g6c TOF calibration page(under construction!):

Standard TOF calibration procedure:

1.Status
2.Pedestals
3.Start Counter offset and Tagger offset
4.TDC calibration
5.Time-Walk correction
6.Left-Right alignment
7.Energy loss
8.Attenuation length
9.Effective velocity
10. Counter-to-counter offsets

We will briefly describe the calibration method that was used and show the quality of each step.

1. Status:
At the beginning of TOF calibration, we need to set all the counter status to be 0. In SC_CALIBRATIONS.map, one need to set the status for each counter in subsystem:status, items:left and right using the following conventions.

    "1" -no ADC;
    "2" -no TDC;
    "3"-no ADC, no TDC(PMT is dead);
    "5" - any other reconstruction problem;
2. Pedestals:
3. Start counter offset and Tagger offset:
    For start counter offset, the constant beign calibrated is stored in ST_CALIB.map.
By lookin at Pion vertex time - Start counter vertex time, one can determine st2tof (subsystem) value(item).
 

delta_T(subsystem) value(item).
 

4 and 5: TDC calibration and Time-walk correction calibration need special runs. Unfortunately, g6c did not take enough stastics for that purpose durign the running period. We used the constants from the later run(e1-6).

paddle2paddle:

we use pion vertex time - tof vertex time to calibrate the 288 TOF paddles. Pions are identified thru dedx-p (see plot).  TOF vertex time is constructed using ST vertex time to pick the right photon then propogate that photon to the target vertex.

check the following plots g6cPADDLE2PADDLE to see the quality of g6c paddle2paddle calibration. The tof paddles show a range of resolution from140 to 300ps.

The plot below shows an overall resolution of

TOF mass:

on this plot g6cTOFmasswe are fitting the TOF mass peaks at pion, kaon and proton region.

Fig 1 shows TOF mass of sec 1: where we see pion peak at 0.143GeV, kaon at 0.495GeV, Proton at 0.948GeV; The deutron signal appears around 1.9GeV.

   Fig 1-- Sec 1 TOF mass, G6c, run29808

To show the quality of the g6c TOF calibration, we can look at the beta:p plot:

Fig 2 beta:P for G6c data
 

Note: Fig 2 use the calibration low intensity data and processed with Kid program.
 

The above gif plots are also available in *eps format (mass1.eps and beta.eps).