Hadronenstruktur und Fundamentale Symmetrien

Prof. Stephan Paul


Our group involved in a number of research projects dealing with high energy particle physics and neutron physics.


James-Franck-Str. 1/I
85748 Garching b. München
+49 89 289 12572
Fax: +49 89 289 12570

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Production and detection of meta-stable hydrogen atoms

 Context: The neutron decay is for many years subject of intense studies, as it reveals detailed information about the structure of the weak interaction. Using the two-body neutron decay into a hydrogen atom and an electron antineutrino n → H + the hyperfine population of the emerging hydrogen atom can be investigated.

Some of the produced hydrogen atoms (~ 10%) are in the meta-stable state 2S.

This special hydrogen atoms from the neutron decay are almost mono-energetic (325.7 eV), because of the nature of the two-body decay. 

In a first step we want to develop techniques to detect these special H(2S) atoms and analyze their properties (energy and hyperfine states).

We have recently constructed and built a time-of-flight setup (Bradbury-Nielsen gate chopper) with a strong proton source, by means of which we can measure the energy of charged particles with a resolution in the eV- region.

H(2S) can also be produced with protons, if they are passing a region with low pressure Cs-vapor. These atoms can be transformed in H-  by interaction with Ar-  vapor.

The 2S state can be detected by quenching the atom with the aid of an electric field to the 1S state. The emitted Lyman-alpha photons can be detected with a special photomultiplier.  The H- atoms can be measured with a magnetic spectrometer  or an electrostatic deflector.

All measurements with charged/neutral particles are done with a multi-channel-plate detector.


The working program of this master thesis is divided in:


-        Set up the Cs- and Ar- vapor system in the existing proton beam line

-        Set up of the quenching system with the photomultiplier

-        Design of the electrostatic deflector system (CAD and calculations with a beam optic program like TRANSPORT)

-        Measurements with the new setup.


Physics goals:

-        Determination of the charge transfer cross section of argon for H(2S) atoms for energies lower than 500 eV.

-        Development of a electrostatic deflector spectrometer

-        Optimization of a quenching system for H(2S) atoms


geeignet als
  • Masterarbeit Kern-, Teilchen- und Astrophysik
Themensteller(in): Stephan Paul

Abgeschlossene und laufende Abschlussarbeiten an der Arbeitsgruppe

Untersuchung zu Pion-Photon-Reaktionen mit neutralen Pionen im Endzustand an COMPASS (CERN)
Abschlussarbeit im Masterstudiengang Physik (Kern-, Teilchen- und Astrophysik)
Themensteller(in): Jan Michael Friedrich

Kern-, Teilchen-, Astrophysik

Ziel der Forschung ist das Verständnis unserer Welt auf subatomarem Niveau, von den Atomkernen im Zentrum der Atome bis hin zu den elementarsten Bausteinen unserer Welt.