, D.
    Rother, W.
    Salsac, M. -D
    Scarlassara, F.
    Schlarb, M.
    Siem, S.
    Singh, Pushpendra P.
    Soderstrom, P. -A
    Stefanini, A. M.
    Stezowski, O.
    Sulignano, B.
    Szilner, S.
    Theisen, Ch
    Ur, C. A.
    Yalcinkaya, M.
    Shell evolution beyond N=40: Cu-69,Cu-71,Cu-732015In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 91, no 3, article id 034302Article in journal (Refereed)
    Abstract [en]

    The level structure of the neutron-rich Cu-69, Cu-71, and Cu-73 isotopes has been investigated by means of multinucleon transfer reactions. The experiment was performed at Laboratori Nazionali di Legnaro using the AGATA Demonstrator array coupled to the PRISMA magnetic spectrometer. Lifetimes of excited states in Cu nuclei were measured with the recoil-distance Doppler-shift method. The resulting electromagnetic matrix elements for transitions from excited states in Cu-69,Cu-71,Cu-73 nuclei are used to assess the collective or single-particle character of these states. The results are compared with predictions of large-scale shell-model calculations, giving further insight into the evolution of the proton pf shell as neutrons fill the 1g(9/2) orbital.

  • 166.
    Sandulescu, Neculai
    KTH, Superseded Departments, Physics.
    Nuclear superfluidity and specific heat in the inner crust of neutron stars2004In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 70, no 2, p. 025801-Article in journal (Refereed)
    Abstract [en]

    We analyze the temperature dependence of pairing correlations in the inner crust matter of neutron stars. The study is done in a finite-temperature HFB approach and by using a zero range pairing force adjusted to the pairing properties of infinite neutron matter. Within the same approach we investigate how the specific heat of the inner crust depends on temperature, matter inhomogeneity, and the assumption used for the pairing force. It is shown that in a physical relevant range of densities the pairing properties of inner crust matter depend significantly on temperature. The finite-temperature HFB calculations show also that the specific heat is rather sensitive to the presence of nuclear clusters inside the inner crust. However, the most dramatic change of the specific heat is determined by the scenario used for the neutron matter superfluidity.

  • 167.
    Sandulescu, Neculai
    et al.
    KTH, Superseded Departments, Physics.
    Van Giai, N
    Liotta, Roberto
    KTH, Superseded Departments, Physics.
    Superfluid properties of the inner crust of neutron stars2004In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 69, no 4, p. 045802-Article in journal (Refereed)
    Abstract [en]

    Superfluid properties of the inner crust matter of neutron stars, formed by nuclear clusters immersed in a dilute neutron gas, are analyzed in a self-consistent Hartree-Fock-Bogoliubov approach. The calculations are performed with two pairing forces, fixed so as to obtain in infinite nuclear matter the pairing gaps provided by the Gogny force or by induced interactions. It is shown that the nuclear clusters can either suppress or enhance the pairing correlations inside the inner crust matter, depending on the density of the surrounding neutrons. The profile of the pairing field in the inner crust is rather similar for both pairing forces, but the values of the pairing gaps are drastically reduced for the force which simulates the polarization effects in infinite neutron matter.

  • 168.
    Sandzelius, Mikael
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Cedervall, Bo
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Ganioglu, Ela
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Bäck, Torbjörn
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Johnson, Arne
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Andgren, Karin
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Wyss, Ramon
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Hadinia, Baharak
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Khaplanov, Anton
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    (gamma)-ray spectroscopy of 163Ta2009In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 80, no 5, p. 054316-Article in journal (Refereed)
    Abstract [en]

    Excited states in Ta-163 have been identified for the first time using the Cd-106(Ni-60,3p) fusion evaporation reaction. gamma rays were detected using the JUROGAM gamma-ray spectrometer and recoil discrimination was achieved using the recoil ion transport unit (RITU) gas-filled separator in conjunction with the GREAT spectrometer situated at the focal plane of the RITU. The yrast states are assigned to a strongly coupled rotational band based on a pi h(11/2) configuration. This structure exhibits large signature splitting at low spins that disappears after the paired band crossing because of the alignment of a pair of i(13/2) neutrons. This effect is ascribed to triaxial shape changes induced by the core-polarizing properties of the deformation-aligned h(11/2) proton and the rotation-aligned i(13/2) neutrons. Two additional strongly coupled band structures have been established and are discussed in terms of octupole-vibrational and two-quasiparticle excitations built on the yrast structure. The experimental results are compared with predictions from cranked-shell-model and total-Routhian-surface calculations.

  • 169.
    Sandzelius, Mikael
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Ganioglu, Ela
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Cederwall, Bo
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Hadinia, Bahrak
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Andgren, Karin
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Bäck, Torbjörn
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Johnson, Arne
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Khaplanov, Anton
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Wyss, Ramon
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    First observation of excited states in Hg-1722009In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 79, no 6, p. 064315-Article in journal (Refereed)
    Abstract [en]

    Excited states in the extremely neutron-deficient isotope Hg-172 have been established for the first time. The Ru-96(Kr-78,2n) reaction was employed to populate excited states in Hg-172 with a cross section sigma approximate to 15 nb. The highly selective recoil-decay tagging (RDT) technique was used to obtain clean in-beam gamma-ray spectra for Hg-172. The yrast ground-state band has tentatively been established up to I=6 h. The data have been interpreted within the framework of total Routhian surface and quasiparticle random phase approximation calculations.

    .

     

  • 170.
    Sandzelius, Mikael
    et al.
    KTH, School of Engineering Sciences (SCI), Physics.
    Scholey, Catherine
    Cederwall, Bo
    KTH, School of Engineering Sciences (SCI), Physics.
    Ganioglu, Ela
    KTH, School of Engineering Sciences (SCI), Physics.
    Andgren, Karin
    KTH, School of Engineering Sciences (SCI), Physics.
    Bäck, Torbjörn
    KTH, School of Engineering Sciences (SCI), Physics.
    Hadinia, Baharak
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Johnson, Arne
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Lagergren, Karin
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Wyss, Ramon
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    First identification of excited states in 169Ir2007In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 75, no 5, p. 054321-Article in journal (Refereed)
    Abstract [en]

    Gamma rays populating the alpha-decaying isomeric state in Ir-169 have been observed for the first time. The experiment employed the recoil-decay tagging method using the JUROGAM gamma-ray spectrometer, the RITU gas-filled recoil separator and the GREAT spectrometer located at the RITU focal plane. The gamma-ray cascade feeding the isomeric alpha-decaying state exhibits a rotational structure consistent with a h(11/2) proton coupled to a triaxially deformed core. The experimental results are compared with predictions from total Routhian surface calculations.

