The cosmic ray has by now has passed through the 16 modules, leaving the Ne-He gas ionised.
On exiting the chamber the cosmic ray passes through the second scintillator counter, which like the first counter, emits a photon which is detected by the phototube, which then converts the light pulse into an analogue signal. This signal is then passed through the discriminator which converts the signal into a digital one. The signal will then pass into the coincidence unit.
The coincidence unit gives an output when it receives the digital signals from the two discriminators within a certain time interval. These essentially simultaneous signals indicate the passage of a charged particle through the spark chamber.
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Continue to stage 3
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