Detection of UHE Shower Cores by ANITA By Amir Javaid University Of Delaware
Topics • Rough estimates for event rate & shower core analysis summary • Detection of Shower cores by ANITA • Brief look at the shower Cores • Summary of UD Monte Carlo Simulator for Shower core detection by ANITA • Present status of UD Monte Carlo • Some preliminary results from Monte Carlo Simulator test runs • Search for a better Model for Antarctic topography • Summary and future plans
Rough estimates for event rate above 1019eV for ANITA • Air Showers For one steradian around the vertical axis the Event Rate estimated for ANITA payload horizon ~ 1.5×1016cm2from the measured cosmic ray flux data is ~1400 events per day. • Neutrinos For 2 π steradian the Event Rate estimated for ANITA horizon from the Waxman Bahcall flux model is~237 interactions per day.  ftp://ftp.bartol.udel.edu/anita/amir/EventRate_analysis_V1.4.pdf
Detection of Shower cores by ANITA • Energy in the Shower cores above 100PeV~10% (Corsika Shower Simulations) • Shower cores will produce Askaryan pulse. • Pulses may be strong enough to be detected by ANITA payload • Askaryan pulses moving downwards and reflecting back from the bed rock are the most favorable for detection • Regions with thin ice and high elevation are most suitable for shower core detection by ANITA. • Approximately 8% of the area in Antarctica has Ice thickness<1km & surface elevation >1km, which may be the region to look for shower core events
Detection of Shower cores by ANITA (contd ..) Area suitable for Shower core detection ~8% Ice thickness Histogram (Bedmap)
Brief look at the shower Cores • To analyze the properties of the shower cores a library of Corsika shower runs has been generated • Present energy span of this library is from 10PeV -1EeV • The detector elevation is set at the South Pole and zenith angle is chosen to be zero • Showers are produce in South Pole magnetic field • Flat detector and curved atmosphere model is used.
1 EeV primary proton shower footprint at South Pole for 10m2 area Brief look at the shower Cores (Corsika Simulation runs)
Brief Look at the shower Cores (contd..) 1 EeV primary proton shower footprint at South Pole for 1m2 area
Brief Look at the shower Cores (contd..) 1 EeV primary proton shower footprint at South Pole for 10cm2 area
Brief look at the shower cores (contd ..) 150 PeV ~15% of Total Shower
Present Status of UD Monte Carlo Simulator • UD MC is in testing Stage. • It is based on the SADE0.1 MC by Shahid Hussain modified to fit the ANITA event Geometry. • For testing purpose AVZ parameterized Askaryan pulses are used. • It uses Bedmap for ice thickness, bedrock elevation and surface elevation. • Interpolation is used to fill the gaps in Bedmap data. • For testing purpose Snell’s law with constant refractive of ice for ray tracing is used.
Present Status of UD Monte Carlo Simulator (contd ..) • More sophisticated ray tracing techniques do exist in UD MC. • It assumes that the ice and bedrock surfaces are flat. Perfect reflection from bedrock and perfect transmission from ice/air surface. • Point detector model with orientation. • Constant attenuation model for testing purpose. • More realistic attenuation models are also built in UD MC.
Xperp Altitude depth Rbn Preliminary Results (UD MC) Xparallel • Test Run geometry • Detector position Latitude=-79.2993 deg Longitude=-90o deg, Altitude=36986.5m • Event position & Energy Latitude=-78 deg, Longitude=-90 deg, depth=198.3m Energy=100PeV, Cherenkov Angle=55.85 deg • Test runs Red Arrows show various shower axes used to test the code Event Vertex Shower axes
Search for a better Model for Antarctic topography • For modeling of the surface and bedrock roughness much high resolution Antarctic topographical models are needed. • One option is the Radarsat Antarctic Mapping (RAMP) Project Digital Elevation Model Version 2 available from The National Snow and Ice Data Center. • RAMP 1 km, 400 m, and 200 m DEM data are provided in ARC/INFO and binary grid formats, and the 1 km and 400 m DEMs are also available in ASCII format.
Search for a better Model for Antarctic topography (contd..) Radarsat Surface elevation 400mRes Bedmap Surface elevation 5km Res
Summary and Future Plans • Development of parameterization of Askaryan pulses from shower cores. • Use of Fresnel reflection and transmission in UD MC • Realistic Detector and triggering model. • Effective area calculation • Feasibility check of the Radarsat RAMP data for the use in Monte Carlo for modeling surface roughness for bedrock and ice/air surface. These files are large (~2.5 GB), which mean more cpu cycles are required • Plan of ANITA -1 flight data analysis for shower core events.