cbm @gsi march 2006r. gernhäuser (tu-münchen) the hades experiment geometry: full azimuth, polar...
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CBM @GSI March 2006
R. Gernhäuser (TU-München)
The HADES ExperimentThe HADES Experiment
Geometry:Full azimuth , polar angles 18o - 85o
Pair acceptance ~ 0.35
Momentum reconstruction:Ilse: super-conducting toroid, B=0.7 TmMDC: Multi-wire drift chamber y~100 mm
CBM @GSI March 2006
R. Gernhäuser (TU-München)
• e+/e- identification• LVL2 trigger device• hadron blind• medium size (1.5 m)• low radiation length
HADES RICH SetupHADES RICH Setup
CBM @GSI March 2006
R. Gernhäuser (TU-München)
Design ConstraintsDesign ConstraintsAcceptance Geometry :
Dmirr = 1440 mm
Rcurv = 881 mm 360mm < Lrad < 710mm
Background Radiation length :
(x/X0) target + (x/X0)radiator
+ (x/X0)CFK shell + (x/X0)mirror < 2-3 %
min. support structure, d ~ 3 kg / m2
Sensitivity Photon detection : mirror reflectivity R (150 nm) > 70%
VUV transmission of radiator and window
photon conversion (CsI)
Rate capability 105/s central collisions
CBM @GSI March 2006
R. Gernhäuser (TU-München)
Photon detector
CBM @GSI March 2006
R. Gernhäuser (TU-München)
Fast Gaseous Photon DetectorFast Gaseous Photon Detector
Pad cathode
Anode w ires 20 m
Cathode w ires 50 m
G ate w ires 20 m
2 ,4m m
3,0m m
7,0m m
6,6m m
1,65m m
3,3m m
U =+2,5 kVanod
U =0Vcath
U =500Vgate
U =0Vpcath
e-
UV
Ph
oto
n
PC B
CsI+RSGconnector
CH 4
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)
CBM @GSI March 2006
R. Gernhäuser (TU-München)
Photon Detector ShapePhoton Detector Shape
– 4712 pads/sector, individually shaped
4.5 mm < y < 7 mm, x = 6.6mm– GASSIPLEX based FE-electronics
– 10s total conversion time
rin
g r
adiu
s [p
ads]
polar angle [°]
A trigger device for ~ 1 particles
constant ring radius
CBM @GSI March 2006
R. Gernhäuser (TU-München)
VUV Mirror
CBM @GSI March 2006
R. Gernhäuser (TU-München)
Sigradur® raw substrate fromHTW GmbH, D-86672 Thierhaupten
500 mm
d = 4 mm
Sigradur® (Zeit. Werkstofftech. 15, (1984) 331)
pure Carbon :
density = 1.4 - 1.5 [g/cm3]
hardness = 230 - 340 [HV]
stiffness = 260 - 210 [MPa]
E – Mod. = 35 [GPa] X0 = 28 cm ; d = 2 mm : x/X0 < 0. 8%
Glassy CarbonGlassy Carbon
d = 2 mm
CBM @GSI March 2006
R. Gernhäuser (TU-München)
Cutting & MachiningCutting & Machining
1st try
Cumbersome procedure• break throughs : catastr. + progress
After a while ( ~ 3 years):
Succesfull machining of 18 panels
No (!!!)coating
3rd try
CBM @GSI March 2006
R. Gernhäuser (TU-München)
Float Glass SectorsFloat Glass Sectors
• Glass float glass oulded by FLABEG GmbH6 panels, molded
X0 = 14 cm ; d = 1.8 mm :
x/X0 ~ 2%
R = 881 mm
CBM @GSI March 2006
R. Gernhäuser (TU-München)
Support StrucureSupport Strucure
Carbon 4 sect. Glass upstream downstream view
CBM @GSI March 2006
R. Gernhäuser (TU-München)
VUV ReflectivitiesVUV Reflectivities
J. Friese, TU München
Measurements on smallsamples (from cutting) :
after ´finish´ & opt. coating
1 – 2 nmR ~ 82 % @ = 150 nm
before ´finish´
3 – 4 nmR ~ 65 % @ = 150 nm
No ageing for 1 year
RICH 2002
CarbonGlass
= 1 nm = 2 nm = 3 nm
Carbon after
1 month 4 months 15 months
= 3 nm
*
CBM @GSI March 2006
R. Gernhäuser (TU-München)
CaF2 Window
CBM @GSI March 2006
R. Gernhäuser (TU-München)
WindowWindow
Crystal window Ø = 140cm
64 CaF2 hexagonal crystals
Ø = 20cm,
d = 5mm p < 5mbar
CBM @GSI March 2006
R. Gernhäuser (TU-München)
The Eye of HADESThe Eye of HADES
HADES RICH:
28272 pads @105 samples / sec.
