Bernd Lewandowski
Ruhr-Universität Bochum
SCINT 2003
Valencia
11. 9. 2003
A Fast and Compact Electromagnetic
Calorimeter for the
Detector at GSI
What is PANDA?
AntiProton
ANnihilations
at DArmstadt
11. 9. 2003
Bernd Lewandowski - Ruhr-Universität Bochum - SCINT 2003
2
Where is Darmstadt?
GSI
11. 9. 2003
Bernd Lewandowski - Ruhr-Universität Bochum - SCINT 2003
3
The GSI Future Facility
Panda
Existing GSI Facilities
11. 9. 2003
Bernd Lewandowski - Ruhr-Universität Bochum - SCINT 2003
4
Antiproton Physics Program
Charmonium (cc ) spectroscopy: precision measurements of mass,
width, decay branches of all charmonium states, especially for extracting
information on qq models of mesons.
11. 9. 2003
Bernd Lewandowski - Ruhr-Universität Bochum - SCINT 2003
5
Antiproton Physics Program
Charmonium (cc ) spectroscopy: precision measurements of mass,
width, decay branches of all charmonium states, especially for extracting
information on qq models of mesons.
Search for gluonic excitations (charmed hybrids, glueballs)
in the charmonium mass range (3 – 5 GeV/c2).
11. 9. 2003
Bernd Lewandowski - Ruhr-Universität Bochum - SCINT 2003
6
Antiproton Physics Program
Charmonium (cc ) spectroscopy: precision measurements
of mass,
pionic atoms
width, decay branches of all charmonium states, especially for extracting
information on qq models of mesons.

KAOS/FOPI
Search for gluonic excitations (charmed hybrids,
glueballs)
in the charmonium mass range (3 – 5 GeV/c2).
K
Search for modifications of meson properties in the nuclear medium,
and their possible relationship to the partial restoration of chiral
HESR
symmetry for light quarks.
π25 MeV
π+
K+
100 MeV
K-
D
D50 MeV
D+
vacuum nuclear medium
  0
11. 9. 2003
Bernd Lewandowski - Ruhr-Universität Bochum - SCINT 2003
7
Antiproton Physics
Program
KK
Antiproton
Physics Program
p
Trigger
_
Charmonium (cc ) spectroscopy: precision measurements of mass,
X
width, decay branches of all charmonium states, especially for extracting
3 GeV/c
information on qq models of mesons. X-
Search for gluonic excitations (charmed hybrids, glueballs)
in the charmonium mass range (3 – 5 GeV/c2).
Search for modifications
of mesontarget
properties in the nuclear medium,
secondary
and their possible relationship to the partial restoration of chiral
symmetry for light quarks.
X-(dss) p(uud) → L(uds) L(uds)
vacuumnuclear medium
p
K
p25+ MeV
p
K+
100 MeV
K-
D
D50+MeV
D
Precision g-ray spectroscopy of single and double hypernuclei for
Extracting information on their structure and on the hyperon-nucleon
and hyperon-hyperon interaction.
11. 9. 2003
Bernd Lewandowski - Ruhr-Universität Bochum - SCINT 2003
8
The Antiproton Facility
11. 9. 2003
Bernd Lewandowski - Ruhr-Universität Bochum - SCINT 2003
9
The Antiproton Facility
• Antiproton production similar to CERN,
• HESR = High Energy Storage Ring
– Production rate 107/sec
– Pbeam
= 1.5 - 15 GeV/c
– Nstored = 5 x 1010 p
• Gas-Jet (or Cluster) Target
• High luminosity mode
– Luminosity
= 2 x 1032 cm-2s-1
 Dp/p ~ 10-4 (stochastic cooling)
• High resolution mode
 Dp/p ~ 10-5 (electron cooling < 8 GeV/c)
– Luminosity
= 1031 cm-2s-1
11. 9. 2003
Bernd Lewandowski - Ruhr-Universität Bochum - SCINT 2003
10
Proposed Detector (Overview)
• High Rates
– Total s ~ 55 mb
– 107 interactions/s
• Vertexing
– (sp,KS,L,…)
• Charged particle ID
– (e±,m±,p±,p,…)
• Magnetic tracking
• Elm. Calorimetry
– (g,p0,h)
• Forward capabilities
– (leading particles)
• Sophisticated Trigger(s)
