Improve or remove transmission calculations

[pkienzle]

The transmission calculations from neutron scattering do not match measured transmissions for the same materials. There are a variety of reasons for this, such as phonon scattering, that require more information about the sample and its environment in order to compute correctly. We should consider removing the calculation entirely, or alternatively, improving the calculation so it can be useful.

1. Mildner, D.F.R., Lamaze, G.P., 1998. Neutron Transmission of Single-Crystal Sapphire. J Appl Crystallogr 31, 835–840. https://doi.org/10.1107/S0021889898005846

2. May, R.P., Ibel, K., Haas, J., 1982. The forward scattering of cold neutrons by mixtures of light and heavy water. J Appl Crystallogr 15, 15–19. https://doi.org/10.1107/S0021889882011285

3. Trkov, A., Mattes, M., 2004. On the Thermal Scattering Law Data for Reactor Lattice Calculations 8.

4. Mattes, M., Keinert, J., 2005. Thermal Neutron Scattering Data for the Moderator Materials H2O, D2O and ZrHx in ENDF-6 Format and as ACE Library for MCNP(X) Codes 70.