de | en

Apl. Prof. Dr. rer. nat. habil. Christoph Pascal Hugenschmidt

Photo von Apl. Prof. Dr. rer. nat. Christoph Pascal Hugenschmidt.
Phone
+49 89 289-14609
Room
E-Mail
hugen@mytum.de
Links
Homepage
Page in TUMonline
Groups
Neutron Scattering
Neutron Scattering
Job Title
Adjunct Professor at the Physics Department
Additional Info
Professor Christoph Hugenschmidt Arbeitsgruppe Physik mit Positronen FRM II - Technische Universität München Lichtenbergstraße 1 D-85748 Garching phone +49 (0)89 289 14609 Christoph.Hugenschmidt@frm2.tum.de https://mlz-garching.de/positrons

Courses and Dates

Title and Module Assignment
ArtSWSLecturer(s)Dates
Physics with positrons 1
eLearning course
Assigned to modules:
VO 2 Hugenschmidt, C. Thu, 08:15–10:00, PH 2271
Seminar on Experimental Methods Using Positrons and Complementary Techniques
Assigned to modules:
PS 2 Hugenschmidt, C. Thu, 10:00–11:30, PH 2224
FOPRA Experiment 60: Positron-Lifetime Measurements in Solids (AEP, KM, KTA)
current information
Assigned to modules:
PR 1 Burwitz, V.
Responsible/Coordination: Hugenschmidt, C.
FOPRA Experiment 86: Measurement of the Fermi Energy by the Angular Correlation of Gamma-Radiation from Annihilation of Electron-Positron Pairs (AEP, KM, KTA)
current information
Assigned to modules:
PR 1 Mathes, L.
Responsible/Coordination: Hugenschmidt, C.
Revision Course to Seminar on Experimental Methods Using Positrons and Complementary Techniques
Assigned to modules:
RE 2
Responsible/Coordination: Hugenschmidt, C.

Offered Bachelor’s or Master’s Theses Topics

Berechnung der Elektron-Positron-Impulsverteilung an Gitterfehlern (ABINIT)

The characterization of lattice defects with respect to their chemical environment is of outmost interest in condensed matter physics and materials science. In coincidence Doppler-broadening spectroscopy (CDBS), both annihilation quanta are detected simultaneously with two high-purity germanium detectors. The resulting background suppression enables the detection of large momenta of core electrons (large Doppler-shifts) in the outer wings of the 511 keV annihilation line. Therefore, CDBS is applied to identify the elements at the annihilation site and hence enables the detection of, e.g., foreign atom-vacancy complexes or precipitates in alloys. Within this thesis CDBS spectra resulting from positron annihilation in point defects will be calculated by using the open-source code ABINIT. This program is based on density functional theory (DFT) and allows the computation of electron and positron densities as well as wave functions in the solid. The calculated  positron lifetimes and positron-electron momentum distributions are compared with experimental results.

The project is carried out within the TUM research group Physics with Positrons.

suitable as
  • Master’s Thesis Condensed Matter Physics
Supervisor: Christoph Pascal Hugenschmidt
Bestimmung der atomaren Leerstellenkonzentration in abgeschrecktem Wolfram durch Doppler-Verbreiterungsspektroskopie der Positronenannihilationslinie
Doppler-broadening spectroscopy (DBS) of the positron annihilation line with a mono-energetic positron beam is a highly sensitive method to characterize lattice defects within the first few microns of a sample. The creation and behaviour of such defects in tungsten is of outmost interest in nuclear fusion research where tungsten is used as inner wall material of the plasma vessel withstanding the high particle flux and heat loads. A material close to its melting point contains a non-negligible thermal vacancy concentration which can be ’frozen in’ by cooling down a sample very fast from high temperature (quenching). The resulting vacancy concentration, however, is not homogeneously distributed as the mobility of vacancies depends heavily on temperature. The goal of this work is to verify experimentally the vacancy distribution calculated theoretically. Since the probing depth ( ≈ 1.5 µm) of DBS is smaller than the depth beyond which the defect concentration is expected to level out (a few 10 µm), multiple DBS measurements are required with intermittent removal of a surface layer (1 µm to 10 µm). The sample preparation and the quenching procedure will be performed at the labs of the workgroup Ion Beam Analysis and Modification at the MPI for Plasma Physics. The project is carried out within the TUM research group Physics with Positrons.
suitable as
  • Bachelor’s Thesis Physics
Supervisor: Christoph Pascal Hugenschmidt
Bestimmung der Positroniumsbildung an Polymeroberflächen mithilfe eines Positronenstrahls
Ziel der Bachelorarbeit ist es, die Bildung von Positronium über die 3-gamma-Annihilation an verschiedenen Polymeroberflächen zu beobachten. Hierzu verwenden wir einen monoenergetischen Positronenstrahl, der durch das Anlegen einer (Hoch-)Spannung auf die Probe beschleunigt wird. Die 3-gamma Annihilation lässt sich routinemäßig mit den vorhandenen Ge-Detektoren messen. Auf diese Weise lässt sich tiefenaufgelöst die Positroniumbildungsrate bestimmen. Das Projekt wird in der TUM Forschungsgruppe Physik mit Positronen durchgeführt.
suitable as
  • Bachelor’s Thesis Physics
Supervisor: Christoph Pascal Hugenschmidt
Simulation der Positronendiffusion bei angelegten elektrischen Feldern zur Bestimmung der Leestellenkonzentration in Festkörpern (LIMPID)
Positronen können je nach Implantationstiefe im Festkörper zurück an die Oberfläche diffundieren, bevor sie annihilieren. Das resultierende Gammaspektrum – insbesondere die Form der 511 keV Annihilationslinie – ändert sich mit dem Anteil der Positronen die an der Oberfläche annihilieren. Eine Simulation der tiefenaufgelösten Diffusion erlaubt es uns, die Leerstellenkonzentration in der Probe aus bei unterschiedlichen Implantationstiefen gemessenen Daten zu bestimmen. Hauptziel der Masterarbeit ist es, den von uns entwickelten Algorithmus zur numerischen Lösung der Diffusionsgleichung in Python zu erweitern, um zusätzliche Effekte, wie variable Defektverteilungen oder elektrische Felder im Inneren der Probe zu berücksichtigen. Das Projekt wird in der TUM Forschungsgruppe Physik mit Positronen durchgeführt.
suitable as
  • Master’s Thesis Condensed Matter Physics
Supervisor: Christoph Pascal Hugenschmidt

