TOF0

1. PARTICLE ID - CKOV1 STATUS REPORT UM/UCL ISIS Beam Iron Shield TOF0 TOF1 Diffuser Iron Shield TOF2 Ckov2Cal Proton Absorber Ckov1 L. Cremaldi, G. Gregoire, D. Summers CKOV1 p/m = 1/1000 => 3.5-4.0s Acive aperature +-25cm Low energy MICE, 250-300MeV/c MICE Capable of measuring beamline purity. Device should exceed >4.0 s ?? • LN2 Option • RICH Option • LH Option MICE COLLABORATION MEETING, RAL OCT2005

2. Beam Profiles at CKOV1 (dated) UM/UCL Accepted muons r=10cm r=23cm Accepted muons r=23cm

3. Low Index Radiators UM/UCL

4. LN2 Radiator for High Momentum UM/UCL Photo-Electrons Cerenkov Angle     • 240-300 MeV/c • About ~100 pe x 2/3 light collection efficiency ~ 65 pes. • Light Collection Uniformity issues !! • About 4 - 7 degrees of angular separation. Not Used (Ghislain, RICH )

5. Benchmarck Design for TDR UM 240 MeV/c 10 cm LN2 280 MeV/c 10 cm LN2 pions pions muons muons 4.0 2.5 98 66 38 82 • 4-MIRROR/PMT DESIGN • r = 23 cm active aperature • FC72 Radiator 150-200 MeV/c Z = 5cm • LN2 Radiator 240-300 MeV/c Z = 10cm Light Box • Light Collection Uniformity needed to be studied. Radiator Vessel

6. Ray Tracing UM • Collection Efficiency can vary significantly over the aperature for pi and mu. Mu 250MeV/c 10cm LN2 (x,y)= (0, 0) cm eff=71/89 Mu 250MeV/c 10cm LN2 (x,y)= (0, -5) cm eff=42/89

7. Light Collection Scan 4 Mirror/PMT UM 250MeV/c 10cm LN2 Npe y=scan x=0cm muons pions y-cm • Mu /Pi separation very problematic at first look. • Optimization leads difficult. • Add PMT/Mirror (s)

8. Light Collection Scan 8 Mirror/PMT UM Outer Track Outer Track Inner Track Inner Track Outer Track Outer Track • PID quite ambiguous--> Central pion looks like Wing muon. • (x,y) position should be known for more robust PID Algorithm. • PID separation varies between 3.2 <--> 2.2 w (x,y) Npe 250MeV/c 10cm LN2 10cm LN2 300MeV/c y=scan x=0cm y=scan x=0cm ~2.2 ~3.2 y-cm y-cm

9. Light Collection Scan 12 Mirror/PMT UM 250MeV/c 10cm LN2 300MeV/c 10cm LN2 y=scan x=0cm y=scan x=0cm ~3.2 ~2.3 Outer Track Outer Track Inner Track Inner Track Outer Track Outer Track y-cm y-cm • 12 PMT/Mirror design with r=5cm central trigger scintillator leads to • 2-3 s separation. • Trigger counter to define Inner and Outer Tracks. Npe

10. LN2 Summary UM Light box Radiator Trigger cnt • LN2 + 4- mirror/pmt design difficult to optimize. • LN2 +8/12 mirror/pmt model looks more promising. • Central trigger counter should be used to define • Inner and Outer tracks for PID algorithm. • 4s separation difficult/miracle over full 240-300 MeV/c.

11. TOFC Concept UM 23cm 10cm PMT PMT 18o 26o LN2 Top view muon pion 75cm --> (3.0+-0.2)ns +-0.2ns slewing 50cm --> (2.0 +- 0.2) ns +- 0.2ns slewing  burst 450ps mu 26o -> 0.450rd --> 4.5 cm/bounce --> 4-5 bounces  = 0.94.5 = 62% pi 18o -> 0.310rd --> 3.1 cm/bounce --> 7-8 bounces  = 0.97.5 = 45% Timimg off leading 1-2 pe??

12. Timing&Pulse Height Simulation UM 240MeV/c 260MeV/c 280MeV/c 300MeV/c • Pion signals arrive later and • straggle in. • Simulations suggest that with • t~ 250ps resolution one might • resolve the mu-pi . • 2” pmts needed to collect light. • Photonis XP2020 • Hamamatsu 5320 0 25ns 0 25ns

13. Pattern Recognition with 12 PMTs UM X=0. Y=0. cm X=20. Y=0. cm PMT # mu pi Time (ns) X=5. Y=5. cm X=10. Y=10. cm

14. RICH Option - G. Gregoire UCL Plane mirror Sample size: Simple geometry 50 k pions 585 mm 50 k muons 50 k electrons Diam. 250 mm ( Colors correspond to different particle species ) 350 mm 20-mm thick radiator Y Pixel size = 2 x 2 mm2 Electrons Muons 1200 mm X Pions 5 1200 mm

