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R@D work for PID in Novosibirsk
E.A.Kravchenko
Budker INP, Novosibirsk
E.A.Kravchenko, "R@D work for PID in Novosibirsk"
2May 10, 2007
MC simulation of RICH with aerogel and NaF radiators
R@D on MCP PMTsLife-time tests3 MCP PMTs
Status of multilayer aerogel production and characterization
Conclusion
Outline
E.A.Kravchenko, "R@D work for PID in Novosibirsk"
3May 10, 2007
Sodium fluoride radiatorSodium fluoride radiatorSuggested for RICH with a TEA/TMAE pad-photon detector byR. 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
NaF has the lowest refractive index among solids (except aerogel).
2n for λ >170 nmCherenkov 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, "R@D work for PID in Novosibirsk"
4May 10, 2007
Aerogel radiators for comparisonAerogel 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) 125A.Yu.Barnyakov, et al., Proceedings of SNIC 2006, eConf C0604032 (2006) 0045
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 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"
5May 10, 2007
NaF vs aerogelNaF vs aerogel
Normal incidence particles
30o incidence
E.A.Kravchenko, "R@D work for PID in Novosibirsk"
6May 10, 2007
π/K separationπ/K separation30o incidencenormal 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"
7May 10, 2007
Single photon position resolutionSingle 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"
8May 10, 2007
NaF-aerogel multi-ring radiator conceptNaF-aerogel multi-ring radiator concept
The focusing condition for aerogel is yet to be investigated…
FASRFASR NaFNaF
E.A.Kravchenko, "R@D work for PID in Novosibirsk"
9May 10, 2007
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"
10May 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, "R@D work for PID in Novosibirsk"
11May 10, 2007
Fast comparison of photocathode aging
Photon counting rate -109 sec-1
Duration – 30 minutes Multiplication
coefficient - 106
Number of tested tubes
Average QE degradation at 800nm
'old' PMT with
2 MCPs 10 27%
'new' PMT with 3 MCPs 17 1.3%
We expect much longer lifetime of ‘new” designed PMTs in real experimental conditions
E.A.Kravchenko, "R@D work for PID in Novosibirsk"
12May 10, 2007
Multilayer aerogel production and characterization
100x100x41 mm, Lsc = 45 mm at 400 nm
Layer n n, (designed)
h, mm h, mm (designed)
1 1.046 1.050 12.6 12.5
2 1.041 1.044 13.2 13.3
3 1.037 1.039 15.2 14.2
σ (n-1) in the layers ~ 1.5 % - small effect on angle resolution
E.A.Kravchenko, "R@D work for PID in Novosibirsk"
13May 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, "R@D work for PID in Novosibirsk"
14May 10, 2007
Additional slides
E.A.Kravchenko, "R@D work for PID in Novosibirsk"
15May 10, 2007
Monte Carlo simulation (GEANT4)Monte Carlo simulation (GEANT4)
Detector componentsDetector components GeometryGeometry:D = 100 mm - from radiator input face to photodetector plane Aerogel properties:Aerogel properties:
Rayleigh scattering length: 5 cm at 400 nm Aerogel bulk absorption length: 400cm at 400 nm
Photodetector:Photodetector: Bialkali photocathode with borosilicate window QEmax=24% Overall efficiency factor: 50%(packing density & pe collection efficiency)
PhysicsPhysicsThe 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 indexEmission point uncertaintyScattered photons are discardedPosition resolution of photodetector not considered
E.A.Kravchenko, "R@D work for PID in Novosibirsk"
16May 10, 2007
Optimization of NaF radiatorOptimization of NaF radiator
Npe
σθ
kaons @ 3.5 GeV/c
Thickness 10 mm =>9% X0 at normal incidence
kttN
2
ch
pe
2ep
2ch
tNt pe ,ep
E.A.Kravchenko, "R@D work for PID in Novosibirsk"
17May 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, "R@D work for PID in Novosibirsk"
18May 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!