  • 171.
    Satula, Wojciech
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Wyss, Ramon
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Rafalski, Michal
    Global properties of the Skyrme-force-induced nuclear symmetry energy2006In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 74, no 1, p. 011301-Article in journal (Refereed)
    Abstract [en]

    A novel concept for the nuclear symmetry energy (NSE) is corroborated by large scale calculations. The paper firmly demonstrates that within the local density approximation, the value of the NSE coefficient, a(sym)(A), depends on two basic ingredients: the mean-level spacing, epsilon(A), and the effective strength of the isovector mean-potential, kappa(A). Surprisingly, our results reveal that these two basic ingredients of a(sym) are almost equal after rescaling them linearly by the isoscalar and the isovector effective masses, respectively. This result points towards a hidden and hitherto unresolved fundamental property of the effective nuclear interaction. In addition, our analysis yields naturally the ratio of the surface-to-volume contributions to a(sym) with a value of similar to 1.6, consistent with hydrodynamical estimates for the static dipole polarizability as well as the neutron-skin. Although the present study is restricted to energy density functionals obtained from Skyrme forces the method is general and can easily be applied to more general local energy density functionals and nonnuclear bifermionic systems.

  • 172.
    Satula, Wojtek
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Wyss, Ramon
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Zalewski, M.
    Contradicting effective mass scalings in the single-particle spectra calculated using the Skyrme energy density functional method2008In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 78, no 1, p. 011302-Article in journal (Refereed)
    Abstract [en]

    The problem of the effective mass scaling in the single-particle (s.p.) spectra calculated within the Skyrme energy density functional (EDF) method is studied. It is demonstrated that for specific pairs of orbitals like 1d(3/2)-1f(7/2) the commonly anticipated isoscalar effective mass (m*) scaling of the s.p. level splittings is almost canceled by an implicit m* scaling present in the two-body spin-orbit (SO) strength. On the other hand, the nu f(7/2)-nu f(5/2) SO splitting depends solely on the SO strength. Hence, two conflicting scaling properties appear to be at work in standard Skyrme EDF, making the theory internally inconsistent with respect to s.p. energies. It is argued that this unphysical property is, to a large extent, a consequence of the strategies and data sets used to fit these functionals. The inclusion of certain s.p. spin-orbit splittings to fit the two-body spin-orbit and the tensor interaction strengths reinstates the conventional m* scaling and improves the performance of the Skyrme EDF.

  • 173. Scholey, C.
    et al.
    Andgren, Karin
    KTH, School of Engineering Sciences (SCI), Physics.
    Bianco, L.
    Cederwall, Bo
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Darby, I. G.
    et al,
    Isomeric and ground-state properties of Pt-171(78), Os-167(76), and W-163(74)2010In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 81, no 1Article in journal (Refereed)
    Abstract [en]

    Decay paths, half-lives, and excitation energies of the i(13/2) bandheads of the neutron-deficient nuclei Pt-171, Os-167, and W-163 have been established for the first time. Gamma-ray transitions, X-rays, and internal conversion electrons have been observed, allowing internal-conversion coefficients to be measured and B(M2) reduced transition probabilities to be extracted. These results elucidate the low-lying single-quasiparticle structures and give the energy level spacings between the nu f(7/2), nu h(9/2), and nu i(13/2) quasineutron states for all three nuclei. Moreover, ground-state spin assignments have been made for the first time, along with the measurement of the alpha-decay branching ratio for Pt-171. The decay paths of the i(13/2) bandheads were followed by favored alpha decays, indicating that all three nuclei have the same I-pi = 7/2(-) ground state.

  • 174. Seliverstov, M. D.
    et al.
    Cocolios, T. E.
    Dexters, W.
    Andreyev, A. N.
    Antalic, S.
    Barzakh, A. E.
    Bastin, B.
    Buscher, J.
    Darby, I. G.
    Fedorov, D. V.
    Fedosseev, V. N.
    Flanagan, K. T.
    Franchoo, S.
    Huber, G.
    Huyse, M.
    Keupers, M.
    Koester, U.
    Kudryavtsev, Yu.
    Marsh, B. A.
    Molkanov, P. L.
    Page, R. D.
    Sjödin, Marica
    KTH, School of Engineering Sciences (SCI), Physics.
    Stefan, I.
    Van Duppen, P.
    Venhart, M.
    Zemlyanoy, S. G.
    Electromagnetic moments of odd-A Po-193-203,Po-211 isotopes2014In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 89, no 3, p. 034323-Article in journal (Refereed)
    Abstract [en]

    Hyperfine splitting parameters have been measured for the neutron-deficient odd-mass polonium isotopes and isomers Po-193-203(g,m), Po-209,Po-211. The measurement was performed at the ISOLDE (CERN) online mass separator using the in-source resonance ionization spectroscopy technique. The magnetic dipole moments mu and spectroscopic electric quadrupole moments Q(S) have been deduced. Their implication for the understanding of nuclear structure in the vicinity of the closed proton shell at Z = 82 and the neutron mid-shell at N = 104 is discussed. For the most neutron-deficient nuclei (A = 193,195,197), a deviation of mu and QS from the nearly constant values for heavier polonium nuclei was observed. Particle-plus-rotor calculations with static oblate deformation describe the electromagnetic moments for these nuclei well, provided a gradual increase of a mean deformation when going to lighter masses is assumed for the polonium nuclei with A < 198.

  • 175. Sheikh, J. A.
    et al.
    Wyss, Ramon
    KTH, Superseded Departments, Physics.
    Isovector and isoscalar superfluid phases in rotating nuclei2000In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 6205, no 5Article in journal (Refereed)
    Abstract [en]

    The subtle interplay between the two nuclear superfluids, isovector T=1, and isoscalar T=0 phases are investigated in an exactly soluble model. It is shown that T=1 and T=0 pair modes decouple in the exact calculations with the T=1 pair energy being independent of the T=0 pair strength and vice verse. In the rotating field, the isoscalar correlations remain constant in contrast to the well-known quenching of isovector pairing. An increase of the isoscalar (J=1,T=0) pair field results in a delay of the hand crossing frequency. This behavior is shown to be present only near the N=Z line and its experimental confirmation would imply a strong signature for isoscalar pairing collectivity. The solutions of the exact model are also discussed in the Hartree-Fock-Bogoliubov approximation.

  • 176. Shen, S. F.
    et al.
    Zheng, S. J.
    Xu, F. R.
    Wyss, Ramon A
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Stability of triaxial shapes in ground and excited states of even-even nuclei in the A similar to 70 region2011In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 84, no 4, p. 044315-Article in journal (Refereed)
    Abstract [en]

    Total-Routhian-surface calculations by means of the pairing-deformation-frequency self-consistent cranked shell model have been carried out for even-even germanium and selenium isotopes to search for possible stable triaxial deformations of nuclear states. The maximum triaxiality of |gamma| approximate to 30 degrees. is found in the ground and excited rotational states of the nuclei (64,74)Ge. The calculations are compared with available experimental data, giving a general agreement with observed triaxiality in the isotopes.

