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Rotational structures have been measured using the Jurogam II and GAMMASPHERE arrays at low spin following the Gd155(α,2n)Dy157 and Nd148(C12,5n)Dy155 reactions at 25 and 65 MeV, respectively. We report high-K bands, which are conjectured to be the first candidates of a Kπ=2+γ vibrational band, built on the [505]11/2− neutron orbital, in both odd-ADy155,157 isotopes. The coupling of the first excited K=0+ states or the so-called β vibrational bands at 661 and 676 keV in Dy154 and Dy156 to the [505]11/2− orbital, to produce a Kπ=11/2− band, was not observed in both Dy155 and Dy157, respectively. The implication of these findings on the interpretation of the first excited 0+ states in the core nuclei Dy154 and Dy156 are also discussed.

The spin distribution populated in the $^{150}\mathrm{Sm}(p,t)$ reaction with 25 MeV protons has been investigated using the silicon telescope and high-purity germanium array Hyperion. Angular distributions of outgoing tritons and relative intensities of $\ensuremath{\gamma}$ rays from low-lying levels are used to deduce the initial spin distribution using statistical calculations and are compared with a semiclassical model of the $(p,t)$ reaction. Experimental and theoretical results suggest a peak strength near $4\ensuremath{\hbar}$ when gated on outgoing tritons detected in Hyperion, while the full $4\ensuremath{\pi}$ distribution may peak near $2\ensuremath{\hbar}$. Additionally, the average $\ensuremath{\gamma}$-neutron branching ratio is determined from the data with the aid of one of two new codes presented in this work. The analysis is extended to other recent studies of $^{152,154}\mathrm{Sm}(p,t)$ to form systematics of the spin-dependence of the surrogate method applied to heavy nuclei in the transitional to deformed region.

New levels and $\ensuremath{\gamma}$-ray transitions were identified in $^{150,152}\mathrm{Sm}$ utilizing the $(p,t)$ reaction and particle-$\ensuremath{\gamma}$ coincidence data. A large, peak-like structure observed between 2.3--3.0 MeV in excitation energy in the triton energy spectra was also investigated. The orbital angular-momentum transfer was probed by comparing the experimental angular distributions of the outgoing tritons to calculated distorted wave Born approximation curves. The angular distributions of the outgoing tritons populating the peak-like structure are remarkably similar in the two reactions and are significantly different from the angular distributions associated with the nearby continuum region. Relative partial cross sections for the observed levels, angle averaged between 34 and 58 degrees, were measured. In $^{150}\mathrm{Sm}$, 39(4)% of the strength of the peak-like structure could be accounted for by the observed discrete states. This compares with a value of 93(15)% for $^{152}\mathrm{Sm}$.

Author(s): Henry, TW; Bentley, MA; Clark, RM; Davies, PJ; Bader, VM; Baugher, T; Bazin, D; Beausang, CW; Berryman, JS; Bruce, AM; Campbell, CM; Crawford, HL; Cromaz, M; Fallon, P; Gade, A; Henderson, J; Iwasaki, H; Jenkins, DG; Lee, IY; Lemasson, A; Lenzi, SM; Macchiavelli, AO; Napoli, DR; Nichols, AJ; Paschalis, S; Petri, M; Recchia, F; Rissanen, J; Simpson, EC; Stroberg, SR; Wadsworth, R; Weisshaar, D; Wiens, A; Walz, C | Abstract: Background: Triplet energy differences (TED) can be studied to yield information on isospin-non-conserving interactions in nuclei. Purpose: The systematic behavior of triplet energy differences (TED) of T=1, Jπ=2+ states is examined. The A=62 isobar is identified as having a TED value that deviates significantly from an otherwise very consistent trend. This deviation can be attributed to the tentative assignments of the pertinent states in Ga62 and Ge62. Methods: An in-beam γ-ray spectroscopy experiment was performed to identify excited states in Ga62 using Gamma-Ray Energy Tracking In-Beam Nuclear Array with the S800 spectrometer at NSCL using a two-nucleon knockout approach. Cross-section calculations for the knockout process and shell-model calculations have been performed to interpret the population and decay properties observed. Results: Using the systematics as a guide, a candidate for the transition from the T=1, 2+ state is identified. However, previous work has identified similar states with different Jπ assignments. Cross-section calculations indicate that the relevant T=1, 2+ state should be one of the states directly populated in this reaction. Conclusions: As spins and parities were not measurable, it is concluded that an unambiguous identification of the first T=1, 2+ state is required to reconcile our understanding of TED systematics.

