The KArlsruhe TRItium Neutrino experiment (KATRIN) aims to measure the mass of electron neutrinos from beta-decay of tritium with an unprecedented sensitivity of 0.2 eV/c^2 improving present limits by one order of magnitude. The decay electrons will originate from a 10 m long windowless, gaseous tritium source. Super-conducting magnets guide the electrons through differential and cryogenic pumping sections to the electro-static tandem spectrometer (MAC-E-filter), where the kinetic energy will be measured. The experiment is presently being built at the Forschungszentrum Karlsruhe by an international collaboration of more than 120 scientists. The largest component, the 1240 m^3 main spectrometer, was delivered end of 2006 and first commissioning tests have been performed. This presentation describes the goals and technological challenges of the experiment and reports on the progress in commissioning first major components. The start of first measurements is expected in 2012.
The Karlsruhe Tritium Neutrino (KATRIN) experiment will provide a measurement of the effective electron-neutrino mass, $m(ν_e)$, based on a precision measurement of the tritium beta decay spectrum near its endpoint. The effective mass is an average of the neutrino mass eigenvalues $m_i$ weighted by the flavor-mass mixing parameters $U_{ei}$ according to the relation $m^2(ν_e)= \sum_{i=1}^3 |U_{ei} |^2 m_i^2$. The KATRIN apparatus uses a windowless gaseous tritium source (WGTS) and a spectrometer based on the MAC-E filter concept to measure the beta energy spectrum. The KATRIN program is design…
The Karlsruhe Tritium Neutrino Experiment (KATRIN) measures the effective electron anti-neutrino mass with an unprecedented design sensitivity of 0.2 eV (90 % C.L.). In this experiment, the energy spectrum of beta electrons near the tritium decay endpoint is analyzed with a highly accurate spectrometer. To reach the KATRIN sensitivity target, the retarding voltage of this spectrometer must be stable to the ppm level and well known on various time scales ($μs$ up to months), for values around -18.6 kV. A custom-designed high-voltage regulation system mitigates the impact of interference sources…
The KArlsruhe TRItium Neutrino (KATRIN) experiment is designed to measure tritium $β$-decay spectrum with enough precision to be sensitive to neutrino mass down to 0.2eV at 90$\%$ Confidence Level. After an initial first tritium run in the summer of 2018, KATRIN is taking tritium data in 2019 that should lead to a first neutrino mass result. The $β$ spectral shape of the tritium decay is also sensitive to four countershaded Lorentz Violating (LV), oscillation-free operators within the Standard-Model Extension that may be quite large. The status and outlook of KATRIN to produce physics results,…
The KATRIN experiment aims at measuring the electron neutrino mass with a sensitivity of 0.2 eV$/c^2$ after five years of data taking. Recently a new upper limit for the neutrino mass of 0.8 eV$/c^2$ (90% CL) was obtained. To reach the design sensitivity, a reduction of the background rate by one order of magnitude is required. The shifted analysing plane (SAP) configuration exploits a specific shaping of the electric and magnetic fields in the KATRIN main spectrometer to reduce the spectrometer background by a factor of two. We discuss the general idea of the SAP configuration and describe th…
The KATRIN (Karlsruhe Tritium Neutrino) experiment investigates the energetic endpoint of the tritium beta-decay spectrum to determine the effective mass of the electron anti-neutrino. The collaboration has reported a first mass measurement result at this TAUP-2019 conference. The TRISTAN project aims at detecting a keV-sterile neutrino signature by measuring the entire tritium beta-decay spectrum with an upgraded KATRIN system. One of the greatest challenges is to handle the high signal rates generated by the strong activity of the KATRIN tritium source while maintaining a good energy resolut…
