the mu radar experiment for searching radio …...the mu radar experiment for searching radio echoes...

The MU radar experiment for searching radio echoes from EAS

Takuji Nakamura1 ,Toshio Terasawa2, Hiroyuki Sagawa3, Hideaki Miyamoto3, y g , y ,Hideto Yoshida3 and Masaki Fukushima3

1N i l I i f P l R h1National Institute of Polar Research2Tokyo Institute of Technology

3University of Tokyo

MU radar

University of Tokyo

MU radar, Kyoto Univ.at Shigarakiat Shiga aki

Contents• Introduction

Wh t i th MU d ?• What is the MU radar?• The upgraded MU radar system (2004)pg y ( )• Observation of meteor trails

EAS h b ti• EAS echo observations– What is the target?g– Results

• Best candidate of EAS echoBest candidate of EAS echo• Less significant echo

Estimation of Energy– Estimation of Energy• Summary

Energy spectrum of cosmic rays; extending over 12 orders of energy

Origin of the ultra high ienergy cosmic rays

(UHECRs) is a long-di istanding mystery in

cosmic ray physics.

Very rare!1/1km2・century!/ ce tu y

↑1020eV↑109eV

Augerhttp://www.auger.org/news/PRagn/AGN_correlation_more.htmlEffective area 5165 km2

Now Pierre Auger Observatory is counting ~50 UHECRs in a year.

But we need more UHECRs. ….several thousands UHECRs are desirable for astrophysical study

Possible (expensive!) answer: Extreme Universe Space Observatory (EUSO)( p ) p y ( )

air shower

Possible ground-based alternative:Radio technique for UHECR detection

Passive technique … detection of geo-synchrotron emissiondetection of molecular Bremsstrahlung emission…

Active technique … radar detection of echoes from UHECR air showers

Similarity between meteors and cosmic rays (1)

‘Dust from beyond the solar system’, Nature 380, 283 (1996)

Meteors and cosmic rays are both coming from extraterrestrial spaceMeteors and cosmic rays are both coming from extraterrestrial space.

>1017 1018eV

Similarity between meteors and cosmic rays (2)

Altitude: 90-120km

Altitude: 10~20km

>1017~1018eV

Gorham(2001)

EAS

Dusts of several mm size vs. elementary particles

Similarity in total energy Similar-sized ionization

Since the radar detection of meteors is an established technique we

Similarity in total energy(several hundredths J ~ several J)

Similar sized ionization column in the atmosphere

Since the radar detection of meteors is an established technique, we should be able to apply the radar technique to cosmic ray detection.

What is the MU radar?

MU radar (middle and upper atmosphere radar) since 1984

103 m

Monostatic coherent pulse Doppler radar VHF 46 5MHz 1MW outputMonostatic coherent pulse Doppler radar VHF 46.5MHz, 1MW output Antenna aperture: 8330 m2 Beam width: 3.6 degPulse length: 1 – 500 μs

Observation height of the MU radargＭＵ radar: Middle and Upper Atmosphere radar, RISH, Kyoto Univ.

Uppery

Thermosphere

Satellite

r atmospherphereH

eig

MeteorsSodium layerM

re

Mesosp

ght (km

Middle atmp

here

m)

Ozone layer

osphere

T h

AerosolsStratosphere

Ozone layer

Troposphere

T(oC) Lidar baloon rocket MST MU ISMeteor radar radar radar radar

Target of atmospheric radar

Atmospheric radar: Coherent scatter echo

perturbation of refractive index

Incoherent scatter echo

Ionospheric electronsperturbation of refractive index (humidity, density, electron density) due to turbulence

Ionospheric electrons

Ｔ～０１ｓＴ１

Φ（δn): ------ turbulence intensity Σ σ: density of very

Ｔ～０．１ｓＴ～１ｍｓ

-------dn/dz refractive index gradient

Σ σ: density of very small scatterer

Characteristics of radar and lidar observationMeasure atmospheric parameters as a function of range

-> very good height resolution can be achieved y g g

Transmission pulse (transmitter or laser)

Propagation of light (or radiowave) (transmitter or laser)(or radiowave)

Range

Time

MU radar (middle and upper atmosphere radar)

1. Active phased array antenna (475 Yagis)beam can be steered pulse by pulse into 1657 directionsp y p

2.Flexible system design with computer controlChange of observation set-up only takes 10 sec to 1 minute.

