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PD Dr. rer. nat. habil. Jochen Greiner

Phone
30000-3847
Room
E-Mail
gu56sil@mytum.de
Links
Homepage
Page in TUMonline
Group
Max-Planck-Institue for Extraterrestrial Physics (MPE)
Job Title
PD at the Physics Department

Courses and Dates

Offered Bachelor’s or Master’s Theses Topics

Alarm-Software fuer Gammastrahlungs-Transienten

The recent detection of gravitational waves (GW) with the advanced LIGO/Virgo instruments in conjunction with a short gamma-ray burst (GRB) has surprised gamma-ray astronomers because of the substantially different properties of the GRB  signal as compared to canonical GRBs. This motivates an "open-mind" search for untriggered transient events in the data stream of the gamma-ray burst monitor (GBM) on the Fermi satellite. With two previous Bachelor theses we have developed a physical background model, paving the way for automated searches, and subsequent source and background fitting.
 
This thesis shall be devoted to establishing a Python program for identifying long-term (> few minutes up to a year) transients in Fermi/GBM data, localizing them on the sky, and deriving basic properties (spectrum, light curve). One pot\ential application is to determine the spectral properties of the predicted seasonal variation of the background due to axions. The project includes elements from computational and observational high-energy astrophysics, and will allow for obtaining extensive knowledge on the broad class of high-energy transients. 
 
Some background in astrophysics is advantegeous, but affinity with Python programming is a must. 
 
Contact: Jochen Greiner, jcg@mpe.mpg.de, MPE Room 1.3.13, Tel. 30000-3847

suitable as
  • Master’s Thesis Nuclear, Particle, and Astrophysics
Supervisor: Jochen Greiner
GEANT-4 Simulation eines Compton Teleskopes

The COMPTEL instrument measured the 0.7-30 MeV emission of the sky for nearly 10 years in the 90ies. This energy range includes interesting nuclear lines from elements which are produced in the winds of massive stars, or in supernova explosions. In addition, the instrument is a perfect polarimeter - and X-/gamma-ray polarimetry is still considered the holy grail of astrophysics. Even now, 20 years later, its data are unique, and no future mission is on the horizon for the next 20 years. However, our computational tools have drastically improved, allowing analysis types which were completely impractical at the time COMPTEL was operated.

This thesis shall take our mass model and perform GEANT4 simulations for two cases: (i) line emission from stellar gamma-ray sources, and (ii) polarized continuums emission. Based on the simulated data, new cuts in the multi-dimentional data space should be found which separate background photons from source photons. Finally, these cuts should be applied to a test data set of COMPTEL in order to evaluate the improvement in the performance.

Technically, this thesis involves learning about (i) data analysis of Compton gamma-ray detectors, (ii) understanding detector effects, (iii) simulating an observation with different levels of statistics, and (iv) characterizing a multi-dimentional parameter space using e.g. principal component analysis.

Some background in astrophysics is advantegeous, and experience with GEANT4 would be perfect. Some Python knowledge is required. Joy in data analysis is required.

Contact: Jochen Greiner, jcg@mpe.mpg.de, MPE Room 1.3.13, Tel. 30000-3847

suitable as
  • Bachelor’s Thesis Physics
Supervisor: Jochen Greiner
Test einer Anger Kamera fuer Gamma-Spektroskopie

The improvements of Silicon photo-multipliers (SiPM) over the last years qualify them as promising replacements for classical photo-multiplier tubes (PMT). This is particularly interesting for cases where the high voltages and large dimensions of PMTs are difficult to afford, such as for space applications. For the simplest version of gamma-ray detectors, a scintillator crystal read out by SiPMs, the size of the scintillator determines the sensitivity, and thus should stay large. This suggests an Anger camera principle as the most efficient way for a gamma-ray detector in space: a mosaic of sparsely distributed single-cell SiPMs instead of the coverage of the full scintillator area.

This Master thesis shall test and optimize a 5x5 cm^2 sized CeBr3 scintillator read out with a mosaic of SiPMs. Measurements of the spatial and spectral resolution as well as efficiency (noise) and power consumption are foreseen, and form the basic parameters for the trade-off study. The set-up has two potential applications: (i) in the ComPol Cubesat mission pursued within the Origins Cluster of Excellence, and (ii) the POLAR-2 gamma-ray burst polarisation mission developed within the SFB "Neutrinos and Dark Matter".

Interest in electronics and ASIC readout is required, and some background in astrophysics is advantegeous. The lab-work will be done at MPP Freimann, shared with Prof. S. Mertens group.
 
Contact: Jochen Greiner, jcg@mpe.mpg.de, MPE Room 1.3.13, Tel. 30000-3847

suitable as
  • Bachelor’s Thesis Physics
  • Master’s Thesis Nuclear, Particle, and Astrophysics
Supervisor: Jochen Greiner
Verbesserung der Positionsbestimmung von GRBs

Gamma-ray bursts (GRBs) are flashes of gamma-rays resulting from the death of massive stars or the merger of neutron stars. The latter also produce gravitational waves. The presently most prolific GRB detector is the "Gamma-Ray Burst Monitor" (GBM) on the Fermi satellite, containing 12 NaI scintillation detectors. The position is derived by comparing the relative count rates in the differently oriented scintillator planes.

This thesis shall use existing flight data of the brightest gamma-ray source on the sky (the Crab nebula) and improve the spatial resolution of the response matrix of selected detectors. The result shall be tested by localizing selected GRBs with GBM, and comparison against known positions of these GRBs from other satellites (e.g. Swift).

Technically, this thesis involves learning of (i) learning the basics of GRBs, (ii) data analysis of non-imaging gamma-ray detectors, (iii) understanding and correcting detector effects, (iv) fitting light curves with different count statistics, and (v) analyzing and combining large amounts of individual constraints into a coherent picture.

Some background in astrophysics is advantegeous. Python knowledge is required, and good programming skills. Joy in data analysis is required.

    Contact: Jochen Greiner, jcg@mpe.mpg.de, MPE Room 1.3.13, Tel. 30000-3847

suitable as
  • Bachelor’s Thesis Physics
Supervisor: Jochen Greiner
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