Post on 30-Dec-2015
Comparison of Endcap CID-PID
Klaus Föhl
PID meeting 27/3/2007
panda-meeting Genova
• Focussing Lightguides
• Time-of-Propagation
• Proximity Focussing
Focussing Lightguides
focalplanecoord.[mm]
lightguide number
Focussing Lightguides
• short focal plane 50mm• ~1mm pixels needed• optical errors exist• thicker plate a problem• 125mm disc-PMT
• focal plane 100mm• pixel width 2-3mm• benign optics• thicker plate ok• 200mm disc-PMT
Focussing Lightguides
no LiF plate
Focussing Lightguides
no LiF plate
LiF plate
performance decreasedue to poor phi resolutionfor particle track near the edge,partial remedy to be investigated
N.B. only rough matching of current geometry
homework: for photon areaof large angle tracksincrease phi resolutionby subdividing pixel length
all calculations: =300nm-600nm Quantum Efficiency 20% n0=15.28/mm
optimisation within the sum rule 6K pixels
Time-of-Propagation
• already investigated– excess radius– pixelisation effectfall-off at larger angle
• to investigate– rectangular hole– different hole coatingsproper ray-tracing– several outer shapes– path ambiguties (with similar travel time)
r=900mm and 1100mm
r=900mm (23deg equivalent) 30ps512 pixels256 pixel128 pixel
notrelevant
notrelevant
Time-of-Propagation
hexagon with rectangular hole
ToP disc Gießen DesignSaclay version:hexagonal shaperectangular black hole
reflective hole absorbing hole
8 degphoton number corresponding to 54 tracks
Time-of-Propagation
TOP =70ps N0=344 n0=17.19/mm[ref: Markus Ehrenfried, Saclay talk]
hexagon with rectangular hole
circle black rectangle
circle mirror rectangle
hexagon mirror rectangle
hexagon black rectangle
circular with rectangular hole
comparison:hexagon 960mm width or round disc 1100mm radius
t=30ps
Time-of-Propagation
• single photo timing crucial
• performance increase comes with more tracks in the time-angle-plane
reflective hole absorbing hole
16 deg
these calculations: =400nm-800nm Quantum Efficiency 30% n0=17.19/mm per band: n(group)=0.0213 (inspired by [480nm-600nm] n=0.00615
Proximity Focussing
design variationwith mirror andthe expansionvolume upstreamradiator placed closer to EMC
Proximity Focussing
C6F14+CsI+GEM
radiator 15mmexpansion 135mm[no] mirror
Proximity Focussing
detection plane needs to be largerthan the radiator size to catch allphotons on the possible cones
ormirrors at the fringesto fold Cherenkov coneback onto the active area
design variationwith mirror andthe expansionvolume upstreamradiator placed closer to EMC
Performance comparison
focussing lightguide
ToP
C6F14+CsI+GEM
radiator 15mmexpansion 135mm[no] mirror
Performance comparison
radiatorX0[]@QEn0 [1/mm]N0
N0*sin^2*geometry
pixels
photon rate..per area..per pixel
Focussing15mm SiO2
12%300nm-600nm@20%15.28225/cos12166
6K
4E9 1/s1.25E6 1/s/cm^20.66E6 1/s/pixel
ToP20mm SiO2
16%400nm-800nm@30%17.19344/cos185100 (75)
1K (?)
6E9 1/s4.5E6 1/s/cm^2 (100%)6E6 (?) 1/s/pixel
Proximity15mm C6F10
7% (+window)
4024-40
3E4 – 1.2E5
2.4E8 1/s~1E4 1/s/cm^2
Cherenkov photons N=d*n0*sinC^2=N0*sinC^2 lightguide PMT 128* 25cm2 2E7 interactions/s ; multiplicity 6 ; Endcap region ~50% in CM 6E7 particles/s
Time-of-Propagation
Proximity Focussing
Proximity Focussing
Proximity Focussing
Photon yield – visible photons
phot
ons p
rodu
ced
in ra
diato
r
plus CsI
quantum efficiency
absorption plusquantum efficiency
20mm
10mm
curves show photon yield for an energy intervalstarting at E_photon=5.4eV
r.home.cern.ch/r/richrd26/www/hmpid/richsim.htmlmaterial properties from RICHSIM web page at CERN
Simulation ingredients
• proper Cherenkov photons number and colour
• refractive index dispersion– Cherenkov angles– Snell's law
• absorption length• quantum efficiency• statistical analysis
• normal incidence particles only maths simplification
• no angular straggling• liquid without vessel• no detector pixels
(assumed to be small)
• Fresnel formula simplified (Brewster angle being close)
• perfect mirror
Simplifications & Approximations
C6F14
CsI mirr
or
Hit pattern
response shape(1000 particles)
photons1 particle=0.99
The particle distance is the average of the photon radial distancesresulting from one charged particle. Particle distance mean and sigmaare computed for samples of 1000 events =1 and 1000 events =0.99and sigma separation & 4-limit derived.
Performance comparison
focussing lightguide
ToP
C6F14+CsI+GEM
radiator 15mmexpansion 135mm[no] mirror
potential edge effects
detection plane needs to be largerthan the radiator size to catch allphotons on the possible cones
ormirrors at the fringesto fold Cherenkov coneback onto the active area
design variationwith mirror andthe expansionvolume upstreamradiator placed closer to EMC
performance – radiator width
angle dependence
preliminary and approximate calculation
source of material properties
• material data used is shown left and below
• from a RICHSIM web page at CERN
r.home.cern.ch/r/richrd26/www/hmpid/richsim.html
material transmission
radiator thickness
Comparison of Endcap PID
Time-of-Propagation
TOP =30ps N0=344 n0=7.64/mm