Identification of Different Reaction Channels of High-energy Neutrons in Liquid Scintillators By the Pulse-shape Discrimination Method

A study of the n-gamma discrimination with NE213 and BC501A liquid scintillators, carried out with 40 and 56 MeV neutron beams, reflects different reaction channels involved in the detection process of high energy neutrons. Up to seven different reaction channels were identified in the pulse shape discrimination spectrum measured by a digital charge comparison method. The analysis of the energy spectra of the secondary particles allowed the cross sections for different reaction channels to be estimated as well. This is shown for the important C-12(n, d) reaction and the non-negligible contribution of the C-12(n, t) reaction to the total efficiency of the NE 213 liquid scintillator for neutrons

Computer-aided engineering for sheet metal forming: definition of a springback quality function

Computer-aided engineering methods are extensively applied to sheet metal forming integrated design. The adoption of a new class of materials, the advanced high strength steels, has increased the occurrence of springback, and consequently the request for tools oriented to springback reduction and optimization. This paper presents an approximated formulation to compute the springback field after stamping through the finite element analysis of the process. This can be found assuming that the residual field of nodal forces after stamping produces a springback shape referable to a linear combination of n modes of vibration of the nominal shape of the component. The aim of this formulation is not that of substituting the finite element analysis of the springback but rather to make use of the coefficients of the linear combination, so to define a global quality function for springback. In this way, Robust Design methods or other current optimization procedures to improve the stamping process as for structural defects (such wrinkling, necking and flatness) can be applied also for the reduction of springback. The meaning of these coefficients will be shown through three test cases and the consistency of the formulation will be discussed according to the number of modes of vibration included in the computation. © 2012 Springer-Verlag London Limited