  • 177. Singh, B. S. Nara
    et al.
    Steer, A. N.
    Jenkins, D. G.
    Wadsworth, R.
    Bentley, M. A.
    Davies, P. J.
    Glover, R.
    Pattabiraman, N. S.
    Lister, C. J.
    Grahn, T.
    Greenlees, P. T.
    Jones, P.
    Julin, R.
    Juutinen, S.
    Leino, M.
    Nyman, M.
    Pakarinen, J.
    Rahkila, P.
    Saren, J.
    Scholey, C.
    Sorri, J.
    Uusitalo, J.
    Butler, P. A.
    Dimmock, M.
    Joss, D. T.
    Thomson, J.
    Cederwall, Bo
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Hadinia, B.
    Sandzelius, M.
    Coulomb shifts and shape changes in the mass 70 region2007In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 75, no 6Article in journal (Refereed)
    Abstract [en]

    The technique of recoil beta tagging has been developed which allows prompt gamma decays in nuclei from excited states to be correlated with electrons from their subsequent short-lived beta decay. This technique is ideal for studying nuclei very far from stability and improves in sensitivity for very short-lived decays and for high decay Q-values. The method has allowed excited states in Y-78 to be observed for the first time, as well as an extension in the knowledge of T=1 states in Rb-74. From this new information it has been possible to compare Coulomb energy differences (CED) between T=1 states in Br-70/Se-70, Rb-74/Kr-74, and Y-78/Sr-78. The A=70 CED exhibit an anomalous behavior which is inconsistent with all other known CED. This behavior may be accounted for qualitatively in terms of small variations in the Coulomb energy arising from shape changes.

  • 178. Smith, J. F.
    et al.
    Chiara, C. J.
    Carpenter, M. P.
    Davids, C. N.
    Devlin, M.
    Fossan, D. B.
    Freeman, S. J.
    Janssens, R. V. F.
    LaFosse, D. R.
    Sarantites, D. G.
    Seweryniak, D.
    Starosta, K.
    Wadsworth, R.
    Wilson, A. N.
    Wyss, Ramon
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Excited states and signature inversion in Cs-1162006In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 74, no 3, p. 034310-Article in journal (Refereed)
    Abstract [en]

    Excited states have been observed for the first time in the very neutron-deficient, odd-odd nucleus, Cs-116(55)61. The assignment to Cs-116 has been made by the detection of gamma rays in coincidence with evaporated charged particles and with evaporation residues. The observed states form a rotational band which has been assigned to the nu(h(11/2)) circle times pi(h(11/2)) configuration. Tentative spin assignments have been made on the basis of systematic comparisons with neighboring cesium isotopes. A low-spin signature inversion is observed in the band at a rotational frequency of about 0.23 MeV/h. The observed signature inversions in the odd-odd Cs116-126 isotopes have been compared with the results of extended total Routhian surface calculations, in which signature inversion arises as a consequence of quadrupole-pairing correlations and triaxial deformation. As previously shown for some of the odd-odd A similar or equal to 120 isotopes, the calculations reproduce the signature inversions reasonably well.

  • 179. Soderstrom, P. -A
    et al.
    Recchia, F.
    Nyberg, J.
    Gadea, A.
    Lenzi, S. M.
    Poves, A.
    Atac, A.
    Aydin, S.
    Bazzacco, D.
    Bednarczyk, P.
    Bellato, M.
    Birkenbach, B.
    Bortolato, D.
    Boston, A. J.
    Boston, H. C.
    Bruyneel, B.
    Bucurescu, D.
    Calore, E.
    Cederwall, Bo
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Charles, L.
    Chavas, J.
    Colosimo, S.
    Crespi, F. C. L.
    Cullen, D. M.
    de Angelis, G.
    Desesquelles, P.
    Dosme, N.
    Duchene, G.
    Eberth, J.
    Farnea, E.
    Filmer, F.
    Gorgen, A.
    Gottardo, A.
    Grebosz, J.
    Gulmini, M.
    Hess, H.
    Hughes, T. A.
    Jaworski, G.
    Jolie, J.
    Joshi, P.
    Judson, D. S.
    Jungclaus, A.
    Karkour, N.
    Karolak, M.
    Kempley, R. S.
    Khaplanov, Anton
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Korten, W.
    Ljungvall, J.
    Lunardi, S.
    Maj, A.
    Maron, G.
    Meczynski, W.
    Menegazzo, R.
    Mengoni, D.
    Michelagnoli, C.
    Molini, P.
    Napoli, D. R.
    Nolan, P. J.
    Norman, M.
    Obertelli, A.
    Podolyak, Zs.
    Pullia, A.
    Quintana, B.
    Redon, N.
    Regan, P. H.
    Reiter, P.
    Robinson, A. P.
    Sahin, E.
    Simpson, J.
    Salsac, M. D.
    Smith, J. F.
    Stezowski, O.
    Theisen, Ch.
    Tonev, D.
    Unsworth, C.
    Ur, C. A.
    Valiente-Dobon, J. J.
    Wiens, A.
    High-spin structure in K-402012In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 86, no 5, p. 054320-Article in journal (Refereed)
    Abstract [en]

    High-spin states of K-40 have been populated in the fusion-evaporation reaction C-12(Si-30,np)K-40 and studied by means of gamma-ray spectroscopy techniques using one triple-cluster detector of the Advanced Gamma Tracking Array at the Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Legnaro. Several states with excitation energy up to 8 MeV and spin up to 10(-) have been discovered. These states are discussed in terms of J = 3 and T = 0 neutron-proton hole pairs. Shell-model calculations in a large model space have shown good agreement with the experimental data for most of the energy levels. The evolution of the structure of this nucleus is here studied as a function of excitation energy and angular momentum.

  • 180. Sohler, D
    et al.
    Cederkall, J
    Lipoglavsek, M
    Dombradi, Z
    Gorska, M
    Persson, J
    Seweryniak, D
    Ahmad, I
    Atac, A
    Bark, R A
    Blomqvist, J
    Carpenter, M P
    Cederwall, Bo
    Davids, C N
    Fahlander, C
    Fischer, S M
    Grawe, H
    Hackman, G
    Janssens, R V F
    Johnson, A
    Kerek, A
    Klamra, W
    Kownacki, J
    Lister, C J
    Mitarai, S
    Nisius, D
    Norlin, L O
    Nyberg, J
    Poli, G
    Reiter, P
    Ressler, J J
    Roth, H A
    Schwartz, J
    Sletten, G
    Uusitalo, J
    Walters, W B
    Weiszflog, M
    Yrast states of the proton drip line nucleus Sb-1061999In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 59, no 3, p. 1324-1327Article in journal (Refereed)
    Abstract [en]

    Yrast states of Sb-106 have been investigated in the Fe-54(Ni-58, alpha pn) reaction using in-beam gamma-spectroscopic methods and in the Cr-50(Ni-58,pn) reaction performing delayed gamma and conversion electron studies. A new isomeric state was found at 103 keV with t(1/2) = 232(21) ns. The number of start's and transitions in the proposed level scheme have been doubled. The experimental results are discussed within the framework of the shell model. [S0556-2813(99)08502-7].

