High Technologies
are Supporting JEM-EUSO
Fresnel Lens #2

Comparison of JEM-EUSO with the largest ground observatories
AGASA

HiRes

Auger

Telescope Array

JEM-EUSO

Organization

University of Tokyo

University of Utah

InternationalConsortium

University of Tokyo
and University of Utah

International
Consortium

Location

Yamanashi, JapanUtah, USA

Argentina

Utah, USAInternational
Space Station

Type of Detectors

Ground Array

Fluorescence
Ground Telescope

Period of operations

1990–2004

1997–2006

2005–

2007–

launch expected
in 2013150500~7,000760

125,00050 (expected),
3 (observed)

10 (expected)

350 – 1,700(expected)

Electronics

Precision Fresnel lensSupport of Focal Surface Structure
Iris

Effective aperture(km2·sr)
Focal Surface Detectors

Yield of EHE events(No./year)

Fresnel Lens
Fresnel lens #1

Realizing a wide field-of-viewand light-weight

Structure

2.26m

Focal Surface
Detectors

6,000 photomultiplierst

The focal surface is curved with adiameter of 2.26m. About 6,000
1-inch square multianode photomultiplier tubes (PMTs) detect the lightfrom the different locations in theearth’s atmosphere. Earlier PMTs had
a limited photo-sensitive area of only
45%. JEM-EUSO and Hamamatsu
Photonics jointly developed PMTs tohave a higher effective area of 85%.

The JEM-EUSO telescope uses Fresnel lenses. A Fresnel lens isa semi-flat lens having circular grooves that eliminate thelarge mass of a standard convective or concave lens. A thinand light Fresnel lens is necessary for use in space,
performing the optical functions in the same way as a thickand heavy lens. JEM-EUSO uses two curved double-sided
Fresnel lenses of UV-transmitting plastic and one
micro-grating Fresnel lens. This design allows the best
efficiency for the widest field-of-view. The size of thetriple-lens is 2.5-m diameter, composed of the central 1.5-m
part and the circular outer annular lenses.

Focal Surface

It consists of 164 modules,
and the total number of
PMTs is 5,904.

2.5mt

Light-sensing module

Launcht

Covering a focal surface of
2.26m diameter with 5,904
PMTs, each PMT having 6 × 6=36 photo-sensitive units.

Central lens and annular lenses configuration enable a lens size
larger than can be manufactured on a single machine.

JAXA’s Space Station TransferVehicle (HTV) carries JEM-EUSOt

Photomultipliers

The PMT surface has 85%
active area, having 6 × 6pixels with a total area of26.2 mm square.

Ground Array +Ground Array +Fluorescence Ground Telescope Fluorescence Ground Telescope

1,observed less than 1,
experiments terminated experiments terminatedFluorescenceSpace Telescope

Mission Operation of JEM-EUSO
Altitude

about 400km

Number of pixels of the focal surface about 0.2 million

Observation latitude and longitude

N51°– S51° × all longitudes

Resolution of the groundabout 0.8km

Filed of view

60°

Duty cycle

12–25%

Aperture (ground area size)

0.2 million km²

Mission duration

3 (+2) years

Diameter of telescope

2.5m

Total mass

~1.9 ton

Optical system

Two double-sided Fresnel lens anda high-precision Fresnel lensPower usage< 1kW

International Partners
Japan

RIKEN Konan Univ. Fukui Tech. Univ. Aoyama Gakuin Univ. Saitama Univ. NIRS Univ. Tokyo
Tohoku Univ. ICRR, Univ. Tokyo KEK Chiba Univ. NAOJ ISAS/JAXA Kanazawa Univ. Nagoya Univ.
STE Lab., Nagoya Univ. Yukawa Inst., Kyoto Univ. Kyoto Univ. Kobe Univ. Kinki Univ. Hiroshima Univ.
Hokkaido Univ Tokyo Inst. Tech.

USA

NASA/MSFC

UAHFrance

APC-Paris 7

LAL, IN2P3-CNRS

Germany

MPI Munich

Univ. Tuebingen

Italy

Univ. Florence Univ. Naples Univ. Palermo Univ. Rome “Tor Vergata”
INOA/CNR IASF-PA/INAF IFSI-TO/INAF INFN

MexicoICN-UNAM

Republicof Korea

Ehwa W. Univ. Yonsei Univ.

RussiaSINP MSU

Switzerland

Neuchatel, CSEM

Spain

Univ. Alcalá

PolandIPJ

Slovakia

Inst. Experimental Physics, KOSICE

BUAP

LBL, UCBUCLA Vanderbilt Univ. Univ. Arizona.

