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Measuring Multiple Scattering in Step IV: G4MICE Results and Methodologies

This document discusses the measurement of multiple scattering (MS) in Step IV of the G4MICE experiment, focusing on new results from the latest simulations. We explore discrepancies in predictions of scattering angles using standard PDG expressions and propose innovative methods utilizing trackers for direct measurement of MS. Key comparisons between different materials (LiH and LH2) are detailed, along with analysis of smearing effects on particle vectors. This work is crucial in refining scattering predictions and enhancing our understanding of particle behavior in various materials.

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Measuring Multiple Scattering in Step IV: G4MICE Results and Methodologies

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  1. Measuring Multiple Scattering in Step IV Timothy Carlisle Oxford • See MICE Note 374 for updated results

  2. Intro. • Step IV will measure e0in various materials. • G4MICE findse0up to 30% less than predictions: Standard PDG Scattering angle expression: • Potential term actually scales with Z. • Can we use the trackers to measure MS directly?

  3. Scattering Angle comparison Note: DzLiH= 6.3 cm DzLH2 = 57.6 cm

  4. Related studies (1) Cooling Eqn. vs G4MICE G4MICE: Step IV 63mm LiH

  5. Method (1) MICE Note #90 Step IV fields, no Trackers in sim. geometry Start: Matched 2.5mm beam in upstream tracker Simulate in G4MICE • Four runs: • Empty channel & AFC • 35cm LH2& 63mm LiH • Trk. Rec. still in the pipeline. • Apply a smear instead, Gaussian, given: • Trk. Rec. to give 6D particle vectors at Trk. Ref Planes:

  6. Method (2) • Re-simulate in an empty geometry (just fields) • Track downstream beam up to the absorber • Flip momenta • Flip particle sign also • No energy losses • Track upstream beam down through the absorber: Upstream TRP No AFC, no material Downstream TRP Track vectors back to the downstream edge of the absorber position

  7. Method (3) Take vectors at DS edge of Absorber position Calc. angle between them: Plot histogram for all particles. Note: Where: variance = - =+

  8. No AFC (empty geometry) Smear No Smear errors onGeant4 tracking 20 30 40 50 60 70 80 0.02 0.04 0.06 0.08 0.1 0.12

  9. AFC, no Absorber • No Smear • Smear 10 20 30 40 50 60 70 80

  10. AFC + LH2 • No Smear • Smear 10 20 30 40 50 60 70 80

  11. AFC + LiH • No Smear • Smear 10 20 30 40 50 60 70 80

  12. Paraxial beams in G4MICE 35 cm LH2 63 mm LiH

  13. Results (e= 2.5 mm) (e 0 mm)

  14. Summary • PDG ~ 2x more scattering than G4MICE. • Smearing may require further thought re: correlations • LH2 & LiHindistinguishable after smear. • LiHmeasurement < PDG angle. • See MICE Note 374 for updated results

  15. extras

  16. G4MICE output - 35 cm LH2

  17. Related studies (2) From CM28 Step IV: LH2 Step IV: LiH

  18. paraxial beams in G4MICE 35 cm LH2 63 mm LiH

  19. V.L. Highland, Nucl. Instrum. Methods 129, 497 (1975)

  20. AFC + LH2 • No Sear • Smear 10 20 30 40 50 60 70 80

  21. AFC + LiH • No Smear • Smear 10 20 30 40 50 60 70 80

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