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Radiation Detectors (radiation + detector)
Selected AbstractsPurification and crystal growth of TlBr for application as a radiation detectorCRYSTAL RESEARCH AND TECHNOLOGY, Issue 10 2004I. B. Oliveira Abstract Thallium bromide is a semiconductor compound with high atomic number and density. It has a CsCl-type simple cubic crystal structure and it is non-hygroscopics. The TlBr crystals are relatively soft with a knoop hardness number of 12. In this work, the TlBr commercial powder was purified by zone refining and the purest material section was used for crystal growth by Bridgman method. Efforts have been concentrated on the purification of the TlBr. The purification efficiency has been evaluated (NAA and ICP-MS) by impurities reduction results after zone refining passes. The crystalline quality was evaluated by X-ray diffraction. The characterized TlBr crystal as a detector has shown good response to gamma radiation. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Atomic Structure and Electrical Properties of In(Te) Nanocontacts on CdZnTe(110) by Scanning Probe MicroscopyADVANCED FUNCTIONAL MATERIALS, Issue 2 2010Gili Cohen-Taguri Abstract Understanding complex correlations between the macroscopic device performance (largely dependent on the character of the metal,semiconductor contact) and the metallurgy of contact formation on the atomic level in cadmium zinc telluride (CdZnTe) radiation detectors remains a formidable challenge. In this work, an effort towards bridging that macro,nano knowledge gap is made by conducting a series of controlled experiments aimed at correlating electrical properties of the In contact to n-type CdZnTe(110) surface with the step-by-step process of contact formation. This can only be achieved by using high spatial resolution techniques, capable of conducting highly localized measurements on the nano- and sub-nanoscale, such as scanning probe microscopy. Scanning tunneling microscopy is used in situ to monitor the behavior of various In atom coverages on an atomically flat and ordered CdZnTe surface under well-controlled molecular beam epitaxial conditions in ultra-high vacuum. Electrical derivatives of atomic force microscopy are used to measure the electrical contact properties, such as contact potential difference and spreading resistance in torsion resonance tunneling mode. It is concluded that In atoms preferentially reacted with Te atomic-rows already at room temperature, forming nanometric patches of indium,telluride Schottky-type contacts. The methods developed in this study, in terms of both nanocontact fabrication and characterization (especially in terms of electrical properties) should benefit basic and applied research of any metal,semiconductor system. [source] Position-sensitive radiation detectors made of single crystal CVD diamondPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 9 2009M. Pomorski Abstract Based on a single crystal chemical vapour deposition (scCVD) diamond plate a position sensitive detector [position sensitive detection position sensitive detector (PSD)] has been fabricated. The ,9,mm2 sensing area of the detector consists of a diamond-like carbon (DLC) thin film, in the form of a plane-pad resistive electrode layer deposited on the scCVD surface. The 1D position information is obtained from the resistive charge division between two collecting electrodes located at the extremities of the DLC sensing electrode. The detector properties have been tested using a 241Am ,-particles source. The timing characteristics of the device were probed using broad-band (BB) electronics: the signal formation does not exceed 30,ns, thus detector operation with a negligible ballistic effect is possible at high rates approaching 107,particles/s. The linearity and position resolution of the device was measured using low-noise charge-sensitive (CS) electronics: the position resolution reaches 30,µm (,), the deviation from linearity remain below 2% in the full range of the detector sensing area. [source] Analysis of traps in CVD diamond films through thermal depumping of nuclear detectorsPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 11 2004A. Balducci Abstract Carrier free paths in Chemical Vapour Deposition (CVD) diamond films depend on the presence of traps, which therefore strongly affect the performance of those CVD diamond based devices which rely on the electronic properties of the material, like radiation detectors. For the same reason, these devices can in turn be used as tools to study carrier dynamics. It is well known that some traps may be saturated by pre-irradiation with ionizing radiation (e.g. ,-particles), a process called "pumping" or "priming". Not all traps behave in the same way. Due to the large bandgap of diamond, both shallow (not affected by pumping) and deep traps for electrons and holes may exist. We measured, using 5.5 MeV 241Am ,-particles, the response of high quality CVD diamond based detectors after successive annealing steps performed at selected temperatures. The analisys of the decay of the detector efficency with annealing time at several temperatures allows a quantitative evaluation of the activation energy of these defects. Two main trapping centres connected to the pumping process were found, both related to holes, having activation energies of about 1.6 eV and 1.3 eV respectively. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] | ||||||||||