Synchrotron radiation suppression

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Synchrotron radiation suppression

• H. Burkhardt (CERN), W. Fischer (BNL)

RHIC Accelerator Physics Experiments Workshop,
BNL, 2 November 2006
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Aim of experiment

• Measure energy loss at moderately relativistic
  energies (g 100)
• Synchrotron radiation is dominate by rather soft
  photons (mm wave length), emitted in large cone
• In 1945 Schwinger predicted that low energy
  spectrum would be suppressed by presence of
  conducting materials (like beam pipe)

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Past experiments

• Measurements done at SPS (Pb) and HERA (p)
• Observe change in beam energy (revolution
  frequency) of debunched beam
• Beam looses energy due to synchrotron radiation
  and machine impedance, the second part can be
  filtered out by measuring at different energies
• Precision was not good enough to observe
  suppression effects
• SPS limited by vacuum (10-8 Torr)

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Estimate of effect
Energy loss from synchrotron radiation
Z2,makes heavy ions in RHIC particularly
interesting
H. Burkhardt, CERN
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Experimental conditions

• Au beams, low intensity, debunched (need to
  disable rf interlock)
• 2 hrs in coast, at 9.8, 31.2 and 100 GeV(ideally
  another higher energy, 70GeV)
• Stable magnetic fields (cold machine, stable
  except for persistent current drifts)
• Good vacuum (need 10-9 Torr, RHIC 10-11 Torr
  with low intensity, better than SPS)
• ? Observation of revolution frequency
  with time (with Schottky, need precision of
  10-5/hr)