TA-EUSO: First simulation study and status Kenji Shinozaki (RIKEN) JEM-EUSO Simulation Meeting, SASKE, Kosice 2011-Nov-3

Outline Site and concept overview Optics design, performance and goals Simulation Expected signal intensity Expected event rate Status & plan Summary

Black Rock Mesa TA-EUSO will be allocated at Black Rock Mesa FD Station Electron Light Source at 100m Most nearby SD is at ~3.5 km Central Laser Facility ~21km

Optics design (baseline on proposal) Spot size ~ 6mm (RMS) corresponding ~0.25°@~4° off axis 2PDM (~8°x8° FOV) will be mounted on FS

Field of view TA-FD station consiting of 12 telescope (ca. 10m2) triggers all event within TA-EUSO FOV Fake trigger rate ~2—3 Hz per station From TA Collaboration FD-triggger can be offered upon their approval of written agreement Further detailed data (eg. shower-detector-plane, reconstruction) is subject to their discussion

Goals Establishing functionality of PDM tested in field 2PDMs will be mount on FS Cross calibration with TA-FD Night sky Electron Light Source (corres. ~1016eV shower) Cetral Laser Facility Air shower photons Physics (using very best events) Higher resolution measurement especially lateral distribution at shower axis Concept plot ELS CLF EAS #. of photoelectron (TA-FD) TA-EUSO TA-FD ~X max TA-SD #. of photoelectron (TA-EUSO) ~ground Core distance [m] Log(#. of electrons; arbitrary)

Shower image (time-integrated) approaching shower (1) Arrival direction ZA=45, AZ=25 Landing at 10km Landing at 3km Landing at 3km Landing at 1km 10^18 eV ZA=45 degrees shower NKG-like lateral spread assumed hereafter (fluorescence only) Optics spot-size not included herein

Shower image (time-integrated) approaching shower (2) Arrival direction ZA=45, AZ=0 Landing at 10km Landing at 3km Landing at 3km Landing at 1km

Shower image (time-integrated) (overhead) receding shower Landing at 10km Landing at 3km Landing at 3km Landing at 1km

Snapshot of shower (GTU-by-GTU)

Signal intensity estimation Contours for signal intensity from EAS (E0=10^18eV, Xmax=700 g/cm2 assumed) in unit of photoelectron per gate time unit (2.5 microsec) Npe = (Ne x FY x R x A x e x cT )/4pL2 Ne: No. of EAS electron at point of interest at distance L FY: Fluorescence yield (~4 photon/m) R: Transmittance by Rayleigh scat. A: Lens aperture (=1m^2) e: Efficiency (throughput x filter transmittance x QE = 10%; assumed) T: gate time (2.5 microsec corres. 750m) Point of interest Site of telescope (H~1400 m asl) L

Estimation of number of events (E>1018eV) Optimised elevation of FOV is ~30° where ~ 100pe/GTU expected from 10km distant shower TA-FD covers 3—33° elevation that allows direct cross calibration Assuming TA spectrum (ICRC) CLASS-II event (>100pe) ~100 events / year (R~10km) CLASS-I event (>400pe) ~10 events / year (R<~3km) taking into account duty cycle ~ 10%

Best event scenario: Shower arriving behind FD site and landing in SD area Hybrid data (if available) provide shower geomery TA-EUSO observes at closer distance to resolve spatial electron distribution

Status & plan ICRC supports us in FY2011 for site survey that is planned in early 2012 along with a few Telescope Array Collaborators Kakenhi (Grant-In-Aid for Scientific Research) funds proposal submitted for 72 PMTs, travel expenses for construction and operation for FY2012—2015 Construction complete with 1 PDM is expected in Summer to Autumn 2012 to start commissioning Actual operation starts FY2013 in proposal with the fabrication of 2nd PDM in parallel It is proposed to reallocate TA-EUSO telescope to Pierre Auger Observatory after the planned project in Utah.

Summary TA-EUSO Kakenhi proposal submitted and local discussion with TA Collaborators actively started First simulations show that the current design is sufficient for test PDMs and to cross-calibrate with TA-FD using TA calibration facilities Key simulation work For ESA viewpoint, the study of lateral distribution very near shower core and the method of retrieval from observed data are needed in the time of actual operation Implementation in ESAF is also desired Optics parameters Interface to eg. CORISKA or other 3D shower simulation code including lateral distribution on the shower axis Interface to TA analysis code highly desired (if approved by TA)

Snapshot of shower (GTU=6) EAS near maximum

Snapshot of shower (GTU=9)

Snapshot of shower (GTU=12)

Snapshot of shower (GTU=13)

Snapshot of shower (GTU=14)

Snapshot of shower (GTU=15)

Snapshot of shower (inputted showers) Landing at 10km Landing at 10km Landing at 3km Landing at 3km Landing at 3km Landing at 3km Landing at 1km Landing at 1km For nearby showers, more PDMs needed Distant showers hardly distinguishable, while trigger is given by TA.