A new design of a detector plane of sub-millimetre thickness for an electromagnetic sampling calorimeter is presented. It is intended to be used in the luminometers LumiCal and BeamCal in future ...linear e
+
e
-
collider experiments. The detector planes were produced utilising novel connectivity scheme technologies. They were installed in a compact prototype of the calorimeter and tested at DESY with an electron beam of energy 1–5 GeV. The performance of a prototype of a compact LumiCal comprising eight detector planes was studied. The effective Molière radius at 5 GeV was determined to be (8.1 ± 0.1 (stat) ± 0.3 (syst)) mm, a value well reproduced by the Monte Carlo (MC) simulation (8.4 ± 0.1) mm. The dependence of the effective Molière radius on the electron energy in the range 1–5 GeV was also studied. Good agreement was obtained between data and MC simulation.
Investigation of the semiconductor detectors properties under neutron irradiation is very important for their practical application. High-resistivity gallium arsenide detectors (GaAs:Cr) were ...irradiated with various fast neutron fluences in range from 3.9×10n cm−2 to 3.7×1016 cm−2 at the IBR-2 reactor, FLNP, JINR. The neutron fluence was measured by placing silicon planar detectors at the measured points and measuring the 1 MeV (Si) equivalent fast neutron fluence. The charge collection efficiency and the current-voltage characteristics of irradiated detectors were measured, and their degradation after neutron irradiation was compared with the results obtained by irradiation with 21 MeV electrons.
In order to follow relative yields of
Bi(
) reactions, samples of natural bismuth were exposed in LINAC-200 bremsstrahlung beam at four different energies. Activities of eight obtained photonuclear ...reaction products with neutron multiplicity up to (
) were observed. Reaction yields normalized to the
Bi yield were calculated. The measured relative yields of
Bi isotopes were compared with the theoretical evaporation model based on the microscopically calculated level densities and with GEANT4 simulation.
The interest in using the radiation detectors based on high resistive chromium-compensated GaAs (GaAs:Cr) in high energy physics and others applied fields has been growing steadily due to its ...numerous advantages over others classical materials. High radiation hardness at room temperature stands out and needs to be systematically investigated. In this paper an experimental study of the effect of 20.9 MeV electrons generated by the LINAC-200 accelerator on some properties of GaAs:Cr based sensors is presented. In parallel, Si sensors were irradiated at the same conditions, measured and analyzed in order to perform a comparative study. The target sensors were irradiated with the dose up to 1.5 MGy. The current–voltage characteristics, resistivity, charge collection efficiency and their dependences on the bias voltage and temperature were measured at different absorbed doses. An analysis of the possible microscopic mechanisms leading to the observed effects in GaAs:Cr sensors is presented in the article.
Nowadays, the experiments related to High Energy Physics and others fields demand the use of detectors with greater radiation resistance, and the novel material GaAs:Cr has demonstrated excellent ...radiation hardness compared with other semiconductors. On the basis of evidence obtained in the JINR experiment with the use of 22 MeV electrons beam generated by the LINAC-800 accelerator, an analysis of electron radiation effects on GaAs:Cr and Si detectors is presented. The measured I-V characteristics showed a dark current increase with dose, and an asymmetry between the two branches of behaviors for all detectors. Analyzing the MIP spectra and CCE dose dependence measurements a deterioration process of detectors collection capacity with dose increase was found, although behaviors are somewhat different according to the detector type. The detailed explanation of these effects from the microscopic point of view appears in the text, and are generally linked to the generation of atomic displacement, vacancies and other radiation defects, modifying the energy levels structure of the target material. These changes affect the lifetime and concentration of the charge carriers, and other characteristics of the target material.
Abstract Nowadays, the experiments related to High Energy Physics and others fields demand the use of detectors with greater radiation resistance, and the novel material GaAs:Cr has demonstrated ...excellent radiation hardness compared with other semiconductors. On the basis of evidence obtained in the JINR experiment with the use of 22 MeV electrons beam generated by the LINAC-800 accelerator, an analysis of electron radiation effects on GaAs:Cr and Si detectors is presented. The measured I-V characteristics showed a dark current increase with dose, and an asymmetry between the two branches of behaviors for all detectors. Analyzing the MIP spectra and CCE dose dependence measurements a deterioration process of detectors collection capacity with dose increase was found, although behaviors are somewhat different according to the detector type. The detailed explanation of these effects from the microscopic point of view appears in the text, and are generally linked to the generation of atomic displacement, vacancies and other radiation defects, modifying the energy levels structure of the target material. These changes affect the lifetime and concentration of the charge carriers, and other characteristics of the target material.
En este trabajo la espectroscopia Raman ha sido empleada en la busqueda de evidencias del posible dano radiacional en un detector semiconductor de radiaciones de arseniuro de galio compensado con ...cromo al ser expuesto a un haz de electrones de 20 MeV. Los espectros Raman tomados antes y después de la irradiacion fueron deconvolucionados y su análisis mostraron que efectivamente en el material estaban teniendo lugar significativos procesos estimulados por la radiacion. Estos procesos conducen a la relajacion del estado tensional de la estructura, al incremento de la cristalinidad, y a la disminucion de la concentracion de portadores libres, que en el volumen estudiado de la muestra alcanza un 2.31 %. Los cambios observados deben estar relacionados con la generacion de defectos de tipo Frenkel en la subred del arsénico, y a cambios radiacionalmente estimulados en la cantidad y características de defectos preexistente de mayor complejidad. In this work, we use Raman spectroscopy to search for evidence of possible radiation damage in a chromium-compensated gallium arsenide semiconductor detector exposed to a 20 MeV electron beam. The Raman spectra measured before and after irradiation were deconvoluted, and their analysis shows that relevant processes stimulated by radiation take place in the material. These processes lead to the relaxation of the structure tensional state, the enhancement of crystallinity, and a decrease in the concentration of free carriers, which in the studied sample volume reaches 2.31 %. The observed changes could be related to the generation of new Frenkel-type defects in the arsenic sublattice, and to radiation-stimulated changes in the quantity and quality of pre-existing more complex defects.
This paper describes an iterative method of per-pixel energy calibration of hybrid pixel detectors with GaAs:Cr sensor and Timepix readout chip. A convolution of precisely measured spectra of ...characteristic X-rays of different metals with the resolution and the efficiency of the pixel detector is used for the calibration. The energy resolution of the detector is also measured during the calibration. The use of per-pixel calibration allows to achieve a good energy resolution of the Timepix detector with GaAs:Cr sensor: 8 and 13% at 60 and 20 keV, respectively.
This paper describes an iterative method of per-pixel energy calibration of hybrid pixel detectors with GaAs:Cr sensor and Timepix readout chip. A convolution of precisely measured spectra of ...characteristic X-rays of different metals with the resolution and the efficiency of the pixel detector is used for the calibration. The energy resolution of the detector is also measured during the calibration. The use of per-pixel calibration allows to achieve a good energy resolution of the Timepix detector with GaAs:Cr sensor: 8% and 13% at 60 keV and 20 keV, respectively.
PDF
