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Abstract: New level schemes of 112,114,115,116,117,118Pd are established by means of , and measurements of prompt fission γ rays from 252Cf using the Gammasphere multi-detector array. Spins/parities were assigned to levels based on angular correlation measurements, level systematics and decay patterns. In the even-N isotopes 112,114,116Pd, two sets of odd-parity bands were identified and extended with spins measured in each band. The odd-parity bands with large level staggerings were interpreted as disturbed chirality with less pronounced triaxial deformations in the Pd isotopes than observed in the chiral symmetry breaking 110,112Ru with maximum triaxiality. Onset of wobbling motion was identified from the sign of the signature splitting in the γ band of even–even 114Pd, and probably also in 116Pd, as first seen in the isotone 112Ru. Maximal triaxiality in Ru and Pd isotopes is found to be reached for , 112Ru and 114Pd, 4 neutrons more than predicted in the theoretical calculations. The new data and TRS calculations allowed a systematic study of the band crossings in the even-N 112,114,116Pd and odd-N 115,117Pd isotopes. Now we find a new overall, more complex shape evolution than previously proposed from triaxial prolate in 110Pd via triaxial oblate in 112Pd to nearly oblate in 114,116Pd with a large change of the triaxial deformation parameter γ toward nearly oblate in the alignment in 114,115,116,117,118Pd, and triaxial-prolate–triaxial-oblate shape coexisting bands in 115Pd. [Copyright &y& Elsevier]

High-spin states in 122Te were populated in the reaction 82Se(48Ca, α4n)122Te at a beam energy of 200 MeV and γ-ray coincidences were measured with the Gammasphere spectrometer. The previously known level scheme was extended to considerably higher spin. Maximally aligned states and several high-energy transitions feeding into some of these levels were observed. In addition, seven collective high-spin bands were discovered for the first time in this nucleus. The experimental results are compared with cranked Nilsson-Strutinsky model calculations and possible configuration assignments to the new high-spin structures are discussed. [ABSTRACT FROM AUTHOR]

The 88Kr nucleus has been reinvestigated with prompt-y-ray-spectroscopy methods using the Gammasphere Ge array to measure y rays following spontaneous fission of 252 Cf. The order of some of the transitions, reported previously, has been changed and new levels were introduced. Angular correlation analysis allowed the assignment of spins to several levels in 88Kr. These data, together with the shell-model calculations, explained the near-yrast structure of 88Kr, which is similar to the structure of the N = 52, 90Sr, and 92Zr isotones. The regular systematics obtained for the three isotones suggests that the spin of the 2073.4-keV level in the 86Se isotone is different from the l = 6 value reported previously. Using data from prompt y-ray measurement of spontaneous fission of 248Cm, we reinvestigated the 86Se nucleus. A new candidate for the level in 86Se has been proposed, which is supported by shell-model calculations. Energies of the 21+ and 41+ levels in the 82Zn nucleus have been predicted using a novel systematics. [ABSTRACT FROM AUTHOR]

Abstract: The transition quadrupole moments, , of rotational bands in the neutron-rich, even-mass 102–108Mo and 108–112Ru nuclei were measured in the 8–16 ℏ spin range with the Doppler-shift attenuation method. The nuclei were populated as fission fragments from 252Cf fission. The detector setup consisted of the Gammasphere spectrometer and the HERCULES fast-plastic array. At moderate spin, the moments are found to be reduced with respect to the values near the ground states. Attempts to describe the observations in mean-field-based models, specifically cranked relativistic Hartree–Bogoliubov theory, illustrate the challenge theory faces and the difficulty to infer information on γ softness and triaxiality from the data. [Copyright &y& Elsevier]

The neutron-rich nucleus n2Rh has been reinvestigated by examining the prompt γ rays emitted in the spontaneous fission of 252Cf with the Gammasphere detector array. A new side band was built in 112Rh. Total Routhian surface calculations have been performed and confirm the role of triaxiality in the negative-parity structure of 112Rh. [ABSTRACT FROM AUTHOR]

