Muons are in the crosshairs of physicists. And they are for good reason: they are one of your best assets when it comes to finding cracks in physics theory more consistent than all they have produced so far. Finding cracks in the Standard Model is not easy, but some of the experiments carried out at CERN and Fermilab in recent years involving these particles invite scientists to face the future of physics with very healthy optimism.
The muons, which are the true protagonists of this article, are very special. These elementary particles are only produced when high-energy collisions take place, such as those involving cosmic rays, and also in human-caused collisions at particle accelerators. In addition, they are unstable, which causes them to decay rapidly when they originate, disintegrating to give rise to the production of other particles, such as electrons, which are stable, or neutrinos (only the electronic neutrino is stable).
However, its usefulness goes far beyond the realm of theoretical physics. And it is that muons have the ability to intervene in nuclear fusion. In that same nuclear fusion that has been at the center of public conversation for several years, and about which we will talk much more in the future. The one supported by two projects as promising as ITER or IFMIF-DONES. Interestingly, its role in this way of obtaining energy it is very little known outside the realm of research, and, as we are about to see, it is exciting. Fiance.
The perfect nuclear fusion is the one catalyzed by muons.
Before going any further, it is important that we get to know muons a little better. Like electrons, these elementary particles have a negative charge, but, and this is very important, their mass is approximately 207 times greater than that of the electron, which causes them to accelerate more slowly when subjected to the effect of a field. electromagnetic. And also that they emit less braking radiation, which is a form of electromagnetic radiation that is produced due to the deceleration of an electrically charged particle.
Muons belong to a family of particles known as leptons, in which they coexist with the electron, the electron neutrino, the muon neutrino, the tau, and the tau neutrino, and they have another property that is worth noting: they spin. in an orbit that is two hundred times closer of the atomic nucleus than the electron.
Curiously, if we put the two ingredients of nuclear fusion, a deuterium nucleus and a tritium nucleus, in a container together with a muon, the latter will take the place of an electron, but it will be much closer to the proton of the nucleus (remember that deuterium and tritium are isotopes of hydrogen and have a single proton in the nucleus) than the original electron did.
If we place a mixture of deuterium and tritium in a container and introduce a muon, this last particle will cause the fusion of a deuterium nucleus and a tritium nucleus.
Since the muon has a negative charge and that of the proton is positive, its greater proximity to the orbit of the electron causes that the charge of the proton is neutralized, so it is possible that another nearby proton will approach the proton surrounded by the muon. If the charge of the latter has been neutralized and both protons get close enough, it is possible that the strong nuclear interaction takes place and the fusion of both nuclei occurs, with the consequent release of energy.
All this means, simply, that if we put a mixture of deuterium and tritium in a container, and introduce a muon, this last particle will cause the fusion of a deuterium nucleus and a tritium nucleus. A lot of energy will be released, as we have seen, and, furthermore, the muon will not be consumed. In fact, one of these particles can intervene in up to two hundred mergers before disintegrating. But the benefits of muon-catalyzed fusion do not end there.
Muons introduce great advantages, but also enormous challenges.
To fuse deuterium and tritium using a muon as a catalyst, the nuclei of the first two elements do not have to be at least 150 million degrees Celsius, which is the temperature required for nuclear fusion by magnetic confinement to come to fruition. It is enough that they are at a temperature of about 500 degrees Celsius, which is nothing compared to 150 million degrees. In fact, this is why this form of fusion is often referred to as “cold fusion,” even though it isn’t really cold at all.
The muons disintegrate when reaching a figure close to two hundred fusions
Carrying out the fusion without the need to reach a temperature as high as that required by the experimental reactors currently in operation, such as JET, in Oxford (England), or JT-60SA, which is in Naka (Japan), has several advantages.
The most obvious is that the conditions that must be maintained for the merger to take place they are much less demanding. In addition, the energy that is necessary to invest to trigger the reaction is also much more restrained, and to a certain extent the complexity of the installation from a technical point of view is somewhat reduced, although we are still very far from the moment in which the commissioning about to a fusion power reactor is a piece of cake (if it ever becomes one).
As you can see, so far everything looks great. But there are two restrictions important enough for this fusion procedure to be unprofitable from an energy point of view. At least until now. On the one hand, the muons disintegrate when they reach a number close to two hundred fusions.
And, on the other hand, to obtain a muon we need to collide particles and invert in this process approximately two hundred times the energy that we will get as a result of nuclear fusion. Under these conditions, obviously, this process is not profitable from an energy point of view.
The only way to achieve a positive energy balance during this process requires finding a way to keep the muons from decaying after those two hundred or so mergers. And, for the moment, this possibility threatens fundamental physics.
Even so, if someone devises a strategy that puts in our hands the possibility that a muon could intervene in a number of mergers greater than those two hundred, the nuclear fusion induced by these particles it will be profitable. Unfortunately right now this idea has more science fiction than science. But, who knows, experience has taught us that sometimes scientific development has broken down walls that seemed even higher.
Cover image: CERN
