We report on the design and commissioning of two silica aerogel Cherenkov detectors with different refractive indices. In particular, very high performance in terms of the number of detected photoelectrons was achieved through an appropriate choice of PMT type and reflector, along with some design considerations. After four years of operation, the number of detected photoelectrons was found to be noticeably reduced in both detectors as a, result of contamination, yellowing, of the aerogel material. Along with the details of the set-up, we illustrate the characteristics of the detectors during different time periods and the probable causes of the contamination. In particular we show that the replacement of the contaminated aerogel mid parts of the reflecting material has almost; restored the initial performance of the detectors.
Performance of the two aerogel Cherenkov detectors of the JLab Hall A hadron spectrometer
PALMISANO, Francesco;VAN DER WERF, INEZ DOROTHE';
2009-01-01
Abstract
We report on the design and commissioning of two silica aerogel Cherenkov detectors with different refractive indices. In particular, very high performance in terms of the number of detected photoelectrons was achieved through an appropriate choice of PMT type and reflector, along with some design considerations. After four years of operation, the number of detected photoelectrons was found to be noticeably reduced in both detectors as a, result of contamination, yellowing, of the aerogel material. Along with the details of the set-up, we illustrate the characteristics of the detectors during different time periods and the probable causes of the contamination. In particular we show that the replacement of the contaminated aerogel mid parts of the reflecting material has almost; restored the initial performance of the detectors.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
