Exercise 7: Trig functions
(15 minutes)
The quantity theta, or the angle that the beam makes with the z-axis, is calculated by:
\[
\theta = \arctan\left(\frac{p_{T}}{p_{z}}\right)
\]
The units are radians. Revise your script to include a histogram of theta.
I’ll make your life a little easier
The math function you want is ROOT.TMath.ATan2(y,x)
, which computes
the arctangent of y/x. It’s better to use this function than
ROOT.TMath.ATan(y/x)
, because the ATan2
function correctly handles
the case when x=0.

Figure 58: https://xkcd.com/447/ by Randall Munroe