Difference between revisions of "Compton"

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The Compton polarimeter can be used to non-invasively monitor the beam polarization. It has three major components: an optics table with a laser that can lock to a Fabry-Perot cavity; an electron detector to count scattered electrons; and a photon detector to count scattered photons. At present, the electron detector is in commissioning, so only the photon detector is fully functional.
+
== The Hall A Compton ==
  
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There is additional documentation at [http://hallaweb.jlab.org/compton Hall A compton webpage]
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The Compton polarimeter is used to (non-invasively) monitor polarization of the incoming electron beam.  
 +
It has three major components: an optics table with a laser that can lock to a Fabry-Perot cavity, an electron detector, and a photon detector to count scattered electrons and photons, respectively.
  
 +
Last edit: [[User:Lthorne|LThorne]] 02:08, 24 February 2016 (UTC)
  
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=Green Fabry-Perot Cavity=
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<!-- Comments -->
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<!-- Please replace text after "Last edit: " with "~~~~" when editing relevant section. -->
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<!-- Last edit on {{REVISIONYEAR}} {{REVISIONMONTH}} {{REVISIONDAY2}}, by {{REVISIONUSER}} -->
  
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=Standard Compton=
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== Shift Workers' Operation Guide ==
  
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Monitoring the beam polarization using the Compton polarimeter requires two steps:
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Start a Compton run every two hours.
  
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*Take Compton data. These can be long runs, but since you can only check the polarization after a run has ended, it is best to start a new run every hour or two. When you end a run, click "Submit" to dismiss the gray pop-up window.  
+
The Compton DAQ is located in the back room in the Counting House. All commands are done from compton@compton.  
  
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* After a Compton run has analyzed (this takes about 10% the length of the run), check the logbook [1] for the Compton asymmetry.
+
If CODA is not already running:
  
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If runcontrol shows that it can't communicate with a ROC or if the data won't analyze, stop the current run and type "coda reboot" into a compton@compton terminal window to reboot the ROCs and CODA. If the problem is with ER1, you will need to type
+
: Kill CODA first, then start it up again:
  
−
    coda_er -n ER1
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    $ kcoda
 +
    $ startcoda
  
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into a separate window.
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: A few new Terminal windows and a GUI pop up.
 +
:: [[Image:LT CODAgui.png|800px]]
 +
: Let "top" refer to the bar with named menu options near the top of the GUI (ex: Platform, Sessions, etc). Let "bottom" refer to the bar below "top" that contains a line of buttons (hover over them to reveal their labels; starting with "Configuration" on the left).
 +
:# In top, select: Platform > Connect
 +
:# In bottom, click on "Configuration" button.
 +
:#* If configuration listed in the "Run Parameters" box is not '''FADC_prod''': in top, select Configurations > Cool and change it to '''FADC_Prod'''.
 +
:# In bottom, click on "Download" button
 +
:# In bottom, click on "Prestart" button
 +
:# When ready to start run, click "Start" button. Typical run duration: 2 hours. Type in any Start Of Run comments in the box. Click "OK" (even if you left comments blank!).
 +
:# When ready to stop run, click "End" button. Type in any End Of Run comments in the box. Click "OK" (even if you left comments blank!).
  
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See below for more details.
+
== Information for Compton Experts ==
 +
=== Troubleshooting ===
 +
# HV on/off? -> [[Compton#High Voltage Controls]]
 +
# Rebooting components: [[Compton Reboot]]
 +
# [Experts only]: Correct parameters for run in ''integratingDAQ.flags'' and ''compton.params''
  
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==Presentation==
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=== Collimator Systems ===
  
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The Compton is run from the compton machine, which is the leftmost active monitor in the back room of the Hall A counting room. The login name is compton and the password is the same as the one for the adaq account.
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[[File:Jaws_positions.PNG|thumb|300px|What the jaws look like when placed at their lowest position, as seen on comptcam2. To view this camera follow [http://comptcam2.jlab.org this link] and login with compton credentials.]]
 +
* Primary Lead Collimator
 +
** Presently left fully open at 20 mm diameter.
 +
** This is a 10 cm long collimator with inserts which can reduce aperture down to 10 mm or 5 mm in diameter.
 +
* Synchrotron Shields
 +
** For PREX-II a single 0.25 mm lead foil (painted) is taped to the front of the photon detector.
 +
* Compton Jaws
 +
** Remote access for experts can be found at [http://compjaws.jlab.org]
 +
** Note, for the duration of the PREX-II running period, the Compton Tungsten Collimator System ("Compton Jaws") will not be used. It should be left it is's parked position of:
 +
    aperture =  1.5 mm
 +
    y center = -46.0 mm
  
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To begin a new CODA instance, type
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=== Detector Positioning System ===
  
