1 / 23

A RICH detector for CLAS12

Hall B. Central Detector. Forward Detector. A RICH detector for CLAS12. Evaristo Cisbani INFN Rome and ISS Patrizia Rossi INFN- Laboratori Nazionali di Frascati. CLAS12 European Workshop February 25-28, 2009- Genova, Italy. Ratio K/  ~ 0.1-0.15

oderrick
Download Presentation

A RICH detector for CLAS12

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Hall B Central Detector Forward Detector A RICH detector for CLAS12 Evaristo Cisbani INFN Rome and ISS Patrizia Rossi INFN- Laboratori Nazionali di Frascati CLAS12 European Workshop February 25-28, 2009- Genova, Italy

  2. Ratio K/ ~ 0.1-0.15 • If we assume a 10%  inefficiency for Cerenkov rejection factor /k ~1:1 RICH detector Hadron PID in CLAS12 Baseline • p/K PID rely on LTCC performance in 3-5 GeV/c • No K/p PID in 5-8 GeV/c

  3. 2 L RICH detector r P = 2 GeV/c L= 1m n=1.28 (liquid freon) Good separation /K/p

  4. Which RICH? • Liquid Radiator (Freon) • May cover up to 5 GeV/c • Relatively inexpensive (proximity focusing RICH) • Aerogel + Gas Radiators • May cover up to 10 GeV/c • Very expensive • (cost Aerogel RICH ~ 5x Proximity Focusing RICH)

  5. Replace part of LTCC: • No impact on baseline design • Nobody will probably complain • Large space available (and to be covered!) • Replace HTCC: • Impact on baseline design • Impact on tracking recontruction Simulation done for LTCC Location of the RICH

  6. 1 m depth ~ 6.2 m2 entrance window LTCC sector

  7. Hall A Proximity RICH • A proximity Focusing RICH (~1 m2 surface) is working in Hall A and being used in the Transversity experiment • Same RICH type used by ALICE experiment ( ~10 m2 surface)

  8. Cherenkov Liquid Radiator Gap (gas filled space) Photon Detector Proximity Focusing RICH The Proximity Focusing RICH consists of 3 basic components: The Radiator must be in a container (vessel) with UV transparent window (QUARTZ window) The Photon Detector must detect and localize the photon that hits on a given surface: we assume a “pads like” detector

  9. Evaporation facility • CsI is evaporated on the pad panel in • the evaporation chamber: 120h x 110r • cm2 (vacuum 10-7 mbar) • The evaporation facility - cost ~ 0.5 M$ has been built by the INFN Rome group (now at Stony Brook University) • The Freon vessel (radiator) is the most • fragile component of the detector • The Freon pressure is partially • compensated by the glued spacers • Quarz planarity and parallelism 0.1 mm Hall A Proximity RICH

  10. Hall A RICH: QE measurements (July ‘08) 25 ~ 25% Quantum Efficiency has been measured 25

  11. Hall A RICH in Hypernuclear Exp. (2003-2005)  K/p rejection ~ 1/1000 F. Garibaldi et al. NIM A502 (2003)

  12. Monte Carlo studies: purpose • Estimate the optimal radiator thickness • Larger the thickness, higher the number of photons, • higher the uncertainties on photon emission • Larger the thickness more challenging is the vessel • technology (and more expensive the system) • Estimate the optimal Gap length • Larger the gap, better the ‘focusing’, but larger must • be the detection plane

  13. Monte Carlo studies: framework • Old GEANT3/Fortran/PAW based MonteCarlo framework the same used the for the development of the Hall A Proximity RICH but with different geometry and size! • Charged particles phase space at the LTCC-RICH entrance window assumed uniformly distributed with +/- 10 degree divergence • Use arcs as radiator and detector geometries (see next) • Limitation on photon production (~3000) old memory constraint.This becomes relevant for radiator thickness > 2.5-3.0 cm Main output parameter: skp= mean error on Cherenkov angle reconstruction of k and p   K-= (K+ )/2 CK C

  14. Working Point Not to scale Unit: mm and degree • Assume: • Two radiators (only 1 simulated); one per sector • Detector span up to 2 sectors (detect photons from both radiators) • Radiator Polar acceptance: 5° ÷30°  fix radiator size ~ 4 m2 • Max gap length = 80 cm

  15. Monte Carlo Result: Example • Particles uniformely distributed in the phase space • Black dots are charged particle positions at RICH entrance (the envelope is the radiator) • Contour lines are positions at the detector level of all photons generated in the radiator • The large arc is the detector surface (photons out of there are not detected) • Geometry is rotated respect to the previous drawing … but represent basically the same idea x/y are not to scale

  16. n   C C Geometry from the previous example Radiator Type C5F12 C6F14 ~ 1 mr difference  C5F12 mandatory! Points: MonteCarlo, Curves: analytical functions

  17. (GeV/c) Simulation with realistic phase space To detemine the best photon detector size, ,K,p have been generated at the LTCC-RICH entrance window according with a realistic phase space distribution of reconstructed momenta and angles.

  18. Radiator= 1.5 cm Radiator= 2 cm Radiator= 3 cm K- Separation Angle reconstruction error vs: • Radiator Thickness = 1.5, 2, 2.5, 3, 3.5 cm • Gap length = 80 cm • Pad/Pixel size = 0.75 cm 100k events

  19. Gap Length= 80 cm Gap Length= 60 cm K- Separation Angle reconstruction error vs: • Radiator Thickness = 2 cm • Gap length = 60, 80 cm • Pad/Pixel size = 0.75 cm 100k events Separation at 5 GeV/c:3  = 1/100 / 75% efficiency 1/10 / 95% efficiency

  20. Radiation thickness Total radiation thickness of the proposed RICH: ~20% X0

  21. Photon Detector • Replace MWPC with GEM Chamber • faster, • higher gain, • stability at high rate HBD @ Phenix

  22. Costs - Very Preliminary!! Class12/Hall A Radiator: 36-48 (min.-max. volume), 24 (surface) Detector: 13 (surface), 4 (chs) k$ (estimation from Lire, CHF, $ and Euro) GEM ~ 1.2 x MWPC

  23. Conclusions and outlook • Monte Carlo simulations have been started to study the feasibility to replace 2 sectors of LTTC with a proximity focusing RICH detector • From very preliminary results it seems that: • The best choice is to use Freon C5F12 but it must be cooled! (it evaporate at 29 C at STP !!) • At present stage the Cherenkov angle resolution is not impressive • a careful analysis and design is required to improve both the performance and the detector size • orientation of radiator • pad size • … • work is in progress

More Related