1. The DIRC projects of the PANDA experiment at FAIR
Klaus Föhl on behalf of the
Work supported
by EU FP6 grant
contract number
DIRACsecondary-Beams
RICH2007
Trieste, Italy
October 2007
Cherenkov Group
Darmstadt Dubna Edinburgh Erlangen Ferrara Giessen Glasgow Krakow Wien

2. Antiprotons HESR Hadron spectroscopy Nuclei Far From Stability
- Charmonium spectroscopy
- Gluonic excitations (hybrids, glueballs)
Charmed hadrons in nuclear matter
Double -Hypernuclei
Nuclei Far From Stability
Compressed Nuclear Matter
High Energy Density in Bulk
Antiprotons

3. A View of PANDA AntiProton ANnihilations at DArmstadt p Forward
Spectrometer
Target
Spectrometer p

4. A View of PANDA AntiProton ANnihilations at DArmstadt High Rates
2 107 interaction/s
Vertexing
KS0, Y, D, …
Charged particle ID
e±, μ±, π±, K, p,…
Magnetic tracking
EM. Calorimetry
γ,π0,η
Forward capabilities
leading particles
Sophisticated Triggers

5. Particle ID & Kinematics
pp i.e. open charm production
pp  KK T=5,10,15 GeV/c +
K  
  
K K 
  K even
or K     - + D
pp  DD D  Kpp
T=6.6 GeV/c
distinguish  and K (K and p) ...

6. PANDA Target Spectrometer
Acceptance for
pp  h  @ 15 GeV
End- cap
Barrel
Endcap
Barrel
PANDA: 4 detector desire to keep EMC small  hence we suggest DIRCs FS
Target Spectrometer
two areas – two detector geometries

7. ...shipping coal to Newcastle...
...talking about DIRC at RICH...

8. DIRC Principles <1 =1 Detector of Reflected lower p threshold
Internally
Reflected
Cherenkov light
lower p threshold n p K 
solid DIRC
n=1.47
<1 
=1  K p
15 deg
<1
Time-of-Propagation for C
fused silica
10mm 0.4eV
=1

9. Barrel DIRC Barrel-DIRC BaBar-like 2D + t or (2+1)D design
2-dimensional
imaging type
Poster  Carsten Schwarz: The Barrel DIRC of the PANDA experiment

10. PANDA barrel DIRC scaled BaBar version suits PANDA “only” 7000 PMT
(BaBar PMT)
Simulations
pp →J/ψ Φ √s = 4.4 GeV/c2
kaon efficiency 98%
π misidentification
as kaon 1-2%

11. PANDA barrel DIRC R&D towards smaller photon detector
needs optical elements instead of pinhole focus
mirrors
lenses
focal plane
detector
two lenses for flat focal plane
Oil
H2O
air
SiO2
quartz bar
air
mirrors

12. PANDA barrel DIRC y x fused silica close to threshold: β=0.69
small variations in n(λ)
cause large δΘ
cos(Θ)=1 / βn(λ)
β=0.72
Time of Propagation (TOP) measurement better 0.5ns
allows to correct dispersion
for high and low momenta→x,y,t→3D-DIRC x Y

13. PANDA Target Spectrometer
Two different readout designs:
Time-of-Propagation
Focussing Lightguide
(1+1)D design
2D + t design
Endcap Disc DIRC
1-dimensional
imaging type
Poster  Peter Schönmeier: The Endcap DIRC of the PANDA experiment

14. Dispersion Corrections
different directions
for different colours
ToP
for a given time t different horizontal
distances for different photon colours
Focussing – Solution:
ToP – Solution:
relevant
for ToP
narrow bands
in wavelength
dispersive prism
component

15. Time-of-Propagation design
colour filters
dichroic mirrors as colour filters
allows two wavelength bands
higher photon statistics
small wavelength bands
minimise dispersion effect
+optimised photocathodes
mirrors
mirrors give different path lengths
 self timing design
reflect
some
photons
several
different
path lengths
mirrors allow longer path lengths
 better relative time resolution
20mm fused silica
radiator disc
single photon resolution t~30-50ps required

16. Time-of-Propagation design
larger text
0 reflections
1 reflection
2 reflections
3 reflections
50 events
time-of-propagation [ns]
 [deg]

17. Time-of-Propagation particle angle 15 deg t=50ps
E x QE=( )eV
disc with black hole

18. Focussing Lightguide * * * * radiator edge LiF SiO2 photo sensor
strips
fused silica (SiO2)
radiator 10-15mm
* discrete lightguide no.
* angle in (r-z) plane
LiF for dispersion correction
photon extraction into lightguide
lifts up-down direction ambiguity
focussing inside lightguide * *
lightguides

19. Focussing & Chromatic Correction
no mirror coating
1-dim aspheric surface
total internal reflection
angle independent of 
not-perfect
focussing as
curvature is
compromise
(but good enough)
light is only
going upwards
two boundary surfaces make
chromatic dispersion correction
angle-independent in first order
light never leaves
dense optical medium
 good for phase space
Focal Plane
(dispersive direction)
1-dimensional readout

20. Focussing Lightguide simulation example with 2 fit analysis
target
vertex 
 [deg]
simulation example with 2 fit analysis
disc 10mm thick, 0.4eV
short lightguide 125mm, focal plane 48mm

21. Research & Development
Polishing Effectiveness
Radiator Tests
Radiation Hardness
Photon Detectors
AFM
30m x 30 m
5.46 nm
full vertical scale
Friday  Matthias Hoek: Radiation Hardness Study on Fused Silica
magnetic field (up to B=2T), photon rate (MHz/pixel),
light cumulative dose, radiation dose
Thursday  Albert Lehmann: Performance Studies of Microchannel Plate PMTs in High Magnetic Fields

22. Summary High antiproton rates require novel detectors for PID
We propose DIRCs for the PANDA Target Spectrometer FS TS
Several designs with innovative solutions
Barrel DIRC with optical elements
Endcap DIRC – Time-of-Propagation
Endcap DIRC – Focussing Lightguide
R&D in progress

23. Panda Participating Institutes
more than 300 physicists (48 institutes) from 15 countries
U Basel
IHEP Beijing
U Bochum
U Bonn
U & INFN Brescia
U & INFN Catania
U Cracow
GSI Darmstadt
TU Dresden
JINR Dubna (LIT,LPP,VBLHE)
U Edinburgh
U Erlangen
NWU Evanston
U & INFN Ferrara
U Frankfurt
LNF-INFN Frascati
U & INFN Genova
U Glasgow
U Gießen
KVI Groningen
U Helsinki
IKP Jülich I + II
U Katowice
IMP Lanzhou
U Mainz
U & Politecnico & INFN Milano
U Minsk
TU München
U Münster
BINP Novosibirsk
LAL Orsay
U Pavia
IHEP Protvino
PNPI Gatchina
U of Silesia
U Stockholm
KTH Stockholm
U & INFN Torino
Politechnico di Torino
U Oriente, Torino
U & INFN Trieste
U Tübingen
U & TSL Uppsala
U Valencia
IMEP Vienna
SINS Warsaw
U Warsaw