Geiger counter is quite easy to handle and only needs related technical knowledge about the type, nature, energy level of radiation, and how to safely measure the specific type of radiation coming from a radioactive source.
To accurately measure radiation, you need to know how to read the Geiger counter for any radiation type.
How to Use the Geiger Counter?
If there are ionizing radiations coming from subjected material or in the environment, then the electric circuit of the Geiger tube can detect them using its tube and electric circuit.
Geiger counter has blinking light whose blinking speed changes as it detects radiations, it is also supported with a beeping sound.
To take a reading using the Geiger counter simply turn on the counter in order to apply a high voltage across both electrodes of the tube. Hold it still for a while to measure background radiation and then use it to measure radiation coming from radioactive material.
The sensitivity of the counter largely depends on the size of the tube. The larger the tube is the higher sensitivity the Geiger counter will have.
Geiger counter can measure ionizing radiations in many different units, like in counts per minute (CPM), micro Sieverts per hour (µS/h) or in micro roentgen per hour (µR/h).
Be sure of the unit reading displayed on the counter display and the unit you are considering for the chart reference. It means if your Geiger counter shows the unit of counts per min (CPM) and any reference chart or table you have has the unit of counts per second (CPS), be careful. Be sure of making proper unit conversion before making any decision.
How to Read the Geiger Counter Reading?
Geiger counter normally presents ionizing radiations in counts per minute (CPM) or counts per second (CPS). When ionizing radiations ionize the gas present in the tube, then these ions move toward the electrodes and make ion pair there.
Whenever an ion pair is made, a beep sound can be heard, and that counts one. Count the number of beeps for any fixed interval of time and then divide the beep count with time to get counts per minute. Fortunately, most counters have a built-in count per minute digital display setup to count and show the CPM or CPS value.
Due to background radiations, the Geiger counter starts to make a beeping sound as soon as it’s switched on. An average natural background radiation count can be between five to sixty counts per minute. So, don’t get confused if your Geiger counter gives an output while you are not measuring anything.
Precaution When Reading Geiger counter
1. Type of Ionizing Radiation
Geiger counters cannot differentiate between types of ionizing radiations or they cannot work to provide the level of energy of ionizing radiations. It’s up to the user to do the necessary work for the detection of any particular radiation type.
2. Medium of Travel of Ionizing Radiation
The medium in which the radiation travels to the Geiger counter’s tube can affect the exposure as well. For example, Alpha particles can travel through air but even a piece of paper can block them.
Similarly, Beta particles cannot pass through plastic sheets but gamma particles can easily pass through any material. So a proper consideration of the medium between source and tube should be made before comparison and multiple readings.
3. Distance Between Source and Tube
Distance between the ionizing radiation source and the tube of the Geiger counter is very important. So keep the distance the same when taking multiple readings of ionizing radiations of the same or multiple sources.
4. Geiger Counter Specifications
All Geiger tubes are not the same; each counter is designed to detect a specific range or type of ionizing radiation. So be careful while selecting or using a Geiger counter for a specific task.
Geiger Counter Chart
Just reading your Geiger counter is not enough to protect yourself from ionizing radiation. One needs to have complete knowledge of different levels of ionizing radiation and knowledge of which level is safe or normal and which level of ionizing radiation should be avoided.
The addition of this different unit of ionizing radiation also makes it a little confusing for the user to understand the Geiger counter reading.
Let me break down the reading:
- Normal background reading of 5 to 50 CPM is usually generated by natural resources and they are around us almost every time. This level of ionizing radiation is considered safe for every time of life on earth.
- Anything above the range of 50 CPM cannot be considered normal and from 51 to 99 CPM of radiation is considered medium-level exposure. This level of ionizing radiation cannot cause any serious damage instantly but precautions are recommended.
- Reading above 100 is extremely dangerous. Three basic precautions of minimizing time, increasing distance, and use of protective equipment are recommended till the reading is below 100 and the source of the high level of ionizing radiation is identified and eliminated.
- Reading above 1000 CPM is something normal people should not encounter in their life. If anything like this case to you, take immediate action to leave the area then inform the government for necessary action.
Other related pages:
- Best Geiger Counter Reviews
- How Geiger Counter Works
- How to Calibrate the Geiger Counter with A Known Radiation Source
- How to Read & Use Geiger Counter
- How Accurate is Geiger Counter to Measure Ionizing Radiation?
- What is the Safe Level of Ionizing Radiation for Humans?
- Best Dosimeter Reviews
- List of Instruments to Measure Ionizing Radiation