The exact nature of the lowest Kπ=2+ rotational bands in all deformed nuclei remains obscure. Traditionally they are assumed to be collective vibrations of the nuclear shape in the γ degree of freedom perpendicular to the nuclear symmetry axis. Very few such γ bands have been traced past the usual backbending rotational alignments of high-j nucleons. We have investigated the structure of positive-parity bands in the N=90 nucleus Dy156, using the Nd148(C12,4n)Dy156 reaction at 65 MeV, observing the resulting γ-ray transitions with the Gammasphere array. The even- and odd-spin members of the Kπ=2+γ band are observed up to 32+ and 31+, respectively. This rotational band faithfully tracks the ground-state configuration to the highest spins. The members of a possible γ vibration built on the aligned yrast S band are observed up to spins 28+ and 27+. An even-spin positive-parity band, observed up to spin 24+, is a candidate for an aligned S band built on the seniority-zero configuration of the 0+2 state at 676 keV. The crossing of this band with the 0+2 band is at ℏωc=0.28(1)MeV and is consistent with the configuration of the 0+2 band not producing any blocking of the monopole pairing.

The standard γ-ray energy calibration source 152Eu is well known based on the 13.5 y decay of its ground state. Nevertheless, in addition to this decay 152Eu also has two relatively long-lived isomeric states: a 9 h Jπ=0- state at E*=46 keV and a 96 min Jπ=8- state at E*=148 keV. Here we report a new measurement of the half-lives of both of these isomeric states. Excited states in 152Eu were populated following the 154Sm (p,3n) reaction using a 25 MeV proton beam from the K-150 cyclotron at the Cyclotron Institute of Texas A&M University. Post irradiation, γ rays from the de-excitation of the long lived isomeric states were measured using the six BGO shielded high-purity germanium (HPGe) clover detectors that are part of the STARLiTeR array. The half-life of the Jπ=8- isomer 152m2Eu was obtained by measuring the decrease in intensity of the 90 keV γ ray from the cascade to the ground state. The half-life of this state was measured to be 95.8(4) min which is in agreement with and significantly more precise than the previously measured value of 96(1) min. In a manner similar to the ground state the second long-lived isomer 151m1Eu, the Jπ=0- state atmore » 46 keV, β decays to excited states in 152Gd and 152Sm. Also, the half-life of this state was measured to be 9.39(7) h using five γ-ray transitions.« less

Low-spin single quasineutron levels in $^{153}\mathrm{Gd}$ and $^{157}\mathrm{Gd}$ have been studied following the $^{154}\mathrm{Gd}$($p,d\ensuremath{-}\ensuremath{\gamma}$)$^{153}\mathrm{Gd}$ and $^{158}\mathrm{Gd}$($p,d\ensuremath{-}\ensuremath{\gamma}$)$^{157}\mathrm{Gd}$ reactions. A combined Si telescope and high-purity germanium array was utilized, allowing $d\text{\ensuremath{-}}\ensuremath{\gamma}$ and $d\text{\ensuremath{-}}\ensuremath{\gamma}\text{\ensuremath{-}}\ensuremath{\gamma}$ coincidence measurements. Almost all of the established low-excitation-energy, low-spin structures were confirmed in both $^{153}\mathrm{Gd}$ and $^{157}\mathrm{Gd}$. Several new levels and numerous new $\ensuremath{\gamma}$ rays are observed in both nuclei, particularly for ${E}_{x}\ensuremath{\ge}1$ MeV. Residual effects of a neutron subshell closure at $N=64$ are observed in the form of a large excitation energy gap in the single quasineutron level schemes.

