Weakly Interacting Massive Particles (WIMPs) have been proposed to constitute the cold dark matter, which is the dominant matter fraction in our galaxy as well as in the universe, at the same time being well motivated by supersymmetric extensions of the standard model of particle physics. Current experiments aiming at the detection of galactic WIMPs base on elastic scattering of WIMPs from atomic nuclei in suitably prepared detectors. The CRESST experiment established the simultaneous measurement of phonons and scintillation light induced by nuclear recoils in CaWO$_4$ crystals. While the different ratios of light yield and energy deposition (so-called Quenching Factors, QF) from electron and nuclear recoils provide a powerful tool for radioactive background discrimination, the individual determination of the Quenching Factors of oxygen, calcium and tungsten in CaWO$_4$ have not been measured so far. This knowledge is essential for the interpretation of the CRESST data in separating the potential WIMP signal from background induced by ambient neutrons. At the tandem accelerator in Garching, Germany, a neutron scattering facility for the calibration of the detector response to nuclear recoils has been designed, set up and commissioned. A collimated mono-energetic neutron beam with an energy of 11 MeV was produced by an inverse (p,n) reaction. These neutrons are scattered in a central detector whose response to nuclear recoils is under investigation. The scattered neutrons are detected by mobile arrays of 40 neutron detectors in total. The nuclear recoil energy is fixed by fixing the scattering angle, allowing to determine QF as ratio between recoil energy and signal height in the central scintillation detector. After the operational performance of this facility has been verified by the determination of the Quenching Factors of hydrogen in a NE213 and sodium in a NaI(Tl) scintillation detector at room temperature, for the first time the different Quenching Factors of the elements in the bulk of a CaWO$_4$ crystal were determined separately at room temperature. For the calibration of the Quenching Factors at low temperatures, a dilution refrigerator is integrated in the scattering facility and put into operation. The objective of this work is the description of the experimental setup of the neutron scattering facility, the determination of Quenching Factors in NE213, NaI(Tl) and CaWO$_4$ scintillators and their relation to characteristics of ion stopping. This dissertation starts with an introduction into the search for Cold Dark Matter Particles, detection methods and the CRESST experiment in Chapter 1. Chapter 2 motivates the need for a detector calibration by neutron scattering and discusses the basic concept of such a scattering experiment. Starting with the planning of a scattering setup and ending with the interpretation of scattering data, a detailed knowledge about the fundamental nuclear reaction processes and their cross sections is mandatory. Chapter 3 gives a summary over the nuclear reaction that are involved, kinematic transformations that are indispensable for scattering calculations are summarized in Appendix A. The nucleus, recoiling from the neutron deflection, generally leaves its original site together with tightly bound electrons of the inner atomic shells; the so-formed ion collides with atoms of the detector material and generates heat and electronic excitations during its stopping process. The variety of stopping processes together with a calculation of ion ranges and the fraction of ionization and phonons, generated during the slowing down of the ion, are described in Chapter 4. A part of the electronic excitation energy produced within the detector may be transferred to luminescence centres giving rise to a measurable scintillation signal. Scintillation processes for the luminophors used in this work together with a description of quenching processes are described in Chapter 5. After having built the theoretical fundament, the experimental setup is described in detail in Chapter 6: starting with an appropriate choice of a monoenergetic neutron source, the detection of neutrons is described, the geometry of the setup, followed by an explanation of the whole data acquisition assembly. A special section is devoted to the scintillation light detection from CaWO$_4$ due to the complexity of operations involved. With the facility being commissioned, Quenching Factors in NE 213, NaI(Tl) and CaWO$_4$ are measured. These results are presented and discussed in Chapter 7. An outlook with emphasis on the installation of a cryostat for measurements at low temperatures rounds off this work.
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Weakly Interacting Massive Particles (WIMPs) have been proposed to constitute the cold dark matter, which is the dominant matter fraction in our galaxy as well as in the universe, at the same time being well motivated by supersymmetric extensions of the standard model of particle physics. Current experiments aiming at the detection of galactic WIMPs base on elastic scattering of WIMPs from atomic nuclei in suitably prepared detectors. The CRESST experiment established the simultaneous measuremen...
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