Difference between revisions of "BCM Calibration"
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<ol> | <ol> | ||
| − | <li> The absolute calibration of the bcm is done with the Faraday 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. | + | <li> 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. |
| + | <ol> | ||
| + | <li> 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. | ||
| + | <li> 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. | ||
| + | <li> The unser is a very noisy device. Therefore, the 0 (uA) are sent to subtract the local background for each current. | ||
| + | <li> 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. | ||
| + | </ol> | ||
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| + | |||
| − | |||
<li> Before beginning the procedure, make sure the Hall A BCM logger and the HRS DAQ are started, which will record the signals from all relevant BCM used during the calibration. [[http://hallaweb.jlab.org/equipment/BCM/BCM_logger.html Here ]] is how to start the logger, choose the BCM logger script (solution 2). | <li> Before beginning the procedure, make sure the Hall A BCM logger and the HRS DAQ are started, which will record the signals from all relevant BCM used during the calibration. [[http://hallaweb.jlab.org/equipment/BCM/BCM_logger.html Here ]] is how to start the logger, choose the BCM logger script (solution 2). | ||
<li> 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) | <li> 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) | ||
Revision as of 06:50, 14 December 2017
Back to Installation and Commissioning
(copied from GMP)
BCM Calibrations [2 hours]
Procedure:
- 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.
- 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.
- 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.
- The unser is a very noisy device. Therefore, the 0 (uA) are sent to subtract the local background for each current.
- 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.
- Before beginning the procedure, make sure the Hall A BCM logger and the HRS DAQ are started, which will record the signals from all relevant BCM used during the calibration. [Here ] is how to start the logger, choose the BCM logger script (solution 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)
- It is useful to have someone over in MCC to help coordinate the calibration with them.
- 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.
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 as long as the beam didn't trip.