Accession Number : AD0604581

Title :   A STUDY OF DI-PION RESONANCES PRODUCED AT LOW MOMENTUM TRANSFER IN NEGATIVE PION + P YIELDS NEGATIVE PION + POSITIVE PION + N AT 1.6 BEV/C.

Descriptive Note : Technical rept. no. 35,

Corporate Author : PRINCETON UNIV N J ELEMENTARY PARTICLES LAB

Personal Author(s) : Clark,Alan R.

Report Date : 28 AUG 1964

Pagination or Media Count : 118

Abstract : Spark chamber spectrometers were used to investigate the di-pion mass spectrum over the mass range 450 1000 MeV. The di-pions were produced in the reaction negative pion + p yields negative pion + positive pion + n at an incident momentum of 1.6 BeV/c. More than 600 events were obtained with a mass resolution of = 4 MeV. The di-pion mass spectrum shows a strong contribution from the neutral RHO meson centered at approx. 740 MeV with a width on the order of 130 MeV. There is no evidence of any other structure in the spectrum. The data can be interpreted fairly well within the framework of the one pion exchange model (OPE), but the distributions of the Treiman-Yang angle and the pion-neutron effective masses indicate the presence of non-OPE processes. The distributions could be explained by the formation of a recently reported I = 1/2 pion-N state with a mass of 1.4 BeV. Comparisons with other measurements of the total cross section show a much larger resonant contribution to the data than expected from OPE; this effect can be explained by a depolarization of approx. 35% of the rho meson due to rho-N final state absorption.

Descriptors :   (*PIONS, NUCLEAR REACTIONS), (*MESON REACTIONS, NUCLEAR RESONANCE), MASS SPECTROSCOPY, MOMENTUM, PROTON REACTIONS, NEUTRONS, MESON SCATTERING, MESON CROSS SECTIONS, NUCLEONS, ABSORPTION, NUCLEAR SPINS

Distribution Statement : APPROVED FOR PUBLIC RELEASE