A deep High-Powered Centered Radio Beacon for ARA Bob Morse—IceCube Univ of Wisconsin
Installing an antenna system at a depth of 1000 meters in South Pole Ice • Center near the middle of the ARA array • Antennas connected with surface station using low-loss coaxial cable • Simultaneously illuminate the entire ARA detector with tone-bursts, Askaryan pulses • Will allow instrument calibration, and study of ice attenuation and dispersion using the many constraint equations that will emerge
Beacon’s Surface Support -- Flexibility • Surface equipment can be repaired--when broken, modified—when inadequately designed, and allows science-driven evolution over the 10-15 year lifetime of this program. • It is not unreasonably to expect changing equipment needs and equipment failures to be part of the 10-15 year program.
Array Illumination—Pulse power levels • Ray-trace studies suggest 10^18 eV (EeV) GZK neutrino event in the center of ARA at a depth of 1000 meters should illuminate the entire detector. • Assumes ARA detectors at a depth of 200 meters. • ZHS analysis suggests an EeV Askaryan event could be simulated with a nanosecond bi-polar pulse of about 100 watts output from the antenna. • We later present simulated tone-bursts and Askaryan pulses being delivered to the antenna through 1000 meters of low-loss coaxial cable.
An IceCube borehole?—The best solution! • The 60 cm diameter would allow for more sophisticated antennas to be installed. • Easier to accommodate both V-pol and H-pol antenna, such at turnstyle/batwings(H-pol) and discone antennas. • If we miss the IceCube opportunity then we will have to consider drilling a much smaller dry-hole (10-15 cm) either using the shot-drill, or coring drill. Coring would be very slow and expensive.
Cable challenges • Cable has to withstand large ice freeze-back pressures. • Foam dielectrics in low-loss high-frequency cables are structural weak. • Currently working with Ericsson Cable Co. of Sweden—they made the Icecube cables—to develop a low-loss structurally strong coaxial cable
Amplitude attenuation and phase shifts • Attenuation • Phase advance
Nanosecond bi-polar “Askaryan” pulse at the end of 1000 meter Beacon cable