The Telescope Array Experiment by J.N. Matthews: Understanding Ultra High Energy Cosmic Rays

1. The Telescope Array Experiment J.N. Matthews University of Utah for the Telescope Array Collaboration ICRC – 12 August 2011 Beijing, CN

2. Telescope Array (TA) • Collaboration forged by members of HiRes and AGASA • Study Ultra High Energy Cosmic Rays (spectrum, composition, anisotropy, …) • Understand the differences between AGASA and HiRes • Study the galactic to extra-galactic transition: measure cosmic rays over the second knee, ankle, and GZK with one cross-calibrated detector • Currently, institutions from US, Japan, Korea, Russia, and Belgium

3. Telescope Array Collaboration T Abu-Zayyad1, R Aida2, M Allen1, R Azuma3, E Barcikowski1, JW Belz1, T Benno4, DR Bergman1, SA Blake1, O Brusova1, R Cady1, BG Cheon6, J Chiba7, M Chikawa4, EJ Cho6, LS Cho8, WR Cho8, F Cohen9, K Doura4, C Ebeling1, H Fujii10, T Fujii11, T Fukuda3, M Fukushima9,22, D Gorbunov12, W Hanlon1, K Hayashi3, Y Hayashi11, N Hayashida9, K Hibino13, K Hiyama9, K Honda2, G Hughes5, T Iguchi3, D Ikeda9, K Ikuta2, SJJ Innemee5, N Inoue14, T Ishii2, R Ishimori3, D Ivanov1,5, S Iwamoto2, CCH Jui1, K Kadota15, F Kakimoto3, O Kalashev12, T Kanbe2, H Kang16, K Kasahara17, H Kawai18, S Kawakami11, S Kawana14, E Kido9, BG Kim19, HB Kim6, JH Kim6, JH Kim20, A Kitsugi9, K Kobayashi7, H Koers21, Y Kondo9, V Kuzmin12, YJ Kwon8, JH Lim16, SI Lim19, S Machida3, K Martens22, J Martineau1, T Matsuda10, T Matsuyama11, JN Matthews1, M Minamino11, K Miyata7, H Miyauchi11, Y Murano3, T Nakamura23, SW Nam19, T Nonaka9, S Ogio11, M Ohnishi9, H Ohoka9, T Okuda11, A Oshima11, S Ozawa17, IH Park19, D Rodriguez1, SY Roh20, G Rubtsov12, D Ryu20, H Sagawa9, N Sakurai9, LM Scott5, PD Shah1, T Shibata9, H Shimodaira9, BK Shin6, JD Smith1, P Sokolsky1, TJ Sonley1, RW Springer1, BT Stokes5, SR Stratton1,5, T.Stroman1,S Suzuki10, Y Takahashi9, M Takeda9, A Taketa9, M Takita9, Y Tameda3, H Tanaka11, K Tanaka24, M Tanaka10, JR Thomas1, SB Thomas1, GB Thomson1, P Tinyakov12,21, I Tkachev12, H Tokuno9, T Tomida2, R Torii9, S Troitsky12, Y Tsunesada3, Y Tsuyuguchi2, Y Uchihori25, S Udo13, H Ukai2, B Van Klaveren1, Y Wada14, M Wood1, T Yamakawa9, Y Yamakawa9, H Yamaoka10, J Yang19, S Yoshida18, H Yoshii26, Z Zundel1 1University of Utah, 2University of Yamanashi, 3Tokyo Institute of Technology, 4Kinki University, 5Rutgers University, 6Hanyang University, 7Tokyo University of Science, 8Yonsei University, 9Institute for Cosmic Ray Research, University of Tokyo, 10Institute of Particle and Nuclear Studies, KEK, 11Osaka City University, 12Institute for Nuclear Research of the Russian Academy of Sciences, 13Kanagawa University, 14Saitama University, 15Tokyo City University, 16Pusan National University, 17Waseda University, 18Chiba University 19Ewha Womans University, 20Chungnam National University, 21University Libre de Bruxelles, 22University of Tokyo, 23Kochi University, 24Hiroshima City University, 25National Institute of Radiological Science, Japan, 26Ehime University

4. TA Measurements: • Spectrum • Fluorescence • Scintillator SD #1299 Thomson (Ivanov) • Hybrid #1297 Ikeda • Composition Stereo #1268 Tameda • Anisotropy • Point Sources #1311 Okuda (Tkachev) • Large Scale Structure #1317 Tinyakov • Search for Photons #1266 Rubtsov • ELS – Accelerator Calibration #1252 Shibata (17th) • Radar Detection #1314 Belz(17th)

5. Telescope Array - HE The High Energy component of Telescope Array – 38 fluorescence telescopes (9728 PMTs) at 3 FD stations overlooking an array of 507 scintillator surface detectors (SD) - complete and operational as of ~1/2008.

