# Quantum Effect on Calibrating a Dosimeter? **URL:** \ **Category:** Factual Questions\ **Created:** [April 20, 2021, 3:04am UTC](https://boards.straightdope.com/t/quantum-effect-on-calibrating-a-dosimeter/940349 "2021-04-20T03:04:31Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![Jinx](https://avatars.discourse-cdn.com/v4/letter/j/c6cbf5/32.png) [@Jinx](https://boards.straightdope.com/u/Jinx)\ **Post date:** [April 20, 2021, 3:04am UTC](https://boards.straightdope.com/t/quantum-effect-on-calibrating-a-dosimeter/940349/1 "2021-04-20T03:04:31Z")
Can devices that count subatomic particles, such as dosimeters, Geiger counters, and the like really be calibrated? I am wondering if quantum effects come into play here leading to inconsistent results when trying to calibrate? Are there any rules of thumb here about how to know when one should account for quantum physics when working with such devices? In addition to your feedback, any links that are good references would be appreciated ---
**Author:** ![si\_blakely](https://avatars.discourse-cdn.com/v4/letter/s/d9b06d/32.png) [@si\_blakely](https://boards.straightdope.com/u/si_blakely)\ **Post date:** [April 20, 2021, 3:43am UTC](https://boards.straightdope.com/t/quantum-effect-on-calibrating-a-dosimeter/940349/2 "2021-04-20T03:43:48Z")
The outcomes from the interactions of sub-atomic particles form a statistical distribution - calibration of detection devices just ensures that the statistical distribution recorded by the detector matches the distribution of a known calibration sample - usually a source containing an isotope with a very long half-life and sufficient activity to match the appropriate range for the detector. It’s much harder when interactions occur at a low level, and generating said particles is difficult - neutrinos, for example. The detectors are huge, with large numbers of delicate photomultiplier tubes, and (when they were first being set up) no-one was actually sure about the interaction distribution and required sensitivity. And the vast majority of the detected neutrinos are from the sun, so spotting non-solar neutrinos is that much harder. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [April 20, 2021, 10:44am UTC](https://boards.straightdope.com/t/quantum-effect-on-calibrating-a-dosimeter/940349/3 "2021-04-20T10:44:09Z")
The major “quantum effect” relevant is going to be simple shot noise (which can occur with purely classical systems as well). Basically, you’re counting discrete events, and so it’s possible, by random chance, that you’ll get more or less of them than you expect. It’s like asking how many four-leaf clovers you’ll find in a field: You can get an expected number, but you might get more or less lucky. But the error from this is approximately the square root of the number of events, so if you’re calibrated for tens of thousands of events, you’ll get an error of less than a percent. ---
**Author:** ![Jinx](https://avatars.discourse-cdn.com/v4/letter/j/c6cbf5/32.png) [@Jinx](https://boards.straightdope.com/u/Jinx)\ **Post date:** [April 21, 2021, 11:29pm UTC](https://boards.straightdope.com/t/quantum-effect-on-calibrating-a-dosimeter/940349/4 "2021-04-21T23:29:08Z")
So, suppose one is attempting to calibrate a batch of devices and the results for any one of these device are wonky - sometimes acceptable and sometimes not acceptable. Is this a manifestation of the uncertainty principle (or other aberrations of the quantum world) or simply a case of defective equipment? ---
**Author:** ![Jinx](https://avatars.discourse-cdn.com/v4/letter/j/c6cbf5/32.png) [@Jinx](https://boards.straightdope.com/u/Jinx)\ **Post date:** [April 21, 2021, 11:35pm UTC](https://boards.straightdope.com/t/quantum-effect-on-calibrating-a-dosimeter/940349/5 "2021-04-21T23:35:01Z")
^By “any one of these devices”, I mean if you pick up any one of these devices to calibrate multiple times and each time it’s a coin toss if the results will be acceptable or not. ---
**Author:** ![naita](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/naita/32/5862_2.png) [@naita](https://boards.straightdope.com/u/naita)\ **Post date:** [April 22, 2021, 2:34pm UTC](https://boards.straightdope.com/t/quantum-effect-on-calibrating-a-dosimeter/940349/6 "2021-04-22T14:34:23Z")
> [@Jinx](#): > > Is this a manifestation of the uncertainty principle (or other aberrations of the quantum world) or simply a case of defective equipment? The latter.