For use in radiation protection measurements, a neutron spectrometer must have a wide energy range, good sensitivity, medium resolution, and ease of taking and reducing data. No single spectrometer meets all of these requirements. Several experiments aimed at improving and characterizing the detector response to gamma rays and neutrons were conducted. A light pipe (25 mm) was needed between the scintillator cell and the photomultiplier tube to achieve the best resolution. The light output of the scintillator as a function of gamma-ray energy was measured. Three experiments were conducted to determine the light output as a function of neutron energy. Monte Carlo calculations were made to evaluate the effects of multiple neutron scattering and edge effects in the detector. The electronic systems associated with the detector were improved with a transistorized circuit providing the bias voltage for the photomultiplier tube dynodes. This circuit was needed to obtain pulse-height linearity over the wide range of signal sizes. A special live-time clock was built to compensate for the large amount of dead time generated by the pulse-shape discrimination circuit we chose to use. 64 refs., 58 figs., 9 tabs.

This memo discusses the induced polarization field that occurs in the presence of Raman processes, and the propagation equations that result from this field. First the paper summarizes the relationship between the macroscopic polarization field and the microscopic dipole-moment expectation value. It summarizes expressions for the induced dipole moment that result from the adiabatic elimination of non-resonant molecular transitions, to produce an effective two-photon (Raman) Hamiltonian. Then it shows that the polarization field has a similar mode expansion to the electric field. Using this result the equations for pulse propagation of the electric field are described. These equations involve a generalized gain matrix and mode velocity, as well as a refractive index, each of which depends upon position and time. Finally the paper summarizes these results and exhibits succinctly the pulse propagation equations in the plane-wave slowly-varying envelope approximation. The equations presented here must be supplemented with excitation equations (or by steady-state results) for the molecules. The material presented here is a portion of a more extensive treatment of propagation to be presented separately.

As part of a comprehensive examination of equations describing pulsed laser propagation, this memo presents the coupled partial differential equations that describe the propagation of radiation pulses through a vapor of randomly placed molecules that respond by Raman excitation.