Two distinct sets of chiral-partner bands have been identified in the nucleus 133Ce. They constitute a multiple chiral doublet, a phenomenon predicted by relativistic mean field (RMF) calculations and observed experimentally here for the first time. The properties of these chiral bands are in good agreement with results of calculations based on a combination of the constrained triaxial RMF theory and the particle-rotor model. [ABSTRACT FROM AUTHOR]

Excited states of 76Ge have been populated in above-barrier Coulomb excitation and inelastic scattering of a 530-MeV 76Ge beam on a 238U target and studied using in-beam γ-ray spectroscopy with the Gammasphere array. The γ band was extended considerably and one new band was identified. Comparisons of the γ band with collective- and shell-model calculations suggest that 76Ge may be a rare example of a nucleus exhibiting rigid triaxial deformation in the low-lying states. [ABSTRACT FROM AUTHOR]

Although the observation of wobbling was once thought to be possibly confined to lutetium isotopes in N≈94 nuclei, the identification of this exotic collective mode in 167Ta has raised the question of the role of the proton Fermi surface with regard to this phenomenon. To investigate this issue, an experiment was performed to populate high-spin states in the N = 94 nucleus 169Re. The heavy-ion reaction 55Mn + 118Sn was used in conjunction with Gammasphere to detect the emitted γ rays. More than 130 new transitions were added to the 169Re level scheme, including the first identification of the πi13/2 rotational sequence in this nucleus. This configuration is the structure on which all known wobbling sequences are based, but no wobbling band was observed, likely owing to the fact that the πi13/2 sequence is located at a relatively high energy in comparison with the other structures found in 169Re. Nine decay sequences are now established in this nucleus and are described within the context of the cranked shell model. In addition, significant extension of the level scheme of the odd-odd 170Re nucleus was possible and a discussion of the residual interactions for the πh9/2vi13/2 and πi13/2vi13/2 configurations in this region is given as well. [ABSTRACT FROM AUTHOR]

High-spin states in 123I were populated in the reaction 80Se(48Ca,p4n)123I at a beam energy of 207 MeV and y-ray coincidence events were measured using the Gammasphere spectrometer. Three weakly populated, high-spin rotational bands have been discovered with characteristics similar to those of the long collective bands recently observed in other nuclei of this mass region. Configuration assignments are proposed based on calculations within the framework of the cranked Nilsson-Strutinsky approach. [ABSTRACT FROM AUTHOR]

Recent antisymmetrized molecular dynamics (AMD) calculations for 28Si suggest the presence of a superdeformed (SD) band with a dominant 24Mg + α clustering for its configuration, with firm predictions for its location and associated moment of inertia. This motivates a review of the experimental results reported in the literature with a particular focus on 24Mg(α,γ) studies, as well as on a-like heavy-ion transfer reactions such as 12C(20Ne,α)28Si. Combining this information for the first time leads to a set of candidate SD states whose properties point to their α-cluster structure and strong associated deformation. Analysis of data from Gammasphere allows the electromagnetic decay of these candidate states to be probed and reveals further supporting evidence for such a structure. This paper appraises this body of information and finds the evidence for an SD band is strong. [ABSTRACT FROM AUTHOR]

The low-spin level scheme of 68Ni was investigated with the Gammasphere array following reactions between a 70Zn beam and 238U, 208Pb, and 197Au targets. Spin assignments for some states have been verified through y-ray angular correlations, including the 0+ assignment for the 2511-keV level. Two previously unknown states at 3302 and 3405 keV have been identified. No evidence was found for a recently reported 216-ns, 0+ isomer at 2202 keV that was attributed to a proton two-particle, two-hole intruder configuration, despite experimental conditions similar to those used in the measurement reporting its discovery. [ABSTRACT FROM AUTHOR]

