The Purcell effect

  • Purcell effect


    https://en.wikipedia.org/wiki/Purcell_effect


    For particle physicists whose entire standard model assumes that decay rates cannot be influenced by external factors, the Purcell effect is a puzzle.


    The Purcell effect is a condition that has perplexed science which lays smack dab in the middle of one of the miracles of the LENR reaction. In science, It has long been asserted that nuclear decay rates are constant and cannot be affected by anything.


    https://www.sciencedaily.com/r…/2014/10/141010083857.htm

    Old textbook knowledge reconfirmed: Decay rates of radioactive substances are constant


    This assertion has been used by the critics of the LENR reaction to undercut the validity of what experiments have shown when the LENR reaction was in progress.


    But the Purcell effect discounts the logic of this LENR criticism. The Purcell effect states that the decay rate of a radioactive isotope is affected by light trapped in an optical cavity. This nuclear decay rate can either increase or decrease by a factor up to 50 times.


    https://physics.aps.org/synops…03/PhysRevLett.120.122501

    Controlling the Rate of Nuclear Decay


    The maximum effect is achieved when a dark mode of light emissions from the optical cavity is achieved. This mode is when light is maintained inside the cavity and does not radiate out. An important condition that must exist in both the LENR reaction and the Purcell effect is that this effect exists in nano-cavities in metal.


    But what is more disconcerting is that the nuclear decay rate can either increase or decrease by a factor of 50.


    There is something that exists in an optical cavity that can affect nuclear processes. What can it be and how does it do it.


    Well it is our old LENR friend, the Surface Plasmon Polariton (SPP). The SPP can produce nuclear effects and does it best when it is in dark mode. But how can the SPP stop a radioactive isotope from decaying?


    The SPP is formed by two counter rotating currents of polaritons. These currents are polarized in terms of handedness. Right-handed particles don’t decay, only left-handed particles decay.


    https://www.nature.com/articles/524008b

    Particle physics: Only left-handed particles decay


    When a radioactive nucleus is converted by the SPP into a right handed particle, it cannot decay. But when the nucleus is converted by the SPP into a left handed particle, it decays so fast that the radioactive nucleus stabilizes immediately.


    The chirality of particles explains how LENR can stabilize radioactive waste. LENR is all about the handedness (chirality) of particles.

  • Quote

    The examples of the engineering of LENR reactors that we know about indicate that the LENR reaction is only active when the SPP stimulus is on. One of the SPP stimuli is a laser beam's iteraction with metal nano-particles. This activation mechanism, the application of light (heat) is how the LENR reactor controls the operation of the LERN reaction. In other words, when the laser beam is on then the LENR reactor is active and when the laser beam is off then the LENR reactor is off. The reason for this behavior is because the lifetime of the SPP is just a few picoseconds. This short timeframe is the effective replacement time-frame of the SPP, that is, the time it takes one SPP to die and the next SPP to replace it. With this principle in mind, consider the results of this experiment.


    I now reference a paper to show how the generation of SPPs on the surface of gold nanoparticles: a nanoplasmonic mechanism can change the half-life of U232 from 69 years to 6 microseconds when a laser beam is active and how this effect stimulus can also initiate fission in thorium.


    See references:

    http://www.google.com/url?sa=t…TUA&bvm=bv.46471029,d.dmQ



    Nothing happens when there is only a laser used with NO nanoparticles,


    Form the article:



    Quote

    The effect of exposure of the solution to different laser sources is shown in Fig. 4. One

    can see that the activity is decreased by a factor of 2 after 1 hour exposure to laser beam at intensity level of 10e12 - 10e13 W/cm2. It is reasonable to suggest that the alpha-decay proceeds during the laser pulse, while the spontaneous decrease of alpha-activity during exposure is negligible. This means that the activity drops down by a factor of 2 during 5 us, which is the total duration of all 150 ps laser pulses during exposure. In other words, the half-life of 232U in the laser field is 5 us instead of 69 years. About 10e10 nuclei of 232U decay during laser exposure.


