Jere H. Jenkins

Evidence of correlations between nuclear decay rates and Earth-Sun distance

Abstract Unexplained periodic fluctuations in the decay rates of 32 Si and 226 Ra have been reported by groups at Brookhaven National Laboratory ( 32 Si), and at the Physikalisch–Technische–Bundesanstalt in Germany ( 226 Ra). We show from an analysis of the raw data in these experiments that the observed fluctuations are strongly correlated in time, not only with each other, but also with the time of year. We discuss both the possibility that these correlations arise from seasonal influences on the detection system, as well as the suggestion of an annual modulation of the decay rates themselves which vary with Earth–Sun distance.

Analysis of environmental influences in nuclear half-life measurements exhibiting time-dependent decay rates

Abstract In a recent series of papers evidence has been presented for correlations between solar activity and nuclear decay rates. This includes an apparent correlation between Earth–Sun distance and data taken at Brookhaven National Laboratory (BNL), and at the Physikalisch-Technische Bundesanstalt (PTB). Although these correlations could arise from a direct interaction between the decaying nuclei and some particles or fields emanating from the Sun, they could also represent an “environmental” effect arising from a seasonal variation of the sensitivities of the BNL and PTB detectors due to changes in temperature, relative humidity, background radiation, etc. In this paper, we present a detailed analysis of the responses of the detectors actually used in the BNL and PTB experiments, and show that sensitivities to seasonal variations in the respective detectors are likely too small to produce the observed fluctuations.

Power spectrum analyses of nuclear decay rates

Abstract We provide the results from a spectral analysis of nuclear decay data displaying annually varying periodic fluctuations. The analyzed data were obtained from three distinct data sets: 32 Si and 36 Cl decays reported by an experiment performed at the Brookhaven National Laboratory (BNL), 56 Mn decay reported by the Children’s Nutrition Research Center (CNRC), but also performed at BNL, and 226 Ra decay reported by an experiment performed at the Physikalisch–Technische Bundesanstalt (PTB) in Germany. All three data sets exhibit the same primary frequency mode consisting of an annual period. Additional spectral comparisons of the data to local ambient temperature, atmospheric pressure, relative humidity, Earth–Sun distance, and their reciprocals were performed. No common phases were found between the factors investigated and those exhibited by the nuclear decay data. This suggests that either a combination of factors was responsible, or that, if it was a single factor, its effects on the decay rate experiments are not a direct synchronous modulation. We conclude that the annual periodicity in these data sets is a real effect, but that further study involving additional carefully controlled experiments will be needed to establish its origin.

Additional experimental evidence for a solar influence on nuclear decay rates

Abstract Additional experimental evidence is presented in support of the recent hypothesis that a possible solar influence could explain fluctuations observed in the measured decay rates of some isotopes. These data were obtained during routine weekly calibrations of an instrument used for radiological safety at The Ohio State University Research Reactor using 36 Cl. The detector system used was based on a Geiger–Muller gas detector, which is a robust detector system with very low susceptibility to environmental changes. A clear annual variation is evident in the data, with a maximum relative count rate observed in January/February, and a minimum relative count rate observed in July/August, for seven successive years from July 2005 to June 2011. This annual variation is not likely to have arisen from changes in the detector surroundings, as we show here.

Concerning the Time Dependence of the Decay Rate of 137Cs

The decay rates of eight nuclides ((85)Kr, (90)Sr, (108)Ag, (133)Ba, (137)Cs, (152)Eu, (154)Eu, and (226)Ra) were monitored by the standards group at the Physikalisch-Technische Bundesanstalt (PTB), Braunschweig, Germany, over the time frame June 1999 to November 2008. We find that the PTB measurements of the decay rate of (137)Cs show no evidence of an annual oscillation, in agreement with the recent report by Bellotti et al. However, power spectrum analysis of PTB measurements of a (133)Ba standard, measured in the same detector system, does show such evidence. This result is consistent with our finding that different nuclides have different sensitivities to whatever external influences are responsible for the observed periodic variations.In a recent posting to the arXiv, Norman [1] raises an interes ting question relating to the phase of the annually varying 36Cl measured decay rate as reported by two independent groups [2, 3]. He correctly notes that the apparent phases reported in [2, 3] are not identical, as might be expected in a model in which the annual decay-rate variation is attributed simply to the varying Earth-Sun distance R. These determined phases are discussed in Javorsek II et al. [4] for the Alburger et al. [2] dat a, and in Jenkins et al. [3] for the second data set. (By conventi on the phase of the annual variation is the calendar day on which the decay rate is a maximum.) In this note we address the question raised by Norman [1]. If the Sun were a uniform, homogeneous sphere producing energy and emitting particles (e.g. neutrinos) at a constan t, uniform rate, and the observed periodicities were due solel y to the eccentricity of the Earth’s orbit around the Sun, then the expected phase of decay data would be either perihelion (∼January 4) or aphelion ( ∼July 4) depending on the (as yet unknown) dynamics of the decay progress. However, most of the nuclides for which measured decay data are currently ava ilable exhibit a phase closer to mid-February, rather than Jan uary 4. Hence our first task is to understand the origin of the midFebruary phase. In Ref. [5] we propose that this phase arises from a combination of two annually varying e ff cts: the 1/R2 variation arising from the ellipticity of the Earth’s orbit around the Sun, and a North-South (latitudinal) asymmetry in neutr ino production or propagation occurring in the Sun itself, for w hich there is considerable independent evidence [6–11]. This ph a e shift from perihelion has been seen in the phase determinati ons of two major solar neutrino observatories, as described in R efs. [12–15]. As we note in Ref.[5] the North-South asymmetry e ffect alone would yield a phase ∼March 10 (or September 10) due to the 7 tilt of the solar axis of rotation relative to the ecliptic. In this picture the mid-February phase would then resul t by combining the 1/R2 effect (∼ January 4) and the North-South asymmetry (March 10) with appropriate relative weights. Si nce any North-South asymmetry would be expected to be a variable

