Cosmic-ray Heavy Nuclei Spectra Using the ISS-CREAM Instrument

International audienceCosmic 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

Measurement of High-energy Cosmic-Ray Proton Spectrum from the ISS-CREAM Experiment

International audienceThe Cosmic Ray Energetics And Mass for the International Space Station (ISS-CREAM) experiment successfully recorded data for 539 days from 2017 August to 2019 February. We report the energy spectrum of cosmic-ray protons from the ISS-CREAM experiment at energies from 1.60 × 10$^{3}$ to 6.55 × 10$^{5}$ GeV. The measured spectrum deviates from a single power law. A smoothly broken power-law fit to the data, including statistical and systematic uncertainties, shows the spectral index change at 9.0 × 10$^{3}$ GeV from 2.57 ± 0.03 to 2.82 ± 0.02 with a significance of greater than 3σ. This bump-like structure is consistent with a spectral softening recently reported by the balloon-borne CREAM, DAMPE, and NUCLEON, but ISS-CREAM extends measurements to higher energies

e/p Separation Study Using the ISS-CREAM Top and Bottom Counting Detectors

International audienceCosmic Ray Energetics And Mass for the International Space Station (ISS-CREAM) is an experiment for studying the origin, acceleration, and propagation mechanisms of high-energy cosmic rays. The ISS-CREAM instrument was launched on the 14th of August 2017 to the ISS aboard the SpaceX-12 Dragon spacecraft. The Top and Bottom Counting Detectors (TCD/BCD) are parts of the ISS-CREAM instrument and designed for studying electron and gamma-ray physics. The TCD/BCD each consist of an array of 20 × 20 photodiodes on a plastic scintillator. The TCD/BCD can separate electrons from protons by using the difference between the shapes of electromagnetic and hadronic showers in the high energy region. The Boosted Decision Tree (BDT) method, which is a deep learning method, is used in this separation study. We will present results of the electron/proton separation study and rejection power in various energy ranges

On-orbit performance of the ISS-CREAM SCD

International audienceThe Cosmic Ray Energetic And Mass for the International Space Station (ISS-CREAM) experiment is designed for precision measurements of energy spectra and elemental composition of cosmic rays. It was launched and installed on the ISS in August 2017. The Silicon Charge Detector (SCD), placed at the top of the ISS-CREAM payload, consists of 4 layers with a total of 10,752 silicon pixels which have 1.37 × 1.57 cm^2 size each. Each layer is arranged in such a fashion that its active detection area of 78 × 74 cm^2 is free of any dead area. The SCD 4-layer configuration was chosen to achieve the best precision in measuring the charge of cosmic rays from proton to iron nuclei with a charge resolution of 0.1 − 0.3e. We will present its on-orbit performance and operation status on the ISS since the launch

ISS-CREAM Flight Operation

International audienceThe 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

On-orbit Performance of the ISS-CREAM Calorimeter

International audienceCosmic Ray Energetics And Mass for the International Space Station (ISS-CREAM) experi-ment is designed to study the composition and energy spectra of cosmic-ray particles from 10^12 to 10^15 eV. ISS-CREAM was launched and deployed to the ISS in August 2017. The ISS-CREAM payload employs a Silicon Charge Detector for charge measurements, Top and Bot-tom Counting Detector for electron-hadron separation and a low-energy trigger, a Boronated Scintillator Detector for additional electron-hadron separation, and a Calorimeter (CAL) for en-ergy measurements and a high-energy trigger. The CAL is constructed of 20 layers of tungsten plates interleaved with scintillating fiber ribbons read out by hybrid-photodiodes (HPDs) and densified carbon targets. Each CAL layer is made of 3.5 mm (1 X_0) thick tungsten plates alter-nating with fifty 0.5 mm thick and 1 cm wide scintillating fiber ribbons. Consecutive layers of fiber ribbons are installed orthogonal to each other. Energy deposition in the CAL determines the particle energy and provides tracking information to determine which segment(s) of the charge detectors to use for the charge measurement. Tracking for showers is accomplished by extrapolating each shower axis back to the charge detectors. The performance of the ISS-CREAM CAL during flight is presented

Cosmic-Ray Elemental Spectra Measured with ISS-CREAM

International audienceThe Cosmic Ray Energetics And Mass experiment for the International Space Station (ISS-CREAM) is a direct cosmic-ray detection experiment deployed on the ISS in August 2017. It aims to reveal the sources, acceleration processes, and propagation of cosmic rays by observing individual elemental spectra at energies in the TeV-PeV range. ISS-CREAM consists of multiple complementary particle detectors. This work utilizes the Silicon Charge Detector (SCD) to measure cosmic-ray charges from protons to iron nuclei with a resolution of 0.1-0.3e, and the calorimeter (CAL) to determine the cosmic-ray track and measure its energy by sampling the shower energy deposit of secondary particles. With more than 1-year of observations, we analyzed cosmic-ray spectra of various prominent species such as protons, helium, carbon and oxygen nuclei. We will report preliminary elemental spectra of cosmic rays for energies greater than about 10 TeV

Track Reconstruction for ISS-CREAM Resulting in Improved Energy and Charge Resolutions

International audienceCosmic Ray Energetics And Mass for the International Space Station (ISS-CREAM) has taken 1.5 years of direct measurements of high-energy cosmic ray (HECR) particles for energies from 10$^{12}$ to 10$^{15}$ eV. HECR particle identification is significantly improved by tracking particle-detector interactions from the calorimeter (CAL) back to the Silicon Charge Detector (SCD) for charge determination. A track finding algorithm resistant to such issues as particle multiplicity, backscatter, and electronic noise will be outlined. Also, shown is the energy resolution improvement, and the resulting all particle spectrum, provided by ensuring good particle tracks. This allows ISS-CREAM to investigate how the energy distributions evolve, for protons all the way to iron nuclei, and will provide important information for models of galactic sources and HECR propagation

Monte Carlo Simulations of the ISS-CREAM Instrument

International audienceCosmic 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

Cosmic Ray Energetics And Mass for the International Space Station (ISS-CREAM)

International audienceThe ISS-CREAM payload was launched on the SpaceX-12 Commercial Resupply Service mission to the International Space Station (ISS) from NASA’s Kennedy Space Center on August 14, 2017. It was successfully installed and activated on the ISS Japanese Experiment Module Exposed Facility as an attached payload on August 22, 2017. The ISS-CREAM instrument is configured with complementary particle detectors capable of measuring elemental spectra for Z = 1 - 26 nuclei in the energy range ~10^12 – 10^15 eV; as well as electrons at multi-TeV energies. The four layers of its finely segmented Silicon Charge Detectors provide precise charge measurements, and its ionization Calorimeter provides energy measurements. In addition, scintillator-based Top and Bottom Counting Detectors and a Boronated Scintillator Detector distinguish electrons from nuclei. The goal is to understand cosmic ray origin, acceleration and propagation by extending direct measurements of cosmic rays to the highest practical energy. On-orbit performance of the instrument and preliminary results from the ongoing analysis are presented