[en] A detector for ions and metastable atoms has been designed and evaluated which utilizes a conversion from particle to photon detection. The device is ''solar blind'' and currently used in shock-tube research in conjunction with a quadrupole mass spectrometer where the insensitivity of the gain to pressure fluctuations is highly advantageous. Preliminary observations of the performance of the detector and its conversion efficiency for various ion species are reported. Values of overall gain are typically 5 x 10⁵ for conversion electrode potentials of 10 kV and a characteristic time constant less than 1 μsec. (U.S.)