Search

High spin states in 161Er and 162Er have been populated using the 130Te+36S reaction at a 36S bombarding energy of 170 MeV. In 161Er, three rotational bands were extended from I approximately=35 h(cross) to I approximately=50 h(cross). In 162Er the lowest energy positive parity band was observed to I=44 h(cross) and two negative parity bands to I approximately=32 h(cross). The behaviour of these rotational sequences are explained in terms of the expected spectrum of single neutron states in the absence of static neutron pair correlations.

A Gammasphere experiment was carried out to search for triaxial strongly deformed (TSD) structures in $^{171,172}\mathrm{Hf}$ and the wobbling mode, a unique signature of nuclei with stable triaxiality. Three strongly deformed bands in $^{172}\mathrm{Hf}$ and one in $^{171}\mathrm{Hf}$ were identified through $^{48}\mathrm{Ca}$($^{128}\mathrm{Te}$, xn) reactions. Linking transitions were established for the band in $^{171}\mathrm{Hf}$ and, consequently, its excitation energies and spins (up to $111/2\ensuremath{\hbar}$) were firmly established. However, none of the $^{172}\mathrm{Hf}$ sequences were linked to known structures. Experimental evidence of triaxiality was not observed in these bands. The new bands are compared with other known strongly deformed bands in neighboring Hf isotopes. Theoretical investigations within various models have been performed. Cranking calculations with the Ultimate Cranker code suggest that the band in $^{171}\mathrm{Hf}$ and two previously proposed TSD candidates in $^{170}\mathrm{Hf}$ and $^{175}\mathrm{Hf}$ are built on proton $({i}_{13/2}{h}_{9/2})$ configurations, associated with near-prolate shapes and deformations enhanced with respect to the normal deformed bands. Cranked relativistic mean-field calculations suggest that band 2 in $^{175}\mathrm{Hf}$ has most likely a near-prolate superdeformed shape involving the $\ensuremath{\pi}{i}_{13/2}\ensuremath{\bigotimes}\ensuremath{\nu}{j}_{15/2}$ high-$j$ intruder orbitals. It is quite likely that the bands in $^{172}\mathrm{Hf}$ are similar in character to this band.

Intramuscular injection of Botulinum toxin to produce reduction of focal muscle overactivity, and localized muscle spasm, has been utilized therapeutically for almost two decades. Muscle overactivity in neurologically normal muscle, where an imbalance exists between a relatively overactive muscle and its less active synergist or antagonist, can inhibit control of the antagonist producing a functional muscle imbalance. This brief review provides an overview of the role of muscle imbalance in sports-related pain and dysfunction, and outlines the potential for intramuscular injection of Botulinum toxin to be used as an adjunct to specific muscle re-education and functional rehabilitation in this patient group. A comprehensive understanding of normal movement and the requirements of the sporting activity are essential to allow accurate diagnosis of abnormal motor patterns and to re-educate more appropriate movement strategies. Therapeutic management of co-impairments may include stretching of tight soft tissues, specific re-education aimed at isolation of the non-dominant weak muscles and improvement in their activation, 'unlearning' of faulty motor patterns, and eventual progression onto functional exercises to anticipate gradual return to sporting activity. Intramuscular injection of Botulinum toxin, in carefully selected cases, provides short term reduction of focal muscle overactivity, and may facilitate activation of relatively 'inhibited' muscles and assist the restoration of more appropriate motor patterns.

High-spin states in neutron-rich Hf-180 and Hf-182 nuclei were populated through inelastic and transfer reactions with a Xe-136 beam incident on a thin Hf-180 target, and investigated using particle-gamma coincidence techniques. New collective band structures were observed, and previously known rotational and vibrational bands in these nuclei were extended to higher angular momenta. No obvious nucleon alignment was observed in the ground state band of either nucleus up to h omega=0.43 MeV, a significant delay compared to lighter even-even Hf isotopes. Woods-Saxon cranking calculations were performed to predict the nature of the first band crossings and shape evolution in Hf-180,Hf-182.

This report details the status of an experimental research programme which has studied isomeric states in the mass 130–160 region of the nuclear chart. Several new isomers have been established and characterised near the proton drip line using a recoil isomer tagging technique at the University of Jyvaskyla, Finland. The latest experiments have been performed with a modified setup where the standard GREAT focal‐plane double‐sided silicon‐strip detector was changed to a dual multi‐wire proportional‐counter arrangement. This new setup has improved capability for short‐lived isomer studies where high focal‐plane rates can be tolerated. The results of key recent experiments for nuclei situated above (153Yb,152Tm) and below (136Pm,142Tb) the N = 82 shell gap were presented along with an interpretation for the isomers. Finally, the future prospects of the technique, using an isomer‐tagged differential‐plunger setup, were discussed. This technique will be capable of establishing the deformation of the states abo...

