The MAGIC Cerenkov telescope has observed very high energy (VHE) g-ray emission from the active galactic nucleus 1ES 1959+650 during 6 hr in 2004 September and October. The observations were carried ...out alternating with observations of the Crab Nebula, whose data were used as a reference source for optimizing g -ray/hadron separation and for flux comparison. The data analysis shows VHE g-ray emission of 1ES 1959+650 with 68 s significance, at a time of low activity in both optical and X-ray wavelengths. An integral flux above 6180 GeV of about 20% that of the Crab Nebula was obtained. The light curve, sampled over 7 days, shows no significant variations. The differential energy spectrum between 180 GeV and 2 TeV can be fitted with a power-law of index -2.72 c 0.14. The spectrum is consistent with the slightly steeper spectrum seen by HEGRA at higher energies, also during periods of low X-ray activity.
Multi-cell avalanche photodiodes (APDs) operating in Geiger mode have been shown to be a very promising alternative to photomultiplier tubes for the detection of single photons at room temperature. ...Like a photomultiplier they have high gain and a fast rise time and they are insensitive to pickup. Beyond it they operate in high magnetic fields, are compact and need a relatively low bias voltage. It is expected that the MOS production technique makes them cheap. Recently PSI and Hamamatsu Photonics worked together for the development of a radiation-hard APD for CMS ECAL and had very good success. The development continued based on a similar design for a photon counting multielement Geiger-mode APD with an area of 1×1
mm
2. The properties of this device have been measured and will be reported.
Radiation hard avalanche photodiodes for the CMS detector Antunovic, Z.; Britvitch, I.; Deiters, K. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
01/2005, Letnik:
537, Številka:
1-2
Journal Article
Recenzirano
Odprti dostop
The avalanche photodiodes, developed by Hamamatsu Photonics in collaboration with CMS, which are to be used to read out the lead tungstate crystals in the barrel part of the CMS electromagnetic ...calorimeter, are described. The procedures taken to ensure their long-term reliability in the radiation environment expected in CMS are outlined, as well as the studies made to verify the very high reliability required.
The Next Generation Radiation Monitor- NGRM Desorgher, L.; Hajdas, W.; Britvitch, I. ...
2013 IEEE Nuclear Science Symposium and Medical Imaging Conference (2013 NSS/MIC),
10/2013
Conference Proceeding
The ESA Next Generation Radiation Monitor (NGRM) will be the successor of the ESA Standard Radiation Environment Monitor (SREM) that is still measuring near-Earth and interplanetary space radiation ...environment onboard 6 different spacecrafts. NGRM will measure protons from 2 MeV up to 200 MeV, electrons from 100keV up to 7MeV, as well as LET spectrum of ions. Compared to SREM, NGRM will provide a much better energy resolution, will be smaller (<;1L), lighter (<;1kg) and consume less energy (<;1W). In this paper we describe the detection concept of the NGRM and present the detailed Monte Carlo analysis of the performance of the NGRM detector system.
The atmospheric Cherenkov gamma-ray telescope MAGIC, designed for a low-energy threshold, has detected very-high-energy gamma rays from a giant flare of the distant Quasi-Stellar Radio Source (in ...short: radio quasar) 3C 279, at a distance of more than 5 billion light-years (a redshift of 0.536). No quasar has been observed previously in very-high-energy gamma radiation, and this is also the most distant object detected emitting gamma rays above 50 gigaelectron volts. Because high-energy gamma rays may be stopped by interacting with the diffuse background light in the universe, the observations by MAGIC imply a low amount for such light, consistent with that known from galaxy counts.
Hamamatsu APD for CMS ECAL: quality insurance Bailleux, D.; Britvitch, I.; Deiters, K. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
02/2004, Letnik:
518, Številka:
1
Journal Article
Recenzirano
The Hamamatsu Photonics S8148 large area Avalanche Photo Diodes (APD) were designed for the crystal electromagnetic calorimeter of the CMS setup at LHC in a close collaboration of Hamamatsu Photonics ...and CMS APD group (PSI, Northeastern University and University of Minnesota). All essential parameters of these devices are controlled by the producer and are fairly stable during the mass production, except the radiation hardness. To insure 99.9% reliability of APDs in the radiation hard environment of LHC, the CMS APD group had to invent a dedicated screening procedure. The details of this procedure and some results of the screening are discussed.
One fundamental question about pulsars concerns the mechanism of their pulsed electromagnetic emission. Measuring the high-end region of a pulsar's spectrum would shed light on this question. By ...developing a new electronic trigger, we lowered the threshold of the Major Atmospheric γ-ray Imaging Cherenkov (MAGIC) telescope to 25 giga--electron volts. In this configuration, we detected pulsed γ-rays from the Crab pulsar that were greater than 25 giga--electron volts, revealing a relatively high cutoff energy in the phase-averaged spectrum. This indicates that the emission occurs far out in the magnetosphere, hence excluding the polar-cap scenario as a possible explanation of our measurement. The high cutoff energy also challenges the slot-gap scenario.
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