Progress report on measurement and fitting of pulse shapes of moderators at IPNS

We present a progress report on measurements and fitting of pulse shapes for neutrons emerging from one solid and two liquid methane moderators in Intense Pulsed Neutron Source. A time-focused crystal spectrometer arrangement was used with a cooled Ge monochromator. Data analysis of one of the liquid methane moderators has shown the need for some generalization of the Ikeda-Carpenter function that worked well for fitting pulse shapes of polyethylene moderators. We described attempts to model physical insight into the wavelength dependence of function parameters. (author)