  • 181. Stanoiu, M.
    et al.
    Kerek, Andras
    KTH, Superseded Departments, Physics.
    Van Der Marel, Hans
    KTH, School of Engineering Sciences (SCI), Physics.
    Yamamoto, A.
    et.,
    N=14 and 16 shell gaps in neutron-rich oxygen isotopes2004In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 69, no 3Article in journal (Refereed)
    Abstract [en]

    In-beam gamma-ray spectroscopy using fragmentation reactions of both stable and radioactive beams has been performed in order to study the structure of excited states in neutron-rich oxygen isotopes with masses ranging from A=20 to 24. For the produced fragments, gamma-ray energies, intensities, and gamma-gamma coincidences have been measured. Based on this information new level schemes are proposed for O-21,O-22 up to the neutron separation energy. The nonobservation of any gamma-decay branch from O-23 and O-24 suggests that their excited states lie above the neutron decay thresholds. From this, as well as from the level schemes proposed for O-21 and O-22, the size of the N=14 and 16 shell gaps in oxygen isotopes is discussed in the light of shell-model calculations.

  • 182. Stanoiu, M.
    et al.
    Sohler, D.
    Sorlin, O.
    Azaiez, F.
    Dombradi, Z.
    Brown, B. A.
    Belleguic, M.
    Borcea, C.
    Bourgeois, C.
    Dlouhy, Z.
    Elekes, Z.
    Fulop, Z.
    Grevy, S.
    Guillemaud-Mueller, D.
    Ibrahim, F.
    Kerek, Andras
    KTH, School of Technology and Health (STH), Medical Engineering.
    Krasznahorkay, A.
    Lewitowicz, M.
    Lukyanov, S. M.
    Mandal, S.
    Mrazek, J.
    Negoita, F.
    Penionzhkevich, Y. E.
    Podolyak, Z.
    Roussel-Chomaz, P.
    Saint-Laurent, M. G.
    Savajols, H.
    Sletten, G.
    Timar, J.
    Timis, C.
    Yamamoto, A.
    Disappearance of the N=14 shell gap in the carbon isotopic chain2008In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 78, no 3Article in journal (Refereed)
    Abstract [en]

    The structure of C-17-20(6) nuclei was investigated by means of the in-beam gamma-ray spectroscopy technique using fragmentation reactions of radioactive beams. Based on particle-gamma and particle-gamma gamma coincidence data, level schemes are constructed for the neutron-rich C17-20 nuclei. The systematics of the first excited 2(+) states in the carbon isotopes is extended for the first time to A = 20 showing that in contrast to the case of the oxygen isotopes, the N = 14 subshell closure disappears. Experimental results are compared with shell-model calculations. Agreement between them is found only if a reduced neutron-neutron effective interaction is used. Implications of this reduced interaction in some properties of weakly bound neutron-rich Carbon are discussed.

  • 183. Stanoiu, M.
    et al.
    Sohler, D.
    Sorlin, O.
    Dombradi, Zs.
    Azaiez, F.
    Brown, B. A.
    Borcea, C.
    Bourgeois, C.
    Elekes, Z.
    Fueloep, Zs.
    Grevy, S.
    Guillemaud-Mueller, D.
    Ibrahim, F.
    Kerek, Andras
    KTH, School of Technology and Health (STH), Medical Engineering.
    Krasznahorkay, A.
    Lewitowicz, M.
    Lukyanov, S. M.
    Mrazek, J.
    Negoita, F.
    Penionzhkevich, Yu. -E.
    Podolyak, Zs.
    Porquet, M. G.
    Roussel-Chomaz, P.
    Saint-Laurent, M. G.
    Savajols, H.
    Sletten, G.
    Timar, J.
    Timis, C.
    Spectroscopy of (26)F2012In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 85, no 1, p. 017303-Article in journal (Refereed)
    Abstract [en]

    The structure of the weakly bound (26)(9)F(17) odd-odd nucleus, produced from (27,28)Na nuclei, has been investigated at GANIL by means of the in-beam gamma-ray spectroscopy technique. A single gamma-line is observed at 657(7) keV in (26)(9)F which has been ascribed to the decay of the excited J = 2(+) state to the J = 1(+) ground state. The possible presence of intruder negative parity states in (26)F is also discussed.

  • 184. Stefanova, E. A.
    et al.
    Stefanescu, I.
    de Angelis, G.
    Curien, D.
    Eberth, J.
    Farnea, E.
    Gadea, A.
    Gersch, G.
    Jungclaus, A.
    Lieb, K. P.
    Martinez, T.
    Schwengner, R.
    Steinhardt, T.
    Thelen, O.
    Weisshaar, D.
    Wyss, Ramon
    KTH, Superseded Departments, Physics.
    Four-quasiparticle alignments in Ge-662003In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 67, no 5Article in journal (Refereed)
    Abstract [en]

    The neutron-deficient nucleus Ge-66 was populated at high spin in two experiments using the reaction Ca-40(S-32,alpha2p) at beam energies of 105 and 95 MeV. In the first experiment, a self-supporting Ca-40 target was used, while a gold-backed target of similar thickness was used in the second experiment. gamma rays were detected with the EUROBALL array, combined with the charged-particle detector array EUCLIDES and the Neutron Wall. The level scheme of Ge-66 was extended up to Eapproximate to18 MeV and I-pi=(23(-)). Above angular momentum 10(+), we found two sequences, connected by energetically staggered DeltaI=1 M1 transitions. The total Routhian surface calculations describe Ge-66 at lower spins as a gamma-soft nucleus having a moderate deformation of beta(2)approximate to0.23, while a triaxial deformation is predicted for the band structures above I-pi=10(+). To our knowledge, this is the first observation of staggered M1 transitions in a deformed four-quasiparticle pi(g(9/2)(2))nu(g(9/2)(2)) structure.

  • 185. Sylvan, G N
    et al.
    Doring, J
    Johns, G D
    Tabor, S L
    Gross, C J
    Baktash, C
    Jin, H Q
    Stracener, D W
    Hua, P F
    Korolija, M
    LaFosse, D R
    Sarantites, D G
    Cristancho, F
    Landulfo, E
    Saladin, J X
    Cederwall, Bo
    Lee, I Y
    Macchiavelli, A O
    Rathbun, W
    VanderMolen, A
    Deformation driving intruder orbitals in Kr-771997In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 56, no 2, p. 772-781Article in journal (Refereed)
    Abstract [en]

    High-spin states in Kr-77 were identified via analysis of prompt gamma-gamma coincidences in the Ni-58(Si-29,2 alpha 2p) reaction at 128 MeV at the Gammasphere facility. Evaporation channel selection was achieved using the 95 element Microball charged-particle detector. 27 new states and 42 new transitions were found, The positive-parity bands were confirmed and the alpha=-1/2 band extended to 39/2(+). The negative-parity signature pair was extended to 31/2(-) and 37/2(-). Two new high-lying negative-parity bands were found extending from a state of spin I = 15/2 and energy 2.6 MeV to 17.4 MeV at I = (55/2). The new bands appear highly deformed and become yrast at high spin. A three-quasiparticle structure based on deformation driving, low-K unique-parity and intruder orbitals is suggested for them.

