BEXCO - Room A(101/102)
[CRD138] Ultra-Heavy GCR measurements beyond SuperTIGER: HNX and TIGERISS
Ultra-heavy galactic cosmic rays (UHGCR) with Z≥30, above the limits of nuclear fusion in stars, are of particular interest to astrophysics in probing the chemical composition of the galaxy and its origin and understanding the dynamics of high energy events like binary neutron star mergers and supernova explosions. Despite the discovery of cosmic-rays over 100 years ago, the individual elemental abundances of UHGCRs are poorly measured due to their extremely low fluxes. We discuss in this paper two instruments, HNX and TIGERISS, being developed to measure these nuclei with high statistics for the first time. The Heavy Nuclei eXplorer (HNX) is a new instrument proposed as a NASA Small Explorer (SMEX) by NASA Goddard Space Flight Center, University of California, Berkeley, Washington University in St. Louis, the Jet Propulsion Laboratory, and the University of Minnesota. HNX will investigate the nature of the reservoirs of nuclei at the cosmic-ray sources, the mechanisms by which nuclei are removed from the reservoirs and injected into the cosmic accelerators, and the acceleration mechanism. HNX will measure, for the first time, the abundance of every individual element in the periodic table from carbon through the actinides, providing the first measurement of many of these elements. Several thousand ultra-heavy galactic cosmic ray (UHGCR) nuclei with atomic number Z≥30 will be recorded, including about 50 actinides. To measure UHGCR with unprecedented statistics and individual element resolution over its full measurement range, HNX will use two large instruments, the Extremely-heavy Cosmic-ray Composition Observer (ECCO) using sophisticated glass detectors and the Cosmic-ray Trans-Iron Galactic Element Recorder (CosmicTIGER) using electronic detectors evolved from SuperTIGER (Super Trans-Iron Galactic Element Recorder). HNX will be accommodated in the SpaceX DragonLab orbiting laboratory that will also return it to Earth for post-flight processing of the ECCO detectors. With the additions of Pennsylvania State University and Northern Kentucky University, we are also developing the Trans-Iron Galactic Element Recorder for the ISS (TIGERISS), an ISS-attached instrument based on SuperTIGER and CosmicTIGER and benefiting from the experience gained by the NASA Wallops Flight Facility (WFF) in developing the ISS accommodation for ISS-CREAM. TIGERISS will measure the abundances of every element from He to Pb, enabling sensitive tests of the relative importance of R and S neutron capture processes and binary neutron star mergers to the nucleosyntheis of UHGCR. The scientific motivations of HNX and TIGERISS and details of the planned missions and instruments will be discussed. Tests of HNX/TIGERISS detectors at CERN will be reported in a paper by John F. Krizmanic at this conference.