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!