In Washington State, the Environmental Sciences Section (ESS) of the State Department of Health is responsible for environmental radiation monitoring. They monitor potential radiation release from facilities in Washington State that have radioactive materials. Even if there is no potential for release of radioactive materials into the environment around a facility, monitoring is still conducted in the facility.  Some of the facilities that are monitored are listed below.

            The Dawn Mining Company is a uranium mill located in Ford, Washington northwest of Spokane. It processed uranium from the Midnight mine on the Spokane Indian Reservation. Since the mill was shut down and processing halted, the millsite has proceed with decommissioning which includes demolition of site buildings, contaminated soil removal and contaminated ground water remediation.

            Areva Richland is a company in Richland, Washington that deals with the whole nuclear fuel cycle with emphasis on fuel production. They load fuel rods with radioactive pellets for use in pressurized water reactors and boiling water reactors. They also deal with packaging and transport of spent fuel rods.

            Unitech Services Group is has a facility located in Richland, Washington. They provided radiological laundering services and protective clothing for handling radioactive materials. They also provide other safety gear such as respirators, goggles, boots, gloves, sorbents, soaps, showers, etc. to deal with radioactive materials. They have decontaminate tools and other metals items as well as HEPA air filter units.

            The Puget Sound Navel Shipyard in Bremerton, Washington must deal with nuclear submarines and is included in the Sections monitoring responsibilities.

            The Hanford Nuclear site contains operating nuclear facilities and a great deal of stored solid and liquid nuclear materials. Hanford has been dealt with in other posts on this blog.

            Energy Northwest is a utility company near Richland, Washington which operates commercial nuclear power reactors that feed power into the Washington power grid.

            The Trojan Nuclear Reactor site has been decommissioned but still has some spent nuclear fuel on site which must be monitored.

            The Washington ESS also hosts the Quality Assurance Task Force which works to improve environmental radiation monitoring programs used by various organizations in Washington State. The task force verifies accuracy of monitoring, coordinates sampling, analysis and reporting, improves resource utilization, maintains credibility, disseminates information and encourages public awareness.

            The  Washington ESS operates four environmental radiological monitoring stations as part of the United States EPA nationwide RadNet monitoring system.

            The Washington ESS has been charged with dealing with radon issues in Washington State. Radon is a noble gas that is released from soil and can concentrate in buildings. It is present in concrete, granite, brick and other stone materials used in building and furnishings. It is the number two cause of lung cancer in the United States.

            The Washington ESS protects the public from airborne radioactivity by enforcing federal and state standards for radioactive air emissions. Authority to inspect, review plans and license facilities is delegated by the US EPA and compliance is necessary to insure continued federal funding of many state programs.

 

 

            The United States Environmental Protection Agency (EPA) has a radiation monitoring website called RadNet. From the homepage:

 

            “The nationwide RadNet system monitors the nation’s air, drinking water, precipitation, and pasteurized milk to determine levels of radiation in the environment. RadNet sample analyses and monitoring results provide baseline data on background levels of radiation in the environment and can detect increased radiation from radiological incidents.”

 

            From the RadNet FAQ:

 

            “RadNet is the only nationwide system that continuously monitors of ambient environmental radiation levels and those resulting from major nuclear accidents, such as the Fukushima nuclear reactor incident in Japan. RadNet data are used to inform the public, providing assurance if contamination levels are very low or helping to make science-based decisions about taking protective actions if contamination levels are high enough to warrant them.”

 

            The EPA has thirty locations where they take samples of rain, snow or sleet monthly and forward it to their lab to test it for gamma radiation. The sampling locations have been selected to give comprehensive and representative coverage of precipitation in the U.S. There are also 30 stations where milk samples are being taken quarterly and sent to the lab to be tested for gamma radiation as well as fission products such as iodine-131, barium-140 and cesium-137. Finally, the EPS takes drinking water samples from fifty sites across the U.S. quarterly and tests the samples for fission products.

          The results from these analyses are provided in a database called Envirofacts.  The first search parameter is the location.

   

The location input field will allow selection by state, city & state or EPA region.

 

 

Second, you need to select what you want to see results for which they call Media.

 

The Media field will allow selection of rain, milk, drinking water or air-filter.

 

The next field lets you select a particular radioisotope.

A selection of radioactive isotopes is presented.

 

 

And finally, you can choose which years you want information for.

 

Here is a set of search parameters.

You are given a choice of output units, either traditional units called picocuries or international system units called Becquerels.

