1)     What is the radiation?

Radiation is the emission of energy from any source. When talking about radiation and cancer, we are talking about x-rays, natural background radiation from the earth and sky and the radiation made by nuclear reactors (Gamma rays).

2)     What is the average background radiation in USA?

Radiation is a part of the natural environment. This background radiation is contributed principally by three sources: terrestrial radiation, cosmic radiation, and radiation from radioactive elements in our bodies. The average background radiation in the United States is approximately 3000 μSv/year, or 0.34 μSv/h.

3)     What is Geiger counter?

The Geiger-Muller is a type of particle detector that measures ionizing radiation. It detects the emission of nuclear radiation: alpha particles, beta particles or gamma rays by the ionization produced in a low-pressure gas in a Geiger–Müller tube, which gives its name to the instrument.

Invented in 1908, Geiger counters remain popular instruments used for measurements in dosimetry, health physics, experimental physics, the nuclear industry, geological exploration and many other fields, and is probably the best-known nuclear instrument to society due to its wide and highly visible use as a hand held radiation survey instrument.

4)     Is Pocket Geiger a real Geiger counter?

Pocket Geiger is not a traditional Geiger Muller counter which has a pressurized gas tube. It is a silicon semiconductor detector. It consists of a silicon crystal which is doped with impurities to make p- and n-type silicon. A p-n junction, a small region called the depletion zone, is created between p- and n-type silicon because of initial diffusion of electrons and holes. When the detector is irradiated electron-hole pairs are produced within the depletion zone and gives rise to a radiation-induced current.

5)     What are the uses for Geiger counter?

Hobbyists and individuals use our detectors to test rock samples, to check ambient radiation levels, for gross detection of radon in the home, to learn about radiation and for personal monitoring of cumulative radiation doses.

6)     Can Pocket Geiger detect alpha, beta and gamma radiation?

Due to the shielding, Pocket Geiger can detect X or Gamma Ray radiation only.

7)     Can Pocket Geiger detect Radon gas in the house?

The Pocket Geiger detector can be used to indirectly detect radon gas (it’s an alpha emitter). One would do so by concentrating the radon for a few days (1-3) using activated charcoal and measuring the charcoal for any radiation readings. Note this only measures the presence of radon, for accurate pCi/L measurements one can purchase a radon gas detector.

8)     Can Pocket Geiger detect radiation in food or water?

The Pocket Geiger detector is a general purpose survey meter, the typical use for the device is to measure ambient radiation levels, monitor personal dose rates, and determine sources of radiation leakages or identifying rock and metallic samples as radioactive. The detector is not able to detect low radioactivity in food or water unless they are really contaminated by the radiation.

Again, the most comprehensive radiation detection and measurements on food and water are done by labs and government institutions using scintillation detectors and complex methods to concentrate the radioisotopes and to shield the testing from background radiation noise. Scintillation detectors costs tens of thousands of dollars, but are orders of magnitude more sensitive than Pocket Geiger counters.

9)     Can Pocket Geiger detect radiation in the soil?

Yes, you can measure radioactive pollution for soils.  To do this, keep the sample in an airtight container and put Pocket Geiger on it with its sensor-side facing down. The sensor-side has a ring-shaped circle.

10)  How Pocket Geiger is calibrated?

At the design stage, the Pocket Geiger detector was calibrated and tested using a standard Cs-137 source and certified by Netherlands National weighing station (Dutch Metrology Institute No.3320408).  Then sampling Pocket Geiger detectors were tested near Fukushima Daiichi nuclear power. Although individual detector is not calibrated, it is inspected before shipping to customer that the variation in performance among individuals within a certain range.

11)  What is the difference among Type 4 and 6 Pocket Geiger?

Pocket Geiger Type 4 is for iOS device. Type 6 is for Android and Window PC device.

12)  Can I take a Pocket Geiger on a plane?

Yes, it is safe to carry a Pocket Geiger on an airplane. It will not emit radio interference. The x-ray machine will not damage the Pocket Geiger. Furthermore, the Pocket Geiger contains no radioactive material and emits no ionizing radiation. People have taken our detectors on planes to see for themselves that the radiation on a flight in the air is markedly more (3 – 5 times) than background radiation on the ground.

13)  Where is the Pocket Geiger made?

The Pocket Geiger is designed and manufactured in Japan

14)  What is the Pocket Geiger performance?

Performance of the detector is composed of two parts: sensitivity and accuracy.

In the low-dose region (<0.1 μSv/h), it takes approximately 10-15 minutes to get a stabilized reading.   If dose is high than 0.1 μSv/h, the recommended measuring time is about 5 minutes. Pocket Geiger requires longer time to get reliable readings compared with Scintillation or Geiger Muller based detectors. For “accuracy” check, please read user’s feedback at www.Radiation-Watch.org.

15)  I got a reading in my house of .81 cpm, .05 +-0.01 µSv/h with a 1.97 RMS%. What does that translate into the .34 µSv/h that an average individual background radiation dose would be?  What does cpm and the RMS% mean?

Radiation sensors detect radiation particles which is random-distributed in an environment. So there is statistical uncertainty (counting errors) to measure radiation level. The error will be reduced depending on the measurement time. In the Pocket Geiger App, statistical error range (1 sigma) is always displayed after +- sign to show exact information of the counting errors. In general, the longer the time it takes to measure, the smaller the error will be.

RMS = SQRT( Sigma{ ( audio_input_signal_level[%])^2 } ) [%], for every last 200 msec We use % unit because the audio input function returns 0 to 100% values for audio input level. 100% is a maximum level of audio input in the device. Usually, RMS is almost constant regardless of radiation level because radiation pulse is too narrow so it will be flatten. If you use Type2, RMS will be around 2%, but please note that the reading changes depending on iOS devices model because each iOS models have different input gains. If you use Type3 or Type4, RMS should be quite low (<0.1%) because the background noise will be eliminated by the internal circuit (comparator). RMS% is a useful indicator for us to diagnose users’ problems.

There is a relationship between cpm (counter per minute) and µSv/hr. it was calibrated using Cs137 source. Detailed information can be found on www. radiation-watch.org

0.34uSv/hr is an average background radiation in USA. The actual reading for different parts of the country will be different.

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