![]() ![]() The risks associated with radiations is in fact divided into those from internal radiation, that results from radioactive particles becoming absorbed or into a person’s body, and those from external radiations from people being next to the source of radiations.ĭealing with the external radiations, if the amount of Radium used to create fluorescent dials is small, the radiation should not be so intense. The danger is actually less in radiation than in the ingestion of the contaminated dust that accumulates behind the instrument’s glass as the intensity decreases with the square of the distance from the source. The radiation can be sufficiently penetrating to break chemical bonds which are essential to the structure and function of living tissue possibly causing (depending on the intensity and duration of the exposure) serious health problems. This means th at a 70 years old instrument is still well active and will be for the next thousands years. Its most stable isotope, Ra-226, has a half-life of 1602 years and decays into radon gas. ![]() The Radium is one of the most radioactive chemical elements (symbol Ra and atomic number 88), 1000 times more radioactive than Uranium. With the same procedure, but without removing any glass, the Geiger counter found gamma radiation being emitted by another instrumment.įollowing the discovery of radiactivity in normal flight instruments we started an extensive search on the Internet and found that most instruments made up until 1960s had the luminous paint, needed to read them at night, based on Radium. Since he previously hadn’t detected anything (when the instrument was closed) he was sure that alpha particles were causing that large amout of “clicks”, since alpha particles may be completely stopped by a sheet of paper (in his case, by the glass of the instruments), beta particles by aluminum shielding while gamma rays can’t be stopped and can penetrate deeply unless stopped by a thick layer of lead. ![]() My friend opened the instrument in order to clean it and when he used the counter again to detect radiation, to his surprise, he heard multiple frequent clicks, meaning that the portable device was next to “something” emitting either radioactive particles or rays. The tube amplifies this conduction and outputs a current pulse, which is heard as a “click” if you hear a click every now and then, you should not worry but if clicks become frequent it means you are near a radioactive source). He neared the counter to the glass of the instrument and got no audible tone ( the Geiger counter has a gas-filled tube that conducts electricity when a particle or photon of radiation makes the gas conductive. His Geiger counter is able to detect alpha and bravo particles, and gamma rays. This friend has also a small Geiger counter that he uses to inspect all the items he receives from abroad because he was taught nuclear physics at school. Here’s the reason why.Ī friend of mine, who’s keen on aviation, recently bought on eBay an old ADI (Attitude Indicator). ![]() However, former pilots and current airliners crew and frequent flyers could find something interesting in this article. This post is addressed to the many visitors of this site who repair, restore or simply collect old instruments like altimeters, turn and slip indicator, compasses, etc. ![]()
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