    Another infrared laser radiation with pulse duration of 350 ps affects the alpha-activity of the solution to lesser extent despite to much higher number of laser pulses.


    In another experiment using a jet of high speed argon gas, the LENR ash produced by an electric arc at the instant of creation was radioactive, but by the time the ash traveled 100 cms in the high speed plasma, the ash was stable. LENR seems to speed up time for radioactive isotope decay.


    See


    http://www.newinflow.ru/pdf/Klimov_Poster.pdf

  • axil


    This OP is 100% false. The Purcell effect is (normally) nothing to do with radioactivity (but see below), but with photon emission from fluorescent material: that is electronic structure change - not nuclear change.


    It is VERY WELL EXPLAINED by QED - one of the very many diverse phenomena explained quantitatively and qualitatively by that incredibly successful theory. So it is also not true that physics finds it mysterious.


    From your link:


    The Purcell effect is the enhancement of a fluorescent molecule's spontaneous emission rate by its environment. In the 1940s Edward Mills Purcell discovered the enhancement of spontaneous emission rates of atoms when they are matched in a resonant cavity (the Purcell Effect). The magnitude of the enhancement is given by the Purcell factor.

    One way of seeing why this enhancement arises is by using cavity quantum electrodynamics. Fermi's golden rule dictates that the transition rate for the atom-vacuum (or atom-cavity) system is proportional to the density of final states. In a cavity at resonance, the densityof final states is enhanced (though the number of final states may not be). The Purcell factor is then just the ratio of the cavity

    \rho_c = \frac{1}{\Delta \nu V}

    to that of the free space density of states

    \rho_f = \frac{8\pi n^3 \nu^2}{c^3}



    Q=\nu / \Delta \nu


    we get that



    {\displaystyle \rho _{c}/\rho _{f}={\frac {c^{3}}{8\pi n^{3}\nu ^{2}}}{\frac {Q}{\nu V}}={\frac {1}{8\pi }}\left({\frac {\lambda }{n}}\right)^{3}\left({\frac {Q}{V}}\right)}


    which is correct up to a constant.


    ----------------------------------------------------------


    Also not mysterious, and predicted theoretically, nuclear reactions that emit photons can have rate affected by the e-m environment (because this changes the density of available product states).


    From Axil's other link:


    It has been predicted theoretically   that a 'photonic' material environment can control the rate of radiative recombination of an embedded light source. A main research goal is the achievement of a material with a complete photonic bandgap: a range of frequencies in which no electromagnetic modes exist and all propagation directions are forbidden. At the frequencies of the photonic bandgap, spontaneous emission of light is completely inhibited. Fabrication of a material with a complete photonic bandgap is a huge scientific challenge. For this reason photonic materials are being extensively studied. Many different kinds of systems in which the rate of spontaneous emission is modified by the environment are reported, including cavities, two,  and three-dimensional photonic bandgap materials.

    The Purcell effect can also be useful for modeling single-photon sources for quantum cryptography. Controlling the rate of spontaneous emission and thus raising the photon generation efficiency is a key requirement for quantum dot based single-photon sources.


    Atomic clocks—the gold standard in timekeeping—depend on transitions between the electronic energy levels of an atom. Recent proposals, however, suggest that atomic clocks that rely on a nuclear transition, rather than on an electronic one, could provide even greater accuracy. Currently, the best candidate nucleus is the radioactive element thorium-229. Achieving the best precision, however, will require the ability to control the rate of the nuclear transition. Now Eugene Tkalya of Moscow State University has proposed that this could be done by embedding thorium-229 in a cavity or a thin film.

    It’s well known that the rate of spontaneous emission of an atom or a molecule can change depending on the electromagnetic modes of the environment in which the particle is placed. This so-called Purcell effect, which is routinely observed in optical cavities, should, in principle, affect nuclear transitions in the same way. However, the frequency of the radiation emitted in most nuclear transitions is too large compared with the frequencies of the electromagnetic modes of typical optical cavities. Thorium-229 is an exception because it has the lowest-known nuclear transition energy.

