Proton Trajectory Assay - Recoil Telescope (PAJARITO) background study on Sandia Z-pinch Facility

The Los Alamos National Laboratory team has led design and validation efforts for a proton recoil telescope for application to experiments at the Z machine at Sandia, for measurement of nuclear reaction history and ultimately resolution of the neutron energy spectrum. This effort has focused on the feasibility of the diagnostic measurement at the yield levels produced by current Z platforms, which amounts to the question of the signal-to-noise ratio that can be obtained. In experiments at Z, there is expected to be significant background signal in terms of the x-ray and gamma ray radiation which is known to be emitted by strongly imploded targets, so the signal-to-noise ratio is described here as a signal-to-background ratio, and ways are sought to maximize the system and detector sensitivity to the recoil protons (signal) and decrease sensitivity to the x-ray and gamma photon emission (background). The Proton Trajectory Assay - Recoil Telescope (PAJARITO) is a diagnostic method to characterize particle beams, making use of the scattering interaction of the beam with an inserted target foil. An approach is being pursued to empirically obtain measurements of the background signal level on candidate detectors in a representative PAJARITO geometry, which can then be used to benchmark radiation MC models and inform the instrument design. This PAJARITO Test Bed has been designed and was fielded on the Z center section in the summer of 2022. The design, integration, and preliminary in-situ measurements of the gamma/x-ray background will be presented.

LA-UR-22-26572