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    coda start
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* Centering Beam & Photon Detector
 +
** Refer to section [[Compton Photon Detector Centering Procedure]] for more info.
 +
* For controls, troubleshooting: [[Compton Photon Detector]]
 +
* Home position of photon detector table:
 +
{| class="wikitable"
 +
! Date
 +
! X [mm]
 +
! Y [mm]
 +
! Comment
 +
|-
 +
| 2019-06-17
 +
| 70
 +
| 33.5
 +
| Visually Centered
 +
<!--
 +
|-
 +
| 2019-XX-XX
 +
| XX
 +
| XX
 +
| XX
 +
-->
 +
|}
  
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To recover from a CODA crash, type
+
=== Cameras ===
 +
* [http://comptcam1.jlab.org ComptCam1]: Detector Table
 +
* [http://comptcam2.jlab.org ComptCam2]: Tungsten Jaws
  
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    coda reboot
+
=== High Voltage Controls ===
 +
* [[HV Control GUI]]
  
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To open a strip chart, type
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=== LED System (Linearity Measurement System) ===
 +
* Will add info on MiniMegan soon
  
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    StripTool HappexIIICompton.stp
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'''Taking an LED run:'''
  
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==Operation==
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# Find parameter file GUI:
 +
    $ cd /home/compton/franklin/
 +
    $ ComptonConfig
 +
# Click "Pulser On, Pulser Trigger" on parameter file. Click "Apply", then "Done" to close GUI.
 +
# Go to CODA. Start a new run to apply the settings. (This does not need to be a long run. You may end it immediately.)
 +
# Start your LED run.
 +
# ''When you go back to normal Compton runs: don't forget to turn the pulser off and do a short run to update the parameter file settings!''
  
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To start a run, click the "Start" button in the runcontrol window. After a time, you should see the event count start to go up and the message "Transition Go Succeeded" at the bottom of the screen.
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=== Laser System ===
  
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To setup the compton trigger parameters use the spyconf program :
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[[Real time o-scope signals]]
  
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  spyconf
+
[[Cavity lock camera]]
  
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[[Image:Spyconf.jpg]]
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[[Make sure laser flipping is on]]
  
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One can select the different data taking modes in General Daq Setup.
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[[Turning off the laser]]
  
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On the right panel one can setup the photon detector parameters. We are using only the central crystal only.
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[[IOC reboot]]
  
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On the bottom middle pannel, one can setup the electron detectors parameters.
+
[[Accessing the laser hutch in the hall]]
  
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number of planes needed to generate a trigger
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[[Laser and Locking troubleshooting]]
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coincidence time windows between planes
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number of adjacent strips ored to be looked in the next plane for the trigger
+
  
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When it is time to end a run, click the "End Run" button in the runcontrol window. A gray screen should pop up, giving you the opportunity to enter a message (say, if the beam was very trippy). Make sure you dismiss the window by clicking "Submit" -- not "Exit"! Hitting "Submit" sends the run to the analyzer, which is very important.
+
== Software & Data Analysis ==
  
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You may additionally get a pop-up window saying "End run failed!" on the runcontrol window. This is okay. Dismiss this popup window and click the "Reset" button on runcontrol. (Yes, despite the dire warning, you really do want to do this.) You should then be able to start the next run.
+
Relevant files, scripts, etc.
  
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While running, you can monitor the beam current, photon rates, cavity status, etc using a strip chart.  Here's what it might look like:
+
'''Run Compton analysis:'''
  
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[[Image:Transversity_striptool.jpg|800px]]
+
In compton@compton:  
  
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* Purple line: Beam current (uA). In the figure you can see that it has tripped a few times.
+
    $ cd /home/compton/online/CompMon
−
* Yellow line: Vertical beam position. This should remain roughly constant. A beam trip sends it to the top of the chart (position 0).
+
−
* Red line: Cavity power. This should be a square wave: the cavity is locked in the right polarization state, then turns off, then locks in the left polarization state, then turns off, then repeats. The powers for the right and left states appear different but are actually the same. The power should stay comfortably above 400 W. (Cavity will not lock during extended beam trips.)
+
−
* Blue line: Scattered photon rates in the detector. As in the figure, these should track the cavity on/off states; if you can tell from the blue line alone whether the cavity is on or off, then you are probably getting good Compton data.
+
−
**If this is not the case, this may be due to a bad tune resulting from very low current, or the Compton chicane is off. If one of these is not the cause, contact a Compton expert.
+
−
**If your blue line is zero or not displaying, there are three possible causes:
+
−
***Beam trip
+
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***HV trip. Check the Beamline HV card 11. Channel 1 should be set to -1800 V for the GSO detector.  If the HV is tripping over and over again, call a Compton expert.
+
−
***DAQ is not running. Start a CODA run and the blue line should come back. If CODA is already running, it may be in a strange state;
+
−
end the run and type "coda reboot" into a terminal to restart the ROCs and CODA, then start a new run.
+
  
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==Checking a Run==
+
Run analysis software:  
−
Compton analysis results are written to the Compton logbook, which can be accessed onsite at [http://hallaweb.jlab.org/compton/Logbook/]
+
  
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Find the run number (newest runs are at the top) and click the '''html''' link. (The pdf link does not work.) This will open a new window with the analysis results.
+
    $ ./compmon <run number, no brackets>
  
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The full results will not display right away (because the analyzer does not finish immediately). It takes the analyzer about 10% of the runtime to complete. So an hourlong run will be analyzed after about 6 minutes.
+
Open ROOT:
  
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The most important graph is about a third of the way down the page. You can find it quickly by searching the page for "Counting Rates". It's the graph titled '''Asym in ADC bins''':
+
    $ root -l /data/cmuwork/rootfiles/Fall2016/compmon_<run number, no brackets>.root
  
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[[Image:Compton_asym_graph.jpg]]
+
Run desired C script located in CompMon directory.
  
