NITROGEN MOLECULAR SPECTRA OF AIR FLUORESCENCE EMULATOR USING A LN 2 COOLED CCD

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NITROGEN MOLECULAR SPECTRA OF AIR FLUORESCENCENITROGEN MOLECULAR SPECTRA OF AIR FLUORESCENCE EMULATOR USING A LN EMULATOR USING A LN22 COOLED CCD COOLED CCD

S. Maltezos, E. Fokitis, V. Gika, P. Fetfatzis,S. Maltezos, E. Fokitis, V. Gika, P. Fetfatzis,

G. Koutelieris and E. GalanisG. Koutelieris and E. Galanis

NTUA VILLA OLMO

Physics Department, National Technical University of Physics Department, National Technical University of AthensAthens

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OutlineOutline

The Air Fluorescence Yield in UHECRsThe Air Fluorescence Yield in UHECRs

Emulator Setup of the Nitrogen FluorescenceEmulator Setup of the Nitrogen Fluorescence

Noise Tests of a LNNoise Tests of a LN22 Cooled CCD Cooled CCD

Nitrogen Molecular SpectraNitrogen Molecular Spectra

Conclusions and ProspectsConclusions and Prospects

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Fluorescence radiation Fluorescence radiation

During an EAS event: the produced secondary During an EAS event: the produced secondary charged particles (electromagnetic component) charged particles (electromagnetic component) ionize or excite the atmospheric air molecules ionize or excite the atmospheric air molecules producing fluorescence radiation after their de-producing fluorescence radiation after their de-excitation (Nexcitation (N2 2 and Nand N22

++).).

The total energy of the emitted radiation of air The total energy of the emitted radiation of air fluorescence during the EAS event is about 90 % fluorescence during the EAS event is about 90 % of the energy of the UHECR primary particle of the energy of the UHECR primary particle

The main source of the experimental The main source of the experimental uncertainty of the energy determination of the uncertainty of the energy determination of the primary particle comes from our limited accuracy primary particle comes from our limited accuracy in the air fluorescence yieldin the air fluorescence yield

ΤΤhe motivation for our recent efforts and also for this work, comes from relevant results he motivation for our recent efforts and also for this work, comes from relevant results of experimental and theoretical studies for the determination of air fluorescence yield. of experimental and theoretical studies for the determination of air fluorescence yield.

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Air fluorescence yieldAir fluorescence yield

An emulator setup we present below gave us the possibility to develop a high resolution An emulator setup we present below gave us the possibility to develop a high resolution and high sensitivity UV spectrograph which should be appropriate to record the air and high sensitivity UV spectrograph which should be appropriate to record the air fluorescence in electron beam accelerators. fluorescence in electron beam accelerators.

The spectrum of the molecular spectrum is composed of several band heads of the The spectrum of the molecular spectrum is composed of several band heads of the 2P(v2P(v‘,v“) ‘,v“) - second positive) and 1N(v‘,v“) - first negative band systems of N- second positive) and 1N(v‘,v“) - first negative band systems of N22 and N and N22

++

respectively.respectively.

( , , ) ( , ) ( , )totdep

atm D

dEdNY T p X X d

dX dX

The number of photons (mostly in UV range) detected by a fluorescence The number of photons (mostly in UV range) detected by a fluorescence telescope is proportional to the deposited energy of ionizing particles inside the telescope is proportional to the deposited energy of ionizing particles inside the field of view at atmospheric depth field of view at atmospheric depth XX, is given by the integral:, is given by the integral:

Where, Where, denotes the transmittance of the atmosphere, denotes the transmittance of the atmosphere, DDthe efficiency of the detector the efficiency of the detector

and Y the fluorescence Yield which depends on the wavelength, temperature and and Y the fluorescence Yield which depends on the wavelength, temperature and pressure.pressure.

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LNLN22 cooled CCD assembly cooled CCD assembly The high-vacuum pumping system for the The high-vacuum pumping system for the CCD cryogenic chamberCCD cryogenic chamber

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