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)

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)?