Investigation of detector response functions of internal bremsstrahlung spectrums with SVD (singular value decomposition) method

In this study, we tried to obtain the spectrum of Internal Bremsstrahlung photons which were released simultaneously with beta particles and neutrino from the 90Sr-90Y source in secular equilibrium. The experimental data of the photon spectrum were acquired using 2x2" NaI (Tl) detector. Detector parameters of the detector were determined using standard calibration sources. A detector response function was generated for a single-energy gamma photon using detector parameters and Monte Carlo method and its compatibility with experimental values was observed. In the same way, a detector response function (matrix) was created in certain energy ranges. The Singular Value Decomposition (SVD) mathematical method was used to unfold the detector response function effects from the raw spectrum obtained after extraction of natural background from experimental data. Using this method and the generated detector response matrix together, the experimental data were unfolded from the effects of the detector response function and the internal bremsstrahlung spectrum of the 90Sr-90Y source was obtained. Experimental data were compared with KUB theory and other studies, and there was a much better agreement between experimental and theoretical findings than other experimental data.