Method and apparatus for detecting hydrogen-containing compounds

A low-cost detector of hydrogen-containing compounds in gas or thin-film samples (10) is disclosed. The device preferably includes an alpha particle source (1), an energy degrading medium (13), a charged particle detector (e.g. a solid state diode detector) (7), and amplification (16), threshold (19), logic (22), timing (25) circuits, humidity correction apparatus (28), and alarm/display circuit (31). The invention relies upon the use of the energy degrading foil (13) to pass selectively certain particles. Energetic alpha particles from a radioactive source (1) enter the sample (10) and hydrogen nuclei, or protons, elastically scattered by alpha particles, are able to penetrate the energy degrading foil (13) which is thick enough to stop the alpha particles (4). The protons are detected and a suitable output signal can be produced to provide an accurate measure of the quantity of hydrogen in the gas or thin-film sample. The hydrogen detector can be combined with a smoke detector to produce an apparatus capable of detecting both smoke and hydrogen. This technology can also be used to reduce noise and block light penetration in a radon detection application.