1-9. TESTER EVALUATION USING MANUAL STANDARD COUNT

TM 5-6635-386-12&P NOTE Place the source rod in SAFE position and be sure the tester is at least five feet from nearby objects. Stand the shipping case on end and place the reference standard across the protective strips on the case Three buttons on the reference standard fit into accommodating depressions in the bottom of the tester. See Fig. 1-2. At this point two counting methods may be used: Manual, with successive counts. Automatic, with four minute averaging. The Manual method is used for periodic tester evaluation per Para 1-9. The Automatic method is used for routine daily standard count accumulation into the tester Standard Count Memories. Manual method Successively accumulate 10 1/4 minute counts. Do NOT use other time periods for purposes of evaluating tester performance under this program. Proceed to Para 1-9. Automatic method Press STD and LOCK simultaneously on the keyboard and the tester will now clear all four memories, and will count a 4 minute count into all four memories. The 4 minute count will be normalized to a 1/4 minute common base for ease of subsequent computations. Record the final average of either method on the daily field work sheet. The 4 minute automatic standard count will be retained in memory until erased by the next STD or by the taking of a TEST count. 1-9. TESTER EVALUATION USING MANUAL STANDARD COUNT Periodically, the tester should be checked for good statistical operation. This is the ONLY way the operator can verify that his tester is operating correctly. Using this technique, it is possible to predict a future failure before it is severe enough to cause field errors or complete breakdown. This periodic evaluation should be performed at least once a month or whenever the tester has not been used for several months. All nuclear method testers will vary in count rate from one undisturbed count to another due to the random nature of the radioactive source decay. This is a very reliable random rate in that it faithfully obeys the laws of statistics relative to random sources of "population’...where population = count rate for nuclear testers. Given: Any series of numbers taken among a varying population of events will exhibit a form of standard deviation. A series of nuclear tester counts, taken with the tester in an undisturbed position between all counts, will also exhibit a standard deviation around the average of the counts or mean. Given: It is true that if the source of a series of events is truly random, then the standard deviation of 1-9