Hith resolution β-spectroscopy of the isotope 36Cl using magnetic calorimeters

This thesis describes the development of a high resolution magnetic calorimeter for the detection of the β-spectrum of the isotope 36Cl with endpoint energy of 709.6 keV. The temperature rise of a metallic paramagnetic sensor due to an energy deposition is sensed by measuring its magnetization using a sensitive DC-SQUID magnetometer. For a high detection efficiency an 4π gold absorber was used. The heat capacity and the geometry of the absorber is optimally matched by a flat sensor and an optimized meander shaped readout coil. The fabrication of the superconducting structures and the detector setup are described. In addition, the relevant noise sources, the energy resolution and the quantum efficiency are discussed. A measured 36Cl-spectrum with an energy resolution of ΔEFWHM=750 eV is presented and compared with existing experimental and theoretical data. (orig.)