THIS IS A SUPPORTING PROPOSAL FOR A NEW SUBORBITAL PROGRAM, HELIX (HIGH-ENERGY LIGHT ISOTOPE EXPERIMENT), DESIGNED TO MAKE MEASUREMENTS OF THE ISOTOPIC COMPOSITION OF LIGHT COSMIC RAY NUCLEI FROM ~200 MEV/NUC TO ~10 GEV/NUC. PAST MEASUREMENTS OF THIS KIND HAVE PROVIDED PROFOUND INSIGHTS INTO THE NATURE AND ORIGIN OF COSMIC RAYS, REVEALING, FOR INSTANCE, INFORMATION ON ACCELERATION AND CONFINEMENT TIME SCALES, AND EXPOSING SOME CONSPICUOUS DISCREPANCIES BETWEEN SOLAR AND COSMIC-RAY ABUNDANCES. THE MOST DETAILED INFORMATION CURRENTLY AVAILABLE COMES FROM THE ACE/CRIS MISSION, BUT IS RESTRICTED TO ENERGIES BELOW A FEW 100 MEV/NUC. HELIX AIMS AT EXTENDING THIS ENERGY RANGE BY OVER AN ORDER OF MAGNITUDE, TO ENERGIES WHERE, IN MANY CASES, NO MEASUREMENTS OF ANY KIND EXIST. THE HELIX MEASUREMENTS WILL PROVIDE ESSENTIAL INFORMATION FOR UNDERSTANDING THE PROPAGATION HISTORY OF COSMIC RAYS IN THE GALAXY. THIS IS A CRUCIAL ELEMENT FOR PROPERLY INTERPRETING SEVERAL INTRIGUING ANOMALIES REPORTED IN RECENT COSMIC-RAY MEASUREMENTS, PERTAINING TO THE ENERGY SPECTRA OF PROTONS, HELIUM, AND HEAVIER NUCLEI, AND PERHAPS MOST STRIKINGLY, TO THE ANOMALOUS RISE IN THE POSITRON FRACTION AT HIGHER ENERGY
Posted 12/31/15, 12:00 AM