Wide-window gas target system for high resolution experiment with magnetic spectrometer

A gas target system has been developed for nuclear scattering experiments with a highly dispersive spectrometer at small scattering angles including 0°. The system is equipped with a gas cell that has a wide beam window of 44 mm in width and 14 mm in height. The size is sufficient to pass a dispersed beam, which is essential for high energy-resolution measurement. A gas handling system allows target gas that is often limited in quantity, to be collected for reuse. Typical areal density is 1 mg/cm ² for ²⁰Ne or ³⁶Ar gas. The target can be operated either at room temperature or at the liquid nitrogen temperature. The gas target has been employed in a proton inelastic-scattering experiment at 295 MeV with the Grand Raiden spectrometer at the Research Center for Nuclear Physics. A good energy resolution of 20 keV (FWHM) has been achieved at scattering angles of 0-4.5°.