 What are Cosmic Rays? A short history What do we know now about CRs  What are Extensive Air Showers? A short history How to detect EAS? Back to CR – their energy spectrum from EAS detection  Why all these is interesting? Ultra High Energy and GZK Cut-Off Various speculations  EAS detection from the Space EUSO, OWL, TUS UHECR identification: (p, Fe, (anti) neutrino) Expected Performance  Conclusions UHECR detection from the Space PISA INFN October 2003 …by Dmitry Naumov(JINR)

Courtesy by V.Naumov

A gold-leaf Bennet-type electroscope (ca. 1880s) manufactured by Ducretet. Even very well isolated gold-leaf electroscopes are discharged at a slow rate. … observed by scientists before 1900 J.Elster, H. F.Geitel, C.Wilson investigated this phenomenon and concluded that some unknown source of ionizing radiation existed. Wilson even surmised that the ionization might be “…due to radiation from sources outside our atmosphere, possibly radiation like Röntgen rays or like cathode rays, but of enormously greater penetrating power.” Soon after, two Canadian groups, Ernst Rutherford and H. Lester Cooke (1903) at McGill University, and J. C. McLennan and E. F. Burton (1902) at the University of Toronto showed that 5 cm of lead reduced this mysterious radiation by 30%. An additional 5 t of pig lead failed to reduce the radiation further. Courtesy by V.Naumov

Victor Hess won The Nobel Prize in Physics 1936 "for his discovery of cosmic radiation". Classic references: V.F. Hess, Physik. Zeitschr. 12 (1911) 998. V.F. Hess, Physik. Zeitschr. 13 (1912) V.F. Hess, Physik. Zeitschr. 14 (1913) 610. Background of the slide: H.E.S.S. (High Energy Stereoscopic System) a next-generation system of Imaging Atmospheric Cherenkov Telescopes for the investigation of cosmic gamma rays in the 100 GeV energy range. Courtesy by V.Naumov

Up to now EAS are detected on the Earth ground Today the largest ground detector Pierre Auger in Argentina camps will cover ~3000 km 2 surface and detect both:  Charged particles  Fluorescent light

Courtesy by V.Naumov

1 st knee ~ 3×10 6 GeV GZK ~ 5×10 10 GeV ankle ~ 5×10 9 GeV 2 nd knee ~ 4×10 8 GeV Courtesy by V.Naumov

How UHECRs are accerelated? 1.Top down (TD, Big-Bang Remnants, WIMPs etc) 2.Bottom Up (shock waves, RadioGalaxies, etc) 3.Diffusion acceleration at Newtonian Shocks 4.Unipolar induction (rotating magnetic fields  strong electric field) 5.Non-linear particle-wave interaction 6.Active Galactic Nuclei and Dead Quasars 7.Neutron Stars 8.Gamma Ray Bursts 9.etc… A lot of speculation but nobody knows (and if knows does not tell us) the truth…

Isotropic distribution of CR events with energy > eV observed (Takeda et al., 1999). AGASA Super GZK event distribution. Do UHECRs come from the same Source?

2.73°K cosmic microwave background (CMB) (GZK) Cutoff What is Greisen-Zatsepin-Kuzmin CutOff ? E th > eV

A lower energy data suggests a dominance of the protons… The AGASA data seems to conflict to both Hires and GZK prediction. There is also a 2 times difference in the flux measurement between Hires and AGASA at low energies! NB: The energy threshold for the iron is about 50 times higher… Hires is a fluorescent detector AGASA is a charge track detector

Z 0 burst from the annihilation with CNB relic neutrinos in Virgo Cluster. The decay products of Z 0 are gamma rays, nucleons and neutrinos, as firmly established by the CERN LEP experiments. How do UHECRs propagate? Strong neutrino E>10 21 eV can propagate unattenuated and give us photons, nucleons and pions interacting with CNB!

Spectrum of energy Nature (p, Fe, , … ) Sources unknown! Unknown in addition : Is GZK limit is violated or no ? unknown! What do we know about UHECRs today?

Who and How is going to address the problem(s)?

Courtesy by C.Lauchaud

The Auger Observatory is now under construction. The first step consisted of 40 surface detectors (out of the 1600 for the total array) over an area of about 40 km 2 and 2 fluorescence telescopes (out of 24 for the final setup). Thirty of the surface detectors were equipped with electronics and have worked under stable conditions since January More than 70 air showers were detected in hybrid mode (seen both by the surface and fluorescence detectors), and a few hundreds of events with estimated energies above 1 EeV (10 18 eV) were observed by the surface array alone. AGASA and Hires are still collecting the data

Concept of TUS/TUS2 space free flyer 16x16 PMTs Fresnel mirror 10 rings Focal distance is 1.5 m Field of View is 7.3 o

mold production in JINR/Dubna Space qualified carbon-plastic Fresnel mirror to be “Luch” (Syzran) Mirror mold section Ring number The light spread radius on the focal plane: 90% 80% 70% Measured vs theory Measured - theory [mm]

EUSO:  ISS stationed optics  2 m diameter Fresnel lenses   30 o FoV  3 years data taking  Now end of Phase A

Same detector observing from above will see much more events: S=2  H 2 tan 2   H However there is a price for that: number of photons is much smaller! N ISS = S * /4  H 2 N emitted = S* N emitted = 10 4 ES * (E is in units eV) Thus one can not go too below in energy and can not have too small optics… There further factors: Loss in the atmosphere Loss in the detector (optics, electronics, trigger…)

UHECR Atmoshpere shower Air fluoresence Cerenkov light Reflection from the Earth Attenuation in air

Extreme Universe Space Observatory

The Background. The night view of the night we expect 500 photons m -2 ns -1 sr -1, corresponding to  0.3 p.e./  s

What if UHECRs are neutrinos?

Conclusions Whatever the scientific objectives are EUSO is a very interesting and power tool to enter the game! EUSO will collect in 3 years ~few 1000 of events EUSO will be able to separate (to some extent) p, Fe and neutrino 20-30% error for the energy measurement is expected