MPI BonnUniv. Erlangen

LMU&MPQ
Univ. Turin

UMSNH

Dubna JINR

New Astronomy using Earth’s Atmosphere as a Gigantic Observatory

IACETH

Podlasie Univ. Kielce Univ. Jagiellonian Univ.

JEM-EUSO Collaboration

HTV will be launched by a H-IIB rocket (JAXA)
and autonomously carry JEM-EUSO to ISS.
Robotic arms of ISS will deploy JEM-EUSO at
JEM module of “Kibo.”

Computational Astrophysics Laboratory, RIKENt

Space Station Transfer Vehicle (HTV) approaching ISS ©JAXA

2-1 Hirosawa, Wako, Saitama 351-0198 Japan
Tel : +81-48-467-9417
Fax : +81-48-467-4078
E-mail : jem-euso-staff@riken.jp URL : http://jemeuso.riken.jp/July 2009

GenesisExtreme Universe Space Observatory
onboard Japanese Experiment Module

JEM-EUSO

AGASA

Highest energy above 1020eV
observed in the world

International Space Station (ISS)Supernova explosion ©NASA et al.

Gamma ray burst ©BeppoSAX TeamPulsar ©NASA et al.

tThousands of charged particles bombard the Earth at every 1 m² eachsecond. They are called cosmic rays. Their flux decreases with increasing
particle energy. Arriving cosmic rays with energies above 4 × 10¹⁹ eV are
expected to be extremely suppressed by losses due to collisions withmicrowaves throughout the universe.
After the discovery of an event of 10²⁰ eV* in 1962 by Linsley, a dozen
new events were observed in 1990s by the Akeno-Giant-Air-Shower-Array(AGASA) from the University of Tokyo and Fly’s Eye/Hi-Res experimentfrom the University of Utah. The origin of these highest energy particles is
unknown and fascinating, and attracts considerable scientific interests.

Capture ultraviolet raysfrom an air shower

Radio galaxy ©NRAOtSource candidates of extremely high energy particles include unknown stellar bodies

Is relativity limited?
Are there unknown objects and mechanisms?

The expected suppression of the highest energy particles wastheoretically predicted by Greisen, Zatsepin and Kuz’min (GZKcutoff ) on the basis of the fact that the universe is filled withthe cosmic microwave background (CMB) - the mostprominent remnant of the Big-Bang. Highest energy cosmic
rays collide with the CMB and lose energy within a distance of
150 million light-years (50 Mega parsec) of their passages, until
their energies are reduced to 4 × 10¹⁹ eV (so long as Einstein’s
Special Relativity is valid at any energy and everywhere in theentire universe).

The fact that particles with energies significantly above theGZK-cutoff energies have been observed challenges ourunderstanding of physics and astrophysics. There may besignificant sources of the highest energy particles near ourgalaxy within 50Mpc. Sources could include the well-known
brightest radio-galaxies (Centaur-A and Virgo M-87), or could
be unknown objects. If none of the events point toward anyknown objects, then a bizarre doubt in special relativity orother fundamental physics principles may be invoked. Theobservations to date may or may not be right, and the puzzle
at the energy frontier of universe is awaiting more decisiveexplorations.

ExtrehighergyObserving earth from International Space Station

JEM-EUSO was planned to decisively resolve the GZK-suppression and toidentify the astronomical origin of these particles. JEM-EUSO can detect
1,000 particles above 7 × 10¹⁹ eV in a three year mission. The energy andtheir direction will be accurately measured to clarify the origin of thehighest-energy particles.
The Japan Experiment Module (JEM) on the International Space Station(ISS) will host JEM-EUSO. This astronomical telescope is not directed

toward the universe, but rather looks down toward the earth's surface.
Whereas an ordinary astronomical observatory looks up at the universe
from earth, JEM-EUSO observes the universe by looking toward the earth
because the earth’s atmosphere is the largest detector yet employed in
our quest to understand the origins of these elusive particles comingfrom the universe. JEM-EUSO is a new type of astronomical observatory,
namely, an “earth-observing” astronomical telescope.

Low energy charged particles are bent by magnetic fields in intergalactic and galactic space.
The directional information of their origin is lost. However, the highest energy particles arebarely bent, and so retain their information of the direction to the origin. In this way, highest
energy particles qualify as cosmic messengers for astronomy, alongside visible light, X-rays,
and Infrared light.
Various origins that could generate high energy particles have been postulated:candidates include supernovae, gamma-ray bursts, active galactic nuclei, pulsars, and recent
collisions of radio galaxies and their super-massive central black holes. Most of thesesuggestions are, however, incapable of accelerating particles beyond 10²⁰ eV by any known
mechanism. It has been a consensus that there must be some unknown acceleration
mechanism, or even a non-acceleration mechanism powering extreme energies.
Earth’s atmosphere

en

18

10 eV

19

10 eV

20

10 eV

cos

Fluorescent UV raysmicraystLow-energy charged particles are bentand wound by magnetic fields, but thoseabove 10²⁰ eV travel along almost straight
trajectories with little influence frommagnetic fields, thereby keeping theoriginal directional information.