An experimental study of the 62Zn nucleus has been performed by combining the data sets from four fusion-evaporation reaction experiments. Apart from the previously published data, the present results include ten new rotational band structures and two more superdeformed bands. The Gammasphere Ge-detector array in conjunction with the 4? charged-particle detector array Microball allowed for the detection of γ rays in coincidence with evaporated light particles. The deduced level scheme includes some 260 excited states, which are connected with more than 450 λ-ray transitions. Spins and parities of the excited states have been determined via directional correlations of λ rays emitted from oriented states. The experimental characteristics of the rotational bands are analyzed and compared with results from cranked Nilsson-Strutinsky calculations. The present analysis, combined with available experimental results in the A ~ 60 mass region, can be used to improve the current set of Nilsson parameters in the N = 3 and N = 4 oscillator shells. [ABSTRACT FROM AUTHOR]

Abstract: A particle- coincidence technique has been used to measure the fusion cross-section in the system 12C+12C at low beam energies. Based on these results, it should be possible to measure this important fusion cross-section down to the 10pb level within a week-long run. [Copyright &y& Elsevier]

Decay of the long-lived (T1/2 = 160.44 d) Kπ = 23/2- isomer in l77Lu was investigated using a chemically purified source and the Gammasphere array. New, high-multipolarity M3 and E4 deexcitation branches to the known Iπ = 17/2- and 15/2- members of the π9/2- [514] band were discovered. The reduced hindrance factors per degree of K forbiddenness deduced for these two transitions are found to be relatively large when compared to similar decays from the Kπ = 37/2- (T1/2 = 51.4 min) and Kπ = 16+ (T1/2 = 31 yr) isomers in l77Hf and l78Hf, respectively. This is attributed to significant configuration changes that occur in the decay of this l77Lu isomer. [ABSTRACT FROM AUTHOR]

The nuclei 65-67Cu were studied in reactions between a 430-MeV 64Ni beam and a thick 238U target with the Gammasphere array. Decay schemes for both nuclei have been extended, with spin and parity assignments of observed states constrained by measured &ggr;-ray angular distributions and correlations. Positive-parity level structures, based on p3/2 protons coupled to negative-parity states in the Ni cores, have been identified above the known 9/2+ states. In 67Cu, a negative-parity dipole band built upon a πf-17/2 state has been observed, as were two shorter negative-parity sequences. A qualitative description of the level structures has been obtained through comparison with systematics of the odd-A57-51Cu isotopes and with states in the neighboring even-even Ni and Zn cores. Shell-model calculations using JUN45 and jj44b effective interactions were performed for 65,67Cu, with jj44b providing overall better agreement with the data. Both are limited, however, by the restriction that the f7/2 and g9/2 orbitals are not available simultaneously in the basis. Proton f7/2 and neutron g9/2 orbitals are required for the full negative-parity spectrum of states, while g9/2 protons and neutrons are both important for positive-parity levels. The latter states are found to be better described in terms of weak coupling of a proton to the Ni core. [ABSTRACT FROM AUTHOR]

The medium-spin structure of the 92Rb nucleus, populated in spontaneous fission of 248Cm and 252Cf, has been studied using the EUROGAM2 and the GAMMASPHERE Ge arrays, respectively. Two isomers have been found in 92Rb at 284.2 and 1958.2 keV with half-lives of T1/2 = 54(3) ns and T1/2 = 7(2) ns, respectively. A measurement of neutron-induced fission of 235U, at the PF1B cold-neutron beam facility of the Institut Laue Langevin, Grenoble, has been performed to confirm the assignment of the T1/2 = 54(3) ns, 284.2-keV isomeric level to the 92Rb nucleus. Excited levels in 92Rb and 94Rb nuclei have been calculated in a large-scale shell-model framework. Isomers observed in these two nuclei have been interpreted as proton-neutron configurations involving the high-,j ν1h11/2 and &pgr;\g9/2 orbitals. [ABSTRACT FROM AUTHOR]

High-spin states in 120Te were populated in the reaction 80Se(>48Ca,&agr;4n))120Te at a beam energy of 207 MeV and &ggr;-ray coincidences were measured using the Gammasphere spectrometer. The previously known level scheme is extended to higher spin and new interband transitions and side-feeding branches are established. Five highly deformed rotational bands, extending up to almost l = 50, are observed for the first time. The bands are compared with similar structures found recently in neighboring nuclei. The experimental results are interpreted within the framework of the cranked Nilsson-Strutinsky model. Configuration assignments to several terminating states and to the high-spin bands are discussed. [ABSTRACT FROM AUTHOR]

