Photon Beam Polarimetry

This page contains a list of to do items for installing the triplet polarimeter for the Spring 2015 GlueX run. Items that used to be on this page are now at the bottom in Items From Before January 2015

Expected Timeline

• February 2 - 5: Kei visits ASU (DONE)
• mid-February: ship triplet to JLab (DONE)
• End of February - mid-MarchApril: testing in EEL 126 (ONGOING)
• After initial testing: Survey by JLab
  • April 3 - May 4: physics beam, installation when possible

Drawings

• ASU polarimeter drawings

Hardware Progress

Slides are mostly what Kei shows at weekly ASU group meetings

• 2015/03/09 - 2015/03/18

Vacuum outgas test results (fits in red dashed lines are with linear functions)

• 2015/03/17 results with empty chamber (pdf)
• 2015/03/19 results with detector in chamber (pdf)
• 2015/03/25 Cabling of LV, HV, first signal (pdf)
• 2015/04/01 Cabling of signal channels, installation of motor (pdf)
• 2015/04/08 Connecting motor to controls, survey, install in hall (pdf)
• 2015/04/15 Installation in hall, Be foils, motor controls (pdf)
• 2015/04/22 Installation, noise reduction (pdf)

Hardware Division

• ASU
  • motor (data sheet)
  • controller
  • power supply
    1. 4 channels of +12V, 0.21 amps per channel
    2. 4 channels of -12V, 0.21 amps per channel
    3. 1 channel of +200V, the leakage current on the silicon strip detecter is 3.3 micro-amps
  • 32 short SSI cables with Lemo
  • vacuum rated limit switches (data sheet)
• JLab
  • fADCs
    1. 2 fADC250s on PSC VXS crate
  • 32 coax cables with Lemos on both ends (Fernando). Require 55ft to racks
  • turbo vacuum pump (Tim)
• Test setup in EEL 126
  • Fernando has spare fADCs, cables (not fire rated)
  • Kei will look for adequate sources
  • Tim can provide vacuum (would like ~30 mTorr)

Things to do at ASU

• packaging, shipping
• testing(?)

Things to do at JLab

• preparation of hardware before shipment
• installation
• Monitoring
  • Would like to run the device below 50 mTorr to avoid voltage breakdown. Need pressure sensor, monitoring (Note: this is being extremely cautious. We will be running at ~200V, and even with 300V the required pressure is, given d = 1mm, <6Torr)
  • Humidity: no requirements
  • Temperature: would like to monitor temperature in collimator cave since we don't want the preamps to get too hot. Need temperature sensor, monitoring
• testing with source(?) - will we test with source before installing in beam line?

Management/Safety

• write proposal, safety concerns/procedures
  • Current Triplet Installation Procedure Document pdf docx
  • Current Task Hazard Analysis Sheet pdf doc
  • Link to Task Hazard Analysis worksheet
  • Link to Beryllium handling procedure at JLab EH&S
  • example document for FCAL dark room (DOC)
  • Hall D Beam Line Vacuum Procedures document (PDF) - reuse (?) → Tim
  • example document for FCAL Hazard Analysis (DOC)
• Beryllium use:
  • will be used as radiator foil, 25μm thick
• Get approval from Bert
• Pass by Patritzia

Noise Levels

Slides are from Mike's presentation at ASU group meeting on February 11 2015.

• Expected noise levels are shown below (click to expand)
  • Modulation of baseline is due to our old HV supply, this should improve once we get JLab supply
  • Spikes are due to LV supply (not sure why, but spikes are seen on LIMO line)
  • There is also a switching noise that may be present at the ASU setup lab only
  • Signal from α source is large (~>500 mV), β source signal will only be several mV

Very low HV	Medium HV	High HV, signal shape

Analysis Procedures

• beam requirements
• requirements on other systems (PS, tagger)
• analysis procedure
  • Think of procedure for high-level analysis to ensure data is good
• online monitoring
  • fADC scalers for monitoring each sector → Hovanes
  • RootSpy plugin
• MC - GEANT4 simulation available with previous geometry

Items From Before January 2015

• Studies of some direct photon polarimetry possibility for the meeting on November 1, 2010
• Azimuthal asymmetries from Geant4 polarized pair production on January 10, 2011
• triplet polarimeter presentation at May 2012 collaboration meeting
• July 6 2012 teleconference regarding triplet polarimeter
• Monte Carlo code