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At a minimum you need to be able to measure ambient radiation by type:

Sievert - Wikipedia, the free encyclopedia

Equivalency Weighting Factors[1] Radiation type and energy range Factor
electrons, positrons, muons, or photons (gamma, X-ray) 1
neutrons <10 keV 5
neutrons 10-100 keV 10
neutrons 100 keV - 2 MeV 20
neutrons 2 MeV - 20 MeV 10
neutrons >20 MeV 5
protons other than recoil protons and energy >2 MeV 2
alpha particles, fission fragments, nonrelativistic heavy nuclei 20
 
How are you going to do that "without a custom ready shiny instrument"?

Economics is politics by other means
by Migeru (migeru at eurotrib dot com) on Mon Apr 4th, 2011 at 06:25:41 AM EST
[ Parent ]
So the Sievert is an estimate of the damage done by some combination of radioactivity present in an environment, and the accuracy of this estimate depends strongly on the degree to which various sources of that radiation is incopropated INTO living organisims?

"It is not necessary to have hope in order to persevere."
by ARGeezer (ARGeezer a in a circle eurotrib daught com) on Mon Apr 4th, 2011 at 11:05:37 AM EST
[ Parent ]
Yes here they're telling you that the cross-section of interaction of neutrons with living tissue is largest between 100 keV and 2 MeV.
neutrons 10-100 keV 10
neutrons 100 keV - 2 MeV 20
neutrons 2 MeV - 20 MeV 10
Which sort of makes sense: extremely energetic neutrons, being neutral particles, will just whizz past living matter having a shorter time to interact with atomic nuclei, while low-energy neutrons will have a low penetration depth.

But the specific numerical factors must have been determined empirically though who knows what procedures.

Rolf Maximilian Sievert - Wikipedia, the free encyclopedia

Professor Sievert (Swedish pronunciation: [ˈsiːvəʈ]) was born in Stockholm, Sweden. He served as head of the physics laboratory at Sweden's Radiumhemmet from 1924 to 1937, when he became head of the department of radiation physics at the Karolinska Institute. He played a pioneering role in the measurement of doses of radiation especially in its use in the diagnosis and treatment of cancer. In later years, he focused his research on the biological effects of repeated exposure to low doses of radiation. In 1964, he founded the International Radiation Protection Association, serving for a time as its chairman. He also chaired the United Nations Scientific Committee on the Effects of Atomic Radiation.

He invented a number of instruments for measuring radiation doses, the most widely known being the Sievert chamber.



Economics is politics by other means
by Migeru (migeru at eurotrib dot com) on Mon Apr 4th, 2011 at 11:10:36 AM EST
[ Parent ]
How are you going to do that "without a custom ready shiny instrument"?

To put it in other way, how can you verify what the "custom ready shiny instrument" is saying with more basic means? Do you know other measurements that are comparatively hard to replicate independently?  

by das monde on Mon Apr 4th, 2011 at 10:43:44 PM EST
[ Parent ]
To put it in other way, how can you verify what the "custom ready shiny instrument" is saying with more basic means?

If you trust that the manufacturer is not completely full of shit, you can read the specifications to see whether it is capable of doing what you want it to do.

If you're just looking at one on TV, you have no way to reassure yourself that it does what the newsies claim it does. Even if the manufacturer is honest (which he usually is), and even if the newsie understands the difference between a dosimeter a Geiger counter (which he usually doesn't), the TV format is not conducive to providing verifiable facts.

When I see something measuring radiation on TV, I tend to assume that it's a Geiger counter, because those are sufficiently useful that you want them around and sufficiently simple (and cheap) that they can be issued in bulk. They also make better TV than dosimeters, because Geiger counters go click-click-click, while dosimeters are quiet until they tell you to haul ass (and a newsie won't be allowed to come along if there's even a remote chance that the dosimeter will tell him to haul ass at some point during the show). Geiger counters measure Becquerel, however, and any conversion from Bq to Sv/h must necessarily rely on some pre-set assumptions about the distribution of radioactive atoms and the ratio between ambient and internal exposure.

As a practical matter, you use the Geiger counter to tell whether you are in one of four kinds of situation:

  1. Safe, so far.

  2. Leave as soon as practical.

  3. OMFG GTFO NOW!

  4. You'll be dead within the hour anyway. Might as well get the job done while you're here.

You don't need three significant figures to make that distinction.

Do you know other measurements that are comparatively hard to replicate independently?

Oh, lots. Particulate pollution levels and pollen readings, just off the top of my head.

What I can not recall off the top of my head is one that combines this level of obscurity with quite so strong vested interests.

- Jake

Friends come and go. Enemies accumulate.

by JakeS (JangoSierra 'at' gmail 'dot' com) on Mon Apr 4th, 2011 at 11:46:23 PM EST
[ Parent ]

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