Geiger Counter Gammascout
The Gammascout Geiger Counter is a calibrated measurement instrument for alpha, beta and gamma rays.
In a PELI Case 1040 (+heavy metal for taring, Cd for neutron detection) it can be used for underwater measurements down to
5 m water depth.
For greater depths i use a cheap
water filter case (+lead metal for taring and two plugs for the input
and output and some silicia gel) for underwater measurements down to
100 m water depth:
The central processor of the Gammascout is a MSP430.
The USB version uses a FT232BM
for the conversion USB to UART for the MSP430.
The hardware is good, but the software not: For a plot of the
measured and read
values (dose rate/count) you first have to use the Calculate-button and than
you find a button for show; the Display-Button shows only a log.
The program does not store the parameters, e. g. 2d plot of the dose
with no numerics, it can't be terminated via Alt-F4, on my
Notebook with a CoreDuo T2050
(1,6 GHZ, 1 GB RAM, MS-WinXP Prof. ) it needs 1 minute to start (every
Quake game
starts much faster) and sometimes the mouse
pointer is invisible in the program window. For clearing the
gammascount memory you have to read out the memory, even if you
have done so one minute ago, and the program can use only one of
the first (virtual) ten serial ports which are
often already used by a bluetooth driver.
The data sheet of the geiger tube
LND 712
says that with a shielding consisting of 50 mm Pb and 3 mm Al
the maximum CPM rate is 10 CPM. Because with 20 CPM the dose rate shown by the Gammascout is about
0.2 µSv/h, this means the dose rate caused by the hard
cosmic rays,
which can pass the 50 mm Pb + 3 mm Al shielding, is about 0.1 µSv/h.
The gamma sensitivity shows that the saturation dose rate is about
10 mSv/h, at a pulse rate of 10 kHz.
So you can't measure much less than 0.1 µSv/h and not more then 10 mSv/h with
the Gammascout. It's the same with replacement types like the ZP1401.
Another restriction are that a geiger tube commonly detects only about 5 % of
all incoming rays and that the Gammascout shows the dose rate for "common" radiation
(gamma from 60Co), with the radiation weighting factor of 1,
but the radiation can have a higher factor and the Gammasout can be
less sensitive. Examples are low-energy alpha and beta rays which can't
get into the tube and therefore can not be detected, but they have a high
radiation weighting factor.
The
LND 712 data sheet
says nothing about the lifetime,
but a typical geiger tube lifetime is 10 billion pulses, which
is, at the usual activity of 20 pulses per minute,
951.3 years. Because of the flash memory of the
MSP430 the effective life time limit is about 30
years (minimum), when you change the battery every 10 years.
The lifetime of the MSP430 can be extended by re-flashing the firmware via the JTAG
interface connector (close to the left side of the MSP430).
Another restriction is the size of the internal flash memory: If the logging
interval is set to one hour, it is full after four weeks.
The size is 163 x 71 x 30 mm, the
2011 price of the LN 712 is about 88 Euro, but it is not availible
before 2012, because it is sould out after the Fukushima Daiichi nuclear disaster:
http://www.meggys-shop.de/Geiger-Mueller-Zaehlrohr-LND-712
and the price of the simple Gammacout is about 300 Euro:
http://www.heise.de/preisvergleich/a622518.html.
