Abstract: The nucleon(N) is a composite particle consisting of three quarks. When a photon(gamma) or a pi meson is absorbed by one of the quarks inside the nucleon, the quark spin is flipped. This results in a change from a spin and isospin 1/2 nucleon into a spin and isospin 3/2 particle called a Delta.

The Delta is an unstable particle. It decays into either a pion-nucleon (pi N) state or a photon-nucleon(gamma N) state.  The purpose of this work is to investigate how these Delta mechanisms determine the photoproduction of pions on the deuteron(d) reactions.

There are four main  mechanisms for the gamma d --> pi NN reaction.  This research focused primaraly on the gamma + d --> Delta N, then the Delta decays into a pion which interacts with the nucleon, creating another Delta, finally resulting in pi N N.  

The differential cross-section of that reaction can then be calculated from the above production amplitude.  This must then be combined with the other mechanisms to be compared with experiment.  This has yet to be done.