Development of an isolated compact liquid-hydrogen target for radioactive ion beam experiments

We have developed a liquid-hydrogen target system in a compact geometry with surrounding charged-particle detector arrays. In this design, the target cell was positioned downstream of and thermally isolated from the cryogenic cold head. The cell has a diameter of 46 mm and a thickness of 15 mm. For cooling, a large-volume condenser is introduced as an intermediate stage between the cold head and the target cell, enabling a liquefaction-evaporation circulation of hydrogen. The target system was used in an experimental study using a 10 Be ( p , p d ) beam at the SAMURAI spectrometer at RIKEN. Stable operation was achieved over a ten-day beam time, with a target temperature of around 20 K and a pressures of 1000 hPa.