A very light and thin liquid hydrogen/deuterium heat pipe target for COSY experiments

A liquid hydrogen/deuterium heat pipe (HP) target is used at the COSY external experiments TOF, GEM and MOMO. The target liquid is produced at a cooled condenser and guided through a central tube assisted by gravitation into the target cell. An aluminum condenser is used instead of copper, which requires less material, improves conductivities and provides shorter cooling down time. Residual condenser temperature fluctuations in the order of ≈0.4 K are reduced by using thermal resistances between the cooling machine and the condenser of the heat pipe combined with a controlled heating power. A new design with only a 7-mm-diameter HP has been developed. The diameter of the condenser part remains at 16 mm to provide enough condensation area. The small amount of material ensures short cooling down times. A cold gas deuterium HP target has been designed and developed which allows protons with energy ?1 MeV to be measured. A 7-mm-diameter HP is used to fill a cooling jacket around the D₂ gas cell with LH₂. The D₂ gas is stabilized at 200 mbar to allow for thin windows. Its density is increased by factor 15 compared to room temperature.