The pulsed light calibration system of the ZEUS calorimeter

doi:10.1016/0920-5632(93)90015-X

Nuclear Physics B - Proceedings Supplements

Volume 32, May 1993, Pages 106-113

https://doi.org/10.1016/0920-5632(93)90015-X Get rights and content

Abstract

The ZEUS calorimeter is a compensating calorimeter consisting of uranium and scintillator plates. Light is transported via light guides to photomultiplier tubes (PMTs). The design goal is an energy calibration good to within 1%. Stability is measured and PMT gains are set using the signal from uranium radioactivity. Another important component of the calibration is the pulsed light system, which distributes light from a central laser or from distributed LEDs to the photomultiplier tubes via optical fibers. The light pulse gives a similar PMT response as a signal generated by a particle in the calorimeter. This has allowed the monitoring of the following properties of the readout chain:

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• Number of photoelectrons/GeV/PMT. This enables us to differentiate between changes in the photomultiplier tubes and changes in the calorimeter (such as radiation damage).
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• Linearity of the PMT readout chain between 0 and 400 GeV.
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• Time delays from the PMTs and from the electronics are known to within 1 nsec. It is necessary to know these delays in order to precisely calculate the reconstructed charge and to eliminate background to e-p interactions from beam gas events.
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• Short-term monitoring of PMT gain. This has been used to measure PMT gain changes under varying magnetic fields to better than 1% and will be used to measure the PMT gain under varying HERA background conditions.

References (9)

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There are more references available in the full text version of this article.

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A gain monitoring system with a Nd:YAG laser for the photomultipliers of the HERMES experiment
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The Gain Monitoring System (GMS) provides real-time gain monitoring of the photomultipliers of the HERMES experiment, using a Nd:YAG laser with a wavelength of 532 nm as the light source. The system sends light pulses via an optical fiber network to the detectors equipped with photomultiplier tubes (PMTs), as well as to an array of reference detectors. Light pulses of different intensities are obtained by rotating a wheel carrying several attenuation plates in front of the light source. This permits the monitoring of the large dynamic range of ADC signals from the detectors, as well as the linearity of the PMT responses.
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^∗: Research funded by NSERC, BMFG, and DOE.

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The pulsed light calibration system of the ZEUS calorimeter

Abstract

DESY 91-083

DESY 91-027

Nucl. Inst. and Meth.