Hans Rudolf Schmidt GSI Darmstadt The CBM-GEM project for FAIR mainly: Muon Chamber R&D in India (talk of Anand Kumar Dubey, VECC group Kolkata) Hans Rudolf Schmidt GSI Darmstadt RD51 Collaboration Meeting 25. May 2010

CBM @ FAIR CBM at SIS 100 (start version/30 GeV/c (protons) and SIS 300 (future/90 GeV/c) systematic exploration of high baryon density matter in A+A collisions from 4-90×A/Z AGeV/c beam energy explore the QCD phase diagram, chiral symmetry restauration (AGS, SPS, RHIC) very high rate (fixed target) HI-experiments (> 107 interactions/s), access to rare probes (dileptons, (open) charm....) CBM Muon Chambers

The CBM experiment – electron-hadron setup Transition Radiation Detectors Electro- magnetic Calorimeter Ring Imaging Cherenkov Detector Silicon Tracking System Projectile Spectator Detector (Calorimeter) Micro Vertex Detector Resistive Plate Chambers (TOF) Dipole magnet CBM Muon Chambers

The CBM experiment – muon setup Tracking Detector Muon detection System Silicon Tracking System Projectile Spectator Detector (Calorimeter) Micro Vertex Detector Dipole magnet Resistive Plate Chambers (TOF) CBM Muon Chambers

Much Layout Studies in Progess baseline: 6 GEM stations 3 layers per station 30 x 30 cm2 GEM foils other layouts under study In our study we used the compact version of MUCH system consisting of 5 station, each station containing 3 layers. The thickness of the active gas volume was selected at 1cm which is close to realistic case. Three MUCH layer designs were considered in the analysis: the monolithic one, when a layer represents a big monolithic shape segmented by rectangular sectors; and two variants of module design, when each layer consists of modules arranged in rows on both sides of the layer with some overlap region in one dimension. Two values for module size were chosen, namely 25.6x25.6 cm^2 and 51.2x51.2 cm^2. Larger module sizes are restricted for now by construction technology of GEM foils. 35 m2 of GEM stations (300 m2 of foils) #pads: > 500 k pad size: 2.8 mm2 and larger (optimization under scrutiny) CBM Muon Chambers 5 5

Particle Rates/Dose LHC/DESY/FAIR Max. Rates in CBM MUCH beam Neutron fluence in CBM cave (FLUKA –simulation) Typical operation scenario: 6 years  1013 - 1015 neq/cm2  radiation hardness regime of LHC experiments CBM MUCH-GEM 10 MHz/cm2 CBM TRD1 100 kHz/cm2 CBM Muon Chambers

CBM Muon detector requirements: Main issues: The first plane(s) has a high density of tracks -- detector should be able to cope up with high rate. ~ 10 MHz/cm2 good position resolution Should be radiation resistant Large area detector – modular arrangement suitable options: micropattern gas detectors such as GEMs, Micromegas, THGEMs or Straw Tubes institutions: VECC, India: R&D in GEM, THGEM – Design & Construction PNPI, Russia: R&D THGEM, Hybrid Micromegas-GEM – Layout studies VBLHEP, JINR, Russia: Straw Tubes GSI/University of Tübingen: GEM-ageing in high rate hadronic environment CBM Muon Chambers

MUCH R&D @ VECC, KalKota we have assembled and tested double and triple GEM prototypes based on 10 cm x 10 cm GEM foils. Idea is to optimize the operating conditions with 10 cm x 10 cm. In future we would like to go to 30 x 30 cm2 and later to larger dimensions. CBM Muon Chambers

Schematic of prototype GEM chamber assembly Readout PCB GEMS 1 2 3 CERN made GEM foils obtained from Area: 10cm x 10cm Drift gap: ~7mm Induction gap: 1.5mm Transfer gap: 1mm Drift plane (inner side copper plated) 12 x cm 12 cm x 10 mm CBM Muon Chambers

First Test with Fe55 + nXYTER using 3GEM Pulse height from Pad#20 nXYTER Peak ADC baseline (2150) subtraction + “inversion”: Subtracted ( ADC) ADC DeltaV (GEM) CBM Muon Chambers

