Design and performance of a two arm wire chamber spectrometer for use at the Manitoba 50 MeV cyclotron

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McKeown, Joseph.
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A wire chamber spectrometer connected on-line to a PDP-9 and an IBM 360/65 computer has been developed to study (p,2p) reactions at incident energies in the range 30-50 MeV. It consists of two pairs of wire chambers, one pair on each side of the incident beam. Outgoing protons are detected in coincidence in large plastic scintillation counters, subtending solid angles as large as 0.16 sterad. at the centre of the target. As the events arrive, the PDP-9 calculates the proton trajectories and projects them into the target volume. When a gaseous target is employed so that the reaction volume is long in the beam direction, most chance coincidences and slit-scattered protons are rejected by testing for anevent vertex. If a vertex is made, then the event pulse heights and coordinates are sent to the IBM 360/65, where the full kinematic analysis is performed. For a pair of 21.0 MeV outgoing protons the energy resolution of the undetected third particle is 1.5 MeV HWHM and the angular resolution of each arm is 0.32* HWHM. From the data collected during a test run preliminary results are presented on the application of the spectrometer to a study of the D(p,2p)N reaction and the proton-proton bremsstrahlung process.