          Here is the results of the above search on Envirofacts.

 

Here are the results for Denver, Colorado in a search for Cesium-137 in precipitation.

 

 

            The main purpose of the RadNet monitoring is to establish a base line for normal background radiation across the United States in monitor the air, rain, drinking water and milk for radiation above the safe levels due to nuclear explosions or radiation accidents at reactors.

            The United States Environmental Protection Agency (EPA) has a radiation monitoring website called RadNet. From the homepage:

 

            “The nationwide RadNet system monitors the nation’s air, drinking water, precipitation, and pasteurized milk to determine levels of radiation in the environment. RadNet sample analyses and monitoring results provide baseline data on background levels of radiation in the environment and can detect increased radiation from radiological incidents.”

 

            From the RadNet FAQ:

 

            “RadNet is the only nationwide system that continuously monitors of ambient environmental radiation levels and those resulting from major nuclear accidents, such as the Fukushima nuclear reactor incident in Japan. RadNet data are used to inform the public, providing assurance if contamination levels are very low or helping to make science-based decisions about taking protective actions if contamination levels are high enough to warrant them.”

 

            The EPA has thirty locations where they take samples of rain, snow or sleet monthly and forward it to their lab to test it for gamma radiation. The sampling locations have been selected to give comprehensive and representative coverage of precipitation in the U.S. There are also 30 stations where milk samples are being taken quarterly and sent to the lab to be tested for gamma radiation as well as fission products such as iodine-131, barium-140 and cesium-137. Finally, the EPS takes drinking water samples from fifty sites across the U.S. quarterly and tests the samples for fission products.

          The results from these analyses are provided in a database called Envirofacts.  The first search parameter is the location.

          1

The location input field will allow selection by state, city & state or EPA region.

 

2

 

Second, you need to select what you want to see results for which they call Media.

 

3

The Media field will allow selection of rain, milk, drinking water or air-filter.

4

 

The next field lets you select a particular radioisotope.

5

A selection of radioactive isotopes is presented.

 

6

 

And finally, you can choose which years you want information for.

 

7

Here is a set of search parameters.

8

You are given a choice of output units, either traditional units called picocuries or international system units called Becquerels.

9

          Here is the results of the above search on Envirofacts.

 

10

Here are the results for Denver, Colorado in a search for Cesium-137 in precipitation.

 

11

 

            The main purpose of the RadNet monitoring is to establish a base line for normal background radiation across the United States in monitor the air, rain, drinking water and milk for radiation above the safe levels due to nuclear explosions or radiation accidents at reactors.

            The United States Environmental Protection Agency (EPA) has a radiation monitoring website called RadNet. From the homepage:

 

            “The nationwide RadNet system monitors the nation’s air, drinking water, precipitation, and pasteurized milk to determine levels of radiation in the environment. RadNet sample analyses and monitoring results provide baseline data on background levels of radiation in the environment and can detect increased radiation from radiological incidents.”

 

            From the RadNet FAQ:

 

            “RadNet is the only nationwide system that continuously monitors of ambient environmental radiation levels and those resulting from major nuclear accidents, such as the Fukushima nuclear reactor incident in Japan. RadNet data are used to inform the public, providing assurance if contamination levels are very low or helping to make science-based decisions about taking protective actions if contamination levels are high enough to warrant them.”

 

            The EPA has stationary and mobile air monitors measuring radioactivity 24 hours a day, 7 days a week. Monitoring sites were chosen to give comprehensive coverage to the environment in the United States. These readings are consolidated and rendered as graphs several times a day.

 

            The fixed air monitors pass about 60 cubic meters of air per hour through a filter which is constantly checked for beta and gamma radiation. An average person will breathe about 20 cubic meters of air per days.

 

            There is a map of the air monitoring stations in the US displayed on the website.

 

You can put in your address to find a monitoring station near you. The locator includes a slider that allows you to enter the distance you want the search to encompass.

            The system will zoom into the search zone and show monitoring stations as purple circles. Here is the search results for my zip code in Seattle, Washington.

 

Putting your cursor over the purple spot will show you where the monitor is.

Under the map is a list of states and cities in those states where you can check on the air measurements or the liquid measurements.

            The air measurements show charts of gamma radiation:

 

The radiation measurements are for different ranges of gamma energies. The chart shows the different counts for emission events in these gamma ranges. The diagram below is an example of the total gamma count for a few hours for the ranges shown side by side.

