Study On Position Resolution Of Resistive Plate Chamber Based On Cosmic Ray Muon

In order to ensure nuclear non-proliferation, nuclear materials monitoring andtesting technology is becoming more important with the fact of more and moreterrorist actions. Radiography of high z material with muon from cosmic ray is anovel technology for heavy nuclear material detection. Using cosmic ray muon asparticle source and a resistive plate chamber with high position resolution as muontracking detector, a testing system is successfully developed to realize high z materialradiography with cosmic ray. As key part of the detector system, resistive platechamber, a kind of gaseous detector, is need to study and improve position sensitivity.The MRPC, multi-gap resistive plate chamber, has very good efficiency and timeresolution. An experimental result of60ps with over90%efficiency has beenobtained. Recent Study demonstrates that there is high probability of good positionresolution in one dimension or two dimensions for MRPC. The RPC has a goodperformance in time and spatial resolution in one dimension, which has beenconfirmed in many experiments. In spite of some difficulties of theory, successfulexperiment has been carried on in India for RPC used as two-dimension positiondetector.A prototype of MRPC with two-dimension readout has been designed andassembled in our group. Experiments based on muon from cosmic rays have beencarried on, which use PMT signal coincidence system as trigger. The analysis resultof some parameters related to spatial resolution indicates that MRPC can be used astwo-dimension position detector so long as suitable signal ground and readout circuit have been designed to suppress noise and reflection. In some cases, the signaltransmission is more crucial than the signal generation.We also test some MRPC-style and RPC-style one-dimension detectors. We findMRPC has better performance than RPC on one-dimension spatial resolution and thesignal-to-noise ratio is very high. A result of better than100μm spatial resolution hasbeen obtained. And the experiment results clearly show that two-dimension readoutstructure causes serious adverse influence for signal quality and signal-to-noise ratio,becoming the focus of study on position sensitive detector.