Development of a non-depolarizing neutron guide for PERC

The cold neutron beam station PERC (Proton Electron Radiation Channel)[1] is developed for measurements of angular correlation coefficients in beta-decay of free polarized neutrons with a precision of 10^{-4}. Inside PERC the neutron beam is confined laterally by the guide equipped with a supermirror. The neutron guide within PERC (where the ''active decay volume'' lies) has to be non-depolarizing at the same precision level of 10^{-4}. The depolarization may take place during reflection of neutrons from the guide walls with supermirror magnetic coatings placed in a strong magnetic field. In this thesis the feasibility of using supermirrors based on diamagnetic Cu and paramagnetic Ti instead of the traditionally used non-ferromagnetic Ni(Mo) or Ni(V) alloys and Ti is investigated. Development and production of the Cu/Ti supermirror coating are performed at Heidelberg University and described in this thesis. The first depolarization test of the Cu/Ti multilayer covering, m=1.2, was done at the reflectometer of polarized neutrons at a reactor of the Institute Laue-Langevin, France. The reflectometer was based on the Opaque Test Bench [2], a tool for investigation neutron depolarization with high accuracy. The second depolarization test of the Cu/Ti multilayer samples, m=1.55 and m=1.7, and Ni(Mo)/Ti sample, m=1.5, was performed at the research reactor Munich II, Germany. The special reflectometer of polarized neutrons was built and optimized for the measurement of small neutron depolarization. The accuracy of this measurement was limited to 5*10^{-3} at the region of our interest. We suffer from the neutron depolarization caused by the specificity of used polarizer and analyzer in geometry of the experiment. No depolarization effect was observed in both experiments at the level of precision of the measurements

Design of the Magnet System of the Neutron Decay Facility PERC

The PERC (Proton and Electron Radiation Channel) facility is currently under construction at the research reactor FRM II, Garching. It will serve as an intense and clean source of electrons and protons from neutron beta decay for precision studies. It aims to contribute to the determination of the Cabibbo-Kobayashi-Maskawa quark-mixing element $V_{ud}$ from neutron decay data and to search for new physics via new effective couplings. PERC's central component is a 12m long superconducting magnet system. It hosts an 8m long decay region in a uniform field. An additional high-field region selects the phase space of electrons and protons which can reach the detectors and largely improves systematic uncertainties. We discuss the design of the magnet system and the resulting properties of the magnetic field.Comment: Proceedings of the International Workshop on Particle Physics at Neutron Sources PPNS 2018, Grenoble, France, May 24-26, 201

Design of the magnet system of the neutron decay facility PERC

The PERC (Proton and Electron Radiation Channel) facility is currently under construction at the research reactor FRM II, Garching. It will serve as an intense and clean source of electrons and protons from neutron beta decay for precision studies. It aims to contribute to the determination of the Cabibbo-Kobayashi-Maskawa quark-mixing element Vud from neutron decay data and to search for new physics via new effective couplings. PERC's central component is a 12 m long superconducting magnet system. It hosts an 8 m long decay region in a uniform field. An additional high-field region selects the phase space of electrons and protons which can reach the detectors and largely improves systematic uncertainties. We discuss the design of the magnet system and the resulting properties of the magnetic field