Operation Modes of the KATRIN Experiment Tritium Loop System using $^{83\mathrm{m}}$Kr

TL;DR

This paper discusses the operation modes of the Tritium Loop System in the KATRIN experiment, crucial for calibrating measurements using $^{83 ext{m}}$Kr and ensuring accurate neutrino mass determination.

Contribution

It introduces the technical implementation and performance analysis of special operation modes of the Tritium Loop System for $^{83 ext{m}}$Kr calibration in KATRIN.

Findings

Achieved stable $^{83 ext{m}}$Kr rates suitable for calibration.

Optimized gas densities and compositions in the WGTS.

Demonstrated reliable operation modes for systematic investigations.

Abstract

The KArlsruhe TRItium Neutrino (KATRIN) experiment aims to search for the effective electron antineutrino mass with a sensitivity of 0.2 eV (90 % C.L.). In order to achieve this goal, KATRIN measurement phases focusing on the neutrino mass search are alternated with phases of investigations of systematic effects. During these phases, metastable $^{83\mathrm{m}}$Kr is used as a calibration source. The monoenergetic conversion electrons emitted accompanying the decay of $^{83\mathrm{m}}$Kr allow a direct access to the starting conditions of $\beta$-electrons produced inside the windowless gaseous tritium source (WGTS) of KATRIN. To make use of $^{83\mathrm{m}}$Kr in the WGTS, the Tritium Loop System, which provides a stable flow of tritium to the WGTS, needs to be operated in special modes. This paper focuses on the technical implementation of these modes and their performance with regard to the achievable $^{83\mathrm{m}}$Kr-rates, gas densities, and gas compositions inside the WGTS.