15. Radiator Thickness - G. Gregoire UCL • Shifts due to refraction in the thicker radiator m p e (at the expense of light output) sR 3 mm Conclusions • At 280 MeV/c the thickness of the radiator has not much influence on imaging • Large detecting plane due to plane mirror Optical focusing needed  100% light collection efficiency mandatory 7

16. Focusing - G. Gregoire UCL Non exhaustive ! Very preliminary ! Not optimized Goal: Č light produced at the focus to get a parallel beam after reflection and placing the detecting plane perpendicularly (for easy simulation/reconstruction)  400 mm 1200 mm 1200 mm Spherical mirror Parabolic mirror Spheroidal mirror R=-1100 mm Rcurv=-1500 mm Rcurv= -600 mm along X Plane mirror e = 0 e = -1 Rcurv=-1100 mm along Y More x-focusing obviously needed ! 8

17. Full Beam - G. Gregoire UCL Muons only 190 MeV/c 280 MeV/c Biconic mirror ( not optimized ) Losses < 5 10-4 700 mm 700 mm Faint ring due to aberrations … 700 mm 700 mm Pixel size 1 mm x 1 mm • The detecting plane does not have to be sensitive over the full area • For all muon momenta covered by MICE, 135 < Radius of Č rings < 275 mm For all impact positions and directions at the radiator

18. Detection Plane - G. Gregoire Just an Example, Not a proposal. Imagine the detection plane is equiped with multianode PMTs like Hamamatsu H7600. Annular Coverage 270 mm < D < 550 mm H7600 Square PM 26 x 26 mm 16 pixels 4 x 4 mm each Gain 3.5 106 12 stages bialkali 300 < l < 600 nm 6

19. Detected Photons from muons - G. Gregoire UCL For Cherenkov rings, originating from muons hitting any position on the radiator Nr of photons reaching the detection plane = 89 Average nr of anodes hits = 79 assuming 100% light collection efficiency (for muons of 280 MeV/c) Geometrical efficiency =89 % 7

20. Rings - G. Gregoire UCL Px = 45.29 MeV/c Py = 80.42 MeV/c Pz = 166.08 MeV/c X =-89.88 mm ; y = 35.42 mm Y X Elementary PID algorithm • Origin = barycenter of the hits • Average distances to the center Separation at 3-s level … without any optimization of the optics ! 10

21. LH Option Revisited - D. Summers UM LH n=1.112 (100cm)

22. Liquid Nitrogen Cerenkov at Brookhaven UM Phys. Rev. Lett. 4 (1960) 242"In the energy range in which protons of the same momentum had a velocity less than 0.8c, a liquid nitrogen Cerenkov counter was used in place of the gas counter.” Phys. Rev. 125 (1962) 690"For measurement of the pi+ cross section from 450 MeV thru675 MeV, a liquid-nitrogen Cerenkov counter was substitutedfor the gas counter. The index of refraction of liquidnitrogen (n = 1.2053 at its boiling point) was adequate toseparate pions from protons in this energy range.” Tom Devlin Thesis "The counter was constructed quite simply by putting a 6810A phototube with a light tight sealon the neck of a nitrogen dewar. The phototubewas easily removed for checking the level ofnitrogen and filling the Dewar. Although thenitrogen level was kept low enough so that itnever came in physical contact with the phototube,the tube was maintained at very low temperature. This had the desirable effect of a low noise levelin its output. Qualitative checks on the countershowed it to be nearly 100% efficient. Since any inefficiency would have no effect on the cross section, no attempt was made to determine it exactly."

23. LH Vessel UM pmt 5” pmt vacuum Jacket/ super insulation 50cm 50cm liner 40cm 50cm LH 20oK • LH Dewar (20degK) • Lined or Painted with Diffuse Reflector • Vaccuum or Foam Insulation?? • ~ 33% Light Collection Efficiency ~ 40 Pe fill tank Quartz vacuum Window + N2 flush • Concerns • H poisoning • H Scintillation

25. Test Beam PSI/CERN/FNAL/KEK UM/UCL • Test beam with LN2 radiatior. • Basic light collection and uniformity scans can be measured. • Test light collection with pipe. • Number of PMTs (1-3) • Scale to LH Pmt(s) Light pipe liner LN2 77oK

26. SUMMARY • UM/UCL team - good synergy. Others welcomed. • LN2 Option intrinsically incompatible with (3.5-4.0)s separation • for high energy MICE. • RICH Option very powerful. Detection plane expensive? PMTs, • GEM, MSGC, PWC. Additional manpower needed for RICH • development. • LH Option intrinsically sound ON-OFF type device. • LH vessel/optics presents a challeng with safety issues. • Lab assistance and cryo-engineer probably needed. • Test Beam in ‘06’