Monthly Archives: August 2011

Alpha Radiation, Geiger Counters 101 Part Two

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Alpha radiation was first detected in the late 19th century by Ernest Rutherford. Alpha radiation is the release of two protons and two neutrons with many millions of electron volts of kinetic energy! Alpha radiation is very positivity charged and cannot readily move more than a few centimeters from a source before tuning into normal helium. As a result, alpha radiation is only dangerous when inhaled, ingested, or otherwise allowed into the body.

Three more videos are coming!
Beta Radiation, Geiger Counters 101 Part Three
Gamma and X-Ray Radiation, Geiger Counters 101 Part Four
Radiation Math, Geiger Counters 101 Part Five

Important Websites:

Radioactive Units – Do Not Use Them Incorrectly!

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Geiger counters count ionizing radiation events.

To measure a detected reading, the energy of the detected radiation must be known. If the detected radiation has an unknown energy, there can be no measure, but merely the detection.

Examples of different energies from common isotopes released by Fukushima (approx):
Cs137 — 0.5 MeV beta
Cs137 — 1.1 MeV beta
Cs137 –Ba137m — 0.6 MeV gamma (often used to calibrate GM’s)
Sr90 — 0.5 MeV beta + weak gamma
I131 — 333 KeV beta
I131 — 606 KeV beta
U238 — 4MeV alpha

As you can see, the energies very quit allot and cannot be assumed.

Here are some energy dependent units:
1 Gray = 1 joule / 1kg
1 Seivert = 1Gy x RadiationFactor x BodyPartFactor
1 RAD = 0.01 joule / 1kg
1 REM = 1 Rad x RadiationFactor
1 Roentgen = = 2.58×10^-4 Coulomb / 1kg

As you can see… each of these units uses a degree of energy. You do not know the energy unless you know the exact nature of your source. As a result, you cannot use them.

In short: If and only if you know the exact energy of your source and a specific calibration and calibrated geometry, you cannot accurately use any energy dependent unit. All such unit measures are meaningless in these cases.

Use Counts Per Minute (CPM) or Counts Per Second (CPS)

Have fun!

New Radioactive Depression Glass Peice!

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I bought both of these peices at a local store in my town for under $20 each!

Depression Glassware, Vaseline Glassware, and other interesting glassware from the early to mid twentieth century where coated with, glazed with, or contained Uranium Oxide as a colorant. The Uranium Oxide created a brilliant green color, and could be mixed with other chemicals to make other powerful and rich colorings.

Depression, Uranium containing, glassware is generally safe to handle. Remember to keep it away from children and do not store it in a room where people frequent. Keeping it a few feet away from most people in an under-used room is often safe. Tip: Use a blacklight hidden behind the glass to make it look beautiful!

Uranium Oxide is mostly fertile U-238, sometimes with a tiny touch of fissile U-235, which is naturally occurring. The radioactive decay mode is an alpha particle with about 4.26 million electron voltes of energy! The alpha travels but a few inches from the object before gaining electrons and possibly releasing additional radiation through secondary ionization. The secondary decay is a gamma ray at about 49.55 kilo-electron volts. In reality, the full decay series and total emission band is much more complex.

Geiger Counters 101 — The Basics, Part One

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Part one of the Geiger Counters 101 series, by, covers the basic history, usage, and aspects of Geiger Counters. The following topics are covered in the first part:

The history of the Geiger-Mueller tube
Basic Geiger tube concepts
New Geiger counter? What do you do?
Taking a baseline/background reading
various tips and tricks.

There are no prerequisites other than you have an interest in radiation and Geiger counters.

Five things to remember:
(1) Always use CPM (Counts per minute) unless you are calibrated for the specific, known, element and radiation source you are detecting.
(2) There are four common ionizing radiation types: Alpha, Beta, Gamma, and X-Ray.
(3) A Geiger Counter which is turned off detects NOTHING. Keep your unit on and stay informed.
(4) You cannot check too slowly. Do not rush your examinations of objects.
(5) Identify and monitor your baselines. A reading without a baseline is of little use.