Synchrotron Radiation Facilities for Biological Use at the Institute for Solid State Physics and Photon Factory

Abstract

Irradiation experiments at the Synchrotron Radiation Laboratory (SRL), Institute for Solid State Physics (ISSP) began over 10 years ago. The experiments started in the fall of 1977 with white synchrotron radiation from the electron storage ring called INS-SOR that was operated at 0.38 GeV. The first group of biological materials used was Bacillus subtilis spores and yeast cells. The synchrotron radiation was extracted through the MgF2 window installed at the end of vacuum line of the storage ring, and was introduced into the vacuum irradiation chamber connected to it. The surprisingly short irradiation time required to get a significant biological effect prompted us to construct a monochromator system, especially in the vacuum-UV (VUV) region. In 1980 we installed a 2.2 m Wadsworth mount monochromator along with some accessories for the measurement of photon intensity. Surprised by a rapid deterioration of optical elements, so that there was insufficient time to perform our experiments, we inserted a pre-mirror chamber that houses two mirrors to remove unnecessary short wavelength radiation before reaching the monochromator. We found later that the most critical factor is the vacuum. After a period of trial and error, we were satisfied with a small-scale improvement for performing irradiation experiments in the wavelength range from 150 to 250 nm (Ito et al., 1984). Several important contributions in VUV photobiology were made with this arrangement.