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Development of the Four-gap Resistive Plate Chambers for High-rate Particle Triggers in CMS

초록/요약

In this thesis, we report of a R&D result of a four-gap phenolic Resistive Plate Chamber (RPC) to be applied to high-rate particle triggers in high-energy physics experiments. A prototype four-gap RPC equipped with four 1-mm-thick gaps was constructed with high pressure laminated (HPL) plates, and was tested for cosmic muons and high-rate gamma rays irradiated from a 200 mCi Cs-137 source. A gas mixtures composed of tetrafluoroethane, isobutane, and SF6 were used to figure out the basic characterstics of the four-gap RPC, such as efficiencies, data cluster sizes, charge distributions of the pulses, and the detector property at high-rate backgrounds. In conclusions, the prototype four-gap RPC satisfied the detection capability to signal rates as much as 2 kHz cm^{-2}. Furthermore, the mean fast charge drawn in the prototype four-gap RPC was at least factor 2 smaller than the one drawn in the typical 2-mm thick double-gap RPCs, which would be conductive to reduce possibility of degradation of the gas gaps that would caused by the high-rate particle signals.

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목차

1 Introduction 1
1.1 Double-gap RPCs in CMS 3
1.2 Four-gap RPCs in CMS 5
2 High-Pressure Laminate for four-gap RPCs 6
2.1 Measurement of resistivities for HPL samples 6
2.2 Results of the resistivity test 9
3 High-voltage test for four-gap RPCs 10
3.1 Experimental setup 10
3.1.1 Gas system 10
3.1.2 Setup for cosmic muon tests 10
3.2 Data for cosmic muons and noises 15
3.2.1 Analysis for cosmic muons 15
3.2.2 Analysis for noises 33
4 Test with gamma-ray background 34
4.1 Setup for tests with gamma irradiation 34
4.2 Cosmic muon data with gamma-ray background 34
5 Results 50
6 Conclusion 61
A Example of root code and root macro for analysis in this thesis 62
A.1 Root code for make to root files; - multigap.C 62
A.2 Root macro for muon efficiency and streamer; - eff_st.C 69
A.3 Root macro for charge distributon; - charge_dis.C 79
A.4 Root macro for two dimensional histogram; - charge_time_2d.C 83

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