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Status of INO detector R


TIFR, Mumbai. 2. B.Satyanarayana, TIFR, Mumbai INO Collaboration Meeting, University of Delhi, March 9-10 2007 ... BARC, Mumbai. IITB, Mumbai. SINP & VECC, ... – PowerPoint PPT presentation

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Title: Status of INO detector R

Status of INO detector RD
  • B.Satyanarayana
  • TIFR, Mumbai

INO detector RD centres
  • BARC, Mumbai
  • IITB, Mumbai
  • SINP VECC, Kolkata
  • TIFR, Mumbai
  • Summary

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

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

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
  • Superhylam (Coated with white melamine)
  • Grade P-1001 (Coated with natural colour
  • Resistivities of about 1-2?1011 O-cm obtained

A sample of measurements
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

Long term efficiency monitoring
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

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
  • Some commercial fast chips are also being tried

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

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

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

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

Development of pickup panels
  • Using till now, pickup panels barrowed from
  • 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

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

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

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),

Software tools and utilities
  • On-line web portal for monitoring chambers under
    test as well as ambient conditions of the
  • 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

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