Magnetically-coupled piston pump for high-purity gas applications

Experiments based on noble elements such as gaseous or liquid argon or xenon utilize the ionization and scintillation properties of the target materials to detect radiation-induced recoils. A requirement for high light and charge yields is to reduce electronegative impurities well below the ppb level. To achieve this, the target material is continuously circulated in the gas phase through a purifier and returned to the detector. Additionally, the low backgrounds necessary dictate low-Rn-emanation rates from all components that contact the gas. Since commercial pumps often introduce electronegative impurities from lubricants on internal components or through small air leaks, and are not designed to meet the radiopurity requirements, custom-built pumps are an advantageous alternative. A new pump has been developed in Muenster in cooperation with the nEXO group at Stanford University and the nEXO/XENON group at Rensselaer Polytechnic Institute based on a magnetically-coupled piston in a hermetically sealed low-Rn-emanating vessel. This pump delivers high performance for noble gases, reaching more than 210 standard liters per minute (slpm) with argon and more than 170 slpm with xenon while maintaining a compression of up to 1.9 bar, demonstrating its capability for noble gas detectors and other applications requiring high standards of gas purity.Comment: 11 pages, 18 figure

A multi-PMT Optical Module for the IceCube Upgrade

Following the first observation of an astrophysical high-energy neutrino flux with the IceCubeNeutrino Observatory in 2013 and the identification of a first cosmic high-energy neutrinosource in 2017, the detector will be upgraded with about 700 new advanced optical sensors.This will expand IceCube’s capabilities both at low and high neutrino energies. A large fractionof the upgrade modules will be multi-PMT Digital Optical Modules, mDOMs, each featuring24 three-inch class photomultiplier tubes (PMTs) pointing uniformly in all directions, therebyproviding an almost homogeneous angular coverage. The signal from each PMT is digitizedindividually, providing directional information for the incident photons. Together, the 24 PMTsprovide an effective photosensitive area more than twice than that of the current IceCube opticalmodule. The main mDOM design challenges arise from the constraints on the module size andpower needed for the 24-channel high-voltage and readout systems. This contribution presentsan mDOM design that meets these challenges and discusses the sensitivities expected from thesemodules

First operation of the KATRIN experiment with tritium

The determination of the neutrino mass is one of the major challenges in astroparticle physics today. Direct neutrino mass experiments, based solely on the kinematics of β β -decay, provide a largely model-independent probe to the neutrino mass scale. The Karlsruhe Tritium Neutrino (KATRIN) experiment is designed to directly measure the effective electron antineutrino mass with a sensitivity of 0.2 eV 0.2 eV (90% 90% CL). In this work we report on the first operation of KATRIN with tritium which took place in 2018. During this commissioning phase of the tritium circulation system, excellent agreement of the theoretical prediction with the recorded spectra was found and stable conditions over a time period of 13 days could be established. These results are an essential prerequisite for the subsequent neutrino mass measurements with KATRIN in 2019