Some measurement results
| Indoor dose rate in Germany, Nuremberg (300 m AMSL) and also in Aalen: |
185 ± 50 nSv/h |
| Outdoor Dose rate in Germany, Nuremberg, 4.5 m underwater (
Freibad Stadion and PELI case 1040): |
about 90 nSv/h |
| Indoor Dose rate in Germany, Nuremberg, 30 cm underwater: |
160 ± 50 nSv/h |
| Indoor dose rate in Germany, Mülheim (100 m AMSL): |
230 ± 50 nSv/h |
| Indoor dose rate in Germany, Bremervörde (4 m AMSL): |
170 ± 50 nSv/h |
| Indoor dose rate in Hongkong (10 m AMSL): |
400 ± 50 nSv/h |
| Indoor dose rate in Taipei (100 m AMSL): |
195 ± 50 nSv/h |
| Indoor dose rate in Tanzania, Dar es Salaam (10 m AMSL): |
130 ± 50 nSv/h |
| Indoor dose rate in Tanzania, Moshi (900 m AMSL): |
280 ± 50 nSv/h |
| Dose rate from 15 g potash directly under the gammascout and 200 g salt with 50 g K above: |
25 ± 50 nSv/h (total dose rate: 210 ± 50 nSv/h)
|
|
| Dose rate from 200 g potash directly under and above the gammascout : |
100 ± 50 nSv/h (total dose rate: 285 ± 50 nSv/h)
|
|
| Dose rate from 1 kg potash directly around the gammascout : |
220 ± 50 nSv/h (total dose rate: 405 ± 50 nSv/h) |
| Dose rate from radioluminescent keychains (Glow Rings) with
Tritium Illumination or from 100 ml heavy water: |
0 ± 50 nSv/h (the soft beta radiation can't get out of the
housing and maybe not into the geiger tube)
|
|
|
| Dose rate from about 2 g RbCl (0,283 MeV β emission from
87Rb), placed on the window of the tube: |
200 ± 50 nSv/h (total dose rate:
385 ± 50 nSv/h)
|
|
| Dose rate in an art deco uranium glass vase from about 1925,
with a weight of 800 g, 20 cm height and 14 cm diameter |
about 0.7 µSv/h
|
|
| Dose rate close to an opened alarm clock with radium paint from the middle of the 20th century: |
about 7 µSv/h
|
|
| Dose rate close to three gas mantles with ThO2: |
about 12 µSv/h
|
|
| Dose rate close to 90 g UO2(NO3)2.6H2O: |
about 25 µSv/h
|
|
| Dose rate from a 49 kdpm 14C standard capsule, placed on the window of the counting tube: |
about 26 µSv/h
|
|
| Dose rate close to 50 g ThO2: |
about 120 µSv/h
|
|
|
Comments:
If not commented with about, the value is an average of minimum two 24 hour averages, measured 2006 or later.
The 50 g ThO2 are a good source of gamma rays which can be used
e. g. for testing Photomultiplier tubes
(photomultipliers or PMTs for short) without light and for testing geiger
counters and similar devices, but should be stored and transported with a
little shielding and, more important, distance.
The comic ray intensity is anti-correlated with the
sunspot
activity and has
therefore a period of 11 years, with a variation of 12 % around the average
value (Physik Journal, March 2007, p. 60). Because of
Solar flares,
there are also short-time fluctuations of the comic ray intensity.
Measurements of the cosmic ray variations can be found here:
http://www.durangobill.com/SwindlePics/SwindleCosmicRays.gif
http://www.brighton73.freeserve.co.uk/gw/solar/cosmic_rays.gif
http://science.nasa.gov/headlines/y2005/images/afraid/doserates.jpg
and in the cosmic ray variations sites chapter at
http://helios.izmiran.rssi.ru/cosray/main.htm#links
The common dose limit for an employee, which is considered as a harmless
dose rate, is 20 mSv/a, which is rounded 2.3 µSv/h and this is only about ten
times more than the common natural background at low altitudes and about one
hundred times more than the activity of the natural potassium content of the
human body or common food.
With a natural potassium content of about 1 % a food (not a medium as drinking water) or stone
has a natural activity of about 312 Bq/kg. Because potassium is only
one of dozens natural radioactive
elements, common food has a natural activity of about 500 Bq/kg.
Because water has a low natural activity,
dried food has a natural activity of several kBq/kg.
So food with with a too low radioactivity is not good, because this food
causes inadequate potassium intake and this causes
Hypokalemia.
Trip from Nuremberg to the highest summit of the Mount Kilimanjaro and back in 2007
Uhuru peak at 2008-07-14 (winter), at sunrise (6 am), Dose rate: 0.7 µSv/h,
Wind speed: 8 m/s, Air pressure: 495 hPa, Temperature: -7.4°C (wind chill
temperature: -24°C, but because the wind chill temperature does not take
into account the low air pressure, the effective wind chill temperature is
about -10°C).
The common death rate at Kibo is about 0.02 % and about 60 % of the
tourists
do get a certificate for successfully climbing Uhuru Peak (5895 m), which means
they climbed to Stella Point (5756 m) or higher.
The good trip organizing company was
Afromaxx. The trip did cost about 1000 US-Dollar, including one week
(one star) hotel.
Trip from Nuremberg to the summit of the Aconcagua and back in 2009
Due to a snowstorm with a sight distance of only 10 m, the summit was closed right
before the canaletta at approx. 6600 m height, but the 4 days at Plaza de Mulas
(PDM, 4365 m)
and Nido de Condores (NDC, 5560 m) on the Normal Route can clearly be seen in the
middle of the picture. You can also see the trip to Placa
Francia before and the trip to (nearly) the summit, from NDC. At the leap of half a day at PDM the
Gammascout had a blackout; it seems a "HOLD" key, which is blocking all (other)
key pressures, is missing.
