Speaker
Saikat Biswas
(GSI - Darmstadt)
Description
All over the world, mainly scintillator-based detectors are being used for PET Imaging. Due to the high cost of the existing systems, extensive R&D is being performed to find an alternative detector. Multi-gap Resistive Plate Chamber (MRPC) with time resolution ~ tens of pico-seconds is considered to be a good alternative. In this work we present the development of Bakelite and glass-based MRPC systems for their applications in PET imaging.
MRPC is a gas filled detector made of highly resistive (bulk resistivity ~ $10^{11}$ - $10^{12}$ Ω cm, e.g. bakelite, glass) electrodes consisting of several small gas gaps (10 to 100 gaps of 0.2 mm to 1 mm width) and operates at atmospheric pressure. Smaller and larger number of gaps improves the time resolution. In MRPC, the total gas volume is divided into a number of small gaps with equal width by inserting intermediate resistive plates with bulk resistivity ~ $10^{11}$ - $10^{12}$ Ω cm between the two outermost resistive plates.
A 20 cm × 20 cm MRPC prototype with four 0.6 mm gap has been fabricated with 1.6 mm thick P-120 grade bakelite sheets and tested in a cosmic ray test bench in the streamer mode with a gas mixture of argon, iso-butane and tetra-fluroethane (R-134a) in 55/7.5/37.5 volume mixing ratio. Silicone coating has been applied over all the inner surfaces to make the surface smooth.
Optional extended abstract
In this study the efficiency, counting rate, leakage current and time resolution of the module have been measured. The efficiency plateau above 95% has been obtained with the time resolution ~ 2 ns.
One glass MRPCs of 20cm x 14cm dimension, having six gaps each of 200 µm width has been fabricated and tested in avalanche mode with a gas mixture of Freon/iso-butane/SF6 in 95/4.5/0.5 mixing ratio. The efficiency of ~ 90% and time resolution ~ 450 ps had been achieved.
Methods of fabrication of all the prototype MRPCs, mode of operation and the test results will be presented.
Primary author
Saikat Biswas
(GSI - Darmstadt)
Co-authors
Mr
Arindam Roy
(VECC)
Mr
Arnab Banerjee
(VECC)
Mr
Ganesh Das
(VECC)
Dr
Sanjoy Pal
(VECC)
Dr
Subhasis Chattopadhyay
(VECC)
