Detector

The MiniBooNE tank is 12 m diameter sphere, filled with approximately 800 tons of mineral oil, CH2, which has a density of 0.845 ± 0.001 g/cm3. 1280 PMTs provide about 10% coverage of the inner tank region, and 240 PMTs cover the outer, optically isolated "veto" region in the last 1.3 m in the tank. Most of the tubes were recovered from LSND, and are 'old' tubes, some additional ones were bought for MiniBooNE, and are 'new'; differences in the new vs the old tube function are accounted for in the Monte Carlo. See also Fermilab's Visual Media Services try 'MiniBooNE Tank' for the caption		click to enlarge
Time and charge information is recorded for each PMT hit occurring within a 19µs time window around each beam spill. "Subevents" are formed by finding time clusters of at least 10 PMT hits. image: Subevent time distributions (no cuts) image: Subevent time distributions (Tank hits > 200) image: Subevent time distributions (Tank hits > 200 & Veto hits < 6) Cosmic ray induced events are reduced by over three orders with respect to beam induced events by simply requiring that there be >200 PMT hits in the inner tank region and <6 PMT hits in the veto region.