 

 

            The main purpose of the RadNet air monitoring is to establish a base line for normal background radiation across the United States and to monitor the air for significant departures from that normal level caused by detonations of nuclear bombs and incidents at nuclear reactors where radiation is released into the environment. The primary path of such radioactive pollution is through the atmosphere. Initial dangers to the health of U.S. citizens from heightened radioactivity is through inhalation of particles in the air. 

            The menu at the top of the GeigerGraph for Networks includes menus for files, user setup, view, network and help.

 

    

       The FILES menu has options for saving data, clearing data, save the graph, save the whole screen, save all, print graph and print screen.

            The USER SETUP menu has options for editing the identity of your monitoring station, configuring alerts which we covered in the last post, get navy time from the U.S. Naval Observatory, 

 

and other options.

 

 

            The OTHER OPTIONS box includes a check box for showing a Welcome screen on start up, minimizing the program to the Windows system tray, showing a two minute guide on graph appearance, automatic restart of program after computer stops due to power failure, edit monitoring station identity. There is also an input box to set a time for an alarm to indicate detector failure. There are tabs to restore all system defaults and to clear all user entered data.

 

    

   

 

            The VIEW menu has a toggle for switching between a 2-D graph and a 3-D graph. You can call up a spreadsheet of the monitoring data where you can also add comments

 

 

and a report that is formatted for printing.

 

 

 

You can go to the GeigerCounters.com website, the radiation map with all the monitor stations. You can display or hide a set of remote monitoring stations as small boxes on the screen.

 

 

 

            The NETWORK menu lets you work with pager alerts and email alerts, You can join the Radiation Network and set up your system to run a web program. All these choices are covered in the previous post.

 

 

            The HELP menu includes choice to a ‘help narrative’ that walks you through how to use the program, troubleshoot the network by checking various system settings, open info files which are text files that contain information on the network parameters and the radiation network statuses, read the license agreement and a version screen for the GeigerGraph software including websites for contact.

 

 

            There is a cluster of icons on a tool bar that toggle 2-D and 3-D, save an image, save all data, show the spreadsheet, show the report, test alert sound, check naval observatory time,  print graph, go to GeigerCounters.com website, and call up help. 

 

 

             There is a second cluster of icons that bring up the pager alert screen, the email alert screen, view radiation map and view remote monitoring stations.

 

            GeigerGraph for Networks is a simple software package that allows you to monitor local radiation and upload it real time to a national map of monitors. The operation is easy and it is inexpensive. If you are concerned about radiation levels locally and nationally, then buy a compatible Geiger counter and the software and join the Radiation Network.

           

            GeigerGraph for Networks is a program created by a company called Mineralab. It is distributed through a subsidiary called GeigerCounters.com. GeigerGraph is used to create a network of automatic monitoring stations on a volunteer basis for reading and uploading counts per minutes Geiger counter readings. The main focus is on the continental United States but there are additional monitoring maps for Alaska and Hawaii, Europe, Japan and Australia. Anyone who wants to can purchase a compatible Geiger counter, purchase the software, connect to the network, register their station and begin uploading data. There is a demo that will allow you to check out the software before you purchase. GeigerGraph for Networks is available at http://www.geigercounters.com/NetworkVersion.htm%20.

            Using a data cable, connect a compatible Geiger counter to a serial port on your PC computer with Window 98 or later operating system. Download the software and install it on your computer. The first thing that you will have to do is to sign up for the monitoring site, www.radiationnetwork.com.

            There are fields to enter your name, country, city, state, latitude, longitude, altitude, a name you chose for your station, a personal password, model of Geiger counter, and other notes you want to add.

               The main screen shows the counts per minute of radiation detection on the vertical axis and the time of the readings on the horizontal axis. It reads second to second for a minute and displays the data points on the graph. There is a display above the graph that gives additional information about your readings:

            There is also a menu to set alert levels above the chart:

First you can set the level in counts per minute. Then you can have a line displayed on the graph which will show the alert level. If you enable the Alert Pop Up, a red box will appear on the screen when the alert level is exceeded.

            The Advanced tab on the Alert menu has addition parameter setting for handling alerts:

            You can trigger a program on your computer to execute when an alert is generated.

Set the alert level and either type in the path and name of a program to execute or browse your system to select the program. When the CPM level accedes the threshold you set.

            Another tab on the Advanced screen allows you to set up your system to trigger an external device through a relay connected to a serial port:

            There is a tab that will let you test the alert sound generated by your system when the threshold is exceeded.

            Finally, there is a tab that lets you configure how you want alerts generated by your system to be relayed to the rest of the network.