  • 186. Taylor, M. J.
    et al.
    Cullen, D. M.
    Procter, M. G.
    Bäck, Torbjörn
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Cederwall, Bo
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Doncel, Maria
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Braunroth, T.
    Dewald, A.
    Pakarinen, J.
    Grahn, T.
    Greenlees, P. T.
    Auranen, K.
    Jakobsson, U.
    Julin, R.
    Juutinen, S.
    Herzan, A.
    Konki, J.
    Leino, M.
    Liotta, R.
    Partanen, J.
    Peura, P.
    Rahkila, P.
    Ruotsalainen, P.
    Sandzelius, M.
    Saren, J.
    Sorri, J.
    Stolze, S.
    Uusitalo, J.
    Liang, W. Y.
    Xu, F. R.
    Competing single-particle and collective states in the low-energy structure of I-1132013In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 88, no 5, p. 054307-Article in journal (Refereed)
    Abstract [en]

    To understand the low-energy structure of the neutron deficient iodine isotopes, lifetimes for the low-lying 9/2(+) and 11/2(+) positive-parity states in I-113 have been measured as tau = 28(4) ps and tau = 3.7(7) ps, respectively. The lifetime for the 11/2(-) state, which feeds the 9/2(+) and 11/2(+) states, was remeasured with improved accuracy as tau = 216(7) ps. The reduced transition probability, B(E2) = 32(5) W.u., for the 9/2(+) -> 5/2(+) transition agrees with that calculated within the shell model using a Hamiltonian based on the charge-dependent Bonn nucleon-nucleon interaction. In contrast, the much larger transition probability, B(E2) = 209(39) W.u., measured for the 11/2(+) -> 7/2(+) transition has been interpreted, with the aid of configuration-constrained total Routhian surface calculations, as resulting from a slightly gamma-soft rotor with an associated quadrupole deformation of beta(2) approximate to 0.18. Remarkably similar reduced E1 transition probabilities of 5.5(5) x 10(-4) and 4.9(5) x 10(-4) W.u. were deduced for the 11/2(-) -> 9/2(+) and 11/2(-) -> 11/2(+) transitions, respectively, which feed apparently dissimilar but competing structures.

  • 187. Taylor, M. J.
    et al.
    Cullen, D. M.
    Procter, M. G.
    Smith, A. J.
    McFarlane, A.
    Twist, V.
    Alharshan, G. A.
    Ferreira, L. S.
    Maglione, E.
    Auranen, K.
    Grahn, T.
    Greenlees, P. T.
    Hauschild, K.
    Herzan, A.
    Jakobsson, U.
    Julin, R.
    Juutinen, S.
    Ketelhut, S.
    Konki, J.
    Leino, M.
    Lopez-Martens, A.
    Pakarinen, J.
    Partanen, J.
    Peura, P.
    Rahkila, P.
    Rinta-Antila, S.
    Ruotsalainen, P.
    Sandzelius, M.
    Saren, J.
    Scholey, C.
    Sorri, J.
    Stolze, S.
    Uusitalo, J.
    Doncel, Maria
    KTH, School of Engineering Sciences (SCI), Physics.
    Oblately deformed isomeric proton-emitting state in Lu-1512015In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 91, no 4, article id 044322Article in journal (Refereed)
    Abstract [en]

    Gamma rays from excited states feeding a proton-emitting isomeric-state in Lu-151 have been observed for the first time. Comparison with state-of-the-art nonadiabatic quasiparticle calculations indicates an oblately deformed, 3/2(+) proton-emitting state with a quadrupole deformation of beta(2) = -0.11. The calculations suggest an increase in quadrupole deformation, to beta(2) = -0.18, with increasing spin which is understood in terms of the mixing of Nilsson states at the Fermi surface. It is also shown that the proton decay half-life is consistent with that from a 3/2(+) state with a quadrupole deformation of beta(2) = -0.12.

  • 188. Thomson, J.
    et al.
    Joss, D. T.
    Paul, E. S.
    Scholey, C.
    Simpson, J.
    Erturk, S.
    Bianco, L.
    Cederwall, Bo
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Darby, I. G.
    Eeckhaudt, S.
    Gomez-Hornillos, M. B.
    Grahn, T.
    Greenlees, P. T.
    Hadinia, Baharak
    KTH, School of Engineering Sciences (SCI), Physics.
    Jones, P.
    Julin, R.
    Juutinen, S.
    Ketelhut, S.
    Leino, M.
    Nyman, M.
    O'Donnell, D.
    Page, R. D.
    Pakarinen, J.
    Rahkila, P.
    Rowley, N.
    Sandzelius, Mikael
    KTH, School of Engineering Sciences (SCI), Physics.
    Sapple, P. J.
    Saren, J.
    Sorri, J.
    Uusitalo, J.
    Competing quasiparticle configurations in W-1632010In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 81, no 1Article in journal (Refereed)
    Abstract [en]

    Excited states in the neutron-deficient nuclide W-163 were investigated using the Cd-106(Ni-60, 2pn)W-163 reaction at a beam energy of 270 MeV. The level scheme for W-163 was extended significantly with the observation of five new band structures. The yrast band based on a 13/2(+) isomeric state is extended up to (57/2(+)). Two band structures were established on the 7/2(-) ground state. Quasiparticle configuration assignments for the new band structures were made on the basis of cranked Woods-Saxon shell-model calculations. The results reported in this article suggest that the negative-parity nu(f(7/2), h(9/2)) orbitals are responsible for the first rotational alignment in the yrast band.