Excited states in the Z = 19, N = 29 neutron-rich 48K isotope have been studied using deep-inelastic transfer reactions with a thick target at Gammasphere and with a thin target at the PRISMA-CLARA spectrometer. The lowest excited states were located; they involve a proton hole in the s1/2 or d3/2 orbital coupled to a p3/2 neutron. A new 7.1(5)-ns, 5+ isomer, the analog of the 7/2- isomer in 47K. was identified. Based on the observed y-decay pattern of the isomer a revised spin-parity assignment of 1- is proposed for the ground state of 48 K. [ABSTRACT FROM AUTHOR]

High-spin states have been studied in Due to image rights restrictions, multiple line equation(s) cannot be graphically displayed. populated through the 116Cd(23Na,4n) reaction at 115 MeV, using the Gammasphere γ-ray spectrometer. The negative-parity yrast band has been significantly extended to spin ~45ħ and excitation energy 21.5 MeV, showing evidence for several rotational alignments. The positive-parity yrast band of Due to image rights restrictions, multiple line equation(s) cannot be graphically displayed., populated through the p4n channel of this reaction, was also populated to spin ~38ħ and excitation energy 18 MeV. Cranking calculations indicate that these nuclei are soft with respect to the triaxiality parameter γ and that several competing nuclear shapes occur at high spin. [ABSTRACT FROM AUTHOR]

Medium- and high-spin states of 134Pr were populated using the 116Cd(23Na, 5n) reaction and studied with the GAMMASPHERE spectrometer. Several new bands have been found in this nucleus, one of them being linked to the previously observed chiral-candidate twin-band structure. The ground state of 134Pr could be determined through establishing a level structure that connects the two previously known long-lived isomeric states. Unambiguous spin-parity assignments for the excited states could be performed based on the known 2- spin-parity of the ground state combined with the present experimental data. Intrinsic single-particle configurations have been assigned to the newly observed bands on the basis of the measured B(M1)/B(E2) ratios, alignments, band-crossing frequencies, bandhead spins, the observed single-particle configurations in the neighboring nuclei, and taking into account the predictions of total Routhian surface and tilted-axis cranking calculations. [ABSTRACT FROM AUTHOR]

The odd-odd neutron-rich nucleus 152Pr has been studied from the spontaneous fission of 252Cf with Gammasphere. A high-spin level scheme of 152Pr has been established for the first time. Angular correlation and internal conversion coefficient measurements are used to determine the transition multipolarities. The possible configurations of the bandhead have been discussed based on systematics and total Routhian surface calculations. [ABSTRACT FROM AUTHOR]

Gamma rays assigned to Due to image rights restrictions, multiple line equation(s) cannot be graphically displayed. have been identified with Gammasphere in deep-inelastic reactions involving a 450-MeV 76Ge beam and a 198Pt target. Using a combination of spectra produced by double gates on the known 454-, 843-, and 1095-keV members of the ground-state cascade, a coincident line at 199 keV has been identified and is tentatively assigned as the 8+ → 6+ transition. These γ-ray coincidences have been observed only in prompt events, indicating an 8+ half-life below 20 ns and requiring a large B(E2) enhancement compared to that expected from a seniority scheme. This value is consistent with models showing decay to a seniority v = 4, 6+ level that is depressed by the same two-body interaction responsible for the rather low 1095-keV Due to image rights restrictions, multiple line equation(s) cannot be graphically displayed. energy, as compared to the valence-symmetry counterpart Due to image rights restrictions, multiple line equation(s) cannot be graphically displayed. [ABSTRACT FROM AUTHOR]

