1. Design of the LORD Experiment and Perspectives of Ultra-High Energy
Particles Observation
G. A. Gusev, V. A. Chechin, B. N. Lomonosov,
N.G.Polukhina, and V. A. Ryabov.
P. N. Lebedev Physical Institute, Russian Academy of Sciences
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2. Outlook of Presentation
Problems of ultrahigh-energy cosmic rays and neutrinos observation.
LORD space experiment and design of apparatus
The results of Monte Carlo simulation
Conclusion
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3. The Main Goal of the LORD Experiment
The primary goal of the LORD experiment is the detection of ultrahigh-energy cosmic rays and neutrinos.
An investigation of the nature and spectra of cosmic particles with energies E ≥ 1020 eV (“ultra-high energies”, UHE) is one of the
“hottest” problems of modern science.
Information on these particles is important for solving fundamental problems of astrophysics and particle physics relating to cosmic ray sources and acceleration mechanisms, nature of dark matter, and space-time structure.
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4. Brief Description of the Main Goal of the LORD Experiment
Currently we have a very controversial and paradoxical situation in UHE region.
We know neither the nature of UHE particles, nor their sources or processes where they were accelerated to such extremely high energies.
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5. Experimental Results are Contradictories
Moreover, the many facts of the experimental observations at different CR detectors contradicts to the current understanding of the Universe, because a flux of these energetic particles must be suppressed, owing to the GZK CR spectrum cutoff (EGZK ≈ 7∙1019 eV) caused by the interaction with microwave cosmic background.
For resolving these contradictions, new independent measurements are necessary.
HIRES – AUGER controversy?
astro-ph
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6. Neutrino Fluxes from Astrophysical Sources and the Decay of Super-massive Particles
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7. Neutrino Fluxes in the Top-down Decay Scenario of X-particles
Barbot C, Drees M, Halzen F, Hooper D Phys.Lett. B (2003); hep-ph/
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8. The Radio Method for Detection Ultrahigh-energy CRs and Neutrinos
The idea of the radio method dates back to the paper by Askaryan, who showed that the propagation of high-energy cascades is accompanied by coherent Cherenkov radio emission. The development of cascades at high energies is determined by pair production and bremsstrahlung in the Coulomb field of charge-symmetric atomic nuclei. However, a significant number of shower particles have energies below some critical value (Ec ≈ 73 MeV in ice) at which the electrons of the medium also become a target for the interactions
A combination of these processes gives rise to shower charge asymmetry. As follows from calculations, this excess of negative charge in the shower is ~20–30% of the total number of electrons. The electrons of the excess with energies above the Cherenkov threshold emit electromagnetic waves in a wide wavelength range.
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9. The Radio Method for Detection Ultrahigh-energy CRs and Neutrinos
The application of the radio method is especially appropriate at ultrahigh energies since the power of coherent radio signal increases as a square of the shower energy.
The most important advantage of the radio method is the possibility to scan over huge volumes of radio-transparent media providing detection of rare ultrahigh-energy events with relatively high statistics.
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10. The Radio Method for Detection Ultrahigh-energy CRs and Neutrinos
Currently radio method is used as the basis for a number of experiments and projects on the ultrahigh-energy particle detection in such radio-transparent media as the atmosphere, salt domes and ice sheets of Antarctic and Greenland.
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11. Current Initiatives on UHECR and UHEN Radio Detection
Ice:
RICE - ongoing, started in 1996
FORTE, was active in 1997—1999
ANITA – ongoing
Salt:
SALSA – proposal (testbed)
SND – proposal (testbed)
Moon:
KALYAZIN (suspended)
GLUE was active in 1998
LORD – proposal 2004, now under construction
EAS: LOFAR - ongoing
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12. Sketch of LORD Experiment
Cosmic rays, neutrino interact with regolith and produce coherent Cherenkov radiation pulse, which after refraction on the Moon surface goes out to vacuum. It can be observed by satellite apparatus, amplitude, polarization, frequency spectrum being measured.