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Here are the important things to look for:
 
  
−
* The green line (cavity off) should be consistent with zero. This shows that there is no asymmetry in the background.
+
'''Some useful analysis scripts:'''
−
* The red/blue lines (cavity on, right/left) should be roughly symmetric about zero. This reflects the fact that flipping the cavity polarization changes the sign of the asymmetry. (It's ok for there to be slight differences as above.)
+
* '''For PREX we should use: ''' <code>/home/compton/online/CompMon/dataQualityCheck.C</code> '''as our online macro!'''
−
* At the extremes (highest/lowest point) we should see an asymmetry greater than about 5%. (Here, we see extremes of about 8% and just over 6% for right and left.) If the asymmetry drops below 3%, we worry. Call an expert.
+
** As of now the way to run it is to navigate to the directory with the file and then running with <code>root -l dataQualityCheck.C\(<run number>,<tests flag>\)</code> We're looking into adding a simplified interface in the near future.
 +
The following macros were maintained by people who no longer work on the compton so use with caution:
 +
* /home/compton/lthorne/CompMon/plotAsymSpectrum.C: Quick and dirty view of asymmetry histograms, cavity and BCM limits.
 +
* /home/compton/lthorne/CompMon/buildQuartets.C and buildQuartetsPlot.C: For constructing multi-run asymmetry plots.
 +
** Run instructions are given in the comments at the beginning fo the file.
 +
* /home/compton/lthorne/CompMon/BCMCal/calibration<runNumber>,C: BCM calibration scripts for specific runs.
 +
* /home/compton/lthorne/CompMon/plotAccQuartets.C: plots sum, difference histograms for beam off, laser on, laser off for Acc0, Acc4.
 +
* /home/compton/franklin/CompMon/plotPulser.C: peek at DAQ pulser channels, including info on 'variable' and 'delta' for channel 13.  
  
−
==CIP Scan==
 
−
Getting good data sometimes requires a CIP (Compton interaction point) scan, where the beam tune is adjusted slightly in order to maximize its interaction with the photons in the cavity. Call a Compton expert to perform such a scan if:
 
  
−
* There has been a new beam tune through the Compton chicane.
+
'''Link to list of good Compton runs:'''
−
* The beam has been shut down for longer than an eight-hour shift.
+
−
* The photon counting rates drop drastically during steady running. (Compton rate (blue line) in strip chart -- see below)
+
  
−
=Compton Upgrade=
+
List of runs with comments, so know which ones were not junk.
  
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==Photon detector==
+
DVCS Google Docs: [https://docs.google.com/spreadsheets/d/1gSmgOaJW2azUDhhULDroP4eSpFxkn88YoFsQYNUVS1E/edit?usp=sharing Runlist] (Email Juan Carlos if you want to granted write permission)
−
The new photon detector crystal is a cylinder of GSO with a diameter of 6 cm and a length of 15 cm. It was installed in Hall A in December 2008.
+
PREX-CREX Google Docs: [https://docs.google.com/spreadsheets/d/13SW_Ya0zV5NDWxlS9A5FQ6b9YzpJw2fRNshcWm-noRA/edit?usp=sharing Runlist]  (Email Juan Carlos if you want to granted write permission)
  
−
In October 2008, the crystal was tested at incident photon energies of 20 MeV, 22 MeV, 25 MeV, 30 MeV, and 40 MeV. We are working on extracting the response function.
 
  
−
PREx requires an integrating DAQ system, which will run on a Struck FADC. We are currently commissioning this DAQ with a prototype FADC.
 
  
−
===Homing the photon detector table===
+
<!--  <small>''Last edit: ~~~~''</small> -->
−
You need to put the photon detector in the right position before you can take data: [[Happex_compton | How to home the table]]
+
  
−
===New DAQ flags file controls===
 
  
−
The FADC photon detector crl code lives in the franklin/crl directory.  To change the running mode, link a run file to the fadcScaler.flags file.  This is done by deleting the old fadcSclaer.flags file and then creating a link.  To do this, type:
+
=== Helicity controls ===
  
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    rm fadcScaler.flags
+
From within ''NewTools'' controls (see first few steps in [[Compton Photon Detector]] Compton GUI section):
−
    ln standardRun.flags fadcScaler.flags -s
+
# On far right of JTabs menu, there are "master" controls.  Find and click on Tools Screen.
 +
# Go to the helicity controls. (The default is delayed, so be careful of this.)
  
