In this paper we present results from measurements of prompt $$\gamma${}$ rays from the thermal neutron induced fission of ${}^{235}$U. Photons were measured in coincidence with fission fragments with cerium-doped LaCl${}_{3}$ and LaBr${}_{3}$ as well as CeBr${}_{3}$ scintillation detectors, which offer an intriguing combination of excellent timing resolution and good resolving power. The spectra measured with all employed detectors are in excellent agreement with respect to their shapes. Characteristic parameters were extracted for a $$\gamma${}$-energy range from 0.1 to 6.0 MeV and the results obtained with several detectors were averaged. From that, the average emission yield of prompt-fission $$\gamma${}$ rays was determined to be ${\overline{$\nu${}}}_{$\gamma${}}=(8.19\ifmmode\pm\else\textpm\fi{}0.11)$ per fission, the average energy per photon to be ${$\epsilon${}}_{$\gamma${}}=(0.85\ifmmode\pm\else\textpm\fi{}0.02)$ MeV, and the total energy to be ${E}_{$\gamma${},\mathrm{tot}}=(6.92\ifmmode\pm\else\textpm\fi{}0.09)$ MeV. The uncertainties are much lower than the 7.5$%$ requested for the modeling of advanced nuclear reactor cores. Estimating the influence of $$\gamma${}$ rays with energies between 6 and 10 MeV on the values determined in this work revealed a negligible deviation of the order of the found uncertainties.

A measurement of the 235U prompt fission neutron spectrum (PFNS) was performed at the Budapest Nuclear Research Reactor at 100 K incident neutron energy. The motivation for this investigation was to verify some literature data measured over the past 20 years that contradict the Los Alamos model, as well as integral data, benchmark (Keff) experiments, and recent spectral data taken at 0.5 MeV incident neutron energy. The measured spectra using three neutron detectors are in excellent agreement with each other. The average spectrum confirms literature data within the error bars in the neutron energy range of 0.7 to 10 MeV. However, the present PFNS shape cannot predict integral experimental data. It seems to be clear now that the disagreement between microscopic and macroscopic data is not connected with a systematic experimental error in the PFNS at low incident neutron energy.