[en] Published in summary form only

[en] The Doppler-Shift Attenuation Method has been used to extract transition quadrupole moments of high-spin bands in the N=74 isotones ¹³³Pr, ¹³²Ce and ¹³¹La, produced in the ³⁷Cl + ¹⁰⁰Mo reaction. The results appear to be configuration dependent and, for ¹³³Pr and ¹³²Ce, the involvement of Ω=1/2 νh_9/2 and νf_7/2 intruder orbitals appears to enhance the collectivity at high spin (I>25 ℎ)

[en] The decay out of the πh_11/2νh_11/2 band to the known low-energy levels in ¹³²La was studied using the ¹⁰⁰Mo(³⁶S,p3n) reaction at a bombarding energy of 160 MeV. γ rays were detected by the EUROBALL IV spectrometer. The level scheme of ¹³²La has been deduced using E_γ1 - E_γ2 - E_γ3 triples events which were sorted into RADWARE cubes. The linear polarization of the strongest γ-rays were also measured using the 24 clover detectors as Compton polarimeters. (R.P.)

[en] High-spin states have been studied in ¹²⁸Ce, produced in the ¹⁰⁰Mo(³²S,4n) reaction, using the EUROBALL γ-ray spectrometer. A quadruples analysis (γ⁴) of the data has extended several bands to high spin. Systematics of quasiparticle alignments in cerium isotopes and relevant isotonic chains are discussed and compared to Woods-Saxon cranking calculations

[en] The structure of normally deformed states (β₂∼0.2) in ¹³²Ce has been investigated using EUROGAM2. Eight ΔI=2 bands and three ΔI=1 bands have been identified up to spin 40. The results are interpreted with the aid of Woods-Saxon cranking calculations which suggest a variety of triaxial shapes stabilized by specific active quasiparticle orbitals. (authors)

[en] Compton camera systems can be used to image sources of gamma radiation in a variety of applications such as nuclear medicine, homeland security and nuclear decommissioning. To locate gamma-ray sources, a Compton camera employs electronic collimation, utilising Compton kinematics to reconstruct the paths of gamma rays which interact within the detectors. The main benefit of this technique is the ability to accurately identify and locate sources of gamma radiation within a wide field of view, vastly improving the efficiency and specificity over existing devices. Potential advantages of this imaging technique, along with advances in detector technology, have brought about a rapidly expanding area of research into the optimisation of Compton camera systems, which relies on significant input from Monte-Carlo simulations. In this paper, the functionality of a Compton camera application that has been integrated into GAMOS, the GEANT4-based Architecture for Medicine-Oriented Simulations, is described. The application simplifies the use of GEANT4 for Monte-Carlo investigations by employing a script based language and plug-in technology. To demonstrate the use of the Compton camera application, simulated data have been generated using the GAMOS application and acquired through experiment for a preliminary validation, using a Compton camera configured with double sided high purity germanium strip detectors. Energy spectra and reconstructed images for the data sets are presented.

[en] The three superdeformed (SD) bands in ¹³²Ce and the two SD bands in ¹³¹Ce have been extended to higher spin, following experiments with the Euroball IV spectrometer. The two SD bands in ¹³¹Ce have been linked together. However, despite the relatively high population intensity of the bands (up to 5% of the respective channel), it has not been possible to unambiguously link any of the five SD bands into the low-spin, normally deformed structures of ^131,132Ce. At the highest spins (>60(ℎ/2π)), some of the bands exhibit the characteristic behavior of smooth band termination, i.e., energetically costly angular-momentum generation near the finite mesoscopic limit. Configuration-dependent cranked Nilsson-Strutinsky calculations have been performed to suggest single-particle configurations for the SD bands and to investigate the possibility of termination in these bands

[en] Nuclear medical imaging modalities such as positron emission tomography and single photon emission computed tomography are used to probe physiological functions of the body by detecting gamma rays emitted from biologically targeted radiopharmaceuticals. A system which is capable of simultaneous data acquisition for nuclear medical imaging and magnetic resonance imaging is highly sought after by the medical imaging community. Such a device could provide a more complete medical insight into the functions of the body within a well-defined structural context. However, acquiring simultaneous nuclear/MRI sequences are technically challenging due to the conventional photomultiplier tube readout employed by most existing scintillator detector systems. A promising solution is a nuclear imaging device composed of semiconductor detectors that can be operated with a standard MRI scanner. However, the influence of placing a semiconductor detector such as high purity germanium (HPGe) within or close to the bore of an MRI scanner, where high magnetic fields are present, is not well understood. In this paper, the performance of a HPGe detector operating in a high strength static (B_S) MRI field along with fast switching gradient fields and radiofrequency from the MRI system has been assessed. The influence of the B_S field on the energy resolution of the detector has been investigated for various positions and orientations of the detector within the magnetic field. The results have then been interpreted in terms of the influence of the B_S field on the charge collection properties. MRI images have been acquired with the detector situated at the entrance of the MRI bore to investigate the effects of simultaneous data acquisition on detector performance and MRI imaging.

[en] The decay out of the πh_11/2νh_11/2 band to the known low-energy levels in ¹³²La was studied using the reaction ¹⁰⁰Mo+³⁶S at 160 MeV beam energy. The low-energy level scheme has been further developed and unambiguous spin and parity values have been assigned to the levels connecting the band to the 6^- isomeric state. According to the new level scheme the spins in the πh_11/2νh_11/2 band are shifted up by one unit compared to the earlier tentative experimental values. The obtained new spins prove the existence of signature inversion in ¹³²La and give further support to the spin assignments made for the πh_11/2νh_11/2 bands in the neighbouring odd-odd La isotopes from level energy systematics. (orig.)

[en] The Doppler-Shift Attenuation Method has been used to extract transition quadrupole moments of high-spin bands in the $\text{N=74}$ isotones ¹³³Pr, ¹³²Ce and ¹³¹La, produced in the ³⁷Cl$\text{+}$¹⁰⁰Mo reaction. The results appear to be configuration dependent and, for ¹³³Pr and ¹³²Ce, the involvement of $\text{Ω=1/2}$ $\text{νh}{}_{\mathrm{9/2}}$ and $\text{νf}{}_{\mathrm{7/2}}$ intruder orbitals appears to enhance the collectivity at high spin ($\text{I>25}\text{ℏ}$).