    Tkalya theoretically analyzed how different electromagnetic environments affect the rate at which the nucleus of thorium-229 decays from its lowest excited nuclear state via emission of a gamma-ray photon. He found that when the atom is embedded in a dielectric sphere or a thin film, its decay rate can increase or decrease by a factor of up to 50, depending on the size of the enclosure. Slowing this decay rate would narrow the emission line of the nuclear transition, which, in turn, could boost the accuracy of a nuclear clock based on such a transition.


    What might make this effect relevant to LENR? You'd need a decay reaction with a photonic product. And then the reaction rate has a 2 OOM change. There are a number of other effects (e.g. high local e-m fields, as from lasers) that change reaction rate. I can't see any coherence here with LENR since the class of reactions this applies to is limited and it is a quantitatively small effect.



  • What might make this effect relevant to LENR? You'd need a decay reaction with a photonic product. And then the reaction rate has a 2 OOM change. There are a number of other effects (e.g. high local e-m fields, as from lasers) that change reaction rate. I can't see any coherence here with LENR since the class of reactions this applies to is limited and it is a quantitatively small effect.






    The energy potential of the SPP, a product of an optical cavity, can be amplified by huge factors based on superradence.


    https://en.wikipedia.org/wiki/Superradiance


    This energy amplification mechanism is a natural product of polariton non-equilibrium Bose condensation. Coherence among an aggregation of polaritons is unavoidable.


    Placing a radioactive isotope on a nickel plate will not affect the decay rate of the isotope. But when a LENR fuel is prepared, the strictures that support the amplification of the energy potential of the SPP becomes manifest, The LENR reaction is supported by a complex infrastructure of layered support structures of which the SPP is its most basic actor.


    For example, heavy loading of deuterium in palladium produces ultra dense deutrium - a natural support mechanism for Bose condensation. This molecule is superconductive which supports an ideal surface environment on its electron spin wave cover upon which SPPs can thrive. This superconductive mechanism can also be found in the LION reactor. But diamond is the material that produces the ultra dense deuterium after a mouth of soaking.


  • Axil, the Purcell effect has no relation to the ambient e-m radiation amplitude.


    Sure - ultra-high intensity radiation will create local fields high enough to affect decay. but that is not the topic of this thread - Purcell effect.

  • The Purcell affect needs a cavity with size exactly matched to the gamma frequency emitted. It is thus a really bad candidate for the type of NAE-cavities that Axil and many others interested in LENR possibilities seem to think are important. they have random uncontrolled volumes, which, also, are quite the wrong size (much too large) to couple well to typical gammas from nuclear reactions.


    Unfiltered speculation drowns out possible ideas in impossible noise: so I'm all for filtering when this can be done.

  • Axil, the Purcell effect has no relation to the ambient e-m radiation amplitude.


    Sure - ultra-high intensity radiation will create local fields high enough to affect decay. but that is not the topic of this thread - Purcell effect.


    The operative phase is "its decay rate can increase or decrease by a factor of up to 50, depending on the size of the enclosure"


    This says that the Purcell effect can increase of decrease the decay rate of a radioactive isotope by 50 times. This means that specially formatted light can produce changes in the nucleus. This means that nuclear decay rates can change.

  • The Purcell affect needs a cavity with size exactly matched to the gamma frequency emitted.


    The experimenter varied the size of the cavity over a wide range and still saw change in nuclear decay rates. There may be an optimum resonant cavity size where the nuclear decay rate change is optimized, but that effect is not signification when the power pumped into the SPP is 30 orders of magnetite greater than the effect seen at the unamplified resonate cavity size.

  • The experimenter varied the size of the cavity over a wide range and still saw change in nuclear decay rates. There may be an optimum resonant cavity size where the nuclear decay rate change is optimized, but that effect is not signification when the power pumped into the SPP is 30 orders of magnetite greater than the effect seen at the unamplified resonate cavity size.


