Current Status and Future Prospects of the SNO+ Experiment

Table 2

Target levels, in g/g, and corresponding decay rates for the internal ²³⁸U- and ²³²Th-chain contaminants in the various SNO+ phases. Secular equilibrium has been assumed for all the isotopes except ²¹⁰Pb, ²¹⁰Bi, and ²¹⁰Po. The levels of ²¹⁰Bi and ²¹⁰Po during the pure scintillator phase and the Te-loaded phase are expected to be out of secular equilibrium due to the intrinsic scintillator contamination and the leaching off of the AV surface. For the 0.3% Te-loaded scintillator the tellurium/polonium affinity component is also included in the ²¹⁰Po decays/yr (see text).

Source	Target [g/g]	Decays/yr
Internal H2O, water phase
^238U chain	3.5 × 10^−14	1.2 × 10^7
^232Th chain	3.5 × 10^−15	4.1 × 10^5
LAB-PPO, pure scintillator phase
^238U chain	1.6 × 10^−17	4900
^232Th chain	6.8 × 10^−18	700
^210Bi	—
^210Po	—
0.3% Te-loaded scintillator, Te phase
^238U chain		7.6 × 10^5
^232Th chain	2.8 × 10^−16	2.8 × 10^4
^210Bi	—
^210Po	—

Expected number of events in the first year after 9 months of water phase.
Expected number of events in the first year after 9 months of water phase followed by 6 months of pure scintillator phase.