Physics of Gamma Radiation

This course explores gamma radiation, its properties, interactions with matter, and methods for calculating energy absorption and penetration depth.

Module 1: Properties of Gamma Radiation

Gamma radiation consists of high-energy photons, emitted from the nucleus of an atom during radioactive decay. It is a form of electromagnetic radiation with very short wavelengths and high frequencies.

Formula:
Energy of Gamma Photon (E):
E = h * f
where
E = energy of gamma photon (J)
h = Planck’s constant (6.626 × 10^-34 J·s)
f = frequency of the gamma photon (Hz)

Example Calculation:
Given a gamma ray frequency of 3 × 10²⁰ Hz, calculate the energy of the photon.
Solution:
E = h * f = (6.626 × 10^-34 J·s) * (3 × 10²⁰ Hz) ≈ 1.99 × 10^-13 J

Module 2: Attenuation of Gamma Radiation

Gamma radiation attenuates as it passes through matter, reducing its intensity due to absorption and scattering.

Formula:
Attenuation of Intensity (I):
I = I₀ * e^-μx
where
I = final intensity after passing through material
I₀ = initial intensity
μ = linear attenuation coefficient (m^-1)
x = thickness of material (m)

Example Calculation:
If the initial gamma intensity is 500 W/m² and it passes through a 0.02 m thick lead barrier with an attenuation coefficient of 0.5 m^-1, calculate the final intensity.
Solution:
I = 500 * e^{-0.5 * 0.02} ≈ 500 * e^-0.01 ≈ 495 W/m²

Module 3: Half-Value Layer (HVL) of Gamma Radiation

The Half-Value Layer (HVL) is the thickness of a material needed to reduce gamma radiation intensity by half, used in radiation shielding.

Formula:
HVL Calculation:
HVL = ln(2) / μ
where
HVL = half-value layer (m)
μ = linear attenuation coefficient (m^-1)

Example Calculation:
For a material with an attenuation coefficient of 0.693 m^-1, calculate the HVL.
Solution:
HVL = ln(2) / 0.693 ≈ 1.0 m

Note: HVL varies depending on material type and gamma ray energy, which is crucial in designing shielding for radiation protection.