Browsing by Author "Sakai, Kenichi"
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Item Analysis of CALET Data for Anisotropy in Electron+Positron Cosmic Rays(Proceedings of Science, 2021-07-02) Motz, H.; Asaoka, Y.; Cannady, Nicholas; Hams, Thomas; Krizmanic, John F.; Sakai, Kenichi; CALET Collaboration; et alThe ISS-based Calorimetric Electron Telescope (CALET) is directly measuring the energy spectrum and direction distribution of electron+positron cosmic-rays up to 20 TeV. A main goal of CALET is to identify a signature of a nearby supernova remnant in electron+positron cosmic-rays, such as a spectral feature in the TeV region and/or a detectable anisotropy. The electron+positron events measured by CALET have been analyzed for a possible dipole anisotropy, as well as higher multipole moments. The methods for deriving limits on the anisotropy from the reconstructed events, as well as the procedures to compensate for the non-uniform exposure to the sky and inhomogeneous acceptance of the detector are explained. Preliminary results for the measured anisotropy and upper limits depending on threshold energy are presented, together with sensitivity estimations and a comparison to the expected anisotropy caused by the Vela supernova remnant.Item Analysis Results from the Cosmic Ray Energetics And Mass Instrument for the International Space Station (ISS-CREAM)(Proceedings of Science, 2021-07-12) Nutter, Scott L.; Anderson, Tyler; Chen, Yu; Coutu, Stephane; LaBree, Tyler; Link, Jason T.; Mitchell, John W.; Mognet, S. A. Isaac; Sakai, Kenichi; Smith, Jacob; Yu, MonongWe present the results of an analysis of on-orbit data from the Cosmic Ray Energetics And Mass instrument for the International Space Station (ISS-CREAM). The design objective is to measure the elemental spectra of cosmic rays from Z=1 to Z=26 over the energy range of 10¹² – 10¹⁵ eV. The instrument was installed on the ISS on August 22, 2017 with operations terminated on February 12, 2019, resulting in approximately 1.5 years of operation. We compare detailed GEANT4 simulations to instrument data, demonstrate how we determine the appropriate absolute energy calibration for the instrument, and show some preliminary results.Item The analysis strategy for the measurement of the electron flux with CALET on the International Space Station(Proceedings of Science, 2022-03-18) Berti, E.; Gonzi, S.; Pacini, L.; Akaike, Y.; Cannady, Nicholas; Hams, Thomas; Krizmanic, John F.; Sakai, Kenichi; CALET Collaboration; et alThe CALorimetric Electron Telescope (CALET), operating aboard the International Space Station since October 2015, is an experiment dedicated to high-energy astroparticle physics. The primary scientific goal of the experiment is the measurement of the electron+positron flux up to the multi-TeV region, which can provide unique information on the presence of nearby astrophysical sources and possible signals from dark matter. Other important goals are the ones relative to the flux of nuclear species from proton to iron up to tens of TeV/nucleon and to gamma-ray astronomy up to a few TeV. In order to accomplish these tasks, the CALET instrument was carefully designed exploiting a calorimeter solution composed by three detectors: CHarge Detector (CHD), IMaging Calorimeter (IMC) and Total AbSorption Calorimeter (TASC). This geometry allows for an excellent electromagnetic shower energy resolution (2%), a very high proton rejection factor (105) and a relatively large geometric factor (0.1 m2sr). In this contribution, we present the analysis strategy employed for the measurement of the electron+positron flux, which is divided in two main steps. The first step consists of a group of selections to obtain a sample of well reconstructed candidates, removing particles outside the detector acceptance and particles with a charge Z>1, while keeping a high selection efficiency for electrons. The second step consists of a final rejection to remove the residual proton background: this is the most crucial point of the analysis since in cosmic rays protons are more abundant than electrons by a factor 100-1000. Proton rejection is performed using two different