Revision 1

Accepted · first revision · record

Title: Absolute dosimetry at ultra-high dose rate
Plain: Standard dose meters saturate when the dose arrives in a single very intense pulse, because the charges they collect recombine before being counted. There is no accepted way to measure such doses absolutely.
Precise: Establish traceable absolute dosimetry for pulses delivering 100 to 1000 rad in 1 to 4 microseconds, with instantaneous dose rates up to $10^9\,\mathrm{rad}/\mathrm{s}$, where ion-chamber general recombination is severe and the Boag formalism (the standard correction for charge recombination in ion chambers) fails. Candidate standards: water and graphite calorimetry, Fricke and alanine chemical dosimeters, scintillator and Cherenkov detectors. An answer is a primary standard plus validated transfer detectors with uncertainty below 2 percent.
Settled by: Agreement within 2 percent between calorimetric primary standards and transfer dosimeters across the pulse-structure range.
Kind: well-posed
Answer type: value
References: (empty)
Literature status: open
Status note: Calorimeter-based ultra-high dose-rate standards were under development at several national laboratories as of 2025.
Posed since: 2018