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 MS-Windows software not: With the GammaTool, which does not run under MS-Windows 8, 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 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.
Under MS-Widows 8 you can use the Gamma Scout Toolbox, but installing the drivers ist not easy ant the Gamma Scout Toolbox can't plot the data.
Under Linux there are two alternatives in Python: A script for reading the raw data and a script for plotting the data into a PDF file, under https://wiki.internet-village.be/display/safecast/Gamma-Scout. To get them working it's necessary to add some lines, e. g. to break the endless loop in the first script.
The second alternative is the Gamma Scout Utility for reading and conversion of the data, setting the date/time, clearing the memory etc.: http://johannes-bauer.com/linux/gammascout/. There are also the Gamma Scout Tools at http://www.teodori.org/software-development/gamma-scout-tools-on-opensuse-12-3.html but they are made only for OpenSuSE and even after conversion with Alien to a DEB package (and installation) they do not run under Ubuntu.
The data capacity of the Gammascout is 2 years with 1 day log interval, 4 weeks with 1 hour interval, 4 days with 10 min. interval and 10 hours with 1 min. interval.
The battery is a AA size Li battery (14,65 x 50,3 mm, 2.6 Ah) with soldering tags.
The data sheet of the geiger tube LND 712, aka ZP1401, 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 at june 2011 around 88 Euro, but 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.
|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 about 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||
If not commented with about, the value is an average of minimum two 24 hour averages, measured 2006 or later.
From a Cammenga Tritium Kompass i took a small luminescent piece on the window of the tube and could measure the beta radiation of the tritium. So even the soft beta ray from Tritium can be detected with the Gamma-Scout.
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:
and in the cosmic ray variations sites chapter at
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.
|Machame route profile|
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:
Temperature, air pressure, air humidity and accelerations at the trip.
Doubling the sensitivity with a bigger tube, 2013-06
After six years i changed the battery and the tube to get a doubled sensitivity
and therefore clearer results. Depending on the calibration of the original tube
the sensitivity is not exactly doubled but that can be taken into accout by
measuring an old known activity and back-calculation.
The old battery has a voltag of 3.66 V and a short-circuit current of 120 mA, which indicates about 50 % capacity.
This LND 72314 did cost me about 190 Euro and has twice the sensitivity of the old tube (ZP 1401). An additional advantage is that the LND 72314 background is only 1.8 times higher than the background of the old tube, so that the signal/background ratio is better.
After the modification the Gammasout is glued together with transparent tape and now therefore lesss robust and about 1 cm thicker, but that's no problem because it still fits into a pelicase 1040 (after removing the black rubber at the bottom).
To get the new tube into the case i removed the ray selection. With a sheet of paper, a small and a big pack of paper (or a smartphone) you have the same function.
Another modification was shorting one of the 4.7 MOhm resistors from the HV supply to the tube, because the new tube needs a lower resistance to the HV supply. At medium high doses of 150 µSv/h i could see the current pulses of the HV supply in the display by a lower contrast, caused by the temporary reduced supply voltage. So i added a 6800 µF / 35 V capacitor at the battery to stabilise the supply voltage.
|Dose rate at the Gasteiner Heilstollen 2009, source http://www.gasteiner-heilstollen.com/tl_files/pdf-dateien/Wissenschaftliche%20Informationen%20Radon-Therapie%20LOW.pdf :||
|Dose rate at the beach of Lake Karachay 2007, source http://en.wikipedia.org/wiki/Lake_Karachay#Current_status :||
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 the japan Hashima Island. A more modern version, with real radioactive contamination, is the 2011 made Fukushima alienation zone, but it will be opened for tourists in several years, around 2020 or later.
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