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Christopher Richards edited sectionConclusion_Th.tex
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\section{Methods}
\subsection{Resolution of Scintillator}
The resolution of the scintillator was assessed by varying the voltage of the PMT and adjusting the amplifier gain setting. The 31keV peak found from Cs137 was chosen as it’s shift was observable over a wider range of parameter combinations. The full-width half-maximum (FWHM) was recorded for each peak shift, allowing the resolution to be calculated using :
FWHM(keV)/31keV
\subsubsection{Resolution with Gain}
Variation of the coarse gain setting was used. The gain was varied from 1 to 200, with a constant voltage. Table ### shows the combination of parameters used for this section.
\subsubsection{Resolution with Voltage}
The voltage was set as low as possible to observe distinguishable peaks for the Cs137 spectrum, with a gain of 60. The voltage was increased by 100V until the PMT’s limit of 1200V. Table ### shows the combination of paramters used for this section.
\subsection{Gamma Ray spectra of Various sources}
The spectrum of available sources was recorded using the highest gain setting with a mid-range voltage (700-900V). Each sample was recorded for 120 seconds using 1024 channels. This provided a set of peaks over a range of energies that could be used for attenuation measurements.
\subsection{Energy dependence on attenuation}
Measurement of the attenuation coefficient for a series of materials of differing density was performed over a range of gamma ray energies. The materials analysed were lead, polyethylene (PE), aluminium and steel. Lead and PE discs of differing thicknesses were used, whilst sheets of steel and aluminium were added to record to attenuation of a variety of thicknesses. This process was repeated for each source. Table ### shows the corresponding energies and sources that were used in this study. The mass attenuation coefficient was also recorded using density values provided by NIST.
Each sample was recorded for 60 seconds using the parameters specific for the source, where the resultant parameters are outlined in the results section.
