A DOUBLE MIRROR W C MULTILAYER MONOCHROMATOR FOR RADIATION BIOLOGY APPLICATIONS/

A double-mirror multilayer monochromator was developed for the purpose of irradiating live cell cultures at the Synchrotron Radiation Center , University of Wisconsin-Madison. The monochromator is designed for t he soft x-ray region with photon energies between 270 and 2400 eV. Mul tilayer mirrors with 55 bilayers of W/C and a bilayer spacing of d=3.0 nm are sputter deposited on Si substrates. By proper masking of the s puttering sources, variation in the bilayer spacing over the area of t he mirror is minimized. The uniformity of the bilayer spacing was meas ured to be Delta d/d<1%, over the 75 mmX25 mm area of the mirrors. The reflectivity was measured as a function of energy to determine the in tegrated reflectivity and evaluate the contribution of the specular re flection and higher orders to the monochromatic beam. The use of suita ble filters with a Si(Li) detector allows determination of the spectra l output of the monochromator. The output power of the monochromator b etween 270 and 2400 eV is measured. The resolution of the monochromato r is Delta lambda/lambda=0.04. Applications of the monochromator to ra diation biology are discussed. (C) 1998 American Association of Physic ists in Medicine.