11. 9. 2003
Bernd Lewandowski - Ruhr-Universität Bochum - SCINT 2003
11
Electromagnetic Calorimeter
Detector material
PbWO4
Photo sensors
Avalanche Photo Diodes
Crystal size
 35 x 35 x 150 mm3 (i.e 1.5 x 1.5 RM2 x 17 X0)
Energy resolution
1.54 % / E[GeV] + 0.3 % (PMT)
Time resolution
s  130 ps (PMT)
Total number of crystals
7150
11. 9. 2003
Bernd Lewandowski - Ruhr-Universität Bochum - SCINT 2003
12
Requirements for the EMC
• Nearly 4p solid angle (PWA)
• High rate capability: 107 interactions/s
• High resolution: 1.54 % / E[GeV] + 0.3 %
• Compact design: inside Solenoid
• Operation in magnetic field: 2T
11. 9. 2003
Bernd Lewandowski - Ruhr-Universität Bochum - SCINT 2003
13
Lessons from LEAR (CB)
• Final states with 10+ photons
• Merged p0 are easy to handle
– “moderate” angular resolution sufficient
• Low thresholds
Crystal Barrel
– Emin≤20 MeV
11. 9. 2003
Bernd Lewandowski - Ruhr-Universität Bochum - SCINT 2003
14
Available Inorganic Scintillators
Property
CsI(Tl)
CeF3
PbWO4
BGO
Density [g/cm3]
4.53
6.16
8.28
7.13
Rad. length [cm]
1.85
1.68
0.89
1.12
Molière rad [cm]
3.8
2.63
2.19
2.33
dE/dx [MeV/cm]
5.6
7.9
13.0
9.2
Decay time [ns]
1000
10-30
5-15
60-300
Max. emission
[nm]
565
310-340
420-440
480
Rel. lightyield
0.40
0.10
0.01
0.15
11. 9. 2003
Bernd Lewandowski - Ruhr-Universität Bochum - SCINT 2003
15
PWO
• Fast Scintillator
• Allows a very compact design
• Low cost material
• But: light yield too low for detection
of low energy photons
• Improvement of light yield
• Cooling (LY changes with temperature)
11. 9. 2003
Bernd Lewandowski - Ruhr-Universität Bochum - SCINT 2003
16
PWO Improvement
R. Novotny et al.,
II. Phys. Inst. GI
counts
photon response: Eg = 45 -770 MeV@MAMI
Eg=45.4 MeV
1000
500
s
1.41%

+ 0.90%
E
E[GeV]
s/E=5.3%
800
s/E=7.4%
1500
Eg=105.6 MeV
1000
counts [a.u.]
counts [a.u.]
2000
600
s t ~ 130ps
400
200
0
0
0
50
100
150
energy [a.u.]
200
0
50
100
energy / a.u.
150
200
250
300
energy [a.u.]
350
400
450
PMT
readout
Bogoroditsk TCP
further significant increase of light output achievable by:
PWO II
• improvement of growing technology
(exploiting large experience with CMS/ECAL production)
• optimum co-doping
CMS/ECAL
11. 9. 2003
Bernd Lewandowski - Ruhr-Universität Bochum - SCINT 2003
17
PWO Improvement
crystal imperfections:
•
•
•
•
cation vacancies (Pb)
anion vacancies (O)
insite oxygen
excess of doping ions
results based on EPR:
M.Korzhik et al., RINC, Minsk
A.Hofstaetter et al., I. Phys. Inst. GI
• Frenkel defects reduced ( factor >3)
• Pt identified - impact on quenching?
• oxygen based defects reduced
2000
counts
1500
1000
137Cs:
Cs-137
662 keV
L.Y.: 43 phe/MeV
„2 times CMS-standard“
500
0
0
100
200
300
400
500
600
@ T = 20°C
channel
11. 9. 2003
Bernd Lewandowski - Ruhr-Universität Bochum - SCINT 2003
18
PWO Cooling
PWO
line shape:
@T=200C
1= 6.5ns (97%)
2=30.4ns ( 3%)
1
0.9
T= -6C
T= -2C
Light fraction, arb. units
0.8
R. Novotny et al.,
II. Phys. Inst. GI
T= 9C
0.7
T= 14C
0.6
fraction of light yield
collected in different
integration gates at
various temperatures
0.5
0.4
0.3
0.2
PWO light yeild
0.1
90
0
0
80
20
40
60
80
100
120
140
160
180
200
Time, ns
70
LY, phe/MeV
60
50
change of light yield collected
within 100ns as a function of
temperature
40
30
20
10
0
-7
-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
T, Celsium degree
11. 9. 2003
Bernd Lewandowski - Ruhr-Universität Bochum - SCINT 2003
19
PWO Future
Ongoing developements in PWO production
will increase the light yield.