The new neutron-deficient isotopes Rn-193,Rn-194 have been identified in the complete fusion reaction Cr-52+Sm-144 -> Rn-196(*) at the velocity filter SHIP. The alpha-decay energy and half-life value of Rn-194 were determined to be E-alpha=7700(10) keV and T-1/2=0.78(16) ms, respectively. For Rn-193 the half-life of T-1/2=1.15(27) ms and two alpha lines at E-alpha 1=7685(15) keV, I-alpha 1=74(20)% and E-alpha 2=7875(20) keV, I-alpha 2=26(12)% were found. The decay pattern of Rn-193, which is substantially different from that of the heavier odd-A Rn isotopes, provides first experimental evidence for the long-predicted deformation in the very neutron-deficient Rn nuclei.

An extended decay scheme for Xe-128 has been constructed by using data from the Sn-124(Be-9, 5n)Xe-128 reaction at a beam energy of 58 MeV. Bands have been identified as being built on several intrinsic states, including a proposed 9/2(-)[514] circle times 1/2(+)[400] two-quasineutron configuration that forms the K-pi=5(-) intrinsic state at 2228 keV, and on a previously assigned K-pi=8(-) intrinsic state at 2786 keV. A half-life of 73(3) ns has been measured for the latter. Theoretical calculations have been performed by using the configuration-constrained blocking method based on a nonaxial Woods-Saxon potential. Large gamma deformation and gamma softness are predicted for the ground state and the K-pi=5(-) intrinsic state, whereas a nearly axially symmetric shape is predicted for the K-pi=8(-) two-quasiparticle configuration. The low value of the hindrance factor for the E1 transition depopulating the K-pi=8(-) intrinsic state is discussed in the context of analogous transitions in neighbouring N=74 isotones.

Jolie, J. Ilie, G. Reiter, P. Richard, A. Scherillo, A. Striepling, T. Warr, N. Banu, A. Becker, F. Bednarczyk, P. Doornenbal, P. Gerl, J. Grawe, H. Gorska, M. Kojouharov, I. Mandal, S. Saito, N. Saito, T. R. Wollersheim, H. -J. Mallion, S. Neyens, G. Turzo, K. Van Duppen, P. Vermeulen, N. Podolyak, Zs. Gelletly, W. Regan, P. H. Walker, P. M. Catford, W. N. Liu, Z. Williams, S. Blazhev, A. Lozeva, R. Detistov, P. Atanasova, L. Damyanova, G. Gil, D. Cortina Benlliure, J. Kurtukian Nieto, T. Caserejos, E. Daugas, J. M. Belier, G. Meot, V. Roig, O. Simpson, G. Tsekhanovich, I. S. Matea, I. Schwengner, R. Hass, M. Singh, B. S. Nara Chamoli, S. K. Goldring, G. Regev, I. Vaintraub, S. Balabanski, D. L. Lo Bianco, G. Gladnishki, K. Saltarelli, A. Petrache, C. Benzoni, G. Blasi, N. Bracco, A. Camera, F. Million, B. Leoni, S. Wieland, O. Maj, A. Kmiecik, M. Grebosz, J. Bednarczyk, P. Styczen, J. Lach, M. Meczynski, W. Mazurek, K. Pfutzner, M. Korgul, A. Ionescu-Bujor, M. Iordachescu, A. Zamfir, V. Jungclaus, A. Georgiev, G. Cullen, D. M. Freeman, S. J. Smith, A. G. Orlandi, R. Clark, R. M. Bentley, M. A. Hammond, G. Wadsworth, R. Buerger, A. Huebel, H. Rudolph, D. Fahlander, C. Simpson, J. Herzberg, R. D. Page, R. D. Nolan, P. Davidson, T. Woods, P. Bruce, A. M. Faestermann, T. Kruecken, R. Mach, H. Rubio, B. Algora, A.

This paper reviews the past, present and future status of recoil‐isomer tagging at the University of Jyvaskyla. The main focus of this research has been to access isomeric states at and beyond the mass ≈140 proton drip line. Recoil‐isomer tagging was first used at the University of Jyvaskyla in 1998 to establish the prompt rotational band built upon a Kπ = 8− isomeric state in 138Gd. Since that time a series of experiments have been performed which have studied isomeric states in the N = 77 isotones 63140Eu77, 65142Tb77 and 67144Ho77, and in the N = 74 K‐isomer chain, 64138Gd74 and 66140Dy74. These experiments have revealed valuable first information about deformations, single‐particle excitation energies and hindrance factors in nuclei at and beyond the proton drip line where little or no information previously existed.The results of the most‐recent experiments were discussed. These experiments established new isomeric states in 66143Dy77, 61136Pm75, and 64137Gd73 and a further two isomers which are curr...

