Table 2 γ-rays and fast neutrons shielding parameters obtained and used for the radiation shielding assessment of the aluminum alloys understudy.

Linear attenuation coefficient (µ) in cm⁻¹

\(\:\mu\:=\frac{\Delta\:\text{l}\text{n}\left(I_x/I_0\right)}{\Delta\:x}\)

where I₀ is the initial beam intensity, I_x is the uncollided beam after passing thickness x of the shield.

It is a characteristic shielding parameter that assesses a shield’s capability to attenuate energetic photons, X-rays, and γ-rays.

Fast neutrons removal cross-section (Σ_R) in cm⁻¹

\({\textstyle\sum_R}=\sum\limits_1^n\rho_sw_i{\left({\textstyle\sum_R}\rho\right)}_i\)

where ρ_s and ρ_i are respectively, the shield density, and the density of the i^th element that constitutes the shield.

It is a characteristic shielding parameter that assesses the capability of a shield to remove fast neutrons from the incident beam.

Half value layer (HVL) in cm

\(\:HVL=\frac{ln2}{\mu\:}\)

The required shield thickness to attenuate 50% of the coming radiation (energetic photons or neutrons).

Tenth value layer (TVL) in cm

\(\:TVL=\frac{ln10}{\mu\:}\)

The required shield thickness to attenuate 90% of the coming radiation (energetic photons or neutrons).

Mean free path (MFP) in cm

\(\:MFP=\frac1{\mu\:}\)

The average distance that can be traveled by the energetic photon in the shield without making any interaction.

Relaxation length (λ) in cm

\(\lambda\:=\frac1{\sum_R}\)

The average distance that can be traveled by the fast neutron in the shield without making any interaction.

Radiation protection effectiveness (RPE) in %

\(RPE=\left(1-\frac{I_x}{I_o}\right)\times100\)

Itis an important statistical parameter to take into account when determining the level of attenuation that could be provided by the shield.