An investigation of the yrast structure of the odd-Z 159Ho nucleus to high spin has been performed. The 159Ho nucleus was populated by the reaction 116Cd(48Ca,p4nγ) at a beam energy of 215 MeV, and resulting γ decays were detected by the Gammasphere spectrometer. The h11/2 yrast band has been significantly extended up to IΠ=75/2- (tentatively 79/2-). A lower frequency limit for the second (h11/2)2 proton alignment was extracted consistent with the systematics of this alignment frequency, indicating an increased deformation with neutron number in the Ho isotopes. The energy-level splitting between the signature partners in the h11/2 structures of the Ho isotopes and the neighboring N=92 isotones is discussed. [ABSTRACT FROM AUTHOR]

High-spin states in 125I have been investigated using the reaction 82Se(48Ca, p4n) at a beam energy of 200 MeV and γ-ray coincidence events were detected using the Gammasphere spectrometer. A deformed rotational band, extending up to IΠ=95/2-, was observed for the first time in a heavier odd-A iodine nucleus. The characteristics of the band are very similar to those of the highly deformed bands observed recently in neighboring nuclei and it is essentially identical to one of the previously known bands in 126Xe. The experimental results are compared to cranked Nilsson-Strutinsky calculations and possible configurations for the band are discussed. [ABSTRACT FROM AUTHOR]

Abstract: Four previously known rotational bands in 76Rb have been extended to moderate spins using the Gammasphere and Microball γ ray and charged particle detector arrays and the 40Ca(40Ca, 3pn) reaction at a beam energy of 165 MeV. The properties of two of the negative-parity bands can only readily be interpreted in terms of the highly successful Cranked Nilsson–Strutinsky model calculations if they have the same configuration in terms of the number of particles, but they result from different nuclear shapes (one near-oblate and the other near-prolate). These data appear to constitute a unique example of shape coexisting structures at medium spins. [Copyright &y& Elsevier]

Low-lying collective states in 126Xe have been investigated via the 12C(l26Xe,126Xe*) projectile Coulomb excitation reaction at 399 MeV. The y decays were detected with the Gammasphere array. Coulomb excitation cross sections relative to the 21+ state were obtained. Twenty-two absolute E2 transition strengths have been deduced. An sd-interacting boson model (IBM-1) fit agrees well with the new experimental data. This makes a quantitative test of O(6)-symmetry breaking in 126Xe possible. The measured absolute B(E2) values indicate a preservation of O(5) symmetry, while the O(6) symmetry is broken. The evolution of O(6)-symmetry breaking and of O(5)-symmetry conservation in the 124,126,128Xe isotopic chain is discussed. [ABSTRACT FROM AUTHOR]

Weakly populated band structures have been established in 156Er at low to medium spins, following the 114Cd(48Ca,6nγ) reaction at 215 MeV. High-fold γ-ray coincidence data were recorded in a high-statistics experiment with the Gammasphere spectrometer. Bands built on the second 0+ and 2+ (γ-vibrational) states have been established. A large energy staggering between the even- and odd-spin members of the γ-vibrational band suggests a γ-soft nature of this nucleus. An additional band is discussed as being based on a rotationally aligned (πh9/2, f7/2)² structure, coexisting with the systematically observed, more favorable (υi3/2)² aligned structure seen in this mass region. [ABSTRACT FROM AUTHOR]

A spectroscopic investigation of the γ decays from excited states in 160Er has been performed in order to study the changing structural properties exhibited from low spin up toward ultrahigh spin (I ∼ 160ℏh). The nucleus 160Er was populated by the reaction 116Cd(48Ca,4nγ) at a beam energy of 215 MeV, and resulting γ decays were studied using the Gammasphere spectrometer. New rotational structures and extensions to existing bands were observed, revealing a diverse range of quasiparticle configurations, which are discussed in terms of the cranked shell model. At spins around 50ℏ there is evidence for oblate states close to the yrast line. Three rotational bands that have the characteristics of strongly deformed triaxial structures are observed, marking a return to collectivity at even higher spin. The high-spin data are interpreted within the framework of cranked Nilsson-Strutinsky calculations. [ABSTRACT FROM AUTHOR]