−
There are several different configuration flags files.  These are:
+
=== Current Scripts ===
  
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    standardRun.flags, for production data
+
As a brief check, run '''plotAsymSpectrum.C'''.  
−
    Etrigger.flags, for triggering the FADC on the electron detector
+
: [[Image:LTRun2565AsymNew.png|700px]]
−
    miniMegan.flags, for miniMegan LED pulser runs
+
−
    test.flags, for playing around
+
  
−
There are several flags which can be changed in the file. These are:
+
<!-- <small>''Last edit: [[User:Lthorne|Lthorne]] 16:35, 4 February 2016 (UTC)''</small> -->
  
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*readoutWaveformLength (number of samples read out per trigger, should be 100 for production data)
+
== PREX-II/CREX Compton Analysis ==
−
*readoutWaveformStart (sample to start read out -- trigger should be near 0, so -50 centers a pulse in a window of 100)
+
−
*maxStoredWaveforms (number of waveforms stored per MPS)
+
−
*maxStoredSums (number of sums stored per MPS)
+
−
*bitPMTtrig (1 means triggering on PMT signal)
+
−
*bitEDetTrig (1 means triggering on electron detector)
+
−
*bitPulserTrig (1 mean triggering on 10kHz pulser)
+
−
*bitMiniMegan (0 means LEDs not flashing, 1 means flashing)
+
−
*bitDelta (0 means delta LED not flashing, 1 means flashing)
+
−
*VarDACsetting (0 means variable LED changing pulse amplitude; set it to some value to leave it constant, 35200 corresponds to a 250mV signal on the scope in the counting house)
+
−
*numADCchan (number of FADC channels read out as sums; generally 1 for the GSO, 3 reads out the fingers also)
+
−
*prescaleTrig (prescale on the trigger for sums; 1 turns off prescale)
+
−
*prescaleRand (random prescale on the samples; 0 turns off random prescale, 4 means that every 4 samples is random in time)
+
  
−
(Courtesy of Megan Friend )
+
We've reworked the analysis to streamline finding the most important plots. We've adopted the analysis GUI used by panguin and other online monitors for Hall A experiments. To run, follow the steps below.
  
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== FADC DAQ ==
+
=== Online Analysis Steps and Checks ===
−
We are commissioning a new FADC-based DAQ for the photon detector. See [[Compton FADC DAQ|run information]].
+
  
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[[Compton analysis (for experts)|Help with analyzing data from the FADC DAQ]]
+
# Using the directions at the top of the page, open CODA and start a run.
 +
# Open a terminal and login using <code>ssh -Y compton@compton.jlab.org</code>
 +
# Enter command <code>gocompton</code>
 +
# First run compmon to analyze the run. To this use command <code>./compmon.sh -r <run number></code>
 +
# Once the run is finished analyzing and errors are logged, enter <code>source online.csh -r <run number></code>. This will create the plots in the GUI window.
 +
# Look at the plots in the following tabs:
 +
#* Snapshots: This window has one plot of snapshot peak height vs sum. Plot should look starkly linear. Plot also has the percentage of snapshots that pass an arbitrary selection criteria. I find healthy runs have about 80% of snapshots pass.
 +
#* Spectra: Plots compton spectrum broken down by beam and laser state. Is the compton edge where we expect it to be? Are Brem events low when beam or laser is off?
 +
#* Acc0: Plots of accumulator 0. Are they gaussian? Does the mean of the beam ON, laser ON plot differ from all the others?
 +
#* Acc0 vs Time: Plots of accumulator 0 value vs mps number. Are the accumulator values drifting significantly with time?Are beam trips readily noticeable?
 +
#* Asym and Polarization: Includes plots of the quartet sums, differences and asymmetry. Do they all look roughly gaussian? Are there no double-peaking effects? Does the calculated polarization yield some reasonable value?
 +
#* Asyms vs Time: Plots of the above vs time. Is there any significant drift in any of the quantities vs time?
 +
#* Asym Spectrum: '''As of 2019-07-31 this plot is not working. Background subtraction needs to be more carefully refined.'''
 +
# Once you click "Exit GUI" the same plots will be generated and saved to the [http://hallaweb.jlab.org/parity/prex/onlinePlots/comptonPlots compton plots web page] for easy review.
  
−
==Electron detector==
+
=== Making Custom Plots ===
 +
There are macros which make other compton plots which have been useful in the past, but are not being maintained anymore. To be certain, you can make your own plots to slake your curiosity. The following is description of CompMon output, the branches, as well as certain variables which you may find useful.
  
