Search results for "Anode"
showing 10 items of 317 documents
Spectroscopic response of a CdZnTe multiple electrode detector
2007
Abstract The spectroscopic performances of a CdZnTe detector (crystal size: 5×5×0.9 mm 3 ) with five electrodes (cathode, anode and three steering electrodes) were studied. The anode layout, which consists of a circular electrode ( φ =80 μm) surrounded by two ring electrodes (gap=100 μm; radial width Δ r =100 μm) and by one electrode that extends to the edge of the crystal, is mostly sensitive to the electron carriers, overcoming the well known effect of the hole trapping in the measured spectra. We report on the spectroscopic response of the detector at different bias voltages of the electrodes and at various photon energies ( 109 Cd, 241 Am and 57 Co sources). The CdZnTe detector exhibits…
Nanoscale X-ray detectors based on individual CdS, SnO2 and ZnO nanowires
2021
Abstract The development of nanoscale X-ray sensors is of crucial importance to achieve higher spatial resolution in many X-ray-based techniques playing a key role in materials science, healthcare, and security. Here, we demonstrate X-ray detection using individual CdS, SnO 2 , and ZnO nanowires (NWs). The NWs were produced via vapor–liquid–solid technique and characterized using X-ray diffraction, scanning, and transmission electron microscopy . Electrical measurements were performed under ambient conditions while exposing two-terminal NW-based devices to X-rays generated by a conventional tungsten anode X-ray tube. Fast and stable nanoampere-range X-ray beam induced current (XBIC) in resp…
Resolution changes of MCP-PMTs in magnetic fields
2016
Micro-channel plate photomultiplier tubes (MCP-PMTs) are chosen in many applications that have to cope with strong magnetic fields. The DIRC detectors of the PANDA experiment plan to employ them as they show excellent timing characteristics, radiation hardness, relatively low dark count rates and sufficient lifetime. This article mainly focuses on the performance of the position reconstruction of detected photons. Two different MCP-PMTs with segmented anode geometries have been tested in magnetic fields of different strengths. The variation of their performance has been studied. The measurements show improved position resolution and image shifts with increasing magnetic field strength.
Lifetime of MCP-PMTs and other performance features
2018
The ANDA experiment at FAIR will use DIRC detectors for the separation of hadrons. The compactness of the ANDA detector requires the image planes of these detectors to be placed inside the magnetic field of the solenoid. Due to this and other boundary conditions MCP-PMTs were identified as the only suitable photon sensors. Until recently the major obstacle for an application of MCP-PMTs in high rate experiments like ANDA were serious aging problems which led to damage at the photo-cathode and a fast declining quantum efficiency as the integrated anode charge (IAC) increased. With new countermeasures against the aging, in particular due to the application of an atomic layer deposition (ALD) …
Spatial distribution of air kerma rate and impact of accelerating voltage on the quality of an ultra soft X-ray beam generated by a cold cathode tube…
2015
Abstract Ultrasoft X-ray characteristic aluminum K alpha line (Al Kα with energy of 1.5 keV) is used in radiobiological experiments to study the effect of radiation on biological matter. A simple method to generate a continuous beam of those X-ray radiations is to bombarding an aluminum target with accelerated electrons using high voltage (HV). In this work, by varying the HV we study the characteristics of a photon beam generated by means of a cold cathode transmission X-ray tube. The anode is a thin (16 μm) aluminum foil supported by a copper grid. The spatial distribution of air kerma is measured using gafchromic films of HD-810 calibrated with a parallel plate free-air ionization chambe…
Characterization of Al-Schottky CdTe detectors
2011
In the last decades, great efforts are being devoted to the development of CdTe detectors for high resolution X-ray and gamma ray spectroscopy. Recently, new rectifying contacts based on aluminum (Al) are very appealing in the development of CdTe detectors with low leakage currents and anode pixellization. In this work, we report on preliminary results of electrical and spectroscopic investigations on Schottky CdTe diode detectors (4.1 × 4.1 × 0.75 and 4.1 × 4.1 × 2 mm3) with Au/Ti/Al/CdTe/Pt electrode configuration. The detectors are characterized by very low leakage currents even at room temperature (26 pA at 25 °C under a bias voltage of −100 V for the 2 mm thick detector). Polarization …
Electrical Characterization of CdTe pixel detectors with Al Schottky anode
2014
Abstract Pixelated Schottky Al/p-CdTe/Pt detectors are very attractive devices for high-resolution X-ray spectroscopic imaging, even though they suffer from bias-induced time instability (polarization). In this work, we present the results of the electrical characterization of a (4×4) pixelated Schottky Al/p-CdTe/Pt detector. Current–voltage ( I–V ) characteristics and current transients were investigated at different temperatures. The results show deep levels that play a dominant role in the charge transport mechanism. The conduction mechanism is dominated by the space charge limited current (SCLC) both under forward bias and at high reverse bias. Schottky barrier height of the Al/CdTe con…
Polarographic determination of glycine with a dropping copper amalgam electrode
1975
The anodic oxidation of a dropping copper amalgam electrode in presence of dilute solutions of glycine in 0.50 M NaClO4 has been studied. An anodic wave at −0.28V (SCE) is observed, yielded by diffusion of glycinate anion in the solution towards the electrode surface. The wave-heights increase with the glycinate concentration (function of glycine concentration and pH value) until the anodic oxidation is controlled by the metal diffusion into mercury. The effect of pH is interpreted by attributing it to the depolarizer effects at glycinate anion even though the zwitterion is present in much larger concentrations. The applicability of anodic oxidation of a dropping copper amalgam electrode in…
Electrochemical reactions with adsorption of the reactants and electrosorption. Simple analytical solutions for a Henry isotherm
1998
Abstract A theoretical treatment of an electrochemical reaction O + ne− R with adsorption of the reactants is presented when the adsorption, at equilibrium, obeys a Henry isotherm. A simple analytical solution, valid for any degree of adsorption of O and or R, is established for a polarographic wave. In LSV, for slow sweep rates and weak adsorption, both the cathodic and anodic peaks have a ‘diffusional’ character; for high sweep rates and strong adsorption, they are both of a ‘surface’ nature. In the intermediate case, one peak has a ‘diffusional’ character (deposition process), while the other is of a ‘surface’ nature (redissolution process). Expressions of the peak potentials are given i…
Cathodic abatement of Cr(VI) in water by microbial reverse-electrodialysis cells
2015
Abstract For the first time a microbial reverse electrodialysis cell (MRC) was used for the treatment of water contaminated by Cr(VI). It has been recently shown that both inorganic and organic pollutants can be removed by reverse electrodialysis processes (RED) using water with different salinity without the supply of electric energy. However, a high number of membrane pairs is usually necessary for the treatment of wastewater by RED. Here, it was showed that a lower number of membranes can be used by the utilization of a MRC (i.e., a RED cell with a biotic anode) for such purposes. Indeed, the abatement of Cr(VI), chosen as model pollutant, was successfully achieved by cathodic reduction …