The result of this task is essentially what we get when we run the program, namely the histograms that represent the data. They are showed below.






This plot shows the momentum of the tracks. The y-axis is number of counts and the x-axis is momentum in units GeV/c. We can see that it peaks at approximately 200MeV/c for both offline and HLT data. Both decreases exponentially, and the maximum momentum for any track is around 3GeV/c. Also note that the offline data contributes with more entries than the HTL data, which is the case in all the plots.




This plot shows the transverse momentum of the tracks, with the same units as the previous plot. This plot has the same features as the previous one. Note that the mean of both the offline and HLT data is smaller than the previous one, which makes sense, since we only deal with one component in this case. Also, as predicted, both the total and the transverse momentum shows a shape that is resemblant of a Maxwell distribution.






The next plot show the distribution of the theta angle. This is the polar angle of the scattering process, with scattering-axis, z-axis, parallel to the beam. So it is the transverse angle between the particles momentum and the beam pipe. We see that both plots show peaks at approximately π/2, which says that most particles has momentum that is perpendicular to the beam pipe.

We see that this plot shows the peak discussed in the expectations, and also that the total momentum and the transverse momentum share the same features.






This plot show the distribution of what is called the phi angle, which is the azimuthal angle with the z-axis along the beam pipe. As we can see, this does not show any significant regularity, which makes sense if we ask “why should one azimuthal angle be preferred over the other?”. This was also mentioned in the expectations. We see that it spans an angle of 2π, which is a feature of the azimuthal angle in spherical coordinates.






This plot shows the time projection chamber clusters per track. We see a large difference between the offline and HLT data at zero. Both the plots have no tracks with TPC clusters per track between the values 0 and 30, and no tracks with more that 160.






The last plot shows the charged track multiplicity(CTM) per event. We see that many of the events has no charged tracks for both plots. Note the blue offline bin at zero which is almost hidden by the red line. After the peak at zero, the CTM per event decreases steadily, and goes to zero at around 100.