1. 1 st Study of Tracker Misalignments with G4MICE David Forrest University of Glasgow

2. Scope G4MICE Simulations (No digitisation or reconstruction - - yet!) Step VI, 1000 events, 7 beams: 0.5, 1.5, 2.5, 4, 6, 8, 10 pi mm mrad Second tracker only one misaligned ±10 mm, ±3mrad, ±10mm & ±3mrad together, for x and y Partially intended as training exercise

3. Baseline Input Emittance (  mm mrad) Change in Emittance (  mm mrad)

4. 10  mm mrad (translation) Position in MICE (mm) Change in Emittance (  mm mrad) Position in MICE (mm) Change in Emittance (  mm mrad)

5. 10  mm mrad (rotation) Position in MICE (mm) Change in Emittance (  mm mrad) Position in MICE (mm) Change in Emittance (  mm mrad)

6. 10  mm mrad (translation+rotation) Position in MICE (mm) Change in Emittance (  mm mrad) Position in MICE (mm) Change in Emittance (  mm mrad)

7. Effect of Misalignment (translation) on Emittance Input Emittance (  mm mrad) Change in Emittance (  mm mrad) Input Emittance (  mm mrad) Change in Emittance (  mm mrad)

8. Effect of Misalignment (rotation) on Emittance Input Emittance (  mm mrad) Change in Emittance (  mm mrad) Input Emittance (  mm mrad) Change in Emittance (  mm mrad)

9. Effect of Misalignment (translation & rotation) on Emittance Input Emittance (  mm mrad) Change in Emittance (  mm mrad) Input Emittance (  mm mrad) Change in Emittance (  mm mrad)

10. Percentage Changes in emittance due to misalignments for different input beams (pi mm mrad) 0.51.52.546810 X 10mm3.440.210.690.610.111.450.83 3mrad4.151.870.990.220.270.240.10 10mm 3mrad 4.151.450.060.160.280.840.10 Y 10mm0.190.351.532.120.930.400.36 3mrad0.140.190.770.611.220.500.52 10mm 3mrad 4.500.670.690.430.560.741.34

11. Discussion We are clearly dominated by poor statistics. The effect is less than the uncertainty. I don’t yet know how to calculate the error of emittance except for simplistic Poisson argument: 10 3 events -> 3% error. Need to increase number of events: 10 4 events -> 1%; 10 6 events -> 0.1% error Real error should be larger than simple statistics. Is there a G4MICE tool for calculating error in emittance?

12. Discussion We need the alignment to be a negligible error in the total emittance measurement If the goal is to measure emittance with 1% precision then the error in the alignment needs to contribute ~0.1% for it to be negligible. So, goal of alignment study is to achieve 0.1% precision, therefore we should generate 10 6 events per beam → we need the Grid!

13. Future Work Early work, seek to augment through greater attention to: Statistics (GRID) Reconstruction Next steps: Change in B field of spectrometers