giovedì 16 aprile 2015

AMS confirms also PAMELA data on protons and helium

In these days, AMS is presenting new results on galactic cosmic  particles and antiparticles.
Most interesting are the new results on protons and helium, which confirm the PAMELA  data (published on Science in 2011) on proton and helium, verifying the existence of a change in the spectral index of proton and helium above 240 GV.  This change in the spectral index is seen by AMS also in heavier nuclei, confirming also the CREAM balloon results.
As for electons and positrons, thanks to its size, the Space Station based particle spectrometer extends these measurements to higher energy.
The confirmation is very important because is shows that - as hypothesized in our Science paper - even at relatively low energies there is a new astrophysical component accelerating cosmic rays. Furthermore the different spectral index of proton and helium shows that even these particles, the most common in cosmic rays, undergo different acceleration mechanisms in the Galaxy
Proton data of AMS compared with previous experiments. PAMELA is in blue 
These data are substantially different from those presented by AMS in ICRC 2013 that showed no change in spectral index (and theat puzzled our colleagues in theory), so the current new agreement of AMS with PAMELA is  even more welcome.
Congratulations to our AMS friends for the excellent work!

For reference, below are the original AMS02 ICRC data, showing no change in the spctral index: