#ionization_chamber__ionization_tube  a measuring instrument that measures the amount of ionizing radiation
  supertype:  measuring_instrument__measuringinstrument__measuring_system__measuringsystem__measuring_device__measuringdevice  instrument that shows the extent or amount or quantity or degree of something
  subtype:  boron_chamber__boronchamber  an ionization chamber lined with boron or filled with boron trifluoride gas for counting low velocity neutrons
  subtype:  Geiger_tube__Geiger-Muller_tube  an ionization chamber contained in a tube in a Geiger counter

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