CBHV

Scripts and tools for the Crystal Ball High Voltage

Calibration of the CBHV values using a source

The procedure for how to perform a calibration of the CBHV values using an AmBe source is documented on the a2wiki: https://a2wiki.kph.uni-mainz.de/experiment/detectors/cb/source_calibration

Most of the code needed for this procedure is provided by ant (https://github.com/A2-Collaboration/ant). Stored in this repository are all the produced lists of CBHV values, dated by year and month, as well as a macro which can be used in the end of the procedure.

Calibration of CBHV cards

Everytime a PMT get's exchanged or even a splitter card is broken and exchanged, a calibration of the correction values has to be done. There are some crucial steps:

• Stop the CBHV EPICS IOC on slowcontrol
• Set correction loop and correction values to 0 using the script cbhv_control.py with the option -r or --reset
• Measure the new correction values using the same script cbhv_control.py with the option -c or --calibrate; the measurement will take around 6-8h to finish
• analyse data with root and cbhv_calibrate_boxes.C
• optional: convert all ps to pdf and add them together with convert_add_ps2pdf.sh
• finally set the correction values with cbhv_control.py, providing the input file eg. .\cbhv_control.py -i HV_gains_offsets.txt This will also activate the correction loop again

Additional options

• You can specify only certain boxes by using -b or --boxes and providing a list of boxes, e.g. -b 1 2 4 12
• For the calibration you might want to change the stepping or the voltage range, -s 20 --range 1300 1500
• For a full list of options run cbhv_control.py with -h or --help

Tips

By default, running the ROOT macro creates a PDF with the histograms for the different channels. For every card a PDF is created. If you want to merge them to one file, you may want to use pdftk:

pdftk HV_gains_offsets*.pdf cat output HV_gains_all_cards.pdf