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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 G oes through current monitor IBC0L02 Alternates in ~90 sec intervals between Faraday Cup#2 (IFY0L03) and Hall A
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Hall ABeam 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 http://hallaweb.jlab.org/equipment/BCM/ 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 rms @ 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” 2nd Generation (used in Qweak) or 3rd 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)?