Most capable atmospheric radar In the world.

Machine time of the MU radarFor collaborative research(1984 2006)For collaborative research(1984 - 2006)2500

大気圏標準観測電離圏標準観測一般観測キャンペーン観測保守O(h

2000

Observ

h)/Hal Mainte

nance

1000

1500

vation f Year

nance

500

1000time

r

Observation

01984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006

40

45

No.

prop 1984 Commencement of domestic collaborative

15

20

25

30

35

of posals

2005 O t I t ti l

research

0

5

10

1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006

s/HY

2005 Open to International community (2 - 4 /Half Year)

MU radar observation:Eff t f t h iEffect of atmospheric wave on

general circulation of the earth’s atmosphere

------Role of atmospheric gravity waves-----p g y----

Observation of typhoon (9426 typhoon：Orchid)

Courtesy： Dr. Yoshiaki Shibagaki (Osaka Elec-Comm. Univ.)

Cross section of tangential wind around the Typhoon 9426around the Typhoon 9426

Ctr-clockw

MotionMotion of typhootyphoonObserved wind

ClockwiMU radar Observed windRadial wind Tangential wind

MU radar

wind Tangential wind

Distance (km)Courtesy： Dr. Yoshiaki Shibagaki (Osaka Elec-Comm. Univ.)

The upgraded MU radar system(in 2004)

Upgrade of the MU radar (2004)

1984 MU radar installed Limited 4 ch1984 MU radar installed.1994 Upgrade of data taking system1997 2000 Minor upgrades

Limited 4 ch

Full 4chpg

(2001 Equatorial Atmosphere Radar in Indonesia)2004 MU ultra-multichannel digital receiver system +5 frequency d Di it l 29 hfrequency2005 International collaborative research(2-4 proposals/HY)

IT-radar system Digital 29 ch

UltraUltra--multichannel digital receiver sysrem multichannel digital receiver sysrem of the MU radarof the MU radarof the MU radarof the MU radar

1111

22 33 44 556677 88 99 1010

11115 frequency (f 46 4 )1111 1212 1313 1414 1515

1616 1717 1818

(from 46 – 47MHz)Transmission and

R i

+

1616 1717 1818 1919 20202121 2222 2323

2424Reception

Frequency domain i f f i i i2121 2222 2323

2525interferometer for imaging in radial direction (z)

Spatial domain interferometer , imaging in transversal direction (x,y)

New MU radar system is an imaging radar systemradar system

Detailed structure of turbulence layers is one of theDetailed structure of turbulence layers is one of the research target

Application of MU radar new system：Frequency Interferometer Imaging (Dr H Luce LSEET-LEPI

Time resolution: 2 minTime resolution: 32 77 sTime resolution: 32 77 sStable sheets and Turbulent structures by the range imaging

Frequency Interferometer Imaging (Dr. H. Luce, LSEET LEPI, France)

Time resolution: 2 minVertical resolution: 150 m

(=Standard observation mode)

Time resolution: 32.77 sVertical resolution: 150 mTime resolution: 32.77 sAfter Capon processingmode in the UTLS

物質輸送を司り大気環境変化の鍵を握る乱流等大気の微細構造の観測研究

Some well-organized “S” structuresbecome clearly visible after Thin layers are better resolved

application of the Capon processing

Courtesy：Prof. S. Fukao(Luce et al., 2008)

3-d imaging of quasi-periodic echo in the E-region Ionosshere (by S. Saito, NiCT, Japan)

02 June 200602 June 2006

Horizontal Images Mapped to 100 km altitude21:06:03 21:07:52 21:09:5721:09:01

war

d->

Nor

thw

EastWestVertical Images

140

tude

Vertical Images

100

Northward->

Alti

• High altitude (> 120 km) echoes.• Band (ribbon) structure aligned NW-SE drifting SW.

