2,647 research outputs found
On the basic mechanism of Pixelized Photon Detectors
A Pixelized Photon Detector (PPD) is a generic name for the semiconductor
devices operated in the Geiger-mode, such as Silicon PhotoMultiplier and
Multi-Pixel Photon Counter, which has high photon counting capability. While
the internal mechanisms of the PPD have been intensively studied in recent
years, the existing models do not include the avalanche process. We have
simulated the multiplication and quenching of the avalanche process and have
succeeded in reproducing the output waveform of the PPD. Furthermore our model
predicts the existence of dead-time in the PPD which has never been numerically
predicted. For serching the dead-time, we also have developed waveform analysis
method using deconvolution which has the potential to distinguish neibouring
pulses precisely. In this paper, we discuss our improved model and waveform
analysis method.Comment: 4pages, 5figures, To appear in the proceedings of 5th International
Conference on New Developments in Photodetection (NDIP08), Aix-les-Bains,
France, 15-20 Jun 200
Numerical study of the photoelectron cloud in KEKB Low Energy Ring with a three-dimensional particle in cell method
A three-dimensional particle in cell simulation code has been developed to study the photoelectron cloud instabilities in KEKB LER. In this report, the program is described in detail. In particular, typical simulation results are presented for the photoelectron motion in various kinds of magnetic fields. The simulation shows that a solenoid is very effective in confining the photoelectrons to the vicinity of the vacuum chamber wall and in creating a region free of photoelectrons at the vacuum pipe center. The more uniform the solenoid field is, the more effectively does it suppress the electron-cloud buildup. Multipacting can occur both in a drift region and in a dipole magnet, and the heat load deposited on the chamber wall due to the lost electrons is important in these two cases. Electron trapping by the beam field as well as by various magnetic fields is an important phenomenon, especially inside quadrupole and sextupole magnets. Our numerical results qualitatively agree with the experimental studies
Studies on multiplication effect of noises of PPDs, and a proposal of a new structure to improve the performance
Pixelated Photon Detectors (PPDs) are the most promising semiconductor
photodetectors in recent years. One of the issues with the PPD is its high
noise rate. As well as random noise, PPD also exhibits so called after-pulsing
and optical crosstalk, and these limit the applicable range of its gain as well
as its size. By accurately measuring each of these causes of noises
independently, we quantitatively evaluated how the performance of the present
device is limited by multiplication effect of these noises. With this result
and the pulsing mechanism of PPD, we propose a new structure of PPD which could
have high gain with low noise.Comment: Submitted to Nuclear Instruments and Methods in Physics Research,
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