Search results for "Instrumentation"
showing 10 items of 4914 documents
Gain stabilization and noise minimization for SiPMs at cryogenic temperatures
2018
Abstract The performance of solid-state photon detectors such as avalanche photodiodes or silicon photomultipliers (SiPMs) is strongly affected by temperature. Important device characteristics for the detection of low light levels or single photons are photon detection efficiency, dark noise, and gain. In the present work the C-series SiPMs from SensL was characterized in cryogenic environments. At 77 K the SiPMs proved to be an excellent choice for single photon detection and an operation point with minimum noise contributions was found. At 4 K the performance was degraded, exhibiting a smaller gain and a larger noise.
Response of BGO detectors to photons of 3–50 MeV energy
1993
Abstract The response of an array of 7 hexagonal BGO detectors each 7.5 cm long (6.7 radiation lengths) with 3.6 cm side-to-side distance was measured using monochromatic photons from the tagged-photon facility at the electron accelerator MAMI A at Mainz. The experimental spectra of the deposited energy for a single detector and for the array of seven modules compare very well with the predictions of Monte Carlo shower simulations using the code GEANT3. Significant improvement of the energy resolution is observed for the summed energy spectra compared to the resolution of a single module. This improvement deteriorates at higher photon energies because the length of the detector is not suffi…
AX-PET: A novel PET concept with G-APD readout
2012
Abstract The AX-PET collaboration has developed a novel concept for high resolution PET imaging to overcome some of the performance limitations of classical PET cameras, in particular the compromise between spatial resolution and sensitivity introduced by the parallax error. The detector consists of an arrangement of long LYSO scintillating crystals axially oriented around the field of view together with arrays of wave length shifter strips orthogonal to the crystals. This matrix allows a precise 3D measurement of the photon interaction point. This is valid both for photoelectric absorption at 511 keV and for Compton scattering down to deposited energies of about 100 keV. Crystals and WLS s…
Measurement of the response of Silicon Photomultipliers from single photon detection to saturation
2019
Abstract The development of Silicon Photomultipliers (SiPM) is very dynamic and a large variety of types exists. Important SiPM characteristics include the size and number of pixels, the gain, the photon detection efficiency (PDE), the recovery time, and correlated noise. SiPMs are particularly suitable for single-photon detection and low-intensity exposures. For photon numbers (PDE corrected) reaching the number of pixels, however, the sensors saturate. In this work, we present comprehensive response measurements for state-of-the-art SiPMs using an experimental setup based on a tunable picosecond laser. Several models are applied to the measured response curves, taking particularly correla…
Recent progress with microchannel-plate PMTs
2020
Abstract Microchannel-plate (MCP) PMTs were identified as the only suitable photon sensors for the two DIRC detectors of the PANDA experiment at FAIR. As the long-standing aging problem of MCP-PMTs was recently overcome by coating the MCP pores with an atomic layer deposition (ALD) technique, further improved 2 ″ MCP-PMTs were investigated. The best PHOTONIS device has reached a lifetime of > 20 C/cm2 integrated anode charge without any sign of aging. Also the newly developed 2 ″ MCP-PMTs of Hamamatsu are maturing and are usable in high rate environments. The status of our long-term lifetime measurements and the performance parameters of the currently most advanced ALD-coated MCP-PMTs from …
Lateral diffusion estimation in fully depleted thick CCD using flat field image analysis
2011
Abstract In thick fully depleted CCDs charge carrier transport from the back window to the gates is accompanied by charge diffusion. Lateral diffusion smooths out density variations of the incoming photon flux by redistributing charges spatially. This creates short range positive correlations in recorded amplitudes. Pixel-to-pixel amplitude variations can also be caused by pixel size and quantum efficiency variations. Pixel size variations result in short range negative correlations. Our study shows that the characteristic diffusion width can be extracted from flat field data. The study was performed on fully depleted, thick CCDs produced in a technology study for the Large Synoptic Survey …
New experimental method for investigation of the nucleon polarizabilities
2010
Abstract At the continuous wave (cw) Superconducting Darmstadt Electron Linear Accelerator S-DALINAC, a new method has been developed for the determination of the electric ( α ¯ ) and magnetic ( β ¯ ) polarizabilities of the proton and the deuteron. For that purpose the energy and angular dependence of the differential cross-section for elastic γ p and γ d scattering of bremsstrahlung photons in the energy range between 20 and 100 MeV is measured by detecting the recoiling proton (deuteron) in coincidence with the scattered bremsstrahlung photon. α ¯ and β ¯ are then found by means of a best fit to a theoretical description of the scattering cross-section with these quantities as open param…
Channeling experiments with sub-GeV electrons in flat silicon single crystals
2015
Abstract Various planar channeling experiments, performed at the Mainz Microtron MAMI with electrons at silicon single crystals, have been reanalyzed. Two types of signals have been employed. The low energy loss signal originates from emission of channeling radiation in the energy domain between 0.4 and 9 MeV while the high energy loss signal from electrons which have lost about 50% of their primary energy by emission of bremsstrahlung photons. The (1 1 0) planar channeling data, taken at a beam energy of 855 MeV with the former signal, can well be described on the basis of the solution of the classical Fokker–Planck equation. The measurements with the latter signal at beam energies between…
Discrimination of LINAC photon and sunlight contributions in watch glass analyzed by means of thermoluminescence
2012
Abstract The research described in this paper shows how to extract from the glow curves of watch glasses exposed to LINAC photons and sunlight a contribution sensitive to LINAC photons dose. As first step, the dependence of the TL signal due to sunlight on the exposure duration was studied and a signal saturation was observed after about 20 weeks. The comparison of TL signals due to solar light and to LINAC photons highlights a partial overlap of the two signals. Here, two different analysis procedures of glow curves (general order kinetics deconvolution and principal components analysis) are reported to point out components which depend differently on LINAC photon radiation dose. For both …
A compact Time Projection Chamber for the Crystal Ball
2016
Abstract We report on a development of a compact Time Projection Chamber with triple Gas Electron Multiplier readout to replace the current tracking detector in the Crystal Ball/TAPS Experiment at the A2 Tagged Photon Facility at MAMI in Mainz, Germany. Challenges are the limitations in size and the absence of a longitudinal magnetic flied.