The $^{236}\mathrm{Pu}(n,f)$, $^{237}\mathrm{Pu}(n,f)$ and $^{238}\mathrm{Pu}(n,f)$ cross sections have been inferred by utilizing the surrogate ratio method. Targets of $^{239}\mathrm{Pu}$ and $^{235}\mathrm{U}$ were bombarded with 28.5-MeV protons, and the light ion recoils, as well as fission fragments, were detected using the STARS detector array at the K150 Cyclotron at the Texas A cyclotron facility. The ($p$, $tf$) reaction on $^{239}\mathrm{Pu}$ and $^{235}\mathrm{U}$ targets was used to deduce the $\ensuremath{\sigma}$ $(^{236}\mathrm{Pu}(n,f))/\ensuremath{\sigma}$$(^{232}\mathrm{U}(n,f))$ ratio, and the $^{236}\mathrm{Pu}(n,f)$ cross section was subsequently determined for ${E}_{n}=0.5--7.5$ MeV. Similarly, the $(p,df$) reaction on the same two targets was used to deduce the $\ensuremath{\sigma}$$(^{237}\mathrm{Pu}(n,f))/\ensuremath{\sigma}$$(^{233}\mathrm{U}(n,f))$ ratio, and the $^{237}\mathrm{Pu}(n,f)$ cross section was extracted in the energy range ${E}_{n}=0.5--7$ MeV. The $^{238}\mathrm{Pu}(n,f)$ cross section was also deduced by utilizing the $(p,{p}^{\ensuremath{'}})$ reaction channel on the same targets. There is good agreement with the recent ENDF/B-VII.1 evaluated cross section data for $^{238}\mathrm{Pu}(n,f)$ in the range ${E}_{n}=0.5--10.5$ MeV and for $^{237}\mathrm{Pu}(n,f)$ in the range ${E}_{n}=0.5--7$ MeV; however, the $^{236}\mathrm{Pu}(n,f)$ cross section deduced in the present work is higher than the evaluation between 2 and 7 MeV.

New sideband partners of the yrast bands built on the $\ensuremath{\pi}{h}_{11/2}\ensuremath{\nu}{h}_{11/2}$ configuration were identified in ${}_{55}\mathrm{Cs}$, ${}_{57}\mathrm{La}$, and ${}_{61}\mathrm{Pm}$ $N\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}75$ isotones of ${}^{134}\mathrm{Pr}$. These bands form with ${}^{134}\mathrm{Pr}$ unique doublet-band systematics suggesting a common basis. Aplanar solutions of 3D tilted axis cranking calculations for triaxial shapes define left- and right-handed chiral systems out of the three angular momenta provided by the valence particles and the core rotation, which leads to spontaneous chiral symmetry breaking and the doublet bands. Small energy differences between the doublet bands suggest collective chiral vibrations.

The high-spin structure of {sup 205}Rn has been investigated for the first time following the {sup 170}Er({sup 40}Ar,5n) and {sup 197}Au({sup 14}N,6n) reactions at beam energies of 183 MeV and 90{endash}110 MeV, respectively, using the Jurosphere and YRAST Ball arrays. Two new cascades have been identified which dominate the high-spin decay. One of these, consisting of ten stretched M1 transitions with unobserved E2 crossover transitions, is interpreted as a shears structure based on the {nu}i{sub 13/2}{sup {minus}1}{circle_times}{pi}i{sub 13/2}{sup 2} (or {nu}i{sub 13/2}{sup {minus}1}{circle_times}{pi}h{sub 9/2}i{sub 13/2}) configuration. {copyright} {ital 1999} {ital The American Physical Society}

A high statistics experiment performed on Gd nuclei with the use of the EUROGAM II array resulted in the discovery of twelve new superdeformed (SD) bands. Three of them have been assigned to ${}^{148}\mathrm{Gd}$ and seven to ${}^{149}\mathrm{Gd}$ giving a total of thirteen SD bands now known in this last nucleus. The close relationship in transition energies between these bands and those in neighboring nuclei has been used to suggest configurations. Most of the new bands exhibit more or less pronounced irregularities in their dynamical moments of inertia with consequences on their identities with other bands.

In a recent experiment performed with the EUROGAM II {gamma}-ray spectrometer three superdeformed (SD) bands have been established in {sup 153}Ho. The properties of these bands are discussed in terms of single-particle proton excitations and are compared with respect to the SD magic nucleus {sup 152}Dy. These results represent the first observation of SD structures in a holmium nucleus and provide further information on the proton orbitals lying above the Z=66 shell gap. {copyright} {ital 1997} {ital The American Physical Society}

Odd-mass gadolinium isotopes around $N=90$ were populated by the ($p$,$d$) reaction, utilizing 25-MeV protons, resulting in population of low-spin quasineutron states at energies near and below the Fermi surface. Systematics of the single quasineutron levels populated are presented. A large excitation energy gap is observed between levels originating from the $2{d}_{3/2}$, $1{h}_{11/2}$, and $3{s}_{1/2}$ spherical parents (above the $N=64$ gap), and the $2{d}_{5/2}$ (below the gap), indicating that the spherical shell model level spacing is maintained at least to moderate deformations.