methodologies. We will demonstrate that, at low energies, it is enough to use a simple single cut that makes use of the reconstructed longitudinal and lateral profile, whereas, at high energies, it is necessary to use a more powerful cut that combines all detector information by the use of a multivariate analysis technique. Finally, we will show that this rejection algorithm leads to very stable performances at all energies, strongly reducing the impact of the associated uncertainty, which is the main source of systematic uncertainty in the high energy region.Item CALET on the International Space Station: the first three years of observations(IOP, 2020-05-29) Brogi, P; Adriani, O; Akaike, Yosui; Asano, K; Cannady, Nicholas; Hams, Thomas; Krizmanic, John F.; Link, J.; Sakai, Kenichi; et alThe 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.Item CALET results after three years on the International Space Station(IOP, 2020) Asaoka, Y; Adriani, O; Akaike, Yosui; Asano, K; Cannady, Nicholas; Hams, Thomas; Krizmanic, John F.; Link, J.; Sakai, Kenichi; et alThe 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.Item CALET Ultra Heavy Cosmic Ray Observations on the ISS(Proceedings of Science, 2021-07-02) Rauch, B.F.; Binns, W.; Cannady, Nicholas; Hams, Thomas; Krizmanic, John F.; Sakai, Kenichi; CALET Collaboration; et alThe CALorimetric Electron Telescope (CALET) on the International Space Station (ISS) has made cosmic-ray observations since shortly after its launch in August 2015. The heart of CALET, its main calorimeter (CAL), continues to make the direct measurements of the highest energy cosmic ray total electron spectrum it was designed for. The CAL has also observed gamma rays and cosmic-ray (CR) nuclei, and it has measured energy spectra as well as secondary to primary ratios of the more abundant CR nuclei through 26Fe. In addition, the CAL has measured the ultra-heavy cosmic ray (UHCR) nuclei heavier than 26Fe, and it has demonstrated the dynamic range to measure CR nuclei from 1H to 40Zr. Using the main high energy (HE) CAL trigger mode particle energies can be reconstructed from the energy deposition in the total absorption calorimeter (TASC), and there is also a high duty cycle (∼90%) UHCR trigger providing an expanded geometric acceptance that is ∼6× that for events fully contained by the CAL. In ∼5 years the UHCR trigger will collect a data set comparable to that so far collected by the balloon-borne SuperTIGER instrument. Preliminary CALET results presented at the last ICRC were in reasonable agreement with SuperTIGER relative abundances of even charge UHCR nuclei in a similar energy range. Both of these measurements are complemented by the ∼1/3 smaller lower-energy space-based ACE-CRIS measurements. We present the current status and future plans for the CALET UHCR analysis.Item CALET Ultra-Heavy Cosmic-Ray Observations Incorporating Trajectory Dependent Geomagnetic Rigidities(2020-04-20) Rauch, Brian; Zober, Wolfgang; Cannady, Nicholas; Hams, Thomas; Krizmanic, John F.; Sakai, Kenichi; CALET Collaboration; et alCALET Ultra-Heavy Cosmic-Ray Observations Incorporating Trajectory Dependent Geomagnetic Rigidities BRIAN RAUCH, WOLFGANG ZOBER, Washington University, St. Louis, FOR THE CALET COLLABORATION — The CALorimetric Electron Telescope (CALET), launched to the International Space Station (ISS) in August 2015, continues to measure cosmic-ray (CR) electrons, nuclei and gamma-rays. The main calorimeter (CAL) has a 30 radiation length deep calorimeter for high energy electrons that also measures the energy spectra and secondary to primary ratios of the more abundant CR nuclei through 26Fe. The CAL charge detector has the dynamic range to measure CR nuclei from 1H to 40Zr, but to maximize the acceptance of the rare ultra-heavy (UH) CR above 30Zn a special high duty cycle (∼90%) UH trigger is used that does not require passage through the main calorimeter. Forgoing the calorimeter energy measurement provides a ∼6× increase in geometry factor that reduced by ISS obstructions allows CALET to collect in 5 years a UHCR data set similar to that from the first flight of the balloon-borne SuperTIGER instrument. Previous