Northward

Observation of meteor trailsObservation of meteor trails

Meteor observation withnew MU radar receiving systemnew MU radar receiving system

April 30 – May 4, 2006Parameters

・Reception： 25 x 3-elememt crossed Yagi

・Pulse length ：0.9km （１６ bit complementary)

・IPP ：２０００μs

・Coherent integration：２

・Sample range：７０～２８０km

・On line meteor detection

Transmission beam patternPeak at 45 deg Zenith angle

25 receiving antennasRed: previous antenna set-up

Coherent output of 25 ch signalAntenna 1 Antenna 2

……. 全25出力

Power PhPhase

Time TimeTime （×4msec）

Time （×4msec）Improvement of S/N ratio by 14 dB

Meteor echo distribution03/M /200603/May/2006５０,０００ echoes /day

Local time varationRange

distribution

HorizontalEcho height Zenith Angle

Horizontal distribution

f

Angle of arrival (AOA) estimationAngle of arrival (AOA) estimation -The receiving beam is very sharpAOA candidates are searched by steering the beam in all the possible-AOA candidates are searched by steering the beam in all the possibledirections rather than using a conventional interferometer technique

dBN dB

N

３０９０W E ３０９０W E ３０９０

W E

Simulated received power S

Sp

when AOA is assumed to be zenith

An example of estimated AOA using real data

00-06 LT May 3, 2006N h d i d l i i (10 i )Northward wind velocities (10 min ave)

３００ｘ３００ｋｍ

95

9090

85

80

75

０３LT付近に小ス１００ｘ１００ｋｍ

０３LT付近に小スケールの波動が捉えられていると考えられる同時観測さ

95

90られる。同時観測された大気光観測データ（塩川、名古屋大）と比較中

90

85

80

屋大）と比較中 75

EAS echo observations

What is the targetWhat is the target

free electrons inFresnel length LF

our target 2

EAS trailg F

incoming and reflected radar waves

relativisticrelativistic electrons

at the head of EAS radar

range REAS

475 Yagi Antennas

8330m2

103103m

Frequency: 46.5MHz Peak power: 1MWAverage power: 50kWShigaraki MU radar

C d f h b k b l h d l

What is our target? ★

Condition for coherent backscattering by electrons in the ionized column of the EAS trail

EAS axis propagation directionEAS axis propagation direction

NeThe effective length of scattering region

Ionized column(number of free electons Ne～NCR*105)Expected

Waveformeof scattering region is given by the Fresnel wavelength(~400-600m). The

fWe need a fast data sampling

incident waves

EAS front passes this distance within 1~2 μsec.

sampling.

incident waves

several μsThe lifetime of free electrons is determined by the attachment process

Relativistic electrons

backscattered wavesPredicted time profile (Gorham, 2001)

Benefit of coherent scattering

y pto atmospheric oxygen molecule, and is about 1μsec （e.g.,Vidmar, 1990)

NCR

Benefit of coherent scattering:Power of the scattered wave is

proportional to Ne2.

What is our target? ★

EAS axis propagation direction Geometrical condition satisfied

condition OK

ConditionNG

～ 5%

Limitation for backscatter radarheight10～20km

Total area covered ～several hundred km2

Limitation of pulse radar

Number of CRs to be detected by the MU

pduty ratio is 5% or less

Zenith angle <~40 60 deg Number of CRs to be detected by the MU radar (0.052=1/400 of incident CRs)

>1017 eV several tens/day>1017 5 V l/d

Zenith angle <~40-60 deg

>1017.5eV several/day>1018 eV several 10-1/day>1018.5eV several 10-2/day

Shigaraki MU radar

Contents:

MU radar: system description

Trial EAS echo observation (1) dTrial EAS echo observation (1)What is our target?Range determinationDi ti fi di

done

Direction findingThe ‘best’ EAS echo candidateLess significant EAS echo candidate

Trial EAS echo observation (2)Energy estimation

Next step: Multiple transmitters + receiversRealization of multiple stations for meteor echo casep


