Advisor(s)
Abstract(s)
<p>We report a study of the distributions of the depth of maximum, <inline-formula><mml:math display="inline"><mml:msub><mml:mi>X</mml:mi><mml:mi>max</mml:mi></mml:msub></mml:math></inline-formula>, of extensive air-shower profiles with energies above <inline-formula><mml:math display="inline"><mml:mrow><mml:mn>1</mml:mn><mml:msup><mml:mrow><mml:mn>0</mml:mn></mml:mrow><mml:mrow><mml:mn>17.8</mml:mn></mml:mrow></mml:msup><mml:mtext> </mml:mtext><mml:mtext> </mml:mtext><mml:mi>eV</mml:mi></mml:mrow></mml:math></inline-formula> as observed with the fluorescence telescopes of the Pierre Auger Observatory. The analysis method for selecting a data sample with minimal sampling bias is described in detail as well as the experimental cross-checks and systematic uncertainties. Furthermore, we discuss the detector acceptance and the resolution of the <inline-formula><mml:math display="inline"><mml:msub><mml:mi>X</mml:mi><mml:mi>max</mml:mi></mml:msub></mml:math></inline-formula> measurement and provide parametrizations thereof as a function of energy. The energy dependence of the mean and standard deviation of the <inline-formula><mml:math display="inline"><mml:msub><mml:mi>X</mml:mi><mml:mi>max</mml:mi></mml:msub></mml:math></inline-formula> distributions are compared to air-shower simulations for different nuclear primaries and interpreted in terms of the mean and variance of the logarithmic mass distribution at the top of the atmosphere.</p>