The QCluster cut is not intended primarily as a data cleaning cut, but rather is useful as an ID of particular types of events, such as Wet-End Breakdown, flashers, and sharkfins. The basic idea behind the QCluster cut is to look for events which have a cluster of hit channels on a paddlecard (the same as in the Cluster cut) and which also have channels which fail the charge cut within that cluster. For flasher and sharkfin events, the number of railed charges in a cluster tends to be just one, for Wet-End Breakdown events it can be three or more. The QCluster cut is basically a direct combination of the SNOMAN Cluster cut and the SNOMAN charge cut. However, unlike the Cluster cut, the QCluster cut finds all possible clusters in an event, and loops over these, looking for any which have the requisite multiple railed charges in them.
The cut is coded as a SNOMAN hard-wired cut, `flt_qcluster_cut.for.' The parameter for controlling the cut are found in filter.dat:
*DO FLTH 13 -i(30I 2F 2I 12F -I) #. FLTH: QCluster #. 19750101 0 20380517 03331900 6*0 #. Standard Database Header 19750101 0 20380517 03331900 16*0 #. 6. #. Max number of hits on a card #. #. 3 #. i charge cut mode 1=raw ADC, 2=pedestal subtracted, #. 3=pedestal subtracted for calibrated channels, #. raw ADC for other (this is the standard) #. For modes 2,3 you use pedestal subtracted charge with CAL 3 #. i threshold number of channels with bad charge to reject event #. 250. #. r QIHS Lowest acceptable charge : For mode 1,3 4000. #. r QIHS Highest acceptable charge : For all modes 250. #. r QIHL Lowest acceptable charge : For mode 1,3 4000. #. r QIHL Highest acceptable charge : For all modes 300. #. r QILX Lowest acceptable charge : For mode 1,3 4000. #. r QILX Highest acceptable charge : For all modes #. -100. #. r QHS Lowest acceptable charge : For mode 2,3 -100. #. r QHL Lowest acceptable charge : For mode 2,3 -100. #. r QLX Lowest acceptable charge : For mode 2,3 #. 0 #. i Number of crates to ignore GET THIS RIGHT! #. Format integer crate e.g. 0 for crate 0 #. Start of bad crate list #. End of bad crate list #. 0 #. i Number of cards to ignore GET THIS RIGHT! #. Format integer crate*100+card e.g. 0005 for crate 0 card 5 #. Start of bad card list #. End of bad card list #. 0 #. i Number of channels to ignore GET THIS RIGHT! #. Format integer crate*10000+card*100+channel #. e.g. 000512 for crate 0 card 5 chan 12 #. Start of bad channel list #. End of bad channel list -99 #. i End of bank marker
These parameters are identical to those used in both the Cluster cut and the Charge cut, with the exception that the `max number of hits in a crate' is missing, and the fact that the `threshold number of channels with bad charge' now refers to the number of bad charges in a channel hit cluster.
To use the cut, one can put a call flt($qcluster_cut) in the programmable event loop. The cut returns `true' if the event is a good event (that is, does NOT have a charged cluster).