Permanent Magnet for IPM

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Permanent Magnet for IPM

• NdFeB- less expensive, less stable(SLAC)
• Sm2-Co17- High field, expensive, radiation
  effect(DTL)
• Strontium Ferrite-low field,less expensive (FNAL)
• delB/B lt 0.05 for 5 50 deg C With Nife tem
  compensation (-0.2/C)
• delB/B lt1 for 1 E9 rad (1w/m 3.4 e6 rad/y)
• delB/B lt0.02 per year

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Requirements for the IPM Magnets

• the magnetic filed be such that the Larmor radius
  (REm/qB2) should be less than the spacing
  between collector anodes
• the magnetic filed line should be straight line
  i.e the line transverse runout should be less
  than the spacing between collector anodes

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Magnets Arrangement for IPM
0.3 m
0.3 m
0.4 m
0.5 m
0.5 m
2.0 m
 
For SNS beam 1 GeV, magnet length should be 40 cm
and filed 0.1 T. Which give a kick to beam about
8 mrad. To correct this kick, there are two other
magnets that correct the closed orbit. The
arrangement of this magnet is shown in figure.
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RICH Permanent Magnet for IPM
The parameters for the RICH IPM are magnetic
length30cm, magnetic filed0.14 T, spacing
between collector anode. 0.6 mm, number of
channels64, Larmor radius0.54 mm.
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B3 in Rich PM
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B5 in RICH PM
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Advantages/Disadvantages of PM

• Low cost
• Multi-poles might be ok
• If one out of six (3 in each plane) goes bad due
  to some reason (e.g. beam scraping, temperature
  variations) machine wont work
• (It will take only 7 change in the change in the
  magnet filed (since this magnet does not use NiFe
  alloy to stabilize the thermal coefficient) to
  produce 1 cm close orbit distortion. )

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Advantages/Disadvantages of EM

• (1) it is off during the production run and all
  the errors due to these magnets are not there
  when IPM is not used.
• (2) The electromagnet can be design with much
  better field quality like rest of the magnet in
  the ring while satisfying all the requirements
  for IMP.
• (3) There is no temperature dependence, and
• (4) there is no ageing affect.
• (1) cost more, and
• (2) since it is turn on only during the profile
  measurement, it may not measure the true beam
  profile.