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In the CBM (Compressed Baryonic Matter) experiment constructed at the Facility for Anti-proton and Ion Research (Fair) at GSI, Darmstadt, Germany, MRPC(Multi-gap Resistive Plate Chamber) is adopted to construct the large TOF (Time-of-Flight) system to achieve an unprecedented precision of hadron identification, benefiting from its good time resolution, relatively high efficiency and low building price. According to the particle flux rate distribution, the whole CBM-TOF wall is divided into four rate regions named Region D, C, B and A (from inner to outer). Aiming at the Region C and B where the rate ranges from 3.5 to 8.0 kHz/cm 2 , we've developed a kind of double-ended readout strip MRPC. It uses low resistive glass to keep good performance of time resolution under high-rate condition. The differential double stack structure of 2x4 gas gaps help to reduce the required high voltage to half. There are 24 strips on one counter, and each is 270mm long, 7mm wide and the interval is 3mm. Ground is placed onto the MRPC's electrode and feed through is carefully designed to match the 100Ω impedance of PADI electronics. The prototype of this strip MRPC has been tested with cosmic ray, a 98% efficiency and 60ps time resolution is gotten. In order to further examine the performance of the detector working under higher particle flux rate, the prototype has been tested in the 2014 October GSI beam time and 2015 February CERN beam time. In both beam times a relatively high rate of 1 kHz/cm 2 was obtained. The calibration is done with CBM ROOT. A couple of corrections has been considered in the calibration and analysis process (including time-walk correction, gain correction, strip alignment correction and velocity correction) to access actual counter performances such as efficiency and time resolution. An efficiency of 97% and time resolution of 48ps are obtained. All these results show that the realsize prototype is fully capable of the requirement of the CBM-TOF, and new designs such as self-sealing are modified into the strip counter prototype to obtain even better performance.

In Fourier transform ion cyclotron resonance (ICR) spectrometry until now either positive or negative ions (including electrons) could be trapped, due to the trapping potential applied. In the present article, the theory of simultaneous trapping of positive and negative ions, and the experimental realization are presented. Trajectory calculations for the ions trapped with both charge polarities are described. The new ICR cell employs a new kind of trapping electrodes, constructed with layers of grids. The simultaneous storage is illustrated by experimentals with sulfur hexafluoride.

A: A muon tomography system named Tsinghua University cosmic ray Muon tomography (TUMUTY) facility based on Multi-Gap Resistive Plate Chamber (MRPC) has been built in Tsinghua University in 2012. Our research is focused on developing a muon non destructive testing system that will be used in homeland security operations such as custom inspections, airport security and so on. The gases normally used to operate MRPCs (C 2 F 4 H 2 , SF 6 and i-C 4 H 10 .) have a high global warming potential. Eco-gas is a choice to solve this problem, but it will greatly increase the overall cost of the system. On the other hand, we can also reduce the greenhouse pollution by lowering the airflow to the chamber. In this paper, a sealed MRPC prototype filled only with C 2 F 4 H 2 has been designed and studied. The prototype has a sensitive area of 500 mm • 500 mm, and it can work very well at an extremely low gas flow of 0.5 ml/min. Moreover, we also studied the performance of the detector under a mode without gas exchange. The result shows that the detector can work for more than 60 hours without gas exchange. Under this mode, the average gas flow of the detector reduces to 0.05 ml/min.

A: A high time resolution Multi-gap Resistive Plate Chamber (MRPC) is proposed for the TOF system of SoLID experiment at Jefferson Lab. Efforts have being devoted to the research of a new MRPC structure, aiming at a time resolution of 20 ps. Two 32-gap MRPCs with 104 µm gap thickness have been developed for the initial test. By using the fast amplifier and waveform digitizer system, the performace of these MRPC detectors is studied using the cosmic rays. Time resolution of the order of 20 ps and efficiency around 95% are obtained. Detector simulations are simultaneously carried out for MRPCs with different structures. Meaningful results and future plans are discussed in detail. K: Detector modelling and simulations II (electric fields, charge transport, multiplication and induction, pulse formation, electron emission, etc); Instrumentation and methods for time-offlight (TOF) spectroscopy; Resistive-plate chambers; Timing detectors 1Corresponding author.