A waterfall target for electron scattering experiments

High-resolution hypernuclear spectroscopy at Jefferson Lab, Hall A

“…The high-quality beam, the good spectrometers and the new experimental devices allowed us to obtain very good results. For the first time, measurable strength with sub-MeV energy resolution was observed for the core-excited states of 12 Λ B. A high-quality 16 Λ N hypernuclear spectrum was likewise obtained.…”

“…The use of other oxygen compounds requires additional measurements to subtract the non-oxygen background, whereas the hydrogen in water can be used for calibration purposes. The technique of using continuously flowing water as an electron-scattering target was first developed by Voegler and Friedrich [13], and later refined by Garibaldi et al [12]. The waterfall foil is produced in a cell mounted in the standard scattering chamber.…”

“…All parts in contact with the water are made of stainless steel. Once the target is formed the thickness increases with the pump speed up to a maximum value that depends on the dimension of the slits and the stainless steel poles [12]. A factor of ∼ 3 magnification is possible (see Fig.…”

“…The E94-107 experiment in Hall A at Jefferson Lab [5] started a systematic study of high-resolution hypernuclear spectroscopy on p-shell targets, specifically 9 Be [6], 12 C [7] and 16 O [8]. Moreover a study of the elementary reaction on a proton was performed.…”

“…The experiment E94-107 in Hall A at Jefferson Lab started a systematic study of high resolution hypernuclear spectroscopy in the 0p-shell region of nuclei such as the hypernuclei produced in electroproduction on 9 Be, 12 C and 16 O targets. In order to increase counting rates and provide unambiguous kaon identification two superconducting septum magnets and a ring-imaging Čherenkov detector were added to the Hall A standard equipment.…”