The near-yrast structure of the near-magic, odd-odd nucleus, ${}_{39}^{88}$Y${}_{49}$, has been studied into the high-spin regime. Investigations were performed at the Wright Nuclear Structure Laboratory, Yale University, using the ${}^{74}$Ge(${}^{18}$O,$p3n$) and ${}^{76}$Ge(${}^{18}$O,$p5n$) fusion-evaporation reactions at beam energies of 60 and 90 MeV, respectively. Gamma-ray energy coincidence analyses using both double (${\ensuremath{\gamma}}^{2}$) and triple (${\ensuremath{\gamma}}^{3}$) fold coincidences, together with angular correlation measurements, have been used to extend the previously reported level scheme to an excitation energy of 8.6 MeV and a spin and parity of 19${}^{(\ensuremath{-})}$. The presented level scheme is compared with predictions of a truncated valence space shell-model calculation, which assumes an inert ${}^{56}$Ni core with proton and neutron excitations allowed within the ${f}_{5/2}$, ${p}_{3/2}$, ${p}_{1/2}$, and ${g}_{9/2}$ single-particle states. The shell-model calculations show a reasonable comparison with the experimental data for the yrast, positive-parity states up to spin 18 $\ensuremath{\hbar}$, with larger variations evident for negative-parity states with spins greater than 16 $\ensuremath{\hbar}$. In spite of a significant increase in angular momentum input associated with the thin target ${}^{76}$Ge(${}^{18}$O,$p5n$) reaction channel, as compared to the backed target data using the ${}^{74}$Ge target, no additional discrete states were identified in the former data set, suggesting that the level scheme for this nucleus fragments significantly above the observed states, possibly indicating cross-shell excitations becoming dominant for $Ig$19 $\ensuremath{\hbar}$.

The goal of this communication is to propose a model of interaction of the cultures based on the concept of radiation by analogy with the quantum model of the light. Just as the light can be considered in modern physics either a flow of particles or an undulation, in the same way, to the granular dimension of the information emitted by an organization in its data flows, we will add a wave-like dimension in the form of radiation. The socio technical device of radiation is a particular form of Distic

Intruder rotational bands have been investigated to high frequency in $_{51}^{109}\mathrm{Sb}$. Five decoupled (\ensuremath{\Delta}I=2) bands extending to rotational frequencies above 1.4 MeV/\ensuremath{\Elzxh} have been observed. At the highest frequencies, the ${\mathit{J}}^{(2)}$ dynamic moments of inertia for four of these bands are seen to decrease steadily to unexpectedly low values, ${\mathit{J}}^{(2)}$ \ensuremath{\sim} 10 ${\mathrm{\ensuremath{\Elzxh}}}^{2}$ ${\mathrm{MeV}}^{\mathrm{\ensuremath{-}}1}$. These four bands, which are interpreted as being based on deformed 2p-2h proton excitations across the Z=50 closed-shell gap, achieve the so-called ``smooth band termination'' following alignment of the valence nucleons outside of $^{100}\mathrm{Sn}$. In addition, two strongly coupled (\ensuremath{\Delta}I=1) bands have been observed, which are related to 1p-1h proton excitations across the gap. \textcopyright{} 1996 The American Physical Society.

An excited superdeformed band has been observed in $^{131}\mathrm{Ce}$ consisting of 13 \ensuremath{\gamma} rays and extending to spin \ensuremath{\sim}50\ensuremath{\Elzxh}. Possible configurations are discussed in terms of particle-hole excitations in a deformed Woods-Saxon potential. \textcopyright{} 1996 The American Physical Society.

Precise level lifetimes have been measured for various superdeformed bands in Gd-148,Gd-149 and Dy-152 with the Doppler-shift attenuation method From the derived quadrupole moments, Q(0), we find large differences in deformation between the yrast bands and some excited bands in the gadolinium isotopes. Moreover, two of the excited Gd bands and the Dy-152 yrast band, which have identical moments of inertia, have different elongations, supporting the picture that alignment and deformation effects cancel in identical bands.

