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Cosmic Ray Energetics And Mass for the International Space Station (ISS-CREAM) was designed to study high-energy cosmic rays up to PeV and recorded data from August 22nd, 2017 to February 12th, 2019 on the ISS. In this analysis, the Silicon Charge Detector (SCD), CALorimeter (CAL), and Top and Bottom Counting Detectors (TCD/BCD) are used. The SCD is composed of four layers and provides the measurement of cosmic-ray charges with a resolution of $\sim$0.2e. The CAL comprises 20 interleaved tungsten plates and scintillators, measures the incident cosmic-ray particles' energies, and provides a high energy trigger. The TCD/BCDs consist of photodiode arrays and plastic scintillators and provide a low-energy trigger. In this analysis, the SCD top layer is used for charge determination. Here, we present the heavy nuclei analysis using the ISS-CREAM instrument.

One of the consequences of having a high-density calorimeter as part of an experiment is a large number of secondary shower particles generated in the calorimeter -- some of which scatter back up towards the charge measurement devices. This so-called "backscatter effect" can interfere severely with accurate charge measurement of the primary nucleus, especially at high energies, as the number of backscattered particles increases with the incident energy. In this analysis, we study the effect of backscattered particles on particle identification by simulating the ISS-CREAM instrument model detector response using the GEANT3 simulation package [1] with the FLUKA hadronic model [2]. Our study shows the importance of the fine segmentation of charge detectors above the calorimeter. It can minimize backscattered particle contamination in the same charge detector segment as the incident particle to avoid its charge misidentification. We present simulation results regarding charge measurements, including the tracking resolution, backscattering effects, and charge determination efficiency.

The Cosmic Ray Energetics And Mass for the International Space Station (ISS-CREAM) experiment successfully recorded the data for about 539 days from August 2017 to February 2019. In this talk, we report the measurement of the cosmic-ray proton energy spectrum from the ISS-CREAM experiment in the energy range of 2.5 TeV - 650 TeV. For the analysis, we used the silicon charge detector (SCD) placed at the top of the ISS-CREAM payload to identify the incoming cosmic-ray charge. The SCD is finely segmented to minimize charge misidentification due to backscatter effects. The four-layer SCD consists of 10,752 silicon pixels, each of which is 1.37×1.57×0.05 cm^3 in size. The calorimeter (CAL) consists of 20 layers of tungsten/scintillating fibers preceded by carbon targets. It provided cosmic-ray tracking, energy determination, and the high-energy trigger. The Top and Bottom Counting detectors (T/BCD) are above and below the CAL, respectively, and provided the low energy trigger. Each T/BCD is composed of an array of 20×20 photodiodes on plastic scintillators. The measured proton spectral index of 2.67±0.02 between 2.5 and 12.5 TeV is consistent with prior CREAM measurements. The spectrum softens above∼10 TeV consistent with the bump-like structure as reported by CREAM-I+III, DAMPE, and NUCLEON, but ISS-CREAM extends measurements to higher energies than those prior measurement

International audience; The Cosmic Ray Energetics And Mass experiment for the International Space Station (ISS-CREAM) is designed and built to measure the elemental energy spectra of cosmic-ray particles (1 ≤ Z ≤ 26) and electrons. It measures the energy of incident cosmic rays from 10^12 to 10^15 eV. ISS-CREAM was launched and deployed to the ISS in August 2017. The Science Operations Center (SOC) at the University of Maryland has been operating the payload on the Interna-tional Space Station (ISS) in coordination with the Payload Operations Integration Center (POIC) at NASA’s Marshall Space Flight Center. The SOC has been responsible for sending commands to and receiving data from the Science Flight Computer (SFC) on board ISS-CREAM. The ISS-CREAM data taking program interfaces with the POIC using the Telescience Resources Kit through the Software Toolkit for Ethernet Lab-Like Architecture developed by the Boeing Company. The command uplink and data downlink have been through the Track-ing and Data Relay Satellite System. We present the ISS-CREAM flight operations including ISS communications, SFC performance, etc.

International audience; Cosmic Ray Energetics and Mass for the International Space Station (ISS-CREAM) is designed to directly measure the energy spectra of high-energy cosmic rays, encompassing proton to iron nuclei, over the energy range from 1012 to 1015 eV [1]. The capability to measure an extended energy range enables us to probe the origin and acceleration mechanisms of cosmic rays. The ISS-CREAM instrument is configured with the balloon-borne CREAM calorimeter (CAL) for energy measurements and four layers of a finely segmented Silicon Charge Detector (SCD) for charge measurements. In addition, two new compact detectors have been developed for electron/proton separation: Top and Bottom scintillator-based counting detectors (TCD/BCD) and a boronated scintillator detector (BSD). Simulations use the GEANT3 package [2] with the FLUKA hadronic model [3]. An isotropic event generator was developed for the ISS-CREAM geometry with particles incident from the upper hemisphere. We will present simulation results regarding ISS-CREAM performance, including trigger rates, energy resolution, energy response, tracking resolution, charge efficiency, etc.