  • 189.
    Thörngren Engblom, Pia
    et al.
    Uppsala universitet, Institutionen för kärn- och partikelfysik.
    Keleta, S. Negasi
    Uppsala universitet, Institutionen för kärn- och partikelfysik.
    Cappellaro, F.
    Uppsala universitet, Institutionen för kärn- och partikelfysik.
    Höistad, Bo
    Uppsala universitet, Institutionen för kärn- och partikelfysik.
    Jacewicz, Marek
    Uppsala universitet, Institutionen för kärn- och partikelfysik.
    Johansson, Tord
    Uppsala universitet, Institutionen för kärn- och partikelfysik.
    Koch, I.
    Uppsala universitet, Institutionen för kärn- och partikelfysik.
    Kullander, Sven
    Uppsala universitet, Institutionen för kärn- och partikelfysik.
    Pettersson, Hanna
    Uppsala universitet, Institutionen för kärn- och partikelfysik.
    Schönning, Karin
    Uppsala universitet, Institutionen för kärn- och partikelfysik.
    Zlomanczuk, Jozef
    Uppsala universitet, Institutionen för kärn- och partikelfysik.
    Calén, Hans
    Uppsala universitet, The Svedberg-laboratoriet.
    Fransson, Kjell
    Uppsala universitet, The Svedberg-laboratoriet.
    Kupsc, Andrzej
    Uppsala universitet, The Svedberg-laboratoriet.
    Marciniewski, Pawel
    Uppsala universitet, The Svedberg-laboratoriet.
    Wolke, Magnus
    Uppsala universitet, The Svedberg-laboratoriet.
    Pauly, C.
    Demiroers, L.
    Scobel, W.
    Stepaniak, J.
    Zabierowski, J.
    Bashkanov, M.
    Clement, H.
    Khakimova, O.
    Kren, F.
    Skorodko, T.
    Anisotropy in the pion angular distribution of the reaction pp -> pp pi(0) at 400 MeV2007In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 76, no 1, p. 011602-Article in journal (Refereed)
    Abstract [en]

    The reaction pp -> pp pi(0) was studied with the WASA detector at the CELSIUS storage ring. The center of mass angular distribution of the pi(0) was obtained by detection of the gamma decay products together with the two outgoing protons and found to be anisotropic with a negative second derivative slope, in agreement with the theoretical predictions from a microscopic calculation.

  • 190.
    Tippawan, U.
    et al.
    Department of Neutron Research, Uppsala University, Sweden.
    Ataç, Ayşe
    Department of Neutron Research, Uppsala University, Sweden.
    Koning, A.J
    Nuclear Research and Consultancy Group, Petten, Netherlands.
    et, al
    Light-ion production in the interaction of 96 MeV neutrons with oxygen2006In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 73, no 3Article in journal (Refereed)
    Abstract [en]

    Double-differential cross sections are reported for light-ion (p, d, t, (3)He, and alpha) production in oxygen induced by 96 MeV neutrons. Energy spectra are measured at eight laboratory angles from 20 degrees to 160 degrees in steps of 20 degrees. Procedures for data taking and data reduction are presented. Deduced energy-differential and production cross sections are reported. Experimental cross sections are compared to theoretical reaction model calculations and experimental data at lower neutron energies in the literature. The measured proton data agree reasonably well with the results of the model calculations, whereas the agreement for the other particles is less convincing. The measured production cross sections for protons, deuterons, tritons, and alpha particles support the trends suggested by data at lower energies.

  • 191. Tippawan, U.
    et al.
    Pomp, S.
    Ataç, Ayşe
    Department of Neutron Research, Uppsala University, Sweden.
    Bergenwall, B.
    Blomgren, J.
    Dangtip, S.
    Hildebrand, A.
    Johansson, C.
    Klug, J.
    Mermod, P.
    Nilsson, L.
    Osterlund, M.
    Olsson, N.
    Elmgren, K.
    Jonsson, O.
    Prokofiev, A. V.
    Renberg, P.-U.
    Nadel-Turonski, P.
    Corcalciuc, V.
    Watanabe, Y.
    Koning, A.
    Light-ion production in the interaction of  96 MeV neutrons with silicon2004In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 69, no 6Article in journal (Refereed)
    Abstract [en]

    Double-differential cross sections for light-ion (p, d, t, He-3, and alpha) production in silicon, induced by 96 MeV neutrons, are reported. Energy spectra are measured at eight laboratory angles from 20degrees to 160degrees in steps of 20degrees. Procedures for data taking and data reduction are presented. Deduced energy-differential, angle-differential, and production cross sections are reported. Experimental cross sections are compared to theoretical reaction model calculations and experimental data in the literature.

  • 192. Titarenko, Yu. E.
    et al.
    Batyaev, V. F.
    Butko, M. A.
    Dikarev, D. V.
    Florya, S. N.
    Pavlov, K. V.
    Titarenko, A. Yu.
    Tikhonov, R. S.
    Zhivun, V. M.
    Ignatyuk, A. V.
    Mashnik, S. G.
    Boudard, A.
    Leray, S.
    David, J-C
    Cugnon, J.
    Mancusi, D.
    Yariv, Y.
    Kumawat, H.
    Nishihara, K.
    Matsuda, N.
    Mank, G.
    Gudowski, Waclaw
    KTH, School of Engineering Sciences (SCI), Physics, Reactor Physics.
    Verification of high-energy transport codes on the basis of activation data2011In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 84, no 6, p. 064612-Article in journal (Refereed)
    Abstract [en]

    Nuclide production cross sections measured at the Institute for Theoretical and Experimental Physics (ITEP) for the targets of (nat)Cr, (56)Fe, (nat)Ni, (93)Nb, (181)Ta, (nat)W, (nat)Pb, and (209)Bi irradiated by protons with energies from 40 to 2600 MeV were used to estimate the predictive accuracy of several popular high-energy transport codes. A general agreement of the ITEP data with the data obtained by other groups, including the numerous GSI data measured by the inverse kinematics method was found. Simulations of the measured data were performed with the MCNPX (BERTINI and ISABEL options), CEM03.02, INCL4.2 + ABLA, INCL4.5 + ABLA07, PHITS, and CASCADE.07 codes. Deviation factors between the calculated and experimental cross sections have been estimated for each target and for the whole energy range covered by our measurements. Two-dimensional diagrams of deviation factor values were produced for estimating the predictive power of every code for intermediate, not measured masses of nuclei targets and bombarding energies of protons. Further improvements of all tested here codes are recommended. In addition, new measurements at ITEP of nuclide yields from the (208)Pb target irradiated by 500-MeV protons are presented. A good agreement between these new data and the GSI measurements obtained by the inverse kinematics method was found.

