March 2006R. Gernhäuser (TU-München) The HADES Experiment Geometry: Full azimuth, polar angles 18 o - 85 o Pair acceptance ~ 0.35 Momentum reconstruction: Ilse: super-conducting toroid, B  =0.7 Tm MDC: Multi-wire drift chamber  y ~100 mm

March 2006R. Gernhäuser (TU-München) e + /e - identification LVL2 trigger device hadron blind medium size (1.5 m) low radiation length HADES RICH Setup

March 2006R. Gernhäuser (TU-München) Design Constraints Acceptance  Geometry : D mirr = 1440 mm R curv = 881 mm  360mm < L rad < 710mm Background  Radiation length : ( x/X 0 ) target + ( x/X 0 ) radiator + ( x/X 0 ) CFK shell + ( x/X 0 ) mirror < 2-3 %  min. support structure,  d ~ 3 kg / m 2 Sensitivity  Photon detection :  mirror reflectivity R (150 nm) > 70%  VUV transmission of radiator and window  photon conversion (CsI) Rate capability  10 5 /s central collisions

March 2006R. Gernhäuser (TU-München) Photon detector

March 2006R. Gernhäuser (TU-München) Fast Gaseous Photon Detector  6 sector shaped MWPCs with 2.4 mm gap  5*10 4 < gain < 1* V  signal coupling on several pads  solid CsI photon converter on special substrate material (RSG)

March 2006R. Gernhäuser (TU-München) Photon Detector Shape – 4712 pads/sector, individually shaped 4.5 mm < y < 7 mm, x = 6.6mm – GASSIPLEX based FE-electronics – 10  s total conversion time ring radius [pads] polar angle [°] A trigger device for  ~ 1 particles constant ring radius

March 2006R. Gernhäuser (TU-München) VUV Mirror

March 2006R. Gernhäuser (TU-München) Sigradur ® raw substrate from HTW GmbH, D Thierhaupten 500 mm d = 4 mm Sigradur ® (Zeit. Werkstofftech. 15, (1984) 331) pure Carbon : density  = [g/cm 3 ] hardness = [HV] stiffness = [MPa] E – Mod. = 35 [GPa]  X 0 = 28 cm ; d = 2 mm : x/X 0 < 0. 8% Glassy Carbon d = 2 mm

March 2006R. Gernhäuser (TU-München) Cutting & Machining 1 st try Cumbersome procedure break throughs : catastr. + progress After a while ( ~ 3 years): Succesfull machining of 18 panels No (!!!) coating 3 rd try

March 2006R. Gernhäuser (TU-München) Float Glass Sectors Glass float glass oulded by FLABEG GmbH 6 panels, molded  X 0 = 14 cm ; d = 1.8 mm :  x/X 0 ~ 2%  R = 881 mm

March 2006R. Gernhäuser (TU-München) Support Strucure Carbon 4 sect. Glass upstream downstream view

March 2006R. Gernhäuser (TU-München) VUV Reflectivities J. Friese, TU München Measurements on small samples (from cutting) : after ´finish´ & opt. coating  1 – 2 nm R ~ 82 = 150 nm before ´finish´  3 – 4 nm R ~ 65 = 150 nm No ageing for 1 year RICH 2002 Carbon Glass  = 1 nm  = 2 nm  = 3 nm Carbon after 1 month 4 months 15 months  = 3 nm *

March 2006R. Gernhäuser (TU-München) CaF 2 Window

March 2006R. Gernhäuser (TU-München) Window Crystal window Ø = 140cm 64 CaF 2 hexagonal crystals Ø = 20cm, d = 5mm  p < 5mbar

March 2006R. Gernhäuser (TU-München) The Eye of HADES HADES RICH: samples / sec. 3 G pix/s 400  m Carbon fiber radiator shell

March 2006R. Gernhäuser (TU-München) SiO 2 MgF 2 Transmission [nm] Efficiency calibration (OEM) Radiation of Cherenkov-Photons in SiO 2 and MgF 2 discs. Beam: AMeV,  = 0.794

March 2006R. Gernhäuser (TU-München) OEM Radiator 2cm beam beam line

March 2006R. Gernhäuser (TU-München) beam pipe shadow N ph ~ N0 * Z evt accumulated MgF 2 SiO 2 Detector Response 1 evt C 12 ions, E = 600 AMeV