The characterization of a pixellated CdZnTe detector will be discussed in the context of the development of a portable gamma-ray spectrometer device. The device will utilize the spectroscopic properties of CdZnTe to provide both isotopic identification and directional information. The CdZnTe sensors will be configured for use as a Compton camera, maximizing the efficiency for both spectroscopy and imaging of the source being assayed. In order to achieve this, pulse shape analysis algorithms are being developed to accurately determine the position of the interaction of a gamma-ray photon within the detector. A pixellated CdZnTe detector has been scanned by moving a highly collimated source in controlled steps across the surface of the detector and taking data for a set period of time at each position. In this work, a 57Co source has been used with a 1 mm tungsten injection collimator moved in 1 mm steps across the front face and side surfaces of the detector. The results from the preparatory work and the initial scans of the detector are discussed in this work.

Significant extensions to the high-spin excitation spectrum of the N = 91, 92, 93 isotopes Dy-157,Dy-158,Dy-159 have been achieved using the high-efficiency gamma-ray spectrometers Euroball and Gammasphere. These nuclei were populated via weak 3n or alpha xn exit channels in fusion evaporation reactions. In Dy-157, the yrast band has been extended to I-pi = (2)/(101+) (tentatively to (2)/(105+)) with four sideband structures (two of which are new) observed in the 35-50h spin range. In Dy-158, three bands have been extended to 42(+)(44(+)),40(-), and 41(-)(43(-)), whereas in Dy-159 the yrast band is observed to (2)/(81+) ((2)/(85+)). The high-spin behavior and band crossing systematics of the Dy isotopes and of the neighboring N = 91, 92, and 93 isotones are discussed in terms of rotational alignments and shape transitions. Cranked Nilsson-Strutinsky calculations without pairing have been performed for detailed comparisons with the very high-spin states observed in Dy-157.

The recent experimental observation of collective rotational bands up to I > 60h in Hf-175 presents theoretical challenges. It is shown here that total Routhian surface calculations are able to explain the yrast high-spin behavior, with collective oblate states favored at I similar to 35h and strongly deformed prolate states at the highest spins. The collective oblate rotation terminates in noncollective prolate states. Comparisons are made with ultimate cranker calculations, and theoretical quadrupole moments are evaluated.

The objective of this investigation was to assess the effects of chronic nicotine administration on bone status and serum calcium and calciotropic hormone levels in aged, estrogen-replete (intact, sham-operated) and estrogen-deplete (ovariectomized) female rats. Eight-month-old sham-operated (sham) and ovariectomized (ovx) retired breeder rats were maintained untreated for 3 months to allow for the development of osteopenia in the ovx group. The animals were then administered either saline, low dose nicotine (6.0 mg/kg/day), or high dose nicotine (9.0 mg/kg/day) via osmotic minipumps for 3 months. Blood was drawn at necropsy for determination of serum nicotine, cotinine, Ca, PTH, 25(OH)D, and 1,25(OH)(2)D. Right tibiae were collected and processed undecalcified for cancellous and cortical bone histomorphometry. Histomorphometric endpoints evaluated at the proximal tibial metaphysis included cancellous bone volume (BV/TV), osteoclast surface (Oc.S), osteoid surface (OS), mineralizing surface (MS), mineral apposition rate (MAR), and bone formation rate (BFR). Histomorphometric endpoints evaluated at the tibial diaphysis included cortical area (Ct.Ar), marrow area (Ma.Ar), and periosteal and endocortical MS, MAR, and BFR. Ovariectomy resulted in lower cancellous BV/TV and Ct.Ar and higher cancellous, endocortical, and periosteal MS and BFR. The presence of nicotine in serum confirmed successful delivery of the drug via osmotic minipumps. Administration of nicotine at the high dose resulted in lower serum 25(OH)D levels but differences in serum Ca or PTH were not detected with either nicotine treatment. Differences with nicotine treatment were also not detected for Oc.S at the proximal tibia. While treatment with nicotine at the high dose resulted in higher MS and BFR, in both sham and ovx rats, there were no differences due to nicotine treatment in cancellous BV/TV. Marrow area was greater in rats treated with nicotine than in rats treated with vehicle. However, differences with nicotine treatment were not detected in Ct.Ar in either intact or ovx rats. Overall, these findings indicate that steady state nicotine exposure does not alter bone mass in intact or ovx rats but may have detrimental effects on body storage of vitamin D.

Lifetimes of excited states have been measured for the positive-parity rotational bands in neutron-rich Ba-142,Ba-144 as well as the 7(-) and 9(-) states of the negative-parity band in Ba-144 using the differential Doppler shift method. The deduced quadrupole moment, Q(t), of the positive-parity band decreases with angular momentum and overall shows good agreement with earlier measurements. The measured lifetimes of 7(-) and 9(-) states are used to determine the electric dipole moment, D-0=0.17(3) and 0.09(1) e fm, respectively, in the negative-parity octupole band of Ba-144.