CALET UHCR analyses using time and position corrections based on 26Fe and a geomagnetic vertical cutoff rigidity selection have shown abundances of even nuclei in agreement with SuperTIGER/ACE-CRIS. To further improve resolution and maximize statistics a trajectory dependent geomagnetic rigidity selection is employed here.Item CALET upper limits on GeV-energy gamma-ray burst emission(Proceedings of Science, 2019-07-24) Cannady, Nicholas; Hams, Thomas; Krizmanic, John F.; Sakai, Kenichi; CALET Collaboration; et alThe CALorimetric Electron Telescope (CALET) was deployed on the International Space Station in October 2015 and has accumulated over three years of continuous data to date. The calorimeter (CAL) is sensitive to gamma rays with energies above 1 GeV, and the response has been characterized up to hundreds of GeV. In this work we investigate counterpart GeV-energy emission to gamma-ray bursts observed by the CALET Gamma-ray Burst Monitor and the Swift and FermiGBM missions. The methodologies for the event search and the setting of upper limits in the case of non-detection are presented, along with results from the first three years of CALET operations, covering over 100 GRBs.Item The CALorimetic Electron Telescope (CALET) on the International Space Station(Elsevier, 2019-11-21) Torii, Shoji; Marrocchesi, Pier Simone; Cannady, Nicholas; Hams, Thomas; Krizmanic, John F.; Sakai, Kenichi; CALET Collaboration; et alThe CALorimetric Electron Telescope (CALET) space experiment, developed by Japan in collaboration with Italy and the United States, is a high-energy astroparticle physics mission installed on the International Space Station (ISS). The primary goals of the CALET mission include investigating on the possible presence of nearby sources of high-energy electrons, studying the details of galactic particle propagation and searching for dark matter signatures. During a two-year mission, extendable to five years, CALET can measure the flux of cosmic-ray electrons (including positrons) to 20 TeV, gamma-rays to 10 TeV and nuclei with Z = 1 to 40 up to 1,000 TeV. The instrument consists of two layers of segmented plastic scintillators for cosmic-ray charge identification (CHD), a 3 radiation length thick tungsten-scintillating fiber imaging calorimeter (IMC) and a 27 radiation length thick lead-tungstate calorimeter (TASC). CALET has sufficient depth, imaging capabilities and excellent energy resolution to allow for a clear separation between hadrons and electrons and between charged particles and gamma rays. The instrument was launched on August 19, 2015 to the ISS with the H-II Transfer Vehicle 5 (HTV-5) and installed on the Japanese Experiment Module-Exposed Facility (JEM-EF) on August 25. Since the start of operations in mid-October, 2015, a continuous observation has been going on mainly by triggering high energy (>10 GeV) showers without any major interruption. The number of triggered events above 10 GeV is nearly 20 million per month. By using the data obtained during the first two years, we give a summary of CALET observations: (1) Electron + Positron energy spectrum, (2) Proton and Nuclei spectrum, (3) Gamma-ray observation, with results of the performance study on orbit. We also present the results of observations of the electromagnetic counterparts to LIGO-VIRGO gravitational wave events and high-energy counterparts to GRB events measured with the CALET Gamma-ray Burst Monitor (CGBM).Item The CALorimetric Electron Telescope (CALET) on the International Space Station(Proceedings of Science, 2021-07-02) Asaoka, Y.; Cannady, Nicholas; Hams, Thomas; Krizmanic, John F.; Sakai, Kenichi; CALET Collaboration; et alThe CALorimetric Electron Telescope (CALET), developed and operated by Japan in collaboration with Italy and the United States, is a high-energy astroparticle physics experiment installed on the International Space Station (ISS). Its mission goals include investigating nearby possible sources of high-energy electrons, elucidating the details of the acceleration and propagation of galactic particles, and detecting potential dark matter signatures. CALET measures cosmic-ray electron+positron flux up