PHOTOPRODUCTION OF 42.4 Mev POSITIVE PIONS FROM HYDROGEN AT LABORATORY ANGLES BETWEEN 50 AND 170 DEGREES. Technical Report No. 40

Technical Report · Sun Jul 01 04:00:00 EDT 1962

OSTI ID:4801684

Baum, P M; Robinson, C S

Relative differential cross sections for the photoproduc tion of 42.4 Mev pi /sup +/ mesons from hydrogen were measured at twelve laboratory angles between 50 deg and 170 deg . The mesohs were produced in a liquid hydrogen target which was irradiated by the bremsstrahlung beam of a 300 Mev betatron. The pions were momentum-selected by a magnetic spectrometer and detected and counted by a scintillation counter telescope. Since the pion energy was held constant with angle, several types of errors which vary systematically with angle were avoided. The relative cross sections were measured to about 1 per cent statistical accuracy. Possible systematic errors are less than 3 per cent. The experimental cross sections obtained are compared with the predictions of the dispersion theory of Chew, Goldberger, Low, and Nambu, (CGLN). It is found that an appreciable discrepancy exists. When the experimental results are normalized to the theoretical cross section at the smallest angle, the theoretical values at large angles are about 28 per cent higher than the experi mental values. This experimental behavior can be predicted by the inclusion of the rho-meson, or bipion, interaction in the photoproduction amplitude. Comparison with the theoretical resuits of McKinley shows that the data can be fitted quite well by using a rho-meson coupling constant DELTA /ef = -1.2 plus or minus 0.4. The uncertainty in DELTA is due to the uncertainty in the phase shifts appearing in the photoproduction amplitude. (auth)

• Research Organization: Illinois. Univ., Urbana. Physics Research Lab.
• NSA Number: NSA-16-029658
• OSTI ID: 4801684
• Report Number(s): NP-11992
• Country of Publication: United States
• Language: English

Related Subjects

BETATRONS
BREMSSTRAHLUNG
COINCIDENCE METHODS
COUPLING CONSTANTS
CROSS SECTIONS
DISPERSION THEORY
ENERGY
ENERGY RANGE
ERRORS
HYDROGEN
INTERACTIONS
IRRADIATION
MAGNETIC FIELDS
MEASURED VALUES
MESONS
MOMENTUM
PHOTOPRODUCTION
PHYSICS
PIONS
PIONS-PLUS
QUANTUM MECHANICS
RESONANCE
RHO RESONANCES
SCINTILLATION COUNTERS
SPECTROMETERS