GammaGuard

The Always-On Radiation Detection Application for Android

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Detecting Smoke Detector Radiation and Calibrating the App

This tutorial shows how to use a smoke detector to calibrate the GammaGuard app on your phone and find the conversion factor to convert Counts to uSv units.
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An ordinary smoke detector.
description here Find the position of the source on the smoke detector : Usually the Am-241 source is located in a metal (aluminum) case inside the smoke detector
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When you find the metal case, mark the rough position of the center of the case on top of the detector case.
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This spot is the rough location of the source. now face the camera to this marked point before start measuring, make sure that the data Logging is enabled and the app is calibrated (by pressing the calibrate button). to enable the data logging, go to settings, enable the data logging and save settings
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Let the app run for a certain amount of time, i.e one hour, and then read the total dose value either on screen or from the logged data. divide this total dose by the total time that has passed (1 hour) to get an estimation of the dose rate
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Data are logged out to the phone memory [find the csv file in "your phone memory/GammaGuard complete/dataLog-camera.csv"] every 5 minutes by default (you can change this time in command line ) . Divide the total dose by the total time that has passed to calculate the dose rate.
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Radiation level from smoke detectors are expected to be around 1 uSv/h. So after finding out the reading values from the app (1.405 uSv/h in our example), compare it to the expected 1 uSv/h and insert the conversion factor ( ~ 0.7 in our example) into the command line in the settings. for inserting the conversion factor, go to the settings and enter the small letter "f" following by the factor you calculated before ("f0.7" in our example). Then press the "save settings" button. A message will be displayed to confirm your change then press "OK". Now your measurements are more accurate on any reading units.
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This graph shows that the GammaGuard app, installed on Samsung Galaxy Note 2 phone, can distinguish the small radiation field (1 uSv/h) coming out of a smoke detector and the Background Radiation. we also have done the smoke detector tests on different phones on different configurations of the app. please click here to see the results.



Environmental Instruments Canada, Inc