The half-life of 137Cs- A critical review

Woods, M.J.

doi:10.1016/0168-9002(90)90919-w

Cited by 13 publications

(5 citation statements)

References 13 publications

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“…1-4, the existence of these effects may explain discrepancies in various half-life determinations reported in the literature. Examples are 32 Si, 44 Ti and 137 Cs, among many others [6,19,20,21]. If nuclides such as 32 Si, 36 Cl, and 226 Ra respond to changes in the solar neutrino flux due to the time-dependence of 1/R 2 , then they can also respond to changes in intrinsic solar activity which are known to occur over time scales both longer and shorter than one year.…”

Section: Fig 4: Correlation Between the Decay Rates Ofmentioning

confidence: 99%

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

Jenkins

Fischbach

Buncher

et al. 2009

Astroparticle Physics

141

109

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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-TechnischeBundesandstalt 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 distance between the Earth and the Sun. Some implications of these results are also discussed, including the suggestion that discrepancies in published half-life determinations for these and other nuclides may be attributable in part to differences in solar activity during the course of the various experiments, or to seasonal variations in fundamental constants. Following the discovery of radioactivity by Becquerel in 1896 [1] an intense effort was mounted to ascertain whether the decay rates of nuclides could be affected by external influences including temperature, pressure, chemical composition, concentration, and magnetic fields. By 1930, Rutherford, Chadwick, and Ellis [2, p. 167] concluded that "The rate of transformation of an element has been found to be a constant under all conditions." (For decays resulting from K-capture, or for beta-decays in strong ambient electromagnetic fields, the situation is slightly more complicated, since these decays are influenced by the electron wave functions which can be affected by external pressure or fields [3,4,5].) For 32 Si and 226 Ra, which decay by beta-and alpha-emission, respectively, fluctuations in the counting rates (in the absence of strong external electromagnetic fields) should thus be uncorrelated with any external time-dependent signal, as well as with each other. In what follows we show that neither of these expectations is realized in data we have analyzed for 32 Si and 226 Ra, thus suggesting that these decays are in fact being modulated by an external influence.Between 1982 and 1986, Alburger, et al. [6] measured the half-life of 32 Si at Brookhaven National Laboratory (BNL) via a direct measurement of the counting rate as a function of time. If N (t) denotes the number of surviving atoms starting from an initial population N 0 at t = 0, then the familiar exponential decay law, N (t) = N 0 e −λt , leads toṄ ≡ dN/dt = −λN 0 e −λt where λ = ln(2)/T 1/2 . A plot of ln Ṅ (t) as a function of time is then a straight line whose slope is λ, which then gives the half-life T 1/2 . At the time this experiment was initiated, the 32 Si half-life was believed to be in the range of 60 T 1/2 700 yr, and hence a multiyear counting experiment was needed to obtain a measureable slope. As in other counting experiments, the counting rate for 32 Si was continually monitored in the same detector against a long-lived comparison standard, which in the BNL experiment was 36 Cl (T 1/2 =301,000 yr). Since the fractional change in the 36 Cl counting rate over the four year duration of the experiment was only O(10 −5 ), which was considerably smaller than the overall uncertainty of the final res...

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Section: Fig 4: Correlation Between the Decay Rates Ofmentioning

confidence: 99%

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

Jenkins

Fischbach

Buncher

et al. 2009

Astroparticle Physics

141

109

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“…Source A: Wilson (1966); Source B: Tuli (1985); Source C: Winter (1999 These observations were communicated to the National Physical Laboratory (NPL), Teddington, UK. Their reply confirmed that the accuracy of measurement of radioisotope half lives was sometimes subject to considerable uncertainty (Woods 1990, Woods andLucas 1996).…”

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confidence: 83%

“…Essentially there are two methods of measuring radioisotope half lives; one is direct measurement of the decay, the other is from a measurement of the specific activity. The former method is generally regarded as being potentially the most reliable (Woods 1990), but is obviously unsuitable for the measurement of very long half lives. The latter method is used for long-lived radioisotopes but is subject to greater uncertainties arising from a variety of causes, and which are often difficult to quantify.…”

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confidence: 99%

Reliability of published data on radionuclide half lives - relevance to the use of reference sources for checking instrument performance

Waldock¹

1999

Phys. Med. Biol.

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Long-lived calibrated radioisotopes are frequently used for checking of instrumentation used in the measurement of radiation; examples include: radioisotope assay meters, radiation monitors and sample counting equipment. In 1986 we purchased a radioisotope calibrator (Capintec CRC120) which was supplied with a number of long-lived check sources by the manufacturer, one of which was barium-133. The source came with its own calibration certificate and a quoted half life of 10.74 years ± 0.05 years, traceable to the National Bureau of Standards in the USA, and is consistent with data published by the National Nuclear Data Center, Brookhaven National Laboratory in 1985 (Tuli 1985). However, we noted at the time that this is significantly different to the value of 7.2 years quoted in the Radiochemical Manual (Wilson 1966) published by the Radiochemical Centre, Amersham (now Nycomed-Amersham), and more recently we have noted that it is significantly different to the value of 10.53 years currently quoted on various Internet sites including the University of Sheffield Chemistry Department (Winter 1999). Further investigation showed similar or worse variations of published half lives with time for several radioisotopes, as indicated in table 1.

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“…A simple search of the literature reveals multiple instances of articles discussing the discrepancies in nuclear decay measurements, particularly half-life determinations. 32,33,34,35 It is interesting, given recent advances in detector technology, and the precision with which we can make measurements in the present day, that there would be discrepancies as large as are observed to be present in nuclear decay data. However, if some of these measurements are of β − decays that are affected by an influence external to the Earth, and this influence has a variable output, then the picture becomes a little clearer.…”

Section: Review Of Experimental Evidencementioning

confidence: 99%

Analysis of Experiments Exhibiting Time-Varying Nuclear Decay Rates: Systematic Effects or New Physics?

Jenkins,

Fischbach,

Sturrock

et al. 2011

Preprint

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Since the 1930s, and with very few exceptions, it has been assumed that the process of radioactive decay is a random process, unaffected by the environment in which the decaying nucleus resides. There have been instances within the past few decades, however, where changes in the chemical environment or physical environment brought about small changes in the decay rates. But even in light of these instances, decaying nuclei that were undisturbed or un-"pressured" were thought to behave in the expected random way, subject to the normal decay probabilities which are specific to each nuclide. Moreover, any "non-random" behavior was assumed automatically to be the fault of the detection systems, the environment surrounding the detectors, or changes in the background radiation to which the detector was exposed. Recently, however, evidence has emerged from a variety of sources, including measurements taken by independent groups at Brookhaven National Laboratory, Physikalisch-Technische Bundesanstalt, and Purdue University, that indicate there may in fact be an influence that is altering nuclear decay rates, albeit at levels on the order of 10 −3 . In this paper, we will discuss some of these results, and examine the evidence pointing to the conclusion that the intrinsic decay process is being affected by a solar influence.

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The half-life of 137Cs- A critical review

Cited by 13 publications

References 13 publications

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

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

Reliability of published data on radionuclide half lives - relevance to the use of reference sources for checking instrument performance

Analysis of Experiments Exhibiting Time-Varying Nuclear Decay Rates: Systematic Effects or New Physics?

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