Generalized Lomb–Scargle analysis of $$\mathrm {^{36}Cl}$$ decay rate measurements at PTB and BNL

Abstract

Recently Pomme et al. [1] did an analysis of 36 Cl radioactive decay data from measurements at the Physikalisch-Technische Bundesanstalt (PTB), in order to verify the claims by Sturrock and collaborators of an influence on beta-decay rates measured at Brookhaven National Lab (BNL) due to the rotation-induced modulation of the solar neutrino flux. Their analysis excluded any sinusoidal modulations in the frequency range from 0.2-20/year. We carry out an independent analysis of the same PTB and BNL data, using the generalized Lomb-Scargle periodogram to look for any statistically significant peaks in the range from 0 to 14 per year, and by evaluating the significance of every peak using multiple methods. Our results for the PTB data are in agreement with those by Pomme et al. For BNL data, we do find peaks at some of the same frequencies as Sturrock et al., but the significance is much lower. All our analysis codes and datasets have been made publicly available. PACS numbers: 26.65+t, 95.75.Wx, 14.60.St, 96.60.Vg * ep15btech11005@iith.ac.in †

Generalized Lomb–Scargle analysis of $${^{123}\mathrm{I}}$$ and $${^{99\mathrm{m}}\mathrm{Tc}}$$ decay rate measurements

“…To independently verify some of these claims, we have analyzed some of the betadecay and solar neutrino data ourselves using robust statistical methods, for whatever data was accessible or made publicly available. Our analysis shows periodicities associated with solar rotation and annual modulation, although with a lower significance than claimed in some of the original works [23][24][25].…”

“…For this purpose, we used the generalized or floating-mean L-S periodogram [30] (similar to our previous works [23][24][25]), as it is more sensitive than the ordinary L-S periodogram, which was used in B18. We searched for statistically significant peaks for both these nuclei upto five times the Nyquist frequency.…”

“…We calculate the statistical significance of the most significant peak as well as other periods deemed interesting in literature, such as annual variation, solar rotation [4,31], using multiple methods. For this analysis, we use the same methodology as in our previous work [25].…”

Search for periodic modulations of the rate of double- β decay of Mo100 in the NEMO-3 detector

“…Some of the previously mentioned dark matter searches, e.g., [22][23][24] and radioactive decay analyses, e.g., [36][37][38][39] and [44] have used LS periodogram analyses similar or identical to the approach used herein. Other examples also include searches for periodic variations in neutrino fluxes across various experiments, e.g., [55][56][57][58][59][60], while uses of the GLS periodogram appear in other recent analyses [47,61,62].…”

“…Also controversial are results of a posteriori data analyses of measurements of nuclear decay half-lives which have yielded unexpected periodicities, including annual modulations that authors have linked to the periodicity of the Earth-Sun distance and solar activity [33][34][35][36][37][38][39][40][41][42][43][44]. However, other analyses of the same data do not reveal any significant modulations [45][46][47].…”