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kvi - center for advanced radiation technology

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P. Schellart

Gia Trinh

LOFAR Cosmic Ray KSP & Cosmic Lightning Project

O. Scholten, S. Buitink, A. M. van den Berg, A. Corstanje, U. Ebert,

J.E. Enriquez, H. Falcke, J.R. Hörandel, A. Nelles, P. Schellart , J. P. Rachen,

C. Rutjes, L. Rossetto, S. Thoudam, S. ter Veen

Circular polarization of radio emission from

air showers in thunderstorm conditions.

LOFAR Science Workshop

April 5th – 6th, 2016

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kvi - center for advanced radiation technology

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Fair weather vs thunderstorm

Linear polarization

P. Schellart , T.N.G. Trinh et al.

(PRL 114, 165001)

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kvi - center for advanced radiation technology

Fair weather vs thunderstorm

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Intensity footprint

ID 83687299

zenith 24 deg

325 antennas

𝝌𝟐/ndf = 3.1

S. Buitink et al.

(PRD 90, 082003 (2014)) P. Schellart, T.N.G. Trinh et al.

(PRL 114, 165001)

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kvi - center for advanced radiation technology

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Structure of E-fields

𝑬⊥𝒃𝒆𝒍𝒐𝒘

𝒉𝒂𝒃𝒐𝒗𝒆

𝒉𝒃𝒆𝒍𝒐𝒘

𝒉

𝑬⊥ 0

𝑬⊥𝒃𝒆𝒍𝒐𝒘 = 𝒌𝑬⊥𝒂𝒃𝒐𝒗𝒆

𝑬⊥𝒂𝒃𝒐𝒗𝒆

𝒗

Ea

Eb

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Circular polarization

O. Scholten et al. in prep (2016) T.N.G.Trinh et al. in prep (2016)

Small, vanish at the core Large, finite at the core, change sign

(Charge excess) (Change in the current’s direction)

Fair weather vs thunderstorm

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M. Stolzenburg et al.,

Geophys. Res. Lett. 34 (2007) L04804

Circular polarization in

thunderstorm conditions

T.N.G.Trinh et al. in prep (2016)

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kvi - center for advanced radiation technology

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Full polarization – Stokes parameters

Intensity: I

Linear polarization angle: 2 φ =atan(U/Q)

NEW: Circular polarization = V/I

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Evidence for more details

I

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Evidence for more details

Q, U I

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Evidence for more details

Full set of Stokes parameters more details about

the structure of E-fields

V Q, U I

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𝑭𝟏

𝑭𝟑

𝑭𝟐

h1 = 8 km

h2 = 5 km

h3 = 2 km

F1 = 20FL

~ 50 keV/m

k = 0.3

Xmax = 770 g/cm2

𝒉𝟑

𝒉

𝑭⊥ 0

𝒉𝟐

𝒉𝟏

3 layered E-fields

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Fitting Q, U, V

T.N.G.Trinh et al. in prep (2016)

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kvi - center for advanced radiation technology

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- Observe large circular polarization in thunderstorm

events.

- Related to the change in the transverse current.

- Get more details about E-fields when using full set

of Stokes parameters.

Conclusion