Effects of Temperature on Cross Section

As discussed, the microscopic absorption cross section varies significantly as neutron energy varies. The microscopic cross sections provided on most charts and tables are measured for a standard neutron velocity of 2200 meters/second, which corresponds to an ambient temperature of 68^oF. Therefore, if our material is at a higher temperature, the absorption cross section will be lower than the value for 68(F, and any cross sections which involve absorption (for example, σ_a , σ_c , σ_f ) must be corrected for the existing temperature.
The following formula is used to correct microscopic cross sections for temperature. Although the example illustrates absorption cross section, the same formula may be used to correct capture and fission cross sections.

where:
σ = microscopic cross section corrected for temperature
σ_o = microscopic cross section at reference temperature (68^oF or 20^oC) 
T_o = reference temperature (68^oF) in degrees Rankine (^oR) or Kelvin (^oK) 
T = temperature for which corrected value is being calculated

NOTE: When using this formula, all temperatures must be converted to ^oR or ^oK.

^oR = ^oF + 460
^oK = ^oC + 273