Publications

Formation of vacancies and metallic-like domains in photochromic rare-earth oxyhydride thin films studied by in-situ illumination positron annihilation spectroscopy
Ziying Wu (author), Tom de Krom (author), Giorgio Colombi (author), Diana Chaykina (author), Gijs van Hattem (author), Henk Schut (author), Marcel Dickmann (author), Werner Egger (author), Christoph Hugenschmidt (author), Ekkes Brück (author), Bernard Dam (author), Stephan W. H. Eijt (author)
2022-06-21
journal article
Physical Review Materials
DOI: 10.1103/PhysRevMaterials.6.065201
Total-reflection high-energy positron diffractometer at NEPOMUC — Instrumentation, simulation, and first measurements
Matthias Dodenhöft (author), Sebastian Vohburger (author), Christoph Hugenschmidt (author)
2021-11-01
journal article
Review of Scientific Instruments
DOI: 10.1063/5.0062412
Momentum density spectroscopy of Pd: Comparison of 2D-ACAR and Compton scattering using a 1D-to-2D reconstruction method
Josef Ketels (author), David Billington (author), Stephen B. Dugdale (author), Michael Leitner (author), Christoph P. Hugenschmidt (author)
2021-08-30
journal article
Physical Review B
DOI: 10.1103/PhysRevB.104.075160
Injection of positrons into a dense electron cloud in a magnetic dipole trap
M. Singer (author), M. R. Stoneking (author), E. V. Stenson (author), S. Nißl (author), A. Deller (author), A. Card (author), J. Horn-Stanja (author), T. Sunn Pedersen (author), H. Saitoh (author), C. Hugenschmidt (author)
2021-06
journal article
Physics of Plasmas
DOI: 10.1063/5.0050881
Absolute fraction of emitted Ps determined by geant4-supported analysis of gamma spectra
B. Rienäcker (author), T. Gigl (author), G. Nebbia (author), F. Pino (author), C. Hugenschmidt (author)
2020-12-18
journal article
Physical Review A
DOI: 10.1103/PhysRevA.102.062212
Absolute fraction of emitted Ps determined by GEANT4 supported analysis of gamma spectra
2020-10-05
other
ARXIV: arXiv:2010.01854v1
Annealing behaviors of vacancy-type defects in AlN deposited by radio-frequency sputtering and metalorganic vapor phase epitaxy studied using monoenergetic positron beams
Akira Uedono (author), Kanako Shojiki (author), Kenjiro Uesugi (author), Shigefusa F. Chichibu (author), Shoji Ishibashi (author), Marcel Dickmann (author), Werner Egger (author), Christoph Hugenschmidt (author), Hideto Miyake (author)
2020-08-28
journal article
Journal of Applied Physics
DOI: 10.1063/5.0015225
Annealing behavior of open spaces in AlON films studied by monoenergetic positron beams
2018
journal article
Applied Physics Letters
DOI: 10.1063/1.5027257
Carrier Trapping by Vacancy-Type Defects in Mg-Implanted GaN Studied Using Monoenergetic Positron Beams
2018
journal article
physica status solidi (b)
URL: http://dx.doi.org/10.1002/pssb.201700521
DOI: 10.1002/pssb.201700521
Impact and Applications: Positron Beam Experiments at NEPOMUC
2018
journal article
Nuclear Physics News
DOI: 10.1080/10619127.2018.1463022

further publications (total of 132).

See ORCID profile of Christoph Pascal Hugenschmidt as well.

Top of page