    Axil. You are doing this again. Purcell effect has nothing to do with power pumped into a cavity, so why do you keep on confusing the two?

  • Axil. You are doing this again. Purcell effect has nothing to do with power pumped into a cavity, so why do you keep on confusing the two?


    When a LENR reactor is heated to 1000C, heat is pumping the SPP formed inside of optical cavities. I chose to term the effect that exist in those cavities Purcell. why is this not possible? At what power density in the cavity does the space inside the cavity turn away from the Purcell effect? Please provide a reference.

  • When a LENR reactor is heated to 1000C, heat is pumping the SPP formed inside of optical cavities. I chose to term the effect that exist in those cavities Purcell. why is this not possible? At what power density in the cavity does the space inside the cavity turn away from the Purcell effect? Please provide a reference.


    axil: I refer you to your first link above which defines the Purcell effect as observed and understood theoretically.


    If you choose to coin a word for some new effect you believe exists due to SPPs in microcavities which you believe achieve Qs in the billions and thus local e-m fields that are interact nonlinearly (in fact that is the main reason why such high Qs are implausible) and in novel ways. That is fine; but don't confuse it with something different that already has a word. Also, I can't see why (for this new effect) you are linking info about the Purcell effect.

  • Axil, THH & others,


    According to Holmlid, ultra-dense deuterium decays via the weak force in mesons. What is surprising here is less the occurence of a weak decay - given the length and time scales at play - than the absence of the usual D-D fusion and decay via the fast strong interaction.


    Does anyone know a process that could prevent the decay of an excited D-D via the strong force?

  • Still likely listed as a hypothesis but the mixing of material shielding -A proton (charge +e, mass mp), a deuteron (charge +e, mass 2mp), and an alpha particle, (charge +2e, mass 4mp) are accelerated through a common potential difference ΔV. Each of the particles enters a uniform magnetic field B, with its velocity in a direction perpendicular to B....etcetera. non uniform field. maybe...

  • The way I think of it.

    Steel aluminum and carbon

    Mixing steel and aluminum create galvanic corrosion and in dust form happens rapidly. \


    add the mix in a clay ceramic with carbon at 5% clay.the rate of decay is about the same

    if it was in a pile on the floor.


    If this was the first 1" at the center of a 12" ball.

    each new layered inch of new material PPMs of the mix are changed,it will change the rate of the expansion from the first 1" core.

    Given a path to exit for the sake of theory if the mix was hot, the inner core would escape quickly leaving the remaining reaction within the

    inner wall.


    The reaction would not likely continue using the path of the now gone highly galvanically eroded path the reaction now has a

    slower rate new mix of PPMs to keep the reaction going.


    If a magnetic field catalyst outside the 12" ball as a control can now be a variable rate cell that can be

    manipulated to faster or slower degradtion.


    I'm sure this is written down someplace on the net but I can't find it.

  • http://www.techtimes.com/artic…ish-red-planet-colony.htm


    New Human Subspecies Likely To Emerge As Martian Planners Try To Establish Red Planet Colony


    It is now recognized that the radiation environment in space and on extraterrestrial colonies need permanent protection from long term exposure to radiation.


    A LENR reactor could provide this protection by generating a radiation proof shield around space travelers and colonists.


    The method for generating this shield is based on the chirality of the particles that are produced by the LENR reaction. A fluid running through the LENR reactor would be chiral polarized to left handedness. The fluid could then circulate inside a network that would carry this polarization to the outer shell that enclosed the living volume of the spacefarer. The chiral polarized fluid would transfer its left handed particle properties to the material that makes up the protective environmental shell in which the spacefarer is enclosed.


    This radio-protective environment could be included in the air envelope, spacesuits, space stations, vehicles both ground and space, and living areas in general.


    This technology would protect the humans species form high rates of mutation, associated genetic diseases and possible evolution into divergent species.