to 20 TeV, gamma rays up to 10 TeV, and nuclei with Z=1 to 40 up to 1,000 TeV for the more abundant elements during long-term observations. CALET has performed continuous observations without major interruptions since mid-October 2015, recording approximately 20 million triggered events per month with energies greater than 10 GeV. Here, we present the highlights of CALET observations made over the first three years of operation, namely the electron+positron energy spectrum, the spectra of protons and other nuclei, and gamma-ray observations, including the characterization of on-orbit performance. Some results of the electromagnetic counterpart search for LIGO/Virgo gravitational wave events are also included.Item The CALorimetric Electron Telescope (CALET) Status and Initial Results(2019-04-13) Guzik, T Gregory; Cannady, Nicholas; Hams, Thomas; Krizmanic, John F.; Sakai, Kenichi; CALET Collaboration; et alThe CALET space experiment, that was developed by collaborators in Japan, Italy and the United States, has been mounted as an attached payload on the International Space Station (ISS) Japanese Experiment Module – Exposed Facility (JEM-EF) since August 2015. Over the >1,000 days of data taking the instrument has accumulated more than ~630 million triggered events > 10 GeV with a live time fraction of 84%. These data have been used to study electrons to ~5 TeV, gamma rays above 10 GeV and nuclei with Z=1 to 40 up to 1,000 TeV. Multiple peer-reviewed journal publications detailing the CALET results are now available. The instrument consists of a particle charge identification module, a thin imaging calorimeter (3 r.l. in total) with tungsten plates interleaving scintillating fiber planes, and a thick calorimeter (27 r.l.) composed of lead tungstate logs. CALET has the depth, imaging capabilities and energy resolution for excellent separation between hadrons, electrons and gamma rays. This presentation summarizes the instrument design, on-orbit performance, and provides highlights of the most important CALET results over the last three years.Item The CALorimetric Electron Telescope (CALET): Continuing Operations on the ISS(2020-04-18) Rauch, B.; Cannady, Nicholas; Hams, Thomas; Krizmanic, John F.; Sakai, Kenichi; CALET Collaboration; et alThe CALorimetric Electron Telescope (CALET): Continuing Operations on the ISS1 BRIAN RAUCH, Washington University, St. Louis, FOR THE CALET COLLABORATION — The CALorimetric Electron Telescope (CALET) is a high-energy astroparticle physics experiment on the International Space Station (ISS) developed and operated by Japan in collaboration with researchers in Italy and the US. In extended observations the main calorimeter (CAL) can measure the cosmic-ray electron+positron spectrum up to 20 TeV, gamma rays up to 10 TeV, and nuclei from 1H to 40Zn up to 1,000 TeV. The CAL is comprised of a two-layer scintillator paddle charge detector, a scintillating fiber imaging calorimeter with 3 radiation lengths (RL) of tungsten plates, and a 27 RL deep lead tungstate total absorption calorimeter. There is also the CALET Gamma-ray Burst Monitor (CGBM) subsystem with two hard X-ray monitors (HXM) sensitive to 7-1000 keV photons and a soft gamma-ray monitor (SGM) sensitive to 100 keV20 MeV photons utilizing two LaBr3 (Ce) and one BGO scintillators, respectively. Major CALET results to date include measurements of the electron+positron energy spectrum to ∼5 TeV, the spectra of protons and other nuclei, and gamma-ray observations including LIGO/Virgo counterpart searches. CALET began science operations in mid-October 2015 and is now approved to continue through March 2021 with the possibility that operations may be extended further.Item Cosmic-Ray Electron Flux from 1 GeV to 10 GeV with Low-Energy Trigger in the CALET Experiment(2018-07-19) Miyake, Shoko; Migita, Yotaro; Ando, Yuki; Asaoka, Yoichi; Akaike, Yosui; Torii, Shoji; Terasawa, T.; Kataoka, Ryuho; Sakai, Kenichi; Cannady, Nicholas; CALET Collaboration; et al.Item Determination of Expected TIGERISS Observations(Proceedings of Science, 2022-03-18) Rauch, B.F.; Walsh, N.E.; Zober, W.V.; Cannady, Nicholas; Krizmanic, John F.; Sakai, Kenichi; TIGERISS