Transcript STUDY OF ULTRA HIGH ENERGY COSMIC RAYS: TOWARD …

SPACE DETECTORS TUS and KLYPVE for
STUDY of ULTRA HIGH ENERGY COSMIC
RAYS
TALK AT THE INTERNATIONAL SEMINAR ON
ULTRA HIGH ENERGY COSMIC RAYS
14 APRIL 2005
B. A. KHRENOV
D.V. Skobeltsyn Institute of Nuclear Physics
of the Moscow State University, Moscow, Russia
How Extensive Air Showers are measured
10
1 10
N1( Ep , x )
9
5 10
N2( Ep , x )
0
0
500
1000
1500
x
EAS cascades for primary energy 1018 eV.
Red curve- primary iron nuclei.
Dotted blue- primary proton.
Extensive Air Showers (EAS) give
information on Cosmic Rays
starting from energies 1014-1015 eV.
At energies more than 1018 eV the EAS
atmosphere fluorescence is measured along
with the particle flux and the Cherenkov
light.
Fluorescence
Detector
Particle or Cherenkov
detectors
The isotropic fluorescence radiation could
be measured from space - from satellites.
The innovative technology of space
fluorescence detectors is in progress.
Methods of the EAS primary energy measurement
Successfully working methods:
1. Charge particle (electron) size. Integral over the
experimental lateral distribution. Core distances ~100 m.
2. Charge particle density at large core distance ~600-1000 m.
3. Air Cherenkov radiation flux in air (in water).
4. Atmosphere fluorescence signals (cascade curve, signal at the
EAS maximum).
Other methods, less certain :
1. Radio signal, radiated by EAS (Cherenkov, geo-magnetic
mechanisms) in air, in ice.
2. Acoustic signals in ice and water, in the Moon ground.
3. Radio echo from the EAS core.
Scientific Problem - Origin Of The Ultra High Energy
Cosmic Rays (UHECR)
Experimental data of AGASA are against the GZK Cosmic Ray cut off.
Data of HiRes confirm the cut off. Yakutsk data agree with the HiRes
data. Detectors of the next generation should solve the problem.
What is the cut off?
P+γ=P+hadrons Eγ=2Eph Ep /Mp c2
Eph =2.5 10-4 eV (T=2.75K)
In proton rest frame photon energy Eγ >100
MeV for Ep >1020 eV. ρph =500 cm-3
Cross-section of interaction is σ=10-28 cm2
Interaction free path L=1/ σ ρph =70 Mpc
G.T. Zatsepin (1967)
Greisen-Zatsepin-Kuzmin
made the first estimates of
the effect and find the energy
limit for protons
EGZK =5x1019 eV.
Arrival direction of UHECR particles over the Northern hemisphere.
Red squares- E>1020 eV, green points- E=4-10 1019 eV. Dublets and
triplets (events from the same coordinates in sky in errors of 2.5o) are
blue and violet circles. Galactic (red) and Supergalactic (blue) planes
are presented as curves.
Possible sources: astrophysical accelerators, the objects with the relativistic shocks.
The alternative sources of EECR are the massive
particles (M~1024 eV) – relics of the Big Bang.
They might be responsible for the Dark Matter. The EECR protons (or
gamma quanta) are products of their decay.
The EECR particles registered by AGASA in this interpretation indicate
the Dark Matter of our Galaxy.
Topological defects are the other theoretical source of the massive particles
decaying to EECR particles.
The experimental separation of photons from protons in EECR
is the key point in a search for massive particles, producing
mainly photons in final decay generation. AGASA data on the
muon to electron ratio in EAS of the highest energies are
against the photon origin of primaries.
0.5
H
Ground based fluorescence detector has a problem of
fluorescence light absorption in a horizontal view.
0
30
Absorption length La as a function
of the fluorescence wavelength
at sea level.
La is the result of the Rayleigh
scattering. Sometimes scattering
on aerosols makes Lreal<<La.
20
La( H   )
10
0
300
350
400
450
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H
0
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3 60
1
At horizontal distance r~30 km to
the EAS disc the fluorescence
photon intensity decreases by 10
times due to Rayleigh absorption .
Aerosol absorption may make it
order of magnitude less.
R a( H    l ) 0.5
0
0
20
l
r 40
The space fluorescence detector looking to the atmosphere from a larger
distance (400 km) should have larger light collection mirror but it has
advantage of low light absorption in the atmosphere.
This advantage makes it possible to have reliable EAS fluorescence signals
in the detector with a comparatively small mirror: ~10 m2 .
x1
Percentage of light escaping
the Rayleigh
scattering in the
atmosphere (vertical
direction).
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1 03 0
3 10 3 11 4 00
0.8
0.6
 ( x1  )
0.4
0.2
300
350
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400
The inclined EAS’s (zenith angles
>50o) are developed high in the
atmosphere, above the clouds,
where the atmosphere is highly
transparent and stable.
The Cherenkov light scattered from
the clouds at reference height provides
the absolute scale of height in the
atmosphere for observation from a
satellite.
The cloud height has to be measured
by a special device (Lidar) immediately
after the EAS event registration.
