Status report TOF/T0 data in PR03

	Frank L. H. Wolfs
	University of Rochester
	January 17, 2003

Outline

	T0 Calibrations
	TOF Calibrations and Results
	Issues to be addressed in the next week or two.
	Note: all data shown here are data obtained in run 10511.  This is a run with magnetic field on.

Software status

	Rough energy calibration for T0 in the DB.  TOF is not calibrated yet and PR01 pulse-height calibration is used to look at the current data.
	First rough time calibration for T0s will be implemented this weekend,
	T0 and TOF data are now included in the trigger trees (committed to CVS at noon on 1/16).  The sum energy and multiplicities are roughly correct.
	Automatic calibration procedures are not automatic and in fact do not run reliably.

T0 calibrations

	A first order energy calibration of the T0s is in the DB.
	We need to monitor the gains in the PMT, although they appear to be very stable (despite the fact that we keep turning the counters on and off).
	Firs order time calibrations need to be made, in order to ensure that the vertex information in the trigger trees makes sense.

T0 correlations

	The multiplicity in the T0s is correlated with the multiplicities in the paddles.
	The correlation is similar for the N and the P side, except of the fact that the multiplicities are lower on the P side (for both paddles and T0s) compared to the N side.

T0 correlations

	The sum energy in the T0s is correlated with the sum energy in the paddles.
	As expected, the sum energies are in general lower on the P side compared to the N side.

TOF Multiplicities

	The figures show the TOF multiplicities for wall TB and wall TC.  The following requirements must be satisfied:
		A good pulse height in both top and bottom PMTs.
		A prompt time signals in both top and bottom PMTs.
	Observations are similar to those made by the SpecTrig group: the multiplicities for collision events (red) are much lower than the multiplicities for beam-gas events (blue).

TOF Energy

	Using the last calibration parameters of PR01, we gain-matched the PMTs and reconstructed the TOF energy based on the measured pulse heights.
	The calibration is in terms of MIPS, but the calibration parameters depend on the average angle of incidence, which is a function of position/orientation of the walls and the field.

TOF Energy

	Comparing collision events with beam-gas events we observed MIP peaks for both events.
	The main difference between beam-gas and collision events is the signal-to-background ratio.
	The background in wall TC is higher than the background in wall TB.

TOF Sum Energy

Conclusions and concerns

	The data for both TOF and T0 look good.  The critical change that was made in the RHIC operation that changed the TOF from a BLM to a good detector was the reduction in background.
	It will need 1 - 2 weeks before the TOF and T0 calibration procedures are finalized, and it would be bad if DV was frozen before then.  Note that none of the Au - Au calibration procedures work at the moment due to changes in triggering and changes in multiplicities.
	Can we keep time calibrator events in the PhoHit files?  We need to get more experience with how to correct the data collected on the fly.