This is the first of a series of experiments designed to take advantage of the extension of the peak energy of the Caltech electron synchrotron into the 1500 mev region to measure K-photoproduction in hydrogen at energies significantly above threshold. Data on both the γ + p → K^+ + Λ° and the γ + p → K^ + Σ° reactions were obtained for photon energies from 1000 to 1400 mev and center of momentum angles near 125°.At the low energy limit of these measurements agreement is found with earlier measurements in this laboratory and at Cornell. In the 1100 to 1400 mev region the K^+ + Λ° differential production cross section appears to level off at a value of about 1.2 x 10^(-31) cm^2 / steradian or possibly decrease slightly. The three K^+ + Σ° points taken continue the steep rise above threshold observed earlier at Cornell and then appear to drop off above 1250 mev.
The experiment was performed by allowing the K^+ particles produced in a liquid hydrogen target by the incident photon beam to pass through a symmetric wedge magnet, which focused the particles of the proper momentum onto a scintillation counter telescope in which they came to rest. In this way, the momentum, range, and specific ionization loss of each particle passing through the system was determined. To discriminate against the much more numerous pions and protons present, the velocity of each particle was measured by using time of flight techniques.
