Radio detection of UHE neutrinos

E. Zas, USC

Leeds July 23rd 2004

EZ Leeds 2004 Radio Detection 2

Contents:

•Why UHE

•How does it work?

•What are the advantages?

•Which experiments

J. Alavarez-MuñizF. HalzenE. MarquesT. StanevR. VazquezE. Zas

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Neutrino - Cosmic Ray connection

• CR knwn to exist with E>1020 eV

• UHECR mechanisms produce • By fragmentation [“Top Down” Z-burst ...]

• By interaction [Fermi]• With matter

• With radiationInteractions with CMB => GZK neutrinos

There must be UHE neutrinos!

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The / p flux ratio: A step towards UHECR source origin

• Acceleration • Fragmentation

p+

p+p

+ 0 p

p ::

0.09 : 2 : 6

p : 1 : 6

q q X

p :0 :+/-

0.03 : 0.3 : 0.65

+

pe e+

::e

2 : 4:2

( ) ( )

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•GZK neutrino flux depends on:

•Cosmic Ray spectrum

•Source distribution

•Maximum redshift

•Source evolution

Target: The GZK -spectrum

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CR

Flu

x / R

efer

ence

Flu

x

D.Gonzalez,RAV,EZ (in prep)

p-spectrum afterCMB interactions

ONE source onlyUniform Distribution UD + strong evolution

____________

E-2

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CR

Flu

x / R

efer

ence

Flu

xE-2

D.Gonzalez,RAV,EZ (in prep)

_________U Dis+evol_________Unif Distr_________one source

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P &

-F

lux

/ Ref

eren

ce F

lux

D.Gonzalez,RAV,EZ (in prep)

_________U Dis+evol_________Unif Distr_________one source

E-2

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Radio pulses from showers: Why?

Coherent

Radiation

Radio wavelength Emission length

wl

• SIGNAL POWERElectric Field ~ Q

• STABILITYTo shower fluctuations

• INFORMATION• Spatial distribution

• Frequency Spectrum

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Cherenkov in radio (Askary’an 1960)

Wavelength (>> l,w e- and e+ cancel !!

But what about excess Ne--Ne+?

•e, interactions have charge symmetry•But matter only has electrons!!

•Interaction with matter electrons

Askary’an predicted ~10% charge excess

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Processes contributing to the excess charge

Compton e-

Annihilation

media electrons

e-

e+

Möller

e-

e-

Bhabha

e-

e+

e-

e+

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ZHS:FH,TS,EZ, PRD(91)

ICE

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)(

11)(

)()(

vki

eve

RiE

tvkiphaseoveralli

Calculate radio pulse interference

tn

tntv

)cos1(

)cos1(sin

tracklength

if =0 or =c

or t=0tv

(Fraunhofer limit)

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• |E| Ne-Ne+ Scaling

• Ne-Ne+ ESHOW

Signal Power

Radio Pulse Power |E|2 E2SHOW

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The slit diffraction analogy

If current is “thin”:

ikzezdzQR

iE )()(

cnk

)cos1(

Kind of FT with

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• c

Stability

)(zdzQE

(because k=0)

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•Calculations of UHE with hybrid code with LPM effect!!

•Electromagnetic showers ~E-1/3 above 10 PeV

•Hadronic Showers hardly any elongation up to 100 EeV

• showers measure y?

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Natural transparent media• ICE:

• Antarctica– RICE (array buried)– ANITA (balloon)

• Greenland– FORTE (satellite)

• SALT:•

Domes explored– SALSA

• MOON REGOLITH:• Radiotelescopes

– GLUE • Radiotelecope array

– LUNASKA (ska)• ATMOSPHERE:

• Antenna array– LOFAR

Coherent radio detection: -experiments

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Askary’an effect confirmed: SLAC

P.Gorham, D.Saltzberg et al. PRL (2000)

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Coherence! |E| Esh

|E()| spectral agreement

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• Radio Technique has an enormous potential• To detect highest energy events

• To get detail about showers

• To cover large surfaces

• There are many projects under consideration

• It is worth pursuing them

• It is likely that radio provides the next step in the search for UHE radiation

Summary and conclusion:

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Both Cosmic Ray & -detector

CR

Different geometries

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EZ Leeds 2004 Radio Detection 34Complex acceptance geometry

MOONJAlvarez Muñiz

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FORTE low frequency search system for transients

(weather measurements)

central :20-300 MHz bandwith: 22 MHz 5 subbands coincidences

Lehtinen, PG et al. astro-ph/0309656

Data Sep 97-Dec 99

2003 BOUND

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P. Gorham, et al. astro-ph/0310232

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GZ

K

-Flu

xE-2

D.Gonzalez,RAV,EZ (in prep)

_________U Dis+evol_________Unif Distr_________one source