−
[http://spreadsheets.google.com/pub?key=p21FHudpawOtOCa6JDWdMfA Detector new event structure]
+
* General Variables: These variables may be found stored in multiple trees and should come in handy:
 +
** helicityStateReported: 0 for negative, 1 for positive
 +
** laserState: 0 for right-hand polarization and laser on, 1 for left-hand polarization and laser on, 2 for right hand polarization and laser off, 3 for left hand polarization and laser off, 4 for unknown state
 +
** beamState: 0 for beam off, 1 for beam on, 2 for unknown beam state.
 +
** cavPowerCalibrated: laser cavity power
 +
** bcm: calibrated BCM signal
 +
* mpswise: A tree of data stored per MPS
 +
** mpsCoda: MPS number
 +
** Acc#: Accumulator total for number #
 +
** NAcc#: Number of accumulator samples per MPS for accumulator number #
 +
** numTriggers: Number of triggered sums in current MPS
 +
* triggerwise: A tree of variables stored per trigger
 +
** sum: Total sum of trigger
 +
** sumIsRandom: 0 if sum is real, 1 if it is random
 +
* quartetwise: A tree of variables stored per quartet
 +
** PosHelAcc#: Sum of accumulator number # for positive helicity states in the quartet
 +
** PosHelNSamples#: Number of samples for accumulator number # for positive helicity states in the quartet
 +
** NegHelAcc#: Sum of accumulator number # for negative helicity states in the quartet
 +
** NegHelNSamples#: Number of samples for accumulator number # for negative helicity states in the quartet
 +
** quartetReportedHelicityPattern: Two different values, one for each valid quartet pattern
 +
* snapshots: A list of variables and snapshot readouts for each snapshot taken
 +
** numSamples: Number of samples in snapshots
 +
** snap: An array variable with numSamples entries that details the fADC readout of the snapshot
 +
* pulserwise: A tree of variables stored per pulser cycle. (SHOULD ONLY BE NEEDED BY EXPERTS)
 +
* runwise: A tree of variables stored per run. This tree only has one entry per leaf, and details info about pedestals.
 +
* epicswise: A tree of variables taken per EPICS event. These variables are also stored in other trees, so they can be accessed from there.
  
−
Webcams address
+
This is in addition to the inbuilt histograms produced in every CompMon output file. This should be more than enough to diagnose any compton DAQ problems.
  
−
Webcams were added to monitor the :
+
=Compton electron detector =
 +
== Compton new counting DAQ ==
  
−
*hacp2 [http://hacp2.jlab.org EthernetBlaster]
+
  A new event based counting Compton DAQ is being developped.
−
*hacp3 [http://hacp3.jlab.org webcam trigger]
+
−
*hacp4 [http://hacp4.jlab.org webcam on Beam Safety module, Front End power supply]  
+
−
*hacp5 [http://hacp5.jlab.org webcam on silicon strips detector current]
+
−
*hacp6 [http://hacp6.jlab.org APC]
+
−
** plug 1 Front End power supply
+
−
** plug 2 Webcam power supply
+
−
** plug 3 Webcam current
+
−
** plug 4
+
−
** plug 5
+
−
** plug 6 Ligh for viewer
+
−
** plug 7
+
−
** plug 8 Light for cameras
+
  
 +
It uses a VXS crate, the Intel CPU is acomp1.
  
−
How to reboot stuffs
+
It has 1 JLAB FADC250 in slot 10 VME address 0x500000, on SD and one VTP hostname hallcvtp in central slots.
 +
Currently there are 3 VETROCs in slot 13,14,15 respective addresses are 0x680000,0x700000,0x780000.
  
−
APC : [http://hareboot4 hareboot4]
+
To look at the VETROC rates, there is a diagnostic program /home/compton/camsonne/Edet2019/fe_diaggui
  
−
*plug 2 webcam
+
  DiagGUI ./ROC_compton_halla.txt
−
*plug 3 EPICS Edet
+
−
*plug 4 ETROC
+
−
*plug 6 FADC crate
+
  
 +
Make sure Clk sources are all 4 from SWB
 +
Issue a reset and the boards should be displaying rates
  
−
login hareboot4 using the usual password ( if you don't know it ask the run coordinator or a Compton expert )
+
one has to start the server on acomp1 in ~/linuxvme/diagguiserver : DiagGuiServer
  
−
select the outlet you want to reboot with the pull down menu "Immediate reboot"
+
Electron detector current webcam [http://comptcam4.jlab.org comptcam4]
  
−
and wait for the IOC to come back
+
Power cycle iochacp2 ( Compton Edet IOC ) port 2 [http://hareboot4.jlab.org hareboot4]
  
−
===Electron detector motion===
+
Power cycle Counting DAQ crate : log in [http://129.57.193.5] password for VXS crate
  
−
[[Compton Edet DAQ]]
+
[[Compton Counting DAQ Software HOWTO]]
  
