Hall A Beam Current Monitors (J.G. for Sasha, Roman and Vadym)

Pre-Long Shutdown Configuration EPICS CODA

Hall A BCM Calibration Procedure - I  Injector beam Goes through current monitor IBC0L02 Alternates in ~90 sec intervals between Faraday Cup#2 (IFY0L03) and Hall A  Hall A logs, Above two signals Upstream/Downstream BCMs (DVMs & Power Meter, if avail.) Unser V2Fs sent to CODA scalers See for details.

Hall A BCM Calibration Procedure - II  Calibration procedure sensitive to beam transmission through the machine  The Unser current transformer is logged but there is no procedure in place to compensate for the zero drift (either short or long term) -order of,  +/-2uA constant T,  +/- 5uA/°C  Sudden changes of up-to 2uA lasting hours or days (cause not known)  Above numbers are not determined by the electronics but by the magnetic material used to build the sensor head - best numbers obtained with Vitrovac 6025 (the heads we have).  The Unser is equipped with a current calibration source but it has not been used (to my knowledge).

POST-Long Shutdown Configuration (proposed)

 Keeps an already operational and well understood leg of the system so that experiments can take data while debugging & developing of the future replacement system goes on.  EPICS: replace IOCHA5 with network based soft-IOC to be able to perform calibration procedure as pre-long shutdown - mostly done, many systems in Hall A operate already this way  Build on Hall C BCM calibration procedure to use the Unser current calibration source and correct for the zero drift  Get the “Musson” 2 nd Generation (used in Qweak) or 3 rd Generation electronics (in fabrication) operational  There is already an “expert” EPICS control screen available for these units (used by Musson’s group to setup these units) but screens for non-experts need to be developed  Readout of these units into CODA - via DAC interface like the parity experiments (18-bits only) or access the internal digital bus for best resolution (24 bits)?