Status of INO detector R

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Status of INO detector RD

• B.Satyanarayana
• TIFR, Mumbai

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INO detector RD centres

• BARC, Mumbai
• IITB, Mumbai
• SINP VECC, Kolkata
• TIFR, Mumbai
• Summary

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Gas mixing system
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Setting up of a muon telescope
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Spacers, nozzles and buttons
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Bakelite RPC fabrication
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Glass characterisation studies
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Current status and future plan

• Problem of high dark currents with glass RPC
• Trying to make RPCs with bakelite sheets with and
  without linseed oil
• Will build glass RPCs also in parallel
• Assembling strip sized scintillator paddles for
  setting up telescope and to record efficiencies
  from single RPC strips

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Status of RPC Lab at IITB

• Lab space obtained and setup
• Gas system will arrive early next week
• Electronic modules, power supplies, materials
  being procured
• Basic cosmic ray test setup exists
• A multi-gap RPC built
• 4 gaps with 375µm spacing
• 2mm float glass used
• Outer most surfaces coated with graphite

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Work on bakelite chambers

• One Chinese chamber of a ft2 in area, made using
  oil-less bakelite sheets, was studied
• Efficiency plateau of over 90 recorded, starting
  at high voltage of about 8KV, in streamer mode
• One chamber of a ft2 in area, was built using
  Chinese bakelite sheets
• Efficiency plateau of over 92 recorded, starting
  at high voltage of about 9.2KV, in streamer mode
• One chamber of a ft2 in area, was built using
  local bakelite sheets
• Chamber draws very high dark current
• Bulk resistivities of local bakelite varieties
  measured
• Superhylam (Coated with white melamine)
• Grade P-1001 (Coated with natural colour
  melamine).
• Resistivities of about 1-2?1011 O-cm obtained

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A sample of measurements
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Long-term study of small chambers

• 2mm float glass from Japan
• Two chambers of one ft2 in area
• Operated in avalanche mode
• R134a (C2F4H2)Iso-butane95.54.5 by volume
• Readout by a G-10 based pickup plate
• Preamp gain of 10?2
• Combined efficiency over 93
• In system for about 18 months
• Reasonably stable behaviour

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Long term efficiency monitoring
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Import of float glass sheets

• 100 sheets from Japan
• 1 m2 in area
• 2mm thick
• 200 sheets through Opera group, Italy
• 1 m2 in area
• 3mm thick
• Chamfered at the corners
• Coated with resistive paint

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Current RPC development work

• Several small sized chambers built using the
  Japanese glass and are being tested they seem to
  be doing well till now
• A couple of 1 m2 chambers were also made and are
  under tests
• Multiple channel, low noise, high gain, high
  bandwidth amplification is a bottle neck
• Solutions using BARC discrete version boards,
  cascades, NIM packaged preamplifier dont seem to
  work well
• Circuit board for cascaded HMC chips is being
  designed will be used in prototype detector as
  well
• Some commercial fast chips are also being tried
  out

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New RPC fabrication jig

• Need for uniform pressure on the glass sheets
  while being glued to the button spacers
• Till now using dead loads distributed through
  metal sheets or wooden boards
• Works fine for small chambers but unsuitable for
  large area chambers
• A pneumatic jig developed to solve this problem
• Cover the RPC assembly with a polythene sheet to
  make a closed volume
• Evacuate the volume using a vacuum pump in a
  closed loop till the epoxy sets in
• Fabricated a few 1 m2 chambers successfully

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RPC mechanics

• Serves many purposes
• Good grounding, RF/EMI shielding
• Uniform pressure for the entire RPC area
• Facilitates uniform gas flow
• Mechanical rigidity and ease of handling
• Provides elegant method to terminate HV, gas, low
  voltage power supplies and signals
• First prototype, housing discrete preamps inside
  was fabricated and being tested
• Improved version will be used for prototype
  chamber

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Studies on resistive coating

• Consultancy by UDCT, Mumbai
• Preparation of paints by Nerolac, Mumbai
• Coating by Unicoats, Mumbai
• Optimisation studies, both in terms of the paint,
  as well as the application are in progress
• Application is still a manual process now
• Long term monitoring of surface resistivity as
  well as coat quality to be studied

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Spacers, nozzles and buttons

• Material Polycarbonate
• Fabricator Ashwin Plastics, Mumbai
• Third and final iteration in progress

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Development of pickup panels

• Using till now, pickup panels barrowed from
  Fermilab
• Foam sandwiched between two aluminum foils using
  heat lamination
• One foil segmented to form pickup strips
• An Indian company (Multivac) was identified to
  produce these panels locally
• Many samples of different materials and geometry
  fabricated and tested for characteristic
  impedance of the strips, dielectric constant of
  the foam, attenuation of the signal through the
  strips etc.
• Specifications of the prototype detector panels
• Foam thickness 5 mm
• Foam density 43 kg/m3           
• Aluminum foil thickness 0.2 mm
• 50 panels are in production

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Mylar sheets

• Used for glass electrode and pickup panel
  isolation
• Using till now, mylar sheets barrowed from
  Fermilab
• Found out that Garfilm EMCL produced by M/s
  Garware Polyester Ltd suits our requirement well
• Thickness 100µm
• Breakdown voltage 13.5KV

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Issues on fast preamplifiers

• Avalanche charges are a factor of 100 smaller
  compared to streamers
• Typical charges 1pC (1mV across 50O load)
• Hence the need for external amplification
  typically 50-100
• BARC, ED designed
• HMC packages are being fabricated at BEL

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Electronics and DAQ for prototype

• Design of all components of the data acquisition
  system was completed
• Production and assembly of nearly all the circuit
  boards and modules is completed
• Major sub-systems were integrated along with the
  on-line data acquisition software successfully
• Hybrid version of the preamplifiers being
  fabricated by Bharat Electronics Limited (BEL),
  Bengalooru

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Software tools and utilities

• On-line web portal for monitoring chambers under
  test as well as ambient conditions of the
  laboratories
• Web based electronic log book
• Web based electronic inventory utility
• Agenda server
• All these tools can be scaled up and deployed for
  prototype detector and even for ICAL

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Summary and plans

• Production of 1 m2 chambers using Italian glass
• Production of 1 m2 chambers using Japanese glass
  for prototype detector
• Work on bakelite versions to continue (at SINP,
  VECC, BARC etc)
• Long term tests and characterisation of large
  area chambers to continue
• Finalisation of various materials, processes and
  vendors, RPC mechanics etc
• Final integration of electronics and DAQ for
  prototype detector
• New labs getting equipped can take up dedicated
  and detailed studies