Speaker
Mr
Zheng Liang
(University of Science and Technology of China)
Description
Incident cosmic ray particles can interact with atmosphere molecule, which can produce plenty of muons. Due to high penetration ability, muons can be substituted to detect materials that traditional methods, like X-rays, cannot detect. Detectors that measure deviation angle of in-coming and out-coming tracks can give a 3-D density distribution amid in detectors.
We’ve built a muon imaging system prototype based on scintillator position detectors with SiPM readout. The detector is composed of plastic scintillators with wavelength shift (WLS) fibers inside and SiPM readout modules. When cosmic ray muon penetrates through, scintillator will produce photon. Yielded photons can be collected by WLS fibers and then transmitted to SiPM. Charge of SiPM signal will be recorded by the readout electronics and can be used to infer deposit energy in scintillator.
A test system and a GEANT4 simulation program has been set to estimate position resolution of 3 kinds of scintillator structure. The first one is square cross section strip plastic scintillator, coated with reflective paint so as to reflect photons. It’s the most popular structure, and its resolution should be 2.9mm if side length of square is 10mm. The second one is triangle cross section strip scintillator, which is also coated with reflective paint. Position resolution should be better, due to measurement of deposit energy in different strips. Simulation result shows 50% better than square situation. The last one is a whole plate without any cutting and coating. This is the simplest and most economic structure. But shows the worst position resolution and detect efficiency. Experimental data from the test system is close to GEANT4 simulation.
After measurement of detector’s position resolution, we build a muon imaging system. Point of Closest Approach (PoCA) algorithm is used to calculate density distribution.
Summary
We've built a muon imaging system prototype based on scintillator position detectors with SiPM readout. Four layers of position detectors can give deviation angle information. Position resolution of these detectors are different due to different structures, and will be shown in the report. Meanwhile preliminary imaging result using PoCA algorithm will be shown.
Primary author
Mr
Zheng Liang
(University of Science and Technology of China)
