1 / 5

Thoughts on Beam  Spectrometer Alignment

Thoughts on Beam  Spectrometer Alignment. Cooling channel alignment study (MICE notes 64 & 77) Solenoidal channels fairly forgiving Tolerance of FCs and CCs seems not to be too tight a few (3) mm a few (6) milliradians Specifying Focus Coils to 1mm and 1mr

melchior-magda
Download Presentation

Thoughts on Beam  Spectrometer Alignment

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Thoughts on Beam  Spectrometer Alignment • Cooling channel alignment study (MICE notes 64 & 77) • Solenoidal channels fairly forgiving • Tolerance of FCs and CCs seems not to be too tight • a few (3) mm • a few (6) milliradians • Specifying Focus Coils to 1mm and 1mr • These are random displacements and tilts wrt the nominal beam axis • The beam  spectrometer alignment may be different • Spectrometer defines and steers beam into the cooling section • Spectrometer has a large integral B.dl ~ 6Tm (4T x ~1.5m)

  2. Back of small envelope estimate Beam axis Displacement d Beam enters with offset d Fringe field gives pt kick Dpt = q v B d / 2 = 150 MeV/c dBz (centre) For 1 mm offset Dpt ~ 150 x 0.001 x 4 = 0.6 MeV/c at centre (max field ) cf 10 – 15 MeV/c rms (depending on emittance) d = 1mm not obviously very bad. Chris Rogers has studied this.

  3. Beam axis x Rotation q around y z Tilts may be more pernicious than offsets Tilt (= pitch or yaw) gives a small component of field perpendicular to axis, Bx = Bzq This is a dipole component seen by all muons in beam (how ring coolers work) Assume beam enters // to nominal beam axis At end of spectrometer py = q v Bxl = 300 MeV/c Bxl = 300 MeV/c Bzl q For 1 mr tilt py ~ 300 x 4T x 1.5m x 0.001 = 1.8 MeV/c (assuming l~ 1.5 metres) At exit of spectrometer 200MeV/c beam has been rotated (bent) by ~ 1.8/200 = 9 mrad. and offset transversely (i.e. in y) by Dy ~ lq / 2 ~ 9 x 1.5 / 2 ~ 7 mm 9 mr and 7mm are larger than FC and CC alignment tolerances wrt beam (6mr, 3mm) (and aiming for 1mr, 1mm) Any tilts of spectrometer solenoid must be << 1mr

  4. For a small tilt, bend angle where integral taken along z (beam) axis A reality check Last column is m0 NI in T-m (used 6 T-m on previous page) Expect greater sensitivity to spectrometer tilts than CC or FC tilts by factor 3 or 4

  5. Apparent (BOSE) requirement that spectrometer & beam are aligned by << 1mr looks tough • Implies sub-millimetre reproducibility / precision at each end • Some horizontal motion of beam with bends to correct may be possible? • Vertical motion would need correctors • Can my guesses be confirmed with ICOOL or G4MICE? • Could anyone do this? • Would require 3D field map • Comments, please

More Related