The Paging Dialing tab takes you to a screen where you can enter a whole set of people to be page if there is an alert.

The E-Mail Notification tab takes you to a screen where you can set up email parameters and a list of people to email if there is an alert on your system.

The Join Radiation Network tab will allow you to download readings from other stations to your map.

Finally, the Web Program tab will let you set up a program on a web server that will trigger whenever there is an alert or trigger each time the CPM level is updated from you system.

            Continuing concern over radiation exposure sparked by the Fukushima disaster has led to a number of programs to monitor radiation across the United States. One of these programs is called the Radiation Network at www.radiationnetwork.com. The home page displays a map of the continental United States.

            Little radiation symbols on the map show the location of nuclear installations. There are colored circles on the map which indicate a location where someone is monitoring radiation The orange circles show local stations, the yellow circles indicate remote monitoring stations. There are white disks for simulated monitoring stations and yellow circles with triangles on top to indicate mobile monitoring stations. A red circle will show where there has been a radiation alert issued.

            The number in the colored circles indicates the counts per minute (CPM) registered on Geiger counter at the monitoring station. Measuring radiation is complicated but for the moment 120 CPM would be equivalent to about 1 microsievert. (μSv). The alert level for the map is over 100 CPM or about .84 μSv. There is a date and time stamp at the bottom of the map which gives the date and time in Arizona when the map was last updated. The usual update rate is every few minutes.

            Email to the Radiation Network site is answered on the Messages page which will also have messages about alerts. There is also an additional page that shows monitoring stations in Alaska and Hawaii. There are additional pages for Europe, South America and Japan. These maps outside the United States only have a few monitoring stations.

            If you want to join the site and begin uploading monitoring data, first you need to purchase one of the compatible Geiger counters. Currently this is the list of counters: The Geiger, Monitor 4 (yr 2008 redesign), Radalert, Radalert 50, Radalert 100, Digilert 50, Digilert 100, palmRAD, CRM-100, Inspector, Inspector EXP, Images SI models, PRM-8000. Many of these are available at www.GeigerCounters.com. Other counters that have pulse output through a data or audio port may be compatible. Second, you need the GeigerGraph software and a data cable, also available from www.geigercounters.com/NetworkVersion.htm. Third, a computer with these minimum system requirements:  Windows operating system, Pentium processor, CD-ROM drive, serial port or USB port with serial adapter, additional ports for GPS use, 1 GB RAM, 75 MB of hard disk space, 16-bit or higher color, and Internet Explorer 4 or higher. Fourth, you need access to the Internet. Go to the website www.geigercounters.com/NetworkVersion.htm and register your monitoring station.

            If you choose to participate in this radiation monitoring network, it will tie up your Geiger counter which will, in essence, become a dedicated monitoring device connected directly to the network and uploading local radiation level information from moment to moment.

Radiation Network Map:

 

            Let us start from the assumption that you now have a hand-held Geiger counter and you want to make readings. Here are some tips:

Background Level

            See previous post about background levels of natural radiation. You can use the numbers from that post but it would be better to go online and see if you can find background radiation measurements from your state, county, municipality or a university in your area. A little research should turn up a good background number for where you live.

Atmospheric Measurements

            Measuring radioactivity in the air will depend on atmospheric conditions. There will be detailed online weather information for just about anywhere in the United States that is near a town or city. Learn about prevailing wind directions and speeds where you live. Also track humidity levels and air pressure. If you are doing readings of atmospheric radiation and detect levels substantially above normal background levels, be sure to note wind direction, speed, humidity and barometric pressure that are associated with that particular reading.

Measuring objects

            We live in an interconnected global world. Goods are being shipped around constantly. You may be receiving parcels from anywhere or purchasing items from any continent. If you are testing items that you have ordered or purchased, hold the detector as close as possible to the object and then move it around because radioactive emissions may be asymmetrical and you may get a different reading from different orientations.

Measuring food

            In a study of what are called food miles, it has been found that some of the items on the average dinner plate in the United States have traveled over 1500 miles. In some cases, food has traveled much further than that. Fish pulled out of the ocean off the coast of California may have come all the way across the Pacific from Japan. Radioactivity in food tends to accumulate as it is grown or grows. Then it can accumulate in your body over time as you eat more of something. Since there is a growing debate as to whether there is any “safe level” of radiation even low levels in food might be a health issue. Handheld Geiger counters are not sensitive enough to pick up very low levels of contamination but will detect serious levels of contamination that will mean the food is not safe to eat.

