No abstract available

[en] A γ-ray imaging method is described which is suitable for non-destructive and non-invasive determination of amount and distribution of matter in objects. A point-like positron source is placed in front of the object to be examined. A position detector behind the source measuring 511 keV γ-rays from positron annihilation determines the direction of the correlated 511 keV γ-rays used to probe the object. Detecting the probing γ-ray after transmission through or scattering off the object in time coincidence to the position determining γ-ray enables to map the thickness and density distribution of the object. The method and system can be employed for security inspection of concealed items, control of erosion, deposition and structural defects, and the detection of land mines

[en] The new ΔE/E detection system, calorimeter telescope (CATE), for charge and mass determination of heavy ions at high energies (≥100 MeV/n) has been designed. CATE, a calorimeter telescope will consist of position sensitive Si detectors for ΔE determination and scintillators, readout by either PIN diode or PMT, for total-E determination. Different scintillation detectors were tested with ¹³⁰Sn, ¹⁸⁶Pb, ¹⁹⁷Au and ²³⁸U beams of (100-300) MeV/n ion energy. By properly selecting the beam species from the FRS and applying position corrections, an energy resolution of ≅0.5% FWHM was observed. The corresponding mass resolution of 1/200 is adequate for employment of CATE in the Fast Beam RISING campaign at GSI

No abstract available

[en] Isomeric states in ^210-215Ra have been populated by the decay of the compound nuclei ^216,220Ra produced in irradiations of ^204,208Pb with ¹²C at E_lab=(68-136) MeV. Published values for γ-ray energies and half-lives were confirmed for ^212m-215mRa. Our data for ^210mRa agree with the γ-energies and the half-life measured at the RITU separator, University of Jyvaeskylae (Finland). Its decay pattern is complex. Two series of γ-rays of E_γ=96.7,774.6, 578.0,604.5 keV and E_γ=96.7,602.1,750.5,604.5 keV were observed. A half-life of (2.36±0.04) μs was measured. The isomeric state is attributed to an 8⁺ state at E^*=2053.8keV. A previously unknown isomeric state was assigned to ^211mRa. It has a half-life of (4.0±0.5) μs and it decays by emission of γ-rays with energies of 396.1 keV and 802.0 keV. It is attributed to a 13/2⁺ state at E^*=1198.1 keV. (orig.)

[en] Temperature distributions of cooled Germanium (Ge) detectors are calculated by the COMSOL MULTIPHYSICS software in order to determine the necessary cooling power of an electromechanical cooling engine. For a single Ge-crystal heat losses of 2.5 W are determined which increase to 5.7 W for a composite detector with three Ge-crystals. The energy transfer may be reduced substantially by a heat reflector which will allow the electromechanical cooling engine to keep also the composite Ge-detector under desirable temperature. (authors)

[en] The electric field distribution in a planar HPGe pixel detector is investigated and the attention is drawn on the effects in the peripheral region. The detector is considered with its enclosure (encapsulation) and the leakage current and the surface charge distribution of tile detector channel is also taken into account. It is shown that electric potential distortions appear near the crystal periphery. For standard detector geometry a layer of few millimetres (up to 10) is found where the distortion is still significant. The effect depends strongly on the surface state and is less influenced by the capsule geometry (the distance from the capsule wall and the germanium crystal) and the bias voltage. The pixel size and the distance between the pixels are varied in order also to test the extent of the enclosure effects. (orig.)

[en] A new high-spin isomer in the neutron-rich nucleus ¹²⁸Cd was populated in the projectile fission of a ²³⁸U beam at the Radioactive Isotope Beam Factory at RIKEN. A half-life of T_1/2 = 6.3(8) ms was measured for the new state which was tentatively assigned a spin/parity of (15^-). The experimental results are compared to shell model calculations performed using state-of-the-art realistic effective interactions and to the neighbouring nucleus ¹²⁹Cd. In the present experiment no evidence was found for the decay of a 18⁺ E6 spin-trap isomer, based on the complete alignment of the two-neutron and two-proton holes in the 0h_11/2 and the 0g_9/2 orbit, respectively, which is predicted to exist by the shell model. (authors)

[en] In this work, a novel imaging technique for the spatial calibration of a gamma camera is presented. The latter is aimed for the characterisation of the charge signals of 3D-position sensitive HPGe detectors. The characterisation method itself is based on pulse shape comparison (PSC) technique. The performance of the device is improved by implementing a gamma camera or position sensitive detector (PSD). This PSD consists of a uniform LYSO scintillating crystal optically glued to a crossed-wire position sensitive photomultiplier tube (PSPMT) from Hamamatsu. The individual multianode readout (IMAR) approach is used to improve its spatial resolution and to enlarge its field of view. A Compton scattering imaging technique is implemented to perform an accurate position calibration of the gamma camera.

[en] Conventionally HPGe detectors have been at the heart of a Gamma Detector Array, due to their excellent energy resolution (ΔE = 2 keV at the rate 1332 keV). However, the fast rise time from scintillator pulses have been exploited to perform timing measurements (Δt = 200 ps at 662 keV). Presently, LaBr3:Ce scintillators are attractive due to their excellent timing resolution as well as a reasonable energy resolution (ΔE = 20 keV at 662 keV). Therefore it is tempting to design a composite detector from a combination of HPGe and a LaBr3:Ce, which besides providing a fast timing also has a reasonable energy resolution as well as efficiency, and also allows possibilities for tracking