First results of a cosmic-ray electron and positron spectrum from 10 GeV to 3 TeV is presented based upon observations with the CALET instrument on the International Space Station starting in ...October, 2015. Nearly a half million electron and positron events are included in the analysis. CALET is an all-calorimetric instrument with total vertical thickness of 30 X_{0} and a fine imaging capability designed to achieve a large proton rejection and excellent energy resolution well into the TeV energy region. The observed energy spectrum over 30 GeV can be fit with a single power law with a spectral index of -3.152±0.016 (stat+syst). Possible structure observed above 100 GeV requires further investigation with increased statistics and refined data analysis.
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CMK, CTK, FMFMET, IJS, NUK, PNG, UM
In this paper, we present the measurement of the energy spectra of carbon and oxygen in cosmic rays based on observations with the Calorimetric Electron Telescope on the International Space Station ...from October 2015 to October 2019. Analysis, including the detailed assessment of systematic uncertainties, and results are reported. The energy spectra are measured in kinetic energy per nucleon from 10 GeV/n to 2.2 TeV/n with an all-calorimetric instrument with a total thickness corresponding to 1.3 nuclear interaction length. The observed carbon and oxygen fluxes show a spectral index change of ∼0.15 around 200 GeV/n established with a significance > 3σ. They have the same energy dependence with a constant C/O flux ratio 0.911 ± 0.006 above 25 GeV/n. The spectral hardening is consistent with that measured by AMS-02, but the absolute normalization of the flux is about 27% lower, though in agreement with observations from previous experiments including the PAMELA spectrometer and the calorimetric balloon-borne experiment CREAM.
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The CALorimetric Electron Telescope CALET is a space instrument designed to carry out precision measurements of high energy cosmic-rays on the JEM-EF external platform on the International Space ...Station, where it has been collecting science data continuously since mid October 2015. In addition to its primary goal of identifying nearby sources of high-energy electrons and possible signatures of dark matter in the electron spectrum, CALET is carrying out extensive measurements of the energy spectra, relative abundances and secondary-to-primary ratios of elements from proton to iron, and even above (up to Z = 40), studying the details of galactic particle propagation and acceleration. An overview of CALET based on the data taken during the first three years of observations is presented, including a direct measurement of the electron+positron energy spectrum from 11 GeV to 4.8 TeV. The proton spectrum has been measured from 50 GeV to 10 TeV covering, for the first time with a single space-borne instrument, the whole energy interval previously investigated in separate sub-ranges by magnetic spectrometers and calorimetric instruments. Preliminary spectra of cosmic-ray nuclei are also presented, together with gamma-ray observations and searches for an e.m. counterpart of LIGO/Virgo GW events.
Particle detector prototypes, equipped with Silicon PhotoMultipliers (SiPMs) and readout by dedicated front-end electronics, were tested with beams of fully ionized nuclei from boron (Z=5) to nickel ...(Z=28) with a kinetic energy ∼1GeV/amu, at the Fragment Separator (FRS) of the GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt. The tested instruments included prototypes of Cherenkov and scintillation hodoscopes designed for cosmic-ray experiments in space or in the upper atmosphere. In this paper, we summarize the results from the analysis of the beam tests data and of dedicated laboratory tests to characterize the response of the photosensors, the front-end electronics and the performance of the prototypal detectors.
► Performance of detectors readout by Silicon Photomultipliers. ► Saturation of SiPM response with heavy nuclei. ► Charge measurement of fully stripped high Z nuclei with scintillators and Cherenkov radiators.
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The CALET (CALorimetric Electron Telescope) space experiment, which is currently conducting direct cosmic-ray observations onboard the International Space Station (ISS), is an all-calorimetric ...instrument optimized for cosmic-ray electron measurements with capability to measure hadrons and gamma-rays. Since the start of observation in October 2015, smooth and continuous operations have taken place. In this paper, we will give a brief summary of the CALET observations ranging from charged cosmic rays, gamma-rays, to space weather, while focusing on the energy spectra of electrons and protons.