March 2006R. Gernhäuser (TU-München) Detection efficiency for photons Sec 1 MgF 2 / SiO 2 Sec 2 MgF 2 / SiO 2 Sec 3 MgF 2 / SiO 2 Sec 4 MgF 2 / SiO 2 Sec 5 MgF 2 / SiO 2 Sec 6 MgF 2 / SiO 2 N 0 Sim 109 N 0 Exp 68 / 7470 / 7270 / 8571 /8971 / 8673 / 77

March 2006R. Gernhäuser (TU-München) Ring properties for e + /e - from target

March 2006R. Gernhäuser (TU-München) Measured RICH Rings C + C E = 1 AGeV   -Dalitz decay leptons ?! Ring recognition: Pattern Matrix Hough-Transf.

March 2006R. Gernhäuser (TU-München) Simulated RICH Rings C + C E = 1A GeV Full scale GEANT simulation of the HADES RICH Rings for   - Dalitz leptons based on measured material and optical properties

March 2006R. Gernhäuser (TU-München) Ring Quality Pattern Matrix Quality e +/- induced rings noise induced rings Counts 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

March 2006R. Gernhäuser (TU-München) Ring properties Charge/ring [a.u.] Pads/ring Counts [a.u.] Sim Exp Charge per ringPads per ring single double C + C E = 1A GeV single double e+e+e+e+ e-e-e-e- e+e+e+e+ e-e-e-e-

March 2006R. Gernhäuser (TU-München) Ring properties Single rings Double rings Pads per ring pol angle deg] Pads/ring Sim Exp pol angle [deg] charge/ring [a.u.] Charge per ring e+e+e+e+ e-e-e-e- e+e+e+e+ e-e-e-e-

March 2006R. Gernhäuser (TU-München) Lepton ID with TOF and RICH –– e-e- e+e+ log. z axis ! p*q [MeV/c] v/c d p e-e- e+e+  ++ 2 AGeV v/c

March 2006R. Gernhäuser (TU-München) The Background Problem

March 2006R. Gernhäuser (TU-München) Online Lepton ID Fast readout of all PID - detectors (10  s) Real time processing with –Calibration –Pattern recognition –Position calculation Transfer to Matching Unit Decision and second level trigger distribution Matching Unit Second Level Trigger TOFShowerRICH Data reduction from 4 Gbyte/s to 10MBytes/s Hadron blind device

March 2006R. Gernhäuser (TU-München) 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

March 2006R. Gernhäuser (TU-München) Pulse height analysis * CERN / LHCC ALICE TDR 1 anode voltage [V] Q mean [a.u.] All Clusters Calculation Class 1 Cluster Charge [ADC chan.] Counts Class 1*Class 2Class 3 1 ADC chan. = 1730 e - U = 2450 V Q 2450 V = 5 * 10 4 e -

March 2006R. Gernhäuser (TU-München) Cluster Analysis Simulation Experiment Parametrisation for simulation

March 2006R. Gernhäuser (TU-München) Charge & pad distributions Charge [ADC chan.]Pad mult. Counts Simulation Experiment

March 2006R. Gernhäuser (TU-München) Lepton ID Software and Hardware Efficiency of Ring recognition using matrix suppression 100 Data from GEANT simulation Correlation of rings found by hardware or software image processing (experiment) [100%]

March 2006R. Gernhäuser (TU-München) Single events in the RICH

March 2006R. Gernhäuser (TU-München) Dilepton Sources  e+e+ e-e- Conversion e+e+ e-e- 00  Dalitz 5 M events AGeV

March 2006R. Gernhäuser (TU-München) The Ring Properties Rings from single leptons e + e - pair with 1 track/ring

March 2006R. Gernhäuser (TU-München) Radiator Gas CH 4 and C 4 H 10 mixtures seem to be possible ( detected photons per ring) everything else has to be investigated in an open system

March 2006R. Gernhäuser (TU-München) Frontend Electronics Analog 4 x GASSIPLEX: 4 x 16 channels peaking time 600 ns maximum clock frequency 2Mhz noise < 1000 e- ENC input range 290fC power consumption 19mW/ch Digital AD conversion 8 MHz runtime zero suppression FIFO pipeline standard TTL logic programmable  trigger rate limited to 100kHz