Helium Threshold Cherenkov pressure setting and efficiency

Maximum gas pressure as a function of the beam momentum to select different particles:

6 meter long Cherenkov efficiency as a function of pressure @ 10 GeV/c beam momentum:

6 meter long Cherenkov efficiency as a function of pressure @ 20 GeV/c beam momentum:

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6 meter long Cherenkov efficiency as a function of the beam momentum to select different particles: