Accelerator internal target experiments using a supersonic gas jet

Abstract

Internal gas jet targets allow a high degree of flexibility in the design of experiments to study beam-target interactions in circular accelerators. Ultra-thin targets in the range 1–100 ng/cm 2 can be produced at essentially any available beam energy. Since the beam passes through the target approximately 10 5 times per second, the effective target thickness can be comparable to that of a typical thin foil. We have performed a number of experiments at both FNAL and the Brookhaven AGS utilizing mixed and pure gas jet targets to study proton-nucleus collisions. With thousands of hours of experience using a variety of pure and mixed gas targets, we have demonstrated that such a target facility is not only readily adapted to the physical constraints of the accelerator but also offers a wide choice of targets and detector array possibilities. In addition, a target normalization technique is presented utilizing p-p elastic scattering from the hydrogen component of the mixed gas targets.