Two Gammasphere experiments have been performed in order to establish the possible triaxial nature of strongly deformed (SD) bands in 174Hf. A lifetime measurement confirmed the large deformation of the four previously observed bands in this nucleus. In addition, a thin‐target, high‐statistics experiment was carried out to search for linking transitions between the SD bands. No such transitions, which represent an experimental signature for wobbling modes, were observed. Four new SD bands were found in 174Hf together with a single SD band in 173Hf. These results indicate that the strongly deformed sequences of N ≈ 102 Hf isotopes behave differently than the TSD bands found in Lu nuclei near N = 92. The interpretation of these bands in terms of possible stable triaxial deformation is confronted with the experimental findings and UC predictions.

Relativistic projectile fragmentation of Pb-208 has been used to produce isomers in neutron-rich, A approximate to 190 nuclides. A forward-focusing spectrometer provided ion-by-ion mass and charge identification. The detection of gamma-rays emitted by stopped ions has led to the assignment of isomers in Ta-188, W-190, Re-192, Re-193, Os-195, Ir-197, Ir-198, Pt-200, Pt-201, Pt-202 and Au-203, with half-lives ranging from approximately 10 ns to 1 ms. Tentative isomer information has been found also for Er-174, Er-175, Hf-185, Re-191, Re-194 and Ir-199. In most cases, time-correlated, singles gamma-ray events provided the first spectroscopic data on excited states for each nuclide. In Pt-200 and Pt-201. the assignments are supported by gamma-gamma coincidences. Isomeric ratios provide additional information, such as half-life and transition energy constraints in particular cases. The level structures of the platinum isotopes are discussed, and comparisons are made with isomer systematics.

This study assessed mouse strain-related differences in vertebral biomechanics and histomorphometry in inbred mice strains shown to differ in bone mineral content (BMC) and areal density (BMD) (as measured by pDEXA). Lumbar vertebrae L3 to L5 were collected from three mice strains (C3H/HeJ[C3], C57BL/6J[B6], and DBA/2J[D2], n=12/strain, 4-month-old female, 22.2 +/- 0.3g). BMC and BMD were measured in L3 and L4 using peripheral dual energy x-ray absorptiometry. The L4 vertebral body was then mechanically tested in compression to determine structural properties (ultimate/yield load, stiffness) from load-displacement curves and derive apparent material properties (ultimate/yield stress, and modulus of elasticity). L5 was processed for histomorphometric evaluation. Vertebral BMC and BMD were greater in C3 than in B6 and D2 mice. Vertebral trabecular/cancellous bone volume was smaller in C3 than in D2 and B6 mice. Trabecular bone formation rates were greater in D2 than in B6 and C3 mice. Osteoid surface was smaller in C3 mice than in B6 and D2 mice. Differences in osteoclast and mineralizing surfaces were not detected among the three mouse strains. In addition, there were no significant differences in biomechanical properties between the three strains. Despite the greatest BMC and areal BMD in C3 mice, the lack of strain-related differences in vertebral body strength data suggests that the biomechanical properties may be affected by the bone distribution and/or complex combination of cortical and cancellous bone at this site.

Nuclei in the $A\ensuremath{\sim}180$ region have been populated and investigated in a series of multinucleon transfer and deep-inelastic reactions involving an $11.4\phantom{\rule{0.3em}{0ex}}\text{MeV}$ per nucleon $^{136}\mathrm{Xe}$ beam produced by the GSI UNILAC accelerator, impinging on a selection of tantalum and tungsten targets. The reaction products were released from a thermal ion source and subsequently mass selected using the GSI on-line mass separator. The unexpectedly high yield of $\ensuremath{\gamma}$ rays associated with the decay of the well established ${K}^{\ensuremath{\pi}}=37∕{2}^{\ensuremath{-}}$,${t}_{1∕2}=51.4\phantom{\rule{0.3em}{0ex}}\mathrm{min}$ isomer in $_{\phantom{\rule{0.3em}{0ex}}72}^{177}\mathrm{Hf}$ and anomalous half-life characteristics associated with this decay lead to these data being interpreted as the ${\ensuremath{\beta}}^{\ensuremath{-}}$ decay of a high-$K$ isomer in the mother nucleus, $^{177}\mathrm{Lu}$. By comparing the experimental findings with the predictions obtained from multi-quasiparticle blocked-BCS-Nilsson calculations, the proposed decay is suggested to be from a ${K}^{\ensuremath{\pi}}=39∕{2}^{\ensuremath{-}}$ five-quasiparticle state in $_{\phantom{\rule{0.3em}{0ex}}71}^{177}\mathrm{Lu}$. A half-life of $7\ifmmode\pm\else\textpm\fi{}2\phantom{\rule{0.3em}{0ex}}\mathrm{min}$ is determined for this $\ensuremath{\beta}$-decay path which is estimated to have an excitation energy of $\ensuremath{\approx}3.9\phantom{\rule{0.3em}{0ex}}\text{MeV}$ above the $^{177}\mathrm{Lu}$ ground state.