You can also see the flights Munich-Madrid, Madrid-Santiago, Santiago-Mendoza
and back.
The dose rate was (0.1 ± 0.015) µSv/h per kilometer height at
Aconcagua and higher above, during the flights.
So it's possible to measure the height via the dose rate, without
problems like a blocked or locked pitot tube.
This also means that a good flight simulation chamber is incomplete
without X-raying of 0.1 µSv/hkm, but it seems no flight simulation chamber
has it.
At the Kibo trip the dose rate was a little higher during the flights and at
the same altitude. The reasons were:
The flights to/from Aconcagua where lower (10.5 km instead of 12.0 km maximum
height, as shown on the monitors inside the plane) and the ground at the Kibo
must have more radioactivity, not much less then the activity of
the cosmic rays. This is consistent with the fact that vulcanoes, and Kibo is a
vulcano while Aconcagua is not, usually have more radioactivity, because of
their higher Potassium content:
http://www.kreis-ahrweiler.de/kvar/VT/hjb2001/hjb2001.48.htm.
The reason may be that the heat of a higher concentration of radioactive
material deep inside the earth can produce a Hotspot, which produces vulcanos.
Temperature, air pressure, air humidity, and acceleration at the aconcagua
trip.
During that time at Aconcagua 10 people died, one survived seriously wounded
and one was lost:
The common death rate at Aconcagua is about 0.5 %
and some deaths can be found on youtube, e. g.
http://www.youtube.com/watch?v=j6WxFqu5jIE&feature=player_embedded.
Because the death rate at the highest mountains with an elevation above 8 km is
about 10 % (http://en.wikipedia.org/wiki/Eight-thousander), Aconcagua is relative
harmless. One reason for the low death rate at aconcagua is that you
have to get a medical check at the first camp (Confluencia) and the base camp (Place de Mulas), and if your
pulse rate, blood pressure or oxygen saturation is not ok you get send back.
About 30 % of the tourists make it to the summit.
The rate of severe nonlethal injuries at aconcagua is about 1 %, which is about two times the death
rate and also relative low.
The good trip organizing company was the austrian
Verkehrsbüro. The trip did cost a little more than 2000 Euro, including
all flights (with a baggage limit of 60 kg) and hotels.
The increase of the radiation dose with the altitude does not mean that the life expectancy is shorter; in facts it is longer:
http://circ.ahajournals.org/cgi/content/abstract/CIRCULATIONAHA.108.819250v1?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&fulltext=swiss&searchid=1&FIRSTINDEX=0&resourcetype=HWCIT,
german abstract:
http://www.dradio.de/dlf/meldungen/forschak/1006678/.
One reason is that such low radiation doses are biopositive; they are more stimulating than destroying.
Memorial at the chernobyl nuclear power plant. Dose rate: About 15 µSv/h.
I took a regular one-day journey from
http://chernobylzone.com
for only 122 US-Dollar (depends on the number of people which pay for the
english speaking guide; it's 162 for one), including supper and an english
speaking guide.
Individual and longer journeys are also available, with helicopter and a visit
inside the nuclear power plant, but significant more expensive.
Other also journey to Chernobyl organising companies are
www.tourchernobyl.com
,
www.newlogic.ua
, and
www.panorama-tour.info
.
You can find an overview for Chernobyl journeys at
http://wikitravel.org/en/Chernobyl.
In the diagram you can also see the flights Kologne-Kiev and back.
The diagram starts with steps of 10 minutes (violet) and after that it's with
one hour steps.
The results are nearly the same as described e. g. at
http://forum.pripyat.com
and
http://www.berger.ma/gallery_trip.php:
The radiation which you measure is about 90 % gamma, 9 % beta and 0.1 % alpha.
Most of the radiation is caused by Cesium-137, a little from Strontium-90
and very little from Plutonium, Americinum and some other elements/nuclides.
More than about 90 % of the radiation is caused by Cesium-137 and Strontium-90.