Superdeformed bands observed in {sup 131}Ce, {sup 132}Ce, and {sup 133}Ce have sequences of {gamma}-ray transition energies that exhibit a {Delta}{ital I}=2 staggering. This staggering has different characteristics to that seen in previously known cases in other mass regions. The energy staggering starts at low rotational frequency ({sq_bullet}{omega}=3 MeV for {sup 131}Ce) at a magnitude of {approximately}{plus_minus}0.3 keV, dies away to zero at intermediate frequency ({sq_bullet}{omega}=0.6{minus}0.7 MeV), and reappears at higher frequencies ({sq_bullet}{omega}{approximately}0.7 MeV). {copyright} {ital 1996 The American Physical Society.}

Excited states of the {sup 125}La and {sup 127}La nuclei were populated following {sup 112}Sn({sup 16}O,{ital p}2{ital n}) and {sup 112}Cd({sup 19}F,4{ital n}) fusion-evaporation reactions, respectively, and investigated using methods of in-beam {gamma}-ray spectroscopy. Five collective bands in {sup 125}La, and eleven collective bands in {sup 127}La were observed. The spin and/or parity assignments of excited states in these nuclei were based on angular-correlation and linear-polarization measurements. The experimental data are discussed and compared to the results of self-consistent total-Routhian-surface calculations including quadrupole pairing. {copyright} {ital 1996 The American Physical Society.}

Low-spin, high-excitation energy states in ${}^{88}$Y have been studied using the ${}^{89}$Y($p,d\ensuremath{\gamma}$) reaction. For this experiment a 25 MeV proton beam was incident upon a monoisotopic ${}^{89}$Y target. A silicon telescope array was used to detect deuterons, and coincident $\ensuremath{\gamma}$ rays were detected using a germanium clover array. Most of the known low-excitation-energy low-spin states populated strongly via the ($p,d$) reaction mechanism are confirmed. Two states are seen for the first time and seven new transitions, including one which bypasses the two low-lying isomeric states, are observed.

Two new superdeformed (SD) bands have been observed in Tb-150 using the reaction P-31 + Sn-124 and the GAMMASPHERE detector array. These new bands are interpreted as being excited SD configurations ...

High spin states in {sup 113}I were studied with the {sup 58}Ni({sup 58}Ni, 3{ital p}{gamma}) reaction at 240 MeV, using the EUROGAM array in Daresbury, United Kingdom, with 45 Ge detectors. A total of five deformed intruder bands extending to spins {ital I} ranging from (73/2--89/2){h_bar} have been identified, all of which reach frequencies {h_bar}{omega}{gt}1.0 MeV and excitation energies {similar_to}25 MeV. A gradual dropoff of the dynamic moment of inertia {ital scrI}{sup (2)} with increasing rotational frequency has been observed and attributed to a mode of ``soft`` band termination involving valence particle alignment. In this process, the nucleus progresses gradually, over many transitions, towards a noncollective oblate ({gamma}=+60{degree}) band terminating state.

Two excited superdeformed (SD) bands have been observed in ${}^{132}\mathrm{Ce}$ using the Eurogam gamma-ray spectrometer. Possible configurations are proposed in terms of particle-hole excitation from a theoretical analysis based on the cranking approximation with the Woods-Saxon deformed potential. From relationships between $\ensuremath{\gamma}$-ray energies of SD bands in ${}^{132}\mathrm{Ce}$ and ${}^{131}\mathrm{Ce}$, the existence of identical bands and approximately quantized alignments is established in the mass 130 region.

A novel method of selecting \ensuremath{\gamma}-ray transitions in heavy nuclei (Ag100) at the proton drip-line has been attempted. The characteristic charged-particle radioactivity of these nuclei (alpha decay, ground-state proton decay, and \ensuremath{\beta}-delayed proton emission) has been used to tag \ensuremath{\gamma}-ray transitions recorded by the highly efficient Eurogam spectrometer. The $^{58}\mathrm{Ni}$${+}^{54}$Fe and $^{58}\mathrm{Ni}$${+}^{58}$Ni fusion-evaporation reactions, at a beam energy of 240 MeV, have been used to populate specific states of these neutron-deficient nuclei and results are presented for $^{108,109}\mathrm{Te}$, $^{109}\mathrm{I}$, and $^{113}\mathrm{Xe}$, where \ensuremath{\gamma}-ray transitions have been identified. In the case of $^{109}\mathrm{I}$, this represents the first observation of \ensuremath{\gamma}-rays from a ground-state proton emitter.

