Quantitative Long-Term Monitoring of the Circulating Gases in the KATRIN Experiment Using Raman Spectroscopy

The Karlsruhe Tritium Neutrino (KATRIN) experiment aims at measuring the effective electron neutrino mass with a sensitivity of 0.2 eV/c2, i.e., improving on previous measurements by an order of magnitude. Neutrino mass data taking with KATRIN commenced in early 2019, and after only a few weeks of data recording, analysis of these data showed the success of KATRIN, improving on the known neutrino mass limit by a factor of about two. This success very much could be ascribed to the fact that most of the system components met, or even surpassed, the required specifications during long-term operation. Here, we report on the performance of the laser Raman (LARA) monitoring system which provides continuous high-precision information on the gas composition injected into the experiment’s windowless gaseous tritium source (WGTS), specifically on its isotopic purity of tritium—one of the key parameters required in the derivation of the electron neutrino mass. The concentrations cx for all six hydrogen isotopologues were monitored simultaneously, with a measurement precision for individual components of the order 10−3 or better throughout the complete KATRIN data taking campaigns to date. From these, the tritium purity, εT, is derived with precision of <10−3 and trueness of <3 × 10−3, being within and surpassing the actual requirements for KATRIN, respectively.

The Neutrino Mass Experiment KATRIN

The KArlsruhe TRItium Neutrino (KATRIN) experiment is a large-scale experiment with the objective to determine the effective electron antineutrino mass in a model-independent way with an unprecedented sensitivity of 0.2 eV/c2 at 90% C.L. The measurement method is based on the precision B-decay spectroscopy of molecular tritium. The experimental setup consists of a high-luminosity windowless gaseous tritium source, a magnetic electron transport system with differential cryogenic pumping for the tritium retention, and an electrostatic spectrometer section for the energy analysis, followed by a segmented detector system for the counting of transmitted B-electrons. The first KATRIN neutrino mass measurement phase started in March 2019. Here, we will give an overview of the KATRIN experiment and its current status.

Gamma-induced background in the KATRIN main spectrometer

The KATRIN experiment aims to measure the effective electron antineutrino mass $$m_{\overline{\nu }_e}$$mν¯e with a sensitivity of $${0.2}\,{\hbox {eV}/\hbox {c}^2}$$0.2eV/c2 using a gaseous tritium source combined with the MAC-E filter technique. A low background rate is crucial to achieving the proposed sensitivity, and dedicated measurements have been performed to study possible sources of background electrons. In this work, we test the hypothesis that gamma radiation from external radioactive sources significantly increases the rate of background events created in the main spectrometer (MS) and observed in the focal-plane detector. Using detailed simulations of the gamma flux in the experimental hall, combined with a series of experimental tests that artificially increased or decreased the local gamma flux to the MS, we set an upper limit of $${0.006}\,{\hbox {count}/\hbox {s}}$$0.006count/s (90% C.L.) from this mechanism. Our results indicate the effectiveness of the electrostatic and magnetic shielding used to block secondary electrons emitted from the inner surface of the MS.

Тритиевые источники электропитания на основе гетероструктур AlGaAs/GaAs

We report on the development of a radioisotope power source based on the AlхGaAs1-х/GaAs semiconductor converter of β-radiation and tritium as a radiation source. The transducer efficiencies are compared for three types of β-radiation sources: (i) the tritiated titanium disk, (ii) the tritium lamp of green luminescent glow, and (iii) gaseous tritium. When using a converter based on the Al0.35Ga0.65As/GaAs heterostructure in a tritium capsule, the efficiency η = 5.9% is found with the maximum output specific electric power of 0.56 µW/cm2. Due to the prolonged operational life, such autonomous and compact power sources can be utilized in space technology, underwater systems, growth implants, biomedical sensors, and portable mobile equipment of high realibility.

The Sources and Control of Tritium in Molten Salt Reactor

The fuel salt of molten salt reactor is comprised of LiF-BeF2-ThF4-UF4, which can produce more tritium than PWR. Since tritium is an important radioactive nuclide, and it would cause great damage to the reactor, the process to control tritium from fuel salt is a key point in the operation of molten salt reactor. In this article, the source and control of gaseous tritium is mainly discussed.