BCM Calibration

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(copied from GMP)

BCM Calibrations [2 hours]

Procedure:

1. The absolute calibration of the bcm is done with the Faraday in the accelerator (OLO2) cup or the unser. In case the Fraday cup is used, you need to request it to the MCC. In this experiment we used the unser as the absolute calibration measurement. The unser calibration is done using the wire, in no production beam time.
   1. Use the wire to calibrate the unser. To access to the wire current supply, in epics look for the Hall A Menu -> BCM -> Unser monitor.
   2. Send to the wire different currents 0,5,0,20,0,40,0,60,0,80,0,100,0 (uA). Each current should be send for at least 90 seconds. Record the data from the DAQ system.
   3. The unser is a very noisy device. Therefore, the 0 (uA) are sent to subtract the local background for each current.
   4. In a graph of the current vs the frequency recorded by the DAQ, and calculate the gain of the linear fit. The offset of the graph should be nearly zero, since the local background was subtracted.
2. Also start a HRS run to record the scalers during the calibration procedure, if necessary use the clock to take reasonably high data rate (above about 50 Hz at least)
3. It is useful to have someone over in MCC to help coordinate the calibration with them.
4. Take data on carbon target with I = 0, 3, 0, 5, 0, 7, 0, 10, 0, 15, 0, 20, 0, 25, 0, 30, 0, 40, 0, 50, 0, 60, 0, 70, 0, 80, 0 μA (or as high a current as available). Each beam period (with or without current) should last 90 s. If you get a trip during a beam up period, take 90s of beam off and restart that beam up period.

SRC data of calibration:

The unser data was take before the commissioning period:

Run 662 (Left Arm) and 90436 on December 03/2017.

The currents used where:

0, 100, 0, 20, 0, 50, 0,7 0, 0, 30, 0, 90, 0, 90, 0, 20, 0, 60, 0, 80, 0, 40, 0, 100, 0, 20, 0, 50, 0, 70, 0, 30, 0, 90, 0, 20, 0, 60, 0, 80, 0, 40, 0, 10, 0, 10, 0

December 14/2017 data of calibration

In the bcm calibration, the beam needs to be as stable as possible.

The data was taken in the owl shift of December 14/2017.

Beam Current (uA)	LHRS CODA run	RHRS CODA run	Comments
40	815	90605
30	815	90605
20	815	90605
10	815	90605
5	815	90605

General comments: the different currents were taken for 90 minutes or as long as the beam didn't trip.

Each current was taken two times.