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Target/Beam Interaction MICE Target Workshop – RAL 8/1/2009

Target/Beam Interaction MICE Target Workshop – RAL 8/1/2009. M. Apollonio, A. Dobbs - IC. Motivations:. optimise secondary production minimising dangerous losses in ISIS assess better orientation/shape of the shaft for secondary production a work at “four hands”:

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Target/Beam Interaction MICE Target Workshop – RAL 8/1/2009

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  1. Target/Beam Interaction MICE Target Workshop – RAL 8/1/2009 M. Apollonio, A. Dobbs - IC

  2. Motivations: • optimise secondary production minimising dangerous losses in ISIS • assess better orientation/shape of the shaft for secondary production • a work at “four hands”: • A. Dobbs, ORBIT simulation of ISIS ring / interaction with target / comparison with data taken from MICE shifts, • MA, G4Beamline simulation of secondary production with a set of shafts

  3. ORBIT Results A. Dobbs

  4. - overview of results obtained from simulating beam loss in ISIS synchrotron • - using code ORBIT • - emphasis to loss caused by MICE target • - results for 3 target orientations: • long-thin • short-fat • tilted or parallel to the MICE beamline - 2 target sizes are used: • 10mm x 1mm and • 1mm x 1mm - dip depths ranging from 27mm to 24mm above beam axis are shown.

  5. Target Orientations (variable depths) • “Long-Thin” – 10mm along z – axis, 1mm along x – axis (true orientation) y s x • “Short-Fat” – 1mm along z – axis, 10mm along x - axis • “Reduced” – 1mm along z – axis, 1mm along x - axis

  6. Model The MICE target is modelled as a block of iron inserted into the ISIS beam 2ms before extraction, sitting at a position of ~115m around the synchrotron ring. The target is also currently modelled as being static. Work is being done about the possibility of improving the model to make the target titanium and dynamic. NB: ORBIT phys.models elastic/inelastic/nuclear

  7. TGT

  8. Results • 2D histograms showing number of particles lost from the beam as a function of time in an ISIS spill and the position in the synchrotron in which they were lost. • Further a table is also presented for each target configuration, showing the number of “hits” (intersections of the volume) in the MICE target, for the last 2ms of the ISIS spill • The tables also give the number of particles “absorbed” by the target i.e. turned into lost particles by their interaction with the target.

  9. Short-Fat: 27mm above axis, -1 to 10ms Injection losses MICE target losses MICE target losses zoom last 2 ms

  10. Short-Fat: 27mm above axis, 8 to 10ms

  11. Long-Thin: 27mm above axis, -1 to 10ms (NB: present config)

  12. Long-Thin: 27mm above axis, 8 to 10ms

  13. Long-Thin: 26mm above axis, -1 to 10ms

  14. Long-Thin: 26mm above axis, 8 to 10ms

  15. Long-Thin: 27mm above axis, 250 rotation, -1 to 10ms

  16. Long-Thin: 27mm above axis, 250 rotation, 8 to 10ms NB At present there remains an ambiguity in the direction of the rotation, clockwise or anti-clockwise. If / when this is resolved it will be published in an updated version of this document.

  17. Reduced: 27mm above axis, -1 to 10ms

  18. Reduced (1mm^2): 27mm above axis, 8 to 10ms

  19. Reduced: 26mm above axis, 8 to 10ms

  20. Reduced: 25mm above axis, 8 to 10ms

  21. Reduced: 24mm above axis, 8 to 10ms

  22. Circular-solid 6mm radius: 27mm above axis, 8 to 10ms

  23. SUMMARY of the SUMMARIES • - in a sh.fat config. losses happen far from the tgt point • the long-thin (or cylindrical) config. suggest most of losses happen in S7-8, closer to the TGT prod point - more controllable with collimators/scrapers?

  24. G4Beamline Studies M. Apollonio

  25. is there a better shape for the target or orientation? • how many secondaries (pi) do we get at the Q1 bore (per impinging proton?) • what about materials? Q1-2-3 ISIS p trajectory 25o MICE TGT

  26. Q1-TGT axis Z X 25 deg 10 mm 10 mm B A A 25 deg rotation & propagation to plane B LONG SLIM secondaries production 20<theta<30 propagation to plane A acos(Pz/Ptot)>20 && acos(Pz/Ptot)<30 to Q1 lost C shift & align with Q1-TGT axis

  27. 25 deg 25 deg FAT SHORT TILTED TGT 10o / 25o

  28. Materials: Ti Be Al 25 deg Cylinder: OD=6mm/ID=4.7 mm

  29. Tgt_long_slim_rot0: y:x Nprimaries=100M A

  30. Tgt_long_slim: y:x rotation 25 deg + shift 4.226 B

  31. at Q1 planein Q1 bore C

  32. Tgt_tilt25_rot0: y:x Nprimaries=100M A

  33. C At Q1 planeQ1 bore

  34. Tgt_short_fat_rot0: y:x

  35. Tgt_cyl_rot0: y:x

  36. CONCLUSIONS - neither the shape nor the orientation of a target seem to alter significantly the production of secondaries to Q1 • the overall material volume intercepted by the beam is the main parameter (reasonable) • material other than Ti (lower A/rho) generate less secondaries (in particular pions) • a good balance should be found between weight / mechanical stiffness / and pion production • a hollow cylinder is a good solution, certainly does not worsen the performances of the present configuration

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