The KArlsruhe TRItium Neutrino (KATRIN) experiment will measure the absolute mass scale of neutrinos with a sensitivity of mν = 200 meV c2 by high-precision spectroscopy close to the tritium β-decay ...endpoint at 18.6 keV. Its Windowless Gaseous Tritium Source (WGTS) is a β-decay source of high intensity (1011 s−1) and stability, where high-purity molecular tritium at 30 K is circulated in a closed loop with a yearly throughput of 10 kg. To limit systematic effects the column density of the source has to be stabilized at the 10−3 level. This requires extensive sensor instrumentation and dedicated control and monitoring systems for parameters such as the beam tube temperature, injection pressure, gas composition and so on. In this paper, we give an overview of these systems including a dedicated laser-Raman system as well as several β-decay activity monitors. We also report on the results of the WGTS demonstrator and other large-scale test experiments giving proof-of-principle that all parameters relevant to the systematics can be controlled and monitored on the 10−3 level or better. As a result of these works, the WGTS systematics can be controlled within stringent margins, enabling the KATRIN experiment to explore the neutrino mass scale with the design sensitivity.
•We report about experimental results of a new tritium activity monitoring system using the BIXS method.•The system is compact and easy to implement. It has a small dead volume of about 28cm3 and can ...be used in a flow-through mode.•Gold coated surfaces are used to improve significantly count rate stability of the system and to reduce stored inventory.
To develop a convenient tool for in-line tritium gas monitoring, the TRitium Activity Chamber Experiment (TRACE) was built and commissioned at the Tritium Laboratory Karlsruhe (TLK). The detection system is based on beta-induced X-ray spectrometry (BIXS), which observes the bremsstrahlung X-rays generated by tritium decay electrons in a gold layer. The setup features a measuring chamber with a gold-coated beryllium window and a silicon drift detector. Such a detection system can be used for accountancy and process control in tritium processing facilities like the Karlsruhe Tritium Neutrino Experiment (KATRIN). First characterization measurements with tritium were performed. The system demonstrates a linear response between tritium partial pressure and the integral count rate in a pressure range of 1Pa up to 60Pa. Within 100s measurement time the lower detection limit for tritium is (143.63±5.06)·104Bq. The system stability of TRACE is limited by a linear decrease of integral count rate of 0.041%/h. This decrease is most probably due to exchange interactions between tritium and the stainless steel walls. By reducing the interaction surface with stainless steel, the decrease of the integral count rate was reduced to 0.008%/h. Based on the first results shown in this paper it can be concluded that TRACE is a promising complement to existing tritium monitoring tools.
In this work, we present the first spectroscopic measurements of conversion electrons originating from the decay of metastable gaseous 83mKr with the Karlsruhe Tritium Neutrino (KATRIN) experiment. ...The obtained results represent one of the major commissioning milestones for the subsequent direct neutrino mass measurement with KATRIN. The successful campaign demonstrates the functionalities of the KATRIN beamline. Precise measurement of the narrow K-32, L3-32, and N2,3-32 conversion electron lines allowed to verify the eV-scale energy resolution of the KATRIN main spectrometer necessary for competitive measurement of the absolute neutrino mass scale.
The gas circulation loop LOOPINO has been set up and commissioned at Tritium Laboratory Karlsruhe (TLK) to perform Raman measurements of circulating tritium mixtures under conditions similar to the ...inner loop system of the neutrino-mass experiment KATRIN, which is currently under construction. A custom-made interface is used to connect the tritium containing measurement cell, located inside a glove box, with the Raman setup standing on the outside. A tritium sample (purity > 95 %, 20 kPa total pressure) was circulated in LOOPINO for more than three weeks with a total throughput of 770 g of tritium. Compositional changes in the sample and the formation of tritiated and deuterated methanes CT
4-n
X
n
(X=H,D; n=0,1) were observed. Both effects are caused by hydrogen isotope exchange reactions and gas-wall interactions, due to tritium β decay. A precision of 0.1 % was achieved for the monitoring of the T
2
Q
1
-branch, which fulfils the requirements for the KATRIN experiment and demonstrates the feasibility of high-precision Raman measurements with tritium inside a glove box.
► Development of a new BIXS-system for activity monitoring of gaseous tritium sources. ► High sensitivity by use of an low-noise easy to operate silicon drift detector. ► Gas-species independent ...tritium monitoring.
For monitoring and control of gaseous tritium sources in fuel circulation systems of fusion reactors beta induced X-ray spectrometry (BIXS) seems to be an applicable method. The characteristics of a BIXS monitoring setup built at TLK were examined. A low-noise silicon drift detector (SDD) was used together with two thin beryllium windows evaporated with gold films of 100nm for efficient X-ray production. The measured X-ray intensity was proportional to the tritium partial pressure and the average detection efficiency was evaluated as 32.6×10−8cps/Bq. A tritium memory effect was revealed. From the results it was concluded that such a monitoring system would be a useful complement for tritium analytics devices if well designed in terms of memory effect suppression.
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