The KATRIN (Karlsruhe Tritium Neutrino) experiment investigates the energetic endpoint of the tritium $β$-decay spectrum to determine the effective mass of the electron anti-neutrino with a precision of $200\,\mathrm{meV}$ ($90\,\%$ C.L.) after an effective data taking time of three years. The TRISTAN (tritium $β$-decay to search for sterile neutrinos) group aims to detect a sterile neutrino signature by measuring the entire tritium $β$-decay spectrum with an upgraded KATRIN system. One of the greatest challenges is to handle the high signal rates generated by the strong activity of the KATRIN…
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 $β$-electrons produced inside the windowless gaseous tr…
Sterile neutrinos are a minimal extension of the Standard Model of Particle Physics. If their mass is in the kilo-electron-volt regime, they are viable dark matter candidates. One way to search for sterile neutrinos in a laboratory-based experiment is via tritium-beta decay, where the new neutrino mass eigenstate would manifest itself as a kink-like distortion of the $β$-decay spectrum. The objective of the TRISTAN project is to extend the KATRIN setup with a new multi-pixel silicon drift detector system to search for a keV-scale sterile neutrino signal. In this paper we describe the requireme…
We investigate the sensitivity of the Karlsruhe Tritium Neutrino Experiment (KATRIN) to keV-scale sterile neutrinos, which are promising dark matter candidates. Since the active-sterile mixing would lead to a second component in the tritium $β$-spectrum with a weak relative intensity of order $\sin^2θ\lesssim 1\times10^{-6}$, additional experimental strategies are required to extract this small signature and to eliminate systematics. A possible strategy is to run the experiment in an alternative time-of-flight (TOF) mode, yielding differential TOF spectra in contrast to the integrating standar…
The KArlsruhe TRItium Neutrino experiment (KATRIN) aims to measure the effective electron anti-neutrino mass with an unprecedented sensitivity of 0.2 eV/c$^2$, using beta-electrons from tritium decay. Super-conducting magnets will guide the electrons through a vacuum beam-line from the windowless gaseous tritium source through differential and cryogenic pumping sections to a high resolution spectrometer. At the same time tritium gas has to be prevented from entering the spectrometer. Therefore, the pumping sections have to reduce the tritium flow by at least 14 orders of magnitude. This paper …
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 $α$-decays on the inner surface of the KATRIN Main Spectrometer. Two $α$-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 $α$-decay induced background processes. In this paper, w…
A precision 32 keV angular-selective photoelectron source for calibration measurements at the KATRIN experiment
University of Münster（明斯特大学）；Karlsruhe Institute of Technology (KIT)（卡尔斯鲁厄理工学院）；University of Washington（华盛顿大学）；Max-Planck-Institut für Kernphysik（马克斯·普朗克核物理研究所）；Istituto Nazionale di Fisica Nucleare (INFN)-Sezione di Milano-Bicocca（意大利国家核物理学会米兰比可卡分部）
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 $β$-decay spectrum close to its endpoint with a spectrometer based on the MAC-E filter technique. The $β$-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 achiev…
KATRIN Sensitivity to keV Sterile Neutrinos with the TRISTAN Detector Upgrade
