Ultra-clean radon-free four cylinder magnetically-coupled piston pump

Abstract: A high performance gas displacement pump based on four individual cylinders was developed. The magnetically-coupled pistons and the hermetically-sealed housings as well as the special cleanliness in terms of out-gassing and radio-purity make the four cylinder pump interesting for the usage in low background experiments dealing with noble gases as target. An optimized inner flow path as well as reduced dead volume with respect to the prototype single cylinder pump of the XENON1T experiment combined with advanced polymer piston gaskets and a piston coupling force of (3177 $\pm$ 162) N ensures a high and reliable performance. Furthermore, a phase-shifted synchronization of the pistons' movement creates an additional performance boost as well as minimizes fluctuations of flow and compression. The pump is able to generate xenon flows of 474 slpm at a pressure difference of 1.80 bar.