The dose rate i measured was:
0.20 ± 0.02 µSv/h at the hotel and in the center of Kiev
about 0.1 µSv/h in the Metro of Kiev
about 0.4 µSv/h in the central railway station of Kiev, maybe because of the
granite floor
about 0.25 µSv/h in the center of Chernobyl
about 15 µSv/h at the memorial close to the nuclear power plant, because the memorial and the street around it was build with material from outside the chernobyl zone, after the Chernobyl disaster
about 0.2 µSv/h at the railway bridge close to the nuclear power plant, where
you can feed the famous big fishes
about 0.1 µSv/h on a bridge over the Prypiat river near Chernobyl
usually 1, at some places 2 µSv/h on the streets of Prypiat
usually 2, at some places about 4 µSv/h in the forest in Prypiat
about 11 µSv/h in the bus, while passing the
Red Forest
about 0.2 µSv/h in the buildings in Prypiat
about 15 µSv/h at the first hotspot in Prypiat
nearly 35 µSv/h at the second hotsport in Prypiyat
nearly 900 µSv/h at the third hotspot in Prypiat.
Inside the bus the dose rate was about the half of the dose rate on the street.
More about the hotspots in Prypiat (also called Pripyat) can be found
here.
In 1986 the dose rate after the disaster was about up to 1,000,000 µSv/h in
Prypiat and about 10 times higher at the burning reactor, due to the
Chernobyl Museum in Kiev and other sources, but now
there is nothing dangerous, except close to the destroyed reactor or if you
stay a long time at the hotspots or high activity areas like the red forest or
eat animals or plants or drink water from there.
Another point is that a lot of the fallout is now deep in the earth and that's
the reason why in Chernobyl e. g. the teleheating tubes are above ground.
The dose rate at Prypiat has decresed
by a factor of about one million since the disaster.
Close to Prypiat the
Red Forest has a dose rate up to 60 µSv/h,
which is dangerous if you stay longer than a week, because commonly
a dose limit of 20 mSv/a (twenty milliSievert per year), which is at
average during a whole year rounded 2.3 µSv/h, is considered harmless.
A dose of 20 mSv, which is the dose caused by a
typical Neonatal abdominal CT scan
is harmless.
The most common long-term effect is cancer.
When 100 adult people get a dose of 100 mSv in a short period of time,
then at average one will get cancer, caused by the dose, during the
rest of his life:
http://www.dradio.de/dlf/sendungen/forschak/1445604/.
So the harmless dose of 20 mSv, caused by a typical Neonatal abdominal
CT scan, means that it causes at "only" one of 500 people cancer,
which is a relative low risk.
Radiation sickness symptoms do begin at 0.5 Sv and severe radiation poisoning
with 50% fatality after 30 days (LD 50/30) is at a dose of 3-4 Sv:
http://en.wikipedia.org/wiki/Radiation_poisoning.
And it takes about 2.5 times that dosage for the LD 50/30 of a chicken and
over 100 times that for the LD 50/30 of a cockroach.
At CT Brain Perfusion Scans the common dose is 0.5 S,
and 3 to 4 S at radiation overexposures, but only at one part of the body
(the head), so some CT scans do cause radiation sickness:
http://www.fda.gov/MedicalDevices/Safety/AlertsandNotices/ucm185898.htm
(with 1 Sv = 1 G for X-rays).
Another point is that beside the radiation sickness symptoms there are
other damages like a higher cancer and mutation rate. So if a radiation
exposure causes no radiation sickness symptoms it does not always mean that
it's harmless. Therefore a lower dose is better when the dose is higher than
20 mSv/a.
Because of the long-term effects, underage children should get a lower dose.
They should get less then one half of this dose, and because embryos are
additionally more sensitive, they should get less than one quarter of this
dose.
High dose rates at the chernobyl area of alienation can be found only close
to the destroyed reactor.
It has been reported that on the roof of the sarcophag the dose rate is
about 20,000 µSv/h (in 2006):
http://www.fen-net.de/dr.helmut.pfister/20%20Jahre%20nach%20Tschernobyl.pdf.
Beside the radiation effects another problem is the liability for such desasters: Many insurances do
not pay for radiation caused damages and in many countries the liability of the nuclear power plant
owner is limited very low, e. g. in Bulgaraia to 17 million Euro, Denmark 60 MEuro, France 84
MEuro, Slovakia 83 MEuro, Italy and Lithuania 5 MEuro, source
http://dip21.bundestag.de/dip21/btd/16/099/1609979.pdf.
So in case of a maximum credible accident like at chernobyl in most countries the victims will get no
or only very few compensation, even in rich countries.
The other data, temperature, air pressure, humidity and acceleration, are not
notably:
You can see the journey to Chernobyl in these data because the air pressure in Chernobyl
was a little higher than in Kiev.
