Periodici of radioactive decay

[lavinia]

I saw references on the web to periodicities in radioactive decay that are hypothesized to correspond to the varying levels of neutrinos emanating from the sun.

How do neutrinos affect radioactive decay?

 

[Drakkith]

All I've seen is this reference for wikipedia: http://news.stanford.edu/news/2010/august/sun-082310.html

 

[tiny-tim]

why does it have to be a particle?

why can't the sun produce an electroweak field, with the weak part influencing radioactive decay?

 

[sbrothy]

This was on the arxiv blog a couple of days ago. FYI:


http://arxiv.org/abs/1106.1470"

Abstract:

Unexplained annual variations in nuclear decay rates have been reported in recent years by a number of groups. We show that data from these experiments exhibit not only variations in time related to Earth-Sun distance, but also periodicities attributable to solar rotation. Additionally, anomalous decay rates coincident in time with a series of solar flares in December 2006 also point to a solar influence on nuclear decay rates. This influence could arise from some flavor of solar neutrinos, or through some other objects we call "neutrellos" which behave in some ways like neutrinos. The indication that neutrinos or neutrellos must interact weakly in the Sun implies that we may be able to use data on time-varying nuclear decay rates to probe the interior of the Sun, a technique which we may call "helioradiology".

 

[bcrowell]

The Fischbach stuff is pathological science, IMO.

FAQ: Do rates of nuclear decay depend on environmental factors?

There is one environmental effect that has been scientifically well established for a long time. In the process of electron capture, a proton in the nucleus combines with an inner-shell electron to produce a neutron and a neutrino. This effect does depend on the electronic environment, and in particular, the process cannot happen if the atom is completely ionized.

Other claims of environmental effects on decay rates are crank science, often quoted by creationists in their attempts to discredit evolutionary and geological time scales.

He et al. (He 2007) claim to have detected a change in rates of beta decay of as much as 11% when samples are rotated in a centrifuge, and say that the effect varies asymmetrically with clockwise and counterclockwise rotation. He believes that there is a mysterious energy field that has both biological and nuclear effects, and that it relates to circadian rhythms. The nuclear effects were not observed when the experimental conditions were reproduced by Ding et al.

Jenkins and Fischbach (2008) claim to have observed effects on alpha decay rates at the 10^-3 level, correlated with an influence from the sun. They proposed that their results could be tested more dramatically by looking for changes in the rate of alpha decay in radioisotope thermoelectric generators aboard space probes. Such an effect turned out not to exist (Cooper 2009). Undeterred by their theory's failure to pass their own proposed test, they have gone on to publish even kookier ideas, such as a neutrino-mediated effect from solar flares, even though solar flares are a surface phenomenon, whereas neutrinos come from the sun's core. An independent study found no such link between flares and decay rates (Parkhomov 2010). Jenkins and Fischbach's latest claims, in 2010, are based on experiments done decades ago by other people, so that Jenkins and Fischbach have no first-hand way of investigating possible sources of systematic error. Laboratory experiments[Lindstrom 2010] have also placed limits on the sensitivity of radioactive decay to neutrino flux that rule out a neutrino-mediated effect at a level orders of magnitude less than what would be required in order to explain the variations claimed in [Jenkins 2008].

Cardone et al. claim to have observed variations in the rate of alpha decay of thorium induced by 20 kHz ultrasound, and claim that this alpha decay occurs without the emission of gamma rays. Ericsson et al. have pointed out multiple severe problems with Cardone's experiments.

He YuJian et al., Science China 50 (2007) 170.

YouQian Ding et al., Science China 52 (2009) 690.

Jenkins and Fischbach (2008), http://arxiv.org/abs/0808.3283v1

Jenkins and Fischbach (2009), http://arxiv.org/abs/0808.3156

Jenkins and Fischbach (2010), http://arxiv.org/abs/1007.3318

Parkhomov, http://arxiv.org/abs/1006.2295

Cooper (2009), http://arxiv.org/abs/0809.4248

Lindstrom et al. (2010), http://arxiv.org/abs/1006.5071

F. Cardone, R. Mignani, A. Petrucci, Phys. Lett. A 373 (2009) 1956

Ericsson et al., Comment on "Piezonuclear decay of thorium," Phys. Lett. A 373 (2009) 1956, http://arxiv4.library.cornell.edu/abs/0907.0623

Ericsson et al., http://arxiv.org/abs/0909.2141

 

[Nuclear Ape]

The Fischbach stuff is pathological science, IMO.

FAQ: Do rates of nuclear decay depend on environmental factors?

There is one environmental effect that has been scientifically well established for a long time. In the process of electron capture, a proton in the nucleus combines with an inner-shell electron to produce a neutron and a neutrino. This effect does depend on the electronic environment, and in particular, the process cannot happen if the atom is completely ionized.

Other claims of environmental effects on decay rates are crank science, often quoted by creationists in their attempts to discredit evolutionary and geological time scales.

He et al. (He 2007) claim to have detected a change in rates of beta decay of as much as 11% when samples are rotated in a centrifuge, and say that the effect varies asymmetrically with clockwise and counterclockwise rotation. He believes that there is a mysterious energy field that has both biological and nuclear effects, and that it relates to circadian rhythms. The nuclear effects were not observed when the experimental conditions were reproduced by Ding et al.