Y. Oktem,1 D. L. Balabanski,2 B. Akkus,1 L. Amon Susam,1 L. Atanasova,2 C. W. Beausang,3,4 R. B. Cakirli,1,5 R. F. Casten,3 M. Danchev,6,7 M. Djongolov,6,7 E. Ganioglu,1 K. A. Gladnishki,7 J. Tm. Goon,8 D. J. Hartley,6,9 A. A. Hecht,3,10 R. Krucken,3,11 J. R. Novak,3 G. Rainovski,7 L. L. Riedinger,6 T. Venkova,2 I. Yigitoglu,12 N. V. Zamfir,3,13 and O. Zeidan6 1Department of Physics, Istanbul University, Vezneciler, 34134, Istanbul, Turkey 2Institute for Nuclear Research and Nuclear Energy, Bulgarian Academy of Sciences, BG-1784 Sofia, Bulgaria 3Wright Nuclear Structure Laboratory, Yale University, New Haven, Connecticut 06520, USA 4Department of Physics, University of Richmond, Richmond, Virginia 23173, USA 5Max-Planck-Institut fur Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg, Germany 6Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA 7Faculty of Physics, St. Kliment Ohridski University of Sofia, BG-1164 Sofia, Bulgaria 8Louisiana State University Department of Physics and Astronomy 202 Nicholson Hall, Tower Drive, Baton Rouge, Louisiana 70803-4001, USA 9Department of Physics, U.S. Naval Academy, Annapolis, Maryland 21402, USA 10Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, USA 11TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia V6T 2A3, Canada 12Gaziosmanpasa University, Science Faculty, Turkey 13National Institute for Physics and Nuclear Engineering, Bucharest-Magurele, Romania (Received 14 July 2012; published 12 November 2012)

T. J. Ross,1,2 C. W. Beausang,1 R. O. Hughes,1 J. M. Allmond,3 C. T. Angell,4,* M. S. Basunia,5 D. L. Bleuel,6 J. T. Burke,6 R. J. Casperson,6 J. E. Escher,6 P. Fallon,5 R. Hatarik,5 J. Munson,4 S. Paschalis,5,† M. Petri,5,† L. Phair,5 J. J. Ressler,6 N. D. Scielzo,6 and I. J. Thompson6 1Department of Physics, University of Richmond, Richmond, Virginia 23173, USA 2Department of Physics, University of Surrey, Guildford, Surrey, GU2 7JL, UK 3JIHIR, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA 4Department of Nuclear Engineering, University of California, Berkeley, California 94720, USA 5Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA 6Lawrence Livermore National Laboratory, Livermore, California 94551, USA (Received 17 April 2012; published 24 May 2012)

The complete spectrum of [gamma] rays following the decay of superdeformed (SD) states in [sup 192]Hg has been extracted. The spectrum, which comprises a quasicontinuous component and sharp lines, reveals the decay mechanism and defines the excitation energies of the SD band. The decay of SD states results from the coupling between a cold, ordered SD system with a hot, chaotic one with normal deformation.

An excited superdeformed (SD) band in 150 Gd is associated with a two-particle-two-hole proton excitation and provides the first evidence for collective proton pair excitations in a SD nucleus. This band is seen to exhibit a discontinuity in the γ-ray transition energies (backbending), which is interpreted as a band crossing associated with the alignment of a pair of N=6 protons. There is further evidence that this excited SD band decays into the yrast SD band.

The nuclei $^{132,134}\mathrm{Pr}$ have been investigated using the $^{100}\mathrm{Mo}$${(}^{37}$Cl,xn) reactions at a beam energy of 155 MeV. Gamma rays were detected with the Eurogam array. Analysis of the data has revealed the presence of two new weakly populated decoupled bands in $^{134}\mathrm{Pr}$. One of these bands has been linked into the normal-deformed states and is thought to be built on a \ensuremath{\pi}(${\mathit{h}}_{11/2}$${)}^{2}$\ensuremath{\bigotimes}\ensuremath{\nu}(${\mathit{f}}_{7/2}$,${\mathit{h}}_{9/2}$) configuration. The second band has been interpreted as being based on a \ensuremath{\pi}(${\mathit{h}}_{11/2}$${)}^{3}$\ensuremath{\bigotimes}\ensuremath{\nu}${\mathit{i}}_{13/2}$ intruder configuration within the second ${\mathrm{\ensuremath{\beta}}}_{2}$\ensuremath{\simeq}0.3 prolate minimum. The known decoupled band in $^{132}\mathrm{Pr}$ (5n reaction channel) and the highly deformed band in $^{130}\mathrm{La}$ A(\ensuremath{\alpha}3n) have also been extended. The structure of all of these bands is discussed together with similar bands in nieghboring odd-odd nuclei.

States in the neutron-deficient $^{110,112}\mathrm{Te}$ isotopes have been populated following $^{58}\mathrm{Ni}$${+}^{58,60}$Ni reactions. Gamma-ray coincidence data were acquired with the Eurogam spectrometer in conjunction with the Daresbury recoil separator and with the Chalk River 8\ensuremath{\pi} spectrometer. Although the low lying yrast states are not collective in these nuclei, a long regular cascade of transitions, indicating collective behavior, was found in $^{112}\mathrm{Te}$ extending to high spin. This structure is interpreted in terms of a deformed 4-particle 2-hole ${0}_{2}^{+}$ state coupled to rotationally aligned quasiparticles, and represents the first example of a rotational ``intruder'' band in the tellurium isotopes.

