Guide: from source settings to a reported result
Field Pro · updated 28 October 2026
The workbench takes a reference field from its source settings to a number you can put in a calibration record. This page follows the screen in the order you fill it.
How the screen is laid out
On a wide screen the inputs sit on the left (panels 01–04) and the results on the right (the spectrum chart and panels A–D). Below 980 px the two columns become an Input tab and a Results tab, with the calculate bar fixed to the bottom edge. Every panel title is also an address: #source, #geometry, #readout and #repeatability for the inputs, #spectrum, #characteristics, #operational, #iso and #uncertainty for the results. Such a link opens the right tab at that panel, and Back steps through the panels you visited.
Filling in the four input panels
01 Source
Pick X-ray tube, Cs-137, Co-60 or Import. For a tube, the ISO beam quality list holds all 50 qualities of ISO 4037-1; choosing one fills in the tube voltage, the filter stack and a 2500 mm air path. Edit any of them and the list shows Custom (edited), so a modified beam never carries a standard name. Tube voltage runs from 10 to 400 kV; filter layers can be Be, Al, Cu, Sn, Ta, W or Pb, and the first row is tagged Inherent. For a nuclide, enter the certificate activity in MBq or GBq, the certificate's reference date, the date of the measurement and the distance in metres. Import takes a spectrum as two columns, energy and fluence, separated by commas, tabs or spaces.
02 Geometry and evaluation
The angle of incidence α (0–75°) applies to Hp(10) and H′(0.07); H*(10) is isotropic and ignores it. Leave HVL material on Auto: the half-value layer is then given in the material of the matched ISO quality. The ISO comparison target is auto-matched by default, and the tolerance band starts at ±5%.
03 Readout correction
Enter one chamber reading with the temperature, pressure and relative humidity at the time. The workbench returns kρ, the factor that refers a vented chamber to 20 °C, 101.325 kPa and 65% relative humidity.
04 Repeatability uncertainty
Paste repeat readings separated by spaces, commas or line breaks. With Apply kρ ticked, each reading is multiplied by the panel 03 factor first. Type B components below them are relative standard uncertainties in percent; the first is a 1.0% entry for the reference chamber's certificate.
Calculate or auto-calculate
The workbench starts in manual mode. When an input changes, the button turns into Calculate — inputs changed and the result panels keep showing the previous calculation under a notice, so you never read a half-updated set of numbers. After you press it, each readout shows the change from the previous calculation with ▲ or ▼. Switch on Auto-calculate to update while typing; that choice and the inputs themselves are kept in this browser for your next visit.
Reading the results
- Spectrum. Relative fluence against energy. The Kerma button overlays φ·E·(μen/ρ), the share of air kerma per energy.
- A Beam-quality characteristics. Mean energy Ē, effective energy Eeff, HVL1, HVL2, the homogeneity coefficient h = HVL1/HVL2 and the air-kerma transmission of the added filtration. With the default N-80 inputs HVL1 reads 0.5753 mm Cu.
- B Operational dose conversion coefficients. Hp(10, α) on the ICRU slab, H*(10) and H′(0.07, α) in Sv/Gy. Multiply the air kerma you measured by these to get the conventional dose equivalent. For a nuclide this panel also gives the point-source air kerma rate, and it shows kρ.
- C ISO 4037-1 comparison. The matched quality with its tabulated HVL1, HVL2, homogeneity coefficient and mean energy, the calculated values, the deviation and a Within band or Outside band verdict for each.
- D Measurement uncertainty. From two readings up: the Type A evaluation, the combined budget and the Reported result, value ± U with its coverage factor.
Saving, loading and printing
Save session downloads a JSON file holding every input; Load session restores it on any computer. Print report lays out the input conditions and all result panels on paper with the print date. Reset returns every field to the N-80 defaults after a confirmation. Two address parameters open the workbench in a given state: ?preset=N-80 (any quality name) and ?source=Cs-137.
Mistakes that change the answer
- Fixing the HVL material by habit. H-60 is tabulated in aluminium although it runs above 50 kV; a copper HVL cannot be compared with it. Auto follows the table.
- Judging a quality at the wrong distance. Panel C always uses the table's 2.5 m column, so keep the air path at 2500 mm when you judge a quality. At N-80 the distance hardly matters (0.578 against 0.580 mm Cu at 1.0 and 2.5 m), but H-10 is tabulated at 0.044 and 0.059 mm Al: the air in between is the main filter.
- Carrying the Type A factor into the combined result. Five readings give k = 2.776 for repeatability alone; once a 1% certificate component joins, the effective degrees of freedom rise to about 821 and k falls to 1.96. The uncertainty example shows the numbers.
- Correcting twice. If your readings are already temperature- and pressure-corrected, untick Apply kρ.
- Leaving the evaluation date on the certificate date. A Cs-137 source loses 2.3% of its activity per year; the Cs-137 example works through ten years of decay.
The N-80 example runs a complete X-ray field from these panels, and Methods explains what each number is computed from.
Sources
- ISO 4037-1:2019, Part 1: Radiation characteristics and production methods — quality list, HVL material of H-60, HVL1 of N-80 and H-10 at 1.0 m and 2.5 m.
- JCGM 100:2008, Guide to the expression of uncertainty in measurement, G.3 and G.4 (coverage factor and effective degrees of freedom).
- IAEA Nuclear Data Section, Live Chart of Nuclides: Cs-137 half-life 30.08 a.
- Screen behaviour as implemented in the workbench source.