7 Apr 2010Paul Dauncey1 Tech Board: DECAL beam test at DESY, March 2010 Paul Dauncey

7 Apr 2010Paul Dauncey 2 Main aims (Tech Board 3 Feb) SPiDeR had to be more generic than just ILC Certainly more than just ILC DECAL DECAL sensor (TPAC) not the only sensor being tested Fortis and Cherwell sensors for studying tracking applications Two main strands DECAL performance General performance of CMOS MAPS For DECAL Realistic resolution depends on charged particle density in EM shower core Predicted by simulation to be O(100/mm 2 ) but not verified at 50  m granularity Main aim this year is to measure real shower density with electrons

7 Apr 2010Paul Dauncey 3 MAPS variants (Tech Board 3 Feb) Deep P-well vs non-deep P-well Expect deep P-well to have higher collection efficiency High-resistivity vs standard silicon Collection by diffusion, so slow; O(100ns) With high-resistivity, can have electric field to suck out charge; faster, more efficient and probably more radiation hard Epitaxial layer depth; 5 vs 12 vs 18  m Changes amount of signal charge generated

7 Apr 2010Paul Dauncey 4 DESY beam test (Tech Board 3 Feb) Three weeks as main user, limited to 1-6GeV electrons Most of March; overlaps UTA collaboration meeting and LCWS10 Technically, close to a repeat of CERN beam test so “straightforward” Use EUDET telescope; DAQ integration ongoing Measure efficiency of all sensors variants available for “MIPs” Compare with CERN results with pions to check for non-MIP effects Measure shower core densities in EM showers As a function of energy and of tungsten converter depth Need accurate tracking to locate shower centre

7 Apr 2010Paul Dauncey 5 SPiDeR shifters University of Birmingham H. Bansil, T. McLaughlan, T. Price, N.Watson University of Bristol D. Cussans, J. Goldstein, R. Page, J. Velthuis University of Edinburgh H. Tabassam Imperial College London P. Dauncey University of Oxford R. Gao Rutherford Laboratory M. Stanitzki, J. Strube, G. Zhang Total: 14 people for three weeks = 54 shifts (72 person-shifts)

7 Apr 2010Paul Dauncey 6 Complete TPAC system DAQ PC USB_DAQ master Sensor mechanical support CAEN power supply USB_DAQ readout

7 Apr 2010Paul Dauncey 7 Data-taking overview 47M bunch trains × 3.2ms/bunch train = 150k sec live time = 42 hours Corresponds to 8% duty cycle overall Mainly due to DAQ rate; 40Hz bunch train rate gives 13% duty cycle Roughly 65% running, averaged over whole three weeks Accelerator maintenance period

7 Apr 2010Paul Dauncey 8 Temperature Temperature was significant issue at CERN last summer High temperatures ~40C meant sensors could lose their configuration Always below 30C at DESY Much more stable operation Jumps due to changes of mode of operation, i.e. layout of sensors in stack Hi-tech ( ) air blower

7 Apr 2010Paul Dauncey 9 EUDET telescope Not as useful as we had hoped for DECAL work Had not been run continuously since being installed at DESY Operation was rather variable for the first two weeks Heroic efforts from Ingrid and (particularly) Igor Rubinsky helped to fix it DECAL stack could not get closer than ~1m from the last telescope plane Low momentum beam so completely multiple scattering limited Resolution at DECAL sensors ~  m » sensor pixel size

7 Apr 2010Paul Dauncey 10 Tracking mode Four standard sensors in outer layers Construct tracks using these only; no need for EUDET telescope Two sensors-under-test in the inner two layers Project track to these to measure efficiency Identical method (and analysis) to CERN

7 Apr 2010Paul Dauncey 11 Tracking mode II Used adapted version of George’s semi-online monitoring E.g. number of sensor pixels firing vs pixel time difference from PMT hits All standard sensors One non-deep p-well sensor

7 Apr 2010Paul Dauncey 12 Tracking mode III Hi-res Standard CERN TypeNumber tested Standard4 Non-deep p-well2 12  m hi-res 3 18  m hi-res 2 Only fully tested two of the four variants at CERN Did all four with at least two sensors each at DESY Threshold scan for all cases

7 Apr 2010Paul Dauncey 13 Shower mode Inserted differing numbers of tungsten sheets between sensors Each sheet was 3mm, corresponding to 3/3.5mm = 0.86X 0 Fallback due to uncertainty of EUDET telescope operation Use four TPAC sensors for pre-tungsten tracking

7 Apr 2010Paul Dauncey 14 Shower mode II Sensor hit correlations for layer 3 (before tungsten) and layer 4 (after tungsten) Both vs hits in layer 0

7 Apr 2010Paul Dauncey 15 Shower mode III Also did copper (and a very small amount of iron and lead) Radiation length of copper =14.3mm (c.f. tungsten = 3.5mm) Limited for copper in number of X 0 which would fit into stack MaterialTungstenCopper 0.44X 0 0.9X 0 1.7X 0 3.4X 0 5.1X 0 6.9X 0 8.6X X 0 All done at 1, 2, 3, 4 and 5 GeV No 6 GeV beam as DESY2 only running at 6.3GeV

7 Apr 2010Paul Dauncey 16 CERN beam test, May/Sep 2010 Requested two weeks as main user, GeV electrons, 120GeV pions Also requested EUDET telescope so identical DAQ to DESY Now know it is not essential for TPAC (but is for other SPiDeR tests) Extend shower density measurements up to 100GeV Much bigger level arm; 1-100GeV rather than 1-5GeV Better check of simulation New idea: if EUDET telescope performing well Cross-check density measurements using telescope stand-alone Place tungsten between the two arms and measure hits in downstream arm Cross-check any MIP efficiencies if any variants look odd Using pions (in parallel with other SPiDeR tests) But still very limited effort available Probably can just about cover shifts Main problem would be analysis, particularly towards the end of 2010 Have a meeting in two weeks to decide if we will go ahead with beam runs