Nukleare Astrophysik

Lehrveranstaltungen mit Beteiligung der Arbeitsgruppe

Ausgeschriebene Angebote für Abschlussarbeiten an der Arbeitsgruppe

Development of a Multi-Channel Plate Time of Flight system for the European Recoil separator for Nuclear Astrophysics (ERNA)

Novae are the result of a thermonuclear runaway (TNR) on the surface of a white dwarf star, resulting in a cataclysmic explosion and the synthesis of new elements (nucleosynthesis) up to calcium. They are also likely the source of the ^6,7Li budget of the universe. The nuclear reactions which occur in the TNR involve proton capture on stable and short-lived radioative nuclei. These reactions all occur at kinetic energies well below the Coulomb barrier, meaning the reation cross sections are very small.. As a result, directly measuring their reaction rates requires creative experimental facilities with high beam intensities and extremely high background suppression.

The European Recoil separator for Nuclear Astrophysics (ERNA) in Castera, Italy, is a unique European facility designed for the direct measurements of astrophysically important thermonuclear reaction rates, satisfying the requirements of high beam intensity and high background suppression. We are now actively dveloping a scientific program at ERNA to measure nova thermonuclear reaction rates, starting with the ³³S + p --> ³⁴Cl + γ reaction, which is important for understanding the isotopic ratios of ^32,33,34S in presolar grains (star dust trapped in meteorites) and gamma-ray astronomy. As part of this development, a new time of fight (TOF) detector system is planned for installation at ERNA to enhance background suppression and discrimination of fusion events.

Development of this TOF system will occur jointly at the ERNA facility itself and locally at TUM, using beams from the 14 MV tandem accelerator of the Maier-Leibnitz laboratory. Succesful development of the TOF system for a masters degree would be naturally followed by a doctoral project of measuring the ³³S(p,γ)³⁴Cl thermonuclear reaction rate at the ERNA facility.

geeignet als

• Masterarbeit Kern-, Teilchen- und Astrophysik

Themensteller(in): Shawn Bishop

Feasibility Study for Measuring Nova Thermonuclear Reaction Rates at the CRYRING, GSI

Novae are the result of a thermonuclear runaway (TNR) on the surface of a white dwarf star, resulting in a cataclysmic explosion and the synthesis of new elements (nucleosynthesis) up to calcium. They are also likely the source of the ^6,7Li budget of the universe. The nuclear reactions which occur in the TNR involve proton capture on stable and short-lived radioative nuclei. These reactions all occur at kinetic energies well below the Coulomb barrier, meaning the reation cross sections are very small.. As a result, directly measuring their reaction rates requires creative experimental facilities with high beam intensities and extremely high background suppression.

Presently at GSI, Darmstadt, the CRYRING ion storage ring is being installed and commisioned. It is an ion-storage ring in which radioactive beams of ions are injected and circulated in a "race track" configuration, at 100 kHz. With this circulation frequency, the beam of radioactive ions impinges on a state of the art supersonic hydrogen gas jet target 10⁵ times per second, thereby increasing the beam's effective luinosity and making possible the chance to measure low energy thermonuclear reaction rates relavent to nucleosynthesis and novae explsions.

This thesis project will be a feasibility study to determine the neccesary requirements for successful  measurement of the ³⁴Cl(p,γ)³⁵Ar thermonuclear reaction rate. The student will utilize the GEANT4 simulation package in a full model of the entire CRYING experimental setup (electromagnetic fields, gas target, detector systems, and residual gas in the beam line). This simulation has been developed by collaborators at GSI. It is therefore an already established tool for the student to use, rather than build from scratch. The student will also spend some weeks on-site at GSI, working with GEANT4 experts to learn the software and implement physics cases within the software to determine the feasibility of measuring this reaction rate; in addition, the time spent at GSI will also offer the student the direct opportunity to see "hands-on" development and installation of the CRYING itself.

Completion of this project would then be a natural doorway into an experimental doctoral thesis to measure, using the CRYING and knowledge learned in this project, the nova ³⁴Cl(p,γ)³⁵Ar thermonuclear reaction rate, utilizing a radioactive ion beam of ³⁴Cl.

geeignet als

• Masterarbeit Kern-, Teilchen- und Astrophysik

Themensteller(in): Shawn Bishop

Abgeschlossene und laufende Abschlussarbeiten an der Arbeitsgruppe