Current address: i). NASA Goddard Space Flight Center, Code 661, Greenbelt, MD 20771, USA ii). Universities Space Research Association, 7501 Forbes Blvd. #206, Seabrook, MD 20706-2253, USA.

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In the following, "primordial radioactivity'' denotes unstable isotopes that already existed when the Earth was formed.

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... detector

The D1 detector mass fraction of Fe, Cr, and Ni relative to Al is about 20%, 5%, and 6%, respectively.

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... passages

The D1 detector mass fraction of Cu relative to Al is about 13%.

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... following

This veto rate is the number of deadtime clock counts that occur during the presence of a veto signal. For each veto dome the deadtime clock counts are accumulated over the length of a telemetry packet (2.048 s) once during each superpacket (16.384 s) and recorded in the house-keeping datasets in units of [deadtime clock counts/2.048 s $\equiv$ DT].

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... CDG

A similar procedure consisting of four different fits was utilized in the CDG analysis of Kappadath et al. (2000) to determine the background contributions from the five isotopes (²D, ²²Na, ²⁴Na, ²⁸Al, and ⁴⁰K (fixed)) identified at that time.

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... interval

Ideally, the event rates due to these isotopes would be determined by fitting the two-dimensional event distribution in E₁-E₂. However, at present such two-dimensional fits are not feasible for two reasons. First, in general the statistics is not sufficient in the CDG analysis, and second, we do not yet have a reliable model of the E₁-E₂ distribution of the continuum background, which has a complex shape as it is a blend of various components.

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