Cryopanel and fast closing valve system for ISOL beam operation

We designed a cryopanel system based on Molflow+ simulation and constructed for installation in a beam line of 70 MeV H- cyclotron to adsorb back streaming radioactive molecules from ISOL target. Since the target assembly is not hermetically sealed, a target leak can occur especially during high-power beam operation. The cryopanel surrounds the beam path to enhance adsorption efficiency and can be kept at temperature as low as 10 K. A beam test carried out at a current of ∼1 µA showed the panel temperature is not affected by beam pass. The vacuum in the panel region improves to better than 1 × 10-7 mbar so residual gas spectrum has a low background in detection of target leak. As part of the safety system against target damage, a fast closing valve is installed. These safety systems have been tested as essential components for radiation protection in ISOL operation.