1 / 27

The O rbiting W ide-angle L ight-collectors Experiment owl.gsfc.nasa/

The O rbiting W ide-angle L ight-collectors Experiment http://owl.gsfc.nasa.gov/. John Krizmanic USRA/NASA/GSFC Code 661 for the OWL Collaboration. The OWL Collaboration. NASA GSFC Laboratory for High Energy Astrophysics University of Utah University of Alabama, Huntsville NASA MSFC

walden
Download Presentation

The O rbiting W ide-angle L ight-collectors Experiment owl.gsfc.nasa/

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. The Orbiting Wide-angle Light-collectors Experimenthttp://owl.gsfc.nasa.gov/ John Krizmanic USRA/NASA/GSFC Code 661 for the OWL Collaboration

  2. The OWL Collaboration NASA GSFC Laboratory for High Energy Astrophysics University of Utah University of Alabama, Huntsville NASA MSFC UCLA Washington University Columbia University Vanderbilt University Rutgers University Montana State University • Outline: • Science Motivation • The OWL Concept • Preliminary OWL Simulation Results

  3. The Cosmic Ray Spectrum AGASA Spectrum N. Hayashida et al., astro-ph/0008102

  4. Airshower Basicsfor a nice primer see HiRes web page http://hires.physics.utah.edu

  5. The Mystery of the Highest Energy Cosmic Rays • Greisen-Zatsepin-Kuz'min (GZK) effect implies source must be close (< 50 Mpc) if UHECR are nuclei. • ‘Bottom-up’ acceleration to 1020 eV is difficult, and no nearby sources are evident. • Alternate hypothesis, UHECR are the result of a ‘top-down’ process, i.e. topological defects (ETD ~ 1025 eV) or Z-bursts. OWL will identify source of UHECR by extending energy reach to > 1021 eV Item ‘Bottom-up’ ‘Top-down’ Proton Spectrum Softer Harder Photon Spectrum Softer Harder (g’s are secondaries) (g’s are primaries) Neutrino Flux Softer Harder (n’s are secondaries) (n’s are primaries) Takeda et al. (1998) PRL, 81,1163 Cronin (1992), Nucl Phys B (Proc Suppl) 28B, 213

  6. A.M. Hillas, Ann. Rev. Astron. and Astrophysics (1984)

  7. 25.0 20.0 15.0 10.0 5.0 0.0 200.0 400.0 600.0 800.0 1000.0 1200.0 2 The OWL Concept Use air fluorescence technique to image 300 T 400 nm photons in ~ 0.1O pixels (with 10 ns Tms timing), from low Earth, equatorial orbit, airshowers induced by E t 1019 eV cosmic rays Wide angle (~ 60O full, FOV) optics at a 600 - 1200 km orbit in a stereo configuration T an asymptotic, instantaneous aperture ~ 3 x 106 km2-ster (640 km orbit, 60O full, FOV, ‘Old’ Baseline) 10% duty cycle Teffective aperture ~ 3 x 105 km2-ster Assuming FCR (E) ~ E-2.75, the asymptotic OWL stereo aperture leads to ~ 3000 events/year with E r 1020 eV OWL could be a stepping stone to viewing majority of night side atmosphere Eye 1 Eye 2

  8. 833.33 MM OWL/AIRWATCH Maksutov Type Telescope Scale: 0.03 DJL 17-Mar-99 Fresnel-Maksutov Optics 0.1o Pixel Angular Resolution in UV ~ 104 away from Diffraction Limit D. Lamb et al., NASA/MSFC University of Alabama, Huntsville

  9. Maksutov Mechanical Concept Alan Posey, NASA/GSFC

  10. Comparison of UHECR Experiments

  11. Modeling Procedures (Airshowers) • Basic Assumptions • Isotropic flux impinging on spherical Earth • Shibata Parameterization of Atmospheric Grammage • Standard 1976 US Atmosphere temperature profile • Fluorescence and Cherenkov includes l dependence • Shower generated and signals recorded in 1 ms steps • Mono or stereo satellite configurations modeled with ability to set satellite pitch angle, orientation(s)} • Airshower Event Generator • Employs generator developed by Paul Mikulski (USNA) which models hadronic primaries interacting with the Earth's atmosphere generating longitudinal airshowers • (see Paul's Ph.D. thesis, JHU): • A variation of the Hillas splitting algorithm • Charged pion decay and neutral pion re-interaction • A parameterization of the LPM effect • Shower starting point and development fluctuations • Shower described by 4-parameter Gaisser-Hillas function

