Patent ID: 7812614

Claim:
A nonradiative electron capture detector, comprising: a discharge chamber having a needle-like electrode and a ring-shaped electrode opposed to each other and configured to introduce helium thereinto as discharge gas to generate a DC type glow discharge between the needle-like electrode and the ring-shaped electrode, with a transport tube for transporting positively and negatively charged particles and metastable helium generated in the discharge chamber being connected to the discharge chamber; a dopant-gas supply mechanism connected to the transport tube, and supplying dopant gas having an ionization energy lower than an emission energy of the metastable helium; a mechanism including positive and negative electrodes, and measuring a current; and a detecting unit measuring the current whose carriers are free electrons and positive ions generated by Penning ionization caused by a collision between the metastable helium and the dopant gas, wherein Penning gas comprised of organic gas lower in ionization potential than dopant is caused to coexist with the dopant gas, and an isolation distance between the needle-like electrode and the ring-shaped electrode is 10 to 30 times larger than an inside diameter of the detecting unit.