You can also see that the three hours in ICE trains (in germany)
at the start were 3°C warmer than at the end, where they were really cool and
i could feel the difference. In the cooler ICE trains i also felt a stronger
air ventilation, but the data logger does not log the wind speed.
Because the data logger was in the carry-on luggage on the flight to Kiev
and in the cargo on the flight back there is no great difference to the first
flight. This is necessary for living cargo.
Trip from Nuremberg to the summit of the Damavand and back in 2010
Temperature, air pressure and air humidity at the damavand
trip, with a short acclimatisation at Alam-Kuh, a pause at the Caspian
Sea, a flight from Tehran to Shiraz and drive back to Tehran.
Due to a snowstorm, a too short acclimatisation and other problems, the
maximum height was only 4900 m.
The reason of the too short acclimatisation is that the
trip organizing company, the austrian
Verkehrsbüro, did not follow the the first two of the
following recommendations for acclimatisation from the
Altitude Tutorial from the International Society for Mountain Medicine:
- At altitudes above 3000 meters (10,000 feet), your sleeping elevation
should not increase more than 300-500 meters (1000-1500 feet)
per night.
- Every 1000 meters (3000 feet) you should spend a second night at the
same elevation.
- You should spend at least one night at an intermediate elevation
below 3000 meters (10,000 feet).
Often the first recommendation can not be implemented, because the
sleeping elevation can not be chosen arbitrary, but by spending
more nights at the same elevation it's always possible to increase
with an average of 300-500 meter per day. And it's always possible
to follow the other two recommendations.
If you don't increase continuing, you have to take into account that
you loose an acclimatisation elevation of 300-500 meter per day if
your sleeping elevation goes down fast (faster than 500 m per day).
So a trip should be checked before booking due to this
recommendations.
But the Altitude Tutorial does not take into account the
Death Zone
which is the zone above 7500 m (some sources say 7000, some 8000
m), where the amount of oxygen cannot sustain human life and where no
human body can acclimatize.
So for very high altitudes other recommendations, e. g. an oxygen
mask, must be used.
The dose rate on the ground was about (0.1 ± 0.015) µSv/h per
kilometer height, like at aconcagua.
The common death rate at Damavand is about 0.02 % and
about 40 % of the tourists make it to the summit.
Outdoor measurement results i found in the web
Comments:
The main source of the activity in the Gasteiner Heilstollen is Radon
with an actitivy of 44 kBq/m3. About 50 % of
the dose is caused by alpha rays, which have a Relative Biological Effectiveness [RBE]
of 20.
At the beach of Lake Karachay the dose is nearly as high as the dose rate at the
burning Chernobyl reactor (1986); you get a deadly dose in one hour!
Therefore Lake Karachay is called the dirtiest place on earth (Lenssen,
"Nuclear Waste: The Problem that Won't Go Away," Worldwatch Institute,
Washington, D.C., 1991: 15).
Some sources say that at the Lake Karachay by the nearby
Kyshtym Disaster
has been released more radioactivity than by the Chernoby disaster, which
released between 5 and 12 Exa-Becquerel (EBq).
An official investigation in 1997 says that the nuclear fuel reprocessing plant
Mayak,
which caused the pollution of Lake Karachay and the Kyshtym Disaster,
released 8,9 Exa-Becquerel (EBq) of Strontium-90 und Caesium-137:
http://de.wikipedia.org/wiki/Kerntechnische_Anlage_Majak#Unf.C3.A4lle_und_Umweltzerst.C3.B6rung.
So the Chernobyl desaster in 1986 was the most famous nuclear accident and the
one with the greatest impact, but the radioactivity from Mayak
has caused nearly the same damage, but more locally, over a longer period
and more hidden by the government.
Ghosttowns like Prypiat can be found at some other places around the
world.
An example is
Hashima Island.
Nuclear accidents on earth are not the worst case of ionizing radiation
on earth: A
Supernova
in a distance of a few hundred light-years or a Gamma-Ray-Burst or jet from a
Hypernova
in a distance of a few million lightyears would expose
the earth to a radiation dose which would destroy the Earth's ozone layer:
http://en.wikipedia.org/wiki/Gamma-ray_burst#Rates_and_impacts_on_life.
And if these novas are much closer, their radiation is deadly for one half of
the earth.
Because the gamma rays do travel with
light speed, these events do come without warning; when you see them, you are
already hit. Because of the light speed, even a warning system with satellites
which do search for gamma ray bursts would not help.
Geiger Counter Links
Sitemap