Bubble Chamber Beam Test May 2018

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Beam Setup and Measurement - May 2018

Bubble Chamber Turn On

  • Fill with natural C3F8 – test bubble chamber systems operation


  • With beam on bubble chamber radiator:
  1. How does CCD camera perform under beam-on conditions?
  2. Count rates on bubble chamber. Do we get single or multiple bubbles from Bremsstrahlung beam exposure?
  3. Measure gamma ray beam spatial profile as reflected by bubble distribution. Is collimator effective in defining the gamma-ray beam?
  4. Test the bubble chamber laser shutter (gumby shutter)


  • Background measurements:
  1. Measure beam off environmental background in chamber-injector area
  2. Measure beam on background by looking outside fiducial volume
  3. Measure background with beam to Faraday Cup in CEBAF beamline (about two meters from chamber)
  4. Measure neutron events in chamber. Neutron radiation detectors in injector region will indicate if any neutrons are generated



Bubble Chamber Beam Test

  • Bubble Chamber Run Plan
Draft Run Plan: media:bubble_runplan.pdf
Systematics:media:bubble_systematics_May2018.pdf
(Joe) Dispersive and Non-Dispersive Optics for last week's beam study data


Run Plan:

  • Prebeam Checkout:
  1. Neutron source test at 0.7, 1, 2, 5m
  2. Establish background rate with no beam


  • Check if Bubble Chamber is working properly:
  1. Establish high rate checkout beam: 5.74 MeV/c, 1uA (1 event per 5s)
  2. Determine the initial operational pressure and temperature
  3. Establish fiducial region for beam
  4. Measure activity with beam in high pressure
  5. Move beam +/-3 mm and search for 10% lower rate
  6. Change spot size to 2, 3mm; observe 30% lower rate at 3mm
  7. Current scan: 0.5 uA for 1 hour, 0.25 uA for 2 hours
    1. Normalized yields should be identical


Beam Momentum (MeV/c) Beam Kinetic Energy (MeV) Beam Current (µA) Time (hour)
5.24 4.75 50 31
5.34 4.85 50 40
5.44 4.95 20 13
5.54 5.05 10 6
5.64 5.15 4 3
5.74 5.25 1 3


  • Presentations
  • MCC 8 am presentation