Revision as of 14:44, 16 June 2014

Detector Description

The Time-of-Flight (TOF) consists of ??? scintillator counters arranged in two planes. The upstream plane has counters running vertically(?) and the downstream plane has them running horizontally(?). Most have dimensions of ???x???x??? cm with exceptions noted below. The ??? in each plane consist of ??? counters with a PMT on each end, with ??? counters only read-out from one end (due to the beam hole in the center of the plane). Single-ended counters are of roughly half the length of the standard counters. In addition, the four double-ended counters nearest the beamline (two on each side) are of half-width (3 cm rather than 6 cm), to reduce counting rate.

Vertical plane counters have ends labeled "top" and "bottom" while horizontal plane counters have ends labeled "north" and "south". ??? The counters themselves are numbered from 1 to ??? going from top to bottom or north to south.???

The Time-of-Flight is located just upstream of the FCAL and downstream of the FDC. It is mounted on the forward carriage???.

All PMTs in the system are the same: Hamamatsu ?????. There are ??? PMTs altogether.

There are no devices providing environmental information (such as temperature) associated specifically with the TOF.

Shift Duties

Shift crews should be monitoring the following:

1. high-voltage status
2. statistical information from raw data ("monitoring histograms")

High-Voltage Status

In general, most important properties of individual HV channels will be monitored automatically by the EPICS alarm system and shift crews need to respond to alarms as they arise. To facilitate this, each shift a check should be made that the TOF HV??? is up and running.

The conditions that may cause EPICS alarms are:

• tripped voltage
• read-back voltage out-of-range
• supply current out-of-range
• EPICS communication lost

Shift crews should check the guidance for the alarms as provided by the alarm handler.

Statistial Information

Each run produces a set of monitoring histograms that should be compared to nominal histograms and scanned for anomalies. The histograms include:

• occupancy, channel-by-channel
• end-to-end coincidence rates (where appropriate)
• geometrical distribution of plane-to-plane matches
• timing distributions

Trigger Monitoring

The TOF calibration trigger should be running at about ??? percent of the total triggers during normal running. If this is not the case contact the trigger or TOF expert.

Detector Expert On Call

The individuals responsible for the operation of the TOF are shown in the following table.