Written in English
Thesis (M.Sc.), Dept. of Physics, University of Toronto.
|Contributions||Drake, T. E. (supervisor)|
|The Physical Object|
|Number of Pages||76|
Two large area multistep position sensitive (two dimensional) multiwire proportional counters have been developed for experiments involving study of fission dynamics using general purpose scattering chamber facility at IUAC. Both detectors have an active area of 20 × 10 cm 2 and provide position signals in horizontal (X) and vertical (Y) planes, timing signal for time of flight measurements Cited by: measurement of the fission cross section and of the angular distribution of the fragments emitted, a new geometrical configuration was developed and firstly used in the and campaigns to measure the Th(n,f) reaction, demonstrating the suitability of the method described here. Title: Measurement of the angular distribution of fission fragments using a PPAC assembly at CERN n_TOF Author: D. Tarrï¿½o Subject: Nuclear Inst. and Methods in. The detectors and the samples were tilted 45 with respect to the neutron beam direction to cover all the possible values of the emission angle of the fission fragments. The main features of this setup are discussed and results on the fission fragment angular distribution are provided for the Th(n,f) reaction around the fission threshold.
measurement of angular and energy distributions of neutrons and fission fragments. It is known from previous experimental works: • The main source of prompt fission neutrons (PFNs) is accelerated fission fragments. • The angular anisotropy of neutron emission in the center-of-mass system of fission fragment is not established. Fission fragments angular distributions studies counters was developed for measuring angular distributions of fission fragments The main characteristics of the setup are: multiwire proportional counter with U converter deposited on the cathode. The “profile meter” was tested and now is . Calculation of Angular Momentum of Fission Frag-ments. In order to calculate the angular momentum distribu-tion of ﬁssion fragments, a model, ﬁrst proposed by Rasmussen et al.,6 and later extended to the deformed complementary ﬁs-sion fragments by Pfabe and Dietrich,7,8 was followed. The ∗Corresponding author. E-mail: [email protected] In addition, the angular distribution of the fragments produced in the fission of highly excited and deformed nuclei is an important observable to investigate the nuclear fission process. In order to measure the FFAD of neutron-induced reactions, a fission detection setup based on parallel-plate avalanche counters (PPACs) has been developed and.
Measurement Techniques vol Y.V., Lendel, A.I. et al. Determination of angular distributions of fission fragments from isolated masses by semiconductor gamma-spectrometry. Meas T 90–93 (). https://doi Angular Distribution; Fission Fragment; Access options Buy single article. The detectors and the samples were tilted 45° with respect to the neutron beam direction to cover all the possible values of the emission angle of the fission fragments. The main features of this setup are discussed and results on the fission fragment angular distribution are provided for the Th(n,f) reaction around the fission threshold. Fig. 1: Fission fragment angular distribution for 19F + Pt @ MeV is shown (solid square) and lines are the values obtained by W(θ) fitting. Fission cross-sections were obtained using following expression; ruth fis mon mon fiss fission Y Y 2 1 where Ω fiss and Ω mon are solid angle subtended by fission and monitor detector. It has often been stated that fission fragment angular anisotropy, as predicted by equilibrium statistical theory, should disappear with increasing spin of the composite nucleus. However, several recent experimental studies reveal strong anisotropies for fission fragments from high-spin nuclear systems. We discuss this apparent discrepancy and its relationship to the rigid-rotor approximation.