Given the good performances in terms of geometrical acceptance and energy resolution, calorimeters are the best suited detectors to measure high energy cosmic rays directly in space. However, in ...order to exploit this potential, the design of calorimeters must be carefully optimized to take into account all limitations related to space missions, due mainly to the mass of the experimental apparatus. CaloCube is a three years R&D project, approved and financed by INFN in 2014, aiming to optimize the design of a space-borne calorimeter by the use of a cubic, homogeneous and isotropic geometry. In order to maximize detector performances with respect to the total mass of the apparatus, comparative studies on different scintillating materials, different sizes of crystals and different spacings among them have been performed making use of Monte Carlo simulations. In parallel to this activity, several prototypes instrumented with CsI:Tl cubic crystals have been constructed and tested with particle beams (muons, electrons, protons and ions). Both simulations and prototypes showed that the CaloCube design leads to a good particle energy resolution (< 2% for electromagnetic showers, < 40% for hadronic showers) and a good effective geometric factor (> 3:5 m2 sr for electromagnetic showers, > 2:5 m2 sr for hadronic showers). Thanks to these performances, in 5 years of operation it would be possible to measure the ux of electrons+positrons up to some tens of TeV and the uxes of protons and nuclei up to some units of PeV/nucleon, hence extending these measurements by at least one order of magnitude in energy compared to the experiments currently operating in space.
Extended results on the cosmic-ray electron + positron spectrum from 11 GeV to 4.8 TeV are presented based on observations with the Calorimetric Electron Telescope (CALET) on the International Space ...Station utilizing the data up to November 2017. The analysis uses the full detector acceptance at high energies, approximately doubling the statistics compared to the previous result. CALET is an all-calorimetric instrument with a total thickness of 30 X_{0} at normal incidence and fine imaging capability, designed to achieve large proton rejection and excellent energy resolution well into the TeV energy region. The observed energy spectrum in the region below 1 TeV shows good agreement with Alpha Magnetic Spectrometer (AMS-02) data. In the energy region below ∼300 GeV, CALET's spectral index is found to be consistent with the AMS-02, Fermi Large Area Telescope (Fermi-LAT), and Dark Matter Particle Explorer (DAMPE), while from 300 to 600 GeV the spectrum is significantly softer than the spectra from the latter two experiments. The absolute flux of CALET is consistent with other experiments at around a few tens of GeV. However, it is lower than those of DAMPE and Fermi-LAT with the difference increasing up to several hundred GeV. The observed energy spectrum above ∼1 TeV suggests a flux suppression consistent within the errors with the results of DAMPE, while CALET does not observe any significant evidence for a narrow spectral feature in the energy region around 1.4 TeV. Our measured all-electron flux, including statistical errors and a detailed breakdown of the systematic errors, is tabulated in the Supplemental Material in order to allow more refined spectral analyses based on our data.
This paper presents the first experimental demonstration of a pixelated two-layer Geiger-mode avalanche sensor designed for the direct detection of charged particles. In the proposed device, each ...pixel is formed by two vertically aligned avalanche detectors, exploiting the coincidence between two simultaneous avalanche events to discriminate between the detection of particles and dark counts. A 48 × 16 pixel array has been designed and fabricated in a 150-nm CMOS process and vertically integrated through bump bonding. The pixel, that includes passive quenching, comparator, and digital electronic circuits for coincidence processing and signal storage, has a size of 50 μm × 75 μm and a maximum fill factor of 51.6%. The operation of the particle sensor has been validated with the measurement of dark count rate distribution at different coincidence resolution times. An average dark count rate per pixel as low as 93 mHz, corresponding to 24 Hz/mm 2 , was obtained at room temperature. A first sensor validation using a 90 Sr β source is presented.
The CALorimetric Electron Telescope (CALET) is an astroparticle physics experiment installed on the International Space Station since August 2015. The CALET mission was conceived to address several ...outstanding questions of high-energy astroparticle physics, like indirect detection of dark matter, the origin of cosmic rays (CRs), their mechanisms of acceleration and galactic propagation, the presence of possible nearby astrophysical CR sources. That can be achieved by precise measurements of the fluxes of CR electrons and gamma-rays up to the unexplored region above 1 TeV, and the energy spectra and composition of CR nuclei from a few tens of GeV to hundreds of TeV. In order to perform these observations, the instrument combines a thick total absorption PWO crystal calorimeter for energy measurement, a scintillator hodoscope for charge identi cation and thin imaging tungsten-scintillating fiber calorimeter providing accurate particle tracking and complementary charge measurement.
In this paper, we will present an overview of the main CALET results based on the data collected in the first three years of the mission.
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.
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.
The cosmic-ray energetics and mass (CREAM) investigation is designed to measure cosmic-ray composition to the supernova energy scale of 10
15 eV in a series of ultra long duration balloon (ULDB) ...flights. The first flight is planned to be launched from Antarctica in December 2004. The goal is to observe cosmic-ray spectral features and/or abundance changes that might signify a limit to supernova acceleration. The particle charge (
Z) measurements will be made with a timing-based charge detector and a pixelated silicon charge detector to minimize the effect of backscatter from the calorimeter. The particle energy measurements will be made with a transition radiation detector (TRD) for
Z>3 and a sampling tungsten/scintillator calorimeter for
Z⩾1 particles, allowing inflight cross calibration of the two detectors. The status of the payload construction and flight preparation are reported in this paper.
We present the observation of a charge-sign dependent solar modulation of galactic cosmic rays (GCRs) with the Calorimetric Electron Telescope onboard the International Space Station over 6 yr, ...corresponding to the positive polarity of the solar magnetic field. The observed variation of proton count rate is consistent with the neutron monitor count rate, validating our methods for determining the proton count rate. It is observed by the Calorimetric Electron Telescope that both GCR electron and proton count rates at the same average rigidity vary in anticorrelation with the tilt angle of the heliospheric current sheet, while the amplitude of the variation is significantly larger in the electron count rate than in the proton count rate. We show that this observed charge-sign dependence is reproduced by a numerical “drift model” of the GCR transport in the heliosphere. This is a clear signature of the drift effect on the long-term solar modulation observed with a single detector.
Experimental results obtained with a prototype of a Focused Internal Reflection Cherenkov, equipped with 16 high-granularity arrays of NUV-SiPM and tested at CERN SPS in March 2015, are discussed. ...The detector was exposed to relativistic ions of 13, 19 and 30GeV/amu obtained from fragmentation of a primary Ar beam. The FDIRC included a single Fused Silica radiator bar optically connected to a cylindrical mirror and an imaging focal plane of dimensions ∼4cm×∼3cm, covered with a total of 1024 SiPM photosensors. It was operated in photon counting mode thanks to the excellent performance of the SiPM arrays. The complete simulation of the detector was extended to the case of a planar device with multiple bars covering a sensitive area of the order of 1m2. MC simulation is performed to evaluate its expected mass resolution for the identification of cosmic isotopes of astrophysical interest as 9Be and 10Be at energies of several GeV/amu with the goal to extend the energy reach of the present available data.
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