University of North Carolina, Chapel Hill（北卡罗来纳大学教堂山分校）；Triangle Universities Nuclear Laboratory（三角大学核实验室）；Karlsruhe Institute of Technology (KIT)（卡尔斯鲁厄理工学院）；University of Münster（明斯特大学）；Istituto Nazionale di Fisica Nucleare (INFN) – Sezione di Milano-Bicocca（意大利国家核物理研究所米兰-比科卡分部）
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…
The KArlsruhe TRItium Neutrino experiment (KATRIN) aims to measure the effective electron anti-neutrino mass with an unprecedented sensitivity of $0.2\,\mathrm{eV}/\mathrm{c}^2$, using $β$-electrons from tritium decay. The electrons are guided magnetically by a system of superconducting magnets through a vacuum beamline from the windowless gaseous tritium source through differential and cryogenic pumping sections to a high resolution spectrometer and a segmented silicon pin detector. At the same time tritium gas has to be prevented from entering the spectrometer. Therefore, the pumping section…
The KATRIN experiment is designed for a direct and model-independent determination of the effective electron anti-neutrino mass via a high-precision measurement of the tritium $β$-decay endpoint region with a sensitivity on $m_ν$ of 0.2$\,$eV/c$^2$ (90% CL). For this purpose, the $β$-electrons from a high-luminosity windowless gaseous tritium source traversing an electrostatic retarding spectrometer are counted to obtain an integral spectrum around the endpoint energy of 18.6$\,$keV. A dominant systematic effect of the response of the experimental setup is the energy loss of $β$-electrons from…
We report on the data set, data handling, and detailed analysis techniques of the first neutrino-mass measurement by the Karlsruhe Tritium Neutrino (KATRIN) experiment, which probes the absolute neutrino-mass scale via the $β$-decay kinematics of molecular tritium. The source is highly pure, cryogenic T$_2$ gas. The $β$ electrons are guided along magnetic field lines toward a high-resolution, integrating spectrometer for energy analysis. A silicon detector counts $β$ electrons above the energy threshold of the spectrometer, so that a scan of the thresholds produces a precise measurement of the…
The neutrino mass experiment KATRIN uses conversion electrons from the 32.2 keV transition of the nuclear isomer $^{\mathrm{83m}}$Kr for calibration. Comparing the measured energies to the appropriate literature values allows for an independent evaluation of the energy scale, but the uncertainties in some of the literature values obtained by gamma spectroscopy are a limiting factor. Building upon the already excellent linearity of KATRIN's energy scale, this paper proposes a novel method for determining the $^{\mathrm{83m}}$Kr transition energies via high-precision electron spectroscopy. Notab…
A pulsed, mono-energetic and angular-selective UV photo-electron source for the commissioning of the KATRIN experiment
KATRIN实验的目标是以200 meV/c^2（90% C. L.）的灵敏度确定中微子质量尺度。通过精确测量氚$β$ -光谱在端点区域的形状。衰变电子的能量分析是通过MAC-E滤波谱仪实现的。为了确定KATRIN主谱仪的透射特性，研制了一种单能角选择电子源。在准备主光谱仪的第二次调试阶段时，在KATRIN监测光谱仪上进行了测量阶段，其中设备在MAC-E过滤器设置中运行以进行测试。这些测量的结果进行了比较，使用粒子跟踪软件“Kassiopeia”，这是在KATRIN合作开发的模拟在最近几年。
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 th…
Stochastic Heating by ECR as a Novel Means of Background Reduction in the KATRIN Spectrometers
KATRIN实验的主要目标是探测绝对中微子质量标度，灵敏度为200 meV（90% C. L.）。通过精确的氚β衰变光谱学为了达到这个目的，在氚β衰变终点区域需要10 ^（-2）cps量级的低本底。用静电减速谱仪进行的测量表明，在谱仪的体积中由核衰变产生的电子被长时间储存，从而作为超过该极限的本底的主要来源。在本文中，我们提出了一种新的主动本底降低方法的基础上随机加热的存储电子的众所周知的过程中的电子回旋共振（ECR）。在KATRIN预光谱仪的测试测量中，ECR技术的原理证明是成功的，从而大大降低了背景速率。此外，我们已经进行了广泛的蒙特卡罗模拟，以揭示潜在的ECR技术，以消除所有被困的电子在主光谱仪的测量时间可以忽略不计的损失。这将使KATRIN实验充分发挥其物理潜力。
