22.4: Monday 11-12 ------------------ Exercise 2.2: - there is an inaccuracy in the model solution of c). *lambda_I was missing. The depth of first interaction (*lambda_I = 50 g/cm2) should be added to the values of calculated X_{max}! - (a)-(c) the following points were addressed: * Heitler model together with the superposition principle results in Nmax-values, which are roughly 10 x bigger than the values of more sophisticated EAS-models (as given in the lecture slides 3.17, 3.20) * Heitler model together with the superposition principle results in Xmax-values, which are larger (the showers penetrate more deeper) than the values of Xmax as expressed in the lecture slides (3.28 - 3.30., 3.37 and 3.46). * Heitler model together with the superposition principle DOES predict a logarithmic dependence of Xmax vs. E and a logarithmic dependence on mass number A ! You may compare these predictions of the model with the lecture slides (3.28 - 3.30., 3.37 and 3.46). The model is fairly ok. Heitler-model is actually a model of electromagnetic showers (gamma's and electrons). The EAS initiated by protons or other nuclei are hadronic in nature (the EAS contains baryons and mesons = kaons, pions etc.) and the model is not applicable to proton or nucleus initiated EAS in that sense.. - (d) to calculate this task, it was required to acquire the density of air at 10 km from external sources. The task demonstrates the subtle 'competition' of pion decay vs. pion interaction in the development of air showers. Exercise 3.1: - the model plot is in log-log scale. To use a linear-scale is just fine. (Different ways of making a plot point out different details). A continuation question was given: Why does the muon energy vs. depth -curve bend? Exercise 3.2: - here it was left to the student to study about the structure and dimensions of our Milky Way. We discussed also why *lambda are given in units of g/cm2. Please remember that there any no dumb questions! Only dumb answers.