1. RICH simulation for CLAS12
Hall B
Central
Detector
Forward Detector
Contalbrigo Marco
INFN Ferrara
Luciano Pappalardo
M. Contalbrigo
JLAB12 coll. Meeting 18 Nov 09 1

2. Mean pk separation (4.5-5 GeV)
Pad size 2 cm
Pad size 0 cm
VISIBLE light
Pad size 2 cm
UV+VIS light
UV light
The hybrid photon detector option
M. Contalbrigo
JLAB12 coll. Meeting 18 Nov 09 2

3. Status and outlook Hybrid (visible + UV photons) solution
C6F14 + visible light should satisfy ID requirements with small pad size
High cost for photon detection
High material budget affecting TOF
Hybrid (visible + UV photons) solution
- will probabily require reduced UV fraction
- affects anyway TOF
C5F12 (UV photons) solution
- will probabily resemble C6F14 + UV light
- technologically challenging
C6F14 (selected UV photons) solution
- reduced chromatic error
- balance with reduced number of photons
Effect of PMT plane on TOF with Geant 3?
M. Contalbrigo
JLAB12 coll. Meeting 18 Nov 09 3

4. Status and outlook
C6F14 + visible light should satisfy ID requirements with small pad size
High cost for photon detection
High material budget affecting TOF
Cerenkov TOF a-la PANDA
- faster than scintillator light
- single photon collection allows for refined photon-path corrections
in principle sensitive to the Cerenkov angle
Mirror solution (photon detector outside particles trajectories)
- reflecting upward toward larger radius
- reflecting on a side toward toroid shadows
Toward real experimental conditions
p,p,k with their specific spectra
Real particle multiplicity
M. Contalbrigo
JLAB12 coll. Meeting 18 Nov 09 4

5. Time-of-flight disc RICH
It measures Cherenkov light that is generated and internally reflected in a 2 cm thick
fused silica plate. The Cherenkov angle is reconstructed from a time-of-propagation measurement at the rim of the disc of individual Cherenkov photons with a resolution of better than 50 ps. Dichroic mirrors at the rim of the disc fulfil two purposes. They allow for a selection of certain wavelength bands and thus are used to reduce dispersive smearing, and they enlarge the average photon path length by reflection and thus improve the separation power of the detector.
M. Contalbrigo
JLAB12 coll. Meeting 18 Nov 09 5

6. Time-of-flight disc RICH
Possible hadron ID at large photon paths (and limited momentum)
Why not to use it as a TOF ?
Photon detector on the side of the sector (< 1 m2)
M. Contalbrigo
JLAB12 coll. Meeting 18 Nov 09 6

7. Time-of-flight disc RICH
Vertical quartz slab, 3 cm thick
Photon detector all around slab edge
M. Contalbrigo
JLAB12 coll. Meeting 18 Nov 09 7

8. Time-of-flight disc RICH
P=1.9 GeV/c
Quartz light attenuation length = 500 cm
Number of detected photons ~ 150
M. Contalbrigo
JLAB12 coll. Meeting 18 Nov 09 8

9. Time-of-flight disc RICH
P=4.2 GeV/c
Reduced photon detection area ( < 1 m2 per sector)
Minimized effect on standard TOF
Compatible with a standard (UV?) RICH
M. Contalbrigo
JLAB12 coll. Meeting 18 Nov 09 9

10. Time-of-flight disc RICH
Vertical quartz slab, 3 cm thick
Photon detector all around slab edge
M. Contalbrigo
JLAB12 coll. Meeting 18 Nov 09 10

11. RICH detector ratio K/ ~ 0.1-0.15 p/K p/p K/p 3 cm 80 cm
Substitute 2 LTCC
sectors with a proximity RICH detector
3 cm
80 cm
GeV/c 1 2 3 4 5 6 7 8 9 10
p/K
TOF
LTCC
HTCC
p/p
K/p
ratio K/ ~
M. Contalbrigo
JLAB12 coll. Meeting 18 Nov 09 11

12. 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.
(GeV/c)
M. Contalbrigo
JLAB12 coll. Meeting 18 Nov 09 12

13. Refraction index: freon
Simulation based on most conservative n (Moyssdes)
M. Contalbrigo
JLAB12 coll. Meeting 18 Nov 09 13

14. Refraction index: quartz
Quartz absorption length and refraction index from
Khashan and Nassif, Optic communications 188 (2001) 129
M. Contalbrigo
JLAB12 coll. Meeting 18 Nov 09 14

15. Geometry : 1 Assume: Two radiators (only 1 simulated); one per sector
Not to scale
Unit: mm and degree
Assume:
Two radiators (only 1 simulated); one per sector
Detector covers up to 2 sectors (detect photons from both radiators)
Radiator Polar acceptance: 5° ÷30°  fix radiator size ~ 4 m2
Max gap length = 120 cm
M. Contalbrigo
JLAB12 coll. Meeting 18 Nov 09 15

16. Geometry : 2 Space for support and neoceram ?
Quartz (0.5cm)
Space for support and neoceram ?
Minimum radius fixed by 5o requirement ?
How to define maximum radius ? B’
freon K
Study gap depth and freon thickness
20° B C’
gap
90° C
35° A’
25° A O 5°
beam line H H’
M. Contalbrigo
JLAB12 coll. Meeting 18 Nov 09 16

17. Photon detector Hamamatsu R7400-U03: 18 mm diam., 12 mm length
0.8 x 0.8 cm2 pixel, 50 % packing density
Spectral range nm, max q.e. at 420 nm
~0.1 keu each: 1 m2 costs about 250 keuro
Hamamatsu H8500/H9500: 52 mm square.
0.6 x 0.6 cm2 pixel, 89 % packing density
Spectral range nm, 25 % q.e. at 420 nm
~1.5 keu each: 1 m2 costs > 500 keuro
Hamamatsu R M16: 26 mm square.
0.5 x 0.5 cm2 pixel, 50 % packing density
Spectral range nm, max q.e. at 420 nm
~0.5 keu each: 1 m2 costs about 700 keuro
M. Contalbrigo
JLAB12 coll. Meeting 18 Nov 09 17