We report the results of an experiment, realized with the EUROBALL IV spectrometer, in which superdeformed (SD) states have been populated in 197,198Pb nuclei. Crosstalk transitions between two signature partner SD bands in 197Pb have been observed with an established M1 character, giving access to the magnetic properties of the $\nu$ [752]5/2 intruder orbital. Six new SD bands have been identified in 197,198Pb. The results are interpreted in the framework of cranked Hartree-Fock calculations. A mixing between quasi-particle excitations and an octupole vibration is suggested in the two SD isotopes.

Two high-spin regularly spaced rotational bands with large dynamical moments of inertia have been identified in Hf-175 with the Gammasphere spectrometer. These new bands are very similar to the previously identified triaxial superdeformed bands in the hafnium nuclei. However, the new bands in Hf-175 have been linked into the known level scheme and thereby provide the first firm spin assignments for these structures in this region. In order to understand the new bands, theoretical calculations have been performed based on the ULTIMATE CRANKER code. The new bands in Hf-175 are deduced to be built upon highly deformed structures. No experimental evidence for triaxiality was established and this work suggests that the structure of the so-called "triaxial" superdeformed bands in the Hf nuclei may be quite different from those identified in the lighter mass Lu nuclei. Since the two highly deformed bands in Hf-175 are associated with different deformations, this work also identifies the role of the intruder orbits in polarizing the nuclear shape.

Evidence is presented for multiphonon excitations based on a high-spin (25 Planck) intrinsic state in the deformed nucleus 182 Os. Angular momentum generation by this mode competes with collective rotation. The experimental data are compared with tilted-axis cranking calculations, supporting the vibrational interpretation. However, the lower experimental energies provide evidence that more complex interactions of states are playing a role.

Excited states in the neutron-deficient nucleus Re-167 have been observed in a recoil-tagging experiment performed with the Jurosphere gamma-ray spectrometer in conjunction with the RITU gas-filled ...

Techniques have been developed to study isomeric states in nuclei with the use of RITU (gas filled separator) at the University of Jyvaskyla. The first was the recoil-isomer tagging technique initially, utilised by D.M. Cullen to study the K π = 8− isomeric state in 138Gd [1]. The juro-sphere array was employed in conjunction with ritu and a focal plane array which consisted of several Compton-suppressed Germanium detectors, placed in close geometry around a multi wire proportional counter (mwpc) and a silicon strip detector used for the implantation of recoiling nuclei. This technique correlates prompt and delayed γ-ray transitions across isomeric states and identifies the lifetime of the isomer. The main constraint of this technique is the timing electronics. Only isomers with a half-life greater than the flight time through RITU(~ 300ns) and less than the collection time of the tdc’s (32 μs) can be identified. This time range and hence technique is ideal for the region of mass A = 140 near proton drip line nuclei which have small production cross-sections in comparison to their more neutron rich neighbours and lack charged particle emission suitable for recoil-decay-tagging. Subsequent experiments to ref.

High‐spin states have been studied in the octupole‐deformed 222Th nucleus using the 208Pb(18O,4n) reaction. De‐excitation gamma rays were detected using the Euroball‐IV gamma‐ray spectrometer. The large background of gamma rays from prompt fission fragments, which generally hampers the spectroscopy of actinide nuclei in fusion‐evaporation reactions, has been reduced using the Euroball‐IV inner BGO ball as a sum‐energy filter. With the requirement that the summed gamma‐ray energy detected in the reaction is less than 10 MeV, the intensity of 222Th gamma‐rays, relative to the prompt fission background is significantly improved. The experiment and data analysis are discussed, and preliminary spectroscopic results are presented.

Extended abstract of a paper presented at Microscopy and Microanalysis 2012 in Phoenix, Arizona, USA, July 29 – August 2, 2012.

Excited states in the neutron-deficient isotope Os-169 have been identified for the first time in an experiment using the Jurosphere gamma-ray spectrometer in conjunction with the Ritu gas-filled r ...

The $N=86,87$ isotopes of dysprosium and holmium have been investigated using the Eurogam II $\ensuremath{\gamma}$-ray spectrometer. A new collective rotational band has been observed in ${}^{153}\mathrm{Ho}$ and the previously observed $\ensuremath{\nu}{\mathrm{i}}_{13/2}$ band in ${}^{153}\mathrm{Dy}$ has been extended to much higher spin. Comparing these bands and similar bands in ${}^{152}\mathrm{Dy}$ with the collective bands in the $N=90$ isotopes of Dy, Ho, and Er suggests that the first ${h}_{11/2}$ proton crossing is not observed at $N=86,87.$ This observation has led to the reinterpretation of four of the previously observed bands in ${}^{152}\mathrm{Dy}.$ It is proposed that the low deformation collective bands in ${}^{152,153}\mathrm{Dy}$ and ${}^{153}\mathrm{Ho}$ are associated with a triaxial shape with large positive gamma and that they have a similar origin to the recently observed triaxial superdeformed bands in ${}^{163--165}\mathrm{Lu}.$

