Measurement of the photon structure function at low $Q^{2}$ using the ALEPH detector

This thesis describes research analysis carried out on data obtained from the ALEPH detector at LEP during 1993/94. The process gamma gamma -> hadrons, with a single tag in the range of 24-58 mrad, has been observed. This process has also been simulated using Monte Carlo models allowing comparisons to be made between the observed and simulated data. Two Monte Carlo models (HERWIG and PHOJET) were used and the data from these were found to be in agreement with the experimental data. The photon structure function F sub 2 supgamma has been measured in five ranges of Q sup 2 inside the total range of 0.5 and 6.5 GeV sup 2. This was done by reconstructing the Bjorken x sub t sub r sub u sub e distribution from the x sub v sub i sub s data using the Blobel unfolding method. No low x rise is detected within the range of these measurements. These results are found to agree with the predictions of theoretical models in the higher Q sup 2 bins however the agreement is not as good in the lower Q sup 2 bins. These results agree with previous experimental data.