Regeneration ofK10Mesons and theK10−K20Mass Difference

Abstract

We have studied the regeneration of $K_1^{}{}_{}{}^0$ mesons using a beam of $K_2^{}{}_{}{}^0$ mesons produced at the Brook-haven AGS. The $K_1^{}{}_{}{}^0$ mesons were detected with a pair of magnet-spark-chamber spectrometers that momentum-analyzed the two decay pions. A test of the coherence of the transmission regeneration is made by comparing the yields from half- and full-density copper regenerators. The $K_1^{}{}_{}{}^0-K_2^{}{}_{}{}^0$ mass difference was measured with a regenerator consisting of two pieces of copper separated by a variable air gap. This method is independent of all nuclear scattering parameters and yields a mass difference of 0.50±0.10 in units of $\frac{\hslash }{{\tau }_1}$ (where ${\tau }_1$ is the $K_1^{}{}_{}{}^0$ mean life). Data taken with single copper regenerators of various thicknesses yield mass differences consistent with this measurement. Mass differences larger than 1.0 are strongly rejected by our data. The forward regeneration cross sections for C, Cu, Fe, and W were measured and found to agree with optical-model calculations. Regeneration in liquid hydrogen was also investigated and the results compared with theoretical predictions.