The 36Ar + 107Ag fusion-evapn. reaction was used to search for isomeric states in the N = 77 isotope 140Eu near the proton-drip line. The recoiling nuclei were implanted into a Si detector, at the focal plane of a gas-filled separator, where prompt and delayed g-ray transitions were correlated across isomeric states using recoil-isomer tagging. The feeding and decay of a new 299(3) ns isomeric state was established. This measurement represents the first observation of excited high-spin states in 140Eu. The behavior of the new states above the isomer is discussed in terms of theor. calcns. based upon the cranked-shell model and upon the exptl. systematics of other N = 77 isotones. Within this framework, the isomer was interpreted to be built upon a ph11/2 ? nh11/2 two-quasiparticle configuration. [on SciFinder (R)]

Evidence is presented for multiphonon excitations based on a high-spin (25 Planck) intrinsic state in the deformed nucleus 182 Os. Angular momentum generation by this mode competes with collective rotation. The experimental data are compared with tilted-axis cranking calculations, supporting the vibrational interpretation. However, the lower experimental energies provide evidence that more complex interactions of states are playing a role.

A systematic study of the population probabilities of microsecond isomers produced following the fragmentation of 208Pb projectiles at 1 GeV/nucleon has been undertaken at the SIS/FRS facility at GSI Darmstadt. Gamma decays from approximately 20 isomeric states, mainly in the rare-earth and transitional nuclei with A∼180, were identified and the corresponding isomeric ratios deduced. The results are compared with a model based on the statistical abrasion-ablation description of relativistic fragmentation and simple assumptions concerning gamma cascades in the final nucleus (sharp cutoff). The model is found to represent an upper limit for the population of isomeric states in relativistic projectile fragmentation.

The neutron-rich ${}^{66,68}\mathrm{Ni}$ have been produced at GANIL via interactions of a $65.9A\mathrm{MeV}$ ${}^{70}\mathrm{Zn}$ beam with a ${}^{58}\mathrm{Ni}$ target. Their reduced transition probability $B({E2;0}_{1}^{+}\ensuremath{\rightarrow}{2}^{+})$ has been measured for the first time by Coulomb excitation in a ${}^{208}\mathrm{Pb}$ target at intermediate energy. The $B(E2)$ value for ${}^{68}{\mathrm{Ni}}_{40}$ is unexpectedly small. An analysis in terms of large scale shell model calculations stresses the importance of proton core excitations to reproduce the $B(E2)$ values and indicates the erosion of the $N\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}40$ harmonic-oscillator subshell by neutron-pair scattering.

Deep-inelastic collisions of 136Xe ions with tantalum and tungsten targets have been used to study high-spin isomers in neutron-rich A≈180 nuclei at the GSI on-line mass separator. Gamma-rays associated with the decay of the well known Kπ=37/2−, 51-minute isomer in 177Hf were observed, but with different half-life characteristics and an unexpectedly high yield. These features are interpreted as evidence for a hitherto unrecognized isomer in 177Lu. A two-component half-life analysis of the 177Hf γ-ray intensities gives a first component of 6−2+3 min, when the second component is fixed at 51 min. Comparison with multi-quasiparticle calculations suggests the possibility of a Kπ=39/2− isomer in 177Lu, which β-decays to the 177Hf isomer. This would be the highest-spin β-decaying state yet identified.

New high-K orbitals have been identified in the neutron-rich {sup 181}Hf nucleus via one-neutron transfer from a pulsed {sup 238}U beam onto a stable {sup 180}Hf target. Yrast three-quasiparticle high-K isomers, with half-lives as long as 1.5 ms, have been populated. The decay scheme of {sup 181}Hf has been extended to (25/2{sup -}). Blocked BCS calculations, including residual interactions, compare well with the experimental results.

The ${\ensuremath{\beta}}^{+}$-decay half-lives of the neutron-deficient odd-odd $N=Z$ nuclei ${}^{74}\mathrm{Rb},$ ${}^{78}\mathrm{Y},$ ${}^{82}\mathrm{Nb},$ and ${}^{86}\mathrm{Tc}$ have been measured following the fragmentation of a primary ${}^{92}\mathrm{Mo}$ beam at an energy of 60 MeV per nucleon at the GANIL laboratory, France. This was achieved by correlating ${\ensuremath{\beta}}^{+}$ decays with the implantation of unambiguously identified fragments at the final focus of the LISE3 separator. The deduced ${\mathrm{log}}_{10}{\mathrm{ft}}_{1/2}$ values are consistent with ${0}^{+}\ensuremath{\rightarrow}{0}^{+},$ Fermi superallowed transitions, which together with the measured ${\ensuremath{\beta}}^{+}$-detection efficiencies, suggest $T=1,$ ${I}^{\ensuremath{\pi}}{=0}^{+}$ ground states for these odd-odd $N=Z$ nuclei. These data represent the heaviest $N=Z$ systems for which Fermi superallowed decays have been established.

