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COWAN 1954

Cowan, E.W.;
A V-Decay Event with a Heavy Negative Secondary, and Identification of the Secondary V-Decay Event in a Cascade
Phys. Rev. 94 (1954) 161;

Abstracts
Two cosmic-ray decay events have been photographed in a cloud chamber under conditions that yield mass values from combined magnetic-field momentum measurements and ionization measurements from droplet counting. A method has been developed for assigning meaningful probable errors to the ionization measurements. The first event is interpreted as the decay of a neutral V particle into a positive π meson and a negative particle of mass 1850 ± 250m_e. On the assumption of a two-body decay, the Q value for the decay is 11.7 ± 4 MeV. The second event is a cascade decay that can be summarized by the following reaction: Y^– → 67 ± 12 MeV + π^–Λ^o → 40 ± 13 MeV + π^– p. The proton of the Λ^o decay is identified by a measured mass of 2050 ± 350m_e. On the assumption of a two body decay, the mass of the primary V particle is 2600 ± 34m_e.

Accelerator COSM Detectors CLOUD

Reactions

	Λ p π–
	neutral π+ hadron–
	Ξ– Λ π–

Particles studied

Ξ–

ex, mass

Record comments
Confirmation of Ξ^– cascade decay. First indication for anti-Λ.

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