1. P. Gorham, SLAC SalSA workshop1 Saltdome Shower Array: Simulations Peter Gorham University of Hawaii at Manoa

2. P. Gorham, SLAC SalSA workshop2 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

3. P. Gorham, SLAC SalSA workshop3 Saltdome Shower Array (SalSA) concept 1 2 3 4 5 6 7 Depth (km) Halite (rock salt) L  ( 500 m w.e. Depth to >10km Diameter: 3-8 km V eff ~ 100-200 km 3 w.e. No known background >2  steradians possible Antenna array Qeshm Island, Hormuz strait, Iran, 7km diameter Isacksen salt dome, Elf Ringnes Island, Canada 8 by 5km Salt domes: found throughout the world typical: 50-100 km 3 water equivalent in top ~3km ==>300-500 km 3 sr possible

4. P. Gorham, SLAC SalSA workshop4 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)

5. P. Gorham, SLAC SalSA workshop5 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

6. P. Gorham, SLAC SalSA workshop6 Basic array geometry simulated A 2.5 km 3 array with 225 m spacing, 12 2 =144 strings, 12 3 =1728 antenna nodes 12 antennas per node, dual polarization (6 dipoles, 6 slot-cylinders) ~300 km 3 sr at 1 EeV Threshold 10 17 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

7. P. Gorham, SLAC SalSA workshop7 SalSA simulations: 1e18 eV event Event near bottom of detector Truncated bottom Cherenkov cone evident Several dozen nodes hit cleanly (several hundred antennas)

8. P. Gorham, SLAC SalSA workshop8 Event example, 1e19 eV shower Event near top of detector Truncated upper Cherenkov cone clearly evident several hundred nodes and several thousand antennas hit

9. P. Gorham, SLAC SalSA workshop9 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

10. P. Gorham, SLAC SalSA workshop10 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