Flux, Fluence, and Dose Metrics
Flux, fluence, and dose describe how strongly and for how long something is irradiated; clear metrics make neutron service data comparable and defensible.
Getting the units right
Radiation service data is only useful if the exposure is quantified precisely. Three quantities do most of the work. Flux is the number of neutrons crossing a unit area per second. Fluence is flux integrated over time, the total neutrons per unit area. Dose, in a material sense, is the energy or damage deposited, often expressed as dpa for structural work.
Why each matters
- Flux sets the rate; high flux shortens a campaign
- Fluence sets the total exposure a sample has seen
- Dose or dpa links exposure to material or device response
- Spectrum qualifies all of the above; 14 MeV must be stated
Reporting discipline
A credible neutron service reports flux, integration time, resulting fluence, the neutron spectrum, and the sample temperature. Without those, a dpa number is ambiguous. Kronos treats reproducible, fully specified exposure records as the deliverable of a materials or electronics campaign.
Because the breeder runs at a defined design point, its flux at a test position can be characterized and held stable, which is what makes fluence targets meaningful.
Where errors creep in
Most disputes over irradiation data trace back to poorly known fluence or an unstated spectrum, not to the physics of the material. Flux can vary across a test volume, so a sample's true fluence depends on exactly where it sat. Careful services map the flux gradient, place dosimetry foils alongside the samples, and report position-resolved fluence. Getting these details right is unglamorous, but it is the difference between a defensible dataset and a number nobody can reproduce.
This is a public overview only. It contains no classified information, no operational detail, and no weapons-design content.