work for PID in Novosibirsk E.A.Kravchenko Budker INP, Novosibirsk

E.A.Kravchenko, work for PID in Novosibirsk"2 May 10, 2007 MC simulation of RICH with aerogel and NaF radiators on MCP PMTs  Life-time tests  3 MCP PMTs Status of multilayer aerogel production and characterization Conclusion Outline

E.A.Kravchenko, work for PID in Novosibirsk"3 May 10, 2007 Sodium fluoride radiator Suggested for RICH with a TEA/TMAE pad-photon detector by R. Arnold et al. [ NIM A273 (1988) 466 ] Good transparency in visible & near UV, Almost no light scattering as compared with aerogel, More firm and stable material, though toxic. √2√2 NaF has the lowest refractive index among solids (except aerogel). for λ >170 nm Cherenkov photons refracts out for normal incidence particle, β≈1 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

E.A.Kravchenko, work for PID in Novosibirsk"4 May 10, 2007 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 A.Yu. Barnykov, et al., NIM A553 (2005) 125 A.Yu.Barnyakov, et al., Proceedings of SNIC 2006, eConf C (2006) 0045 FASR-6 gives the best performance at β≈1: Npe = 13, σ β = 5∙10 -4 π/K separation up to 8 GeV/c (better 3σ) 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, work for PID in Novosibirsk"5 May 10, 2007 NaF vs aerogel Normal incidence particles 30 o incidence

E.A.Kravchenko, work for PID in Novosibirsk"6 May 10, 2007 π/K separation 30 o incidencenormal incidence NaF: up to 5 GeV/cNaF: up to 3.5 GeV/c Radiator in the endcap can be tilted so that: | θ i | <20 o

E.A.Kravchenko, work for PID in Novosibirsk"7 May 10, 2007 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 channels, focusing RICH – channels)

E.A.Kravchenko, work for PID in Novosibirsk"8 May 10, 2007 NaF-aerogel multi-ring radiator concept The focusing condition for aerogel is yet to be investigated… FASR NaF

E.A.Kravchenko, work for PID in Novosibirsk"9 May 10, 2007 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, work for PID in Novosibirsk"10 May 10, 2007 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, work for PID in Novosibirsk"11 May 10, 2007 Fast comparison of photocathode aging Photon counting rate sec -1 Duration – 30 minutes Multiplication coefficient Number of tested tubes Average QE degradation at 800nm 'old' PMT with 2 MCPs 1027% 'new' PMT with 3 MCPs % We expect much longer lifetime of ‘new” designed PMTs in real experimental conditions

E.A.Kravchenko, work for PID in Novosibirsk"12 May 10, 2007 Multilayer aerogel production and characterization 100x100x41 mm, Lsc = 45 mm at 400 nm Layernn, (designed) h, mmh, mm (designed) σ (n-1) in the layers ~ 1.5 % - small effect on angle resolution

E.A.Kravchenko, work for PID in Novosibirsk"13 May 10, 2007 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, work for PID in Novosibirsk"14 May 10, 2007 Additional slides

E.A.Kravchenko, work for PID in Novosibirsk"15 May 10, 2007 Monte Carlo simulation (GEANT4) Detector components Geometry 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 QE max =24%  Overall efficiency factor: 50% (packing density & pe collection efficiency)Physics The processes defined: The processes defined:  for charged particles: Cherenkov emission, multiple scattering  for optical photons: Fresnel refraction and reflection, Rayleigh scattering, bulk absorption. Effects considered: Effects considered:  Dispersion of refractive index  Emission point uncertainty  Scattered photons are discarded  Position resolution of photodetector not considered

E.A.Kravchenko, work for PID in Novosibirsk"16 May 10, 2007 Optimization of NaF radiator N pe σθσθ 3.5 GeV/c Thickness 10 mm => 9% X 0 at normal incidence

E.A.Kravchenko, work for PID in Novosibirsk"17 May 10, 2007 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, work for PID in Novosibirsk"18 May 10, 2007 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!