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Saltdome Shower Array: Simulations

Saltdome Shower Array: Simulations. Peter Gorham University of Hawaii at Manoa. salsaMC.c Simulation approach. 2.5 km cube, 12 x 12 strings with 12 nodes each, spacing 225m Cubic array, cartesian coordinates--fastest for prototyping, vector operations simplified

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Saltdome Shower Array: Simulations

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  1. Saltdome Shower Array: Simulations Peter Gorham University of Hawaii at Manoa P. Gorham, SLAC SalSA workshop

  2. salsaMC.c Simulation approach • 2.5 km cube, 12 x 12 strings with 12 nodes each, spacing 225m • Cubic array, cartesian coordinates--fastest for prototyping, vector operations simplified • Use earth density shell model, integrate along all neutrino tracks • Charged & neutral current cross sections, three flavors, EM and hadronic treated separately, Alvarez et al LPM parameterization used • No secondary brems or photonuclear interaction yet • No importance sampling--pure brute force monte-carlo integration of the volume and acceptance by counting ratio of detected interactions to total neutrino tracks started • Interactions must hit 5/8 antennas on node, and 5 nodes (thus 25 total antennas at 2.8 sigma each) --this is a conservative requirement to ensure tracks can be reconstructed P. Gorham, SLAC SalSA workshop

  3. Antenna array Saltdome Shower Array (SalSA) concept Salt domes: found throughout the world Qeshm Island, Hormuz strait, Iran, 7km diameter 1 2 3 Depth (km) 4 • Halite (rock salt) • La(<1GHz) > 500 m w.e. • Depth to >10km • Diameter: 3-8 km • Veff ~ 100-200 km3 w.e. • No known background • >2p steradians possible 5 Isacksen salt dome, Elf Ringnes Island, Canada 8 by 5km 6 7 • typical:50-100 km3 water equivalent in top ~3km • ==>300-500km3 sr possible P. Gorham, SLAC SalSA workshop

  4. Strawman array scale compared to salt dome • Strawman array (2.5km cube, 12 x 12 strings, 12 nodes per string--8 shown) easily fits into Humble dome (for example) P. Gorham, SLAC SalSA workshop

  5. Choice of antenna spacing • La = 250m (solid), 900, (dash-dot) • 250m assumed in sims • 225m spacing used gives threshold of ~50-100PeV with good detector efficiency • 2.8 sigma in 5/12 antennas in “node” trigger gives negligible thermal noise P. Gorham, SLAC SalSA workshop

  6. Basic array geometry simulated • A 2.5 km3 array with 225 m spacing, 122=144 strings, 123=1728 antenna nodes • 12 antennas per node, dual polarization (6 dipoles, 6 slot-cylinders) • ~300 km3 sr at 1 EeV • Threshold 1017 eV, few 100s antennas hit at 1 EeV, >1000 hits at 10 EeV • Rate: at least 10 events per year from rock-bottom minimal GZK predictions P. Gorham, SLAC SalSA workshop

  7. SalSA simulations: 1e18 eV event • Event near bottom of detector • Truncated bottom Cherenkov cone evident • Several dozen nodes hit cleanly (several hundred antennas) P. Gorham, SLAC SalSA workshop

  8. Event example, 1e19 eV shower • Event near top of detector • Truncated upper Cherenkov cone clearly evident • several hundred nodes and several thousand antennas hit P. Gorham, SLAC SalSA workshop

  9. Sensitivity to all GZK models • Includes all recent distinct estimates that are reasonably self-consistent • All-Iron UHECR model (Ave et al 2004) included as rock-bottom (but is not really consistent with UHECR data) • None of the models shown are yet excluded • Maximal models set parameters as high as possible consistent w/ data • 3 “minimal” models, all independent calculations • Engel et al 01 • Protheroe & Johnson 96 • Aramo et al 2004 P. Gorham, SLAC SalSA workshop

  10. Existing Neutrino Limits and Potential Future Sensitivity • RICE limits for 3500 hours livetime • GLUE limits~120 hours livetime • ANITA sensitivity, 3 flights: • 8 to 30 GZK neutrinos • IceCube & Auger estimates (based on Saltzberg 2004 Nobel symposium paper) • ~3-10 events for IceCube, 0.5-3 for Auger • SalSA sensitivity, 3 yrs live • 40-150 GZK neutrino events from conservative models P. Gorham, SLAC SalSA workshop

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