GEIGER COUNTER £295.00
SCROLL DOWN FOR A NON-TECHNICAL ARTICLE ABOUT RADIOACTIVITY AND ANTIQUES
To buy this item click Geiger Counter
QUICKTEST GEIGER COUNTER Data Sheet
This radiation monitor has a single control switch which provides on/off, battery check and internal sounder on/off option.
The ratemeter is a high quality Anders moving coil instrument calibrated in counts/sec. with about a +/- 1.5 % accuracy.
The unit has a very low power consumption and the 3 AA cells provide some
thing like 200 hrs. continuous use.
The ratemeter covers a range of 0 to 700 counts per sec. and is calibrated in
counts per sec.
The Geiger counter used is a standard D.N212 organically quenched tube fitted
with a nominal 50 mm. dia.mica window.
The window weight is 2 mgm. cm. –2. The
Geiger probe is fitted with a high transmission stainless steel protective grill.
The background count rate is less than 1 c.p.s.
| Radiation | Typical
sensitivities (cps/Bq.cm.-2) |
Source | Max. energy (MeV) |
| Alpha | 1.3 | 241 Am | 5.49 |
| Beta | 3.6 | 90 Sr/ 90y | 2.27 |
| 3.3 | 204 TI | 0.77 | |
| 1.5 | 147Pm | 0.23 | |
| 1.0 | 14 C | 0.16 | |
| Gamma | 7 (cps/microGy.h-1 | 137 Cs | 0.66 |
Individual calibration certificates are supplied with each instrument.
The instrument is supplied complete ready for use
TESTING ANTIQUES FOR RADIOACTIVITY
Michael
manufacturers radiation meters, Geiger counters.
And so two obvious questions: How much do they cost? and Can they be used
for testing antiques?
The answer
to the first question (cost) was interesting. Until recently any Geiger counter made to modern Western scientific
standards cost over £400.00 but Michael had just developed a new Geiger
counter that would sell for just £295.00...and I shall now call it The
QUICKTEST Geiger counter. Please
do not confuse these with the black-market Russian Geiger Counters I had
a few years ago for £20.00, nobody knew what the measurements on the scale
meant, nobody knew if they worked properly, they were no more than collector's
curios in the aftermath of Chernobyl.
The
answer to the second question (testing antiques) soon became obvious.
Nobody has ever used a Geiger counter in the antiques trade.
The
use of a Geiger counter is twofold. To
find out if an item is hazardous irrespective of any antique value;
and to find out if an item is genuine irrespective of any hazard.
RADIOACTIVITY - THE READINGS AND THE HAZARDS
The following
numbers are c.p.s. (counts per second), as a measurement of 'health hazard'
they represent relative risk, if you are of the opinion that there is
no 'safe' level of radioactivity it would be best to avoid anything with
a reading above 2 c.p.s.
1 to
2: natural
background level (good reading - shows Geiger counter is working properly)
3 or
4: slightly above background level
5 to 10: even at these low levels an item (e.g. watch)
should not be kept next to skin for prolonged periods
10 to 100: do not carry the item next to the skin at all
100 to 200: do not to carry item close to your body, just handle it very
occasionally
200 to 500: best not to handle
the item at all
I must stress that any reading above 2 c.p.s. indicates only an approximate and relative risk, there is no significance, for instance, in the reading being just below 200 or just above 200.
Radioactive substances
are referred to, colloquially, as 'hot'. This is not a coincidence.
Radioactivity does behave like heat.
An analogy
(and just an analogy): you can feel a strong (hot) heat source on your
skin, and the closer you get the hotter it feels, but as you move away
the feeling of heat diminishes rapidly.
The same applies to a radioactive source, a high reading against
the source may frighten you, but now move the item away from the Geiger
counter a few inches and the reading might drop to background level. Turn the item (e.g. a watch dial) upside down, is there a reading
through the movement and back? If
not, then no radioactivity will reach your skin through the back of the
watch. Also, the human body
varies in susceptibility, extremities (hands, fingers) are less at risk,
the torso (chest, heart) is more at risk.
Using the QUICKTEST Geiger counter you can now make a decision:
would you hang the watch around your neck with the dial facing your skin? Would you wear it on your wrist?
Would you prefer to keep it in the back of a draw?
The
same applies to other radioactive items: would you want to keep a vase made of
Vaseline Glass (Uranium Glass) on a bedside table three inches from your face,
or would you prefer to place it at the back of a display cabinet?
Do you need to remove that box of old
gas mantles from under the livingroom table to the loft, or would they be better
removed from the house altogether?
RADIOACTIVITY AND TESTING ANTIQUES
Dials
When
radium was discovered it was like 'magic' - a paint that glowed
in the dark, didn't need batteries, didn't even have to be 'charged up'
with a strong light (as with fluorescent substances). The girls in the
factories who painted the dials would keep their paintbrushes moist by
licking them. They died. The
most dangerous paints were discontinued in 1945.
On some old dials the reading on the QUICKTEST Geiger Counter slowly
creeps up to 20 or 30, one dial (which a customer sent me to test) shot
up to 500 and even showed a significant reading from a few inches away.
Vaseline (Uranium) Glass
The
reading on the QUICKTEST Geiger Counter will move steadily up to 50 or 100,
sometimes it rapidly rises to 200 or 300.
Gas Mantles
These
were made from a highly radioactive material, though not on purpose, nobody at
the time knew that they were radioactive. Michael
once took a Geiger counter to a small antiques shop that had several dozen old
gas mantles - the entire shop was 'hot'!
Gemstones
Zircon is naturally radioactive, some gemstones are irradiated to change their colour. The QUICKTEST Geiger Counter is not sensitive enough to detect these.
Anything Else?
If you have any experience in this area or can recommend any good links, please contact me at raffi@quicktest.co.uk