Collaboration; et alWe present the method used to estimate the cosmic-ray observations expected for that the Trans-Iron Galactic Element Recorder for the International Space Station (TIGERISS), which is designed to measure the abundances of the rare Ultra-Heavy Galactic Cosmic Rays (UHCR) 30Zn and heavier. TIGERISS uses planes of crossed silicon strip detectors at the top and bottom for charge and trajectory determination and acrylic and aerogel Cherenkov detectors for velocity and charge determination. Instruments are modeled in configurations for the Japanese Experiment Module (JEM) "Kibo" Exposed Facility (∼1.66 m2 sr), as an European Space Agency Columbus Laboratory external payload (∼1.16 m2 sr), and as an ExPRESS Logistics Carrier (ELC) experiment (∼1.10 m2 sr). Differential geometry factors determined for detector orientations within the geomagnetic field over the ISS 51.6∘ inclination orbit are used to determine geomagnetic screening. Energy spectra are integrated using the higher of the energies needed to trigger the instrument or penetrate the geomagnetic field for time-weighted bins of geomagnetic latitude, instrument orientation, and incidence angle. Finally, abundances are reduced by the fraction of events calculated to fragment in the instrument.Item Determining Angle Dependent Effective Rigidity Cutoffs for ISS-CALET Ultra-Heavy Cosmic-Ray Analysis(2020-04-18) Zober, Wolfgang; Cannady, Nicholas; Hams, Thomas; Krizmanic, John F.; Sakai, Kenichi; CALET Collaboration; et alDetermining Angle Dependent Effective Rigidity Cutoffs for ISSCALET Ultra-Heavy Cosmic-Ray Analysis WOLFGANG ZOBER, Washington University, St. Louis, AND THE CALET COLLABORATION — The CALorimetric Electron Telescope (CALET) has been collecting data on the International Space Station (ISS) since shortly after its launch in August 2015. Its main calorimeter (CAL), is designed to measure the fluxes of the highest energy cosmic-ray electrons, but has also made excellent measurements of cosmic-ray (CR) nuclei and gamma rays. Ultra-heavy (UH) CR events are screened by the geomagnetic field, which the preliminary analysis has used for a vertical cutoff rigidity to determine a minimum energy threshold for valid events. Current work is now being done to improve this energy threshold to boost statistics and resolution in UHCR measurements by calculating an angle dependent effective cutoff rigidity. This has been explored in two ways: an angle dependent Stoermer approximation and a ray-tracing program that calculates the effective cutoff by determining allowed trajectory energies with a Cash-Karp Runge-Kutta that was inspired by the work of D.F. Smart and M.A. Shea. These methods have found use in UHCR analysis and could be used in a positron-electron spectra calculation. Here we present the current state of the analysis and show the improvements in the data thus far from properly accounting for the trajectory of the detected nuclei.Item Direct Measurement of the Cosmic-Ray Carbon and Oxygen Spectra from 10 GeV/n to 2.2 TeV/n with the Calorimetric Electron Telescope on the International Space Station(APS, 2020-12-18) Adriani, O.; Akaike, Y.; Asano, K.; Asaoka, Y.; Cannady, Nicholas; Hams, Thomas; Krizmanic, John F.; Link, J.; Sakai, Kenichi; CALET Collaboration; et alIn 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.Item Direct Measurement of the Cosmic-Ray Proton Spectrum from 50 GeV to 10 TeV with the Calorimetric Electron Telescope on the International Space Station(American Physical Society, 2019-05-10) Adriani, O.; Akaike, Yosui; Asano, K.; Asaoka, Y.; Cannady, Nicholas; Hams, Thomas; Krizmanic, John F.; Sakai, Kenichi; CALET Collaboration; et alIn this paper, we present the analysis and results of a direct measurement of the cosmic-ray proton spectrum with the CALET instrument onboard the International Space Station, including the detailed assessment of systematic uncertainties. The observation period used in this analysis is from October 13, 2015 to August 31, 2018 (1054 days). We have achieved the very wide energy range necessary to carry out measurements of the spectrum from 50 GeV to 10 TeV covering, for the first time