Fumiyoshi Kajino

The JEM-EUSO Mission

The JEM‐EUSO mission explores the origin of the extreme energy cosmic rays (EECRs) above 100 EeV and explores the limits of the fundamental physics, through the observations of their arrival directions and energies. It is designed to achieve an exposure larger than 1 million km2 sr year at the highest energies to open a new particle astronomy channel. This super‐wide‐field of view (60 degrees) telescope with a diameter of about 2.5 m looks down from space onto the night sky to detect near UV photons (330–400 nm, both fluorescent and Cherenkov photons) emitted from the giant air showers produced by EECRs. The arrival direction map with more than five hundred events after just the three years will tell us the origin of the EECRs, allow us to identify the nearest EECR sources with known astronomical objects, which can afterwards be examined in other astronomical channels. This is likely to lead to an understanding of the acceleration mechanisms perhaps producing discoveries in astrophysics and fundamental ph...

Performance of a compensating lead/plastic scintillator tile/fiber calorimeter

Abstract We have measured performance of a lead/plastic scintillator sampling calorimeter in two separate beam tests at low (1– 4 GeV ) and high (10– 200 GeV ) energies. The calorimeter is composed of 8-mm-thick lead plates and 2-mm-thick plastic scintillator plates for hardware compensation, where responses to electromagnetic and hadronic showers of the same energy are identical. We find the linearity to be better than 1% in the energy range between 2 and 150 GeV for both pions and electrons. The energy resolutions are obtained to be (46.7±0.6)%/ E ⊕(0.9±0.9)% for pions, where the energy E is given in GeV. The response ratio of electromagnetic showers to hadronic showers is measured to be 1.04±0.01 at low energies, and 0.99±0.01 at high energies.

The focal surface of the JEM-EUSO instrument

The Extreme Universe Space Observatory on JEM/EF (JEM-EUSO) is a space mission to study extremely high-energy cosmic rays. The JEM-EUSO instrument is a wide-angle refractive telescope in the near-ultraviolet wavelength region which will be mounted to the International Space Station. Its goal is to measure time-resolved fluorescence images of extensive air showers in the atmosphere. In this paper we describe in detail the main features and technological aspects of the focal surface of the instrument. The JEM-EUSO focal surface is a spherically curved surface, with an area of about 4.5 m2. The focal surface detector is made of more than 5000 multi-anode photomultipliers (MAPMTs). Current baseline is Hamamatsu R11265-03-M64. The approach to the focal surface detector is highly modular. Photo-Detector-Modules (PDM) are the basic units that drive the mechanical structure and data acquisition. Each PDM consists of 9 Elementary Cells (ECs). The EC, which is the basic unit of the MAPMT support structure and of the front-end electronics, contains 4 units of MAPMTs. In total, about 1 200 ECs or about 150 PDMs are arranged on the whole of the focal surface of JEM-EUSO.

Performance of preshower and shower-maximum detectors with a lead/plastic-scintillator calorimeter

Abstract The electron/hadron separation in the calorimetry can be improved if we measure the electromagnetic shower development at an early stage. The incident positions of electrons and photons can be precisely measured with a position sensitive detector placed near the electromagnetic shower maximum. We constructed a set of prototype preshower and shower-maximum detectors to be attached in front of a main calorimeter. Performance of the detectors was studied in combination with a lead/plastic-scintillator calorimeter module using high energy beams up to 100 GeV at a test beam facility at Fermi National Accelerator Laboratory.

SPACIROC: A front-end readout ASIC for the JEM-EUSO observatory

The SPACIROC ASIC is designed for the JEMEUSO observatory onboard of the International Space Station (ISS). The main goal of JEM-EUSO is to observe Extensive Air Shower (EAS) produced in the atmosphere by the passage of the high energetic extraterrestrial particles above a few 10^19 eV. A low-power, rad-hard ASIC is proposed for reading out the 64-channel Multi-Anode Photomultipliers which will equip the detection surface of JEM-EUSO. Two main features of this ASIC are the photon counting mode for each input and the charge-totime (Q-to-T) conversion for the multiplexed channels. In the photon counting mode, the 100% triggering efficiency is achieved for 50 fC input charges. For the Q-to-T converter, the ASIC requires a minimum input of 2 pC. In order to comply with the strict power budget available from the ISS, the ASIC is needed to dissipate less than 1 mW/channel. The design of SPACIROC and the test results are presented in this paper. SPACIROC is a result of the collaboration between OMEGA/LAL-Orsay, France, RIKEN, ISAS/JAXA and Konan University, Japan on behalf of the JEM-EUSO consortium.

