Transcript endcap.assess.genova2

Comparison of Endcap CID-PID
Klaus Föhl
PID meeting 27/3/2007
panda-meeting Genova
• Focussing Lightguides
• Time-of-Propagation
• Proximity Focussing
Focussing Lightguides
focal
plane
coord.
[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
all calculations: =300nm-600nm Quantum Efficiency 20% n0=15.28/mm
LiF plate
performance decrease
due to poor phi resolution
for particle track near the edge,
partial remedy to be investigated
no LiF plate
N.B. only rough matching
of current geometry
optimisation within the sum rule 6K pixels
homework: for photon area
of large angle tracks
increase phi resolution
by subdividing pixel length
Time-of-Propagation
• already investigated
– excess radius
– pixelisation effect
fall-off at larger angle
r=900mm and 1100mm
not
relevant
• to investigate
– rectangular hole
– different hole coatings
proper ray-tracing
– several outer shapes
– path ambiguties
(with similar travel time)
r=900mm (23deg equivalent) 30ps
512 pixels
256 pixel
128 pixel
not
relevant
Time-of-Propagation
ToP disc Gießen Design
Saclay version:
hexagonal shape
rectangular black hole
hexagon with
rectangular hole
reflective hole
absorbing hole
8 deg
photon number corresponding to 54 tracks
Time-of-Propagation
comparison:
hexagon 960mm width or round disc 1100mm radius
TOP =70ps N0=344 n0=17.19/mm
[ref: Markus Ehrenfried, Saclay talk]
hexagon with rectangular hole
t=30ps
hexagon mirror rectangle
circle mirror rectangle
hexagon black rectangle
circle black rectangle
circular with rectangular hole
Time-of-Propagation
these calculations: =400nm-800nm Quantum Efficiency 30% n0=17.19/mm
per band: n(group)=0.0213 (inspired by [480nm-600nm] n=0.00615
reflective hole
absorbing hole
• single photo timing
crucial
• performance
increase comes with
more tracks in the
time-angle-plane
16 deg
Proximity Focussing
design variation
with mirror and
the expansion
volume upstream
radiator placed
closer to EMC
Proximity Focussing
C6F14+
CsI+GEM
radiator 15mm
expansion 135mm
[no] mirror
Proximity Focussing
design variation
with mirror and
the expansion
volume upstream
radiator placed
closer to EMC
detection plane needs to be larger
than the radiator size to catch all
photons on the possible cones
or
mirrors at the fringes
to fold Cherenkov cone
back onto the active area
Performance comparison
radiator 15mm
expansion 135mm
[no] mirror
focussing lightguide
C6F14+
CsI+GEM
ToP
Performance comparison
radiator
X0
[]@QE
n0 [1/mm]
N0
N0*sin^2
*geometry
Focussing
15mm SiO2
12%
300nm-600nm@20%
15.28
225/cos
121
66
ToP
20mm SiO2
16%
400nm-800nm@30%
17.19
344/cos
185
100 (75)
Proximity
15mm C6F10
7% (+window)
pixels
6K
1K (?)
3E4 – 1.2E5
photon rate
..per area
..per pixel
4E9 1/s
1.25E6 1/s/cm^2
0.66E6 1/s/pixel
6E9 1/s
4.5E6 1/s/cm^2 (100%)
6E6 (?) 1/s/pixel
2.4E8 1/s
~1E4 1/s/cm^2
40
24-40
Cherenkov photons N=d*n0*sinC^2=N0*sinC^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
material properties from RICHSIM web page at CERN
r.home.cern.ch/r/richrd26/www/hmpid/richsim.html
20mm
absorption plus
quantum efficiency
curves show photon yield for an energy interval
starting at E_photon=5.4eV
CsI
mirror
C6F14
Simulation ingredients
Simplifications & Approximations
• normal incidence particles only
 maths simplification
• no angular straggling
• proper Cherenkov photons • liquid without vessel
number and colour
• no detector pixels
• refractive index dispersion
(assumed to be small)
– Cherenkov angles
• Fresnel formula simplified
– Snell's law
• absorption length
• quantum efficiency
• statistical analysis
(Brewster angle being close)
• perfect mirror
Hit pattern
photons
1 particle
=0.99
response shape
(1000 particles)
The particle distance is the average of the photon radial distances
resulting from one charged particle. Particle distance mean and sigma
are computed for samples of 1000 events =1 and 1000 events =0.99
and sigma separation & 4-limit derived.
Performance comparison
radiator 15mm
expansion 135mm
[no] mirror
focussing lightguide
C6F14+
CsI+GEM
ToP
potential edge effects
design variation
with mirror and
the expansion
volume upstream
radiator placed
closer to EMC
detection plane needs to be larger
than the radiator size to catch all
photons on the possible cones
or
mirrors at the fringes
to fold Cherenkov cone
back onto the active area
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