J. M. Watson

Measurement of the

Data from the reaction ..pi../sup -/p ..-->.. nK/sub s//sup 0/K/sub s//sup 0/ have been used to determine the cross section for the reaction ..pi../sup +/..pi../sup -/ ..-->.. K/sub s//sup 0/K/sub s//sup 0/ by extrapolation to the pion pole. The reaction ..pi../sup +/..pi../sup -/ ..-->.. K/sub s//sup 0/K/sub s//sup 0/ is dominated by S* and f/sup 0/ production. The ..pi../sup +/..pi../sup -/ ..-->.. K/sub s//sup 0/K/sub s//sup 0/ cross section is well below the S-wave unitarity limit in the S* (threshold) region. We discuss implications for the SU(3) scalar meson nonet and for ..pi pi.. phase-shift analyses.

\pi^+ \pi^- \to K^0_S K^0_S

Data from the reaction ..pi../sup -/p ..-->.. nK/sub s//sup 0/K/sub s//sup 0/ have been used to determine the cross section for the reaction ..pi../sup +/..pi../sup -/ ..-->.. K/sub s//sup 0/K/sub s//sup 0/ by extrapolation to the pion pole. The reaction ..pi../sup +/..pi../sup -/ ..-->.. K/sub s//sup 0/K/sub s//sup 0/ is dominated by S* and f/sup 0/ production. The ..pi../sup +/..pi../sup -/ ..-->.. K/sub s//sup 0/K/sub s//sup 0/ cross section is well below the S-wave unitarity limit in the S* (threshold) region. We discuss implications for the SU(3) scalar meson nonet and for ..pi pi.. phase-shift analyses.

Scattering Cross-section

Abstract Construction details and calibration techniques used in the implementation of a large lead-glass hodoscope are described. The algorithms used to determine the position and energy of the incident photons as well as the energy and position resolution are discussed.

Measurement of the. pi. /sup +/. pi. /sup -/. -->. K/sub s//sup 0/K/sub s//sup 0/ scattering cross section

This paper describes the results of an experiment studying the reaction π+p → Δ++π0π0 using the Argonne National Laboratory 1.5 m streamer chamber combined with a lead glass hodoscope. The results of an energy‐independent amplitude analysis from threshold to 2.3 GeV are presented. In this analysis the f0(1270), the h0(2040), and a JP=2+ state at 1.8 GeV with a width of 0.280 GeV are observed. The amplitude ambiguity arising from analyses of π+π− → π+π− data in the 1.6 GeV region is resolved in favor of the β‐type solution. An energy‐dependent S‐wave phase shift analysis from 1.0 to 1.5 GeV is presented.

A highly segmented lead-glass hodoscope for detection of multiple photon final states

The ..lambda lambda..-bar system produced in the reaction ..pi../sup -/p..-->..n..lambda..Lambda-bar at 6.0 and 7.0 GeV/c has been studied utilizing the ANL1.5-m streamer-chamber facility. A 400 000-photograph exposure yielded 284 unweighted n..lambda..Lambda-bar events. The cross section for the reaction is 0.51 +- 0.22 ..mu..b at 6.0 GeV/c and 1.21 +- 0.23 ..mu..b at 7.0 GeV/c. No significant indications of baryonium states decaying into ..lambda..Lambda-bar are found.

Light quark spectroscopy and ππ phase shifts from the reaction π+p → Δ++π0π0 at 8.0 GeV/c

Characteristics of the reaction π+ p→Δ++π0π0 at 8 GeV/c are presented. The sample consists of some 27, 000 events for which mass spectra, t‐distributions, and ππ angular distributions are presented. The π0π0 mass spectrum rules out the ’’narrow e (700)’’ solution for the ππ S0 phase shift. Data in the 1300 MeV region show substantial S‐D wave interference.