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CRDC Mask Calibration
A pdf of the drawing of the crdc masks can be viewed here
NOTE-> The GValue "names" that we are using (currently) for mask calibrations are called
- CRDC1_Y_SLOPE
- CRDC1_Y_OFFSET
The slope and offset the CRDC_X values are always the same:
- CRDC#_X_SLOPE = 2.54
- CRDC#_X_OFFSET = -281.94
To get the initial slope Y values you must use the known values from the map pdf above and correlate them to the values you see in your map run file.
Notable points on the map pdf:
| Hole Number | Local Position [inches] | Centered Position [inches] | Centered Position [mm] |
|---|---|---|---|
| 29 | (12.3015,8.886) | (0,1.9685) | (0,50) |
| 61 | (12.3015,7.9018) | (0,0.9843) | (0,25) |
| 36 | (12.3015,6.9175) | (0,0) | a |
| 62 | (12.3015,5.9332) | (0,-0.9843) | (0,-25) |
| 46 | (12.3015,4.9490) | (0,-1.9685) | (0,-50) |
| 58 | (14.0742,8.0986) | (1.7727,1.1811) | (45,30) |
| 59 | (14.0742,7.7049) | (1.7727,0.7874) | (45,20) |
| 60 | (14.0742,7.3112) | (1.7727,0.3937) | (45,10) |
| 37 | (14.0742,6.9175) | (1.7727,0) | (45,0) |
| 55 | (9.3477,8.0986) | (-4.7265,1.1811) | (-120,30) |
| 56 | (9.3477,7.7049) | (-4.7265,0.7874) | (-120,20) |
| 57 | (9.3477,7.3112) | (-4.7265,0.3937) | (-120,10) |
| 35 | (9.3477,6.9175) | (-4.7265,0) | (-120,0) |
| 28 | (6.3960,8.8860) | (-7.6782,1.9685) | (-195,50) |
| 34 | (6.3960,6.9175) | (-7.6782,0) | (-195,0) |
| 45 | (6.3960,4.9490) | (-7.6782,-1.9685) | (-195,-50) |
| 30 | (18.2070,8.8860) | (4.1328,1.9685) | (105,50) |
| 41 | (18.2070,6.9175) | (4.1328,0) | (105,0) |
| 47 | (18.2070,4.9490) | (4.1328,-1.9685) | (105,-50) |
If you need more points for your fit you can determine the conversion between coordinate systems given the above table and us the map pdf to get the relevant values.
To obtain your slope and offset values simply get the raw values of all of the points you see from your mask calibration runs and compare them to the values in mm listed above (or obtained from the map pdf). Next perform a linear fit and take the slope of your linear fit and use if for your CRDC1_Y_SLOPE value in your .val file.
NOTE The CRDC1_Y_OFFSET is NOT!! taken from the linear fit described above. To get this value sort the run immediately after the mask run and look at the CRDCY value (through CRDC(0/1)->GetNonDispersiveY() in GRUTinizer) and take the negative of this value to be the offset from zero.
There are some marcro files available in the util directory that will make this more convenient if you wish. In the macro "CheckUnCalCRDCY.C" there are # functions. They are listed below, with a brief outline of how to use them and what they can do to make your life easier. *
The final part of this calibration is to determine if the calibration drifts throughout the experiment. If this happens it means that it is something changing with the detector (aka the drift time for the electrons has changed). The way to correct for this is with a SLOPE correction. This needs to be performed on a run by run basis, and the way this is achieved is simply by changing the CRDC#_Y_SLOPE for the run in your .val file.
The result is the final calibration is AWLAYS of the form: m*x+b
where m = CRDC#_Y_SLOPE and b = CRDC#_Y_OFFSET