  • Axil: just for my interest, are you pulling our legs with posts like the one above? I normally don't comment, but it seems unkind to some on the site for you to be posting such stuff and then quietly laughing at those who take it seriously?

  • Quote

    For particle physicists whose entire standard model assumes that decay rates cannot be influenced by external factors, the Purcell effect is a puzzle.


    The Purcell effect is the enhancement of a quantum system's spontaneous emission rate by its environment. In the 1940s Edward Mills Purcell discovered the enhancement of spontaneous emission rates of atoms when they are incorporated into a resonant cavity. It has nothing to do with radioactive decay rate and its theory is elaborated well.

  • The Purcell effect is the enhancement of a quantum system's spontaneous emission rate by its environment. In the 1940s Edward Mills Purcell discovered the enhancement of spontaneous emission rates of atoms when they are incorporated into a resonant cavity. It has nothing to do with radioactive decay rate and its theory is elaborated well.


    Just to elaborate. Axil, the reasons rates get enhanced in this way is not some obscure bit of particle physics but instead central to the core ideas of QM. Resonant cavities alter the probabilities because they provide a greater density of final states. It is pure Maths that if there are N ways for A to happen, and N' ways for B to happen, then N >> N' means A is a lot more likely than B.


  • The only link you have given supports my previous post, and has no relation to your statements. Specifically, in a resonant cavity, because of the Purcell effect, decay can be enhanced. Perhaps you'd like to be more precise in the factual claims that you think massive (or even normal) intellects need to explain?


    It might help you if I point out that physics is full of real mysteries; one reason I find it fascinating.


    It is a pity that useful for energy production reactions tend not to be spontaneous gamma emission. Otherwise using the correct dielectric environment would be a great rate of boosting (even of dynamically changing) the power/weight ratio of nuclear power sources as used in space probes. Or maybe there is such a useful reaction? On second thought I think you'd have a problem with energy density since these gamma emissions come from these relatively low energy nuclear transitions, but I have not done the maths.

  • The only link you have given supports my previous post, and has no relation to your statements. Specifically, in a resonant cavity, because of the Purcell effect, decay can be enhanced. Perhaps you'd like to be more precise in the factual claims that you think massive (or even normal) intellects need to explain?


    It might help you if I point out that physics is full of real mysteries; one reason I find it fascinating.


    It is a pity that useful for energy production reactions tend not to be spontaneous gamma emission. Otherwise using the correct dielectric environment would be a great rate of boosting (even of dynamically changing) the power/weight ratio of nuclear power sources as used in space probes. Or maybe there is such a useful reaction? On second thought I think you'd have a problem with energy density since these gamma emissions come from these relatively low energy nuclear transitions, but I have not done the maths.


    I don't see any answers, just bloviation..

  • Why does radioactive decay stop in the LENR reaction?



    Why do only left handed particles decay and right handed particles don't?


    axil : You are confusing facts and ask the wrong questions! Nobody never did prove that "radioactive decay stops in the LENR reaction".


    The second question must be asked in a different way: Why can we only see "left handed particles decay"!...may be all are left handed...

  • axil : You are confusing facts and ask the wrong questions! Nobody never did prove that "radioactive decay stops in the LENR reaction".


    The second question must be asked in a different way: Why can we only see "left handed particles decay"!...may be all are left handed...



    Some attempts at answering. Try for more. Why does radioactive decay be made to increase?

  • Axil,


    Can I suggest you stop classifying the (well understood) Purcell Effect as bloviation and read a few papers (some selected below) on how and why it works? That would answer your repeated questions.


    https://arxiv.org/pdf/0910.3981.pdf


    https://journals.aps.org/prl/a…03/PhysRevLett.112.016401


    https://journals.aps.org/prl/a…03/PhysRevLett.112.016401


    And as for your other statements here, if you provide specific observations (with links to papers giving details) that you think are mysteries and not properly predicted by physics we could all comment.