−
=Compton Experts=
+
[[Compton EDet DAQ Cable Maps]]
 +
 
 +
[[Compton EDet DAQ RunList]]
 +
 
 +
= Compton Meetings =
 +
 
 +
See last list entry for most recent meeting.
 +
* [[Meetings before 2014]]
 +
* [[2014 Meetings]]
 +
* [[2015 Meetings]]
 +
* [[2016 Meetings]]
 +
* [[2017 Meetings]]
 +
* [[2018 Meetings]]
 +
* [[2019 Meetings]]
 +
* [[2020 Meetings]]
 +
* [[Wednesday, January 13, 2021, 4:00 pm EST]]
 +
* [[Wednesday, January 20, 2021, 4:00 pm EST]]
 +
* [[Wednesday, January 27, 2021, 4:00 pm EST]]
 +
* [[Wednesday, February 3, 2021, 4:00 pm EST]]
 +
* [[Wednesday, February 10, 2021, 4:00 pm EST]]
 +
* [[Wednesday, February 17, 2021, 4:00 pm EST]]
 +
* [[Wednesday, February 24, 2021, 4:00 pm EST]]
 +
* [[Wednesday, March 3, 2021, 4:00 pm EST]]
 +
* [[Wednesday, March 10, 2021, 4:00 pm EST]]
 +
* [[Wednesday, March 17, 2021, 4:00 pm EDT]]
 +
* [[Wednesday, March 24, 2021, 4:00 pm EDT]]
 +
* [[Wednesday, March 31, 2021, 4:00 pm EDT]]
 +
* [[Wednesday, April 7, 2021, 4:00 pm EDT]]
 +
* [[Wednesday, April 14, 2021, 4:00 pm EDT]]
 +
 
 +
= Current Compton Experts =
  
 
{| class="wikitable"
 
{| class="wikitable"
Line 199: Line 289:
 
! Expert
 
! Expert
 
! Phone
 
! Phone
−
! Pager
 
 
|-
 
|-
−
| Sirish Nanda
+
| Dave Gaskell
−
| x7176
+
| x6092
−
| 757-584-7176
+
 
|-
 
|-
 
| Alexandre Camsonne
 
| Alexandre Camsonne
 
| x5064
 
| x5064
−
| 757-584-5064
 
 
|-
 
|-
−
| Abdurahim Rakhman
+
| Ciprian Gal
−
| x5626  315-391-4622 (cell)
+
| x5324
 
|-
 
|-
−
| Megan Friend
+
| Juan Carlos Cornejo (Photon Detector)  
−
| 412-302-0576 (cell)
+
| x5282
−
|  
+
 
|}
 
|}
 +
 +
== Expert Information ==
 +
For expert monitoring and troubleshooting information please visit [[Compton Expert Information]].
 +
 +
= Photon detector Analyzer =
 +
Code can be found on github: https://github.com/JeffersonLab/HallA_CompMon
 +
JC says:
 +
The Makefile is ancient (since it has to work on old systems too) but there is an easy "fix".  In the src/config.d directory, create a file similar to cornejo_compton_jlab.conf but modify the paths respectively.
 +
Then run ./config config.d/<your_config_file>
 +
It will update the silly Makefile accordingly
 +
 +
Some old data and examples can be found on
 +
/w/halla-scifs17exp/compton/disk1/data/examples
 +
 +
= Old Compton page (pre-Spring 2016) =
 +
 +
See [[Pre-Spring 2016 Compton]]
 +
 +
 +
Last edit on {{REVISIONYEAR}} {{REVISIONMONTH}} {{REVISIONDAY2}}, by {{REVISIONUSER}}

Latest revision as of 06:14, 1 May 2025

The Hall A Compton

The Compton polarimeter is used to (non-invasively) monitor polarization of the incoming electron beam. It has three major components: an optics table with a laser that can lock to a Fabry-Perot cavity, an electron detector, and a photon detector to count scattered electrons and photons, respectively.

Last edit: LThorne 02:08, 24 February 2016 (UTC)


Shift Workers' Operation Guide

Start a Compton run every two hours.

The Compton DAQ is located in the back room in the Counting House. All commands are done from compton@compton.

If CODA is not already running:

Kill CODA first, then start it up again:
   $ kcoda
   $ startcoda
A few new Terminal windows and a GUI pop up.
LT CODAgui.png
Let "top" refer to the bar with named menu options near the top of the GUI (ex: Platform, Sessions, etc). Let "bottom" refer to the bar below "top" that contains a line of buttons (hover over them to reveal their labels; starting with "Configuration" on the left).
  1. In top, select: Platform > Connect
  2. In bottom, click on "Configuration" button.
    • If configuration listed in the "Run Parameters" box is not FADC_prod: in top, select Configurations > Cool and change it to FADC_Prod.
  3. In bottom, click on "Download" button
  4. In bottom, click on "Prestart" button
  5. When ready to start run, click "Start" button. Typical run duration: 2 hours. Type in any Start Of Run comments in the box. Click "OK" (even if you left comments blank!).
  6. When ready to stop run, click "End" button. Type in any End Of Run comments in the box. Click "OK" (even if you left comments blank!).

