Transcript HADES High Acceptance Di

The HADES RICH
High Acceptance Di-Electron Spectrometer
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The HADES Spectrometer
Special requirements
RICH setup
– Mirror
– Window
– Photon detector
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Preliminary results from
12C-12C [1.0 AGeV]
Outlook
For the HADES Collaboration
R. Gernhäuser (TU-München)
RICH 2002 @ Pylos
Motivation
 Properties of hadrons
in strong int. matter: M, G vs r, mB, T, V
Vector meson r, ,  spectral functions measurements
 Hadron’s structure: VDM, Form factors, vector meson-nucleon inter.
Dalitz and two-body decays, pN, pN reactions
SIS / GSI : heavy ion, proton,pion beams
0  r  3 r0 0  T  80 MeV
HADES: systematic dilepton spectroscopy
• meson prod. in pA / pA :
• meson prod. in pp / pp :
• meson prod. in AA
:
R. Gernhäuser (TU-München)
r = r0 ,
T = 0 MeV
r=0,
T = 0 MeV
r = 1-3r0 , T = 80 MeV
RICH 2002 @ Pylos
High Acceptance Di-Electron Spectrometer
Magnet
SC. toroid ( 6 coils)
2p in 
18o < J < 85o
Lepton Identification
RICH
C4F10 + gas Phot. Det.
CsI - cathode
META TOF scintillator wall +
Pre-Shower detector
p/p identification
META and tracking
Tracking
p – measurement, vertex
reconstruction
MDC Drift chambers dx ~ 80 mm (s)
R. Gernhäuser (TU-München)
RICH 2002 @ Pylos
Design Constraints
Meson
Mass
G (MeV/c2)
dominant
decay
Ge+e-/G
(MeV/c2)
r
769
150
2p
4.5 10-5

783
8.5
2p
7.1 10-5

1019
4.5
2K
2.9 10-4
beam intensity
108/s
central collisions 105/s
ch. particles
< 200/evt
lepton pairs
103/s
experiment hall
lrad ~ 40 cm
Trigger device
R. Gernhäuser (TU-München)
fast
high granularity
hadron blind
CsI based MWPC
N0 ~ 100
 thr  10 ;
with gas radiator
N det  N 0  lrad 
1
thr
2
RICH 2002 @ Pylos
 10
Fast Photon Detector
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
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Ugate=500V
Gate wires 20mm
Cathode wires 50mm
UV Photon
6 sector shaped MWPCs with 2.4 mm gap
5*104 < gain < 1*105 @ 2450V
signal coupling on several pads
solid CsI photon converter on special
substrate material (RSG)
Ucath=0V
Anode wires 20mm
Uanod=+2,5 kV
CH4
7,0mm
3,0mm
e-
2,4mm
Upcath=0V
1,65mm
CsI+RSG
Pad cathode
connector
6,6mm
3,3mm
PCB
R. Gernhäuser (TU-München)
RICH 2002 @ Pylos
Photon Detector Shape
A trigger device for b ~ 1 particles
constant ring radius
– 4712 pads/sector, individually shaped
4.5 mm < y < 7 mm, x = 6.6mm
– GASSIPLEX based FE-electronics
ring radius [pads]
– 10ms conversion time
polar angle [°]
R. Gernhäuser (TU-München)
RICH 2002 @ Pylos
Mirror
Ø 150 cm, R = 871 mm, d = 2 mm
Poly – Carbon
–rad. length X0 = 28cm
–18 panels polished
Float Glass
–rad. length X0 = 14cm
–6 panels, molded
J. Friese (Saturday afternoon)
R. Gernhäuser (TU-München)
RICH 2002 @ Pylos
CaF2 - Window
Crystal window Ø = 140cm
64 CaF2 hexagonal crystals
Ø = 20cm,
d = 5mm Dp < 5mbar
R. Gernhäuser (TU-München)
RICH 2002 @ Pylos
The Eye of HADES
Commissioning in 2001
Full HADES Setup (! outer tracking)
108 events C – C 1-2 AGeV
400mm Carbon fiber
radiator shell
R. Gernhäuser (TU-München)
RICH 2002 @ Pylos
Typical Pattern
Data Nov. 2001, C - C @ E = 1 AGeV
R. Gernhäuser (TU-München)
RICH 2002 @ Pylos
RICH online Lepton ID
• Ring recognition algorithm (fixed radius)
– Ring radius (+) inner and outer veto
regions (-)
– Threshold on positive and negative
quality parameters
J. Lehnert (Sunday morning)
Typical Algorithm
Reference of qualitative and quantitative
detector response needed
R. Gernhäuser (TU-München)
RICH 2002 @ Pylos
Calibration Measurement
(OEM online efficiency measurement)
tank
detector gas
window
pad plane
field plane
mirror
calibrated light source!
Photons produced by 600 AMeV
12C beam particles passing two
different solid radiators
tank shell
photon detector
beam
target
beam
radiator gas
R. Gernhäuser (TU-München)
RICH 2002 @ Pylos
OEM results
Radial distribution of photons represents
spectral sensitivity of the detector
163 nm
200 nm
145 nm
200 nm
single 12C hit
N0 > 90
beam pipe shadow
R. Gernhäuser (TU-München)
L. Fabbietti (Sunday morning)
RICH 2002 @ Pylos
Dominant Dilepton Sources
7 M events C+C @1.0 AGeV

p0
Dalitz

Conversion
e+
ee+
e-
R. Gernhäuser (TU-München)
opening angle [°]
cut on opening angle
combinatory pairs negligible
RICH 2002 @ Pylos
The Ring Properties
Rings from single leptons
e+e- pair with 1 track/ring
polar angle [°]
Efficiency of Ring recognition
momentum [MeV/c]
Th. Eberl (Sunday afternoon)
R. Gernhäuser (TU-München)
RICH 2002 @ Pylos
q*momentum
Lepton ID with TOF and RICH
Data: Nov01
C-C 2.0 AGeV
q*momentum
p
TOF[ns]
R. Gernhäuser (TU-München)
RICH 2002 @ Pylos
Lepton ID online - offline
Full HADES simulation
and data analysis
RQMD ev.generator
Correlation of rings found by
hardware or software image
processing
A. Toia (Sunday morning)
R. Gernhäuserq*
(TU-München)
momentum
[e*MeV/c]
RICH 2002 @ Pylos
Outlook
•HADES comes into operation
(e/p/p sep., LVL2 trig., tracking)
•3 MDC layer will be completed this summer (dp3% for r/)
Phase I (2002 – 2003) :
(acc. proposals S200 ,S262)
Continuum below M inv < 600 MeV/c2 ; p0 Dalitz in C+C (more statistics)
High statistics e+,e- production in HI reactions C+ C @ 1 – 2 AGeV
(compare to DLS)
e+e- production in p- p
p- p
@ 0.8 – 1.3 GeV/c
(below and above threshold for r/)
 e+e- pair acceptances
R. Gernhäuser (TU-München)
pp  pp h  pp e+eRICH 2002 @ Pylos