3 G pix/s
400m Carbon fiber
radiator shell
CBM @GSI March 2006
R. Gernhäuser (TU-München)
1
0.8
0.6
0.4
0.2
0.0
120 140 160 180 200 220
SiO2
MgF2
Tra
nsm
issi
on
[nm]
pad plane
tank
window
mirror
tank shell
target
radiator gas
detector gas
beam
field plane
photon detector
Efficiency calibrationEfficiency calibration (OEM)(OEM)
beam
Radiation of Cherenkov-Photonsin SiO2 and MgF2 discs.Beam: 12C @ 600AMeV, = 0.794
CBM @GSI March 2006
R. Gernhäuser (TU-München)
OEM RadiatorOEM Radiator
2cm
beam
beam line
CBM @GSI March 2006
R. Gernhäuser (TU-München)
beam pipe shadow
Nph ~ N0 * Z2
500 evt accumulated
MgF2
SiO2
Detector Response Detector Response
1 evt
C12 ions, E = 600 AMeV
CBM @GSI March 2006
R. Gernhäuser (TU-München)
Detection efficiency for photonsDetection efficiency for photons
Sec 1
MgF2/ SiO2
Sec 2
MgF2 / SiO2
Sec 3
MgF2/ SiO2
Sec 4
MgF2 / SiO2
Sec 5
MgF2/ SiO2
Sec 6
MgF2 / SiO2
N0Sim 109 109 109 109 109 109
N0Exp 68 / 74 70 / 72 70 / 85 71 /89 71 / 86 73 / 77
CBM @GSI March 2006
R. Gernhäuser (TU-München)
Ring propertiesfor e+/e-
from target
CBM @GSI March 2006
R. Gernhäuser (TU-München)
Measured RICH Rings Measured RICH Rings
C + CE = 1 AGeV
-Dalitz decay leptons ?!
Ring recognition:
Pattern Matrix
Hough-Transf.
CBM @GSI March 2006
R. Gernhäuser (TU-München)
Ring QualityRing Quality
Pattern Matrix Quality
e+/- induced rings
noise induced rings
Co
un
ts Distribution of Pattern Matrix Quality
–No significant differences between sectors–no variation with time since (1999)–low efficient area < 5%–Gas detector sensitive to high rates
+
--
++
of 13 x 13 individual weights
derived from simulation
CBM @GSI March 2006
R. Gernhäuser (TU-München)
Ring propertiesRing properties
Charge/ring [a.u.] Pads/ring
Co
un
ts [
a.u
.]
Co
un
t s [
a.u
.]C
ou
nt s
[a
.u.]
Co
un
t s [
a.u
.]
SimExp
Charge per ring Pads per ring
single
double
C + CE = 1A GeV
single
double
ee++
ee--
ee++
ee--
CBM @GSI March 2006
R. Gernhäuser (TU-München)
Ring propertiesRing properties
Single rings
Double rings
Pads per ring
pol angle deg]
Pad
s /ri
ng
Pad
s /ri
ng
SimExp
pol angle [deg]
c ha r
ge /
rin
g [
a.u
. ]c h
a rg
e /ri
ng
[a.
u. ]
Charge per ring
ee++ee--
ee++ ee--
CBM @GSI March 2006
R. Gernhäuser (TU-München)
Lepton ID with TOF and Lepton ID with TOF and RICHRICH
e- e+
log. z axis !
p*q [MeV/c]
v/c
1
10
102
d
p
e- e+
+
A+KCl @ 2 AGeV
v/c
CBM @GSI March 2006
R. Gernhäuser (TU-München)
The Background ProblemThe Background Problem
CBM @GSI March 2006
R. Gernhäuser (TU-München)
Online Lepton IDOnline Lepton ID
• Fast readout of all PID - detectors (10s)
• Real time processing with– Calibration
– Pattern recognition
– Position calculation
• Transfer to Matching Unit• Decision and second level
trigger distribution
Matching UnitSecond Level
Trigger
TOFShowerRICH
Data reduction from
4 Gbyte/s to 10MBytes/s
Hadron blind device
CBM @GSI March 2006
R. Gernhäuser (TU-München)
RICH online Lepton ID RICH online Lepton ID
• Ring recognition algorithm (fixed radius)– Ring radius (+) inner and outer veto regions (-)
– Correlation of pads
– Summing correlation results
– Threshold on positive and negative quality parameters
Typical Algorithm
CBM @GSI March 2006
R. Gernhäuser (TU-München)
Pulse height analysis Pulse height analysis
* CERN / LHCC 98-19 ALICE TDR 1
anode voltage [V]
Qmean
[a.u.] All Clusters
Calculation Class 1 Cluster
Charge [ADC chan.]
Cou
nts
Class 1* Class 2 Class 3
1 ADC chan. = 1730 e-
U = 2450 V
QMean @ 2450 V = 5 * 104 e-
CBM @GSI March 2006
R. Gernhäuser (TU-München)
Cluster AnalysisCluster Analysis
Simulation
Experiment
Parametrisation for simulation
CBM @GSI March 2006
R. Gernhäuser (TU-München)
Charge & pad distributionsCharge & pad distributions
Charge [ADC chan.] Pad mult.
Cou
nts
Simulation
Experiment
CBM @GSI March 2006
R. Gernhäuser (TU-München)
Lepton ID Software and Lepton ID Software and HardwareHardware
Efficiency of Ring recognition using matrix method @ suppression 100
Data from GEANT simulation
Correlation of rings found by hardware or software image
processing (experiment)
[100%]