Air ShowerAir Shower

Expected direction of origins for thehighest-energy particles (1,000 eventswith JEM-EUSO). Multiple events cluster ata point where the strong origin is located.

Exploration of neutrinos at the highest energy

Monitoring the atmospheric illumination from whole earth

Neutrinos barely interact with matter and are not subject to theGZK-cutoff. No events have been detected so far because of thevery low yield with the limited detector mass. Extremely
high-energy neutrinos may be observable with JEM-EUSO,
because the whole atmosphere of earth gives a sufficiently
large target mass for detection of a few events per year.

JEM-EUSO can detect transient atmosphericilluminating events in the night-sky: Examples arelightnings, meteors, and air-glows. Lightning occurs
between clouds and earth, and between clouds.
Some of the most exciting illumination events arelarge-scale upper-atmospheric discharge, called
blue-jets, sprites, and elves. These events streamout of clouds to outer space. How often and where
they occur on the earth’s globe will be monitored,
to help explore the cause of these tantalizing
phenomena. Meteors are small solids from spacediving into the earth’s atmosphere. Observations of
their size and fluorescent spectra are expected tohelp us learn about their mother asteroids, andother solar-system sources.

Energy Frontier – exceeding LHC Physics
The largest man-made accelerator, the “Large Hadron Collider”(LHC), began operation in 2008. It generates high-energy
particles to explore fundamental physics. Highest-energy
cosmic rays discovered so far have laboratory energies morethan three orders of magnitude higher. The energy frontier offundamental physics can be extended by the highest-energy
cosmic particles to be observed by JEM-EUSO.

ton International Space Station explores
the origin of the highest energy particles in Universe.

snotriu
Net

Earth’s atmosphere photographed from Space Shuttle ©NASA

Outcome from JEM-EUSO space telescope

Astronomy by Charged Particles in Universemely

A very large area for observation is necessary to observe the rarehighest-energy events. The University of Tokyo’s Institute for Cosmic
Ray Research has just constructed the “Telescope Array” experiment,
400km
with an area of 760 km², in Utah, USA, as the successor to AGASA. The JEM-EUSO tilted mode
largest array currently in existence, with an area of 3,500 km², started
in 2005 in Argentina, is the Pierre Auger Observatory (PAO). (PierreJEM-EUSO
Auger is the name of a French scientist who first discovered airshowers 70 years ago). Ground-based observatories are limited toobserve the northern, or the southern sky, but not both.
AGASA 10km
The ground detectors of these large observatories have nearlyAuger 50km
reached the maximum extent possible on earth. A remote-sensing
space observatory, JEM-EUSO, makes a giant leap in the observational area size, to 100,000 – 500,000 km² (more than athousand times AGASA) by having a vantage point 400 km in the sky and having a wide field-of-view of 60°. The ISS flies
over both northern and southern hemispheres. A uniform all-sky observation by a single device allows us to search forcorrelations with all known objects.

Challenge

Cosmic rays impinging on earth’s atmosphere collide with theatmospheric nuclei and generate numerous electrons, mesons andgamma rays. The secondary particles produce a further generation ofparticles, along their pass in the atmosphere. The whole “track” of theevent is called an “Air Shower.” A high energy cosmic event at 10²⁰ eVgenerates 100 billion particles, that strike the ground within a 3 km
radius.
An electron in an air shower excites nitrogen molecules inatmosphere, which instantaneously emit numerous ultraviolet
fluorescence photons along the track. JEM-EUSO captures this light byremote-sensing, and images the motion of the track every few
micro-seconds (millionths of a second) as an extremely high-speed
digital video camera. The rise and fall of light signal intensity along adownward air-shower trajectory records the energy and the incoming
direction of the cosmic ray event.

Aperture exceeds AGASA's
by over 1,000 timestSpace

JEM-EUSO will be deployed
at “Kibo” (JEM) of ISS, orbiting
earth every 90-miniutes atabout 400-km in altitude.

Watch*10²⁰eV : 16 Joules of energy that can heat 1 cc of water by About 4°C

PuzzleLeap

Japan Experiment Module“Kibo” (JEM)

An interesting discharge:
Carrot Sprite phenomenon.
Photo provided by Koji Ito(Suginami-ku, Tokyo).