Of the counter and plug the other end of the

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of the counter, and plug the other end of the connecting cord into the LabPro Interface port labeled “DIG/SONIC 1”. The computer uses the software LoggerPro in conjunction with the Geiger Counter to measure radiation. For a description of the LoggerPro software see Appendix E . To begin measuring radiation amounts the power switch on the Geiger Counter must be moved to the “ON” position, or the “AUDIO” position. The Geiger Counter’s red light will flash whenever it makes a radiation count. When in the “AUDIO” position the counter will also make a beep noise whenever it makes a radiation count. There is a switch on the Geiger Counter that controls its detection sensitivity. The switch has positions labeled 1X, 10X, etc. For the lab problems in this manual the 1X position will most likely be the best setting. Counts recorded by the detector are the result of radioactive decay, which is a randomly occurring event. Events that are the result of random processes have inherent uncertainty. This means that if the count rate for a certain sample is recorded several times, the number of counts recorded will fluctuate around an average. In a set of N counts, if N is small the uncertainty in N will follow Poisson Statistics. If N is large the uncertainty will follow Gaussian Statistics. (These terms are explained in any math reference book, for example see http://mathworld.wri.com). Keep uncertainty in mind when deciding how many counts are "enough" to allow comparisons among count rates under different conditions. 218
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