#proportional_counter_tube__proportional_counter  counter tube whose output pulse is proportional to number of ions produced
  supertype:  #counter_tube__countertube  a measuring instrument for counting individual ionizing events
  subtype:  #boron_counter_tube__boroncountertube  a proportional counter tube for counting neutrons

No statement uses or specializes #proportional_counter_tube; click here to add one.