THE INTERACTION OF K$sup -$-MESONS WITH PHOTOGRAPHIC EMULSION NUCLEI. PART II. THE EMISSION OF HYPERONS FROM K$sup -$-INTERACTIONS AT REST (K$sup -$-COLLABORATION)
The emission of SIGMA -hyperons from 3037 K/sup -/ capture stars at rest in nuclear emulsion was studied. The identification of the hyperons is discussed. Charged SIGMA -hyperons were emitted from (17.6 plus or minus 1.0)% of all K/sup -/-stars while (9.6 plus or minus 0.6)% of them lead to the emission of both SIGMA -hyperons and pi -mesons. The SIGMA /sup -// SIGMA / sup +/ ratio for all stars is 0.86 plus or minus 0.12, while for stars in which a pi -meson is also emitted the ratio is 0.45 plus or minus 0.10. The difference between this latter value and the markedly different value (2.0) obtained for K/sup -/-interactions at rest in a hydrogen bubble chamber is attributed to the Fermi motion of nucleons in the nucleus, and a dependence of the relative K/sup -/ transition amplitudes on the energy of relative motion of the K/sup -/meson and nucleon. The branching ratio, R, of the number of SIGMA / sup +/ decays to pi /sup +/ and proton respectively is 1.23 plus or minus 0.27. The stable prong distribution of the stars in which a hyperon is emitted, as well as the energy distribution of the SIGMA -hyperons at emission was studied. About 16% of all identified charged SIGMA -hyperons had an emission energy above 60 Mev, and had to be attributed to multi-nucleon interactions of the K/sup -/- meson. It is estimated that the proportion of all multi-nucleon primary capture processes may be as high as 30 to 40%. From the fraction of SIGMA /sup +/ emitting stars which also emit a pi /sup -/-meson it is concluded that only about 10% of the pi /sup -/-mesons fall to escape from the nucleus in which capture occurs. This could be understood if K/sup -/-capture occurs predominantly in the peripheral region of the nucleus. From a similar study of SIGMA -emitting stars it is found however that the proportion of pi /sup +//sub - / or pi /sup 0/-mesons, or both, that are absorbed in the nucleus is much higher. Estimates are made of the mean free path in nuclear matter of SIGMA -hyperons and pi /sup 0/-mesons. Most of the onenucleon interactions leading to SIGMA - hyperon production take place with protons and the transition amplitudes corresponding to the T = 1 state of isotopic spin is smaller than the T = 0 transition amplitude. (auth)
- Research Organization:
- Univ. of Bristol, Eng.; Universite Libre, Brussels; Inst. for Advanced Studies, Dublin; University College, Dublin; University College, London; Universita, Milan; Istituto Nazionale di Fisica Nucleare, Milan; Universita, Padua
- NSA Number:
- NSA-14-005797
- OSTI ID:
- 4197698
- Journal Information:
- Nuovo Cimento (Italy) Divided into Nuovo Cimento A and Nuovo Cimento B, Vol. Vol: (10) 14; Other Information: Orig. Receipt Date: 31-DEC-60
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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