Difference between revisions of "20190520-Optics-Mtg"

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== Agenda ==
 
== Agenda ==
 +
* Draft optics run plan by Seamus [https://prex.jlab.org/cgi-bin/DocDB/private/ShowDocument?docid=378 pdf]
  
 +
* Sorry I have not read Seamus's plan yet; I will by the meeting, but here is mine:
 +
 +
<pre>
 +
  PREX Optics Run Plan -- Draft from Bob M.
 +
 +
Pre-Run
 +
=======
 +
 +
1. Check polarity of the magnets and actually know what
 +
  you're doing.  I've seen this wrong a lot!
 +
 +
2. Set up the magnets.  Here we need to know nominal currents
 +
  as function of moment for septum, Q1, Q2, dipole, and Q3.
 +
  And *WE* need to know this, not rely on other people.
 +
 +
3. Check VDC alignment and pinning.  Assumptions important for
 +
  interpretation of correct septum setting.
 +
 +
4. Prepare simulation results for questions at run-time (see
 +
  below).  In short, we need the simulated sieve slit pattern,
 +
  the acceptance function, and predicted behaviour for mistunes.
 +
 +
Run-time
 +
========
 +
 +
1. Establish beam -- standard procedure.
 +
      calibrate BPMs, HARP scans
 +
 +
2. Target alignment with Carbon hole target
 +
 +
3. Put in Tantalum target.
 +
 +
4. Put sieves in, set the magnets for nominal momentum.
 +
 +
  See the sieve holes ? 
 +
 +
        If "yes", good, can optimize.  Check versus simulation
 +
        if the acceptance is reasonable. 
 +
 +
        If "no": something wrong!  Probably a wrong polarity(s),
 +
        See Pre-Run step 1.
 +
 +
4. For the momentum scan, leave the septum alone. 
 +
  Vary the momentum in steps of size 0.5% from -2.0% to +1.0%.
 +
  This is used for the optimization of the transfer tensor.
 +
 +
5. Septum tuning.  The central ray (5 degree, delta=0) should hit
 +
  the center of the focal plane.  Mistune the septum by +/- 5%.
 +
  Predict the shift (of order 1 cm and 10 mrad ??), compare to
 +
  simulation.  Repeat with +/- 10%.
 +
 +
6. Quad scans:  Need a detailed plan because it could be time
 +
  consuming, but I'm thinking mistunes of order 10% and we
 +
  want to compare offline to simulation to check our model.
 +
  Note, a wrong quad setting can reduce the acceptance or
 +
  change or distort the spot on the detector.
 +
 +
7. Measure the acceptance function and compare to simulation.
 +
</pre>
  
 
== Minutes ==
 
== Minutes ==

Latest revision as of 10:51, 20 May 2019

Back to Main Page >> HRS_Optics_Mtg


previous meeting << >> following meeting

Logistic information

 BlueJeans calling instructions:
 Toll-Free Number (U.S.&  Canada):  888-240-2560
 International toll number:         408-740-7256
 PARTICIPANT CODE:                  #9989030149
 Room IRL:                            <none>


Agenda

  • Draft optics run plan by Seamus pdf
  • Sorry I have not read Seamus's plan yet; I will by the meeting, but here is mine:
   PREX Optics Run Plan -- Draft from Bob M.

Pre-Run
=======

1. Check polarity of the magnets and actually know what
   you're doing.  I've seen this wrong a lot!

2. Set up the magnets.  Here we need to know nominal currents
   as function of moment for septum, Q1, Q2, dipole, and Q3.
   And *WE* need to know this, not rely on other people.

3. Check VDC alignment and pinning.  Assumptions important for
   interpretation of correct septum setting.

4. Prepare simulation results for questions at run-time (see 
   below).  In short, we need the simulated sieve slit pattern,
   the acceptance function, and predicted behaviour for mistunes.

Run-time
========

1. Establish beam -- standard procedure.
      calibrate BPMs, HARP scans

2. Target alignment with Carbon hole target

3. Put in Tantalum target.

4. Put sieves in, set the magnets for nominal momentum.

   See the sieve holes ?  

        If "yes", good, can optimize.  Check versus simulation 
        if the acceptance is reasonable.  

        If "no": something wrong!  Probably a wrong polarity(s),
        See Pre-Run step 1.

4. For the momentum scan, leave the septum alone.  
   Vary the momentum in steps of size 0.5% from -2.0% to +1.0%.
   This is used for the optimization of the transfer tensor.

5. Septum tuning.  The central ray (5 degree, delta=0) should hit
   the center of the focal plane.  Mistune the septum by +/- 5%.
   Predict the shift (of order 1 cm and 10 mrad ??), compare to
   simulation.  Repeat with +/- 10%.

6. Quad scans:  Need a detailed plan because it could be time
   consuming, but I'm thinking mistunes of order 10% and we
   want to compare offline to simulation to check our model.
   Note, a wrong quad setting can reduce the acceptance or 
   change or distort the spot on the detector.

7. Measure the acceptance function and compare to simulation.

Minutes