Xingming Fan

Design and construction of muon tomography facility based on MRPC detector for high-Z materials detection

Muon tomography with cosmic ray muons is a novel technology for high-Z material detection. The tomographic imaging is based on multiple coulomb scattering of cosmic ray muons in matter, which requires large-scale, high-efficiency, high spatial resolution detectors for tracking of incoming and outgoing muons. From previous studies, the multi-gap resistive plate chamber (MRPC) would be an excellent and inexpensive choice for this application, which also offers the possibility of introducing energy information of muons by TOF measurement for image reconstruction of muon tomography. A prototype of muon tomography facility with 6 layers large-scale MRPC detectors has been designed and is under construction, the preliminary results of muon tomography and design details of the MRPC detectors and electronics were presented.

Conceptual design of the CBM-TOF wall with real-size high-rate MRPC modules based on the newly developed chinese doped glass

The Compressed Baryonic Matter experiment at the future Facility for Antiproton and Ion Research will use a time-of-flight (TOF) wall for hadron identification, based on the MRPC technology. The wall will be placed at 10m distance from the target covering an area on the order of 150m 2 . We propose here a realistic design for building the TOF wall by resorting to a single technology based on low-resistivity doped glass and relying on small structural modifications of the modules developed and tested during the last two years. The performance of real-size modules is also summarized. XI workshop on Resistive Plate Chambers and Related Detectors (RPC2012) INFN-Laboratori Nazionali di Frascati, Italy February 5-10, 2012

Aging test of high rate MRPC

A new kind of low resistivity glass has been developed. Its volume resistivity is on the order of 10 10 Ωcm and MRPCs assembled with it show a very promising rate capability (>25 kHz/cm 2 ). This new detector has a very important range of application in high energy physics experiments such as FAIR-CBM, LHC-ATLAS or Jlab-SOLID, to mention some. In this paper we report new results related to its long-term behavior (ageing). The module has been irradiated by X-rays at a mips-equivalent flux of 15kHz/cm 2 , for 300 hours and for a released charge totaling 0.22C. No noticeable degradation could be observed. Compared to common glass MRPCs, the newly developed high rate counter responds faster to sudden irradiation.

High position resolution MRPC developed for muon tomography

In order to achieve sub-millimeter position resolution for tracking cosmic ray muon for building muon tomography system, a prototype of MRPC with narrow strips readout is designed and assembled. The width of readout pitch of the module is 2.54mm. Experiments by cosmic rays and X-rays have been carried out. After the calibration for each channel, the position is reconstructed by charge distribution across strips using central gravity. The results shows that the time resolution is about 50ps and the spatial resolution can reach 0.36mm. By this detector, we can not only get the muon track, but also get the muon momentum, which will provide more information for image reconstruction.

Preliminary research on performance evaluation and TUCCI model for muon tomography

Muon tomography with cosmic ray muon is a novel technology for high-Z material detection. Preliminary research on performance evaluation method and models for muon tomography is introduced. Cube model and TUCCI model are introduced to evaluate the material discrimination capability and detection capability of high-Z material hidden in cargo container, line-pair model and hole model are introduced to evaluate the spatial resolution of muon tomography. The relationship between image quality and exposure time is also discussed.

Aging test of a real-size high rate MRPC for CBM-TOF wall

A new kind of low-resistivity glass has been developed. Its volume resistivity is on the order of 1010 Ω cm and multi-gap resistive plate chambers (MRPCs), once assembled with it, can be operated at a charged particle flux in excess of 25 kHz/cm2, with very small charge build-up at the plates. This new technology has a wide range of application in high energy physics experiments such as FAIR-CBM, LHC-ATLAS or Jlab-SOLID, to mention some. In this paper we report on results related to its long-term behavior (aging). A 6 × 2-pad CBM module has been irradiated by X-rays at a mips-equivalent flux of 15 kHz/cm2, for 300 hours and for a released charge totaling 0.22 C (50 mC/cm2). Tested in an electron beam before and after exposure, no degradation of the detector performances could be appreciated. As expected, compared to common glass MRPCs, the newly developed high rate counter also responds faster to sudden irradiation.

Production of long-strip multi-gap resistive plate chamber module for the STAR-MTD system

A new Long-strip Multi-gap Resistive Plate Chamber (LMRPC) prototype with 5 gas gaps has been developed for the Muon Telescope Detector (MTD) of the STAR experiment at RHIC in order to reduce the working High Voltage (HV) of previous design. Technical specifications related to the final infrastructure present in the experiment have motivated this effort. Its performance has been measured with cosmic rays. The efficiency of this prototype can reach 98% and the time resolution is around 95 ps. It shows a good uniformity among strips. The noise level is less than 0.2 Hz/cm2. The signal transmission and crosstalk of the modules was measured with a vector network analyzer, showing a good match with simulations within the amplifier bandwidth. A new cosmic-ray test system with long scintillators has been developed to accelerate the Quality Control (QC) process during the mass production of STAR-MTD. A selection of perpendicular cosmic-ray events for more accurate evaluation of the time resolution is achieved. The time resolution with this method is better, albeit with larger error, than the result obtained without any selection. A new spacer is used, resulting in a much reduced streamer ratio at comparable fields. Thirty-two modules have been built with the new spacer by the middle of April of 2012. They have been tested and they all have passed the QC.

A MRPC prototype for SOLID-TOF in JLab

A prototype of Multi-gap Resistive Plate Chamber (MRPC) for the future SoLID time of flight system at JLab has been developed. The counter, trapezoidal in shape, is assembled with the newly developed low-resistive Chinese glass. It has 10 × 0.25 mm gas gaps and 11 readout strips of different lengths. The strip width is 2.5 cm with a strip-to-strip interval of 3 mm. Preliminary tests performed with cosmic-rays showed an efficiency higher than 95% and a time resolution around 50 ps. Results under diffuse/uniform irradiation performed at JLab with scattered high energy electrons showed a time resolution of 70–80 ps and over-95% efficiency up to an incoming flux of 15 kHz/cm2. These performances meet the requirements of the new time of flight system SoLID-TOF.

A realistic design of the CBM-TOF wall based on modules commissioned in-beam

The Compressed Baryonic Matter experiment at the future Facility for Antiproton and Ion Research will use a time-of-flight (TOF) wall for hadron identification, which is at the moment planned to be based on the Multi-gap Resistive Plate Chamber (MRPC) technology. The wall will be placed at 10m distance from the target, covering an area of the order of 150 m2. Over such an area, it will provide a time-of-flight resolution of 80 ps, by resorting to ca. 50000 RPC cells (in multi-strip or multi-pad configuration). Fluxes of quasi-minimum ionizing particles (γβ≥3) as high as 20 kHz/cm2 can be reached in the central region, corresponding to the low polar angle/high rapidity section. We propose here a realistic design for building the TOF wall by resorting to a single technology based on low-resistivity doped glass and relying on small structural modifications of the modules developed and tested during the last two years. Latest results from the modules are summarized. A comprehensive analytic discussion on the counter performance under non-uniform beams, when neglecting non-local effects, is also presented.

Preliminary research on application of muon energy measurement based on TOF for muon tomography

Cosmic-ray muon tomography based on multiple coulomb scattering is typically applied in detecting high-Z materials. The energy of muon also plays an important role in the distribution of the scattering angles, and the information of muon energy would be useful for the image reconstruction. In this paper, a simulation experiment has been conducted to check the feasibility of TOF method applied in measuring muon energy for muon tomography system. The simulation results have been discussed and some preliminary conclusions have also been drawn.