# ICRC2015

July 29, 2015 to August 6, 2015
World Forum
Europe/Amsterdam timezone

## Initial results of a direct comparison between the Surface Detectors of the Pierre Auger Observatory and of the Telescope Array

Jul 30, 2015, 3:30 PM
1h
Amazon Foyer (World Forum)

### Amazon Foyer

#### World Forum

Churchillplein 10 2517 JW Den Haag The Netherlands
Board: 236
Poster contribution CR-EX

### Speaker

Ryuji Takeishi (Institute for Cosmic Ray Research, University of Tokyo, Kashiwa, Chiba, Japan)

### Description

The Pierre Auger Observatory (Auger) in Mendoza, Argentina and the Telescope Array (TA) in Utah, USA aim at unraveling the origin and nature of Ultra-High Energy Cosmic Rays (UHECR). At present, there appear to be subtle differences between Auger and TA results and interpretations. Joint working groups have been established and have already reported preliminary findings. From an experimental standpoint, the Surface Detectors (SD) of both experiments makes use of different detection processes not equally sensitive to the components of the extensive air showers making it to the ground. In particular, the muonic component of the shower measured at ground level can be traced back to the primary composition, which is critical for understanding the origin of UHECRs. In order to make direct comparisons between the SD detection techniques used by Auger and TA, a two-phase approach is followed. First, one water Cherenkov detector (“Auger North” design) was deployed and operated locally at the TA Central Laser Facility. After a couple of months of operation before the summer, we expect to observe about 20 Auger SD events in coincidence with nearby TA stations. And a regular Auger station and a TA station will be added to the setup to allow for station-level comparisons. In a second phase, event-level comparisons of relatively low-energy showers with energies in the 10$^{18}$ eV range will be possible as a result of co-locating six additional Auger North stations contiguous to TA surface detector stations. In this contribution, we present the status and prospects of this joint research project, including the first Auger SD data that were recorded in coincidence with the TA SD shower triggers.
Registration number following "ICRC2015-I/" 855 -- not specified --

### Primary author

Ryuji Takeishi (Institute for Cosmic Ray Research, University of Tokyo, Kashiwa, Chiba, Japan)

### Co-authors

B Courty (Laboratoire Astroparticules et Cosmologie (APC), Université Paris 7, CNRS-IN2P3, Paris, France) B Genolini (Institut de Physique Nucléaire d’Orsay (IPNO), Université Paris 11, CNRS-IN2P3, Orsay, France) Corbin Covault (Department of Physics, Case Western Reserve University, Cleveland OH, USA) E Rauly (Institut de Physique Nucléaire d’Orsay (IPNO), Université Paris 11, CNRS-IN2P3, Orsay, France) Fred Sarazin (Physics Department, Colorado School of Mines, Golden CO, USA) Hiroyuki Sagawa (Institute for Cosmic Ray Research, University of Tokyo, Kashiwa, Chiba, Japan) J Johnsen (Physics Department, Colorado School of Mines, Golden CO, USA) John A. J. Matthews (Department of Physics and Astronony, University of New Mexico, Albuquerque, NM, USA) Prof. John N. Matthews (High Energy Astrophysics Institute and Department of Physics and Astronomy, University of Utah, Salt Lake City, UT, USA) L Smith (Department of Physics, Case Western Reserve University, Cleveland OH, USA) Laurent Guglielmi (Laboratoire Astroparticules et Cosmologie (APC), Université Paris 7, CNRS-IN2P3, Paris, France) M Marton (Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Université Joseph Fourier, INPG, CNRS-IN2P3, Grenoble, France) Orlen Wolf (Physics Department, Colorado School of Mines, Golden CO, USA) Paul Lebrun (Fermi National Laboratory, Batavia IL, USA) Paul Mantsch (Fermi National Laboratory, Batavia IL, USA) Peter Mazur (Fermi National Laboratory, Batavia IL, USA) R Lorek (Department of Physics, Case Western Reserve University, Cleveland OH, USA) Ricardo Sato (Pierre Auger Observatory, Malargüe, Argentina) Robert Cady (High Energy Astrophysics Institute and Department of Physics and Astronomy, University of Utah, Salt Lake City, UT, USA) S Collonges (Laboratoire Astroparticules et Cosmologie (APC), Université Paris 7, CNRS-IN2P3, Paris, France) Shoichi Ogio (Graduate School of Science, Osaka City University, Osaka, Osaka, Japan) T Trung (Institut de Physique Nucléaire d’Orsay (IPNO), Université Paris 11, CNRS-IN2P3, Orsay, France) Toshihiro Fujii (University of Chicago, Enrico Fermi Institute, Chicago IL, USA) Toshiyuki Nonaka (Institute for Cosmic Ray Research, University of Tokyo, Kashiwa, Chiba, Japan)