Two weakly populated rotational bands have been established in [sup 106]Sn from the [sup 54]Fe ([sup 58]Ni,[alpha]2[ital p]) reaction at 243 MeV. One of the bands shows evidence of termination. The result is consistent with cranked Nilsson model calculations, which predict band terminations with a smooth and gradual shape change from a prolate collective to an oblate noncollective structure.

Lifetimes of states in four of the oblate dipole bands in $^{197,198}\mathrm{Pb}$ have been measured with the recoil distance technique. Using all the available data on lifetimes and branching ratios, and assuming pure magnetic dipole transitions, we deduce transition probabilities. The results are consistent with weakly oblate collective structures involving high-K proton configurations coupled to rotationally aligned neutrons. Comparsions are made to the theoretical estimates of the D\"onau and Frauendorf semi-classical model and the tilted axis cranking (TAC) model.

The high-spin structure of [sup 139]Sm has been investigated with the [sup 110]Pd([sup 34]S,5[ital n]) reaction at a beam energy of 159 MeV at the Stony Brook Tandem/Superconducting LINAC facility. The TESSA3 spectrometer array was used to collect [gamma]-[gamma] coincidence data from which an extended decoupled band structure has been found. It is proposed that this band is based on the [ital i][sub 13/2] ([Omega]=1/2) neutron intruder orbital. The decay pattern, enhanced dynamic moments of inertia, and aligned spins are consistent with the [nu][ital i][sub 13/2] bands in neighboring odd-neutron nuclides. Total Routhian surface and cranked shell model calculations reproduce qualitative features of these nuclides, further supporting the proposed interpretation.

The neutron-induced fission cross section of {sup 238}Pu was determined using the surrogate ratio method. The (n,f) cross section over an equivalent neutron energy range 5-20 MeV was deduced from inelastic {alpha}-induced fission reactions on {sup 239}Pu, with {sup 235}U({alpha},{alpha}{sup '}f) and {sup 236}U({alpha},{alpha}{sup '}f) used as references. These reference reactions reflect {sup 234}U(n,f) and {sup 235}U(n,f) yields, respectively. The deduced {sup 238}Pu(n,f) cross section agrees well with standard data libraries up to {approx}10 MeV, although larger values are seen at higher energies. The difference at higher energies is less than 20%.

The moment of inertia of the yrast superdeformed band in [sup 149]Gd exhibits an unexpected bifurcation at high rotational frequency. States differing by four units of angular momentum show an energy shift of about 60 eV. This indicates the remnant of a new quantum number associated with the fourfold rotational symmetry.

Relative intensities of the yrast and the first excited superdeformed bands in $^{151}\mathrm{Tb}$ have been accurately measured, with the EUROGAM spectrometer. It is shown that he excited band depopulates at the same freqeuncy and spin as its identical band in the isotone $^{152}\mathrm{Dy}$ whereas the yrast band deexcites at higher rotational frequency and spin even though it is much lower in excitation energy. A classification of superdeformed bands in the A\ensuremath{\sim}150 mass region indicates that the decay-out mechanism is strongly affected by neutron pairing correlations and the occupancy of high-N intruder orbitals.

Dipole transitions linking signature partner superdeformed bands in 193Hg have been observed. Measurements of the photon decay branching ratios, taken together with the average superdeformed quadrupole moment measured in neighboring nuclei, enable the absolute M1 strengths to be determined. From these data, using the strong coupling model, we find (gK-gR)K/Q0=-0.14±0.01 (e b)−1, gK=-0.65±0.14 with Ω=2.8±0.8. These data are consistent with the superdeformed neutron orbital being [512]5/2− as predicted by cranked Woods-Saxon calculations.

High-spin states in the neutron-deficient 113I nucleus have been investigated for the first time using the 58Ni(58Ni,3pγ) reaction. Gamma-ray coincidence data were acquired with the Eurogam spectrometer in conjunction with the Daresbury recoil mass separator. A deformed intruder band has been established extending to a spin approaching 40ħ and excitation energy 30 MeV. A possible structure for the band is discussed. This is the first evidence for such a band in this mass region with Z>51.

