Exercise 3 – Belle II experiment

From the measured momentum and energy of two particles $(p_1, E_1)$ and $(p_2, E_2)$ the mass of the mother particle can be calculated as

$mc^2=\sqrt{(E_1+E_2)^2-(p_1+p_2)^2 c^2 )}$

By using a ‘particle combiner’ block, the mass of the particle can be calculated for each combination of particles.

Plot the mass distribution of neutral pion $\pi^0$ which decay to two γ photons:

$\pi^0 \longrightarrow \gamma\gamma$

You will find a peak at 0.135 $\mathrm{GeV}/c^2$ , which is exactly the mass of the pion.