CBM @GSI March 2006R. Gernhäuser (TU-München) The HADES Experiment Geometry: Full azimuth, polar angles 18 o - 85 o Pair acceptance ~ 0.35 Momentum reconstruction:

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


• 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


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


Photon detector

CBM @GSI March 2006


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


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


VUV Mirror

CBM @GSI March 2006


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


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


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


Support StrucureSupport Strucure

Carbon 4 sect. Glass upstream downstream view

CBM @GSI March 2006


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


CaF2 Window

CBM @GSI March 2006


WindowWindow

Crystal window Ø = 140cm

64 CaF2 hexagonal crystals

Ø = 20cm,

d = 5mm p < 5mbar

CBM @GSI March 2006


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


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


OEM RadiatorOEM Radiator

2cm

beam

beam line

CBM @GSI March 2006


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


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


Ring propertiesfor e+/e-

from target

CBM @GSI March 2006


Measured RICH Rings Measured RICH Rings

C + CE = 1 AGeV

-Dalitz decay leptons ?!

Ring recognition:

Pattern Matrix

Hough-Transf.

CBM @GSI March 2006


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


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


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


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


The Background ProblemThe Background Problem

CBM @GSI March 2006


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


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


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


Cluster AnalysisCluster Analysis

Simulation

Experiment

Parametrisation for simulation

CBM @GSI March 2006


Charge & pad distributionsCharge & pad distributions

Charge [ADC chan.] Pad mult.

Cou

nts

Simulation

Experiment

CBM @GSI March 2006


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%]

Documents

CBM @GSI March 2006R. Gernhäuser (TU-München) The HADES Experiment Geometry: Full azimuth, polar angles 18 o - 85 o Pair acceptance ~ 0.35 Momentum reconstruction: