1. Improved Cherenkov Threshold detectors for heavy-ions experiment P. Martinengo,CERN – High-pT Physics at LHC,Tokaj’08

2. Can we extend the ALICE PID for hadrons above 5 GeV/c ? ALICE Club - May 2, 2005 Paolo Martinengo

3. What means “high-pT“ ?

4. HMPID TDR U. Wiedemann, Heavy Ions Forum, 10 February 2004 HMPID 3σ p/K limit

5. HMPID TDR yesterday HMPID 3σ p/K limit

6. HMPID TDR yesterday start of LHC HMPID 3σ p/K limit

7. HMPID TDR yesterday start of LHC first HI collision ? HMPID 3σ p/K limit

8. Conclusion The HMPID is an excellent detector with a wrong name !

9. Identify hadrons with p T ≥ 10 GeV/c track-by-track Inclusive measurement, particle yields, especially protons Weak identification, i.e. Π,K – protons can be enough Home work

10. Material nΠ thr (GeV/c)K thr (GeV/c)P thr (GeV/c) θ max (β=1) Diamond 2.417 0.06 0.25 0.42 65 o Plexiglas 1.488 0.13 0.45 0.85 48 o Vodka 1.363 0.15 0.53 1.01 43 o Beer 1.345 0.15 0.54 1.03 42 o Water 1.332 0.16 0.56 1.07 41 o C 6 F 14 1.29 0.17 0.60 1.13 39 o CF 4 (liquid) 1.226 0.19 0.7 1.32 35 o Aerogel1.05-1.01 0.4-1 1.5-3.5 3-718 o – 8 o C 4 F 10 1.00140 2.6 9 17 3 o Isobutane 1.00127 3 10 18 2.9 o Argon 1.00059 4 14 27 2 o CF 4 (gas) 1.00050 5 16 30 1.8 o Methane 1.00051 5 16 30 1.8 o Air 1.00029 6 20 39 1.4 o Helium1.000033 17 60 115 0.5 o N γ (cm -1 eV -1 ) ~ sin 2 θ (HMPID 1.5 cm liquid C 6 F 14 )

11. ~ 2m

12. LHCB RICH1 2.4 m LHCB RICH2 2.0 m BTeV RICH2 3.0 m COMPASS > 3.0 m CBM ~2.5 m All fixed-target !

13. “ The examples set forth show the great importance which the radiation caused by particles moving at a speed greater than that of light has acquired in experimental physics. Even so, we have not by a long way exhausted all the possibilities for their practical use. There can be no doubt that the usefulness of this radiation will in the future be rapidly extended.” End of Čerenkov’s Nobel lecture (1958)

14. ITC I mproved T hreshold C herenkov or TIC T hreshold I maging C herenkov ?

17. Nice detector but the radiator is too long ( 1m for γ ’s )

18. The γ ’s yield is too low but compact, simple layout well known and mastered technology θ c is not measured but γ ’s are associated to tracks  robust w.r.t. high multiplicity, noise Is it possible to improve the γ ’s yield ?

19. Yes, it is C 4 F 10 CaF 2 IP HMPID CsI photo-cathode

20. Quartz cut-off

21. The HADES RICH HMPID’s brother, both sons of RD26

23. 1.5 m

24. Radiator thickness 36 to 65 cm, 12 to 22 γ ’s

25. MomentumDetector resp.Particle id. < 3 GeV 0Who cares? 3 < p < 9 1 Π 0 K,p 9 < p < 17 1 Π,K 0 p > 17 GeV 1Who knows ? C 4 F 10 radiator

26. Can we do better ?

27. Yes, we can CF 4 Window less !

28. CF 4 + CsI give 40 γ ’s with 50 cm radiator !

29. CF 4 transparent down to 110 nm !

31. Why not a GEM detector ? (perhaps with the ALTRO R/O) Nucl. Instrum. Methods Phys. Res., A 535 (2004) 324-329 Nucl. Instrum. Methods Phys. Res., A 523 (2004) 345-354

32. MomentumDetector resp.Particle id. < 5 GeV 0Who cares? 5 < p < 16 1 Π 0 K,p 16 < p < 30 1 Π,K 0 p > 30 GeV 1Who knows ? CF 4 radiator