Abstract: The level scheme of odd-Z neutron-rich 141Cs (, ) was extended and expanded and that of 144Cs () was identified for the first time by means of coincidence measurements of prompt γ rays in the spontaneous fission of 252Cf with Gammasphere. Spin/parity was assigned to the levels based on angular correlations and level systematics in 141,143Cs. Parity doublets characteristic of both simplex quantum number and were proposed in 141Cs. The tests by using rotational frequency ratio imply octupole vibrations in 141Cs and 143Cs. values and electric dipole moments were calculated for 141Cs, and re-determined for 143Cs. It was found that values of 141Cs are simplex-dependent and the average value is one order of magnitude larger than that of 143Cs, and the deduced dipole moment of 141Cs is considerably larger than that of 143Cs, and comparable to the isotone 142Ba. For 144Cs the yrast sequence looks like a well-deformed rotational band, but no octupole band structure was identified in this nucleus. The overall variations of in 141,143,144Cs exhibit a pronounced drop of dipole moment with increasing neutron number in this odd-Z isotopic chain, which may be analogous in nature to the quenching of observed in even–even 146Ba (, ) and 224Ra (, ), and to the drop of in the odd-Z neutron-rich 147La (, ) reported by our collaboration. [Copyright &y& Elsevier]

Abstract: Excited states in 124Xe have been studied via the 12C(124Xe, 124Xe∗) Coulomb excitation reaction. Their population cross-sections relative to the state have been determined from the γ-ray yields observed with Gammasphere. More than twenty absolute E2 strengths for seven off-yrast, low-spin states of 124Xe have been deduced for the first time. The absolute values indicate pronounced symmetry, even for the off-yrast states with high quantum number τ, while the symmetry is substantially broken. [Copyright &y& Elsevier]

Two similar sets of odd-parity bands are observed in each of three even–even neighbors, 108,110,112Ru, from a study of prompt spontaneous-fission gamma rays at Gammasphere. A careful study of the odd-parity levels of these nuclei shows evidence for the features of chiral doubling. Comparisons are made with reported other candidates for chiral doubling. [ABSTRACT FROM AUTHOR]

High-spin, even-parity bands in neutron-rich 108, 110, 112Ru nuclei were reinvestigated and considerably expanded by measuring many-fold prompt γ-ray coincidence events following the spontaneous fission of 252Cf with Gammasphere. Our high statistics data allow us to detect weaker transitions and bands not previously published. Also, gamma branching ratios, which are important for theory, are carefully measured from all levels. In 110Ru, we find a doubling of levels for both ground and quasi-gamma bands above the 8+ levels. There are likely two-phonon quasi-gamma bands in 110, 112Ru, as well as a bandhead level in 108Ru. The odd–even spin energy band staggering observed in the quasi-gamma bands in 108, 110, 112Ru and the doubling of levels in 110Ru present a challenge to theory. [ABSTRACT FROM AUTHOR]

Abstract: An interlock system is described that allows volatile targets to be prepared in an evaporator, sealed under vacuum, transported to the -array Gammasphere, and inserted into the reaction chamber for experiments, while maintaining a vacuum better than . The performance of the system is demonstrated for lithium metal targets. A comparison is made between lithium targets covered by a gold evaporation to reduce oxidation and open metal targets transferred in the interlock. [Copyright &y& Elsevier]

The Improved Landmine Detector System, a militarily fielded, teleoperated vehicle-mounted multi-sensor landmine detector, uses a thermal neutron analysis (TNA) detector to con- firm the presence of a mine by detecting the bulk nitrogen in its explosives. To improve the nitrogen sensitivity or measurement times of the TNA detector, higher gamma ray rates will be required. The chief bottleneck to achieving the maximum possible performance from the present TNA or future versions is the relatively slow fluorescent decay time of the NaI(Tl) scintillators which are currently used. An experimental investigation was undertaken to compare a number of modern, fast inorganic scintillators to NaI(Tl) with respect to parameters relevant to TNA landmine detection, including efficiency, energy resolution, linearity, avail- able size and cost. This paper presents results in the context of the high-rate, high-gamma-energy environments expected in such a TNA application. Large (7.62 cm x 7.62 cm) LaBr3 :Ce scintillators, and to a lesser degree LaCl3 :Ce, were found to stand-out as as the principal candidates for the detector upgrade to the TNA confirmation system. Their properties also make them ideal candidates for fast neutron analysis and associated particle imaging bulk explosives detectors. [ABSTRACT FROM AUTHOR]