The next generation of 4 pi arrays for high-precision gamma -ray spectroscopy will involve "gamma -ray tracking front-end on digital signal processing techniques, which allows to extract energy, timing and spatial information on the interactions of a gamma -ray in the Ge detector by pulse shape analysis of its signals. Utilizing the information on the positions of the interaction points and the energies released at each point the tracks of the gamma -rays in a Ge shell can be reconstructed in three dimensions.

The neutron-rich (66,68)Ni have been produced at GANIL via interactions of a 65.9A MeV 70Zn beam with a 58Ni target. Their reduced transition probability B(E2;0(+)(1)--2+) has been measured for the first time by Coulomb excitation in a (208)Pb target at intermediate energy. The B(E2) value for (68)Ni(40) is unexpectedly small. An analysis in terms of large scale shell model calculations stresses the importance of proton core excitations to reproduce the B(E2) values and indicates the erosion of the N = 40 harmonic-oscillator subshell by neutron-pair scattering.

For the first time, six-quasiparticle isomers have been observed in the meta-stable nucleus ${}_{ 73}^{180}{\mathrm{Ta}}_{107}.$ Two new high-spin isomers were populated following deep-inelastic reactions with a pulsed ${}_{ 92}^{238}\mathrm{U}$ beam incident on a thick ${}_{ 72}^{180}\mathrm{Hf}$ target. Out-of-beam $\ensuremath{\gamma}$-ray events were collected using the Gammasphere germanium detector array. In addition to the known four-quasiparticle isomers, yrast ${K}^{\ensuremath{\pi}}{=(22}^{\ensuremath{-}})$ and $Kg~23$ six-quasiparticle isomers have been observed with microsecond half-lives. These are the highest-spin isomers observed using the technique of deep-inelastic excitation. The assignments are compared to predictions made by BCS and Lipkin-Nogami multiquasiparticle calculations.

Very high spin states $(I=50--60\ensuremath{\Elzxh})$ have been observed in the transitional nuclei ${}^{161}\mathrm{Er}$ and ${}^{162}\mathrm{Er}$ using the Euroball $\ensuremath{\gamma}$-ray spectrometer. In ${}^{161}\mathrm{Er},$ three bands are observed well above spin $50\ensuremath{\Elzxh}.$ In the positive parity, positive signature $(+,+\frac{1}{2})$ band a discontinuity in the regular rotational behavior occurs at ${\frac{109}{2}}^{+}$ and a splitting into two branches occurs at ${\frac{97}{2}}^{\ensuremath{-}}$ in the negative parity, positive signature $(\ensuremath{-},+\frac{1}{2})$ band. The $(\ensuremath{-},\ensuremath{-}\frac{1}{2})$ band continues in a regular fashion to ${\frac{115}{2}}^{\ensuremath{-}},$ tentatively $({\frac{119}{2}}^{\ensuremath{-}}).$ In ${}^{162}\mathrm{Er}$ the positive parity, even spin (+,0) yrast band is observed to continue smoothly up to ${58}^{+}$ ${(60}^{+})$ and the negative parity, even spin $(\ensuremath{-},0)$ and odd spin $(\ensuremath{-},1)$ bands are extended from ${30}^{\ensuremath{-}}$ to ${34}^{\ensuremath{-}}$ and from ${31}^{\ensuremath{-}}$ to ${47}^{\ensuremath{-}}$ ${(49}^{\ensuremath{-}}),$ respectively. The high spin experimental spectra are compared with both a simple model involving the occupation of specific single neutron states in the absence of neutron pair correlations and with more detailed cranked Nilsson-Strutinsky calculations in which both proton and neutron pairing correlations are neglected. The very high spin domain is found to comprise a series of unpaired rotational bands. Unpaired band crossings between bands with different neutron and proton configurations are identified in ${}^{161}\mathrm{Er}.$ There is no evidence for aligned oblate or terminating states being close to the yrast line in ${}^{161,162}\mathrm{Er}$ up to spin $\ensuremath{\approx}60\ensuremath{\Elzxh}$ in contrast to the lighter Er isotopes.

Two new rotational bands have been observed in the Dy-152 nucleus following experiments performed using the EUROGAM gamma-ray spectrometer. Several transitions have been observed that link these new bands into the known single-particle states. Using the Doppler shift attenuation method, the quadrupole moment of the previously-known rotational sequence has been measured. The value of Q(band) = 3.85+/-0.06 e b confirms the deformed nature of this cascade. The structures of the three bands are discussed in terms of the occupation of both paired and unpaired orbitals, and are found to be in good agreement with theoretical calculations. The observation of two new bands further extends the concept of shape coexistence in the Dy-152 nucleus.

