Fermilab is an American particle physics laboratory, named after the Italian physicist Enrico Fermi - Leaving Cert Physics - Question a - 2020

Mesons are subatomic particles made up of one quark and one antiquark. They are part of the hadron family and mediators of strong interactions, existing in various types such as pions and kaons.

The three types of neutrinos in order of increasing mass are:

1. Electron neutrino
2. Muon neutrino
3. Tau neutrino

No tunnel is required for transporting neutrinos underground because they interact very weakly with matter. They can pass through large amounts of material, including the Earth, without significant interaction.

To calculate the time taken (t) for the neutrino to travel 1300 km at a speed of 0.99c, use the formula:

$t = \frac{d}{v}$

where:

• d = 1300 km = $1.3 \times 10^6$ m
• v = 0.99c = 0.99 \times (3.00 \times 10^8 m/s)

Calculating:

$t = \frac{1.3 \times 10^6 m}{0.99 \times 3.00 \times 10^8 m/s} \approx 4.4 \times 10^{-3} \text{ seconds}$

Using the total energy (E) in the system and the mass-energy equivalence from Einstein's equation, we know:

$E = mc^2$

In this case, total energy after collision is 42 GeV. Thus, converting GeV to joules and solving for mass:

$E = 6.72 \times 10^{-3} \text{ } (J)$

Therefore:

$m = \frac{E}{c^2} = \frac{6.72 \times 10^-3}{(3 \times 10^8)^2} \approx 7.48 \times 10^{-26} \text{ kg}$

Nuclear fission is the process of splitting a large nucleus into smaller nuclei, accompanied by the emission of energy and neutrons. This reaction is typically initiated by the absorption of a neutron.

Fermi's nuclear reactor was considered self-sustaining because it achieved a chain reaction, whereby one fission event causes further fission events, maintaining the reaction without external prompts.

Graphite was used in Fermi's reactor as a neutron moderator, slowing down neutrons to increase the rate of fission, thus improving reactor efficiency.

Nuclear fission is generally considered a non-spontaneous process, as it requires an initial input, such as a neutron, to initiate the reaction, rather than occurring spontaneously without external influence.