  • 193. Titarenko, Yu. E.
    et al.
    Batyaev, V. F.
    Titarenko, A. Yu.
    Butko, M. A.
    Pavlov, K. V.
    Florya, S. N.
    Tikhonov, R. S.
    Mashnik, S. G.
    Ignatyuk, A. V.
    Titarenko, N. N.
    Gudowski, Waclaw
    KTH, School of Engineering Sciences (SCI), Physics, Reactor Physics.
    Tesinsky, Milan
    KTH, School of Engineering Sciences (SCI), Physics, Reactor Physics.
    Persson, Carl-Magnus
    KTH, School of Engineering Sciences (SCI), Physics, Reactor Physics.
    Abderrahim, H. Ait
    Kumawat, H.
    Duarte, H.
    Cross sections for nuclide production in a Fe-56 target irradiated by 300, 500, 750, 1000, 1500, and 2600 MeV protons compared with data on a hydrogen target irradiated by 300, 500, 750, 1000, and 1500 MeV/nucleon Fe-56 ions2008In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 78, no 3, p. 034615-Article, review/survey (Refereed)
    Abstract [en]

    This work presents the cross sections for radioactive nuclide production in Fe-56( p, x) reactions determined in six experiments using 300, 500, 750, 1000, 1500, and 2600 MeV protons of the external beam from the ITEP U-10 proton accelerator. In total, 221 independent and cumulative yields of radioactive residuals of half-lives from 6.6 min to 312 d have been obtained. The radioactive product nuclide yields were determined by direct gamma-spectrometry. The measured data have been compared with the experimental data obtained elsewhere by the direct and inverse kinematics methods and with calculation results of 15 different codes that simulated hadron-nucleus interactions: MCNPX (INCL, CEM2K, BERTINI, ISABEL), LAHET (BERTINI, ISABEL), CEM03 (.01,. G1,. S1), LAQGSM03 (.01,. G1,. S1), CASCADE-2004, LAHETO, and BRIEFF. Most of the data obtained here are in a good agreement with the inverse kinematics results and disprove the results of some earlier activation measurements that were quite different from the inverse kinematics measurements. The most significant calculation-to-experiment differences are observed in the yields of the A < 30 light nuclei, indicating that further improvements in nuclear reaction models are needed, and pointing out as well to a necessity of more complete experimental measurements of such reaction products.

  • 194.
    v. Przewoski, B.
    et al.
    Indiana University Cyclotron Facility.
    Meyer, H. O.
    Indiana University.
    Balewski, J. T.
    Daehnick, W. W.
    Doskow, J.
    Haeberli, W.
    Ibald, R.
    Lorentz, B.
    Pollock, R. E.
    Pancella, P. V.
    Rathmann, F.
    Rinckel, T.
    Saha, Swapan K.
    Schwartz, B.
    Thörngren-Engblom, Pia
    Uppsala universitet, Fysiska institutionen.
    Wellinghausen, A.
    Indiana University Cyclotron Facility.
    Whitaker, T. J.
    Indiana University Cyclotron Facility.
    Wise, T.
    University of Wisconsin-Madison.
    Analyzing powers and spin correlation coefficients for p+d elastic scattering at 135 and 200 MeV2006In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 74, no 6, article id 064003Article in journal (Refereed)
    Abstract [en]

    The proton and deuteron analyzing powers and ten of the possible 12 spin correlation coefficients have been measured for p+d elastic scattering at proton bombarding energies of 135 and 200 MeV. The results are compared with Faddeev calculations using two different NN potentials. The qualitative features of the extensive data set on the spin dependence in p+d elastic scattering over a wide range of angles presented here are remarkably well explained by two-nucleon force predictions without inclusion of a three-nucleon force. The remaining discrepancies are, in general, not alleviated when theoretical three-nucleon forces are included in the calculations.

  • 195. Vajta, Zs.
    et al.
    Stanoiu, M.
    Sohler, D.
    Jansen, G. R.
    Azaiez, F.
    Dombradi, Zs.
    Sorlin, O.
    Brown, B. A.
    Belleguic, M.
    Borcea, C.
    Bourgeois, C.
    Dlouhy, Z.
    Elekes, Z.
    Fueloep, Zs.
    Grevy, S.
    Guillemaud-Mueller, D.
    Hagen, G.
    Hjorth-Jensen, M.
    Ibrahim, F.
    Kerek, Andras
    KTH, School of Engineering Sciences (SCI), Physics.
    Krasznahorkay, A.
    Lewitowicz, M.
    Lukyanov, S. M.
    Mandal, S.
    Mayet, P.
    Mrazek, J.
    Negoita, F.
    Penionzhkevich, Yu. -E.
    Podolyak, Zs.
    Roussel-Chomaz, P.
    Saint-Laurent, M. G.
    Savajols, H.
    Sletten, G.
    Timar, J.
    Timis, C.
    Yamamoto, A.
    Excited states in the neutron-rich nucleus F-252014In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 89, no 5, p. 054323-Article in journal (Refereed)
    Abstract [en]

    The structure of the nucleus F-25(9) was investigated through in-beam. gamma-ray spectroscopy of the fragmentation of Ne-26 and Na-27,Na-28 ion beams. Based on the particle-gamma and particle-gamma gamma coincidence data, a level scheme was constructed and compared with shell model and coupled-cluster calculations. Some of the observed states were interpreted as quasi-single-particle states built on top of the closed-shell nucleus O-24, while the others were described as states arising from coupling of a single proton to the 2(broken vertical bar) core excitation of O-24.

  • 196. Van de Vel, K.
    et al.
    Andreyev, A. N.
    Ackermann, D.
    Boardman, H. J.
    Cagarda, P.
    Gerl, J.
    Hessberger, F. P.
    Hofmann, S.
    Huyse, M.
    Karlgren, Daniel
    KTH, Superseded Departments, Physics.
    Kojouharov, I.
    Leino, M.
    Lommel, B.
    Munzenberg, G.
    Moore, C.
    Page, R. D.
    Saro, S.
    Van Duppen, P.
    Wyss, Ramon
    KTH, Superseded Departments, Physics.
    Fine structure in the alpha decay of Po-188,Po-1922003In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 68, no 5Article in journal (Refereed)
    Abstract [en]

    The alpha decay of Po-188,Po-192 has been reexamined in order to probe the 0(+) states in the daughter nuclei Pb-184,Pb-188 that can be associated with coexisting spherical, oblate, and/or prolate configurations. Improved values were measured for the excitation energy and the feeding alpha -decay intensity of the 0(2)(+) state in Pb-184,Pb-188 and conflicting results on the 0(3)(+) state in Pb-188 were clarified. All known cases of fine structure in the alpha decay of the even-even Po nuclei are reviewed. The reduced alpha-decay width systematics combined with potential-energy-surface calculations confirm the onset of deformation in the ground state of the polonium nuclei around the neutron midshell. An isomeric state with a half-life of 580(100)ns has been identified in Po-192 .

  • 197. Van de Vel, K.
    et al.
    Andreyev, A. N.
    Huyse, M.
    Van Duppen, P.
    Cocks, J. F. C.
    Dorvaux, O.
    Greenlees, P. T.
    Helariutta, K.
    Jones, P.
    Julin, R.
    Juutinen, S.
    Kettunen, H.
    Kuusiniemi, P.
    Leino, M.
    Muikku, M.
    Nieminen, P.
    Eskola, K.
    Wyss, Ramon
    KTH, Superseded Departments, Physics.
    Identification of low-lying proton-based intruder states in Pb189-1932002In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 65, no 6Article in journal (Refereed)
    Abstract [en]

    Low-lying proton-based intruder states have been observed in the odd-mass isotopes Pb-189,Pb-191,Pb-193 in experiments at the RITU gas-filled recoil separator. The identification has been performed by observing the fine structure in the alpha decay of the parent Po-193,Po-195,Po-197 nuclei in prompt coincidence with conversion electrons and gamma rays in the daughter lead isotopes. Along with the literature data these results establish a systematics of intruder states in the odd-mass lead isotopes from Pb-197 down to Pb-185. Interpretation of these states involves the coupling of the 1i(13/2) or 3p(3/2) odd neutron to the 0(+) state in the oblate minimum in the even-mass lead core. Conversion coefficients have been determined for some of the transitions, revealing mixing between the coexisting states. The experimental results are compared to potential energy surface calculations.

