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Highlights from RICH2007. PPD Seminar. S.Easo, A.Papanestis, S.Ricciardi. Contribution from S.Easo. 28-11-2007. Outline. RICH detectors in accelerator based experiments:. Review of Advantages and Limitations of RICH for PID. R&D for new RICH systems.

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Highlights from RICH2007

PPD Seminar

S.Easo, A.Papanestis, S.Ricciardi

Contribution from S.Easo



  • RICH detectors in accelerator based experiments:

  • Review of Advantages and Limitations of RICH for PID

  • R&D for new RICH systems

  • Historical Overview: 1900 (Marie & Pierre Curie)

    1934-44 P.Cherenkov + Frank + Tamm

    1960 Arthur Roberts : First Proposal for RICH

    1976 T. Ypsilantis + J. Seguinot :

    Pioneering the construction of the first RICH

RICH design: Basics

For momenta well above threshold

p/K separation-limiting case

Refractive Indices

n=1.474 (Fused Silica)

n=1.27 (C6F14 CRID)

n=1.02 (Typical Silica Aerogel)

n=1.001665 (C5F12/N2 CRID Mix)

n=1.0000349 (He)





2 mrad

1 mrad

0.5 mrad

0.1 mrad

  • N s optimization is not the whole story: One needs to minimize the misID rate

    and maximize the Positive ID efficiency.

  • Sources of misID includes interactions, particle decays, physics effects

    in other parts of the detector etc.


Detectors photon detection and radiator thresholds
Detectors-Photon Detection and Radiator Thresholds

  • Aerogel: Rayleigh scattering  Low effective transmission at low wavelengths


Rich imaging limits to performance
RICH Imaging-Limits to Performance

  • N pe : More Photons are better, but limited by the technology available.

  • Larger bandwidth rapid increase in chromatic error

  • C : Need excellent tracking detector and control of alignment systematics

  • Physics Limits: overall performance for the event limited by decays and interactions.

  • Single photon resolution:


  • Examples of performances shown in the following slides.

  • Many choices available for tuning the performance.



LHCb-RICH three radiators: Aerogel, C4F10 and CF4.

  • Pioneered the use of HPDs: 1024 pixels per tube bump bonded to readout chip and

    encapsulated in the vacuum tube.


  • RICH2 installed and ready for global commissioning.

  • RICH1: Major parts installed. Photodetectors ready to mount on RICH1.

Example of LHCb-RICH PERFORMANCE three radiators: Aerogel, C4F10 and CF4.

  • Performance as seen in Simulated Data in 2006

  • Yield: Mean Number of hits per isolated

  • saturated track (Beta ~1).

Single Photon Cherenkov Angle Resolutions in mrad.

  • Chromatic: From the variation in

  • refractive index.

  • Emission Point: Essentially from the

  • tilt of the mirrors.

  • Pixel Size: From the granularity of the

  • Silicon detector pixels in HPD

  • PSF ( Point Spread Function):

  • From the spread of the Photoelectron direction

  • as it travels inside the HPD

LHCb RICH three radiators: Aerogel, C4F10 and CF4.

LHCb RICH PID Performance

B0sDs-K+B0sDs- p+


After using RICH, background at 10% level from 10 times level

BABAR three radiators: Aerogel, C4F10 and CF4.DIRC: PERFORMANCE

  • DIRC measures

J. Schwiening

  • DIRC Performs as per design: p/K separation in 0.54 GeV/c

DIRC Upgrade: Focusing DIRC for Super B Factory three radiators: Aerogel, C4F10 and CF4.

  • Prototype tests made with 6 X 6 mm Hamamatsu H8500 flat panel MAPMT (sTTS=140 ps),

    Burle 85011 MCP-PMT( sTTS = 50-70 ps),

    3 X 12 mm Hamamatsu H9500 Flat panel PMT ( s TTS =220ps).

J. Schwiening

DIRC Upgrade: Expected Performance three radiators: Aerogel, C4F10 and CF4.


Lpath=10 m

Npe = 28 for 1.7 cm quartz


J. Schwiening

BELLE Upgrade: Super B Factory three radiators: Aerogel, C4F10 and CF4.


  • Beam Tests done with 2cm thick Aerogel tiles and H-8500 Flat panel MAPMT:

  • Details in NIMA 553 (2005) 58

  • Single photon resolution: 15 mrad, Npe = 6. This yields a 4 s K/p separation

  • The photon detector does not work in Magnetic field

BELLE Upgrade: Proximity Focusing RICH three radiators: Aerogel, C4F10 and CF4.

T.Iijima, P.Krizan

  • Other Photon detector options for 1.5 T field:

  • To increase the yield: increase the thickness of aerogel or use aerogel tiles as multiple radiators.



4cm thick aerogel



Multiple Radiators

2 layers of 2cm thick

n1=1.047, n2=1.057

p/K separation with focusing configuration ~ 4.8s @4GeV/c

BELLE Upgrade: Super B factory three radiators: Aerogel, C4F10 and CF4.

H.Haba, S.Korpar

  • Tests done with aerogel radiator

    producing Cherenkov photons from

    a cosmic ray setup and Hamamatsu SiPM

RICH with Gas based photodetectors three radiators: Aerogel, C4F10 and CF4.

  • CLEO-c Experiment : Charm Physics at CESR : p /K separation up to 3 GeV/c .

    LiF radiator with 20 m 2 of CH4+TEA in MWPC.

  • ALICE experiment:

  • Physics of Strongly interacting matter, QGP

  • in nucleus-nucleus collisions at LHC.

  • p /K separation in 1 5 GeV/c

  • 11 m2 of CSI photocathode

  • gain < 10 5

  • Ready to take data

  • At high event rates the gain is limited by the photon and ion feed

    back problems.


ALICE Upgrade: Simulation three radiators: Aerogel, C4F10 and CF4.

  • New version of gas based detectors are being developed:

    GEM detectors : 0.31.6 ns readout time.

  • ALICE:

  • Simulation: Mirror ROC 240 cm, Photons

    focusing on a plane at ROC/2.





Result of ALICE upgrade simulation

R.Chechik three radiators: Aerogel, C4F10 and CF4.

Gas based Detectors


  • PHENIX: Identify electron pairs coming from relativistic heavy ion

  • collisions at sqrt(s)= 200 GeV for Au-Au.

  • Background from charged hadrons, electron-positron pairs from

  • g conversions and p 0 Dalitz decays in the invariant mass

  • range < 1GeV/c2

  • HBD features: No windows: Photons create blobs of hits in the GEM

  • Hadron Blind: Hadrons produce only ionization signal which

  • are then suppressed.

Summary three radiators: Aerogel, C4F10 and CF4.

  • The field of RICH detectors is still evolving. Several new detectors are ready to

  • take data or are planned to be constructed.

  • New types of photodetectors: Flat Panel PMTS, Silicon photomultipliers and GEMs

  • have the potential to improve the performance of the next generation of RICH detectors.

  • Novel Detector configurations like Focusing DIRC, Focusing Aerogel tiles

  • can also enhance the performance of the RICH systems.

EXTRA SLIDES three radiators: Aerogel, C4F10 and CF4.

COMPASS UPGRADE three radiators: Aerogel, C4F10 and CF4.


  • Spin structure of the nucleon,

    gluon polarization

  • Open charm produciton leading to D mesons.

    D0  K - p +

  • At high rates, lot of background hits seen

  • in the very forward region in MWPC.

  • Expected increase in trigger rate 20100 kHz

  • Replace the central region with MAPMT

COMPASS Upgrade three radiators: Aerogel, C4F10 and CF4.