1. CKOV1 design status 1. Generation of muon and pion beam files 2. PID performances with water radiator 3. Does it help with fluorocarbon FC72 ? 4. Conclusion December 2, 2005 Gh. Grégoire Contents

2. DISC geometry Detecting plane 20-mm thick radiator Diam. 300 mm Front plate = 1 mm Al Back window = 3 mm quartz Curved mirror surface 500 mm 2 2 muons in red 2 pions in blue Same geometry as presented on Nov. 16 (PC-152)

3. Radiator vessel 1 mm Al plate Radiator medium (water or FC72) 3-mm quartz exit window 2 muons in red 2 pions in blue 3 Details of refraction due to quartz window

4. Simulations Radiator20-mm thick ParticlesMuons (10 kevts) in liquid radiator and FC72 Diameter = 300 mm 4 (to match Tom’s recent beam design) Water and FC72 No reaction or beam files from T. Roberts … Generation of beam files reproducing the latest beam design with 6  emittance (obtained from partial plots at TOF0 shown during CM-13 in RAL) Transverse distributions from plots shown at RAL Momentum distribution from Lucien’s talk during PC-152 (Nov. 16, 2005) Angular distributions: gaussian with  = 25 mrad (S. Kahn, March 31, 2005) Muons (10 kevts) in 3-mm quartz window Average p  = 230 MeV/c  p/p ~ 8 % Pions (10 kevts) with the same distributions and impact points as muons

5. Transverse distributions 5

6. Angle and momentum distributions Average momentum ~ 230 MeV/c  p/p ~8 %  = 25 mrad 6

7. Cherenkov photons Radiator 20 mm230 MeV/c Water FC72 Overlap ! 7

8. Correlations Expected overlap since both light yield and Cherenkov angle depend on the same  8 Similar to Lucien’s plot « radius vs momentum » (transp. 5 for PC-152) and same conclusions (contour cut). Muons Pions Muons Pions Muons Pions Light yield vs momentum. p obtained from Tracker !

9. Results Muons Pions 600 mm X Y Cut through y-axis Water radiator Photoelectrons in detection plane 10 4 muons and 10 4 pions 9

10. Quartz window Liquid medium 10 4 photons emitted in the window 1.6 % of the photons emitted in the window reach the detector plane (picture shown for 10 4 muons traversing the window ~ 7 10 5 p.e.) 10

11. Contribution of window Muons Pions Photons generated in the quartz window 11 Negligible!

12. FC72 Muons Pions 600 mm X Y Cut through y-axis Photoelectrons in detection plane 10 4 muons and 10 4 pions Smaller radii and less photons ! Slightly better separation but still unacceptable overlap ! 12

13. Conclusion If MICE is working with a large  p/p (typ. 8 %), there is no useful pion-muon separation in the detection plane at 230 MeV/c (and it gets worse at higher momenta) 13 I do not see why we should built CKOV1 as it would be of no additional help … the (simultaneous) measurement of the light yield in the PMTs does not help as there is also an overlap between pions and muons (see transp. 8) If, in addition, the pion/muon ratio is so small (and if we believe it) For the available radiator media, Let’s hope that the tracker and TOF together reach an acceptable separation even at the highest momenta. If they fail and if the pion contamination is significant, then the momentum byte should strongly reduced (to the 1% level) to benefit from a CKOV1