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Stored and Cooled Ions Division
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Master and bachelor theses

Master / Ph.D. thesis:
Cryogenic Microcalorimeter for Mass sensitive detection of fast neutral reaction products

Preliminary design of the MOCCA chamber

Gas-phase molecular-ion reactions play a key role in many environments, such as astrophysical media (e.g. interstellar clouds), tokamak plasmas, and industrial plasmas. Due to a lack of reliable theoretical calculations, these reactions must be explored in laboratory. Reactions of polyatomic ions often result in multiple products. While the charged product can be identified by a variety of mass-spectrometric techniques, the neutrals products are difficult to treat. To overcome this limitation we are constructing a unique detector based on cryogenic micro-calorimeter operating at ~10 miliKelvin.

The MOleCular CAmera (MOCCA) will measure kinetic energies of reaction fragments from ions in a fast beam of known velocity. From that the fragment masses can be determined easily even for neutrals. Moreover, the detector will be segmented in 4096 pixels providing multi-hit capability and position resolution. The relative fragment positions will tell the reactant/product excitation state. All together these capabilities make the MOCCA a worldwide unique tool for investigating reactions of molecular ions with neutral products, such as dissociative recombination, electron-capture dissociation, collision-induced dissociation, photo-fragmentation, etc.

The detector-chip is currently being manufactured at the Kirchhoff-Institute, Heidelberg, while the specialized housing and cooling facility is partly in the design phase and partly being purchased. We expect to first operate the detector in 2017 using ion beams from the 300~keV ion platform of MPIK and dissociated by a crossed laser beam. Quantum-dynamic studies using ultra-fast lasers are foreseen as well. Later, the detector will be integrated in the Cryogenic Storage Ring (CSR) at MPIK and continue the investigations on photon- and laser-induced reactions with internally cold molecular ions.

The Ph.D./ Master candidate will follow the construction of the MOCCA-detector-setup and perform first measurements. The work includes the design-finalizing of the vacuum chamber, the data-acquisition system development, detector performance simulation, etc. The candidate will learn several interesting experimental techniques and technologies, ranging from handling of extremely high vacuum (<10-13 mbar), through extremely low temperatures (<0.01 K), to analysis of multidimensional datasets. For Master candidates, there are enough sub-projects available, contact us for details.



Dr. Oldrich Novotný ()
Apl. Prof. Dr. Andreas Wolf ()
Max-Planck-Institut für Kernphysik (MPIK), Heidelberg

Some relevant publications:

Novotný, O. et al., J. Appl. Phys. 118, 104503 (2015) external Link