The history of anti-matter begins in 1928 when a young English physicist named Paul Dirac predicted an anti-particle for the electron - Leaving Cert Physics - Question 10 - 2010

Pair production is a phenomenon where energy is converted into matter, specifically a particle and its anti-particle, due to interaction with a high-energy photon (often a gamma ray). This process conserves both energy and momentum.

To find the kinetic energy of one particle produced from pair production, we use the energy-frequency relation:

$E = h f$

where $h = 6.626 \times 10^{-34} \text{ J s}$ is the Planck constant and $f = 3.6 \times 10^{18} \text{ Hz}$. Thus,

$E = 6.626 \times 10^{-34} \text{ J s} \times 3.6 \times 10^{18} \text{ Hz} = 2.376 \times 10^{-15} \text{ J}$

Now, using the relation between energy and mass,

$E = mc^2$

we substitute the rest mass ($m = 9.1 \times 10^{-31} \text{ kg}$ and $c = 3.0 \times 10^8 \text{ m/s}$) to find the total energy:

$E = (9.1 \times 10^{-31} \text{ kg}) \times (3.0 \times 10^8 \text{ m/s})^2 = 8.19 \times 10^{-14} \text{ J}$

The kinetic energy of one particle (after accounting for rest mass energy) is given by

$E_k = E - E_{rest} = 2.376 \times 10^{-15} \text{ J} - 8.19 \times 10^{-14} \text{ J} = 3.69 \times 10^{-14} \text{ J}$.

The meson family consisting of up and down quarks and their anti-particles results in the following combinations:

• Combination 1: $u$ (up) + $d$ (down) [\text{Charge: } +1/3 + -1/3 = 0 ]
• Combination 2: $u$ (up) + $\bar{d}$ (anti-down) [\text{Charge: } +1/3 + +1/3 = +2/3 ]
• Combination 3: $\bar{u}$ (anti-up) + $d$ (down) [\text{Charge: } -1/3 + -1/3 = -2/3 ]
• Combination 4: $\bar{u}$ (anti-up) + $\bar{d}$ (anti-down) [\text{Charge: } -1/3 + +1/3 = 0 ]

The name 'quark' was first introduced by the famous Irish writer James Joyce.