1. 11-FEB-2004 TJR1 MICE Beamline TOF Analysis Tom Roberts Illinois Institute of Techology February 11, 2004

2. 11-FEB-2004 TJR2 Question: Do we need tracking in the beamline to improve the TOF1-TOF0 ability to discriminate μ +, π +, and e + ? Answer: No – lack of tracking affects this discrimination less than intrinsic resolutions of the apparatus.

3. 11-FEB-2004 TJR3 Conditions of this Analysis This is the JAN04 beamline design by Kevin Tilley –Diffuser1 is omitted –Diffuser2 is 22.4 mm of Pb (proposal value) For particles with momentum = 240 MeV/c: μ + momentum loss: μ =33 MeV/c, σ = 2.3 MeV/c π + momentum loss: μ =38 MeV/c, σ = 2.2 MeV/c e + momentum loss: μ = 190 MeV/c, σ = 18 MeV/c Only ~1% of the e + get through Diffuser2; very few of those will get through the cooling channel; e + are <1% of particles at TOF0 –Protons are ignored (removed by an upstream Proton Absorber) Generate particles just before Q4 (i.e. after B2) TOF0 is between Q4 and Q5; TOF1 is between Q8 and Q9 Assumed σ TOF0 = σ TOF1 = 50 ps Assumed Tracker1 Momentum resolution < 2.3 MeV/c Decays are disabled (for clarity in the plots)

4. 11-FEB-2004 TJR4 Ideal – Needle Beam Note the highly-relativistic positrons at the bottom.

5. 11-FEB-2004 TJR5 Needle Beam, TOF σ=70ps Due to the nature of eyes and scatter plots, the “thickness” of the lines here appears to be ~ 4-6 σ.

6. 11-FEB-2004 TJR6 Needle Beam σ=70 ps, σ=2.3 MeV/c

7. 11-FEB-2004 TJR7 Comments The previous slide is a model for perfect tracking, using Gaussian smearing to account for our timing and momentum resolution –perfect tracking would account for effects due to path length, so the needle beam is a good model for that Compare to the next slide, which is for particles that fill Q4, the worst case for no tracking, but without timing or momentum resolution –Particles generated flat: -180 ≤ X,Y ≤ 180(radius of Q4 aperture = 178) -0.2 ≤ X’,Y’ ≤ 0.2(length of Q4 iron = 1046)

8. 11-FEB-2004 TJR8 Fill Q4 Clearly the fuzziness from lack of tracking is smaller than our resolutions (which are added to this in the next slide).

9. 11-FEB-2004 TJR9 Fill Q4 σ=70 ps, σ=2.3 MeV/c Compare to the next slide, a repeat of the perfect tracking model and the same resolutions.

10. 11-FEB-2004 TJR10 Needle Beam σ=70 ps, σ=2.3 MeV/c This has more events, because this is 100x faster to track than the previous slide.

11. 11-FEB-2004 TJR11 Conclusion Using a needle beam as a model of having perfect tracking, the lack of tracking affects the TOF1-TOF0 ability to discriminate particles less than either our resolution in time or in momentum (which is dominated by straggling in Diffuser2) The Gaussian resolutions used actually underestimate the real world, especially for momentum