High-Energy Bremsstrahlung from a Silicon Single Crystal

Results are given from several measurements on bremsstrahlung from a silicon crystal. The silicon crystal is a half-circular plate 15 mm in diameter and 2 7 x 10/sup -3/ radiation lengths in thickness; it is cut perpendicular to the axis STA111! within plus or minus 4 mrad, as determined by a Laue x-ray back- reflection method. The crystal could be rotated about a horizontal and a vertical axis; the precision of angle measurements is plus or minus 0.5 mrad. Intensities of bremsstrahlung produced in a Si single crystal (T = 293 deg K) are given as a function of theta , the angle between the 1-Bev electron beam and the crystal axis, and as a function of the fractional energy of the photon with respect to the electron energy. A central minimum is shown to exist in the plot of the bremsstrahlung intensity and theta , whereas this condition was not shown to exist in previous experiments. It is believed that this is due to insufficient angular resolution with respect to the how-energy detected photons. (B.O.G.)