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13. LORD Space Experiment Height of orbit – 500-700 km
Spacecraft
Spacecraft
Moon
Moon
Height of orbit – km
Exposition Time ~ 2 years
Energy range of particles detection > 1020eV
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14. Block Diagram of LORD Detector
RF-1
Flight Payload Controller
Data Acquisition System
2 Gsps, 10 bit, x 4096 samples
Scientific instruments
Calibration
RF-2
Antenna System
27 V
Spacecraft
16 Mbyte memory
Power Supply
Commands
Data
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15. Antenna System ANTENNA SYSTEM: Two antennas + LNA
Polarization - LP & RP
200 MHz MHz
Gain ~ 7.5 dB
Length =1515 mm
Diameter= 600 mm
LNA gain ~ dB, NF~1.1 dB
Low Noise Amplifier
Low Noise Amplifier
1515 mm
1515 mm
Ø 600 mm
Ø 600 mm
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16. Low Noise Amplifier 200-800 MHz, NF=1.1 dB, Gain = 40 dB
Sw1
BPF MHz
from the antenna
to Data Acquisition
System
Sw2
Attenuator
Noise Generator
Noise Generator - ON
Antenna- ON
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17. Block Diagram of Analog Part (Data Acquisition System)
from LNA-1
to ADC-1
from LNA -2
to ADC-2
to antenna-1
to antenna-2
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18. Block Diagram of Digital Part
(Data Acquisition)
from analog 1
to spacecraft
from analog 2
2 channels:
ADC (2Gsps, 10-bit)
Buffer 4k x 10 bit (2048 ns)
Memory 16 Mbytes
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19. Electronics Box L×W×H = 420 mm ×320 mm×80 mm,
Weight= 12 kg, Power Supply = 27 V, 60 W
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20. Space Module LUNA-GLOB
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21. Monte Carlo Simulation
Registration apertures of CR and neutrino with energies 10^18-10^25 by Monte Carlo method for different targets were calculated. It was supposed, that apparatus was at the altitude 1000 km.
Monte Carlo Simulation
Electric fields of Cherenkov radio emission was calculated according to the usual Zas parameterization
Ef(μV/mMHz)=[N*ETs/Rs]sinϑsinϑc exp(-α(E)(cos ϑ- cos ϑc)2),
where N=(N0/ρ)(f/f0)/(1+ (f/f0)1.44), f0=3,3GHz, cos ϑc =1/n is cosine of Cherenkov angle, n is refraction index, ϑ is polar angle between cascade direction and radiation, Rs is distance between antenna and radiation refraction point, Ts is transmision coefficient for longitudinal polarization, E is cascade energy in TeV, f is frequency in GHz, ρ is density of the media, N0= μV/mMHz , ,
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представлено на Рис.3.

22. The Radio Signal Reflection
from the Regolith-basalt Boundary
Cascade produces Cherenkov radio emission, which propagates up and down. Up-going radiation goes out in vacuum and reflects down to basalt-regolith boundary and then reflects second time. Down-going radiation being reflected from basalt-regolith boundary goes out to vacuum. Taking into account of reflected signals is very important.
Direct radiation
Reflected radiations
Regolith, n=1,73
ν, CR
cascade
Basalt, n=3
Moon
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23. The Results of Simulation for Direct and Reflected Signals
This example shows, that there are cases, when reflected signal is short, that is its spectrum is more large, as comparing with direct signal.
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24. Direct and Reflected Pulses (Long Time-delay)
This example shows, that there are cases, when reflected signal has long time-delay relative direct signal.
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25. Middle Time-delay, Middle Amplitudes, Short Reflected Pulse
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26. Short and More Intensive Reflected Pulse
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27. Direct and Reflected Pulses (Short Time-delay), both Pulses Strong
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28. Direct and Reflected Pulses (Short Time-delay), Strong Direct Pulse and Weak Reflected Pulse
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29. CR Events on Visible Area of Moon
nadir angle
azimuthal angle
Νev=F(Θnadir, φazimut)
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Red squares – direct signals and blue ones – reflected signals

30. Integral event number as function of particle energy for CR
Detector threshold is about 1020 eV.
Integral count rate is about 320 events.
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31. Simulation of Neutrino Detection for flux of massive particle decays
Numbers of events
Mass of X-paticle 2· 1025 eV,
Satellite altitude – 700 km, Regolith layer – 2-12 m,
SNR=6 (threshold – 100 μV)
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32. Apertures CR and Neutrinos as Function of Particle Energy
Blue curve corresponds regolith, and red one – basalt. Maximum aperture for CR is 3·105 km2 sr. Maximum aperture for neutrino is 105 km2 sr.
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33. Limits for CR and Neutrino Fluxes
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34. Conclusion LORD is elaborated and now under construction.
The additional contribution of reflected signal greatly enhances the scientific potential of experiments with the lunar orbital radio detector.
LORD apertures for UHECR & UHEN detection are higher than in all ongoing experiments and for energy 1021 eV are about 3·105 km2 sr for UHECR and
105 km2 sr for UHEN
The work is performed with partial support of grant RFBR and Program of Russian Academy of Sciences “Neutrino Physics”.
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35. Expected “Luna-Globe” launch 2012
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36. Thank you for attention
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