The weak decay of helium hypernuclei

Thesis/Dissertation · Wed Jan 01 04:00:00 EST 1992

OSTI ID:7271284

Athanas, M J

A [Lambda] hyperon replaces a neutron in a nucleus to form a hypernucleus via the [sup A]X(K[sup [minus]], [pi][sup [minus]])[sup A][sub [Lambda]]X reaction at 750 MeV/c (Brookhaven Experiment 788). The free [Lambda] decay rates [Gamma]([Lambda] [yields] p[pi][sup [minus]]) and [Gamma]([Lambda] [yields] n[pi][sup 0]) are diminished due to Pauli blocking but a non-mesonic decay mode, nucleon stimulated decay N[Lambda] [yields] Nn, is present and is detected via the energetic decay nucleon(s) ([approximately]400MeV/c). Measurements of the various hypernuclear decay rates [Gamma]([Lambda] [yields] p[pi][sup [minus]]), [Gamma]([Lambda] [yields] n[pi][degrees]), [Gamma]([Lambda]n [yields] nn), and [Gamma]([Lambda]p [yields] np) provides insight into the strong modification of the weak interaction such as the baryon-baryon [delta]I = 1/2 rule. The hypernuclear state is isolated by momentum analysis of (K[sup [minus]], [pi][sup [minus]]) target reaction. Out-of-beam large volume scintillation detectors and tracking chambers are used to make particle identification of the hypernuclear decay products by time-of-flight, dE/dx, and range. The kinetic energy of the decay neutrons are measured by time of flight using the large volume 100 element neutron detector system. The hypernuclear lifetime is directly measured using precision scintillator counters and tracking chambers. Measurements of the various decay rates as well as the total lifetime are discussed for [sup 4]He.

• Research Organization: Carnegie-Mellon Univ., Pittsburgh, PA (United States)
• OSTI ID: 7271284
• Country of Publication: United States
• Language: English

Related Subjects

662210 -- Specific Theories & Interaction Models
662360 -- Decays of Baryons-- (1992-)
663110* -- General & Average Properties of Nuclei & Nuclear Energy Levels-- (1992-)
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
BARYONS
BOSONS
DECAY
ELEMENTARY PARTICLES
ELEMENTS
FERMIONS
FLUIDS
GASES
HADRONS
HELIUM
HYPERNUCLEI
HYPERONS
KAONS
KAONS MINUS
LAMBDA BARYONS
MESONS
NONMETALS
NUCLEAR FRAGMENTS
NUCLEI
PIONS
PIONS MINUS
PSEUDOSCALAR MESONS
Pa
Particle Systematics-- Unified Theories & Models-- (1992-)
RARE GASES
STRANGE MESONS
STRANGE PARTICLES