Information for Compton Experts

Troubleshooting

  1. HV on/off? -> Compton#High Voltage Controls
  2. Rebooting components: Compton Reboot
  3. [Experts only]: Correct parameters for run in integratingDAQ.flags and compton.params

Collimator Systems

What the jaws look like when placed at their lowest position, as seen on comptcam2. To view this camera follow this link and login with compton credentials.
  • Primary Lead Collimator
    • Presently left fully open at 20 mm diameter.
    • This is a 10 cm long collimator with inserts which can reduce aperture down to 10 mm or 5 mm in diameter.
  • Synchrotron Shields
    • For PREX-II a single 0.25 mm lead foil (painted) is taped to the front of the photon detector.
  • Compton Jaws
    • Remote access for experts can be found at [1]
    • Note, for the duration of the PREX-II running period, the Compton Tungsten Collimator System ("Compton Jaws") will not be used. It should be left it is's parked position of:
   aperture =   1.5 mm
   y center = -46.0 mm

Detector Positioning System

Date X [mm] Y [mm] Comment
2019-06-17 70 33.5 Visually Centered

Cameras

High Voltage Controls

LED System (Linearity Measurement System)

  • Will add info on MiniMegan soon

Taking an LED run:

  1. Find parameter file GUI:
   $ cd /home/compton/franklin/
   $ ComptonConfig
  1. Click "Pulser On, Pulser Trigger" on parameter file. Click "Apply", then "Done" to close GUI.
  2. Go to CODA. Start a new run to apply the settings. (This does not need to be a long run. You may end it immediately.)
  3. Start your LED run.
  4. When you go back to normal Compton runs: don't forget to turn the pulser off and do a short run to update the parameter file settings!

Laser System

Real time o-scope signals

Cavity lock camera

Make sure laser flipping is on

Turning off the laser

IOC reboot

Accessing the laser hutch in the hall

Laser and Locking troubleshooting

Software & Data Analysis

Relevant files, scripts, etc.

Run Compton analysis:

In compton@compton: 

   $ cd /home/compton/online/CompMon

Run analysis software: 

   $ ./compmon <run number, no brackets>

Open ROOT: 

   $ root -l /data/cmuwork/rootfiles/Fall2016/compmon_<run number, no brackets>.root

Run desired C script located in CompMon directory.


Some useful analysis scripts:

  • For PREX we should use: /home/compton/online/CompMon/dataQualityCheck.C as our online macro!
    • As of now the way to run it is to navigate to the directory with the file and then running with root -l dataQualityCheck.C\(<run number>,<tests flag>\) We're looking into adding a simplified interface in the near future.

The following macros were maintained by people who no longer work on the compton so use with caution:

  • /home/compton/lthorne/CompMon/plotAsymSpectrum.C: Quick and dirty view of asymmetry histograms, cavity and BCM limits.
  • /home/compton/lthorne/CompMon/buildQuartets.C and buildQuartetsPlot.C: For constructing multi-run asymmetry plots.
    • Run instructions are given in the comments at the beginning fo the file.
  • /home/compton/lthorne/CompMon/BCMCal/calibration<runNumber>,C: BCM calibration scripts for specific runs.
  • /home/compton/lthorne/CompMon/plotAccQuartets.C: plots sum, difference histograms for beam off, laser on, laser off for Acc0, Acc4.
  • /home/compton/franklin/CompMon/plotPulser.C: peek at DAQ pulser channels, including info on 'variable' and 'delta' for channel 13.


Link to list of good Compton runs:

List of runs with comments, so know which ones were not junk.

DVCS Google Docs: Runlist (Email Juan Carlos if you want to granted write permission) PREX-CREX Google Docs: Runlist (Email Juan Carlos if you want to granted write permission)



Helicity controls

From within NewTools controls (see first few steps in Compton Photon Detector Compton GUI section):

  1. On far right of JTabs menu, there are "master" controls. Find and click on Tools Screen.
  2. Go to the helicity controls. (The default is delayed, so be careful of this.)

Current Scripts

As a brief check, run plotAsymSpectrum.C.

LTRun2565AsymNew.png


PREX-II/CREX Compton Analysis

We've reworked the analysis to streamline finding the most important plots. We've adopted the analysis GUI used by panguin and other online monitors for Hall A experiments. To run, follow the steps below.

Online Analysis Steps and Checks

  1. Using the directions at the top of the page, open CODA and start a run.
  2. Open a terminal and login using ssh -Y compton@compton.jlab.org
  3. Enter command gocompton
  4. First run compmon to analyze the run. To this use command ./compmon.sh -r <run number>
  5. Once the run is finished analyzing and errors are logged, enter source online.csh -r <run number>. This will create the plots in the GUI window.
  6. Look at the plots in the following tabs:
    • Snapshots: This window has one plot of snapshot peak height vs sum. Plot should look starkly linear. Plot also has the percentage of snapshots that pass an arbitrary selection criteria. I find healthy runs have about 80% of snapshots pass.
    • Spectra: Plots compton spectrum broken down by beam and laser state. Is the compton edge where we expect it to be? Are Brem events low when beam or laser is off?
    • Acc0: Plots of accumulator 0. Are they gaussian? Does the mean of the beam ON, laser ON plot differ from all the others?
    • Acc0 vs Time: Plots of accumulator 0 value vs mps number. Are the accumulator values drifting significantly with time?Are beam trips readily noticeable?
    • Asym and Polarization: Includes plots of the quartet sums, differences and asymmetry. Do they all look roughly gaussian? Are there no double-peaking effects? Does the calculated polarization yield some reasonable value?
    • Asyms vs Time: Plots of the above vs time. Is there any significant drift in any of the quantities vs time?
    • Asym Spectrum: As of 2019-07-31 this plot is not working. Background subtraction needs to be more carefully refined.
  7. Once you click "Exit GUI" the same plots will be generated and saved to the compton plots web page for easy review.