33. Interesting but not exactly what we want …

34. DOUBLE RADIATOR TIC CaF 2 window C 4 F 10 CF 4 Window less !

35. Momentum C 4 F 10 CF 4 Particle id. < 3 GeV 0 0Who cares? 3 < p < 5 1 0 Π 5 < p < 9 1 1 Π 9 < p < 16 1 1 Π 1 0 K 0 0 p 16 < p < 30 1 1 Π,K 1 0 p > 30 GeV 1 1Who knows? C 4 F 10 + CF 4 radiators But Čerenkov angles are very similar ! ( 3 o and 1.8 o )

36. CF 4 C 4 F 10 This would work but it is not elegant

37. DOUBLE RADIATOR TIC CaF 2 window C 4 F 10 CF 4 Window less !

38. C 4 F 10 CF 4 ~2.5 cm ~ 10 cm 50 cm + 50 cm ~3 cm

40. First results from “test beam” C 4 F 10 C 4 F 10 + CF 4 50 cm + 50 cm # of photonsTotal charge

41. Single radiator TIC C 4 F 10 CaF 2 IP HMPID CsI photo-cathode

42. SIMULATION Cherenkov photons Mirror chamber (Giacomo Volpe)

43. 3 GeV/c pions, 189 charged pads 5 GeV/c pions, 366 charged pads 10 GeV/c pions, 564 charged pads SIMULATION

44. Blob diameter for C 4 F 10, pad size = 0.8x0.8 cm 2

45. Nikolai Smirnov, Yale Univeristy Y Z X 50 cm AeroGel, 10cm UV Mirror, spherical shape in ZY Double sided Read-out plane Triple GEM foils with CsI CaF2 Window C4F10 gas CF4 gas Particle track & UV photons R position: 500 cm. Bz: 0.5 T More ideas…

46. Simulation for high Pt π + R Z Flat mirror Spherical mirror In saturation:  25. (C4F10); 30. (CF4) Double sided Read-out plane Triple GEM foils with CsI CaF2 Window UV Mirror, spherical shape in ZY AeroGel, 10cm C4F10 gas CF4 gas

49. Thick GEM with resistive electrodes (RETGEM)- a fully spark protected detector A. Di Mauro et al, Presented at the Vienna Conf. on Instrum; to be published in NIM Geometrical and electrical characteristics: Holes diameter 0.3-0.8 mm, pitch 0.7-1.2 mm, thickness 0.5-2 mm. Resitivity:200-800kΩ/□ Kapton type: 100XC10E 30mm or 70mm Principle of operation

50. Filled symbols-single RETGEM, open symbols –double RETGEMs Stars-gain measurements with double RETGEM coated with CsI layer. 15 min continues discharge QE~30% at λ=120nm Energy resolution ~30%FWHM for 6 keV With increase of the rate the amplitude drop, but now discharges Summary of the main results obtained with kapton RETGEMs 1 mm thick Fully spark -protectedFully spark -protected Discovery: kapton can be coated with CsI and have after high QE

51. Thick GEMs work even with “unconventional” gas mixtures, i.e. pure Neon or Argon and even in dry air ! (Vladimir Peskov + Budapest group)

52. Anything wrong with dry air? Cheap ! Abundant ! Non flammable ! ~Correct refractive index ! Eigenshaften der Materie in Ihren Aggregatzustanden, 8. Teil Opische Konstanten, 1962 + 18 ppm Ne, 5.2 He, 1.5 CH 4, 1.14 Kr, 0.5 N 2 O, 0.5 H 2, 0.4 O 3, 0.086 Xe From Olaf Ullaland’s presentation at the CBM workshop

53. With a little bit of mixing of CF 4 and Ne : Setting (n-1)  10 6 = 350 at 400 nm gives a mixing ratio of CF 4 :Ne = 67:33 Well described by: at 0 o C and 760 torr ‘The Dutch Chemist’, c 1780s. Copper engraving by J Boydell after a painting by J Stein.

54. It may work !

55. Conclusions (2) It is possible to extend the PID capability of ALICE up to 30 GeV/c making use of presently available technologies at reasonable cost in a reasonable time But it is useless if we don’t find a trigger !

56. (Olav Ullaland)