Testing of GEM chambers @GSI At the SIS 18 beam line using proton beams of 2.5 GeV/c Aim being : -- to test the response of the detector to charged particles. -- efficiency, cluster size, gain uniformity, rate capability -- testing with actual electronics for CBM : nXYTER -- testing with the actual DAQ -- Aug08-- first successful test with n-XYTER(with 64 channels bonded ) + GEM was performed. MIP spectra for 2GEMs and 3 GEMs were obtained. -- Aug-Sep 09, In 2009 a fuller version of nXYTER with all the 128 channels bonded was available. This offered a better configuration for efficiency estimation and also for cluster size estimation. CBM Muon Chambers

Readout Board for Test beam Aug-Sep 09 Two triple GEM chambers were fabricated : det 01 – with two different pad sizes(shown below) det02 -- same size pads but with larger induction gap Inside view Outside view Inside view CBM Muon Chambers

GEM chambers – Beamtest 2009 CBM Muon Chambers

Aug-Sep09 test (with 2.3 GeV/c protons) pulse height spectra Correlation between GEM1 and GEM2 CBM Muon Chambers

ADC distribution of main cell and variation with HV 4 fold increase in ADC for a deltaV(GEM) increase by 50V CBM Muon Chambers

Efficiency Measurments (with beam) effciency too small (<70%) and time dependant... possible reasons under investigation (extraction method, electronics, readout, etc) CBM Muon Chambers

Cosmic Ray test setup at VECC Setup for detector efficiency: 1. Detector+Ortec preamp+amp Using MANAS coupled to PCI CFD card 3. Using Aux + nXYTER CBM Muon Chambers

Thick GEM (THGEM) fabrication and testing first attempt in India THGEM – a thicker variant of GEMs(>0.4mm) with 0.3 mm holes and annular etching region of 0.1 mm Main advantages: -- Can be made from normal PCB’s using simple mechanical drilling technique. It “can” be damn cheap relative to GEMs ! -- is free from the complex operation of framing and stretching unlike thin GEMs -- easy to handle and hence more robust Constraints: position resolution ~ 500 microns 0.1 mm 0.5 mm 1.2 mm “eccentricity” problems Obstacles: Accuracy in drilling holes and etching of the annular region 10 cm x 10 cm 0.5mm thick double-sided copper clad FR4 material. hole size is 0.3mm and the pitch is 1.2mm made locally. CBM Muon Chambers

MuCh Layout Studies: We have to decide upon : Present constraints : Total number of stations (layers) Total absorber thickness, total no. of absorbers & the absorber material Number of stations (2/3) in between two absorbers Distance between stations & absorber to station distance TOF station? arrangement of readout electronics Present constraints : Absorber material (Fe, Pb, W ) Layer to layer distance >= 10 cm. Layer to absorber distance >= 5cm. CBM Muon Chambers

MuCh Layout Options 2 m CBM Muon Chambers

CBM Muon Chambers

CBM Muon Chambers

Ageing Measurement, High Rate Behaviour Do we need the investigation of GEM ageing? Should be ok for ArCO2 mixture (as shown in many x-ray measurments), but we need to test all construction materials for outgassing.... Moreover, we have in CBM a high rate hadronic environment (also many slow protons), i.e., situation might be different. Do we need to check high rate behavior? GEMs tested to be ok up to 106 Hz/mm2 (factor 10 above CBM), but again: situation behind first absorber might be more challenging (slow fragments)…. At GSI: We are building a FAIR ageing facility to test construction materials used for gas detector in FAIR experiments. Plan to test GEM ageing in hadron beams. CBM Muon Chambers

SUMMARY Double and Triple GEMs have been assembled at VECC. Tests performed with radioactive sources as well with proton beams at GSI. We are also trying to develop THGEM boards locally. Test with proton beams: Double GEM and triple GEMs coupled to the first prototype of n-XYTER readout chip. – preliminary response looked encouraging. -- charged particle detection efficiency needs to be still higher. investigations underway, using tests with cosmic rays. Next test beam: two chambers of 3x3 sq. mm 4x4 sq. mm chamber would require 8 FEBs. May also skip resistor protection Several layout s of the actual design of the Muon Chamber under discussion. Actual size of large GEMs for the final chamber is still under consideration. CBM Muon Chambers