Particle Physics at Low Energies

Course with Participations of Group Members

Offers for Theses in the Group

Characterisation of non-depolarising neutron mirrors

Among else, the PERC facility at the FRM II aims to determine the element V_ud of the CKM quark-mixing matrix from neutron betay decay with unprecedented precision. It will measure the parity-violating beta asymmetry similar to the seminal experiment by Wu and colleagues. This requires prior knowledge of the polarisation of the neutron beam at the 0.1 permille level. A non-depolarising neutron guide contains the cold neutron beam inside the strong magnetic field of the 12m long superconducting magnet system of PERC. The guide consists of a novel layer system of copper and titanium. Within this project, we will perform a measurement campaign at the Institut Laue-Langevin, Grenoble, France, to characterise the (de)polarisation properties of these neutron mirrors using two different techniques: off-specular reflection of a polarised beam and a custom setup using two state of the art polarised He3 spin-filter cells. You will participate in the preparation and execution of the campaign and contribute to the data analysis.

suitable as

• Bachelor’s Thesis Physics

Supervisor: Bastian Märkisch

Design of a Scintillation Detector with Drift Monitoring via a Pulser System

The Proton and Electron Radiation Channel (PERC) facility, currently being set up at the FRM II, aims to measure the beta-asymmetry in neutron decay an order of magnitude more precisely to determine parameters of the Standard Model and to search for new physics beyond it. A system of superconducting coils guides the decay products towards the detector systems. PERC has one primary, downstream detector system and a secondary system located upstream, that will identify events with backscattered electrons from the primary detector. At first, the primary detector will be based on a fast plastic scintillator and photomultiplier tubes, similar to the detectors of previous experiments. Calibrating the detectors is a key factor in achieving the precision aimed at. Radioactive sources with mono-energetic electrons serve for the calibration. A pulser system continuously monitors the detector’s drift with short, controlled light pulses. The pulser system, which includes a Kapustinsky pulser, a silicon photomultiplier and temperature sensors, is being controlled via an Arduino. Within this project, the student will design and assemble the first primary detector for PERC and commission it including the pulser system. The performance of the detector will studied, including simulations based on Geant4.

suitable as

• Master’s Thesis Applied and Engineering Physics

Supervisor: Bastian Märkisch

Electron-magnet-spectrometer for detector characterisation

Precision spectroscopy of electrons from neutron decay allows to determine Standard-Model parameters like the CKM quark-mixing matrix element V_ud and to search for physics beyond the Standard Model like scalar and tensor interactions. At the intense neutron source FRM II we currently take the spectrometer PERC into operation. In order to characterise and optimise the detector systems in the lab, a magnetic spectrometer will serve as a source of (nearly) mono-energetic electrons. Within this project the existing apparatus will be taken into operation and optimised to measure the response of scintillation detectors with a SiPM readout, as well as silicon detector systems.

suitable as

• Master’s Thesis Nuclear, Particle, and Astrophysics

Supervisor: Bastian Märkisch

Optical pulser system for detector calibration

The Proton and Electron Radiation Channel (PERC) facility, currently being set up at the FRM II, aims to measure the beta-asymmetry in neutron decay an order of magnitude more precisely to determine parameters of the Standard Model and to search for new physics beyond it. A system of superconducting coils guides the decay products towards the detector systems. Calibrating the detectors is a key factor in achieving the precision aimed at. Radioactive sources with mono-energetic electrons serve for the calibration. A pulser system continuously monitors the detector’s drift with short, controlled light pulses. The pulser system, which includes a Kapustinsky pulser, a silicon photomultiplier and temperature sensors, is being controlled via an Arduino. Within this project, the pulser system will be put in operation, the communication with the system will be programmed and the system properties of it will be characterized in the laboratory.

suitable as

• Bachelor’s Thesis Physics

Supervisor: Bastian Märkisch

Current and Finished Theses in the Group