 Light yield improvement of PWO scintillation crystals for the
PANDA detector
A. Borisevich, V. Dormenev, A. Hofstaetter, V. Ligoun,
M. Kozhik, B. K. Meyer, R. Novotny
Combined with cooling and
maximum coverage of readout side by
photosensor can make PWO
the scintillator of choice for the PANDA EMC.
11. 9. 2003
Bernd Lewandowski - Ruhr-Universität Bochum - SCINT 2003
20
Photosensor
APD Hamamatsu S8664-55
5 mm
• „Photodiode with internal amplification“
• operates in B-Field
• High quantum efficiency
• Active area 5x5mm2
• Large experience with CMS/ECAL
 Extremely reliable and robust
• but: gain, dark current are temp.
dependend  DT < 1°C
Others to be investigated:
• Large Area APDs of other manufacturers
• Channel Plate Multipliers
• Vacuum Triodes, …
11. 9. 2003
Bernd Lewandowski - Ruhr-Universität Bochum - SCINT 2003
21
APD readout: CsI(Tl)
@ T = 0 °C
APD (Hamamatsu) readout
active area: (5 x 5) mm2
active area: Ø 10 mm
60 mm
60 mm
662 keV
PMT ( R1635 ) readout
Entries
Entries
137Cs
50 mm
50 mm
662 keV
ADC channel
s E Ε  16%
11. 9. 2003
ADC channel
s E Ε  29%
Bernd Lewandowski - Ruhr-Universität Bochum - SCINT 2003
22
APD Quantum Efficiency
BGO
CsI(Tl)
PWO
CeF3
11. 9. 2003
Bernd Lewandowski - Ruhr-Universität Bochum - SCINT 2003
23
Available Inorganic Scintillators
Property
CsI(Tl)
CeF3
PbWO4
BGO
Density [g/cm3]
4.53
6.16
8.28
7.13
Rad. length [cm]
1.85
1.68
0.89
1.12
Molière rad [cm]
3.8
2.63
2.19
2.33
dE/dx [MeV/cm]
5.6
7.9
13.0
9.2
Decay time [ns]
1000
10-30
5-15
60-300
Max. emission
[nm]
565
310-340
420-440
480
Rel. lightyield
0.40
0.10
0.01
0.15
We‘ll come back to this in a minute.
11. 9. 2003
Bernd Lewandowski - Ruhr-Universität Bochum - SCINT 2003
24
BGO
First tests with
L3 crystals:
 APD readout
Temp controlled
environment
DT=1°C
controlled humidity
30% rel.
11. 9. 2003
Bernd Lewandowski - Ruhr-Universität Bochum - SCINT 2003
25
APD readout: BGO
T=0°C
PMT R1635
511 keV
25 mm
1275 keV
s E Ε (511keV)  25%
s E Ε (1275keV)  14%
11. 9. 2003
22Na
25 mm
25 mm
Entries
22Na
Entries
APD
511 keV
25 mm
1275 keV
ADC channel
ADC channel
s E Ε (1275keV)  22.5%
Bernd Lewandowski - Ruhr-Universität Bochum - SCINT 2003
26
BGO time resolution
PANDA:
• 107 events/s  10 ns time resolution
• MC: max. single crystal rate: ~200·103/s
BGO timing test:
• L3 BGO crystal
• Hamamatsu APD
• BABAR preamp (250 ns shaping)
• Digital Scope
• Record a sample of cosmics signals (~15 MeV)
 Make a simple MC test
11. 9. 2003
Bernd Lewandowski - Ruhr-Universität Bochum - SCINT 2003
27
BGO time resolution
• Use Landau func.
to simulate pulses
Landau fit + DC offset
• Typical: N/S=0.5%
 Vary S/N and FADC
sampling freq.