  • 198. Vandone, V.
    et al.
    Leoni, S.
    Benzoni, G.
    Blasi, N.
    Bracco, A.
    Brambilla, S.
    Boiano, C.
    Bottoni, S.
    Camera, F.
    Corsi, A.
    Crespi, F. C. L.
    Giaz, A.
    Million, B.
    Nicolini, R.
    Pellegri, L.
    Pullia, A.
    Wieland, O.
    Bortolato, D.
    de Angelis, G.
    Calore, E.
    Gottardo, A.
    Maron, G.
    Napoli, D. R.
    Rosso, D.
    Sahin, E.
    Valiente-Dobon, J. J.
    Bazzacco, D.
    Bellato, M.
    Farnea, E.
    Lunardi, S.
    Menegazzo, R.
    Mengoni, D.
    Molini, P.
    Michelagnoli, C.
    Montanari, D.
    Recchia, F.
    Ur, C. A.
    Gadea, A.
    Hueyuek, T.
    Cieplicka, N.
    Maj, A.
    Kmiecik, M.
    Atac, A.
    Akkoyun, S.
    Kaskas, A.
    Soederstroem, P. -A
    Birkenbach, B.
    Cederwall, Bo
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Coleman-Smith, P. J.
    Cullen, D. M.
    Desesquelles, P.
    Eberth, J.
    Goergen, A.
    Grebosz, J.
    Hess, H.
    Judson, D.
    Jungclaus, A.
    Karkour, N.
    Nolan, P.
    Obertelli, A.
    Reiter, P.
    Salsac, M. D.
    Stezowski, O.
    Theisen, Ch.
    Matsuo, M.
    Vigezzi, E.
    Global properties of K hindrance probed by the gamma decay of the warm rotating W-174 nucleus2013In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 88, no 3, p. 034312-Article in journal (Refereed)
    Abstract [en]

    The K hindrance to the gamma decay is studied in the warm rotating W-174 nucleus, focusing on the weakening of the selection rules of the K quantum number with increasing excitation energy. W-174 was populated by the fusion reaction of Ti-50 (at 217 MeV) on a Te-128 target, and its gamma decay was detected by the AGATA Demonstrator array coupled to a BaF2 multiplicity filter at Laboratori Nazionali di Legnaro of INFN. A fluctuation analysis of gamma coincidence matrices gives a similar number of low-K and high-K discrete excited bands. The results are compared to simulations of the gamma-decay flow based on a microscopic cranked shell model at finite temperature in which the K mixing is governed by the interplay of Coriolis force with the residual interaction. Agreement between simulations and experiment is obtained only by hindering the E1 decay between low-K and high-K bands by an amount compatible with that determined by spectroscopic studies of K isomers in the same mass region, with a similar trend with excitation energy. The work indicates that K mixing due to temperature effects may play a leading role for the entire body of discrete excited bands, which probes the onset region of K weakening.

  • 199. Wilson, A. N.
    et al.
    Wadsworth, R.
    Smith, J. F.
    Freeman, S. J.
    Leddy, M. J.
    Chiara, C. J.
    Fossan, D. B.
    LaFosse, D. R.
    Starosta, K.
    Devlin, M.
    Sarantites, D. G.
    Wilson, J. N.
    Carpenter, M. P.
    Davids, C. N.
    Janssens, R. V. F.
    Seweryniak, D.
    Wyss, Ramon
    KTH, Superseded Departments, Physics.
    High-spin structures and alignment properties in Ce-1262001In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 6305, no 5Article in journal (Refereed)
    Abstract [en]

    Excited states in Ce-126 have been observed with the GAMMASPHERE gamma -ray detector array, used in conjunction with the MICROBALL charged-particle detector. The reaction Zn-64(Zn-64, xpn alpha) (beam energy 260 MeV) was used to populate a wide range of nuclei in the neutron-deficient region with A approximate to 120. Ce-126 was populated via the 2p evaporation channel. The three previously observed bands have been extended to higher spins and some other structures have been identified. The yrast band shows evidence of a delayed neutron alignment occurring at a rotational frequency omega approximate to0.5 MeV/(h) over bar as observed in the neighboring odd-A nucleus Pr-127. One of the two excited bands shows evidence for a similar crossing at a slightly lower frequency and also exhibits a sudden gain in alignment at omega =0.57 MeV/(h) over bar. The third band may involve the coupling of a gamma -vibrational state. All three rotational bands are discussed in terms of standard and extended cranked shell model calculations.

  • 200.
    Wu, Zhe-Ying
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Qi, Chong
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Wyss, Ramon
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Liu, Hong-Liang
    Global calculations of microscopic energies and nuclear deformations: Isospin dependence of the spin-orbit coupling2015In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 92, no 2, article id 024306Article in journal (Refereed)
    Abstract [en]

    Background: The deviation between different model calculations that may occur when one goes toward regions where the masses are unknown is getting increased attention. This is related to the uncertainties of the different models which may have not been fully understood. Purpose: To explore in detail the effect of the isospin dependence of the spin-orbital force in the Woods-Saxon potential on global binding energy and deformation calculations. Method: The microscopic energies and nuclear deformations of about 1850 even-even nuclei are calculated systematically within the macroscopic-microscopic framework using three Woods-Saxon parametrizations, with different isospin dependencies, which were constructed mainly for nuclear spectroscopy calculations. Calculations are performed in the deformation space (beta(2), gamma, beta(4)). Both the monopole and doubly stretched quadrupole interactions are considered for the pairing channel. Results: The ground-state deformations obtained by the three calculations are quite similar to each other. Large differences are seen mainly in neutron-rich nuclei and in superheavy nuclei. Systematic calculations on the shape-coexisting second minima are also presented. As for the microscopic energies of the ground states, the results are also very close to each other. Only in a few cases the difference is larger than 2 MeV. The total binding energy is estimated by adding the macroscopic energy provided by the usual liquid drop model with its parameters fitted through the least square root and minimax criteria. Calculations are also compared with the results of other macroscopic-microscopic mass models. Conclusions: All the three calculations give similar values for the deformations, microscopic energies, and binding energies of most nuclei. One may expect to have a better understanding of the isospin dependence of the spin-orbital force with more data on proton- and neutron-rich nuclei.

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