Hello! I haven’t found some device specifications, so I would like to clarify (for H3D H420 with Isotope Activity Analysis in Visualizer Software ):
- what the аctivity measurement accuracy is for different sources and geometry, and what the аctivity measurement range is?
- is there any documentation about those specifications?
Dskulyar,
Sorry for the delay in responding. My name is David and I am an engineer at H3D. The answer is somewhat complex so I will answer piecewise w/ bullets.
- Isotope-specific accuracy: Without a unit specific calibration, accuracy is limited to the efficiency spread observed across many H420s. I.E. the efficiency curve defined on modern H420s is the average of many H420s, not matched to a specific unit. To the first order we have observed +/- 10% fluctuations in unit-specific efficiency. After a unit-specific efficiency calibration I would conservatively expect agreement to within 5% on well-resolved peaks. Note that uncertainty in source-to-detector distance and shielding density/atomic number readily eat into this margin.
- Activity range: Low activity, or high object shielding, quantification we will be Poisson (counting statistics) limited like any other detector. At the high-end we lose photopeak counts due to pileup, causing us to underreport efficiency: I observed a 10% underreporting of Cs137 activity when measuring at 40 mR/h.
These specific issues are documented in detail in an upcoming whitepaper. Please email me at dgoodman@h3dgamma.com for a copy.