Jenkins and Fischbach (2008) claim to have observed effects on alpha decay rates at the 10^-3 level, correlated with an influence from the sun. They proposed that their results could be tested more dramatically by looking for changes in the rate of alpha decay in radioisotope thermoelectric generators aboard space probes. Such an effect turned out not to exist (Cooper 2009). Undeterred by their theory's failure to pass their own proposed test, they have gone on to publish even kookier ideas, such as a neutrino-mediated effect from solar flares, even though solar flares are a surface phenomenon, whereas neutrinos come from the sun's core. An independent study found no such link between flares and decay rates (Parkhomov 2010). Jenkins and Fischbach's latest claims, in 2010, are based on experiments done decades ago by other people, so that Jenkins and Fischbach have no first-hand way of investigating possible sources of systematic error. Laboratory experiments[Lindstrom 2010] have also placed limits on the sensitivity of radioactive decay to neutrino flux that rule out a neutrino-mediated effect at a level orders of magnitude less than what would be required in order to explain the variations claimed in [Jenkins 2008].

I'm sensing, Ben, that you really didn't read those articles. The Lindstrom paper did set a possible limit on nubar-e interactions, but the solar neutrinos which Jenkins, Fischbach & Sturrock claim could be causing this effect are not nubar-e, but are neutrinos, and could be electron, mu or taus. deMeijer, Blaauw and Smit also did a nice experiment (http://www.sciencedirect.com/science/article/pii/S096980431000312X) where reactor anti-neutrinos were not shown to have a similar effect.

The Cooper paper you mentioned did not show an effect, certainly, but that was looking at Pu-238 decay (which alpha-decays to U-234, which also alpha decays...). So far, the effect proposed by Jenkins and Fischbach has been exclusively seen in beta-decays. So, really, Cooper has shown nothing unusual or unexpected.

Interesting that you quote the paper by Parkhomov that found no association with solar flares. I've read that paper, and while it's true that he found nothing, Jenkins and Fischbach also didn't so a significant change in their decay rates related to the X-9 flare at the beginning of Dec 2006 (5 Dec, the changes they saw were associated with the flares from 13-17 Dec). However, Parkhomov also wrote another paper, where he sees the same things as Jenkins and Fischbach (http://arxiv.org/abs/1012.4174) in beta-decays, yet does not see them in alphas.

I don't see this as a closed issue, certainly. Anyone who looks at it that way is not paying attention to the details.

 

[bcrowell]

I'm sensing, Ben, that you really didn't read those articles.

I did. The whole thing is the worst kind of incompetent science. Total kook stuff. Extraordinary claims without even marginal evidence. It's always depressing when peer review breaks down completely. I'm sure Astroparticle Physics will end up deeply embarrassed at having been taken in by this nonsense. It's sad, because I've collaborated with grad students from Purdue on nuclear physics experiments, and I had a very good impression of their program. This kind of thing will inevitably taint the reputation of anyone coming out of Purdue in the future with a PhD in experimental nuclear physics.

-Ben

 

[Drakkith]

I'm on bcrowell's side due to the lack of evidence in support of Jenkins and Fischbach by anyone but themselves that I've seen. If you would like to perform some experiments, feel free.

 

[bcrowell]

I'm sensing, Ben, that you really didn't read those articles. The Lindstrom paper did set a possible limit on nubar-e interactions, but the solar neutrinos which Jenkins, Fischbach & Sturrock claim could be causing this effect are not nubar-e, but are neutrinos, and could be electron, mu or taus. deMeijer, Blaauw and Smit also did a nice experiment (http://www.sciencedirect.com/science/article/pii/S096980431000312X) where reactor anti-neutrinos were not shown to have a similar effect.

This is typical pathological science. When other people find contrary evidence, invent an exotic interpretation to evade it.

The Cooper paper you mentioned did not show an effect, certainly, but that was looking at Pu-238 decay (which alpha-decays to U-234, which also alpha decays...). So far, the effect proposed by Jenkins and Fischbach has been exclusively seen in beta-decays. So, really, Cooper has shown nothing unusual or unexpected.

It was clearly unusual and unexpected for Jenkins and Fischbach, who suggested this type of effect as a test of their own findings.

Interesting that you quote the paper by Parkhomov that found no association with solar flares. I've read that paper, and while it's true that he found nothing, Jenkins and Fischbach also didn't so a significant change in their decay rates related to the X-9 flare at the beginning of Dec 2006 (5 Dec, the changes they saw were associated with the flares from 13-17 Dec). However, Parkhomov also wrote another paper, where he sees the same things as Jenkins and Fischbach (http://arxiv.org/abs/1012.4174) in beta-decays, yet does not see them in alphas.

Parkhomov has peaks all over the place, proving that his experiment is subject to systematic errors of the same size as the effect he claims to have found.

 

[bcrowell]

why does it have to be a particle?

why can't the sun produce an electroweak field, with the weak part influencing radioactive decay?

Electroweak interactions are short range.

 

[Drakkith]

What is an electroweak field?

 

[bcrowell]

What is an electroweak field?

The electromagnetic field can be thought of as a classical field, as in Maxwell's equations, or as an exchange of photons. Electromagnetism can be unified with the weak nuclear interaction, and result is called the electroweak interaction. The electroweak interaction is carried by photons, W's, and Z's. Since the W's and the Z have mass, the interaction they carry falls off exponentially with distance.

-Ben

 

[bcrowell]

Nuclear Ape, are you affiliated with the Purdue group that has published these results?

 

[Drakkith]

So this electroweak field would consist of 2 fields, one of photons which obeys the inverse square law, and the w and z bosons which have an exponential decrease?

 

[bcrowell]

So this electroweak field would consist of 2 fields, one of photons which obeys the inverse square law, and the w and z bosons which have an exponential decrease?

Something sort of like that. My field theory is awfully weak. One thing to realize is that they aren't really separate fields. In E&M, the E and B fields aren't really separate; what one observer sees as a certain E and B field pattern, another in a different state of motion will see as some other combination of E and B. They're unified. Later on, the weak force was unified with E&M.

 

[Drakkith]

Hrmmm...alright then. Thanks bcrowell!