In 1980 Prof. John Linsley suggested to put the
fluorescence detector into space and look down to
the Earth atmosphere. He called this experimental
concept - “Airwatch”.
He initiated two parallel space projects: wide angle
optics (OWL, EUSO) and large mirror optics (KLYPVE,
TUS).
In 2000 at the Lodz European
symposium he gave a talk “Beyond
the GZK horizon” stressing the point
of detection of EAS, generated in the
atmosphere by the secondary
(cosmological) neutrino with energy
threshold of 10 EeV. At that time
only KLYPVE project with 10 m2
mirror was being developed to
register such a “low” energy EAS.
KLYPVE is a narrow FOV detector (“telescope”) with
a large area mirror-concentrator. What advantages
the telescope has compared to the OWL-EUSO
wide FOV detectors?
1. Large mirror makes possible to detect UHECR already measured
with the ground-based detectors (calibration of the space detector
method).
2. When mirror area is enlarged up to 100 m2 (energy threshold
3EeV), the telescope observing the area of 104 km2 will let us
measure the anisotropy of CR in the energy range 3-10 EeV where
the transition from Galactic to extragalactic origin is expected .
3. Low energy threshold will help to look beyond GZK horizon
registering “cosmological” neutrinos.
4. Development of the large mirror-concentrator technology is of great
interest for space researches. A reliable, large area mirrorconcentrator is easier to construct than the complex lens optics.
5. For example, when the mirror area is enlarged to 1000 m2 , it will be
possible to register EAS and other optical flashes almost at the
whole atmosphere disc with a telescope in a geostationary orbit.
1000 m2 telescope at the geostationary orbit. Mirror diameter 30 m,
resolution 16 arc sec (3 km in the atmosphere). Energy threshold
1020 eV. Observed area 3x107 km2.
How to build a large mirror-concentrator in space?
There were many suggestions:
1. Standard segmented parabolic
(spherical) mirror.
2. Inflatable concentrator.
3. Fresnel “high frequency” mirror.
4. Fresnel “low frequency” mirror.
We have chosen the option of the
segmented “low frequency”
Fresnel mirror.
Our Cosmic Ray
experimental device
is an additional payload
in the planned ROSCOSMOS
missions.
Our device has to be compact in transportation mode.
Spot size of the mirror for various ring algorithms.
Design of the segmented mirror- concentrator
consisted of 37 carbon- plastic segments of
the low frequency Fresnel mirror.
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The mirror- concentrator mass
is less than 50 kg for the mirror
area of 10 m2.
Accuracy in mirror ring profiles
 0.01 mm.
Stability of the mirror
construction in the temperature
range from
–80o to + 60o C.
The mirror development
mechanism makes the mirror
plane with the angular
accuracy less than 1 mrad.
The first mirror telescope is an additional payload at
the RESURS DK-1
mission (planned to be
next after the Pamela
experiment).
The TUS (Tracking
Ultraviolet Set Up)
detector registers an EAS
track from the Space
Platform.
The light collector and
photo detector are
highlighted in red.
The other option of the
TUS accommodation
on the next RESURS platform:
Resurs O.
2 ТUS telescopes register the
EAS track from Resurs O.
Independent registration by
two telescopes will allow to
check errors in the EAS
parameters.
Photo receiver concept:
1. The pixel size at the atmosphere has to be 1-3 km
(a compromise between needed 1 km resolution and
economical number of pixels).
2. For large mirror diameter with a focal distance equal
to the diameter (condition of small aberrations) the
pixel size in the focal plane is rather large (>1cm) and
a single PM tube (not the multi-anode tube) is the best
photo sensor.
3. Pixel photo sensor has to be robust, operating linearly in
wide range of the atmosphere luminosity (moon nights included).
4. Photo sensor should be stable in at least 3 years of operation
in space.
Photo sensor: 1.reflecting light guide 2. PM tube
3. Raw of sensors with the electronic board (4) under it.
6. The photo receiver box covered by UV filter (8) and
the blend 7 (protection from side light).
Concept of the UHECR registrationmany channel digital oscilloscope
Example of the EAS, “registered” by the telescope
E0=100 ЕeV, θ0=75°, φ0=25°,
Moonless night; σE0/ E0 ~ 10 %,
σθ0 ~ 1.5°, σφ0 ~ 1°.
Organization of work on the space UHECR telescopes.
Russia team.
ROSCOSMOS - the Operator.
SINP MSU- the Leading Institution.
Participants:
JINR (Dubna)
RSC “ENERGIA”, Consortium “Space Regatta”.
Samara “PROGRESS” Construction Bureau.
KOSMOTEPETL COLLABORATION.
Russian team
Mexican Universities: Puebla (BUAP), Michoacan.
Korean University (Seoul).
The first TUS telescope parameters
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Area of mirror-concentrator- 1.4 m2
Focal distance
- 1.5 m
Pixel number
- 256
Pixel size (FOV)
- 1.5 cm (0.01 rad)
Detector FOV
- 0.16 rad
Time sampling from
- 800 ns
Wave length range
-300-400 nm
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The TUS detector on board
of the Resurs DK1
Two TUS detectors on board of the
Resurs O.
