نتایج جستجو برای: cherenkov counter
تعداد نتایج: 42887 فیلتر نتایج به سال:
For several years the only experiments sensitive to astrophysical gamma rays with energies beyond the reach of EGRET but below that of the Cherenkov imaging telescopes have been the ”solar tower” detectors. They use > 2000 m mirror areas to sample the Cherenkov wavefront generated by < 100 GeV gamma rays, obtaining Crab sensitivities of more than 6σ in one ON-source hour. I will review the hist...
We present data that illustrate some advantages of Cherenkov counting for the radioassay of 90Y in the dry state and provide recommendations concerning sample counting geometry. Slightly higher detection efficiencies and figures-of-merit were obtained when counting 90Y in the dry state in polyethylene plastic counting vials compared to the counting of 90Y in 20 ml of water in borosilicate glass...
It is well-known that a charged particle moving with constant velocity in vacuum does not radiate. In a medium the situation can be different. If the so called Cherenkov condition is satisfied, i.e. the particle velocity exceeds the phase speed in the medium, the particle will radiate. We show that a charge moving with a constant velocity in a gas of photons emits Cherenkov radiation, even in t...
Very energetic cosmic rays entering the atmosphere of Earth will create a plasma cloud moving with almost the speed of light. The magnetic field of Earth induces an electric current in this cloud which is responsible for the emission of coherent electromagnetic radiation. We propose to search for a new effect: Because of the index of refraction of air, this radiation is collimated in a Cherenko...
The DIRC, a new type of Cherenkov imaging device, has been selected as the primary particle identification system for the BABAR detector at the asymmetric B-factory, PEP-II. It is based on total internal reflection and uses long, rectangular barsmade from synthetic fused silica as Cherenkov radiators and light guides. In this paper, the principles of the DIRC ring imaging Cherenkov technique ar...
Atmospheric density profiles as well as several light absorption and scattering processes depend on geographic position and are generally time-variable. Their impact on the atmospheric Cherenkov technique in general (imaging or non-imaging) is investigated. Different density profiles lead to differences in Cherenkov light density of up to 60%. Seasonal variations at mid-latitude sites are of th...
The Cherenkov light flashes produced by Extensive Air Showers are very short in time. A high bandwidth and fast digitizing readout, therefore, can minimize the influence of the background from the light of the night sky, and improve the performance in Cherenkov telescopes. The time structure of the Cherenkov image can further be used in single-dish Cherenkov telescopes as an additional paramete...
Using aerogel as radiator and multianode PMTs for photon detection, a proximity focusing Cherenkov ring imaging detector has been constructed and tested in the KEK π2 beam. The aim is to experimentally study the basic parameters such as resolution of the single photon Cherenkov angle and number of detected photons per ring. The resolution obtained is well approximated by estimates of contributi...
Imaging air Cherenkov telescopes (IACTs) like MAGIC detect the Cherenkov light from extensive air showers (EAS) initiated by very high energy (VHE) γ-rays impinging on the Earth’s atmosphere. Due to the overwhelming background from hadron induced EAS, the discrimination of the rare γ-like events is vital. The influence of the geomagnetic field (GF) on the development of EAS can further complica...
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