aerogel radiator
DESCRIPTION
4 separation confirmed. Cherenkov photon. “K”4.0GeV. 4.0GeV. Aerogel radiator. n=1.05. Position sensitive PD with B=1.5Tesla. 200mm. R&D project since 2000. Crack-free large sample has been made. refractive index control. n =1.050. n = 0.0003. index deviation from average. - PowerPoint PPT PresentationTRANSCRIPT
A Study of Proximity Focusing RICH A Study of Proximity Focusing RICH with Multiple Refractive Index Aerogel Radiatorwith Multiple Refractive Index Aerogel Radiator
1I. Adachi, 2I. Bertović, 3K.Fujita, 4T. Fukushima, 2A. Gorišek, 3D. Hayashi, 3T. Iijima, 3K.Ikado, 5M.Iwabuchi, 4H. Kawai, 6,2S. Korpar, 3Y. Kozakai, 7,2P. Križan, 4A. Kuratani, 8T. Matsumoto, 3Y. Mazuka, 8T. Nakagawa,
1S. Nishida, 5S. Ogawa, 2R. Pestotnik, 8T. Seki, 8T. Sumiyoshi, 4M. Tabata, 1Y. Unno
1:IPNS, KEK, Tsukuba, Japan / 2:J.Stefan Institute, Ljubljana, Slovenia / 3:Dept. of Physics, Nagoya Univ., Nagoya, Japan / 4:Dept. of Physics, Chiba Univ., Chiba, Japan /5:Dept. of Physics, Toho Univ., Funabashi, Japan
6:Faculty of Chemistry and Chemical Engineering, Univ. of Maribor, Maribor, Slovenia 7:Faculty of Mathematics and Physics, Univ. of Ljubljana, Ljubljana, Slovenia / 8:Dept. of Physics, Tokyo Metropolitan Univ., Tokyo, Japan
presented by Peter Križan ([email protected])
Aerogel radiator
Position sensitive PDwith B=1.5Tesla
Cherenkov photon
200mm
n=1.05
Proximity Focusing RICH with Aerogel Radiator
Developed for a new particle ID device in the Belle forward region• improve /K separation up to 4 at 4 GeV/c• limited space• operational under 1.5 Tesla magnetic field
Key components• Hydrophobic aerogel with refractive index of ~1.050 as a Cherenkov radiator• Position sensitive photodetector with ~5x5mm2 pixel size• Electronics for read-out
Belle detector
Performance Test at 2002 Beam Experiment
n=1.05 aerogel radiator
=14mrad Npe = 6 4 separation confirmed
4.0GeV“K”4.0GeV
typical event
RICH prototype counter
Hamamatsu Multi-anode Flat-Panel PMT(H8500)
/K 4 separation at 4 GeV/c achieved with a prototype counterneed more photoelectrons for a further improvement as well asfor more robustness HOW ?
R&D project since 2000
Innovative idea to Get More Photoelectrons w/o Degrading Resolution
Simple accumulation of aerogel layers allows to detect more Cherenkov photons, however it deteriorates overall resolution.
n1 n2
n1<n2
Employ multiple layers with different indices so that Cherenkov images from individual layers overlap on the photon detector.
Concept Validation in Beam
4cm-thick single index aerogel
(1p.e.) = 22 mrad Npe ~ 10.6
(track) = 6.9 mrad
Focusing by 2cm+2cm aerogel (n1:1.047, n2:1.057)
n1 n2 (1p.e.) = 14.4 mradNpe ~ 9.6
(track) = 4.8 mrad
Novel idea of dual radiator “focusing scheme” has been proven Only possible because refractive index of aerogel radiator can be adjusted in the production Require further improvement of aerogel transparency not only for n=1.050 but for other indices
Progress in Aerogel Radiator Production
Measured index
Tra
nsm
issi
on le
ngth
at
400n
m(m
m)
old synthesis method
Transparency improvement for samples with n=1.040~1.060
Crack-free large sample has been made
110x110x20mm3 150x150x20mm3
n =1.050
refractive index control
n = 0.0003
index deviation from average
Extension of the new concept: multiple layer radiator
High accuracy of index is advantageous for dual/multiple layer radiator configurations
2001 sample
Target indexAveraged transmission
length at 400nm
1.045 46.6 1.4
1.050 40.4 1.1
1.055 32.8 1.1
1.060 28.9 0.7
1.0451.050
1.0551.062
# of photoelectrons
▲: single index layer
●:multiple layer
1st 2nd 3rd4th
1st
2nd
3rd
4th
▲: single index layer
●:multiple layer
With new aerogels provided, we have examined the performance by stacking more layers during a 2005 beam test
single photon resolution
Comparison between single index and multiple radiator schemes(3.0 GeV/c pion beam) resolution per track
best (track) = 4.2 mrad
We have succeeded in getting more Npe without an increase in the single photon uncertainty.
Single index radiator n = 1.045 only
Multiple layer radiator
n1 = 1.045
n2 = 1.050
n3 = 1.055
n4 = 1.062
|()-()|/(track) ~5.5separation achieved for 4 GeV/c with Npe= 9.1 Progress on aerogel optical quality has b
een examined in test beam
radiator thickness(cm)
Npe
2001 sample
2005 sample
Significant increase of Npe observed for 2005 sample, while old sample gets saturated around Npe~4.5
Transmission length at = 400nm more than doubled
10mV
Conclusions
1. In 2004 we have introduced and tested a new technique which uses multiple aerogel tiles with different indices so that Cherenkov photons can be imaged to overlapping rings. With this configuration, we have demonstrated a 5.5 separation with ~9 photoelectrons in the 2005 beam test.
2. Optical quality of aerogel tiles has been significantly improved. As a result, photoelectron yield has been doubled. The radiator size can be enlarged by 86% and crack free sample was obtained.
3. We have tested additional time-of-flight capabilities of such a counter. Both Cherenkov photons from the aerogel radiator as well as from the PMT window can be used. The latter would allow to extend the PID capabilities of the counter to particles which are below the Cherenkov threshold in aerogel. References
1. T.Iijima et al., NIM A543(2001)321.2. T.Matsumoto, S.Korpar et al., NIM A521(2004)367.3. T.Iijima, S.Korpar et al., NIM A548(2005)383.4. I.Adachi et al., NIM A553(2005)146.5. P.Križan et al., physics/0603022, to be published in NIM A.
Additional feature: RICH+TOF
Idea: Make use of the fast photon detectors and measure time-of-flight with Cherenkov photons from aerogel and from the PMT window
The Cherenkov photons from the window: can be used for particles below the threshold in aerogel
The separation in Belle should be even better: flight distance ~2m (instead of 0.7m in the beam test set-up).
Beam test data:
50ps resolution per single photon ~20ps per track
~38ps per track
Separation of pions and protons at 2 GeV, flight distance 0.7m.