  12. Modeling Procedures (Light Generation) • Signal Generation • Fluorescence l dependent (Bunner, Ph.D. thesis) with pressure and temperature dependence (Kakimoto et al., ICRR-Report-346-950-12) • Cherenkov light generated in 25 nm bins for 200 nm -> 600 nm. Light scattered into instrument via (Baltrusaitis et al., NIM A240) • d2N/dl dW = dN/dl 3/16p (1 + cos2(qView)) • UV Background • DC Dark sky background assumed, Fly's Eye measurement of 400 photons ms/deg2/m2 • (65 g’s/ cm2/msec/ster) assumed with model which includes reflectivity of the Earth to determine background as viewed from orbit.

  13. Modeling Procedures (Atmospheric Scattering) • Atmospheric Scattering of Light • Slant depths to instrument(s) calculated point-by-point on shower path numerically. Fluorescence and Cherenkov signals attenuated with implicit l dependence: • Rayleigh Scattering: (Sokolsky) • dNg/dx = -r (Ng/{XR)(400/l)4 • where XR =2974 g/cm2 and l in nm • Ozone Absorption: (McPeters et al.) • dNg/dx ~ exp(-0.325 k) • k = 10110.5 - 44.21 logl (atm-cm)-1 and l in nm • Effects not presently included: • Mie (aerosol) Scattering: At Earth's surface ~ exp(-h/h0) with h0 ~ 1 km • Clouds, volcanos, fires, etc • At this point, the UV signal has been transported out of the atmosphere and delivered to the instrument.

  14. Model Procedures (Instrument, ‘Old’ Refractive Baseline) • Basic Assumptions • Wide FOV Fresnel Optics with 4.9 m2 Optical Aperture (Lamb et al,, AIP 433) • BG-1 UV filter • Bi-alkali photocathode (Philips PMT Data Handbook) • Light spot size assumed Gaussian with RMS diameter ~ 8 mm (f(qView)) • Pixel size of 0.1o (1.16 cm) assumed, relative position mapped from viewed • Relative shower position (in angular pixel of 0.1o and translated appropriately. • PE signal calculated from 3 x 3 pixels centered on signal pixel. Gaussian spot is integrated for each pixel assuming a 95% live area and Poisson fluctuated. • Trigger formed by summing 3 x 3 pixel response

  15. OWL Proton Aperture 640 km Orbits, 2.5 m Optical Aperture, ‘Old’ Baseline

  16. UHE Neutrinos via Air Fluorescence OWL Neutrino Workshop held at UCLA, Nov. 1999 see astro-ph/0003459 • Large Aperture (1012 tons of effective atmospheric target) opens the door for observing ultra-high energy neutrinos interactions • Horizontal Airshowers initiated deep (> 1500 g/cm2) in the atmosphere provide a signature of neutrino interactions which are well-separated from hadronic and electromagnetic showers, ln ~ 1010 cm, lp ~ 104 cm • (Air, STP, E = 1020 eV)

  17. Ultrahigh Energy Neutrino Physics _ scc(nN) =scc (nN) = 5.5 x 10-36 (En / 1 GeV)0.363 , En > 1016 eV nlN fi l-X ds/dxdy ~ Q(x) + (1-y)2Q(x) nlN fi l+X ds/dxdy ~ Q(x) + (1-y)2Q(x) _ _ _ C. Quigg, FERMILAB-Conf-97/158-T <El> ~ 0.8 En at En = 1020 eV Ghandi et al., Phys Rev D 58, 093009

