Analysis of High Rate Photomultiplier Tubes in KamLAND
Abstract
The Kamioka Liquid-scintillator Anti-Neutrino Detector, KamLAND, measures the barν flux from nearby nuclear reactors in Japan and Korea. KamLAND's outer detector is a water filled Cherenkov detector consisting of 225 20'' photomultiplier tubes refurbished from the Kamiokande experiment. The outer detector provides an offline veto of muon induced background events in the primary, inner, detector. High rate tubes, especially when clustered, interfere with the data acquisition system and very often prove difficult to isolate causing increased downtime. Data from the outer detector was analyzed to characterize the high rate behavior. The analysis included a search for correlations between neighboring high rate tubes. Specifically, the time structure of tube pulses was examined to determine if the tubes could be ``flashing'' or physically producing light being observed by neighboring tubes. Upper limits have been established on timing correlations between pulses from clustered high rate tubes. Analysis using other tube characteristics with higher complexity such as pulse shape is ongoing. Results will be presented which classify and describe the failure modes of the tubes in the outer detector.
- Publication:
-
APS Division of Nuclear Physics Meeting Abstracts
- Pub Date:
- October 2003
- Bibcode:
- 2003APS..DNP.8P024F