Hannover 2010 – scientific programme
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MO: Fachverband Molekülphysik
MO 29: Poster: Experimental Techniques
MO 29.6: Poster
Thursday, March 11, 2010, 16:00–18:30, Lichthof
An apparatus for the experimental observation of the angular correlation of two photons detected in coincidence — •Irina Haar1, Rainer Hentges1, Kari Jänkälä2, and Arno Ehresmann1 — 1Institute of Physics University of Kassel, Heinrich-Plett-Straße 40, 34134 Kassel, Germany — 2University of Oulu Department of Physics, 90041 Finland
An apparatus is devised that allows to investigate the angular correlation of two Lyman-α photons emitted coincidentally by dissociation fragments of doubly excited hydrogen molecules. This coincidence technique is advantageous for the investigation of neutral dissociation processes of molecular doubly or multiplies excited states when no ions are formed.
The experimental set up contains a home-built target cell with two position sensitive detectors for the measurement of fluorescence with k→-vectors of 90∘/-90∘ or 0∘/90∘ relative to the E→-vector of the linearly polarized synchrotron light. In order to obtain a large solid angle of the fluorescence radiation two parabolic off-axis mirrors are used, one for each detector branch. The interaction volume, which is defined by the crossing of the synchrotron radiation and the effusive gas jet, is placed in the focal point of both mirrors. The metal needle for the gas jet is adjustable in three dimensions. The mirrors image the emitted photons on the position sensitive detectors. The high spatial and time resolutions of the used detectors based on delay lines provide an angularly detection of the coincident photons. The general layout and the first recorded experimental data will be presented.