It has been shown that I-124 PET imaging can be used for accurate dose estimation in radio-immunotherapy techniques. However, I-124 is not a pure positron emitter, leading to two types of coincidence events not typically encountered: increased random coincidences due to non-annihilation cascade photons, and true coincidences between an annihilation photon and primarily a coincident 602 keV cascade gamma (true coincidence γ-ray background). The increased random coincidences are accurately estimated by the delayed window technique. Here we evaluate the radial and time distributions of the true coincidence γ-ray background in order to correct and accurately estimate lesion uptake for I-124 imaging in a time-of-flight (TOF) PET scanner. We performed measurements using a line source of activity placed in air and a water-filled cylinder, using F-18 and I-124 radio-isotopes. Our results show that the true coincidence γ-ray backgrounds in I-124 have a uniform radial distribution, while the time distribution is similar to the scattered annihilation coincidences. As a result, we implemented a TOF-extended single scatter simulation algorithm with a uniform radial offset in the tail-fitting procedure for accurate correction of TOF data in I-124 imaging. Imaging results show that the contrast recovery for large spheres in a uniform activity background is similar in F-18 and I-124 imaging. There is some degradation in contrast recovery for small spheres in I-124, which is explained by the increased positron range, and reduced spatial resolution, of I-124 compared to F-18. Our results show that it is possible to perform accurate TOF based corrections for I-124 imaging. [ABSTRACT FROM AUTHOR]

Abstract: The potential of incorporating three-quanta annihilation into positron emission tomography (PET) to detect local tissue chemistry was investigated using the GAMMASPHERE facility, which features a spherical array of 110 Compton-suppressed high-purity germanium (HPGe) detectors. Fluoro-2-deoxyglucose (FDG) containing was introduced into 11 samples of haemolysed blood, serum, cell concentrate and whole blood, some of which had been either oxygenated or deoxygenated. The relative three-quanta yield was estimated from the reduced counts in the full-energy photopeak at 511keV. Compton-suppression produced larger effects in the calculations than time-gating, suggesting its importance for this method of estimation. The relative three-quanta yields were found to vary as much as 11% between the samples. This level of sensitivity to different biological samples commends three-quanta annihilation for molecular imaging. [Copyright &y& Elsevier]

The 110-Ge and 770-BGO detectors array GAMMASPHERE is simulated. A schematic geometry and the physical processes related to nuclear spectroscopy are included in order to analyze procedures especially designed to investigate the nuclear conctinuum. [ABSTRACT FROM AUTHOR]

Abstract: The yrast and near-yrast level scheme of light neutron-rich 143La (, ) is reinvestigated and expanded and that of 144La () is proposed for the first time by measuring prompt γ rays from the spontaneous fission of 252Cf at Gammasphere. Spins/parities are assigned to the lowest-lying levels of 143,144La based on the early studies of decay, and the assignments for high-spin levels of 143,144La are made by measuring internal conversion coefficients and following the level systematics of the neighboring heavier La isotopes and even–even Ba and Ce nuclei. The ratios, energy displacements and rotational frequency ratios of the new parity-doublets of 143,144La indicate that octupole deformations/correlations also develop in these nuclei. The band-crossings observed in a rotational frequency range of 0.31 to 0.34 MeV for the two even-parity bands in 143La but being absent in 144La are interpreted as due to alignment of a pair of neutrons in 143La. [Copyright &y& Elsevier]

