Pion absorption by helium nucleus at delta-resonance

Thesis/Dissertation · Sun Jan 01 04:00:00 EST 1989

OSTI ID:5129682

Mukhopadhyay, S

This thesis studies the non-radiative absorption of charged pions by {sup 3}He at the incident pion energy of 165 MeV. The absorption process is a nuclear reaction in which the pion loses all of its energy, including its rest mass, to the absorbing nucleus. The motivation of the experiment was (a) to study the effect of isospin on pion absorption, (b) to study and compare the absorption by a two-body system (where the third nucleon in {sup 3}He remains as a spectator) as opposed to that on a three-body system (where all nucleons share the available energy). Data were taken at higher pion energies in order to study the energy dependence of the absorption. This thesis presents data obtained from Experiment 705 performed at LAMPF in Los Alamos. The reactions {sup 3}He({pi}{sup +},pp)p and {sup 3}He ({pi}{sup {minus}},pn)n were studied by detecting either two protons or a neutron-proton pair in coincidence. The angular correlation between the emerging nucleons exhibited a strong peak at 180{degree} in their center of mass (called conjugate angles in the laboratory). A sharp peak in the momentum distribution of both the particles is seen corresponding to very low recoil momentum of the third particle. This peak is due to a two-body absorption mechanism, often called quasi-deuteron absorption. A large isospin dependence is observed in the two-body absorption. The ({pi}{sup +},pn) reaction is symmetric about 90{degree} in the two nucleon center of mass, while the ({pi}{sup {minus}},pn) reaction is asymmetric, peaking at the backward angles. The total two-body cross sections for {pi}{sup +} and {pi}{sup {minus}} absorptions are 16.4 {plus minus} 1.5 mb and 0.91 {plus minus} 0.2 mb, respectively.

• Research Organization: Northwestern Univ., Evanston, IL (United States)
• OSTI ID: 5129682
• Country of Publication: United States
• Language: English

Related Subjects

651220* -- Nuclear Properties & Reactions
A=1-5
Experimental
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ABSORPTION
ACCELERATORS
CAPTURE
CHARGED-PARTICLE REACTIONS
COINCIDENCE METHODS
COUNTING TECHNIQUES
CROSS SECTIONS
DATA
EXPERIMENTAL DATA
HADRON REACTIONS
HELIUM 3 TARGET
INFORMATION
ISOSPIN
LAMPF LINAC
LINEAR ACCELERATORS
MAGNETIC SPECTROMETERS
MANY-BODY PROBLEM
MEASURING INSTRUMENTS
MESON FACTORIES
MESON REACTIONS
NUCLEAR REACTIONS
NUMERICAL DATA
PARTICLE PROPERTIES
PHOSPHORS
PION MINUS REACTIONS
PION PLUS REACTIONS
PION REACTIONS
PLASTIC SCINTILLATORS
SPECTROMETERS
TARGETS
THREE-BODY PROBLEM
TIME-OF-FLIGHT METHOD
TOTAL CROSS SECTIONS
TWO-BODY PROBLEM