Making Custom Plots

There are macros which make other compton plots which have been useful in the past, but are not being maintained anymore. To be certain, you can make your own plots to slake your curiosity. The following is description of CompMon output, the branches, as well as certain variables which you may find useful.

  • General Variables: These variables may be found stored in multiple trees and should come in handy:
    • helicityStateReported: 0 for negative, 1 for positive
    • laserState: 0 for right-hand polarization and laser on, 1 for left-hand polarization and laser on, 2 for right hand polarization and laser off, 3 for left hand polarization and laser off, 4 for unknown state
    • beamState: 0 for beam off, 1 for beam on, 2 for unknown beam state.
    • cavPowerCalibrated: laser cavity power
    • bcm: calibrated BCM signal
  • mpswise: A tree of data stored per MPS
    • mpsCoda: MPS number
    • Acc#: Accumulator total for number #
    • NAcc#: Number of accumulator samples per MPS for accumulator number #
    • numTriggers: Number of triggered sums in current MPS
  • triggerwise: A tree of variables stored per trigger
    • sum: Total sum of trigger
    • sumIsRandom: 0 if sum is real, 1 if it is random
  • quartetwise: A tree of variables stored per quartet
    • PosHelAcc#: Sum of accumulator number # for positive helicity states in the quartet
    • PosHelNSamples#: Number of samples for accumulator number # for positive helicity states in the quartet
    • NegHelAcc#: Sum of accumulator number # for negative helicity states in the quartet
    • NegHelNSamples#: Number of samples for accumulator number # for negative helicity states in the quartet
    • quartetReportedHelicityPattern: Two different values, one for each valid quartet pattern
  • snapshots: A list of variables and snapshot readouts for each snapshot taken
    • numSamples: Number of samples in snapshots
    • snap: An array variable with numSamples entries that details the fADC readout of the snapshot
  • pulserwise: A tree of variables stored per pulser cycle. (SHOULD ONLY BE NEEDED BY EXPERTS)
  • runwise: A tree of variables stored per run. This tree only has one entry per leaf, and details info about pedestals.
  • epicswise: A tree of variables taken per EPICS event. These variables are also stored in other trees, so they can be accessed from there.

This is in addition to the inbuilt histograms produced in every CompMon output file. This should be more than enough to diagnose any compton DAQ problems.

Compton electron detector

Compton new counting DAQ

A new event based counting Compton DAQ is being developped.

It uses a VXS crate, the Intel CPU is acomp1.

It has 1 JLAB FADC250 in slot 10 VME address 0x500000, on SD and one VTP hostname hallcvtp in central slots. Currently there are 3 VETROCs in slot 13,14,15 respective addresses are 0x680000,0x700000,0x780000.

To look at the VETROC rates, there is a diagnostic program /home/compton/camsonne/Edet2019/fe_diaggui 

 DiagGUI ./ROC_compton_halla.txt

Make sure Clk sources are all 4 from SWB Issue a reset and the boards should be displaying rates

one has to start the server on acomp1 in ~/linuxvme/diagguiserver : DiagGuiServer

Electron detector current webcam comptcam4

Power cycle iochacp2 ( Compton Edet IOC ) port 2 hareboot4

Power cycle Counting DAQ crate : log in [2] password for VXS crate

Compton Counting DAQ Software HOWTO

Compton EDet DAQ Cable Maps

Compton EDet DAQ RunList

Compton Meetings

See last list entry for most recent meeting.

Current Compton Experts

Expert Phone
Dave Gaskell x6092
Alexandre Camsonne x5064
Ciprian Gal x5324
Juan Carlos Cornejo (Photon Detector) x5282

Expert Information

For expert monitoring and troubleshooting information please visit Compton Expert Information.

Photon detector Analyzer

Code can be found on github: https://github.com/JeffersonLab/HallA_CompMon JC says: 

The Makefile is ancient (since it has to work on old systems too) but there is an easy "fix".  In the src/config.d directory, create a file similar to cornejo_compton_jlab.conf but modify the paths respectively. 
Then run ./config config.d/<your_config_file> 
It will update the silly Makefile accordingly

Some old data and examples can be found on 

/w/halla-scifs17exp/compton/disk1/data/examples

Old Compton page (pre-Spring 2016)

See Pre-Spring 2016 Compton


Last edit on 2025 05 01, by Gaskelld

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