# Multigap Resistive Plate Chambers for Time of Flight Applications
## 3 Applications in Large Experiments
### Developments for Future ToF Systems  
#### 3.3.1 High Rate and Ultrahigh Time Resolution MRPC  
Although the science of the electromagnetic force between the atomic nucleus and the electrons is well understood, we still know little about the nucleon's structure and the quarks and gluons that compose the nuclei. The future experiments with higher luminosity and beam energy, such as the 12 GeV program of JLab [76,77] and the electron-ion collider (EIC) [78] at Brookhaven Lab, will provide a powerful tool and simultaneously impose strict requirements on the detector devices. Figure 8: Efficiency, cluster size, noise (**a**) and time resolution (**b**) with irradiation time. In (**b**) the time resolution is analyzed by two methods: label (**A**) is the results for every 5 days and label (**B**) is the results with time. Reproduced with permission from [PERSON] et al., Chinese Physics C; published by Chinese Physical Society and the Institute of High Energy Physics of the Chinese Academy of Sciences and the Institute of Modern Physics of the Chinese Academy of Sciences and IOP Publishing Ltd, 2016 [72]. Figure 9: (**a**) System time resolution obtained with relativistic pions. The distribution is fitted by a gaussian function, as shown in the black line. (**b**) \(1/\beta\) versus particle momentum. For the SoLID experiment [79; 80] at JLab, the particle separation for different ToF time resolutions and for the 8 m flight distance can be calculated according to Equation (4), as shown in Figure 10. A ToF with a time resolution of 20 ps and a rate capability of 10 kHz/cm\({}^{2}\) is required to achieve K/\(\pi\) separation at the momentum range of 1-7 GeV/c. For hadron identification in the future EIC detector, the Cherenkov detector is thought to be the only possibility of covering the high momentum range (5-50 GeV/c, depending on the polar angle), while ToF or \(dE/dx\) (like a TPC) system is needed to cover the low momentum range (up to a few GeV/c) [81]. At the typical distance of 4 m available on the hadron-going side, a 10 ps ToF would provide \(\pi\)/K separation up to 7 GeV/c. Several R&D projects currently have been putting effort into investigating high-performance detectors. [PERSON]. [PERSON] et al. [82] from the LHC-ALICE group developed a 24 gap MRPC with a gap width of 160 \(\upmu\)m. It was arranged into 4 stacks, each with 6 gaps. The 400 \(\upmu\)m thick float glass plates were employed as the resistive plates. Using the NINO electronics and the oscilloscope-based system, a time resolution of 27 ps for cosmic ray test and 21 ps for beam test has been obtained. [PERSON] et al. [83; 84] has built and carefully studied three kinds of 20-gap MRPCs with very thin (0.28 mm) float glass plates and different gap sizes of 160 \(\upmu\)m, 140 \(\upmu\)m and 120 \(\upmu\)m. They are able to reach an efficiency of 90% at a flux rate of around 20 kHz/cm\({}^{2}\), while the 140 \(\upmu\)m-MRPC gives the best time resolution of 25 ps. In order to further improve the rate capability, they built a 10-gap MRPC [85] with the low-resistivity glass from Picotech SAS. During the beam test at ELBE, this MRPC always keeps the efficiency above 95%. The time resolutions of 36 ps and 50 ps are obtained at the rate of 2 kHz/cm\({}^{2}\) and 100 kHz/cm\({}^{2}\), respectively. Tsinghua University and USTC [79] have been putting much effort into carrying out R&D of the required detector for SoLID-ToF. Just like the CBM-ToF, the low resistive silicate glass is employed as the resistive plate to achieve a high rate capability. To better understand the detector's working principles and improve the performance, a standalone simulation framework of the MRPC detector has been built and carried out [86; 87]. The energy deposition produced by the passing particles is simulated based on the PAI model [88], which is proved to be effective for very thin absorbers.