Range determinationRange determinationDirection finding

Range determination ★

Inter-Pulse Period (IPP)＝4000μsecTransmission/Reception Timing

width64μsec

Reception ON192μsec

echo scattererΔt

0 142 334delay Δt

Δt

0 142 334μsec

0 78 272μsec

range L=ｃΔt/2y

radar

Reception ON:

From the head of the pulse: 142-334μsec (range 21.3-50.1km)

( 11 7 40 8k )

radar

Since the expected length of EAS echoes is less than pulse width,uncertainty of ~10km (±5km) is unavoidable.

From the tail of the pulse: 78-272μsec (range 11.7-40.8km)

Sampling frequency 500kHz (sampling time = 2μsec )

y ( )

Ordinary beam pattern

Transmission beam pattern Peak at 45 deg Zenith angle

Search of EAS position on the sky

Aperture Synthesis in Radio Astronomy

Direction finding

Aperture Synthesis in Radio AstronomyCorrelation between i&j antenna outputs

Fourier transformation

( Δrij =ri - rj )

1<= i, j <=25

Cij → Σ Cexp(-ikΔrij)ij=S(k)

Out of 475, 25 antennas are chosen.Signal intensity (brightness temperature)

toward the direction k

1423 directions are set in the sky area ofzenith angle θ =0-50o

0

zenith angle θ 0 50 , azimuthal angle φ=0-360o.

We calculate the brightness temperature for each direction every 2μsec. Then we search the peak of

10

20

30

40

direction every 2μsec. Then we search the peak of the brightness temperature.

(This is a time-consuming procedure. On a PC with Core2Duo 50

Zenith angle3.16GHz, it takes 2 and half hours to process the data of 20 sec duration. … factor 2h30m/20sec~450)

shows the size of antenna beam


The best candidate of EAS echoThe best candidate of EAS echo

Observations

• December 2 – 3, 2008 for 8 hours• Data analysis takes 500 times longer than

the observation timethe observation time• The survey of EAS echo candidate has

b fi h d l f h fi hbeen fished only for the first 3 hours.

5

In the panel (a), the brightness temperature (Tb) sky map for the range R=24+4.8 km

The ‘best’ EAS echo candidate

In the panel (a), the brightness temperature (Tb) sky map for the range R 24+4.8 km at 11:31:53.624 UT (02:31:53.624 LT) on 3 December 2009 is drawn. An EAS echo candidate (indicated by an arrow) was found at the direction of the zenith angle q = 12o and the azimuth angle f=185o.gThe time variation of Tb is shown in the panel (c), where the horizontal axis shows the time (ms) elapsed from the peak. A line with solid squares shows Tb at the peak direction (q = 12o , f=185o). We see that the duration of the echo was 4-6us, which is close to the duration expected for EAS echoes.We are tuning the MU system to optimize it for the detection of EAS echo candidates.

(zenith angle<50o)

Tb sky map

Echo search takes 500 times longer!

The ‘best’ EAS echo candidate

Npeak intensity~0.102008/12/3 02:32JST

synthesized map (zenith angle<50deg)

