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The KATRIN experiment aims to measure the effective electron antineutrino mass \\[m_{\\overline{\\nu }_e}\\] with a sensitivity of \\[{0.2}\\,{\\hbox {eV}/\\hbox {c}^2}\\] 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}}\\] (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.

The KATRIN experiment aims to determine the effective electron neutrino mass with a sensitivity of \\[{0.2}{\\hbox { eV/c}^{2}}\\] (%90 CL) by precision measurement of the shape of the tritium \\[\\upbeta \\]-spectrum in the endpoint region. The energy analysis of the decay electrons is achieved by a MAC-E filter spectrometer. A common background source in this setup is the decay of short-lived isotopes, such as \\[{}^{\\text {219}}\\text {Rn}\\] and \\[{}^{\\text {220}}\\text {Rn}\\], in the spectrometer volume. Active and passive countermeasures have been implemented and tested at the KATRIN main spectrometer. One of these is the magnetic pulse method, which employs the existing air coil system to reduce the magnetic guiding field in the spectrometer on a short timescale in order to remove low- and high-energy stored electrons. Here we describe the working principle of this method and present results from commissioning measurements at the main spectrometer. Simulations with the particle-tracking software Kassiopeia were carried out to gain a detailed understanding of the electron storage conditions and removal processes.

The KArlsruhe TRItium Neutrino experiment (KATRIN) aims to measure the absolute neutrino mass scale with an unprecedented sensitivity of 0.2 eV/c2 (90% C.L.), using beta decay electrons from tritium decay. The kinetic energy of the decay electrons is measured using an electrostatic integrating main spectrometer (MS) with magnetic adiabatic collimation and requires a certain magnetic field profile. For the control of the magnetic field in the MS area two networks of mobile magnetic field sensor units are developed and commissioned. The radial system is operated close to the outer surface of the MS whereas the vertical one is mounted along vertical planes left and right of the MS. The sensor setup can take several thousands magnetic field samples at a fine meshed grid, thus allowing to study the magnetic field inside the MS and the influence of magnetic materials in the vicinity of the main spectrometer.

The KATRIN experiment is a next-generation direct neutrino mass experiment with a sensitivity of 0.2 eV (90% C.L.) to the effective mass of the electron neutrino. It measures the tritium \\(\\beta\\)-decay spectrum close to its endpoint with a spectrometer based on the MAC-E filter technique. The \\(\\beta\\)-decay electrons are guided by a magnetic field that operates in the mT range in the central spectrometer volume; it is fine-tuned by a large-volume air coil system surrounding the spectrometer vessel. The purpose of the system is to provide optimal transmission properties for signal electrons and to achieve efficient magnetic shielding against background. In this paper we describe the technical design of the air coil system, including its mechanical and electrical properties. We outline the importance of its versatile operation modes in background investigation and suppression techniques. We compare magnetic field measurements in the inner spectrometer volume during system commissioning with corresponding simulations, which allows to verify the system's functionality in fine-tuning the magnetic field configuration. This is of major importance for a successful neutrino mass measurement at KATRIN.

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 beta-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 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.

The goal of the KArlsruhe TRItrium Neutrino (KATRIN) experiment is the determination of the effective electron antineutrino mass with a sensitivity of 0.2 eV/c\\(^2\\) at 90% C.L. This goal can only be achieved with a very low background level in the order of 0.01 counts per second. A possible background source is \\(\\alpha\\)-decays on the inner surface of the KATRIN Main Spectrometer. Two \\(\\alpha\\)-sources, \\(^{223}\\)Ra and \\(^{228}\\)Th, were installed at the KATRIN Main Spectrometer with the purpose of temporarily increasing the background in order to study \\(\\alpha\\)-decay induced background processes. In this paper, we present a possible background generation mechanism and measurements performed with these two radioactive sources. Our results show a clear correlation between \\(\\alpha\\)-activity on the inner spectrometer surface and background from the volume of the spectrometer. Two key characteristics of the Main Spectrometer background -the dependency on the inner electrode offset potential, and the radial distribution - could be reproduced with this artificially induced background. These findings indicate a high contribution of \\(\\alpha\\)-decay induced events to the residual KATRIN background.

The KArlsruhe TRItium Neutrino experiment (KATRIN) aims to measure the electron neutrino mass with an unprecedented sensitivity of 0.2 eV/c2, using b decay electrons from tritium decay. For the control of magnetic field in the main spectrometer area of the KATRIN experiment a mobile magnetic sensor unit is constructed and tested at the KATRIN main spectrometer site. The unit moves on inner rails of the support structures of the low field shaping coils which are arranged along the the main spectrometer. The unit propagates on a caterpillar drive and contains an electro motor, battery pack, board electronics, 2 triaxial flux gate sensors and 2 inclination senors. During operation all relevant data are stored on board and transmitted to the master station after the docking station is reached.

To determine the magnetic field distribution in the KATRIN main-spectrometer with magnetic field sensors that are placed outside the main-spectrometer vessel one can utilize the absence of magnetic rotation in main-spectrometer volume. There a scalar magnetic potential V(~x) can be defined that fulfills the Laplace equation. Large numbers of magnetic field values on an outer surface of the main-spectrometer can be sampled by moving and fixed magnetic field sensors. These surface samples are used as boundary values in the relaxation of the Laplace equation for V(~x) and the magnetic field components in the volume. In a simulation involving the KATRIN reference solenoid chain, a global magnetic field and an external perturbing solenoid it is shown that with this method the original field can be reconstructed within 2 %.

This article discusses the possibility of using a liquid catalyst in selected vegetable fuels. The fuels selected for study are rapeseed oil methyl ester and hemp oil methyl ester. The aim of the research presented in this paper is to evaluate the operating and environmental performance of an engine fueled with selected fuels with a catalytic additive. The tests were carried out on a dynamometer bench using a Fiat 1.3 JTD common rail engine. During the tests, parameters such as engine torque and power, specific fuel consumption, and the emission of nitrogen oxides, hydrocarbons, carbon dioxide, and soot were measured. The tests were carried out on fuels with and without a catalytic converter. The results show that the use of a catalytic additive reduces nitrogen oxides and hydrocarbon emissions for all fuels tested.

Objectives: As surprisingly little is known about the developing brain studied in vivo in youth with Down syndrome (DS), the current review summarizes the small DS pediatric structural neuroimaging literature and begins to contextualize existing research within a developmental framework. Methods: A systematic review of the literature was completed, effect sizes from published studies were reviewed, and results are presented with respect to the DS cognitive behavioral phenotype and typical brain development. Results: The majority of DS structural neuroimaging studies describe gross differences in brain morphometry and do not use advanced neuroimaging methods to provide nuanced descriptions of the brain. There is evidence for smaller total brain volume (TBV), total gray matter (GM) and white matter, cortical lobar, hippocampal, and cerebellar volumes. When reductions in TBV are accounted for, specific reductions are noted in subregions of the frontal lobe, temporal lobe, cerebellum, and hippocampus. A review of cortical lobar effect sizes reveals mostly large effect sizes from early childhood through adolescence. However, deviance is smaller in adolescence. Despite these smaller effects, frontal GM continues to be largely deviant in adolescence. An examination of age-frontal GM relations using effect sizes from published studies and data from Lee et al. (2016) reveals that while there is a strong inverse relationship between age and frontal GM volume in controls across childhood and adolescence, this is not observed in DS. Conclusions: Further developmentally focused research, ideally using longitudinal neuroimaging, is needed to elucidate the nature of the DS neuroanatomic phenotype during childhood and adolescence. (JINS, 2018, 24, 966–976)