| 1 | We also produce neutrons. | |
| 2 | Each proton (or neutron) has about two thousand times the mass of an electron. | |
| 3 | So we get at the number of neutrons indirectly because we know the proton number here. | |
| 4 | So we're looking only for the neutrons at energy E from this spectrum. | |
| 5 | Quarks are the constituents of protons and neutrons, as well as more exotic things. |