R@D work for PID in Novosibirsk

1. R@D work for PID in Novosibirsk E.A.Kravchenko Budker INP, Novosibirsk

2. Outline • MC simulation of RICH with aerogel and NaF radiators • R@D on MCP PMTs • Life-time tests • 3 MCP PMTs • Status of multilayer aerogel production and characterization • Conclusion E.A.Kravchenko, "R@D work for PID in Novosibirsk"

3. √2 Sodium fluoride radiator Suggested for RICH with a TEA/TMAE pad-photon detector by R. Arnold et al. [ NIM A273 (1988) 466 ] • CAPRICE RICH (balloon-borne, flight in 1994): 10mm thick NaF looked by MWPC with TMAE, pad read-out. • AMS-02 RICH (ISS-borne, tested with beam 2003): 34x34x0.5cm NaF & aerogel n=1.05 looked by MA-PMT array • Good transparency in visible & near UV, • Almost no light scattering as compared with aerogel, • More firm and stable material, though toxic. NaF has the lowest refractive index among solids (except aerogel). for λ >170 nm Cherenkov photons refracts out for normal incidence particle, β≈1 E.A.Kravchenko, "R@D work for PID in Novosibirsk"

4. Aerogel radiators for comparison • SLA 12mm – single layer aerogel with n=1.07 • SLA 24mm – single layer aerogel with n=1.07 • FASR-6 – 6-layer aerogel with single ring • FAMR-3 – 3-layer aerogel with 3 rings FASR-6 gives the best performance at β≈1: Npe = 13, σβ= 5∙10-4 π/K separation up to 8 GeV/c (better 3σ) A.Yu. Barnykov, et al., NIM A553 (2005) 125 A.Yu.Barnyakov, et al., Proceedings of SNIC 2006,eConf C0604032 (2006) 0045 A low momentum solution wanted below aerogel threshold: • Time-of-flight built in aerogel RICH( suggested and tested by Belle RICH group) • Higher refractive index radiator E.A.Kravchenko, "R@D work for PID in Novosibirsk"

5. Normal incidence particles 30o incidence NaF vs aerogel E.A.Kravchenko, "R@D work for PID in Novosibirsk"

6. π/K separation normal incidence 30o incidence NaF: up to 5 GeV/c NaF: up to 3.5 GeV/c Radiator in the endcap can be tilted so that: |θi|<20o E.A.Kravchenko, "R@D work for PID in Novosibirsk"

7. Single photon position resolution NaF is less demanding to pixelization. ~ 4000 channels in the forward RICH For 100 mm expansion gap single layer aerogel RICH needs 100000 channels, focusing RICH – 400000 channels) E.A.Kravchenko, "R@D work for PID in Novosibirsk"

8. NaF-aerogel multi-ring radiator concept FASR NaF The focusing condition for aerogel is yet to be investigated… E.A.Kravchenko, "R@D work for PID in Novosibirsk"

9. R@D on MCP PMTs • Fast degradation of QE was found at long wavelengths • can be used for early detection of ageing • 800 nm – wavelength for comparison of PMT samples after tests E.A.Kravchenko, "R@D work for PID in Novosibirsk"

10. Photocathode ageing of the different design MCP PMTs • Photocathode ageing is rate dependent • Counting rate was increased from test to test keeping the integrated cathode charge constant (~5 nC) • 3 MCP PMTs have the same life time as 2 MCP with protective layer E.A.Kravchenko, "R@D work for PID in Novosibirsk"

11. Fast comparison of photocathode aging • Photon counting rate -109 sec-1 • Duration – 30 minutes • Multiplication coefficient - 106 We expect much longer lifetime of ‘new” designed PMTs in real experimental conditions E.A.Kravchenko, "R@D work for PID in Novosibirsk"

12. Multilayer aerogel production and characterization σ (n-1) in the layers ~ 1.5 % - small effect on angle resolution 100x100x41 mm, Lsc = 45 mm at 400 nm E.A.Kravchenko, "R@D work for PID in Novosibirsk"

13. Conclusion • Use of NaF radiator in the forward RICH looks very promising (PID at low momenta, small number of channels) • Procedure for fast ageing tests of MCP PMTs has been developed • PMTs with 3 MCPs have life time at least as long as 2MCP PMTs with protective layer • Large 3 layers aerogel block has been produced and characterized E.A.Kravchenko, "R@D work for PID in Novosibirsk"

14. Additional slides E.A.Kravchenko, "R@D work for PID in Novosibirsk"

15. Monte Carlo simulation (GEANT4) Physics • The processes defined: • for charged particles: Cherenkov emission, multiple scattering • for optical photons: Fresnel refraction and reflection, Rayleigh scattering, bulk absorption. • Effects considered: • Dispersion of refractive index • Emission point uncertainty • Scattered photons are discarded • Position resolution of photodetector not considered Detector components • Geometry:D = 100 mm - from radiator input face to photodetector plane • Aerogel properties: • Rayleigh scattering length: 5 cm at 400 nm • Aerogel bulk absorption length: 400cm at 400 nm • Photodetector: • Bialkali photocathode with borosilicate window QEmax=24% • Overall efficiency factor: 50%(packing density & pe collection efficiency) E.A.Kravchenko, "R@D work for PID in Novosibirsk"

16. kaons @ 3.5 GeV/c σθ Npe Optimization of NaF radiator Thickness 10 mm=> 9% X0at normal incidence E.A.Kravchenko, "R@D work for PID in Novosibirsk"

17. Technical requirements on multilayer aerogel, single ring (index of refraction) Accuracy on the refractive index in the layers • 6-layer option • 2 cases – • “correlated” (all layers change equally) • “anti-correlated” (half of the layers increase, other decrease) E.A.Kravchenko, "R@D work for PID in Novosibirsk"

18. Technical requirements on multilayer aerogel, single ring (longitudinal density variations) Accuracy on the density variations along the track • case sensitive • negative – variation in the layer from low values to high (continuous focusing) • positive – variation from high values to low Technical requirements on multi ring aerogel are more simple! E.A.Kravchenko, "R@D work for PID in Novosibirsk"