0.12

0.10 IQ_10IQ 11

Intensity time variations around the peak

bitr

ary

unit) E

peak intensity 0.10

Range: 24±4.8km0.08

0.06

0.04

IQ_11 IQ_12

nten

sity

(ar

b

0.02

0.00

3432302826242220sign

al i

# # # # # # # #8μs

N

E

Time variations of signal intensity at the peak, and surrounding points

range=24.8±4.8km

12/3 02:31:53.6 Time variation6μsec before the peakμ p

synthesized map

0 120.12

0.10

0.08

0 06

IQ_10 IQ_11 IQ_12


0.06

0.04

0.02

0 000.00

3432302826242220

range=24.8±4.8km

12/3 02:31:53.6 Time variation4μsec before the peakμ p

synthesized map

0 120.12

0.10

0.08

0 06

IQ_10 IQ_11 IQ_12


0.06

0.04

0.02

0 000.00

3432302826242220

range=24.8±4.8km

12/3 02:31:53.6 Time variation2μsec before the peak

時間変化μ p

synthesized map

0 120.12

0.10

0.08

0 06

IQ_10 IQ_11 IQ_12


0.06

0.04

0.02

0 000.00

3432302826242220

range=24.8±4.8km

12/3 02:31:53.6 Time variationJust at the peak

時間変化

p

synthesized map

0 120.12

0.10

0.08

0 06

IQ_10 IQ_11 IQ_12


0.06

0.04

0.02

0 000.00

3432302826242220

range=24.8±4.8km

時間変化

12/3 02:31:53.6 Time variation2μsec after the peak時間変化 μ p

synthesized map

0 120.12

0.10

0.08

0 06

IQ_10 IQ_11 IQ_12


0.06

0.04

0.02

0 000.00

3432302826242220

range=24.8±4.8km

時間変化

12/3 02:31:53.6 Time variation4μsec after the peak

時間変化μ p

synthesized map

0 120.12

0.10

0.08

0 06

IQ_10 IQ_11 IQ_12


0.06

0.04

0.02

0 000.00

3432302826242220

range=24.8±4.8km

12/3 02:31:53.6 Time variation6μsec after the peakμ p

synthesized map

0 120.12

0.10

0.08

0 06

IQ_10 IQ_11 IQ_12


0.06

0.04

0.02

0 000.00

3432302826242220

range=24.8±4.8km

The ‘best’ EAS echo candidate ★


synthesized map (zenith angle<50deg)ExpectedWaveform

0.12

0.10 IQ_10IQ 11


bitr

ary

unit) E

peak intensity 0.10

Range: 24±4.8km We need a fast data li0.08

0.06

0.04

IQ_11 IQ_12

nten

sity

(ar

b sampling.

0.02

0.00

3432302826242220sign

al i

# # # # # # # #8μs

N

Eseveral μs

Time variations of signal intensity at the peak, and surrounding points Predicted time profile (Gorham, 2001)