Spectral content of 22Na/44Ti decay data: implications for a solar influence

We report a reanalysis of data on the measured decay rate ratio 22Na/44Ti which were originally published by Norman et al., and interpreted as supporting the conventional hypothesis that nuclear decay rates are constant and not affected by outside influences. We find upon a more detailed analysis of both the amplitude and the phase of the Norman data that they actually favor the presence of an annual variation in 22Na/44Ti, albeit weakly. Moreover, this conclusion holds for a broad range of parameters describing the amplitude and phase of an annual sinusoidal variation in these data. The results from this and related analyses underscore the growing importance of phase considerations in understanding the possible influence of the Sun on nuclear decays. Our conclusions with respect to the phase of the Norman data are consistent with independent analyses of solar neutrino data obtained at Super-Kamiokande-I and the Sudbury Neutrino Observatory (SNO).

Searches for solar-influenced radioactive decay anomalies using spacecraft RTGs

Abstract Experiments showing a seasonal variation of the nuclear decay rates of a number of different nuclei, and decay anomalies apparently related to solar flares and solar rotation, have suggested that the Sun may somehow be influencing nuclear decay processes. Recently, Cooper searched for such an effect in 238 Pu nuclei contained in the radioisotope thermoelectric generators (RTGs) on board the Cassini spacecraft. In this paper we modify and extend Cooper’s analysis to obtain constraints on anomalous decays of 238 Pu over a wider range of models, but these limits cannot be applied to other nuclei if the anomaly is composition-dependent. We also show that it may require very high sensitivity for terrestrial experiments to discriminate among some models if such a decay anomaly exists, motivating the consideration of future spacecraft experiments which would require less precision.

Analysis of Beta-Decay Rates for

We present the results of an analysis of measurements of the beta-decay rates of Ag108, Ba133, Eu152, Eu154, Kr85, Ra226, and Sr90 acquired at the Physikalisch-Technische Bundesanstalt from 1990 through 1995. Although the decay rates vary over a range of 165 to 1 and the measured detector current varies over a range of 19 to 1, the detrended and normalized current measurements exhibit a sinusoidal annual variation with amplitude in the small range 0.068% to 0.088% (mean 0.081%, standard deviation 0.0072%, an 11{\sigma} rejection of the zero-amplitude hypothesis) and phase-of-maximum in the small range 0.062 to 0.083 (January 23 to January 30). In comparing these results with those of other related experiments that yield different results, it may be significant that this experiment, at a standards laboratory, seems to be unique in using a 4{\pi} detector. These results are compatible with a solar influence, and appear not to be compatible with an experimental or environmental influence. It is possible that Ba133 measurements are subject also to a non-solar (possibly cosmic) influence.

^{108}

We report the results of an experiment to determine whether the half-life of {sup 198}Au depends on the shape of the source. This study was motivated by recent suggestions that nuclear decay rates may be affected by solar activity, perhaps arising from solar neutrinos. If this were the case then the {beta}-decay rates, or half-lives, of a thin foil sample and a spherical sample of gold of the same mass and activity could be different. We find for {sup 198}Au, (T{sub 1/2}){sub foil}/(T{sub 1/2}){sub sphere} = 0.999 {+-} 0.002, where T{sub 1/2} is the mean half-life. The maximum neutrino flux at the sample in our experiments was several times greater than the flux of solar neutrinos at the surface of the Earth. We show that this increase in flux leads to a significant improvement in the limits that can be inferred on a possible solar contribution to nuclear decays.

Ag,

We have analyzed 137Cs decay data, obtained from a small sample onboard the MESSENGER spacecraft en route to Mercury, with the aim of setting limits on a possible correlation between nuclear decay rates and solar activity. Such a correlation has been suggested recently on the basis of data from 54Mn decay during the solar flare of 13 December 2006, and by indications of an annual and other periodic variations in the decay rates of 32Si, 36Cl, and 226Ra. Data from five measurements of the 137Cs count rate over a period of approximately 5.4 years have been fit to a formula which accounts for the usual exponential decrease in count rate over time, along with the addition of a theoretical solar contribution varying with MESSENGER-Sun separation. The indication of solar influence is then characterized by a non-zero value of the calculated parameter ξ, and we find ξ=(2.8±8.1)×10−3 for 137Cs. A simulation of the increased data that can hypothetically be expected following Mercury orbit insertion on 18 March 2011 suggests that the anticipated improvement in the determination of ξ could reveal a non-zero value of ξ if present at a level consistent with other data.