Counting within the Darkish | by Brian Koberlein



20 September 2014

The Alpha Magnetic Spectrometer on the International Space Station.
The Alpha Magnetic Spectrometer on the Worldwide Area Station.

The Alpha Magnetic Spectrometer (AMS) is a particle detector positioned on the Worldwide Area Station. It’s designed to detect excessive vitality particles referred to as cosmic rays, and some time again it made information relating to claims it had detected darkish matter. It hadn’t, however as an alternative had detected an extra of positrons that would possibly be as a consequence of darkish matter. It is also as a consequence of different issues, which is why claiming it had discovered proof of darkish matter was a bit disingenuous. Now the AMS is again with extra knowledge. Regardless of some claims, the brand new outcomes don’t trace at darkish matter any greater than final time, however it’s nonetheless stable work.

Cosmic rays are very excessive vitality particles (sometimes protons) produced by numerous astrophysical phenomena. They have been first detected by their impact when placing Earth’s ambiance, which causes a cascade of particles to be produced. Most cosmic ray astronomy is finished on Earth by taking a look at these particle cascades. Whereas this offers us a good suggestion of the forms of energies cosmic rays can have, it doesn’t inform us a lot in regards to the forms of particles that make up cosmic rays. We’ve identified for some time that they’re largely protons, however they may also be electrons and positrons, amongst different issues.

The variation of positron counts with energy.
M. Aguilar et al
The variation of positron counts with vitality.

As a result of the AMS is on the area station, it could actually detect these cosmic rays straight, so it could actually distinguish between protons, electrons, positrons and the like. By wanting on the ratio of protons to electrons, and positrons to electrons, we will begin to perceive the forms of mechanisms that produces cosmic rays. Because the final media debacle, the AMS has continued to assemble extra observations, and this new work supplies an replace of the newest outcomes.

These new outcomes principally simply refine the sooner findings. Like final time, the ratio of positrons to electrons inside cosmic rays will increase at larger energies. That is attention-grabbing as a result of normal collisions of excessive vitality particles with interstellar matter ought to produce a lower of positrons at larger energies. This implies that there are different mechanisms occurring.

One among these mechanisms is theoretically darkish matter, however this new outcome shouldn’t be taken as proof of darkish matter. Black holes, pulsars, white dwarfs, and so on. might all account for the same rising ratio. The large outcome right here just isn’t that it’s proof of darkish matter, however merely the truth that we’ve got an correct particle rely. We’ve truly suspected that the fraction of positrons would enhance at larger energies, and now we even have the proof to again up that suspicion.

The following step shall be to see what particulars from these cosmic ray counts we will collect, so we will use the outcomes to slender down potential sources. There are loads of very excessive vitality interactions occurring in deep area, and cosmic ray particle counts ought to assist us higher perceive them.

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