E158 Run III Polarimetry
Checklist
**Many items have
changed since Run II; follow this checklist carefully.
**Print out checklist and check off items as you go along.
**When completed, file checklist and analysis printout into
Polarimeter Binder.
SETUP:
·
Check with CryoTech and MCC 5 minutes in advance of starting procedure
to verify that this is a good time to do the measurement.
Anticipated time for setup, data-taking and recovery is 45 minutes. The beam
needs to be at 10Hz for 45 GeV. Polarimetry
runs are performed with full current.
·
Call MCC to inform
them that you will suppress beam for setup.
o Request MCC to setup for 10Hz beam.
·
Check with Run Coordinator whether or not the
half-wave plate should be toggled.
·
Verify that wire array
is in the OUT position. (if not, take it out)
·
Notify the cryo-tech, and put the LH2 target into the OUT position.
o
Consult the E158 Target OPS. Manual and go to the green-tabbed procedure for moving the target out of
the beam.
o
Make sure to put the heater mode to “MANUAL” in the Target Heater Control window of the
target control (labview) program after raising the
target out of the beam.
·
Move 3CM8 collimator
and tungsten blocks to their OUT positions.
o
For the tungsten
blocks, the “OUT” position is 50.0 cm.
·
Verify that 3QC1A is
OUT (will
remain out at all times).
·
Make sure the screens 3PR2,
3PR3, 3PR4 are OUT.
·
Put IN the 20 um polarimetry
target foil.
·
Turn on the 3T0 Helmholz coils.
o
Follow operating
procedure for 3T0 power supply (posted on Rack 54) to turn on supply and set
operating current,
o
WARNING ! You must follow this procedure carefully.
o
The supply is unipolar. Any request for
polarity reversal must be cleared by the run coordinator (M. Woods or MO) and
performed by authorized persons (T. Tuck or MO).
·
Place the polarimetry detector (scanner) at Y = 21.0 cm.
·
Check that polarimetry detector HV is 700 Volts. If not, set it to this value
·
Quadrupoles are to be left
at their current production settings.
o
Be sure to clearly
label the quad values in the run sheet.
·
Do FBANAL setup for
the (new) halfwave plate configuration. (only if required)
o
set CP, PS voltages
appropriately
l/2 State |
|||||
CP |
PS |
|
|||
Right |
Left |
Right |
Left |
|
|
IN |
2398 |
-2725 |
-313 |
-316 |
|
OUT |
2302 |
-2821 |
-190 |
-193 |
|
o
reset and clear data
for feedbacks (Intensity and Position)
·
Call MCC to check that
they are ready to give 10Hz beam and that the wave plate was set correctly.
o
Verify wave plate
setting with FBANAL Feedback Configuration Display.
·
If MCC is ready, unsuppress beam.
MEASUREMENT:
RECOVERY:
Data
Analysis:
On a noric
CPU, from any account with the MayDay setup open two windows, one for running the analyzer, another
for running PAW. Let us assume we have a polarimetry
(foil) run NNN1 and a background (no target) run NNN2 to analyze.
In the 1-st window:
noric04$ cdPol
noric04$ run.pl NNN1
** In case of problems please contact Yury . **
In the 2-nd
window:
noric04$ cdPol
noric04$ cd paw_2003
noric04$ paw
PAW> exec run run=NNN1
PAW> exec
run run=NNN2
PAW> exec checku run=NNN2 helmh=84.0 hv=700 (analyze the bkgd. run)
Before analyzing the foil data, wait for the background to
finish and look at the output. Look for a line that reads something like: “signal/tor: 29.78 +/- 0.02” This is the background subtraction that you will put into the
actual foil analysis:
PAW> exec checku run=NNN1 helmh=84.0 hv=700 bgnt=29.78
The last command will analyze the
run, subtract the background and print useful information. In case the signal
saturates or is close to saturation it would suggest the HV to use. These are a good
example of the output plots and a bad
example (saturation).
Documentation:
Make sure to document carefully in the polarimetry
run sheets the HV used, the coil current (84A at 22.5V), the rep. rate of the beam (10Hz, not the
60Hz DAQ rate), and the quadrupole settings (typically nominal).
TIPS for the PAW analysis:
Storing the picture in a local file paw.ps
and printing it:
PAW> opla
PAW> exec check_1 run=NNN1 hv=700 helmh=84.
PAW> clops
PAW> prpc1
About 20 runs can be attached at the same time. One can
also check the logical units by:
PAW> ld // and use PAW commands to read the ntuple and fill histograms using the appropriate unit.
Detector Y(R)-scan:
PAW> exec yscan
run=NNN1
Target position scan:
PAW> exec trg_scan
run=NNN1
In case of
problems please contact Eu
Note: The
analysis procedure above is crude, with a purpose to make sure the data are
good. The next step would be the background subtraction procedure. It will be
added later.
Last Updated:
Robert Michaels --
e-mail: rom@jlab.org
Eugene
Chudakov -- e-mail: gen@jlab.org