Helda

Helsingin yliopisto

Helsingfors universitet

University of Helsinki

Browsing by Subject "NUCLEAR-DATA SHEETS"

Now showing items 1-5 of 5

Deformation and mixing of coexisting shapes in neutron-deficient polonium isotopes

Kesteloot, N.; Bastin, B.; Gaffney, L. P.; Wrzosek-Lipska, K.; Auranen, K.; Bauer, C.; Bender, M.; Bildstein, V.; Blazhev, A.; Boenig, S.; Bree, N.; Clement, E.; Cocolios, T. E.; Damyanova, A.; Darby, I.; De Witte, H.; Di Julio, D.; Diriken, J.; Fransen, C.; Garcia-Ramos, J. E.; Gernhaeuser, R.; Grahn, T.; Heenen, P. -H.; Hess, H.; Heyde, K.; Huyse, M.; Iwanicki, J.; Jakobsson, U.; Konki, J.; Kroell, T.; Laurent, B.; Lecesne, N.; Lutter, R.; Pakarinen, J.; Peura, P.; Piselli, E.; Prochniak, L.; Rahkila, P.; Rapisarda, E.; Reiter, P.; Scheck, M.; Seidlitz, M.; Sferrazza, M.; Siebeck, B.; Sjodin, M.; Tornqvist, H.; Traykov, E.; Van De Walle, J.; Van Duppen, P.; Vermeulen, M.; Voulot, D.; Warr, N.; Wenander, F.; Wimmer, K.; Zielinska, M. (2015)

Coulomb-excitation experiments are performed with postaccelerated beams of neutron-deficient Po-196,Po-198,Po-200,Po-202 isotopes at the REX-ISOLDE facility. A set of matrix elements, coupling the low-lying states in these isotopes, is extracted. In the two heaviest isotopes, Po-196,Po-198, the transitional and diagonal matrix elements of the 2(1)(+) state are determined. In Po-196,Po-198 multistep Coulomb excitation is observed, populating the 4(1)(+), 0(2)(+), and 2(2)(+) states. The experimental results are compared to the results from the measurement of mean-square charge radii in polonium isotopes, confirming the onset of deformation from Po-196 onwards. Three model descriptions are used to compare to the data. Calculations with the beyond-mean-field model, the interacting boson model, and the general Bohr Hamiltonian model show partial agreement with the experimental data. Finally, calculations with a phenomenological two-level mixing model hint at the mixing of a spherical structure with a weakly deformed rotational structure.
Enhanced Quadrupole and Octupole Strength in Doubly Magic Sn-132

MINIBALL Collaboration; HIE-ISOLDE Collaboration; Rosiak, D.; Seidlitz, M.; Reiter, P.; Naidja, H.; Tsunoda, Y.; Togashi, T.; Nowacki, F.; Otsuka, T.; Colo, G.; Arnswald, K.; Berry, T.; Blazhev, A.; Borge, M. J. G.; Cederkall, J.; Cox, D. M.; De Witte, H.; Gaffney, L. P.; Henrich, C.; Hirsch, R.; Huyse, M.; Illana, A.; Johnston, K.; Kaya, L.; Kroell, Th.; Benito, M. L. Lozano; Ojala, J.; Pakarinen, J.; Queiser, M.; Rainovski, G.; Rodriguez, J. A.; Siebeck, B.; Siesling, E.; Snall, J.; Van Duppen, P.; Vogt, A.; von Schmid, M.; Warr, N.; Wenander, F.; Zell, K. O. (2018)

The first 2(+) and 3(-) states of the doubly magic nucleus Sn-132 are populated via safe Coulomb excitation employing the recently commissioned HIE-ISOLDE accelerator at CERN in conjunction with the highly efficient MINIBALL array. The Sn-132 ions are accelerated to an energy of 5.49 MeV/nucleon and impinged on a Pb-206 target. Deexciting gamma rays from the low-lying excited states of the target and the projectile are recorded in coincidence with scattered particles. The reduced transition strengths are determined for the transitions 0(g.s)(+) -> 2(1)(+), 0(g.s)(+) -> 3(1)(-), and 2(1)(+) -> 3(1)(-) in Sn-132. The results on these states provide crucial information on cross-shell configurations which are determined within large-scale shell-model and Monte Carlo shell-model calculations as well as from random-phase approximation and relativistic random-phase approximation. The locally enhanced B(E2; 0(g.s)(+) -> 2(1)(+)) strength is consistent with the microscopic description of the structure of the respective states within all theoretical approaches. The presented results of experiment and theory can be considered to be the first direct verification of the sphericity and double magicity of Sn-132.
Half-life determination of Tb-155 from mass-separated samples produced at CERN-MEDICIS