In a search for exotic structures in odd-odd 164Lu, eight new, presumably triaxial, superdeformed bands were found. Two of the bands are connected to normal-deformed structures and the El strength of the connecting transitions appear to be enhanced over single particle expectations, possibly due to octupole correlations.

Gamma-rays de-exciting a millisecond isomer in the neutron-rich nucleus 74/190W116 have been observed following relativistic projectile fragmentation of a 1 GeV per nucleon 208Pb beam. The isomeric decay populates the ground-state rotational band, with energies that indicate a significant deformation change at Z = 74 for the N = 116 isotones. The successful application of the projectile fragmentation technique in a region of deformed nuclei opens up the prospect of exploiting K-isomer decays to probe the evolution of collective nuclear structure far from the valley of beta stability. (C) 2000 Elsevier Science B.V.

The phenomena of mirror-symmetry and cross-conjugate symmetry have been investigated through a study of nuclei near N = Z at the centre of the \({f_{\frac{7}{2}}}\)shell. Two pairs of mirror-nuclei, 25 49 Mn/ 24 49 Cr and 24 47 Cr/ 23 47 V, have been studied up to their band termination states. Coulomb energies have been deduced and are shown to be an extremely sensitive probe of the spatial correlations of valence particles. A comprehensive new level scheme has been determined for the odd-odd N = Z nucleus 23 46 V, and the results yield new information on the T = 1 (and possibly T = 0) np-pairing modes.

Three new high-$K$ multiquasiparticle intrinsic states, ${K}^{\ensuremath{\pi}}{=(29}^{+}),$ ${K}^{\ensuremath{\pi}}{=30}^{+},$ and ${K}^{\ensuremath{\pi}}{=(34}^{+}),$ have been assigned in ${}^{178}\mathrm{W}.$ The configurations of these states are based on ten, eight, and ten, unpaired nucleons, respectively, and they represent the highest-seniority intrinsic K states observed to date. The $\ensuremath{\gamma}$-ray intensity branching ratios and associated $|{g}_{K}\ensuremath{-}{g}_{R}|$ values have been used to contribute to the specifications of the underlying single-particle configurations of the states. Configuration-constrained potential energy surface calculations indicate that the nucleus retains stably deformed axially symmetric shapes. This evidence, coupled with the experimental $\ensuremath{\gamma}$-ray decay rates, suggests that K remains a good quantum number in these highest-seniority intrinsic state configurations. The aligned angular momenta of the ${K}^{\ensuremath{\pi}}{=(29}^{+}),$ ${K}^{\ensuremath{\pi}}{=30}^{+},$ and ${K}^{\ensuremath{\pi}}{=(34}^{+})$ bands are observed to be lower than those of the other eight quasiparticle, ${K}^{\ensuremath{\pi}}{=25}^{+}$ and ${K}^{\ensuremath{\pi}}{=28}^{\ensuremath{-}}$ bands in ${}^{178}\mathrm{W}.$ These differences are interpreted as the effects of reduced pairing due to blocking by the constituent particles. While the dynamic moments of inertia are similar, they remain substantially less than those of a classical rigid rotor, apparently saturating at a value of about $56{\ensuremath{\Elzxh}}^{2} {\mathrm{MeV}}^{\ensuremath{-}1}.$

A ${K}^{\ensuremath{\pi}}{=8}^{\ensuremath{-}}$ strongly coupled rotational band, which is built upon a 23 ns isomeric state, has been established in ${}^{170}\mathrm{Hf}.$ The single-particle configuration of the band has been determined from the in-band to out-of-band branching ratios and associated $|{(g}_{K}\ensuremath{-}{g}_{R})|{/Q}_{0}$ values. The $\ensuremath{\gamma}$-ray decay of the ${K}^{\ensuremath{\pi}}{=8}^{\ensuremath{-}}$ isomeric state proceeds through a ${K}^{\ensuremath{\pi}}{=6}^{+}$ intrinsic state, in accordance with the K-selection rule. A complex array of delayed $\ensuremath{\gamma}$-ray transitions have been observed to link this ${K}^{\ensuremath{\pi}}{=6}^{+},$ intrinsic bandhead state into the yrast states. In particular, a new $\ensuremath{\Delta}K=8,$ 1141 keV, $E1$ transition links the ${K}^{\ensuremath{\pi}}{=8}^{\ensuremath{-}}$ isomeric state directly to the ground-state band. The $\ensuremath{\gamma}$-ray reduced hindrance factor for this $E1$ decay in ${}^{170}\mathrm{Hf}$ is the smallest $\ensuremath{\Delta}K=8$ transition observed in the Hf nuclei. However, its value is consistent with that expected on the basis of the increased Coriolis mixing which occurs in the lighter Hf isotopes.