We present measurements of the relative abundances of cosmic-ray nuclei in the energy range of 500-3980 GeV/nucleon from the second flight of the Cosmic Ray Energetics And Mass balloon-borne ...experiment. Particle energy was determined using a sampling tungsten/scintillating-fiber calorimeter, while particle charge was identified precisely with a dual-layer silicon charge detector installed for this flight. The resulting element ratios C/O, N/O, Ne/O, Mg/O, Si/O, and Fe/O at the top of atmosphere are 0.919 {+-} 0.123{sup stat} {+-} 0.030{sup syst}, 0.076 {+-} 0.019{sup stat} {+-} 0.013{sup syst}, 0.115 {+-} 0.031{sup stat} {+-} 0.004{sup syst}, 0.153 {+-} 0.039{sup stat} {+-} 0.005{sup syst}, 0.180 {+-} 0.045{sup stat} {+-} 0.006{sup syst}, and 0.139 {+-} 0.043{sup stat} {+-} 0.005{sup syst}, respectively, which agree with measurements at lower energies. The source abundance of N/O is found to be 0.054 {+-} 0.013{sup stat} {+-} 0.009{sup syst+0.010esc} {sub -0.017}. The cosmic-ray source abundances are compared to local Galactic (LG) abundances as a function of first ionization potential and as a function of condensation temperature. At high energies the trend that the cosmic-ray source abundances at large ionization potential or low condensation temperature are suppressed compared to their LG abundances continues. Therefore, the injection mechanism must be the same at TeV/nucleon energies as at the lower energies measured by HEAO-3, CRN, and TRACER. Furthermore, the cosmic-ray source abundances are compared to a mixture of 80% solar system abundances and 20% massive stellar outflow (MSO) as a function of atomic mass. The good agreement with TIGER measurements at lower energies confirms the existence of a substantial fraction of MSO material required in the {approx}TeV per nucleon region.
A large area silicon array for the next generation of space-based experiments has been designed to determine, via multiple dE/dx measurements, the electric charge of cosmic radiation. The instrument ...can achieve an excellent charge discrimination, thus allowing to assess the elemental composition of charged cosmic rays at relativistic energies. Pairs of silicon sensors segmented into pixels were tested with a beam of fully ionized nuclei from boron to nickel (Z=28) with a kinetic energy of ∼1GeV/amu, at the Fragment Separator (FRS) of the GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt. The response of the sensors to different nuclear species was accurately characterized. The results of the beam test clearly show that a double-layered silicon array can achieve single-element separation with a resolution close to 0.2 electron charge units, in the whole interval of atomic number Z under test.
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► Secondary beta-decaying isotopes as “cosmic clocks” for Galactic cosmic-ray propagation. ► Application of the FDIRC technique to the identification of cosmic-ray isotopes. ► Enhanced ...photostatistics for nuclei of charge
Z compared to particles with
Z
=
1.
Measurements of the relative abundance of cosmic isotopes and of the energy dependence of their fluxes may clarify our present understanding on the confinement time of charged cosmic rays in the Galaxy. Experimental studies of these
propagation clocks have been carried out by balloon and space missions at energies of a few 100
MeV/amu by means of detection techniques based on multiple d
E/d
x sampling, coupled with a measurement of the energy released in a thick absorber. At larger energies, the isotopic separation of light nuclei (as, for instance,
9Be/
10Be) can be achieved by combining a precise measurement of the particle’s rigidity with an high resolution determination of its velocity, via the observation of the Cherenkov effect in a radiator.
In this paper, we propose the introduction – for the first time in a space experiment – of the DIRC technique (Detection of Internal Reflected Cherenkov light) for the identification of cosmic-ray isotopes. This type of detector has been successfully used in electron–positron colliders for particle identification and in particular for
π–K separation. While for particles with unit charge the light yield is a limiting factor, in the case of a nucleus of charge
Z the larger photostatistics (due to the
Z
2 dependence of Cherenkov light emission) is the key to reach an adequate angular resolution to provide a mass discrimination for isotopes of astrophysical interest. We report on the early development phase of a DIRC prototype with a focussing scheme (FDIRC) to collect the Cherenkov light onto a detector plane instrumented with a Silicon PhotoMultiplier (SiPM) array.
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