Collins, S. M.; Robinson, A. P.; Ivanov, P.; Koster, U.; Cocolios, T. E.; Russell, B.; Webster, B.; Fenwick, A. J.; Duchemin, C.; Ramos, J. P.; Chevallay, E.; Jakobsson, U.; Stegemann, S.; Regan, P. H.; Stora, T. (2022)

Terbium-155 has been identified for its potential for single-photon emission computed tomography (SPECT) in nuclear medicine. For activity measurements, an accurate and precise half-life of this radionuclide is required. However, the currently evaluated half-life of 5.32(6) d with a relative standard uncertainty of 1.1% determines the precision possible. Limited literature for the half-life measurements of this radionuclide is available and all reported investigations are prior to 1970. Further measurements are therefore needed to confirm the accuracy and improve the precision of the half-life for its use in the clinical setting. Two samples produced and mass separated at the CERN-MEDICIS facility have been measured at the National Physical Laboratory by two independent techniques: liquid scintillation counting and high-purity germanium gamma-ray spectrometry. A half-life of 5.2346(36) d has been determined from the weighted mean of the half-lives determined by the two techniques. The half-life reported in this work has shown a relative difference of 1.6% to the currently evaluated half-life and has vastly improved the precision.
High-sensitivity study of levels in Al-30 following beta decay of Mg-30

Olaizola, B.; Mach, H.; Fraile, L. M.; Benito, J.; Borge, M. J. G.; Boutami, R.; Butler, P. A.; Dlouhy, Z.; Fynbo, H. O. U.; Hoff, P.; Hyldegaard, S.; Jeppesen, H. B.; Jokinen, A.; Jollet, C.; Korgul, A.; Koster, U.; Kroell, Th.; Kurcewicz, W.; Marechal, F.; Mrazek, J.; Nilsson, T.; Plociennik, W. A.; Ruchowska, E.; Schuber, R.; Schwerdtfeger, W.; Sewtz, M.; Simpson, G. S.; Stanoiu, M.; Tengblad, O.; Thirolf, P. G.; Yordanov, D. T. (2016)

gamma-ray and fast-timing spectroscopy were used to study levels in Al-30 populated following the beta(-) decay of Mg-30. Five new transitions and three new levels were located in Al-30. A search was made to identify the third 1(+) state expected at an excitation energy of similar to 2.5 MeV. Two new levels were found, at 3163.9 and 3362.5 keV, that are firm candidates for this state. Using the advanced time-delayed (ATD) beta gamma gamma (t) method we have measured the lifetime of the 243.8-keV state to be T-1/2 = 15(4) ps, which implies that the 243.8-keV transition is mainly of M1 character. Its fast B(M1; 2(+) -> 3(+)) value of 0.10(3) W.u. is in very good agreement with the USD shell-model prediction of 0.090 W.u. The 1801.5-keV level is the only level observed in this study that could be a candidate for the second excited 2(+) state.
In-beam spectroscopic study of Cf-244

Konki, J.; Sulignano, B.; Greenlees, P. T.; Theisen, Ch.; Auranen, K.; Badran, H.; Briselet, R.; Cox, D. M.; Bisso, F. Defranchi; Dobaczewski, J.; Grahn, T.; Herzan, A.; Herzberg, R. -D.; Julin, R.; Juutinen, S.; Khuyagbaatar, J.; Leino, M.; Lightfoot, A.; Pakarinen, J.; Papadakis, P.; Partanen, J.; Rahkila, P.; Sandzelius, M.; Saren, J.; Scholey, C.; Shi, Y.; Smolen, M.; Sorri, J.; Stolze, S.; Uusitalo, J. (2018)

The ground-state rotational band of the neutron-deficient californium (Z = 98) isotope 244Cf was identified for the first time and measured up to a tentative spin and parity of I I-pi = 20(+). The observation of the rotational band indicates that the nucleus is deformed. The kinematic and dynamic moments of inertia were deduced from the measured gamma-ray transition energies. The behavior of the dynamic moment of inertia revealed an up-bend due to a possible alignment of coupled nucleons in high-j orbitals starting at a rotational frequency of about (h) over bar (omega) = 0.20 MeV. The results were compared with the systematic behavior of the even-even N = 146 isotones as well as with available theoretical calculations that have been performed for nuclei in the region.