Blanco, A., Belver, D., Cabanelas, P., Diaz, J., Fonte, P., Garzon, J. A., et al. (2012). RPC HADES-TOF wall cosmic ray test performance. Nucl. Instrum. Methods Phys. Res. A, 661, S114–S117.
Abstract: In this work we present results concerning the cosmic ray test, prior to the final installation and commissioning of the new Resistive Plate Chamber (RPC) Time of Flight (TOF) wall for the High-Acceptance DiElectron Spectrometer (HADES) at GSI. The TOF wall is composed of six equal sectors, each one constituted by 186 individual 4-gaps glass-aluminium shielded RPC cells distributed in six columns and 31 rows in two partially overlapping layers, covering an area of 1.26 m(2). All sectors were tested with the final Front End Electronic (FEE) and Data AcQuisition system (DAQ) together with Low Voltage (LV) and High Voltage (HV) systems. Results confirm a very uniform average system time resolution of 77 ps sigma together with an average multi-hit time resolution of 83 ps. Crosstalk levels below 1% (in average), moderate timing tails along with an average longitudinal position resolution of 8.4 mm sigma are also confirmed.
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Goel, N., Domingo-Pardo, C., Habermann, T., Ameil, F., Engert, T., Gerl, J., et al. (2013). Characterisation of a symmetric AGATA detector using the gamma-ray imaging scanning technique. Nucl. Instrum. Methods Phys. Res. A, 700, 10–21.
Abstract: The imaging scanning technique for the characterisation of large volume, highly segmented, HPGe detectors is demonstrated by comparing the measured spatial response of a symmetric AGATA crystal versus the theoretical calculations obtained with the Multi-Geometry Simulation (MGS) code. The signal rise-times measured as a function of the gamma-ray interaction positions, in both coaxial and planar regions of the detection volume, are presented and confronted with the expected behaviour obtained via MGS. The transition in charge carrier transport behaviour as a function of the depth is studied for the region of the complex electric field. In general, a fairly good agreement between theory and experiment is obtained. Only systematic deviations between simulation and measurement are observed in the critical front part of the AGATA detector. They may be ascribed to a non-linear impurity concentration profile of the germanium crystal.
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Esteve, R., Toledo, J., Monrabal, F., Lorca, D., Serra, L., Mari, A., et al. (2012). The trigger system in the NEXT-DEMO detector. J. Instrum., 7, C12001–9pp.
Abstract: NEXT-DEMO is a prototype of NEXT (Neutrino Experiment with Xenon TPC), an experiment to search for neutrino-less double beta decay using a 100 kg radio-pure, 90 % enriched (136Xe isotope) high-pressure gaseous xenon TPC with electroluminescence readout. The detector is based on a PMT plane for energy measurements and a SiPM tracking plane for topological event filtering. The experiment will be located in the Canfranc Underground Laboratory in Spain. Front-end electronics, trigger and data-acquisition systems (DAQ) have been built. The DAQ is an implementation of the Scalable Readout System (RD51 collaboration) based on FPGA. Our approach for trigger is to have a distributed and reconfigurable system in the DAQ itself. Moreover, the trigger allows on-line triggering based on the detection of primary or secondary scintillation light, or a combination of both, that arrives to the PMT plane.
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Clinthorne, N., Brzezinski, K., Chesi, E., Cochran, E., Grkovski, M., Grosicar, B., et al. (2013). Silicon as an unconventional detector in positron emission tomography. Nucl. Instrum. Methods Phys. Res. A, 699, 216–220.
Abstract: Positron emission tomography (PET) is a widely used technique in medical imaging and in studying small animal models of human disease. In the conventional approach, the 511 keV annihilation photons emitted from a patient or small animal are detected by a ring of scintillators such as LYSO read out by arrays of photodetectors. Although this has been successful in achieving similar to 5 mm FWHM spatial resolution in human studies and similar to 1 mm resolution in dedicated small animal instruments, there is interest in significantly improving these figures. Silicon, although its stopping power is modest for 511 keV photons, offers a number of potential advantages over more conventional approaches including the potential for high intrinsic spatial resolution in 3D. To evaluate silicon in a variety of PET “magnifying glass” configurations, an instrument was constructed that consists of an outer partial-ring of PET scintillation detectors into which various arrangements of silicon detectors are inserted to emulate dual-ring or imaging probe geometries. Measurements using the test instrument demonstrated the capability of clearly resolving point sources of Na-22 having a 1.5 mm center-to-center spacing as well as the 1.2 mm rods of a F-18-filled resolution phantom. Although many challenges remain, silicon has potential to become the PET detector of choice when spatial resolution is the primary consideration. (C) 2012 Elsevier B.V. All rights reserved.
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AGATA Collaboration(Crespi, F. C. L. et al), & Gadea, A. (2013). Response of AGATA segmented HPGe detectors to gamma rays up to 15.1 MeV. Nucl. Instrum. Methods Phys. Res. A, 705, 47–54.
Abstract: The response of AGATA segmented HPGe detectors to gamma rays in the energy range 2-15 MeV was measured. The 15.1 MeV gamma rays were produced using the reaction d(B-11,n gamma)C-12 at E-beam=19.1 MeV, while gamma rays between 2 and 9 MeV were produced using an Am-Be-Fe radioactive source. The energy resolution and linearity were studied and the energy-to-pulse-height conversion resulted to be linear within 0.05%.Experimental interaction multiplicity distributions are discussed and compared with the results of Geant4 simulations. It is shown that the application of gamma-ray tracking allows a suppression of background radiation caused by n-capture in Ge nuclei. Finally the Doppler correction for the 15.1 MeV gamma line, performed using the position information extracted with Pulse-shape analysis is discussed.
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