6. TA Fluorescence Detectors Refurbished from HiRes-I 14 telescopes@station 256 PMTs/camera Observations since ~10/2007 Middle Drum 5.2 m2 ~30km New FDs 12 telescopes/station FOV~15x18deg /ea Observation since ~11/2007 Black Rock Mesa Long Ridge Observation since ~6/2007 6.8 m2 ~1 m2

7. Typical Fluorescence Event Event Display Black Rock Mesa Fluorescence Direct (Cerenkov) Rayleigh scatt. Aerosol scatt. Monocular timing fit Reconstructed Shower Profile

8. Scintillator Surface Detectors Pre-assembled in Japan, Final Assby/testing in Delta: 2 layers, 1.25 cm scintillator, 3m2 area

9. Deployment (up to 50/day) 485 SDs: 10/2006 - 3/2007

10. Scintillator Detectors on a 1.2 km square grid • Power: Solar/Battery • Readout: Radio • Self-calibrated: m background • Operational: 3/2008

11. r = 800m Typical Scintillator Detector Event 2008/Jun/25 - 19:45:52.588670 UTC Geometry Fit (modified Linsley) Fit with AGASA LDF • S(800): Primary Energy • Zenith attenuation by MC • (not by CIC). Lateral Density Distribution Fit

12. CR Observation: Detector systems have been mostly independently operated thus far However: • Many events are observed by multiple detector systems • FD mono has ~5° resolution in ψ (angle within shower detector plane). • Adding SD information (hybrid reconstruction)  ~0.5° resolution. • Stereo FD resolution ~0.5° • Need stereo or hybrid for composition • Hybrid trigger (FD to SD) will reduce the threshold Installed 10/2010

13. Example Event from 2008-10-26 MD BR LR SD

14. MC Method • Simulate the data exactly as it exists • Start with previously measured spectrum and composition • Use Corsika/QGSJet events • Throw with isotropic distribution • Include atmospheric scattering • Simulate trigger, front-end electronics, DAQ • Write out the MC events in same format as data • Analyze the MC with the same programs used for data • Validate with data/MC comparison plots

15. Middle Drum FD Analysis • Reusing HiRes-I telescopes, just moved & reconfigured • HiRes-I telescopes viewed ~360o Azi but only 3-17o elevation - thus short tracks • Middle Drum like HiRes-II, Black Rock, Long Ridge, & PAO observes 3-31o elev. • Initially use HiRes-I reconstruction • Including FY, profile constraint, etc… • HiRes spectrum reproduced?

16. Data – Monte Carlo Comparison

17. Data – Monte Carlo Comparison

18. Data – Monte Carlo Comparison

19. MD 3-Year Energy Spectrum Monocular Energy Spectrum from Middle Drum (MD) Detector ~1/3 HiRes-1 exposure ~1 AGASA exposure • Some Constants… • 14 HiRes-1 telescopes • Data cuts and analysis is identical to HiRes-1 monocular data analysis • Using the same “average” atmospheric model (VAOD=0.04) • Differences • Telescope location • Pointing directions • Broader elevation angle coverage, longer tracks • Darker sky, Thresholds (~20%) lower than HiRes-1 • Preliminary MD spectrum in good agreement with HiRes

20. Take Home • Telescope Array has collected 3+ years UHECR data in the North • Spectrum measured by Telescope Array fluorescence telescopes in excellent agreement with the spectra from the High Resolution Fly’s Eye (HiRes) • Many other measurements

21. Ongoing…

22. Electron Light Source (40ft container) Control Room (20ft container) TA Electron Light Source @ BRM Water Cooling Unit (20ft container) 75kW Diesel Generator and Tank (8ft x 16ft) Fence (80 ft x 120 ft) 100m from FD building 50m 100 ft Access Road (400 ft) Telescope FoV limit TA Electron Light Source TA Fluorescence Telescope Building @ Black Rock Mesa

23. The Electron Light Source @ KEK - Beam Operation ‘08.Feb.22th - Dec.10th ( 89days = 716hours ) Beam Condition - Repetition~ 0.5Hz - Energy ~ 40MeV - Current 10~250pC/pulse Built in Shield room This photo was taken in ‘08.Dec.24 after removal all Shields.

24. ELS Facility in Delta, UT 2/2010

25. Absolute Energy Calibration in situ by 40 MeV electron beam fired vertically into the sky Automatically takes into account fluorescence yield (l) and detector inefficiencies Geant simulation of ELS event First Beam Shots to Sky 3-4 Sept 2010