A largely extended experimental knowledge of the 61 29Cu32 nucleus has been obtained from three experiments. Excited states in 61Cu were produced via the fusion-evaporation reaction 28Si(36Ar, 3p)61Cu . In addition to the Ge array GAMMASPHERE, neutron and charged-particle detectors placed around the target position were used for high-performance particle spectroscopy. The constructed level scheme includes more than 160 energy levels and 320 γ -ray transitions belonging to both normally deformed as well as superdeformed rotational structures. The multipolarities have been determined for the γ -ray transitions and as a result spin-parity assignments are given for nearly all energy levels. Experimental results in the normally deformed region are compared with predictions from large-scale shell model calculations. The collective structures are compared with results from cranked Nilsson-Strutinsky calculations. The results reveal the need to modify the standard Nilsson parameters in the mass A ∼ 60 region. [ABSTRACT FROM AUTHOR]

A largely extended experimental knowledge of the 61 29Cu32 nucleus has been obtained from three experiments. Excited states in 61Cu were produced via the fusion-evaporation reaction 28Si(36Cu . In addition to the Ge array GAMMASPHERE, neutron and charged-particle detectors placed around the target position were used for high-performance particle spectroscopy. The constructed level scheme includes more than 160 energy levels and 320 γ -ray transitions belonging to both normally deformed as well as superdeformed rotational structures. The multipolarities have been determined for the γ -ray transitions and as a result spin-parity assignments are given for nearly all energy levels. Experimental results in the normally deformed region are compared with predictions from large-scale shell model calculations. The collective structures are compared with results from cranked Nilsson-Strutinsky calculations. The results reveal the need to modify the standard Nilsson parameters in the mass A ∼ 60 region. [ABSTRACT FROM AUTHOR]61Cu . In addition to the Ge array GAMMASPHERE, neutron and charged-particle detectors placed around the target position were used for high-performance particle spectroscopy. The constructed level scheme includes more than 160 energy levels and 320 γ -ray transitions belonging to both normally deformed as well as superdeformed rotational structures. The multipolarities have been determined for the γ -ray transitions and as a result spin-parity assignments are given for nearly all energy levels. Experimental results in the normally deformed region are compared with predictions from large-scale shell model calculations. The collective structures are compared with results from cranked Nilsson-Strutinsky calculations. The results reveal the need to modify the standard Nilsson parameters in the mass A ∼ 60 region. [ABSTRACT FROM AUTHOR]

Excited states in 124Xe were populated in the reaction 82Se(48Ca, 6 n)124Xe and γ -ray coincidence relationships were measured with the Gammasphere spectrometer. Two new bands are observed and several of the previously known bands are extended in the high- as well as in the low-spin region. Two irregular high-spin structures are also added. The irregularities are a fingerprint of a transition from collective to non-collective behaviour. Configuration assignments to the new structures are proposed on the basis of systematics and by comparing experimental properties with calculations within the framework of the cranking model. [ABSTRACT FROM AUTHOR]

Abstract: Prompt –– coincidence measurements of –114 neutron-rich nuclei populated in the spontaneous fission of 252Cf were made with Gammasphere. The high statistics data, 5.7×10 11 triples and higher folds, opened up discoveries of new band structures and significant extensions of previously known bands. The new data for ground bands in 99,101Y, 101,105Nb, 105,107,109,111Tc and 111,113Rh when compared with one quasi-particle plus triaxial rotor calculation, revealed a smooth transition from axial symmetry in 99,101Y to maximize triaxiality in 111,113Rh. In 106Mo, 110,112Ru, pairs of doublet bands are established to high spins. Their constant and equal kinetic moments of inertia, small energy differences between states of the same spin and very similar B(E2)/B(M1) ratios for each band in these nuclei suggest that these are chiral doublet bands. If they are not chiral, then a new symmetry is indicted. Extended one- and new two-phonon -vibrational bands are observed in 110,112Ru. The extended one-phonon bands in 104-108Mo, and 108-112Ru exhibit an unexpected reversal in the energy level staggering pattern with spin. The first one- and two-phonon -bands in an odd- nucleus are seen in 105Mo with level energies almost identical to these same bands known in 104Mo. [Copyright &y& Elsevier]