Stuttgart 2012 – wissenschaftliches Programm
Q 42.1: Vortrag
Donnerstag, 15. März 2012, 10:30–10:45, V38.04
Development of an in-situ method for the spectral sensitivity calibration of Raman systems — •Simone Rupp — Institute of Experimental Nuclear Physics, Karlsruhe Institute of Technology
By studying the spectrum of tritium beta decay electrons at its endpoint, the KArlsruhe TRItium Neutrino experiment (KATRIN) will model-independently measure the neutrino mass with an expected sensitivity of 0.2 eV (90% C.L.). To reach this sensitivity, the composition of the continuously injected tritium gas T2, which contains also small fractions of the other hydrogen isotopologues (H2, D2, HD, HT, DT), has to be known at any time with a precision of 0.1%. The determination and monitoring of the isotopologues’ respective fractions is done by the Laser Raman system (LARA) at the Tritium Laboratory Karlsruhe.
For quantitative analysis of the gas composition, the measured spectrum is compared with calculated spectra based on quantum mechanical matrix elements. This procedure requires a precise knowledge of secondary effects influencing the measured spectrum. The Raman scattered light, which is produced during the passage of the laser beam through the sample cell, is collected by an optical system and analyzed by a spectrometer and a CCD. Since this detection system’s sensitivity is wavelength and polarization dependent, a spectral calibration is necessary in order to be able to correctly interprete the resulting spectrum. Currently an in-situ calibration method using LEDs is being developed. In this talk, first ideas for the realization will be presented and discussed.