Photoproduction of K^o mesons from protons and from complex nuclei

Abstract

The momenta spectra of neutral K-mesons photoproduced from protons and other nuclei by bremsstrahlung have been measured, for photon energies up to 5 GeV. The cross sections for production of K_L^o from protons integrated over momenta from 1.5 GeV/c to the maximum were 11.8 ± 3.5, 14.0 ± 3.7, 33.4 ± 6.9 and 35.3 ± 7.5 μb/sr/equivalent quantum at $\text{3}\text{1}\text{2}{}^{\mathrm{<mtext>o</mtext>}}$ to bremsstrahlung beams with maximum energies of 3.5, 4.0, 4.5 and 5.0 GeV, respectively. At 9^o the cross sections, similarly defined, were 3.6 ± 3.0 and 6.0 ± 3.5 μb/sr/equivalent quantum at 3.5 and 4.0 GeV, respectively. The cross sections for production from nuclei, at $\text{3}\text{1}\text{2}{}^{\mathrm{o}}$ and with bremsstrahlung of maximum energy 4.5 GeV, were 32.0 ± 8.0, 49.1 ± 6.0 and 45.9 ± 15.7 μb/sr/equivalent quantum per nucleon for Be, Al and Cu, respectively.

The observed spectra cannot be explained in terms of simple processes; the K- are probably produced in association with several other particles.

A description is given of the ferrite core wire spark chambers used in this experiment, including the readout logic and on-line computer system.