range=24.8±4.8km


Example of less significant echoExample of less significant echo

MUI.080909.020441_CR+zen.txt

BB nn hgh Rmin Rmax Zmin Zmax zan ph IQsynthMax IQsynthZen

05 422 17 16.80 26.40 13.15 20.67 38.47 216.00 1.123E-001 3.092E-003

observed image0.15

0.10

0.05

0.00

25201510１bin=2μｓｅｃ

data#range_max

range_min25 27.5km

15 17.5kmＳｈｉｄｉＳｙｎｔｈｅｓｉｚｅｄｉｍａｇｅ

MUI.080909.020441_CR+zen.txt


05 422 17 16.80 26.40 13.15 20.67 38.47 216.00 1.123E-001 3.092E-003

4 b f th t observed image0.15

4μs before the event

0.10

0.05

0.00

25201510ジ

１bin=2μ秒データ番号

Aperture synthesisにより合成した画像

最大レンジ

最小レンジ

25 27.5km

15 17.5km Aperture synthesisにより合成した画像

MUI.080909.020441_CR+zen.txt


05 422 17 16.80 26.40 13.15 20.67 38.47 216.00 1.123E-001 3.092E-003

2 b f th t observed image0.15

2μs before the event

0.10

0.05

0.00

25201510ジ



最大レンジ

最小レンジ

25 27.5km


MUI.080909.020441_CR+zen.txt


05 422 17 16.80 26.40 13.15 20.67 38.47 216.00 1.123E-001 3.092E-003

j t th t observed image0.15

just the event

0.10

0.05

0.00

25201510ジ



最大レンジ

最小レンジ

25 27.5km


MUI.080909.020441_CR+zen.txt


05 422 17 16.80 26.40 13.15 20.67 38.47 216.00 1.123E-001 3.092E-003

2 ft th t0.15

observed image2μs after the event

0.10

0.05

0.00

25201510ジ

１bin=2μ秒

最大レンジ

最小レンジ

25 27.5km

15 17.5km

MUI.080909.020441_CR+zen.txt


05 422 17 16.80 26.40 13.15 20.67 38.47 216.00 1.123E-001 3.092E-003

4 ft th t0.15

observed image4μs after the event

0.10

0.05

0.00

25201510ジ


最大レンジ

最小レンジ

25 27.5km

15 17.5km

MUI.080909.020441_CR+zen.txt


05 422 17 16.80 26.40 13.15 20.67 38.47 216.00 1.123E-001 3.092E-003

observed image0.15

0.10

0.05

0.00

25201510１bin=2μｓｅｃ

data#range_max

range_min25 27.5km

15 17.5kmＳｈｉｄｉＳｙｎｔｈｅｓｉｚｅｄｉｍａｇｅ

MUI.080909.020441_CR+zen.txt


05 422 17 16.80 26.40 13.15 20.67 38.47 216.00 1.123E-001 3.092E-003

observed image (0<θ <90)0.15

simulated image (0<θ <90)simulated image

0.10

0.05

0.00

25201510ジ


最大レンジ

最小レンジ

25 27.5km

15 17.5km Aperture synthesisにより合成した画像Aperture synthesisにより合成した画像Synthesized image for a simulated signal coming from this di ti S b kdirection. Subpeaks appearing on the sky map are due to the effect of antenna sideeffect of antenna side lobes.

Calibration of System Sensitivity


synthesized map (zenith angle<50deg)The ‘best’ EAS echo candidate

0.12

0.10 IQ_10IQ 11


bitr

ary

unit) E

peak intensity 0.10

Range: 24±4.8km0.08

0.06

0.04

IQ_11 IQ_12

nten

sity

(ar

b

0.02

0.00

3432302826242220sign

al i

# # # # # # # #8μs

N

E

Noise level (~0.0063)Time variations of signal intensity at the peak,

and surrounding points

Noise level ( 0.0063)

We estimate S/N=0.10/0.0063~16.

range=24.8±4.8kmHere noise temperature is determined by the galactic radio background, which is estimated to be ~10000K i l di th i ’ t t tincluding the receiver’s system temperature.

Calibration of System Sensitivity

Noise intensity

Pr =Signal intensity

Radar Equation

whereλ: wavelength 6.4 mgR: range (distance to EAS) 24±4.8 km …σb : radar cross section Pt: transmission power 1MW

(R24=0.8~1.2)

Pt: transmission power 1MWGt: transmission antenna gain ~1Gr: reception antenna gain ~137

Substituting appropriate values to λ, R, Pt, Gt, Gr, we have

From the observation of an EAS candidate, we have obtained Pr= 1.1×10-12 W.Finally, we obtain the estimation of the RCS,Finally, we obtain the estimation of the RCS,

d dCosmic ray energy, EAS structure, Geometrical condition for scattering

dependence

Summary• We applied a large VHF atmospheric radar (MU radar)• We applied a large VHF atmospheric radar (MU radar)

for detection of EAS radar echoes, in order to investigate echo characteristics and feasibility ofinvestigate echo characteristics and feasibility of multistatic large aperture radar observations.U i t t f t lti h l i i t EAS• Using a state-of-art multichannel receiving system, EAS echoes are scanned.F b i f b 3 h h d d• From observations of about 3 hours, we have detected one EAS echo candidate and 4 possible signals.

• The echo length was ~4us (HMFW) or less. From the observed echo power, we are trying to get the energies f h i i l ibl f hof the cosmic ray particles responsible for these

candidates.

Summary (cnt’d) – future plan• Since the echo duration is short, we will continueSince the echo duration is short, we will continue

our survey with a faster sampling rate (up to 0.5 us) with the MU radar for clarifying echowith the MU radar, for clarifying echo characteristics.

• After the investigations with the MU radar, we will design a set-up for field observations, and radar des g se up o e d obse v o s, d dexperiments with other EAS observation instruments will be carried out possibly at TA site in Utahwill be carried out possibly at TA site, in Utah.

E dEnd

the mu radar experiment for searching radio …...the mu radar experiment for searching radio echoes...

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