• Linear fit of rising edge
• Determine time when fit
reaches half the signal
amplitude
11. 9. 2003
BGO
Linear fit
point of
time measurement
Bernd Lewandowski - Ruhr-Universität Bochum - SCINT 2003
28
BGO time resolution
σv [V]
0.01
0.02
0.03
0.04
0.01
0.02
0.03
0.04
0.01
0.02
0.03
0.04
11. 9. 2003
N/S [%]
0.5
1.0
2.0
5.0
0.5
1.0
2.0
5.0
0.5
1.0
2.0
5.0
ΔTSamples [ns]
100
100
100
100
200
200
200
200
50
50
50
50
σt [ns]
2.5
5.5
10.2
39.8
2.8
6.2
12.3
46.5
2.4
4.6
9.7
41.9
}
}
}
Bernd Lewandowski - Ruhr-Universität Bochum - SCINT 2003
5 samples
on rising edge
3 samples
on rising edge
10 samples
on rising edge
29
BGO
• BGO has sufficient light yield
• Timing can be handled by adequate electronics
We will perform further
investigations with BGO
as an option for the Panda Emc
11. 9. 2003
Bernd Lewandowski - Ruhr-Universität Bochum - SCINT 2003
30
Summary & Outlook
R&D tasks
• Improvement of PWO light yield
• Detailed time resolution studies for BGO
• Tests of APD readout
and radiation damage
– Planned this year:
testbeam @ KVI, MAMI
• Development of large
area APDs (100mm2)
by Hamatsu
• Tests of other
Photosensors
11. 9. 2003
Bernd Lewandowski - Ruhr-Universität Bochum - SCINT 2003
31
Panda Collaboration
At present a group of 150 physicists
from 40 institutions of 9 Countries.
Austria - Germany – Italy – Netherlands – Poland – Russia – Sweden – U.K. – U.S.
Bochum, Bonn, Catania, Cracow, Dresden,
Dubna I + II, Edinburg, Erlangen, Ferrara,
Frascati, Genova, Giessen, Glasgow, KVI
Groningen, FZ Jülich I + II, Los Alamos, Mainz,
Milano, TU München, Münster, Northwestern,
BINP Novosibirsk, Pavia, Silesia, Stockolm,
Torino I + II, Torino Politecnico,Trieste, TSL
Uppsala, Tübingen, Uppsala, SINS Warsaw, AAS
Wien
Spokesperson: Ulrich Wiedner - Uppsala
Deputy: Paola Gianotti - LNF
11. 9. 2003
http://www.gsi.de/hesr/panda
Bernd Lewandowski
- Ruhr-Universität Bochum - SCINT 2003
32
Appendix
11. 9. 2003
Bernd Lewandowski - Ruhr-Universität Bochum - SCINT 2003
33
Target
An internal cluster-jet/pellet target is under study:
1016 atoms/cm2 for D=20-40 mm
Pellet target layout
Cluster-jet target layout
11. 9. 2003
Bernd Lewandowski - Ruhr-Universität Bochum - SCINT 2003
34
Vertexing: Micro Vertex Detector
7.2 mio. barrel pixels
50 x 300 μm
pellet/cluster pipe
beam pipe
2 mio. forward pixels
100 x 150 μm
Readout: ASICs (ATLAS/CMS) 0.37% X0
or pixel one side – readout other side (TESLA)
11. 9. 2003
Bernd Lewandowski - Ruhr-Universität Bochum - SCINT 2003
35
Tracking: Straw Tube Tracker
Number of double layers
Skew angle of dbl layers 1 and 15
Skew angle of dbl layers 2-14
15
0o
2o-3o
Straw tube wall thickness
Wire thickness
Gas
Length
Diameter of tubes in
double layers
1-5, 6-10, and 11-15
Number of straw tubes
26 mm
20 mm
90%He
10%C4H10
150 cm
4 mm
6 mm
8 mm
8734
Transverse resolution sx,y
Longitudinal resolution sz
150 mm
1 mm
11. 9. 2003
Bernd Lewandowski - Ruhr-Universität Bochum - SCINT 2003
36
Tracking: Forward MDC
• 6 layers of sense wires in
• 3 double layers (y,u,v)
• not stretched radially
(mass)
• realized at HADES
– high counting rates
– position resolution 70μm
HADES@GSI
11. 9. 2003
Bernd Lewandowski - Ruhr-Universität Bochum - SCINT 2003
37
PID: DIRC (Cherenkov)
BaBar@SLAC
less space than aero gel
costs of calorimeter
no problems with field
11. 9. 2003
Bernd Lewandowski - Ruhr-Universität Bochum - SCINT 2003
38
PID: Forward RICH
Multi pad gas
Detector
Mismatch photons
CsI photon conversion
LHCb
Aerogel
n=1.02
proximity focusing
11. 9. 2003
mirrors
Bernd Lewandowski - Ruhr-Universität Bochum - SCINT 2003
39
APD Hamamatsu S8664-55
5 mm
11. 9. 2003
Bernd Lewandowski - Ruhr-Universität Bochum - SCINT 2003
40
high energy photon detection
3500
20 0
counts / a.u.
