Difference between revisions of "L-HRS for SBS"

Revision as of 16:51, 7 June 2021

The Left HRS will be used during the SBS era for calibrating HCAL and possibly for a hypernuclear experiment. Here's a talk about it: http://userweb.jlab.org/~rom/LHRS_BobM_17May21.pdf

Running Left-HRS DAQ

Currently we can only run the DAQ in a standalone configuration. Eventually, we will connect it to the SBS DAQ.

update: June 7, 2021

Where to run:  adev account on adaq1.  

I. Bringing the DAQ up from scratch.

  1a. Might need to reboot crates, but probably NOT.
  1b. Might want to kcoda, although startcoda does that.

  2. Type "setupxterms", this pops up 4 xterms

    Might be a good idea to do it from adaq2 because kcoda kills xterms.
    Alternatively you can do the commands in #3 by hand in windows.

  3. In each xterm or window, login.  Note, we now use adev !!

     The old TS is not used in the DAQ; however, it houses scalers
     which are read for xscaler and the usual event type 140 insertions.

       VXS crate with FADC .....  ssh -X halladaq8 -l adev
       lower fastbus crate .....  ssh -X lhrsfb1 -l adev
       middle fastbus crate ....  ssh -X src2 -l adev
       uppper fastbus crate ....  ssh -X lhrsfb2 -l adev

    (if you don't know the password, text Bob)

  4. Startcoda by typing "startcoda"

  5. In each window (step 3) type the appropriate "startrocN" command

	   ROC1-hallada8:  ./startroc1
           ROC2-lhrsfb1: ./startroc2
           ROC3-src2: ./startroc3
           ROC4-lhrsfb2 :  ./startroc4

     You should see the ROCs connect in the red gui (platform).

  6. Now in Run Control GUI (aka rcgui)
 
  Control(upper left)-> Connect -> click the tools thingy (Configure).

     Sometimes one component is disconnected or has a problem (red),
     like "configuring" instead of "configured".
     Often a reset ( <| in gui ) does the trick, and download again.
     Otherwise patiently start at 1.  It works eventually.

  Assuming you can see connected ROCs in the rcgui:  

     Next, Download, StartRun.  If you don't know what a button
     means, let the mouse hover over it for a few sec.

     Configs to use.  Note, the last correctly-running config is what
     gets loaded by default.  You have two configs to pick:

      LHRS -- all 4 crates

      LHRS_FADC -- just the FADC, good choice if Fastbus is down and
                   you don't need Fastbus

  ---------------------------------------------------

II. If CODA running somewhere and you just want to start/stop runs.

      Type "rcgui" and start with point 6 above. 

  -----------------------------------------------------

II. Trouble shooting

     Might need to power-cycle the crate if you things like this:

         ./startroc1: line 2: 31770 Segmentation fault 

   Old ROC processes can cause trouble.  Kill them or reboot.
   
ps awx | grep roc
21353 ?        Sl     0:00 coda_roc -type ROC -name ROC3s
21394 ?        Rl    44:36 coda_roc -type ROC -name ROC3
21477 pts/0    R+     0:00 grep roc
[root@src2 ~]# kill -9 21353 21394

     Some other component not working (e.g. PEB error).
     Be patient, go to I.1 above.  

III.  Power cycling can be done remotely.

     ROC1 (formerly ROC31 during PREX) FADC crate
     go to bbvme1.jlab.org   on firefox on a-onl@aonl1

     For the Fastbus, the hall A Tools screen and "Crate resets"
     used to work, but during the shutdown I have had trouble finding it.

Commissioning Plan for Left HRS

Before we use the Left HRS to commission HCAL, we need to spend some time checking the HRS itself. Most checks of detector and the DAQ can be done with cosmics or with pulsers, but the two topics where we need beam are: 1) Check the HV on the Cherenkov detectors (particles need to go in the right direction, and 2) Check the magnetic optics (we can start with an optics database from the Tritium era.

Initially we'll have the HRS at about 90 degrees. We can run with beam and check detectors and look at reconstructed angles at the target. We can do this parasitically or late at night when nobody is in the hall. (We need the beam on target.). For the reconstructed angles, all is well if the acceptance looks about right (a familiar rectangle) and we can compare to Monte Carlo. Later, when we remove Bigbite, we can put in the sieve slits and check more carefully the optics. If the optics are really bad (blurry hole pattern) we can do an optics calibration run plan. However, I doubt that this is necessary.

Rate calculations for e-P elastic scattering.
Assuming 15 cm LH2 target.  1 uA of beam.

Here I used some of the kinematics given in the HCAL run plan.
4.4 GeV is not very practical.
Note, the sieve slit will cut the rate by a factor of 200.

E' is the momentum setting of the L-HRS for elastic.

   E     theta_HRS     E'       Rate
  (GeV)  (degrees)   (GeV)      (Hz for 1 uA beam)

  4.4     30.9      2.64       2.9 Hz/uA
 
  4.4     34.1      2.44       1.3 Hz/uA

  4.4     61.1      1.29       0.018 Hz/uA

  4.4     64.3      1.20       0.014 Hz/uA

  4.4     67.5      1.13       0.010 Hz/uA

  4.4     70.7      1.06       0.008 Hz/uA

  2.2     30.9      1.65       216 Hz/uA ..... angle available when Bigbite removed (can run with sieve)

  2.2     34.1      1.57       100 Hz/uA

  2.2     40        1.42       29 Hz/uA

  2.2     45        1.30       11.7 Hz/uA

  2.2     80        0.75       0.27 Hz/uA  .... run here at 40 uA (without sieve)

  2.2     90        0.66       0.15 Hz/uA