From gartung@neutrino.physics.ucsb.edu Mon Oct 20 08:24:52 2003
Date: Tue, 26 Aug 2003 16:21:21 -0700 (PDT)
From: Patrick Gartung <gartung@neutrino.physics.ucsb.edu>
To: elis@fnal.gov, leonard@fnal.gov, tten1 <tten1@uic.edu>
Cc: Anthony Allen Affolder <affolder@neutrino.physics.ucsb.edu>
Subject: Calibration of electrometers

Hi,

Here is what you need to do to readout the bias current with the
electrometers.

1. Connect the output of the CAEN channel to the input of the
electrometer, the output of the electrometer to the input of the HV
crowbar and the output of the HV crowbar to the PAACB HV connector.

2. Connect the front panel electrometer output to ADC input board.

3. In ~/Lt/Config/lt.xml each bench position should have a HV connection
description like this:


    <BiasHvConnection  device= "1000" simulation= "n"   >
		<HvCaenA434 gain="1" >
		<CaenNetChannel cratenr="10000" channel="0"
		       			shmname= "ControlePrincipal" />
      		</HvCaenA434>
    </BiasHvConnection>

    <BiasCurrentConnection device= "1000"  simulation="n" >
      <BiasCurrentAdcChannel>
	<ElectroMeter
	  ElectroMeterType = "cern_msgc"
	  ElectroMeterRange = "100uA"
	  ElectroMeterChannel= "0"
	  ElectroMeterOutputRange= "10"
	  />
	<CalValues
	  gain="0.96125"
	  caladcvalue="770"
	  calcurrent = "0"
	  />
	<AdcChannel
	  boardnr="0"
	  channel="16"
	  />
	</BiasCurrentAdcChannel>
    </BiasCurrentConnection>


Check that each BiasHVConnection CAENNetChannel has the correct channel.
Channels on the HV crate are number from 0 starting with the leftmost HV
module, top connector and proceding down and then right.

Check that the AdcChannel is set to whatever input you plugged into (the
lemo connectors are numbered with the ADC channel).

The device numbers should be unique for each bench position.


The gain should be the same if you use the following line in
~/Daq_Cms_Like/Acquisition/bin/daq.xml

<Adc device="0" frequency="1000" gain="UP_10_00V"/>


The caladcvalue is determined by running
~/Lt/ClientTools/TestLtCurrent with the HV set to 0 and the electrometer
turned on. To compile TestLtCurrent:

cd ~/Lt/ClientTools/test/
make TestLtCurrent
cd bin
TestLtCurrent 1000

The argument of TestLtCurrent is the device number assigned above. The
output varies a few ADC counts so just take the lowest of 10 readings.


The highest reading using these settings is aroun 160 microAmps. The HV
crate has a limit of 1 microamp set by the software. If this current is
exceeded the channel trips. If you need to measure a really noisy module
you can change the current limit in the software. Just edit
~/Lt/ModuleHv.cc and change line 29:

 thehvch->setHvCurrentLimit(1);

to

 thehvch->setHvCurrentLimit(1000);

The argument of the function if the current limit in microAmps.

Regards,
Patrick