Existing and Planned UHE Cosmic Ray Experiments GRaNDScan Telescope Array Existing and Planned UHE Cosmic Ray Experiments Bruce Dawson University of Adelaide, Australia OWL

Setting the scene - UHECR ultra-high energy cosmic rays most energetic particles known in the Universe protons, atomic nuclei macroscopic energies - up to 3x1020eV (50J) - and beyond?

AGASA experiment 6 doublets, 1 triplet within 2 deg cone Arrival directions very isotropic: galactic and extra-galactic magnetic fields scramble arrival directions, except at highest energies possible clustering of rare particles above 1019.6 eV AGASA experiment 6 doublets, 1 triplet within 2 deg cone

Possible Signal around 1018eV AGASA experiment Hayashida et al. 1999 re-analysis of SUGAR experiment Bellido et al. 2001

Extensive Air Showers we can cope with very low event rates at highest energies, EAS may contain at 1011 particles and cover tens of square kilometres at ground level

Typical measurements From measurements of an EAS we can determine properties of primary cosmic ray its energy its arrival direction an estimate of its mass (nucleon, nucleus, gamma-ray) e.g. Fly’s Eye measurement of air shower development -trend towards lighter mass (protons) above 1018 eV

Greisen-Zatsepin-Kuzmin cut-off? AGASA HiRes e.g. energy spectrum current controversy over shape of spectrum above 1019eV AGASA and HiRes observatories, each with similar exposures is there a cut-off to the energy spectrum? Greisen-Zatsepin-Kuzmin cut-off? AGASA HiRes

compilation of 30 years of measurements Bahcall & Waxman Phys Lett B566,1 (2003) compilation of 30 years of measurements some of the disagreement removed by shifts in energy calibration Clearly a need to “intercalibrate” techniques

AGASA - Akeno Giant Air Shower Array JAPAN 100 square kilometres 1992-2004

AGASA detector station 111 plastic scintillator detectors, each 2.2 square metres in area 27 also equipped with shielded muon detectors (0.5 GeV)

AGASA technique energy from measurement of scintillator lateral distribution - signal at 600m from core (somewhat model dependent) directions from fast timing - angular resolution 1-2 deg mass estimates from measurement of muon content scintillator signal muons One of AGASA’s highest energy events (2.1+0.5 -0.4) x 1020 eV

High Resolution Fly’s Eye alternative optical technique - air fluorescence air showers excite atmospheric nitrogen fluorescence yield between 300 - 400nm approx. 4 photons per shower particle per metre of track The technique has a long history…

The First Fly’s Eye - New York 1967 Greisen, Bunner et al. Sky & Telescope October 1967

Utah Fly’s Eye 1981-1993 Cassiday, Bergeson, Loh, Sokolsky et al.

Highest Energy Fly’s Eye Event this technique is calorimetric energy comes directly from integral of shower development profile (right) but challenges include atmospheric attenuation fluorescence yield (T and P dependence) detector calibration shower size peaks at 200 billion particles E = (3.2 +/- 0.9) x 1020 eV

High Resolution Fly’s Eye One of two sites 13km apart - Dugway, western Utah Collecting area in excess of 3000km2 at highest energies US/Australia collaboration

Mirror Units 2 metre diameter mirror, 256 phototubes in focal plane a total of 67 mirror units at the two sites

Typical stereo HiRes event stereo provides advantages over single-eye observations improved shower geometry two views of shower profile (energy) checks of systematics

Mono operation Stereo operation 1997- 3600 hours mono spectrum submitted, anisotropy studies ready for submission Stereo operation 1999 - some difficulties at Dugway 1500 hours similar aperture to mono 3000km2 area

Pierre Auger Observatory

Collaboration: Northern hemisphere Millard county Utah, USA Southern hemisphere: Malargüe Provincia de Mendoza Argentina Collaboration: >250 researchers from 50 institutions and 18 countries: Argentina, Australia, Bolivia, Brazil, China, Czech Republic, France, Germany, Greece, Italy, Mexico, Poland, Russia, Slovenia, Spain, United Kingdom, USA, Vietnam

