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Calorimetric Wire Detector for Non-Disruptive Atomic Hydrogen Beam Measurement
A minimally disruptive detector that measures an atomic hydrogen beam by stringing a thin gold-coated tungsten wire across it: atoms stick and recombine into molecules on the wire, releasing bond energy that slightly heats the wire and raises its electrical resistance, which is read out as a voltage change. Students learn how translating the wire across the beam maps its angular distribution, how an analytic thermal-source beam model is fit to the data, and why a thin-wire calorimeter is advantageous over a quadrupole mass spectrometer in high magnetic fields and confined spaces.