Photon mass attenuation coefficients are indispensable input parameters for use in several disciplines. They are of value for medical diagnostics, radiation therapy, material science, etc. Currently, photon mass attenuation coefficients derived from model calculations are widely used. This project directly measured the photon mass attenuation coefficients of water and a number of water based solutions. These measurements were made using a High Purity Germanium (HPGe) detector allowing for increased resolution beyond traditional techniques. Four sources were used (\Ba, \Eu, \Cs, \Am) producing multiple photons of interest over the range of 40 keV to 1.4 MeV, allowed for simultaneous collection of data and a refining of uncertainties beyond past techniques. Direct measurements using a new liquid technique supported the validity of Bragg's additive law, allowing for the mass attenuation coefficient of a constituent element to be calculated from a set of independent measurements. This technique allows materials not easily directly measured to be determined without an overburdening increase in uncertainty. The same direct measurements showed a deviation from the currently relied upon National Institute of Standards and Technology (NIST) database - XCOM. Investigations of the deviation and surrounding references showed XCOM being at most accurate to 5 \% relative uncertainty.

The content of this thesis is the validation of the method of dynamic testing of solar photovoltaic cells. Testing methods for determining the parameters of the photovoltaic cell replacement scheme has been verified through testing a set of crystalline silicon photovoltaic cells. To accelerate the diffusion capacity measurement and to improve reproducibility of the measurement we propose new method of determining the time constant for diffusion capacitance using a combination of two short pulses. For this method of measurement new scheme for dynamic tester timing has been proposed and implemented.