The Observatory Mendoza Province, Argentina 3000 km2, 875 g cm-2 1600 water Cherenkov detectors 1.5 km grid 4 fluorescence eyes -total of 24 telescopes each with 30o x 30o FOV 65 km

Extensive Air Shower <8 km> …not to scale

Pierre Auger - a major step Need high statistics large detection area : 2 x3000 km² Uniform sky coverage 2 sites located in each hemisphere Argentina and USA Hybrid detector : surface array (water Cerenkov tanks) + fluorescence detector  Good energy and pointing resolution, Improved sensitivity to composition Energy cross calibration

The Engineering Array 2001/2 1020 eV Shower The Engineering Array Auger Campus Engineering Array 40 Surface detector stations 2 Fluorescence cameras overlooking the array

Engineering Array

Auger Surface Detectors Three 8” PM Tubes Plastic tank White light diffusing liner De-ionized water Solar panel and electronic box Comm antenna GPS antenna Battery box

Surface Detectors 1019eV proton SD water Cherenkov detectors measure muon, electron and gamma components of EAS, the latter especially important at large core distances

Surface Detector Resolution SD Angular resolution: E > 1019eV q (deg) Proton/Iron Photon E>1019eV E>1020eV 20o 1.1o 0.6o 4.0o 40o 0.5o 2.5o 60o 0.4o 0.3o 1.0o 80o 0.2o space angle containing 68% of events

Surface Detector Resolution Energy determined from fitted density at 1000m, r(1000). Conversion factor from simulations; averaged for p and Fe primaries. E > 1019 eV rms E resolution ~12% (assuming p/Fe mixture) Proton Iron photon

SD Aperture and Event Rate Eo (eV) Trig Aperture km2sr Rate per year > Eo 1018 3x1018 2200 15000 1019 7200 5150 2x1019 7350 1590 5x1019 490 1020 100 2x1020 30 Zenith < 60o, based on AGASA spectrum (Takeda et al 1998) (Zenith > 60o adds about 50% to event rate)

Auger Southern Site Hybrid reconstruction works when a shower is recorded by the surface array and at least one eye This multiple-eye design reduces our reliance on precise knowledge of atmospheric attenuation of light Mean impact parameter at 1019eV is 14.7km

N2 fluorescence: ≈ 4 photons/m m.i. part.  dE/dx filter

The completed FD building will house 6 telescope/ camera arrays

11m2 segmented spherical Schmidt mirror, 30°30°

UV-Filter 300-400 nm installed at Los Leones (Malargüe) and taking data 11 m2 mirror camera 440 PMTs corrector lens

Hybrid Reconstruction of Axis good determination of shower axis is vital for origin studies, but also vital as first step towards good energy and mass composition assignment use eye pixel timing and amplitude data together with timing information from the SD. GPS clocks in SD tanks and at FDs. Hybrid methods using one eye give angular resolution comparable to “stereo” reconstruction

Hybrid Reconstruction Quality E(eV) Ddir (o) DCore (m) DE/E (%) DXmax g/cm2 1018 0.7 60 13 38 1019 0.5 50 7 25 1020 6 24 statistical errors only zenith angles < 60O 68% error bounds given detector is optimized for 1019eV, but good Hybrid reconstruction quality at lower energy

Simulated Hybrid Aperture Hybrid Trigger Efficiency “Stereo” Efficiency Note the significant aperture at 1018eV, and the stereo aperture at the higher energies Trigger requirement: at least one eye triggering on a track length of at least 6 degrees; two surface detectors. q < 60o Hybrid Aperture = Hybrid Trigger efficiency x 7375 km2sr

“high” energy Hybrid event 170067

170067

Light received at FD Inferred Shower Profile E = 1.5 x 1019eV

Auger Schedule strong and efficient collaboration engineering array was a great success, we have recorded some beautiful events. two FD buildings have been constructed, fully instrumented by end of 2003 next 100 SD installation complete within 2 months (soon stereo-hybrid) expect full observatory complete during 2005 we hope construction of Northern Auger will begin in 2-3 years

