Search for the H Dibaryon (S = -2) Using Diffraction Dissociation

The observed hadrons are understood as bound states of three quarks (baryons) or of quarks and antiquarks (mesons). To date no six quark bound state other than the loosely bound deuteron has been observed. Quantum Chromodynamics permits other color-singlet bound states of quarks, and a number of phenomenological models extended from the baryon (q3) and meson (q(bar q)) sectors predict bound six quark states (q6). The most probable candidate is the H dibaryon, composed of two each of the lightest three quarks (udsuds), with quantum numbers JP = 0+, I = 0 and S = -2. Its mass would likely be between the deuteron mass and twice the Λ (uds) mass. This dissertation describes a search for the H dibaryon conducted in a neutral beam at the Brookhaven National Laboratory's Alternating Gradient Synchrotron. In the experiment a 24.1 GeV/c proton beam struck a 1.35 interaction length platinum target producing a collimated neutral beam (62 μsr at 65 mrad from the incident proton direction) which propagated through a 18 m vacuum decay tank before entering a double arm spectrometer. Approximately 20 m from the production target a 10 cm (0.15 interaction length) long active scintillator dissociator was placed in the beam