It appears that this is using coincidence detection to locate objects, surface boundaries, etc. relative to a fixed array of sensors. In order to use this as an underwater location sensor, you'd have to have some communications channel that could time the arrival of muons and correlate them with detections at known fixed locations. I fail to see how this would provide global position.
The referenced paper[1] does not address clock distribution, nor the distribution of detection data for correlation into position information.
Unless the researchers have a reliable, atomically timed source of cosmic ray pulses that can be known a-priori, I fail to see how this could be used to determine global location, except post facto, when all data could be correlated, and the previous locations determined.
Thus, I fail to see this as a viable candidate for replacing the global positioning system, at this time.
It does address clock distribution, though the distribution method is sneakernet, in other words "synchronise clocks at one location, then walk away and come back with it".
For some reason I'm struggling to understand both the paper and the Ars writeup. It must be the *same muon* they're detecting passing through both the stationary reference detector and the mobile one? Which generates multiple photons along its straight-line path? That must be why the nanosecond-precision clocks are so critical—to find the true coincidences and exclude everything else. And: the version with wires can navigate in real-time... but, the wireless version can only "navigate" retrospectively, because you need to link the receiver and reference to figure anything out (?). There's no (?) version of this method that lets you navigate outside of communications range, during the interval you are out of communications range.
Yes, it's the same muon leaving a signal in the reference detector as in the mobile platform. Their example applications of guiding robots underground all allow for instrumenting the surface. It's not for navigating in the open ocean, but it could be an upgrade over radio based methods of guiding directional drilling heads and things like that.
Late update: I'm now convinced it's a single-muon thing, because of the paper's discussion about the distance between, and *solid angle* subtended by, the two detectors (eq. 2). If they go too far apart, the rate of individual muons that coincidentally hit both detectors drops to unusably low levels (eq. 3, the 1/D² dependence). If it were instead a "they're detecting secondary particles from the same cosmic shower" like someone proposed, this part would be totally different.
The principle is "Multiple Coulomb Scattering", and there is a nice brief overview of that in <https://arxiv.org/abs/2212.04947> notably in fig. 1 and fig. 2. There are even more gory details at <https://sci-hub.se/https://doi.org/10.1016/j.nima.2015.06.05...> (s c y h o b link to Anghel et al 2015, a Canadian muon tomography experiment interested in detecting high atomic number elements for e.g. anti-proliferation/anti-smuggling purposes).
Having not read the article, nor really the Ars piece either, let me hand wave by saying that cosmic muons are produced as secondary particles emitted from a high energy collision of a primary extraterrestrial particle that collides with particles in the stratosphere (around 30km up).
This shower of muons is “boosted” by kinetic energy of the primary particle. That means they have a lifetime that is longer than at rest when observed from Earth, but relevant to this method, they are also temporally correlated in such a way that by determining the time of arrival at multiple stations, the origin of the primary interaction can be determined - and more importantly, the timings between the stations can be deduced. Having fixed stations, and an unfixed one, means you can infer the latter’s position through geometric analysis.
To actually answer you question, it is not the same muon hitting all stations, but a spray of highly correlated muons originating from the same interaction point.
Philosophically, muons are considered elementary particles, and are as such considered identical particles. Though, that has no effect in this situation.
The green ray is not wrong because of multiple muons, but because of mutiple Coulomb scattering (MCS) within the scintillators. There is a brief overview of MCS in a muon tomography context starting at the top of the second column on the first page of <https://arxiv.org/abs/2212.04947>. Figures 1 and 2 therein show the trajectory of a single muon experiencing MCS within a plastic scintillator.
Please don't read the article and instead just guess what they did. You are in fact entirely wrong: they use that the same muon passing trough two detectors, something that happens by chance, and you can identify by knowing the geometrical distance between the two detectors and convert to a very narrow time window during which you accept signals.
Looks like they're different. OP is using muons (Cosmic rays) and the Royal Navy one is using some quantic properties to track movements more precisely (fancier dead reckoning)
In order for this to be a global system, you'd have to be able measure muon coincidence across thousands of miles, which isn't possible, as muon showers are far more localized.
Systems like Loran-C used to offer this for terrestrial, radio based navigation at sea.
Not at all. This solves a somewhat different problem: determining your position relative to a number of nearby reference stations (on the order of tens of meters away).
The limiting factor is that you have to wait for enough muons to pass through both your mobile detector and your reference stations. The farther apart they are, the lower the odds of this happening by random chance, so the longer you have to wait, with the fix time increasing proportional to distance^2. You also need a very accurate shared time reference between the reference detectors and the receiver; for this experiment, that was provided by piggybacking on GPS time.
The detector also needs to be fairly physically large. The Ars Technica article talks about the potential for miniaturization, but I believe this is a distortion or misunderstanding of the research. It's true that the researchers anticipate being able to miniaturize and improve some of the electronics of the detector, primarily through the use of chip-scale atomic clocks rather than OCXOs. But as the paper discusses (pg. 13), you can't really miniaturize the muon detector itself; it needs to be physically large because the muon detection rate is directly proportional to its area. For this experiment, 100x100x2 cm plastic scintillators were used.
So if I understood that properly, the moment an underground/sea vehicle changes its angle wrt to the parent station, its chances of seeing the same muon drop rapidly (0.98 cos(alpha) + 0.02).
The referenced paper[1] does not address clock distribution, nor the distribution of detection data for correlation into position information.
Unless the researchers have a reliable, atomically timed source of cosmic ray pulses that can be known a-priori, I fail to see how this could be used to determine global location, except post facto, when all data could be correlated, and the previous locations determined.
Thus, I fail to see this as a viable candidate for replacing the global positioning system, at this time.
[1] https://www.sciencedirect.com/science/article/pii/S258900422...