[show abstract][hide abstract] ABSTRACT: For the first time a segmented n-type HPGe detector was operated directly submerged in liquid nitrogen over a long period. As this kind of detector is envisioned to be used in GERDA phase II, it was operated with a low mass signal cable with snap-contacts and mounted in a low-mass copper holder. The detector performance was stable over 146 days, indicating that neither detector nor contacts deteriorated.
Journal of Instrumentation 01/2009; · 1.66 Impact Factor
[show abstract][hide abstract] ABSTRACT: The first true coaxial 18-fold segmented n-type HPGe prototype detector produced by Canberra-France for the GERDA neutrinoless double beta-decay project was tested both at Canberra-France and at the Max-Planck-Institut für Physik in Munich. The main characteristics of the detector are given and measurements concerning detector properties are described. A novel method to establish contacts between the crystal and a Kapton cable is presented.
Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment 02/2007; · 1.14 Impact Factor
[show abstract][hide abstract] ABSTRACT: For high throughput and energy-resolution fluorescence x-ray absorption spectroscopy (XAS), a novel Ge pixel array detector (PAD) with 100 segments has been developed. Two sets of PAD having different thickness values, i.e., 10 mm (no 1) and 7.5 mm (no 2), were constructed and installed at Spring-8 (BL10XU) and Photon Factory (BL13B). Using a monolithic approach, a nearly perfect packing fraction (>88%) and commission rate (99%) were achieved, resulting in a significant improvement over a previous Ge multi-element detector. In the present PAD design, each segment is square-shaped having an active area of 22 mm2. The average energy resolution at 5.9 keV was 220 eV (6 μs shaping time) and 240 eV (0.5 μs) in a high throughput mode. High efficiency x-ray detection over a wide energy range (5–60 keV) was confirmed. The present electronics-limited throughput maximum is 100 kcps per channel or 10 MHz in total. We will describe unconventional applications in fluorescence XAS demonstrating the capability of PAD. The recent in-situ XAS study under laser light required a small amount of specimen less than 10-3 g.
Physica Scripta 11/2006; 2005(T115):1004. · 1.03 Impact Factor
[show abstract][hide abstract] ABSTRACT: A Ge pixel array detector with 100 segments was applied to fluorescence X-ray absorption spectroscopy, probing the local structure of high-temperature superconducting thin-film single crystals (100 nm in thickness). Independent monitoring of pixel signals allows real-time inspection of artifacts owing to substrate diffractions. By optimizing the grazing-incidence angle theta and adjusting the azimuthal angle phi, smooth extended X-ray absorption fine structure (EXAFS) oscillations were obtained for strained (La,Sr)2CuO4 thin-film single crystals grown by molecular beam epitaxy. The results of EXAFS data analysis show that the local structure (CuO6 octahedron) in (La,Sr)2CuO4 thin films grown on LaSrAlO4 and SrTiO3 substrates is uniaxially distorted changing the tetragonality by approximately 5 x 10(-3) in accordance with the crystallographic lattice mismatch. It is demonstrated that the local structure of thin-film single crystals can be probed with high accuracy at low temperature without interference from substrates.
[show abstract][hide abstract] ABSTRACT: For high throughput/energy-resolution fluorescence X-ray detection in X-ray absorption spectroscopy (XAS), a novel Ge pixel array detector (PAD) with 100 segments has been developed. Using a monolithic approach, a high packing density (88%) with nearly perfect commission rate (99%) were achieved, resulting in a dramatic improvement in packing density compared to the close-packed multi-element detector (57%). Two types of PAD was built with the pixel thickness of 7.5 and 10 mm. Each segment has an active area of 22 mm2. The average energy resolution at 5.9 keV was ca. 220 eV (6 μs shaping time) and 240 eV (0.5 μs shaping time). High efficiency in X-ray detection in a wide energy range (5–60 keV) was confirmed. The present data acquisition system, CAMAC-based hybrid electronics, is capable of independent energy-analysis and recording all channels with a maximum 100 kcps per channel or 10 MHz in total. Elimination of elastic and inelastic scattering improved the systematic error in XAS, as demonstrated by an XAS application to a photo-induced phase transition.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. 01/2003;
[show abstract][hide abstract] ABSTRACT: Various sectored or segmented detectors (single or composite crystals) used for gamma spectroscopy will be discussed in this paper. In particular, their performance (efficiency and energy resolution) are thus reported.
[show abstract][hide abstract] ABSTRACT: This paper discusses the development and the realisation of an encapsulated Ge detector. The properties of a first prototype detector are; relative efficiency εrel = 21.4%; energy resolution: ΔEγ(1.33MeV) = 2.10 keV and ΔEγ(122 keV) = 1.10 keV. The encapsulation technology offers advantages; several encapsulated Ge detectors can be mounted closely packed in a cryostat, all electronic parts of the first preamplifier stage are accessible and induced radiation damage of the Ge crystal can be annealed in a standard furnace.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. 01/1996;
[show abstract][hide abstract] ABSTRACT: The energy resolution of a n-type HPGe detector has been measured as function of the operating temperature before and after inducing radiation damage by neutrons from a fusion evaporation reaction. The aim of the investigation was to determine an appropriate operating temperature for Ge multidetector arrays. In the undamaged condition the leakage current due to thermal production of charge carriers limits the operating temperature to below 125 K. With neutron induced trapping levels the operating temperature has to be decreased to below 100 K because of thermal activation of trapping levels and defect migrations.
Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment 07/1993; 332(s 1–2):215–219. · 1.14 Impact Factor
[show abstract][hide abstract] ABSTRACT: The aim of the EUROBALL project is the development of γ-ray detectors with substantially improved qualities, and the realization of large solid angle arrays, in particular of 4π spectrometers employing these detectors. This article especially focusses on the development of a Cluster detector consisting of seven large hexagonal tapered and encapsulated Ge detectors which are surrounded by a common BGO anti-Compton shield. First results of the properties of a hexagonal tapered Ge detector and of an encapsulated Ge detector are presented.
Progress in Particle and Nuclear Physics. 01/1992;
[show abstract][hide abstract] ABSTRACT: Background spectra of several Ge spectrometers have been recorded in a deep underground laboratory located in the Frejus tunnel. The results show that an alpha ray induced background from the 210Pb decay is observed. A possible explanation could be related to the adsorption of the Rn gas on the surfaces of the Ge crystal and/or other parts during the assembly of the spectrometer.
Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment - NUCL INSTRUM METH PHYS RES A. 01/1986; 252:87-90.
[show abstract][hide abstract] ABSTRACT: Various Ge(Li) detectors showing trapping effects (low energy tailing for an applied field of 103 V/cm) with uniform Â¿-ray irradiation have been studied using a collimated beam of 137Cs Â¿-rays. The following parameters have been determined : velocity, mobility, drift length and carrier lifetime. For many samples, a good agreement between experimental measurements of charge collection efficiency with the position of irradiation and calculated curves is obtained de monstrating that the trap distribution is uniform. The carrier velocities and mobilities are practically not modified in the samples showing trapping effects, but the drift lengths are lowered and, as a consequence, the carrier lifetimes. Various-measurements including infrared transmission spectra, etch-pit distributions, electron lifetimes have been made on the starting P-type crystals. Results are presented showing a valuable correlation between the electron lifetimes measured at 77Â°K by the pulse charge method and detector performance.
IEEE Transactions on Nuclear Science 07/1970; · 1.22 Impact Factor