Steel press-forms for production of carbon plastic
mirror replicas (JINR).
The first mirror segment sample- replica of the mold.
The mechanism of mirror development
is designed (Consortium Space Regatta)
In this mechanism one electric motor moves the segments
via axles and Cardan joints.
The TUS photo receiver prototype:
4x4=16 PM tubes. It was tested in the Puebla
University (Mexico).
TUS prototypes at the Mexican mountains
Mexican Universities team with the
first TUS prototype
A view from the TUS mountain site
The TUS Project Scientific Goals.
1. Proofing the new technology of EAS observation by the Space Detector.
2. Experimental study of the Cosmic Ray energy spectrum in the range of
energies >50 EeV with the geometrical factor not less than 3 000 кm2 sr per
year with the EAS energy threshold of 30-50 EeV.
3. A search for “exotic” EAS with Xmax >1200 g/cm2 (initiated by neutrino) and
with Xmax <300 g/cm2 (initiated by relativistic dust grains).
4. UHECR anisotropy study.
5. A search for other phenomena of UV atmospheric flashes.
6. Testing the TUS mirror-concentrator design in view of using it for
construction of large area mirrors in space (up to 100 m2 ).
Energy spectrum of EECR expected as a result of the TUS operation in
2 years. 1- as predicted by data of Yakutsk and HiRes, 2- as predicted by
data of AGASA.
Expected distribution of EAS maximum positions for various primaries.
1- relativistic dust grain, 2- iron nucleus, 3- proton, 4- Fly’s Eye experimental
data for energy 1019 eV, 5- neutrino.
The TUS type UV detector at the MSU “Tatiana” satellite
UV detector comprises 2 PM tubes
(one tube measures the charge particle
background) and electronics block.
Detectors on the micro satellite.
Goals in 2005: Testing the PM tubes and the TUS type
electronics. Measurement of the atmosphere UV background
in short time samples (0.1 msec).
Measurements of aurora lights, meteors, lightnings.
“Tatiana” is orbiting the Earth at
approximately circular polar orbit
with the height of 1000 km.
Diameter of the observed
atmosphere is 250 km.
Several types of UV
measurements:
1. Every 4 sec ACD measures
the PMT charge collected
in integration time 60 msec.
(measurements of UV on-route)
2. Digital oscilloscope measures
the UV flashes with time sample
16 µs (duration <4 msec).
3. Digital oscilloscope measures
the UV flashes with time sample
256 µs (duration <64 msec).
In 2 and 3 only the brightest events
are sent to the mission center
(problem of poor telemetry).
Examples of UV intensity measurements on- route.
Moonless night. A peak at right is the Japan UV lights.
The moon night. The UV intensity depends on the moon
phase and its height above the local horizon.
There is a correlation of UV intensity with the cloud regions
(preliminary analysis).
The registered range of UV intensity at the night side
of the Earth is 2x107 -3x109 photons/cm2 sec sr
Examples of short UV flashes. Below are data from 6 circulations in
one day. In two of them UV flashes are registered. Due to recording
conditions many of flashes have saturated signals.
Energy of saturated UV flashes in the atmosphere is >10KJ.
Their duration: 1-2 ms.
Geographic coordinates of the short UV flashes correlate around the
equator. In the same region the IR measurement (right panel)
indicates heavy clouds (may be thunderstorms). Looks like UV
detector registers the blue jets (discharges between clouds and
mesosphere)
The phenomenon of blue jet is
incomparably brighter than
the EAS of 100 EeV energy.
For registering blue jets the gain in the
TUS pixels should be much
less than needed for the EAS
observations.
The other phenomenon to be detected in the TUS detector are
meteors. Entering the atmosphere with the velocity of 30 km/s they
ionize the atmosphere and excites the fluorescence. Expected signal
in TUS with the “slow” digital oscilloscope is shown below:
Similar but faster signals are expected from the fast dust grains.
Dust grains, entering the atmosphere with the velocity of ~109
cm/s, are expected from the 104 year old SN’s
(Khrenov&Tsytovich, 2005).
Spectrum of the meteors over their kinetic energy.
1 - average intensity of solar meteors,
2 - expected spectrum of the extra-solar meteors,
3 - experimental points are data on extra-solar meteors
from radar measurements
Bold lines- expected
results from the TUS
telescope.
3
Bold circle - the rate
of fast grains from
old SN’s.
At the lowest intensity
(10-9) the rate in TUS is
hundred events per year.
Conclusion
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In phase A of the TUS project the segmented 1.4 m2 mirror-concentrator is
designed. The goal of this design is to construct large space mirrors with
area up to 10-100 m2 .
Electronics of the TUS photo receiver (256 pixels) is designed and tested in
operation of the Tatiana satellite. This design could be applied in
construction of the photo receiver of the next KLYPVE telescope.
The TUS telescope is able to study other phenomena in the atmosphere by
measuring fluorescence images of
-Blue jets, lightning
-Micro meteors
-Fast dust grains.
The TUS electronics is suited for registering these “slow” flashes. The TUS
triggering conditions will be controlled from the mission center.
The TUS phase B has to be started in 2006.