The channeltron

At the end of the setup we detect the particles that have come through with a channeltron. The channeltron has a sensitive surface of a circle of 2.5 mm radius, but this surface is covered with a 5 mm by 40 $\mu$m vertical slit. The channeltron is placed on a horizontal translator, so we can make a horizontal scan of the beam. The front of the channeltron is put on a negative voltage. If a particle hits the front of the channeltron, electrons are released that will enter the channeltron due to the negative voltage. These electrons will release new electrons, and at the end the cascade of electrons can be detected. This can be done by counting pulses, or by measuring the current through the channeltron. The channeltron is able to detect ($2^1$S) Helium atoms, metastable Helium atoms and photons.