RECENT PROGRESS IN LOW-TEMPERATURE SILICON DETECTORS

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RECENT PROGRESS IN LOW-TEMPERATURE SILICON
DETECTORS
Univ. Catholique de Louvain, Belgium Helsinki
Institute of Physics, Finland Helsinki Univ. of
Technology, Finland Univ. of Turku, Finland ILK
Dresden, Germany IEKP, Univ. of Karlsruhe,
Germany Univ. of Munich, Germany INFN and Univ.
of Naples, Italy INFN and Univ. of Florence,
Italy LIP Lisbon, Portugal Ioffe PTI, Russia JSI
Ljublijana, Slovenia Univ. of Geneva,
Switzerland CERN, Switzerland LHEP, Univ. of
Bern, Switzerland Univ. of Brunel, UK Univ. of
Glasgow, UK BNL, USA (Totally 50 scientist)
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OUTLINE

• Why cold temperature
• Activities and projects
• Recent progress
• Summary

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WHY COLD TEMPERATURE SILICON DETECTORS?(130 K)

• Radiation hardness
• ... improves by factor of 10, due to Lazarus
  effect
• -gt tolerance to very high luminosities (e.g.
  Super-LHC 1035 cm-2s-1)
• Charge carrier mobility (electrons and holes)
• ... improves by factor of 5
• -gt very fast sensors
• Thermal conductivity
• ... improves by factor of 3, from 300 K to 130 K
• -gt evacuation of heat from Si modules -gt
  facilitation of engineering design
• Leakage current (bulk surface)
• ... becomes negligible even for heavily
  irradiated silicon

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ACTIVITIES AND PROJECTS

• 1. Basic Research
• Defects in bulk Silicon
• 2. Device Physics
• Cryogenic detectors
• Edgeless detectors
• Cryogenic modules
• Pixel detectors
• Microstrip detectors
• 4. Common projects
• RD39/TOTEM (Total Cross Section, Elastic
  Scattering and Diffraction Dissociation at the
  LHC )
• RD39/COMPASS (COmmon Muon Proton Apparatus for
  Structure and Spectroscopy)
• RD39/RD60 (Study of Prompt Dimuon and Charm
  Production with Proton and Heavy Ion Beams at SPS)

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RECENT PROGRESS

• Edgeless detectors for CERN/TOTEM
• 2. Thermomechanical tests on Silicon module
  structures for CERN/TOTEM
• 3. Cold Deep SubMicron readout circuits (APV25)
  for cryogenic microstrip tracker modules for
  CERN/COMPASS
• 4. Beam telescopes for protons and lead ions for
  CERN/NA60
• 5. Processing and testing Magnetic Czochralski
  Silicon detectors

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1. EDGELESS SILICON STRIP DETECTORS (TOTEM)

• TOTEM detectors are very close to beam line (
  1 mm) to measure elastic scattering
• detectors must be active down to the edges with
  no dead areas
• Dicing by laser cutting or by scribing /
  Cutting from back n or from front p surface
• Immediately after dicing
• IL(VFD85V) ? 1 mA Vbreak ? 80-100 V
• After 12h _at_ RT and diced from the non-sensitive
  back surface
• IL (VFD85V) ? 1 uA IL (400V) ? 40 uA
• After further edge etching treatment
• IL (VFD85V) ? 0.15 uA IL (400V) ? 0.5 uA
• Laser cutting more controllable
• Good detector performance (IV, CV, CCE)

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2. THERMOMECHANICAL TESTS FOR GLUED MODULES
(TOTEM) THERMAL SIMULATIONS with ANSYS
Materials used in the simulation Strip Detector
(30x30) ? Silicon Support (47x63) ?
Silicon Hybrid (47x28) ? Al2O3 Pitch-adapter
(47x9) ? Silicon Cooling pipe (0.5 ID) ?
CuNi Spacer (47x9) ? Silicon Components are
glued together with radiation resistant cryogenic
epoxy
Thermal boundary conditions APV25 (2.31
mW/channel) ? 1.2 W Thermal radiation ? 235
mW Argon Bulk Temperature ? 120 K Heat Transfer
Coefficient ? 104 W/m2K
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2b. CLOSED CYCLE COOLING SYSTEM (TOTEM)
TOTEM detectors must be radiation hard ?
detector modules need efficient cryogenics
cooling is with cryogenic fluid pumped
through a microtube circuit (? 0.3 mm) by a
cryogenic micropump - cryogenic fluid two-phase
Argon - cooling power 10-100 W - Pump speed
0-6000 rpm - flow rate 100 mg/s 5.2 ml/min
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3. COLD APV25 DSM READOUT CIRCUITS (COMPASS)
COMPASS Tracker operates cryogenic silicon
microstrip detector modules at high
intensities DSM (Deep SubMicron) front-end
readout chip APV25 was measured at RT and at
130K APV25s signals are faster and higher at
130 K cryoacceleration Optimum at 110 K
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4. BEAM TELESCOPES FOR PROTONS AND LEAD IONS
(NA60)
Both telescopes have four planes of
single-sided silicon microstrip detectors In
the Proton telescope, fast cold CMOS Deep
SubMicron (DSM) preamplifiers demonstrated
cryogenic acceleration and lowered noise at the
operating temperature of 130 K (Fig.1) Lead Ion
telescope was successfully operated up to the
dose of 0.9 GGy in the center of the beam spot
(Fig.2)
Fig.1
Fig.2
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5. MAGNETIC CZOCHRALSKI SILICON DETECTORS
ELECTRICAL PERFORMANCE IL(900 V) 3 uA (A32.5
cm2) Vfd 420 V (380 um)
DETECTOR PROCESSING Simple four mask level
process
RADIATION TOLERANCE Being tested gamma,
neutron, proton irradiations
DETECTION PERFORMANCE Resolution ? 10
um Efficiency ? 95 Signal/Noise ? 10
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SUMMARY

• 1. Edgeless detectors diced from the
  non-sensitive back surface and aged one day in
  air performed well as detectors. Edge etching
  treatment further improved the detector
  characteristics.
• 2. Cryogenic micropump was succesfully developed
  for the cooling system of Silicon microstrip
  detector modules operating at cryogenic
  temperatures.
• Good operation of APV25 chip was demonstrated at
  cryogenic temperatures.
• Beam telescopes for protons and lead ions were
  succesfully operated at cryogenic temperatures.
• Silicon detectors made on Magnetic Czochralski
  Silicon were processed, tested electrically,
  tested in muon beam, and irradiated.

It is possible to design and operate radiation
hard tracking detectors at cryogenic temperatures