Threshold-Type Cherenkov Counter

This type of IMS A Cherenkov counter module was tested using a 3.5 GeV/c negative pion beam at KEK [10]. TMSA with refractive index is 1.015 and two 2.5 PMTs were arranged. Typical pulse height distributions for 3.5 GeV/c pions and protons observed are 

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Figure 28.7 shows a typical model of a threshold-type Cherenkov counter. Silica aerogel is filled in a box to which photomultiplier tubes (PMTs) are attached. The refractive index of aerogel is set so that the Cherenkov light is emitted for pions but not for kaons [8,9]. In this way, it is known that kaon/pion/proton separation in the momentum region of 1.0-3.5 GeV/c is possible using aerogel with low refractive index such as 1.01-1.03. 

Figure 28.7. Schematic view of a typical threshold-type silica aerogel Cherenkov counter.

A typical single threshold-type aerogel Cherenkov counter (ACC) module looks as shown in Figure 28.12. TMSA tiles are stacked in a thin aluminum box of approximate dimensions 120 x 120 x 120 mm. In order to detect the Cherenkov light effectively, two fine mesh-type PMTs are attached directly to the aerogels at both sides of the box. The inner surface of the box (except for the phototube windows) is lined with a diffuse reflector... 

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