Revision as of 15:28, 11 August 2014

General Information

• Goals
  1. Clean tune of the electron beam into the Tagger Dump
  2. Commissioning of the unpolarized photon beam
  3. Commissioning of the Hall D equipment under "soft" conditions:
     • low-intensity unpolarized photon beam <10 MHz/GeV at the endpoint
     • thin solid targets instead of the regular liquid hydrogen target
     • solenoid current 1200 A instead of the nominal 1300 A
• Schedule and Hall Availability: The accelerator run is scheduled for 19-Sep-14 - 22-Dec-14. 3 week are assigned for Hall D commissioning with photon beam (see [1]). The tentative plan is:
  1. Accelerator: beam recovery and 5.5 pass beam tune to the dumplette Sep 19-29. Hall D/Tagger are open.
  2. Accelerator: electron beam tune to the Tagger Dump, 29-Sep-14 - 03-Oct-14. Hall D/Tagger are locked. TAGM and the electronics are removed from the Tagger Hall.
  3. Accelerator/Hall D: Photon beam tune to Hall D and the initial equipment checkout, Oct 4-5. Halls are locked.
  4. Hall D: Re-installation of the Tagger equipment (TAGM and the electronics), Oct 6-11. Halls are open.
  5. Hall D: Equipment commissioning with photon beam, Oct 12-31. Halls are locked.
• Expected Staffing:
  • Run Coordinator: Alexandre Deur
  • Online Shifts: 3 persons per shift, one with solenoid training.
  • Offline Shifts: at least two people looking at data written to tape.
• Coordination Activities:
  • MCC meetings at 7:50am and 8:00am
  • Daily run meeting broadcast on bluejeans 10:30am?? Meeting will be in the counting house conference room.
  • Links to accelerator schedules:
    • CEBAF 12 GeV Commissioning calendar
    • Scheduled Accelerator Down (SAD)/Maintenance Calendar
    • http://accboard.acc.jlab.org/
• Activity Priority
  • High: Activity should be completed, contingencies in place for issues.
  • Medium: Desirable to complete the activity.
  • Low: Activity would be useful if time permits us to do it.
• Activities planned for the next run in Spring 2015:
  • Installation of liquid hydrogen target.
  • Installation of diamond radiator in goniometer.
  • Running at 1300A solenoid current.

Beam Configuration Parameters

• Energy of Beam: expected ~ 10.5 GeV
• Beam current:
  • Electron beam tuning is done with pulsed beam 4-10 µA, duty cycle 1.5%, average current 60-150nA (see beam description here)
  • Photon beam operations: CW 50-200 nA
• Radiators:
  • 1.5 µm Al (1.7·10^-5 R.L.)
  • 10 µm Al (11·10^-5 R.L.)
  • 30 µm Al (34·10^-5 R.L.)
• Collimator hole: 5 mm diameter
• Targets. Diameter = 3.19 cm. The position of the target can be moved 12 cm downstream to 32 cm upstream relative to the nominal Hall D target position (60 cm downstream of the downstream end of the upstream solenoid endcap.)
  • 10mm thick disk of CH₂ (HDPE, high density polyethylene, density 0.93-0.97 g/cm³ ), 0.95 g/cm², ~1.2% R.L.
  • 2mm thick disk CH₂ (HDPE)
  • 2mm thick inside a 20mm diameter area and 7mm thick outside (HDPE)
  • 3.4mm thick graphite disk, 0.75 g/cm², 1.8% R.L.

Run Plan

Tune Electron Beam

Tune Photon Beam

One Week Pause in Running

Collect Beam Data for Detector Checkout

Optimize Detector Settings

Drift Chamber Alignment

Collect More Regular Data