Neutronography: history and trends of further progress

Abstract

The results of optimisation of active and passive negative feedback (NF) for generation of stable compressed picosecond pulse trains in Nd:glass and Nd:YAG lasers using a modulator driven by fast photomultiplier and a GaAs passive element are presented. Conditions of prolonged pulse trains generation with the duration of trains varied from 0.3 µs to 200 µs depending on parameters of active NF were investigated. Generation of long (1000 ns) pulse trains in passive NF regime was obtained. Pulse compression in active and passive NF regimes (from 8 ps to 1.4 ps and from 35 ps to 13 ps, respectively) was achieved.

The role of demagnetization factor in determining the ‘true’ value of the Curie temperature

“…More exact methods to determine T C include the Mössbauer technique and neutron scattering [6,7]. In the first case, one can observe vanishing hyperfine magnetic nuclear field at the Curie temperature.…”