The \textit{KArlsruhe TRItium Neutrino} (KATRIN) experiment aims to measure the neutrino mass with a sensitivity of \SI{0.2}{\electronvolt} (\SI{90}{\percent} CL). This will be achieved by a precision measurement of the endpoint region of the $\upbeta$-electron spectrum of tritium decay. The $\upbeta$-electrons are produced in the \textit{Windowless Gaseous Tritium Source} (WGTS) and guided magnetically through the beamline. In order to accurately extract the neutrino mass the source activity is required to be stable and known to a high precision. The WGTS therefore undergoes constant extensiv…
We report on the neutrino mass measurement result from the first four-week science run of the Karlsruhe Tritium Neutrino experiment KATRIN in spring 2019. Beta-decay electrons from a high-purity gaseous molecular tritium source are energy analyzed by a high-resolution MAC-E filter. A fit of the integrated electron spectrum over a narrow interval around the kinematic endpoint at 18.57 keV gives an effective neutrino mass square value of $(-1.0^{+0.9}_{-1.1})$ eV$^2$. From this we derive an upper limit of 1.1 eV (90$\%$ confidence level) on the absolute mass scale of neutrinos. This value coinci…
In this work, we present the first spectroscopic measurements of conversion electrons originating from the decay of metastable gaseous $^\mathrm{83m}$Kr with the Karlsruhe Tritium Neutrino (KATRIN) experiment. The results obtained in this calibration measurement represent a major commissioning milestone for the upcoming direct neutrino mass measurement with KATRIN. The successful campaign demonstrates the functionalities of the full KATRIN beamline. The KATRIN main spectrometer's excellent energy resolution of ~ 1 eV made it possible to determine the narrow K-32 and L$_3$-32 conversion electro…
The KArlsruhe TRItium Neutrino (KATRIN) experiment, which aims to make a direct and model-independent determination of the absolute neutrino mass scale, is a complex experiment with many components. More than 15 years ago, we published a technical design report (TDR) [https://publikationen.bibliothek.kit.edu/270060419] to describe the hardware design and requirements to achieve our sensitivity goal of 0.2 eV at 90% C.L. on the neutrino mass. Since then there has been considerable progress, culminating in the publication of first neutrino mass results with the entire beamline operating [arXiv:1…
Deconvolution of the energy loss function of the KATRIN experiment
KATRIN实验的目标是以0.2 eV/c^2的灵敏度（在90% C. L.）直接和独立于模型地测定中微子质量。通过测量氚β衰变谱的终点区域。该实验的主要组成部分是一个无窗口的气态氚源（WGTS），差分和低温泵浦部分和一个串联的前和主光谱仪，应用磁绝热准直与静电延迟电位的概念来分析β衰变电子的能量，并引导电子通过过滤器到一个分段的硅PIN探测器。这种实验的一个重要的系统不确定性是由于β衰变电子的能量损失的弹性和非弹性散射的氚分子内的源体积，改变测量光谱的形状。为了校正这些影响，需要对相应的能量损失函数进行独立测量。在这项工作中，我们描述了一种反卷积方法提取的能量损失函数的实验在不同的列密度的WGTS使用单能电子源的响应函数的测量。
The Karlsruhe Tritium Neutrino (KATRIN) experiment is a large-scale effort to probe the absolute neutrino mass scale with a sensitivity of 0.2 eV (90% confidence level), via a precise measurement of the endpoint spectrum of tritium beta decay. This work documents several KATRIN commissioning milestones: the complete assembly of the experimental beamline, the successful transmission of electrons from three sources through the beamline to the primary detector, and tests of ion transport and retention. In the First Light commissioning campaign of Autumn 2016, photoelectrons were generated at the …
The KATRIN experiment will determine the effective electron anti-neutrino mass with a sensitivity of 200 meV/c$^2$ at 90% CL. The energy analysis of tritium $β$-decay electrons will be performed by a tandem setup of electrostatic retarding spectrometers which have to be operated at very low background levels of $<10^{-2}$ counts per second. This benchmark rate can be exceeded by background processes resulting from the emanation of single $^{219,220}$Rn atoms from the inner spectrometer surface and an array of non-evaporable getter strips used as main vacuum pump. Here we report on a the impact…
