Cosmic count exceeds expectation: Alpha Magnetic Spectrometer on ISS reveals surplus of cosmic rays

Cosmic rays confound scientists as soon as once more. The newest evaluation of knowledge collected by the Alpha Magnetic Spectrometer (AMS) on board the Worldwide House Station has revealed a stunning surplus of cosmic rays fabricated from deuterons—atomic nuclei made up of a proton and a neutron.

The discovering, described in a paper revealed in Bodily Evaluation Letters, provides to the rising checklist of surprising results from the space-based detector, which was assembled at CERN and has detected greater than 238 billion cosmic rays of particles of varied sorts because it began taking knowledge in 2011.

Cosmic-ray particles fall into two predominant courses: main and secondary. Main cosmic rays are fashioned in cosmic sources equivalent to supernova explosions, whereas secondary cosmic rays are produced in interactions between main cosmic rays and the interstellar medium.

In its newest examine, the AMS collaboration investigated knowledge from 21 million cosmic deuterons detected by AMS from Might 2011 to April 2021. Analyzing how the quantity, or “flux,” of deuterons varies with rigidity, that’s, particle momentum over electrical cost, the AMS workforce discovered stunning options.

Deuterons are thought to type in the identical means as helium-3 nuclei, in collisions between main helium-4 nuclei and different nuclei within the interstellar medium. If that’s certainly the case, the deuteron-to-helium-4 flux ratio must be just like the helium-3-to-helium-4 flux ratio.

However this isn’t what AMS sees. In contrast, the AMS knowledge exhibits that these ratios are notably completely different above a rigidity of 4.5 gigavolts (GV), with the deuteron-to-helium-4 ratio falling much less steeply with rigidity than the helium-3-to-helium-4 ratio. As well as, and once more defying expectations, above a rigidity of 13 GV the info exhibits that the deuteron flux is sort of an identical to that of protons, that are main cosmic rays.

To place it merely, AMS has discovered extra deuterons than anticipated from collisions between main helium-4 nuclei and the interstellar medium.

“Measurement of deuterons is kind of troublesome due to the massive cosmic proton background,” says AMS spokesperson Samuel Ting. “Our surprising outcomes proceed to indicate how little we find out about cosmic rays. With the approaching upgrade of AMS to extend its acceptance by 300%, AMS will be capable to measure all of the charged cosmic rays to 1 p.c accuracy and supply an experimental foundation for the event of an correct cosmic-ray concept.”