Time-Series Analysis of Reconstructed DAMA Data

Abstract

An analysis of DAMA data (as reconstructed from DAMA publications) confirms the presence of an annual oscillation, but with a lower significance level than that claimed by DAMA. The phase of their signal is 0.39 +/- 0.02, corresponding to a peak value at about May 22, which is consistent with both the DAMA estimate and the expected phase of a dark-matter signal. However, a spectrogram analysis also shows evidence for oscillations in the frequency band 11 - 13 year-1, that are similar to oscillations found in spectrograms formed from measurements of the decay rates of 36Cl and 32Si acquired at the Brookhaven National Laboratory (BNL). One component of these oscillations (at 11.44 year-1) is prominent in DAMA/NaI data, at the 0.2% significance level (99.8% confidence level). Analyses of BNL and other nuclear decay (specifically beta decay and K-capture) measurements point to a solar influence, either by neutrinos or by some currently unknown form of radiation. The phase of the annual oscillation in DAMA data is compatible with an influence of dark matter, and is unlikely to be attributable to a purely solar influence. We also find that annual oscillations in both 133Ba decay measurements and the Troitsk tritium-decay measurements are compatible with a cosmic influence but not with a purely solar influence. These considerations raise the possibility that DAMA measurements may somehow be influenced by a combination of solar neutrinos, cosmic neutrinos, and dark matter