COMPARISON OF EXPERIMENTS (Katsushi Arisaka, UCLA)

(Katsushi Arisaka, UCLA)

Telescope Array Project Japan/US collaboration. Japanese funding for Phase 1 has just been announced. A hybrid detector system 20 km UTAH, USA 24 x 24 scintillators (3m2) with 1.2km spacing (850 square km) 3 x Fluorescence stations with 120 deg azimuthal view

Scintillator Prototype: 　　　　50 cm x 50 cm, 1cm thick 　　　　　　Wave Length Shifter Fiber readout 　　　　50 modules used in L3 for 2.5 years. cutting 1.5 mm deep groove Final: 3 m2 by 2 PMT readout. WLS: BCF-91A （ 1 mm Φ ） M. FUKUSHIMA, ICRR Tokyo

Fluorescence Detector： Prototypes have been developed. M. FUKUSHIMA, ICRR Tokyo Fluorescence Detector：　Prototypes have been developed. 1 0 x 1 0 FoV / PMT 16 bit, 200 ns + DSP 3 m Φ spherical

TA Phase I Performance M. FUKUSHIMA, ICRR Tokyo Experiment Aperture (km2 sr) Rel. Angular Resolution AGASA 162 (=1) 1.60 TA: 24 x 24 ground array 1371 (9) ~1.00 TA: Fluorescence 670 (4) 0.60 TA: Hybrid Measurement 137 (1) 0.40 one goal: to intercalibrate scintillator and fluorescence techniques Phase I (2004-2009) US$15M Phase II (2010-2015): eight full fluorescence stations, effective aperture 50 x AGASA

GraNDScan GRaNDScan Does the Galactic Centre region contain a 1018 eV cosmic accelerator? Proposal for a new southern hemisphere observatory AGASA experiment Hayashida et al. 1999 re-analysis of SUGAR experiment Bellido et al. 2001

GraNDScan GRaNDScan E. Loh (Utah/Maryland), S. Westerhoff (Columbia) et al. www.nevis.columbia.edu/grandscan plan for two fluorescence sites (one movable) with particular sensitivity to 1017 - 10 18.5 eV low power electronics being developed to allow one eye to be solar powered, new micro-channel plate pmts being evaluated one possible site, Woomera, South Australia (home of CANGAROO TeV gamma-ray observatory) SEE POSTER by Gene Loh et al.

COMPARISON OF EXPERIMENTS (Katsushi Arisaka, UCLA)

one of two planned space-based observatories planned for operation in the early years of next decade ESA / NASA deployment on the International Space Station Italy, France, Germany, Portugal, Japan, USA, UK

A FLUORESCENCE OBSERVATORY Over a year EUSO will achieve full-sky coverage - important for anisotropy study

review in September, hope to commence Phase B in January Dear Prof. Dawson, Thanks for your interest in EUSO. We are currently preparing the documentation, due for the end of July, for the end of Phase A ( concetypual design) to submit to ESA (European Space Agency). We will have a review at the middle of September and we hope to get in the Phase B ( esecutive design) for the begining of the next year. You can find general information on the EUSO mission on the web: http://www.euso-mission.org If you need specific information on whatever you need, please do not hesitate to contact me. Sincerely Oscaldo Catalano

Experimental Challenges space based! mono observations - Cerenkov reflection helps atmospheric monitoring, including aerosols and clouds (lidar on ISS) UV airglow ozone absorption severe below 330nm

COMPARISON OF EXPERIMENTS (Katsushi Arisaka, UCLA)

NASA + U.S. universities

Conclusions a revived interest in the UHE cosmic rays in the past decade - since the publication of the 3.2 x 1020eV Fly’s Eye event the Fluorescence method is now a mature technique and its advantages are being recognised the future looks bright!