  18. Neutrino Induced Airshowers • For UHE neutrino-quark interactions at 1020 eV, • <El> ~ 0.8 En -> <EHadrons> ~ 0.2 En • Leptonic induced airshower properties: • Electron: Electromagnetic Shower • Muon:ECritical ~ 1 TeV • Tau:ECritical ~ 1 PeV, ct = 87 mm -> For Et = 20 EeV, g ct = 1000 km Stanev and Vankov, Phys Rev D 40 (1989)

  19. OWL Electron Neutrino Aperture 640 km Orbits, 2.5 m Optical Aperture,’Old’ Baseline For UHE nl N -> l N’, on average 80% En deposited into lepton. For UHE ne N -> e N’, 100% En deposited into airshower

  20. VHE and UHE Neutrino Flux Predictions 1 Stecker &Salamon, Space Sci Rev 75 (1996) 2 Stecker, Done, Salamon, &Sommers, PRL 66 (1991) 3 Sigl, Lee, Bhattacharjee, & Yoshida, Phys Rev D 59 (1998), mX = 1016 GeV, X -> q+ q, SuperSymmetric fragmention 4 Yoshida, Sigl, & Lee, PRL 81 (1998), mn = 1 eV, Primary Fn ~ E-1 5 Waxman and Bahcall, PRL 78 (1997)

  21. OWL Preliminary Electron Neutrino Event Rates 640 km Orbits, 10% Duty Cycle, 2.5 m Optical Aperture, ‘Old’ Baseline 1 Stecker, Done, Salamon, &Sommers, PRL 66 (1991) 2 Sigl, Lee, Bhattacharjee, & Yoshida, Phys Rev D 59 (1998), mX = 1016 GeV, X -> q+ q, SuperSymmetric fragmention 3 Yoshida, Sigl, & Lee, PRL 81 (1998), mn = 1 eV, Primary Fn ~ E-1

  22. Tau Neutrino Regeneration • The diameter of the Earth becomes opaque to neutrinos for E > 40 TeV • However, tau neutrinos traverse the Earth albeit with degraded energy due to regeneration (Halzen & Saltzberg (1998), PRL 81) • This effect opens the possibility to perform a cosmological long-baseline muon -> tau neutrino oscillation appearance experiment. • Directional Cherenkov radiation from upward airshowers T ~ 1015 eV threshold neutrino energy

  23. Upward Airshower Flux Sensitivity The Earth's crust is a huge neutrino target (1 km3 of ice ~ 1010 ton-ster n Aperture)

  24. OWL will measure the UHECR spectrum (1020 -> 1022 eV) • Predicted Cosmic Ray Event Rates E > 1020 eV • (assuming continuation of spectrum) • 1000 Events/Year (1 satellite) • 3000 Events/Year (2 satellites) • 300,000 Events/Year (Whole Dark Earth, N satellites) and explore UHE Neutrino Astroparticle Physics • Measurement of the UHE CR flux via pg2.7K • Cosmological long-baseline nt appearance experiment • Detection of relic 1.9K neutrinos via ZBursts • Detection of the GUT scale via topological defects • Detection of neutrinos from GRB’s • Cross Section Measurements: Anomalously high values could be signature of a new physics scale (Domokos & Kovesi-Domokos, PRL 82 (1999); Carena et al., hep-ph/9804380 (1998) • ?????

  25. OWL Mission Status • OWL Mission Study Proposal Accepted in 1996 • Study during 1996 - 1999 deemed feasibility of mission • UHE Physics Workshop held in November 1997 • UHE Neutrino Workshop held at UCLA, 1999 • OWL Roadmap Workshop held at University of Utah, 2000 • UHE Physics Workshop held at NASA GSFC, 2000 • OWL is in NASA’s SEU Mid-term Strategic Plan • Proposals submitted to NSF in 2000 • Italian AirWatch group summits EUSO proposal to ESA in 2000 • Phase A accommodation study on ISS approved • OWL working to advance to NASA’s Near-term Strategic Plan

  26. NIGHTGLOW: UV Night Sky Background Measurements http://lheawww.gsfc.nasa.gov/docs/gamcosray/hecr/NightGlow/ng.html

More Related