in space, with a single instrument the whole energy interval previously investigated in most cases in separate subranges by magnetic spectrometers (BESS-TeV, PAMELA, and AMS-02) and calorimetric instruments (ATIC, CREAM, and NUCLEON). The observed spectrum is consistent with AMS-02 but extends to nearly an order of magnitude higher energy, showing a very smooth transition of the power-law spectral index from −2.81 ± 0.03 (50–500 GeV) neglecting solar modulation effects (or −2.87 ± 0.06 including solar modulation effects in the lower energy region) to −2.56 ± 0.04 (1–10 TeV), thereby confirming the existence of spectral hardening and providing evidence of a deviation from a single power law by more than 3σ.Item Energy spectra of carbon and oxygen cosmic rays with CALET on the International Space Station(Proceedings of Science, 2022-03-18) Maestro, Paolo; Cannady, Nicholas; Hams, Thomas; Krizmanic, John F.; Link, J.; Sakai, Kenichi; CALET Collaboration; et alWe present the measurements of the energy spectra of carbon and oxygen nuclei in cosmic rays based on 4 years of observation with the Calorimetric Electron Telescope (CALET) on the International Space Station. The energy spectra are measured 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 and equipped with charge detectors capable of single element resolution. Data analysis, including the detailed assessment of systematic uncertainties, and results are reported. The observed carbon and oxygen fluxes show a spectral hardening around 200 GeV/n established with a significance > 3σ. They have the same energy dependence and a constant C/O flux ratio above 25 GeV/n. These measurements will contribute to a better understanding of the origin of the spectral hardening.Item Extended Measurement of Cosmic-Ray Electron and Positron Spectrum from CALET on the ISS(Proceedings of Science, 2021-07-02) Torii, S.; Asaoka, Y.; Cannady, Nicholas; Hams, Thomas; Krizmanic, John F.; Sakai, Kenichi; CALET Collaboration; et alThe CALET (CALorimetric Electron Telescope), launched to the International Space Station (ISS) on August 19, 2015 and accumulating scientific data since October 13, 2015, is an all-calorimetric instrument with total vertical thickness of 30 radiation lengths and fine imaging capability, optimized for a measurement of the electron and positron (all-electron) spectrum well into the TeV energy region. CALET will allow for the detailed search for various spectral structures of high-energy all-electron cosmic rays, perhaps providing the first experimental evidence of the presence of a nearby astrophysical cosmic-ray source. All-electron spectrum analysis starts with detailed detector calibrations covering from detector alignment to energy determination, followed by electron event selection and flux normalization. Special care was taken to identify electrons in the presence of a large hadron background. Possible source of systematic errors are carefully surveyed, and associated uncertainties are estimated for each contribution. As a result, all-electron spectrum is obtained including the TeV energy range. In this contribution, we will present the all-electron spectrum measured by CALET and compare it with those obtained by other experiments.Item Extended measurement of the proton spectrum with CALET on the International Space Station(Proceedings of Science, 2022-03-18) Kobayashi, K.; Marrocchesi, P. S.; Cannady, Nicholas; Hams, Thomas; Krizmanic, John F.; Sakai, Kenichi; CALET Collaboration; et alCALET is aiming to measure the main components of high energy cosmic rays up to ~1 PeV in order to understand the cosmic ray acceleration and propagation. Using CALET data from Oct. 2015 to Sep. 2020, we have extended the measurement of the cosmic ray proton spectrum from PRL2019. Statistics has been increased by more than two years. We confirm the spectral hardening around ~500GeV that was reported in PRL2019. We also expand the energy region to E<60TeV and observed a spectral softening in E>10TeV as well. By double broken power law fitting, it is obtained that the hardening at 550±130GeV and the softening at 11±4TeV.
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