Bonn 2020 – scientific programme
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HK: Fachverband Physik der Hadronen und Kerne
HK 59: Structure and Dynamics of Nuclei X
HK 59.4: Talk
Friday, April 3, 2020, 12:00–12:15, J-HS E
Extreme high vacuum for the PUMA trap — •Erik Friedrich1, José António Ferreira Somoza2, Paolo Chiggiato2, Audric Husson1, Wojciech Kubinski1, Noritsugu Nakatsuka1, Alexandre Obertelli1, and Frank Wienholtz1 for the PUMA collaboration — 1Technische Universität Darmstadt, Darmstadt, Germany — 2CERN, Geneva, Switzerland
The antiProton Unstable Matter Annihilation (PUMA) project targets to study short-lived nuclei with antiprotons at CERN. The technical challenge of PUMA is to store approximately one billion antiprotons for at least a month and transport them from the ELENA low-energy antiproton ring to the ISOLDE radioactive-ion beam facility at CERN. For this long-term storage, an extremely high vacuum (XHV) of about 10−17 mbar, corresponding to a gas density about 20 cm−3, should be achieved by cryopumping. The residual gas density at XHV region depends on the molecular occupation of hydrogen on the cryogenic surface. The key parameter to simulate this process is so-called the hydrogen isotherms at XHV. The specificity of the PUMA experiment is that the cryopumped region should be open to the beam line for the introduction of low-energy (few keV) ions into the PUMA device. The presentation reports on the vacuum cryostat of PUMA and summaries the simulations with Molflow+ and COMSOL Multiphysics to optimize the cryostat design. In addition, the development of a cryogenic gate valve is described.