            If you are going to test food and you live in a brick, stone or concrete building it would be best to go outside to do the testing. Best to test on a wooden table because stone, tile, concrete or brick surfaces have higher background levels. Best time to test is when the background radiation is lowest which is just before local sunrise. Get as close to the sample as you can but don’t touch it because you might contaminate the Geiger counter. Use at least a pound of solid food or a quart of liquid for the test. The longer you test, the more accurate your results will be.

Logging your tests

            Keep a log book for your tests with columns for things like time, date, place, item, reading,  As you accumulate data, you will be able to analyze readings over time to see if patterns emerge.

In order to accurately measure radiation with a Geiger counter, we must start with the normal background radiation. Background radiation comes from both natural and man-made radioactivity. Previous posts have detailed various sources from both of these types. The actual regular background radiation varies from place to place on the surface of the Earth. It also varies with time depending on the weather, the seasons and human activities. In addition, different information sources give different standard background radiations for the same place.

            Here is a chart from a Wikipedia article.

           This next chart is from the US Nuclear Regulator Commission.

           Converting from millirems to millisieverts at 100 to 1 yields natural sources contributing 3.1 mSv and Manmade sources contributing 3.1 mSv for a total of 6.2 mSv per year.  S you can see, the quoted levels for the US vary from 2.0 mSv to 6.2 mSv.

           To understand how much radiation you are exposed to in the course of a year, you must take into account more than just the background radiation where you live. You also have to include events and activities in your life.

            If you smoke, it will add 2.8 mSv to your annual dose. Bear in mind that second hand smoke from being around people who smoke will also add to your annual dose. People who frequent or work in establishments which permit smoking may be getting a lot more than 2.8 mSv per year.

            Altitude changes your dose because higher up, you have less atmosphere and more exposure to radiation caused by cosmic rays. Here is a table of mSv for altitudes above sea level measured in feet.

 

Altitude Chart.PNG

            The region of the US where you live influences your exposure. to radiation. The Gulf coast exposure is .23 mSv, the Atlantic Coast exposure is .23mSv, the Colorado Plateau exposure is .90 mSv and in the rest of the US, the exposure averages .46 mSv.

            Of the radiation you carry in your body, .40 mSv comes from food and water, 2 mSv comes from Radon in the air, plutonium powered pacemakers contribute 1 mSv, and porcelain crowns in your teeth add .0007 mSv.

            Travel can also contribute to your annual radiation dosage. Airplane travel contributes .01 mSv per 1000 miles traveled. Airport security scanners add

            If you live in a stone, brick or concrete building you will get .07 mSv from your residence.  Television adds .01 mSv per year and computers add .001 mSv. Medical X-rays are .4 mSv each. Nuclear medical procedures are .14 mSv each. Living within 50 miles of a nuclear power plant will give you .00009 mSv per year and living within 50 miles of a coal fired power plant will give you .0003 mSv per year.

            The above numbers come from a brochure published  by the American Nuclear Society. As you can see, many factors contribute to the amount of radiation you may be exposed to in the course of a normal year.

            The exposure range here of 2 mSv to 6.2 mSv translates to .23 μSv/per hour to .71 μSv/per hour, the type of readings that are typical for a Geiger counter.

           

 

            There are many manufacturers who market many different models of Geiger Counters. Websites have been created that bring together selections of different models with comparisons of features.

            Alibaba.com is a directory site that brings together Geiger counters from manufactures all over the world. Each listing shows a model, a link to a page dedicated to the manufacturer and contact information for each manufacturer. It is a very comprehensive site with details on the models from each manufacturer but does not offer comparisons. Some of the models shown can only be purchased in quantity.

            Geigercounters.com is an excellent site for comparing Geiger counters. They have short tutorial pages on radiation, danger levels, applications, food contamination, Geiger counter basics and Geiger counter types. Their site offers a section on portable inexpensive Geiger counters and another section on more expensive probe style Geiger counters.

            There are two main types of Geiger-Müeller tubes used in these Geiger counters. The most common is the long cylindrical type which we have covered in another post. The second type of probe is called a pancake. This type of tube is a flattened cylinder sort of like a hockey puck. The anode inside the cylinder consists of concentric circular wires parallel to the face of the detector. Like the long cylinder style tubes, the pancake type will have either a mica or metal cover on one end to allow entrance of radiation. This type is used primarily to detect gamma radiation but they can also detect alpha and beta. With a much larger entrance window than the long tubes, the pancake tubes are more sensitive.

