7 Apr 2010 Paul Dauncey 1

Tech Board: DECAL beam test at DESY, March 2010

Paul Dauncey

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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/mm2) but not verified at 50m granularity

• Main aim this year is to measure real shower density with electrons

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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 18m

• Changes amount of signal charge generated

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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

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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)

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Complete TPAC system

DAQ PC

USB_DAQ master Sensor mechanical support

CAEN power supply USB_DAQ readout

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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

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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

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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 ~200-500m » sensor pixel size

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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

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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

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Tracking mode III

Hi-res

Standard

CERN

Type Number tested

Standard 4

Non-deep p-well 2

12m hi-res 3

18m 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

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Shower mode

• Inserted differing numbers of tungsten sheets between sensors

• Each sheet was 3mm, corresponding to 3/3.5mm = 0.86X0

• Fallback due to uncertainty of EUDET telescope operation

• Use four TPAC sensors for pre-tungsten tracking

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Shower mode II

• Sensor hit correlations for layer 3 (before tungsten) and layer 4 (after tungsten)

• Both vs hits in layer 0

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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 X0 which would fit into stack

Material Tungsten Copper

0.44X0

0.9X0

1.7X0

3.4X0

5.1X0

6.9X0

8.6X0

10.3X0 • All done at 1, 2, 3, 4 and 5 GeV

• No 6 GeV beam as DESY2 only running at 6.3GeV

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CERN beam test, May/Sep 2010• Requested two weeks as main user, 10-100GeV 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