Polarimeter Documentation

C-GEN Polarimeter Design / Documentation

• (18 Sept 2014) JT2go 3D model (based on working model in JLab CAD system; Contact: Paulo Medeiros)
  • JT2go viewer (Windows)
  • Hall layout w/ mock-up of Magnets and "Plan B" detector using 160cm bars (JT file)
  • Images extracted from the above JT file:

• 

  File:Top-with scale-18Sep2014.pdf

• 

  File:Top-with scale midplane cut-18Sep2014.pdf

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  File:Side-isometric-18Sep2014.pdf

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  File:Side isometric-midplane cut-18Sep2014.pdf

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  File:Side-isometric no mag1-18Sep2014.pdf

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  File:Side isometric no mag2-18Sep2014.pdf

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  File:Top isometric midplane cut-18Sep2014.pdf

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  File:Top zoomed-out-18Sep2014.pdf

Possible scintillator hardware

The "Plan B" design requires:

• Total: 136x 10 cm x 10 cm "thick" bars

108   10 cm  x 10 cm x 160 cm   E counters (top + bottom)
 28   10 cm  x 10 cm x 160 cm   analyzer bars

• Total: 80x 1 cm x 10 cm "thin" bars

 52    1 cm  x 10 cm x 160 cm   dE  (top + bottom)
 28    1 cm  x 10 cm x 160 cm   analyzer vetos

• All bars are double-ended readout.

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Existing Scintillator Bars

BLAST bars (some from PSI LADS detector)

 Ohio walls: 16x      10 cm x 22.5 cm    x 400 cm  <-- these are the ones we are principally interested in
 LADS15:     28x      15 cm x 14.5 cm(*) x 160 cm
 LADS20:     28x      20 cm x  9.8 cm(*) x 160 cm
 (*) bars are trapezoidal shaped; this is mid-point thickness

• Availability: Yes (we have a promise that the Ohio walls are ours; they can remain at MIT for the time being. A trip to take a look at them and confirm their condition would be wise.)
• Location: BATES
• Contact: Michael Kohl / Bob Redwine (MIT)
• References: NIM A 603 (2009) 247–262 (BLAST detector), NIM A 373 ( 1996) 374-38 (PSI LADS reference)
• Notes:
  • Bars would need to be cut and polished (Kent State?).
  • New PMTs are likely.
  • Primarily interested in the Ohio walls.
    • The LADS bars are trapezoidal; they can be stacked into planes by alternating the 'wedge' direction. Not even sure if they are available as well(?)

"BigBite" HAND

 32x   10 cm x 10  cm  x  100 cm
 32x   10 cm x 12.5cm  x  100 cm
 12x   10 cm x 15  cm  x  100 cm
 12x   15 cm x 25  cm  x  100 cm
 32x    2 cm x 11  cm  x  100 cm

• Availability: Yes
• Location: JLab ESB
• Contact: Doug Higinbotham
• Reference: Wermus Tech Note
• Notes:
  • These are available now
  • Will likely need to replace most of the (3") PMTs

GEn E02-013 BigHAND neutron array

UVa:      100x     10 cm x 10 cm x 160 cm
Glasgow:   24x     10 cm x 20 cm x 180 cm
CMU:      120x      5 cm x 15 cm x 180 cm

• Availability: ??? (there are plans to use the BigHAND array in Hall A)
• Location: Bldg 64 (tent at NE corner of Accel area)
• Contacts: Mixed: UVa (Donal Day), CMU (G. Franklin?), Glasgow (J. Annand); Bogdan, Albert (JLab)
• Reference: BigHAND Geometry], General Documentation]
• Notes:
  • These are still stored in the BigHAND cartridges in Bldg 64
  • PMT status TBD
  • At our 2013 collaboration meeting Donal mentioned the UVa bars are still available and are still under UVa ownership.

Existing Material at Kent State

8x  10 cm x 51 cm x 100 cm   (actual dimensions: 4" x 20" x 40")
3x  10 cm x 25 cm x 100 cm   (actual dimensions: 4" x 10" x 40")

• Availability: Yes
• Location: Kent State
• Contacts: Bryon Anderson
• Reference:
• Notes:
  • Needs cutting and polishing
  • PMTs needed

Existing bars within Collaboration

SUNO    (Mostafa Elaasar):   ??x   1 cm x 10 cm x 100 cm
La Tech (Steve Wells):       ??x  10 cm x 10 cm x 100 cm

• Availability: Yes
• Notes:
  • Purchased as test bars with an eye to incorporation into full polarimeter
  • PMTs are included

Miscellaneous

• Calibration of a neutron polarimeter in the 0.2–1.1 GeV region [NIMA557 (2006) 585-593]: File:JLAB-PHY-06-461.pdf

Simulation Codes

The collaboration has work space at /work/hallc/c-gen/ (accessible on the ifarm machines).  
Contact Brad Sawatzky <mailto:brads@jlab.org> for write access.

Using the JLab Farm

• Quick Start page here: https://scicomp.jlab.org/docs/getting_started

• Environment setup information for ROOT/G4 etc is here: https://data.jlab.org/

• Basically, run a few short test jobs on an interactive node (ie. ifarm65.jlab.org) just as you would on your desktop.
  • Source code and binaries can reside in your /home directory. (If space is an issue, let me know.)
  • Large output (*.root) files must be written to /volatile/hallc/cgen/<your_jlab_username>/
    • Note the delete policy for the /volatile file system here: https://scicomp.jlab.org/docs/volatile_disk_pool
    • Basically, if it's something that we want for long term, then you must push it to tape and access it through the /cache filesystem.)

• Once the code is working, then generate a control script for a batch job and submit it using 'jsub': https://scicomp.jlab.org/docs/jsub
  • There are a number of examples here: https://scicomp.jlab.org/docs/auger_examples
  • A few parameters you'll need are:

 PROJECT : cgen
 TRACK   : simulation
 OS      : centos65

• Note the best practices / FAQ here: https://scicomp.jlab.org/docs/batch_job_faq

• Watch jobs in the queue here: http://scicomp.jlab.org/scicomp/#/auger/jobs

• Large file transfers to/from your institution work well with Globus: https://scicomp.jlab.org/docs/node/23
  • You can set up a local 'endpoint' on your machine and this system can take care of shuffling large files around, retrying if needed, synchronizing directories, etc. ('scp' works too, of course.)

GEANT4 Simulation

[NMU-NPOL]: (Github) GEANT4 model developed by W. Tireman et al. (NMU)

• Some discussion of this code may be found in this [talk]
• We are using git for version control. [Learn how to use it!]

FLUKA + MCEEP

• Andrei Semenov (U of Regina) has a simulation using Fluka 2011.2.9 + MCEEP-generated neutrons. Contact Andrei for details.

JLab

• Pavel Degtiarenko (JLab) was contacted in Sep 2014 regarding any local codes that might be useful. Unfortunately nothing really suitable is available at the moment. The old GEANT3 model is still used for dose related calculations. A planned G4 model has (tentatively) been replaced by a future FLUKA model -- neither is in a useful form yet.