low energy proton detection
counts
CeF3
120 0
CeF3
15 0
BaF2
2 x 2 x 14 cm
80 0
3
TAPS geometry
25 cm
10 0
40 0
50
0
0
10
20
30
40
50
60
70
80
90
100
10
20
30
40
50
60
70
80
90
10 0
s
Eg = 55 MeV
E
227 MeV
480 MeV
3000
2500

2.17 %
+ 2.70%
E[GeV ]
2000
experiment
1500
769 MeV
15 0
PbWO4
10 0
2 x 2 x 15 cm
80
3
PbWO4:Mo
1000
GEANT
3
1.5 x 1.5 x 1.5 cm
500
40
50
0
0
0
0
10
20
30
40
50
60
70
80
90
10 0
10
20
30
40
50
60
70
80
90
10 0
proton energy / MeV
85 MeV p + C @ KVI
good resolution for protons
due to:
• high light output
• localized energy deposition
general applicability proven !
11. 9. 2003
200
400
600
800
energy / MeV
1000
@MZ
R. Novotny et al., II. Phys. Inst. GI
in collaboration with Korth-Kristalle GmbH
limited resolution for photons
due to:
• imperfection of crystals
• insufficient size
in spite of high luminescence yield
Bernd Lewandowski - Ruhr-Universität Bochum - SCINT 2003
41
CeF3
• CeF3 needs further R&D to improve
resolution for photons
• Rel. long X0
 compact design not possible (compared to PWO)
• Constraints from target
may limit the available space for the EMC
 CeF3 is not an option for the barrel part
11. 9. 2003
Bernd Lewandowski - Ruhr-Universität Bochum - SCINT 2003
42
BGO: event rates
• Max. occupancy of one crystal
due to bkgr simulations:
2% · 107 events/s = 2·105 s-1
• Use digital tail cancelation in the
feature extraction
• conservative scaling of the
rise time
– CsI: 100 ns / 940 ns
– BGO: 12 ns / 200 ns
• Rate we can handle: ( 2·trise· 10 )-1 = 2.5·105 events/s
11. 9. 2003
Bernd Lewandowski - Ruhr-Universität Bochum - SCINT 2003
43
Why Antiprotons?
•high resolution spectroscopy with
p-beams in formation experiments:
 DE  DEbeam
•high yields in pp of gluonic excitations
– glueballs, hybrids
•event tagging by pair wise associated production,
– (particle, anti-particle) e.g. ppXXbar
•large √s at low momentum transfer
– important for in-medium "implantation" of hadrons:
– study of in-medium effects
11. 9. 2003
Bernd Lewandowski - Ruhr-Universität Bochum - SCINT 2003
44
Timeline
•since 1996
Discussion about GSI future
International workshops, reviews, accelerator R&D
•May 1999
Letter of Intend for an antiproton facility
(40 authors) Studies for detector concept
•Jan. 2001
Detector simulation with GEANT4
•Nov. 2001
Conceptual Design Report
of an „International Accelerator Facility for
Beams of Ions and Antiprotons”
•Nov. 2001
Review by an international review committee
of the „Deutscher Wissenschaftsrat“
•April 2002 International p-Workshop at GSI
•July 2002
Positive Votum by the „Deutscher Wissenschaftsrat“
•Feb. 5, 2003 Positive Decision by the „bmb+f”
11. 9. 2003
Bernd Lewandowski - Ruhr-Universität Bochum - SCINT 2003
45
Resonance Scan
Resonance
Cross
Section
Measured
Rate
Beam
Profile
ECM
small and well controlled
beam momentum spread
Dp/p
is extremely important
11. 9. 2003
Bernd Lewandowski - Ruhr-Universität Bochum - SCINT 2003
46