Search results for "Instrumentation"
showing 10 items of 4914 documents
Cubic boron nitride: A new prospective material for ultracold neutron application
2009
Abstract At the ultracold neutron (UCN) source of the TRIGA research reactor in Mainz, we have measured for the first time the material optical wall-potential of cubic boron nitride. The measurements were performed with a time-of-flight (TOF) spectrometer. The samples investigated had a wall-potential of ( 305 ± 15 ) neV . This value is in good agreement with the result extracted from neutron reflectometry data and theoretical expectations. Because of its high critical velocity for UCN and its good dielectric characteristics, cubic boron nitride coatings (isotopically enriched) will be useful for a number of applications in UCN experiments.
Time response of TOF spectrometer to light and heavy particles
2002
Comparing time of flight (TOF) values for α particles and fission fragments measured at different distances between the start- and stop detector we have obtained 60 ps as the upper limit for the TOF error resulting from the assumption of equal and linear time calibrations for both types of particles. While the 60 ps limit relates only to the specific spectrometer, the problem and the suggested verification technique are of general interest.
The GREAT spectrometer
2003
Abstract The GREAT spectrometer is designed to measure the decay properties of reaction products transported to the focal plane of a recoil separator. GREAT comprises a system of silicon, germanium and gas detectors optimised for detecting the arrival of the reaction products and correlating with any subsequent radioactive decay involving the emission of protons, α particles, β particles, γ rays, X-rays or conversion electrons. GREAT can either be employed as a sensitive stand-alone device for decay measurements at the focal plane, or used to provide a selective tag for prompt conversion electrons or γ rays measured with arrays of detectors deployed at the target position. A new concept of …
Electron-TOF-analyser for complete momentum analysis in photoemission from surfaces
2001
Abstract We present a new method for momentum-selective imaging by means of a time-of-flight (TOF) technique. The instrument employs a time- and space-resolving delayline detector in combination with a parabolic electrostatic field and a drift space. We use this kind of spectrometer, to raise the efficiency of experiments, which are total momentum resolved. The main difference to conventional photoemission experiments using a rotatable spectrometer is the simultaneous detection of all emitted photoelectrons. In addition to this feature, the angular distribution should be directly visible, to observe solid state symmetries. In order to facilitate these requirements, we use a delayline detect…
Efficiency studies for a tracking detector based on square 1.5m long scintillating fibers read out by SiPM
2009
Abstract A tracking detector based on 1.5 m long scintillating fibers is being developed for the electron arm of the KAOS spectrometer at the Mainz Microtron MAMI. Measurements on light attenuation, particle detection efficiencies and accidental coincidence rates with a prototype set-up using 2 × 2 mm 2 fibers read out by silicon photomultipliers (SiPM) are presented. The highest efficiency at the lowest accidental coincidence rate was reached for high trigger thresholds at the largest SiPM bias voltages. The influence of signal attenuation and dispersion on detection efficiencies is discussed. The results are in good agreement with a Monte Carlo model that was used to predict detector char…
Triple GEM tracking detectors for COMPASS
2002
The small area tracker of COMPASS, a high-luminosity fixed target experiment at CERN's SPS, includes a set of 20 large-size ($31\times 31\,\cm^2$) Gas Electron Multiplier (GEM) detectors. Based on gas amplification in three cascaded GEM foils, these devices permit to obtain high gain and good spatial resolution even at very high particle fluxes. A two-coordinate projective readout yields, for each track, highly correlated signal amplitudes on both projections, allowing to resolve multiple hits in high occupancy regions close to the central deactivated area of $5\,\cm$ diameter. At the same time the material exposed to the beam is minimized. Splitting the amplification in three cascaded stag…
Polarization phenomena in Al/p-CdTe/Pt X-ray detectors
2013
Over the last decades, CdTe detectors are widely used for the development of room temperature X-ray and gamma ray spectrometers. Typically, high resolution CdTe detectors are fabricated with blocking contacts (indium, aluminum) ensuring low leakage currents and high electric field for optimum charge collection. As well known, time instability under bias voltage (termed as polarization) is the major drawback of CdTe diode detectors. Polarization phenomena cause a progressive degradation of the spectroscopic performance with time, due to hole trapping and detrapping from deep acceptors levels. In this work, we studied the polarization phenomenon on new Al/p-CdTe/Pt detectors, manufactured by …
Study of background characteristics of a low-level HPGe spectrometer with passive shielding in various configurations
1997
Abstract A low-background germanium spectrometer has been investigated with different combinations of shielding materials in two locations at ground level. In particular, seven shielding configurations have been tested in a room with thick walls and ceiling. The background components, peaks and continuum in the 50–2600 keV energy region, obtained in the several experimental conditions are reported and discussed.
Performance of HPGe detectors in high magnetic field
2006
A new generation of high-resolution hypernuclear gamma$-spectroscopy experiments with high-purity germanium detectors (HPGe) are presently designed at the FINUDA spectrometer at DAPhiNE, the Frascati phi-factory, and at PANDA, the antiproton proton hadron spectrometer at the future FAIR facility. Both, the FINUDA and PANDA spectrometers are built around the target region covering a large solid angle. To maximise the detection efficiency the HPGe detectors have to be located near the target, and therefore they have to be operated in strong magnetic fields B ~ 1 T. The performance of HPGe detectors in such an environment has not been well investigated so far. In the present work VEGA and EURO…
Performance enhancements of compound semiconductor radiation detectors using digital pulse processing techniques
2011
Abstract The potential benefits of using compound semiconductors for X-ray and gamma ray spectroscopy are already well known. Radiation detectors based on high atomic number and wide band gap compound semiconductors show high detection efficiency and good spectroscopic performance even at room temperature. Despite these appealing properties, incomplete charge collection is a critical issue. Generally, incomplete charge collection, mainly due to the poor transport properties of the holes, produces energy resolution worsening and the well known hole tailing in the measured spectra. In this work, we present a digital pulse processing (DPP) system for high resolution spectroscopy with compound …