Status of INO detector R&D

1. Status of INO detector R&D B.Satyanarayana TIFR, Mumbai

2. INO detector R&D centres • BARC, Mumbai • IITB, Mumbai • SINP & VECC, Kolkata • TIFR, Mumbai • Summary B.Satyanarayana, TIFR, Mumbai INO Collaboration Meeting, University of Delhi, March 9-10 2007

3. Gas mixing system B.Satyanarayana, TIFR, Mumbai INO Collaboration Meeting, University of Delhi, March 9-10 2007

4. Setting up of a muon telescope B.Satyanarayana, TIFR, Mumbai INO Collaboration Meeting, University of Delhi, March 9-10 2007

5. Spacers, nozzles and buttons B.Satyanarayana, TIFR, Mumbai INO Collaboration Meeting, University of Delhi, March 9-10 2007

6. Bakelite RPC fabrication B.Satyanarayana, TIFR, Mumbai INO Collaboration Meeting, University of Delhi, March 9-10 2007

7. Glass characterisation studies B.Satyanarayana, TIFR, Mumbai INO Collaboration Meeting, University of Delhi, March 9-10 2007

8. 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 B.Satyanarayana, TIFR, Mumbai INO Collaboration Meeting, University of Delhi, March 9-10 2007

9. 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 B.Satyanarayana, TIFR, Mumbai INO Collaboration Meeting, University of Delhi, March 9-10 2007

10. 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1011Ω-cm obtained B.Satyanarayana, TIFR, Mumbai INO Collaboration Meeting, University of Delhi, March 9-10 2007

11. A sample of measurements B.Satyanarayana, TIFR, Mumbai INO Collaboration Meeting, University of Delhi, March 9-10 2007

12. 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-butane::95.5%:4.5 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 B.Satyanarayana, TIFR, Mumbai INO Collaboration Meeting, University of Delhi, March 9-10 2007

13. Long term efficiency monitoring B.Satyanarayana, TIFR, Mumbai INO Collaboration Meeting, University of Delhi, March 9-10 2007

14. 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 B.Satyanarayana, TIFR, Mumbai INO Collaboration Meeting, University of Delhi, March 9-10 2007

15. 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 don’t 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 B.Satyanarayana, TIFR, Mumbai INO Collaboration Meeting, University of Delhi, March 9-10 2007

16. 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 B.Satyanarayana, TIFR, Mumbai INO Collaboration Meeting, University of Delhi, March 9-10 2007

17. 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 B.Satyanarayana, TIFR, Mumbai INO Collaboration Meeting, University of Delhi, March 9-10 2007

18. 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 B.Satyanarayana, TIFR, Mumbai INO Collaboration Meeting, University of Delhi, March 9-10 2007

19. Spacers, nozzles and buttons • Material: Polycarbonate • Fabricator: Ashwin Plastics, Mumbai • Third and final iteration in progress B.Satyanarayana, TIFR, Mumbai INO Collaboration Meeting, University of Delhi, March 9-10 2007

20. 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 B.Satyanarayana, TIFR, Mumbai INO Collaboration Meeting, University of Delhi, March 9-10 2007

21. 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 B.Satyanarayana, TIFR, Mumbai INO Collaboration Meeting, University of Delhi, March 9-10 2007

22. Issues on fast preamplifiers • Avalanche charges are a factor of 100 smaller compared to streamers • Typical charges 1pC; (~1mV across 50Ω load) • Hence the need for external amplification; typically 50-100 • BARC, ED designed • HMC packages are being fabricated at BEL B.Satyanarayana, TIFR, Mumbai INO Collaboration Meeting, University of Delhi, March 9-10 2007

23. 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 B.Satyanarayana, TIFR, Mumbai INO Collaboration Meeting, University of Delhi, March 9-10 2007

24. 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 B.Satyanarayana, TIFR, Mumbai INO Collaboration Meeting, University of Delhi, March 9-10 2007

25. 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 B.Satyanarayana, TIFR, Mumbai INO Collaboration Meeting, University of Delhi, March 9-10 2007