1. ANITA simulations
P. Gorham
5/12/2019
P. Gorham

2. My recipe
Produce a library of cherenkov rings for all events that are physically allowed and produce radio emission that escapes the surface
Use Zas Halzen Stanev, Alvarez-Muniz parametrization
Put in earth shadowing, y-dist, rf propagation, snelling
Now contains all physics except detector
Ratios of event types properly weighted
Use CR library as input to detector simulation
Account for distance to balloon
Include antenna response and thermal noise
Simulate pulse and trigger conditions
5/12/2019
P. Gorham

3. Stage 1: Cherenkov ring library
~45 deg
~30 deg
Ec = 2.5e18 eV,
0.7 deg upcoming
depth 950m
Ec = 3e18 eV
5.6 deg upcoming
100m depth
Method: monte carlo ray bundles from ZHS distribution, then ray-trace through the ice+firn to surface, then use fresnel equations
Does NOT yet do s & p polarizations properly, just uses average  scalar E
5/12/2019
P. Gorham

4. Stage 2: detector, pulse simulation
Best done in Fourier domain  easy to add random phasors to properly simulate thermal noise
Need to be careful with causality (filter delays)
5/12/2019
P. Gorham

5. Results: Volume, solid angle, depth, range
En = 3e18 eV (red): integrated Veff = 260 km3 sr
1/5 of old estimate: acceptance angle mistake due to snelling effects
En = 3e19 eV (blue): integrated Veff = 3800 km3 sr
~1/2 of old estimate, firn + taus + downgoing offsets other mistake
Depth vs range for 3, 30 EeV shows saturation of depth, also MC limitations
5/12/2019
P. Gorham

6. Ice depth distribution along track
mean depth = 1600m averaged over entire track
of order 1 attenuation length (depending on T distribution)
East Antarctica up to 4.4 km!
5/12/2019
P. Gorham

7. Existing Neutrino Limits and Potential Future Sensitivity
RICE, AGASA, Fly’s Eye limits for ne only
GLUE limits nm & ne
~80 hours livetime
FORTE limits nm & ne
3.8 days live, Greenland ice
SALSA & ANITA sensitivity:
Based on 2 independent Monte Carlo simulations: D. Saltzberg (SPIE02), Gorham (GLUE adaptation); nm & ne included, full-mixing not yet
Models:
Topological Defects: Sigl; Protheroe et al.; Yoshida et al.
AGN: Protheroe et al.; Mannheim
GZK neutrinos: Engel et al. ‘01
5/12/2019
P. Gorham

8. Summary We need more monte carlo work!
A very tricky business—approach with humility…
Effects to be included, areas for improvement:
Actual flight tracks and depth distribution
Temperature profiles
Need better tau/e/mu event generation
Polarization in both stage 1 and 2
Better simulation of detector & trigger bandpass responses
5/12/2019
P. Gorham