            The Geigercounters.com selection of handheld counters includes nine models that are priced from $289 to $569. They are compared in a big chart with about fourty different features as well as size and weight. They vary in size from 6.6″ X 3.3″ X 1.3″ to 8.1″ X 2.8″ X 1.9″. Their weights range from 7.3 ounces to 12.5 ounces. The battery life of different units measuring normal background levels of radiation ranges from 50 hours to 28,000 hours. They are all powered by regular 9 Volt batteries. The counters use either analog meters or digital displays. They have a range of sensitivities. Most have data ports and a software option. All but one have long cylindrical Geiger-Müeller tubes. The exception has a pancake style Geiger-Müeller tube which has an entrance window about five times bigger than the long cylinder types. All of the units covered are manufactured in the USA.

            The Geigercounters.com selection of probe counters includes four models that are priced from $279 to $1,075. They are compared in a big chart with about fourty different features as well as size and weight. They vary in size from 6″ X 3.2″ X 1.2″ to 9″ X 4″ X 5″ Their weights range from .8 pounds to 4.2 pounds. These units take standard alkaline batteries. The battery life of one of the units is around 2000 hours measuring normal background levels of radiation. One has a long cylindrical Geiger-Müeller tube and the rest have pancake tubes. One of the counters in this set has Bluetooth wireless data transfer. The counters use analog meters, digital or just flashing LED displays.

            Whether or not you choose one of the models for sale on the Geigercounters.com website, checking out the features on the comparison chart will definitely prepare you to evaluate the specification of any other Geiger counter you might be considering.

Pancake Geiger-Müeller tube:

            There are many manufacturers who market many different models of Geiger Counters. Websites have been created that bring together selections of different models with comparisons of features.

            Alibaba.com is a directory site that brings together Geiger counters from manufactures all over the world. Each listing shows a model, a link to a page dedicated to the manufacturer and contact information for each manufacturer. It is a very comprehensive site with details on the models from each manufacturer but does not offer comparisons. Some of the models shown can only be purchased in quantity.

            Geigercounters.com is an excellent site for comparing Geiger counters. They have short tutorial pages on radiation, danger levels, applications, food contamination, Geiger counter basics and Geiger counter types. Their site offers a section on portable inexpensive Geiger counters and another section on more expensive probe style Geiger counters.

            There are two main types of Geiger-Müeller tubes used in these Geiger counters. The most common is the long cylindrical type which we have covered in another post. The second type of probe is called a pancake. This type of tube is a flattened cylinder sort of like a hockey puck. The anode inside the cylinder consists of concentric circular wires parallel to the face of the detector. Like the long cylinder style tubes, the pancake type will have either a mica or metal cover on one end to allow entrance of radiation. This type is used primarily to detect gamma radiation but they can also detect alpha and beta. With a much larger entrance window than the long tubes, the pancake tubes are more sensitive.

            The Geigercounters.com selection of handheld counters includes nine models that are priced from $289 to $569. They are compared in a big chart with about fourty different features as well as size and weight. They vary in size from 6.6″ X 3.3″ X 1.3″ to 8.1″ X 2.8″ X 1.9″. Their weights range from 7.3 ounces to 12.5 ounces. The battery life of different units measuring normal background levels of radiation ranges from 50 hours to 28,000 hours. They are all powered by regular 9 Volt batteries. The counters use either analog meters or digital displays. They have a range of sensitivities. Most have data ports and a software option. All but one have long cylindrical Geiger-Müeller tubes. The exception has a pancake style Geiger-Müeller tube which has an entrance window about five times bigger than the long cylinder types. All of the units covered are manufactured in the USA.

            The Geigercounters.com selection of probe counters includes four models that are priced from $279 to $1,075. They are compared in a big chart with about fourty different features as well as size and weight. They vary in size from 6″ X 3.2″ X 1.2″ to 9″ X 4″ X 5″ Their weights range from .8 pounds to 4.2 pounds. These units take standard alkaline batteries. The battery life of one of the units is around 2000 hours measuring normal background levels of radiation. One has a long cylindrical Geiger-Müeller tube and the rest have pancake tubes. One of the counters in this set has Bluetooth wireless data transfer. The counters use analog meters, digital or just flashing LED displays.

            Whether or not you choose one of the models for sale on the Geigercounters.com website, checking out the features on the comparison chart will definitely prepare you to evaluate the specification of any other Geiger counter you might be considering.

Pancake Geiger-Müeller tube: