Results from first beam tests for the development of a RICH detector for CBM J. Eschke 1*, C. Höhne 1 for the CBM collaboration 1 GSI, Darmstadt, Germany tracking, momentum determination, vertex reconstruction: radiation hard silicon pixel/strip detectors (MVD+STS) in a magnetic dipole field hadron ID: TOF (& RICH) electron ID: RICH & TRD & TOF photons, π 0, η: ECAL PSD for event characterization high speed DAQ and trigger → rare probes! RICH TRD ECAL Magnet STS + MVD PSD * Layout of the CBM experiment (e + e - set up) TOF RICH concept Front End Electronics and DAQ/Event Building for CBM requirements FEE event rate up to 10 MHz, max. several 100k hits/channel/s sufficient time resolution for event assignment and separation of uncorrelated background plan for RICH FEE: synergy with CBM developments: use future “TRD-XYter”  test concept with currently available n-XYter-Front End Board n-XYTER readout ASIC adopt to readout for photomultipliers: need to attenuate PMT gain before MAPMT signal ~ 10 6 electrons  attenuation by factor ~50 required Proximity focusing setup with plexiglass radiator Front End Electronic Simulation Test beam set up at GSI Sept self triggered – all events no cut on timing time difference: beam counter coincidence – MAPMT hit ADC value (reversed scale) with cut on time difference (beam events) Test beam results – 8 mm plexiglass radiator example ADC spectra of one channel event integrated distribution of MAPMT hits  clear ¼ Cherenkov ring image single event very good noise suppression by timing cut (no other cuts applied)  clean signal Number of MAPMT hits / beam event mean Number of MAPMT hits per event ~ 3.5  single photon counting σ FEE <3,7 ns Conclusions New self triggered test chip on front end board successfully adopted for readout of MAPMTs  Low background noise level achieved by timing cut on beam events. Good time resolution of FEE essential for clean signal and noise reduction, here σ FEE <3,7 ns. Number of detected hits in the MAPMT is consistent with expectations  Single photon counting! Outlook: Further characterization of MAPMT with LED test setup in lab: - crosstalk between channels - performance with WLS coverage for enhanced UV-sensitivity ( additional crosstalk tolerable?) Further development of readout chain: - first version of CBM-XYter (gas detector branch) available soon (adopt to MAPMT readout) Plan for complete RICH prototype with 16 (or 9) MAPMTs and mirror prototype Comparison of measured number of photons to expectation Produced number of Cherenkov photons in the wavelength interval nm for 2.78 GeV/c proton in 8 mm plexiglass is: Characterictics H8500 MAPMTs Reduction of measured photons due to - geometry: less than ¼ sequement: ~¼ * 64/100 - light transmission in plexiglas: ~ 80% - Quantuum efficiency weighted with yield of produced photons per ∆Eν: ~15% - assumed photon collection efficiency: ~ 80% N photons expected = , N MAPMThits measured = 3.5 σ 2 =σ 2 FEE +σ 2 MAPMT +σ 2 BeamCoincPMTs Observables sensitive to high  B / phase transition: ρ, ω, Φ-mesons, J/Ψ, Ψ‘ leptonic decay → e+e- Compressed Baryonic FAIR – high  B, moderate T: searching for the landmarks of the QCD phase diagram first order deconfinement phase transition chiral phase transition (high baryon densities!) QCD critical endpoint in A+A collisions from 2-45 AGeV starting in 2017 (CBM + HADES) at SIS100 and SIS300 task clean electron identification for p ≤ 8-10 GeV/c π-suppression factor ~ , 10 4 if combined with TRD large acceptance (± 25°), good efficiency (~20 hits/ring) challenges high track density: central Au+Au collisions, 25 AGeV: ~600 charged tracks RICH detector positioned behind STS, Magnet material budget: large number of secondary electrons → high ring & track density in RICH detector: typical scale: ~100 rings: 30 π, 60 2nd e±, 5-10 e± from target → fake rings, wrong ring-track matches interaction rates up to 10 MHz (J/Ψ) gaseous RICH detector (~1.7 m radiator length) rather high Cherenkov threshold for pions → CO 2 radiator (γ th =33, p π,th =4.65 GeV/c) glass mirrors (3-6 mm, R=3m, size 11.8 m 2 ) photodetector plane (2.4 m 2 ) : Multi-Anode PMTs → 860 MAPMTs with 64 channels/piece 55k channels in total → investigation of H8500 MAPMT series from Hamamatsu pedestal (noise) peak example: 236 Ref: Hamamatsu Photonics K.K. (data push architecture) fast self-triggered FEE for CBM  No Trigger, front-end has to detect all valid hits autonomously  CBM is a fixed-target experiment, thus no bunch crossing clock, interactions occur at random times  Use timestamps to organize and correlate data  Ship all hits, tagged with a timestamp, to subsequent data buffer and processing stages.  Typical parameters (for 10 7 interactions/sec and 1% occupancy): 100 kHz channel hit rate 600 kbyte/sec per channel data flow 100 Mbyte/sec data flow for a 128 channel ASIC Requirements Front End Electronics for the CBM-RICH detector event rate up to 10 MHz, max. ~250k hits/channel/s sufficient time resolution (of a few ns for separation of uncorrelated background) Architecture of a single n-XYTER channel Key parameters of the n-XYTER chip:  Self-triggered architecture channels - developed for Silicon detectors (125k electrons dynamical range)  Positive and negative front-end polarity.  32 MHz readout frequency  1 ns timestamp binning *Developed within DETNI EU project, A.S. Brogna et al., NIM A 568 (2006) 301 Front End Electronics for the CBM-RICH detector CBM Front End Electronics development From n-XYTER to CBM-XYTER –ASICs for Silicon Strip and Gas Detector Readout fast self-triggered FEE: “n-XYter” chip developed for Si-detectors (dynamical range up to -125∙10 3 e - ) used as working horse for further developments Proximity focusing set up: 2.8 GeV/c Proton Beam at GSI (Sept. 2009) Radiator: 8 mm plexiglass (tilted by 45 o )  Cherenkov angle ~ 45 o  ¼ Cherenkov ring image expected (simulation) noise reduction! An attenuator board has been designed, simulated and tested for the attenuation of MAPMT signals (division factor 1/48). Beam test at GSI September 2009  test FEE concept for CBM-RICH photo detector read out (MAPMTs) under beam conditions Data taking with new self triggered FEE Front End Board (FEB) Read Out Controller (ROC) together with other detector prototypes, beam counters and common DAQ (DABC) H total refection of Cherenkov light if not tilted  test performance of MAPMT H with Cherenkov photons =3.5