Research group unveils properties of cosmic-ray sulfur and the composition of other primary cosmic rays

Charged cosmic rays, high-energy clusters of particles transferring by way of space, have been first described in 1912 by physicist Victor Hess. Since their discovery, they’ve been the subject of quite a few astrophysics research geared toward higher understanding their origin, acceleration and propagation by way of space, utilizing satellite information or different experimental strategies.

The Alpha Magnetic Spectrometer (AMS) collaboration, a big analysis group analyzing information collected by a big magnetic spectrometer in space, just lately gathered new perception concerning the properties and composition of particular kinds of cosmic rays. In a brand new paper, printed in Bodily Assessment Letters (PRL), they particularly unveiled the composition of major cosmic-ray carbon, neon, and magnesium, together with the composition and properties of cosmic-ray sulfur.

“Pioneering experiments learning cosmic rays have sometimes an error of 30% to 50% and principally on the kinetic vitality under 50 Giga electron-volts per nucleon,” Samuel Ting, spokesperson for the AMS Collaboration, informed Phys.org. “These massive error measurements present necessary info that agrees with many theoretical fashions. The Alpha Magnetic Spectrometer experiment on the Worldwide Area Station supplies p.c accuracy measurements of elementary particles (electrons, positrons, protons, and antiprotons) and all components of the periodic desk as much as kinetic vitality of greater than 1,000 Giga electron-volts per nucleon.”

Among the current measurements collected by the AMS detector have been troublesome to clarify utilizing current theoretical physics fashions. As an example, by measuring the rigidity (i.e., momentum/cost) of all charged particles within the rays, the AMS detector gathered information shedding new mild on the properties of two totally different sorts of charged cosmic rays, which the researchers dubbed major and secondary rays.

“Main cosmic rays (e.g., He, C, O, Ne, Mg, Si, S, Fe, …) nuclei are synthesized in stars and accelerated at astrophysical sources like supernovae, and secondary cosmic rays (e.g., Li, Be, B, F, …) nuclei are produced within the interactions of the first cosmic ray with the interstellar media,” Ting defined. “Our current work featured in PRL was impressed by our discovery of distinctive properties of cosmic rays in two earlier publications.”

In a previous paper, the AMS Collaboration confirmed that major cosmic-ray fluxes containing Ne, Mg and Si had an equivalent rigidity dependence above 86.5 Giga volts, which differed considerably from the rigidity dependence of major cosmic rays containing He, C, O, and Fe particles. This means that major cosmic rays might be divided in a minimum of two sub-classes, which the staff dubbed Ne-Mg-Si and He-C- O-Fe.

“To this point, little is understood concerning the properties of the sulfur cosmic rays,” Ting mentioned. “Precision research specializing in the properties of the cosmic sulfur, resembling our new work, might present new insights into the first cosmic rays, serving to us to unveil what number of lessons of major cosmic rays exist.”

In another previous work, Ting and his collaborators discovered proof suggesting that N, Na and Al cosmic rays are mixtures of major and secondary cosmic rays. They then exactly measured the fluxes of those cosmic rays over a large rigidity vary (i.e., from just a few Giga volts to Tera volts) and analyzed their spectrum properties, to find out their distinctive major and secondary parts.

“As an example, the Na/Si and Al/Si abundance ratios on the supply have been measured immediately as 0.036±0.003 and 0.103±0.004, respectively,” Ting mentioned. “These measurements are impartial of cosmic ray fashions. In our present publication we prolonged this methodology to measure the first and secondary compositions of C, Ne, Mg, and S, that are historically assumed to be major cosmic rays. Unexpectedly, we discovered that these components all have sizeable secondary contributions from collision of heavier cosmic rays with the interstellar media.”

The AMS depends on a extremely exact magnetic spectrometer that’s usually used to conduct experiments on Earth, as an example aiding the seek for elementary particles utilizing accelerators. It’s comprised of six detecting components that independently accumulate information concerning the cost, mass, momentum and vitality of elementary particles and nuclei.

AMS is at the moment the one magnetic spectrometer located in space, with researchers on Earth intently and constantly monitoring the functioning of every of its six components to make sure that it operates reliably. Earlier than it was despatched to space, particularly to the Worldwide Area Station, in 2011, the spectrometer was rigorously calibrated utilizing totally different CERN particle accelerators.

“To make sure the accuracy and reliability of the outcomes the uncooked information have been analyzed independently by two to 4 worldwide analysis teams,” Ting mentioned. “By analyzing the primary 10 years of the AMS information, i.e., about 200 billion cosmic rays, we noticed that above 90 Giga volts the rigidity dependence of sulfur flux in cosmic rays is equivalent to the rigidity dependence of the Ne-Mg-Si fluxes, which is totally different from the He-C-O-Fe fluxes rigidity dependence. This reveals that S, unexpectedly, belongs to the Ne-Mg-Si class of major cosmic rays.”

Analyzing information associated to 200 billion cosmic rays passing by way of six totally different detectors was a time-consuming and arduous activity. Finally, the accuracy of the info was verified and cross-checked by 4 impartial analysis groups situated in Italy, Switzerland, China and the US.

“We additionally discovered that the standard major cosmic rays S, Ne, Mg, and C all have sizeable secondary parts. Sulfur, along with C, Ne, and Mg cosmic nuclei all might be offered as a sum of major part (earlier than propagation in Milky Way) and secondary part (throughout and after propagation),” Ting mentioned, “The abundance ratio on the cosmic ray supply for S/Si is 0.167±0.006, for Ne/Si is 0.833±0.025, for Mg/Si is 0.994±0.029, and for C/O is 0.836±0.025. These direct measurements are impartial of cosmic ray fashions.”

Notably, the AMS Collaboration was the primary to precisely measure the flux of S within the cosmos from just a few Giga volts to Tera volts. Their findings enormously contribute to the understanding of cosmic rays, their composition and traits.

The analyses carried out by the AMS collaboration finally recommend that the first and secondary contributions of major of S, C, Ne and Mg cosmic-ray fluxes are markedly totally different to these of N, Na and Al fluxes. Their findings, none of which was predicted by current cosmic ray fashions, might collectively assist to raised perceive the nucleosynthesis in stars in addition to the origin and propagation of cosmic rays.

“AMS will now proceed precision research of the cosmic components,” Ting added. “We’re at the moment upgrading our detector by rising its acceptance by 300%. By 2030, we are going to discover the properties of the remaining heavy cosmic ray components, marked in white. Thus, by 2030 we are going to present correct and complete info on cosmic ray origin and propagation. This may uncover the mysteries of cosmic rays, resembling the place and the way are they created, or how they attain us. In our subsequent works, we plan to review the origin of the dark matter by precision measurements of electrons, positrons, antiprotons, and antideuterons. By 2030, our research of positron, electron, antiproton, and antideuteron spectra along with the research of the positron anisotropy will present an evidence of the present sudden AMS outcomes.”

Whereas analyzing AMS information, Ting and his collaborators have additionally noticed a number of particles that might be viable heavy antimatter candidates, together with antihelium. They thus plan to additionally proceed trying to find extra of those particles, notably anticarbon and antioxygen. Concurrently, they’re analyzing the day by day flux variations of all of the cosmic rays within the heliosphere over each 11 years and 22 years solar cycles, which might yield different attention-grabbing discoveries.

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