The nucleus $^{193}\mathrm{Hg}$ was populated in the reaction $^{176}\mathrm{Yb}$${(}^{22}$Ne,5n) at the incident energy E${(}^{22}$Ne)=110 MeV. Reaction \ensuremath{\gamma} rays were detected with a Ge-detector array. A new ``collective'' structure was observed at ${\mathit{E}}_{\mathit{x}}$g5.7 MeV. The states of the structure extend from I\ensuremath{\ge}47/2 to I+10, and they decay with competing dipole and quadrupole transitions. The structure is populated very strongly in this reaction: the lowest member is produced with \ensuremath{\sim}20% of the $^{193}\mathrm{Hg}$ cross section.

The transition from strong static pairing to weak static pairing and its consequences to the excitation spectrum of a mesoscopic (medium number of particles) system are investigated. New levels have been measured in $^{168}\mathrm{Yb}$. A reasonable description of the A\ensuremath{\approxeq}168 isotopes spectra is obtained. The adequacy of the phase transition concept is discussed.

The surrogate nuclear reaction method can be used to determine neutron-induced reaction cross sections from measured decay properties of a compound nucleus created using a different reaction and calculated formation cross sections. The reliability of $(n,\ensuremath{\gamma})$ cross sections determined using the Weisskopf-Ewing and ratio approximations are explored for the $^{155,157}\mathrm{Gd}$$(n,\ensuremath{\gamma})$ reactions. Enriched gadolinium targets were bombarded with 22-MeV protons and $\ensuremath{\gamma}$ rays were detected in coincidence with scattered protons using the Silicon Telescope Array for Reaction Studies/Livermore-Berkeley Array for Collaborative Experiments (STARS/LiBerACE) silicon and germanium detector arrays. The $\ensuremath{\gamma}$-emission probabilities for the $^{154,156,158}\mathrm{Gd}$ compound nuclei were measured at excitation energies up to 12 MeV. It is found that the approximations yield results that deviate from directly measured $^{155,157}\mathrm{Gd}$$(n,\ensuremath{\gamma})$ cross sections at low energies. To extract reliable cross sections, a more sophisticated analysis should be developed that takes into account angular-momentum differences between the neutron-induced and surrogate reactions.

Short-lived isomers in fission fragments following bombardment of 45-MeV {sup 6}Li on {sup 232}Th were examined. Isomers in the A{approx}95, 122, and 132 mass regions were observed. New isomeric decays were observed in {sup 121}In[T{sub 1/2}=17(2) mus], {sup 123}In (T{sub 1/2}> or approx.100 mus), and {sup 125}Sb[T{sub 1/2}=25(4) mus]. These isomers are suggested to arise from nu(h{sub 11/2} x d{sub 3/2})7{sup -} and nu(h{sub 11/2} x s{sub 1/2})5{sup -} neutron core excitations coupling with the valence proton.

The {sup 154}Sm({sup 30}Si,5{ital n}){sup 179}Os reaction has been used to study rotational bands at high spin by means of extensive gamma-ray coincidence measurements. The new {alpha}={minus}1/2 signature partner of the 1/2{sup {minus}}(521) band has been found up to spin 31/2{sup {minus}} and the previously known {alpha}=+1/2 partner extended up to spin 45/2{sup {minus}}. The {alpha}={minus}1/2 and {alpha}=+1/2 components of the previously known 7/2{sup {minus}}(514) and the 9/2{sup +}(624) bands were extended up to spins 63/2{sup {minus}}, 53/2{sup {minus}} and 63/2{sup +},61/2{sup +}, respectively. The two components of the newly found band 5/2{sup {minus}}(512) have been established up to spins 59/2{sup {minus}} and 65/2{sup {minus}}. In addition, two other new bands were found, one of them with spins up to 61/2{sup +} decays to the 9/2{sup +}(624) band. Configurations have been proposed by comparing the signature splittings and the {ital B}({ital M}1)/{ital B}({ital E}2) ratios with the theoretical predictions. The latter points to rather strong Coriolis interaction between the 5/2{sup {minus}}(512) and 7/2{sup {minus}}(514) bands. The first band crossing observed in nine out of the ten bands is most probably due to the alignment of a pair of {ital i}{sub 13/2} neutrons, on the basis of a comparison of experimentalmore » Routhians with the cranking shell model calculations. In the three positive-parity sequences and in the {alpha}=+1/2 signature of the 5/2{sup {minus}}(512) band, second band crossings are also observed that are suggested to be caused by an alignment of two {ital h}{sub 9/2} protons.« less