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CHARGE-EXCHANGE PRODUCTION OF ANTINEUTRONS AND THEIR ANNIHILATION IN HYDROGEN (thesis)

Technical Report ·
OSTI ID:4044022
A separated beam of antiprotons was sent into the 72-in. hydrogen bubble chamber. The charge exchange of antiprotons into antineutrons and the subsequent annihilation of the antineutrons were observed. The antiprotons were produced internally in the Bevatron; channeled externally by collimation, quadrupole focusing magnets, and bending magnets, and separated from other negatively charged particles by a system of three velocity spectrometers. The antiproton kinetic energy was 950 Mev. Three chargeexchange reactions were studied: (1) p- bar + p yields n-bar + n; (2) p-bar + p yields n-bar + n + pi /sup 0/; and (3) p-bar + p yields n-bar + p + pi /sup -/. The cros s section obtained for Reaction (1) plus Reaction (2) was 7.82 plus or minus 0.55 mb. That found for Reaction (3) was 0.99 plus or minus 0.24 mb, implying on the basis of the statistical-model alone a similar value for reaction (2). The angular differential cross section for Reaction (1) was strongly peaked forward with a value at zero degrees of 4.6 plus or minus 0.5 mb/sr. However, the 13% contamination from Reaction (2) was included. Onehundred and twenty-two of the antineutrons from Reaction (1) and (2) annihilated in the chamber, giving an annihilation cross section of 45.2 plus or minus 5.4 mb. The average chargedpion multiplicity in antineutron annihilation was found to be 3-5 plus or minus 0.3, implying the total pion multiplicity was 5.2 plus or minus 0.4. The ratio of the number of annihilations containing five charged pions to the number containing three charged pions, and the momentum distribution of the pions, were compared with predictions of the statistical model. This model used the covariant phase-space integrals first proposed by Srivastava and Saidarshan and modified by Neuman, and the branching ratios given by Pais. Reasonable agreement was obtained for a volume five times that of a sphere with a radius of one pion Compton wavelength. Three events were observed that fitted K/sup 0/ - meson production in antineutron annihilation. (auth)
Research Organization:
California. Univ., Berkeley. Lawrence Radiation Lab.
DOE Contract Number:
W-7405-ENG-48
NSA Number:
NSA-15-022913
OSTI ID:
4044022
Report Number(s):
UCRL-9589
Country of Publication:
United States
Language:
English

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PHYSICS