Novel direct vision prism and Wollaston prism assembly for diffraction limit applications

We propose two types of novel prisms; 1) a direct vision prism with approximately linear angular dispersion as a function of wavelength (Liner dispersion prism: LDP) suitable for a wide range spectrometer, and 2) a novel Wollaston prism assembly (WPA) suitable for a polarizing imager and spectro-polarimeter with a wide wavelength coverage. LDP composes several kinds of glasses or plastics or crystals. Angular dispersion of LDP is enlarged by employment of with some kind of plastic. LDPs, which are employed polycarbonate and Cytop (Amorphous fluorocarbon resin), provide approximately linear angular dispersion in ultraviolet and visible wavelength, respectively. WPA is composed of two or three kinds of Wollaston prism with different birefringent crystals. WPA provides an achromatic angular separation or an angular separation with linear dispersion. These prisms will enable us to achieve a diffraction-limited capability on next generation telescopes of both ground-based and space-borne.

Performance studies of a lead-scintillation fiber calorimeter prototype for the linear collider detector

Abstract We constructed calorimeter modules composed of lead plates and scintillating fibers as an R&D program for the experiment at a future electron-positron linear collider. We tested the performance of the modules using electron and pion beams at the KEK proton synchrotron. The results of the beam tests are presented in this paper.

The Science Case of the JEM‐EUSO Mission‐Unveiling the Universe at ultra‐high energies

The Extreme Universe Space Observatory onboard the Japanese Experiment Module is an international mission designed to identify the astrophysical origin and physical nature of ultra high‐energy (UHE) cosmic particles with energies E>7×1019 eV. It uses a near‐UV 2.5 m diameter telescope with a field of view of 60 degrees to detect the fluorescence and Cherenkov light emitted along the linear track generated by UHE particle traversing the earth’s atmosphere. The JEM‐EUSO mission is designed to observe at least 103 particles. The energy and arrival direction of each particle will be accurately measured while all‐sky is covered and monitored. The primary science goal of the mission is particle astronomy. The high statistics of JEM‐EUSO will be essential to identify the sources of the highest energy particles, and to measure their spectrum. This will allow a deeper understanding of the production, acceleration, and in situ propagation mechanisms of UHE cosmic rays. Through the study of the sky distribution of t...

SILICON PAD DETECTOR FOR A CALORIMETER AT JLC

Abstract A silicon-pad detector with 216 read-out channels for a calorimeter was built and tested using electron and pion beams in the energy range of 1 to 4 GeV. Separation of electrons from pions is calculated from the data.

SPACIROC2: A front-end readout ASIC for the JEM-EUSO observatory

The SPACIROC ASIC is designed for the JEMEUSO observatory onboard of the International Space Station (ISS). The main goal of JEM-EUSO is to observe Extensive Air Shower (EAS) produced in the atmosphere by the passage of the high energetic extraterrestrial particles above a few 10^19 eV. A low-power, rad-hard ASIC is proposed for reading out the 64-channel Multi-Anode Photomultipliers which will equip the detection surface of JEM-EUSO. Two main features of this ASIC are the photon counting mode for each input and the charge-totime (Q-to-T) conversion for the multiplexed channels. In the photon counting mode, the 100% triggering efficiency is achieved for 50 fC input charges. For the Q-to-T converter, the ASIC requires a minimum input of 2 pC. In order to comply with the strict power budget available from the ISS, the ASIC is needed to dissipate less than 1 mW/channel. The design of SPACIROC and the test results are presented in this paper. SPACIROC is a result of the collaboration between OMEGA/LAL-Orsay, France, RIKEN, ISAS/JAXA and Konan University, Japan on behalf of the JEM-EUSO consortium.