1. Cosmic Ray Test of INO RPC Stack M. Bhuyan 1, V.M. Datar 2, S.D. Kalmani 1, S.M. Lahamge 1, N.K. Mondal 1, P. Nagaraj 1, S. Pal 1, L.V. Reddy, A. Redij 1, D. Samuel 1, M.N. Saraf 1, B. Satyanarayana 1, R.R. Shinde 1 and P. Verma 1 India-based Neutrino Observatory (INO) Collaboration 1 Department of High Energy Physics, Tata Institute of Fundamental Research, Mumbai 400005, India 2 Nuclear Physics Division, Bhabha Atomic Research Centre, Mumbai 400085, India

2. Plan of my talk Introduction to INO RPC system. Early results. Construction of 1m X 1m RPCs. Cosmic ray test stand and the DAQ system. RPC performance studies using cosmic muons. Monitoring long term stability of INO RPCs. Future outlook and summary.

3. INO RPC system

4. 4 INO Detector – Channel Count No of modules 3 Module dimension 16 m X 16 m X 12 m Detector dimension 48 m X 16 m X 12 m No of layers 140 Iron plate thickness 6 cm Gap for RPC trays 2.5 cm Magnetic field 1.5 Tesla RPC unit dimension 2 m X 2 m Readout strip width 2 cm No. of RPCs/Road/Layer 8 No. of Roads/Layer/Module 8 No. of RPC units/Layer 192 Total no of RPC units 27000 No of Electronic channels 3.6 X 10 6

5. 5 5 Cosmic Muon Test using small RPCs Stack of 10 RPCs Gas unit Telescope DAQ

6. 6 6 Early results

7. 7 RPC building blocks

8. 8 Fabrication of 1m x 1m RPCs

9. 9 INO 1m X 1m RPC Stack

10. Constructional details of the gas system 10 F ront view Internal view Rear view

11. VME BASED DAQ SETUP X strip data Y strip data Timing info Digital Front End Analog Front End Trigger Module Event Trigger Event/ Monitor Data VME CRATE Scaler TDC Readout Module Linux based DAQ software (C++, Qt, ROOT) Interrupt Based Multi-Threaded Graphical User Interface Online 2D/3D Event Display RPC Strip Monitoring Online Error Reporting RPC Stack Poster by Deepak Samual for more details about INO DAQ

12. 12 Design and implementation of the data acquisition system 200 boards of 13 types Custom designed using FPGA,CPLD,HMC,FIFO,SMD

13. 13 Some interesting cosmic ray tracks

14. Track Reconstruction Zenith Angle distribution of cosmic ray tracks distribution of fitted tracks

15. Study of RPC performance using cosmic rays Strip Multiplicity due to crossing muons Track residue in mm Image of a RPC using muons

16. RPC efficiency

17. RPC timing study Poster by S. Pal for more details on timing studies

18. Particle direction using time information Velocity ( distribution ( linear)Velocity ( ) distribution (log) Average layer-wise time plot for muon tracks in the RPC stack.

19. Long term monitoring of RPC currents

20. Monitoring of strip counting rate

21. Summary We have successfully built and operated Glass RPCS in avalanche mode. A stack of 12 such RPCs being used continuously to monitor their performances using cosmic muons. Currents and noise rates are being monitored over long periods. No degradation after 2.5 years of operation. The setup will be used for further studies and as a test stand to test new frontend electronics & DAQ.