Meson Production in p+d Collisions and the I=0 π−π Interaction. I. Measured Momentum Spectra of He3 and H3 Nuclei from High-Energy p+d Collisions

Abstract

The momentum spectra of ${\mathrm{He}}^3$ and ${\mathrm{H}}^3$ nuclei produced in $p+d$ collisions have been measured with high resolution. Data were obtained at several angles and incident proton energies of about 745 MeV. Each spectrum exhibits a peak due to single pion production and a continuum due to double pion production. An anomalous bump has been observed in the ${\mathrm{He}}^3$ spectra which we interpret as an $I=0\mathrm{}$ virtual di-pion with a scattering length of 2 ħ/μc. In this series of four papers we summarize the data obtained over a series of three cyclotron runs. The first paper deals with the experiment and techniques, and the second with the results of the measurements on single-pion production. Next we describe an experiment to determine the spin and parity of the anomalous bump, and finally we discuss its interpretation.