This paper discusses calculational methods for the determination of the difference distributions associated with certain health physics measurements. These measurements include the check-source response counts relative to an initial reference count, the Albatross (i.e., HPI model 2080B) neutron tube counts relative to the gamma tube counts, and those that involve the use of the automatic background subtraction feature of portable health physics instrumentation. Examples are provided that illustrate the methods for a few specific measurements. For the comparison of a daily source count to its previously determined reference value, minimum counts for various scenarios were presented in order to reliably meet required tolerance limits of ±10% and ±20%. In either case, it was found beneficial that the initial reference readings be established using a counting interval of longer length than the daily interval. For the comparison of Albatross neutron counts to the gamma counts, it was seen that the relative error in the difference distribution was still related to that of the parent distribution. It was seen, therefore, that an effective way of reducing the gamma influence on the Albatross was to increase the counting interval used, hence yielding a significantly larger mean count per interval. For the automatic background subtraction feature, it was noted that net count values near 0 counts would almost always have the negative values of the difference distribution truncated to 0 counts by commercially available off-the-shelf instrumentation, whereas significant net count values would be displayed correctly but with a larger associated variance than the gross count itself. This paper therefore also provides a technical basis for the necessary source strength of a check source in order to meet daily limits, the gamma field limitations of the HPI 2080B Albatross, as well as the consequences of automatic background subtraction.

中文翻译：

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适用于某些健康物理测量的差异分布

本文讨论了确定与某些健康物理测量相关的差异分布的计算方法。这些测量包括相对于初始参考计数的检查源响应计数，相对于伽马管计数的信天翁（即HPI 2080B型）中子管计数，以及涉及使用便携式医疗的自动本底扣除功能的测量物理仪器。提供的示例说明了一些特定测量的方法。为了将每日源计数与其先前确定的参考值进行比较，提出了各种情况下的最小计数，以便可靠地满足所需的±10％和±20％的公差范围。在任何一种情况下，发现使用比日间间隔更长的计数间隔来建立初始参考读数是有益的。为了比较信天翁中子计数和伽玛计数，可以看出差异分布的相对误差仍与母体分布的相对误差有关。因此，可以看出，减少伽玛射线对信天翁的影响的有效方法是增加所用的计数间隔，从而使每个间隔的平均计数显着提高。工具，而重要的净计数值将正确显示，但相关的方差大于总计数本身。因此，本文还为满足日常限制，HPI 2080B Albatross的伽马场限制以及自动背景扣除的后果提供了必要的检查源强度技术基础。