1. The ARA concept and history 2010-2011 construction activities Future plans The ARA concept and history 2010-2011 construction activities Future plans Kara Hoffman University of Maryland on behalf of the ARA collaboration Kara Hoffman University of Maryland on behalf of the ARA collaboration

2. Some considerations: Frequency range and band width. Antenna type Geometry (depth and spacing): Spacing of antennas Shadowing effect  Deeper is better Ice Temperature  Shallower is better Drilling cost and time– Deep=expensive Hole diameter limits design of antennas Wet/dry hole (dry doesn’t have to be sealed although holes may close anyway) Index of refraction varies with depth for first 100-200 meters (known as “firn”) due to compactification of snow.

3. ARA 37 layout Goal is to count events, not reconstruct the angles as would be needed for observatory class instrument, so a clustered design was adopted. A single station can provide a stand alone trigger -> trigger locally. Spacing increased to 2 km from 1.33 km in original proposal due to recent indications of a possibly heavier nuclear spectrum.

4. ARA station detail

5. Volumetric acceptance Angular resolution

6. See ArXiv: 1105.2854 for flux references

8. RAM: Rapid Air Movement Drill Hot water drill 200m in ~1/2 day 6” hole Wet hole- must be pumped out or electronic made watertight Deepest holes drilled in 10/11: ~160 m Hot water drill 200m in ~1/2 day 6” hole Wet hole- must be pumped out or electronic made watertight Deepest holes drilled in 10/11: ~160 m Hot water drill

9. monitor 60-1000 MHz at sensitivity levels of -110dB Test drill Test ice properties Begin testing station prototypes Essentially a “shallow” ARA station Testbed goals

10. Quad slot- H-pol Only narrow holes (10-15 cm) are feasible: need narrow antennas power and comms must pass through antenna to avoid cable shadowing Hpol information provided by slotted antenna Birdcage-Vpol

12. Deep -can be seen at >km scale distances strong pulses ~5kV azimuthally symmetric bicone antenna - eliminates systematics from cable shadowing effects goals: radioglaciology and calibration Deep -can be seen at >km scale distances strong pulses ~5kV azimuthally symmetric bicone antenna - eliminates systematics from cable shadowing effects goals: radioglaciology and calibration last access to deep IceCube holes in 2010- 2011 3 high voltage calibration transmitters will be installed on IceCube strings- 2 at 1450 m and 1 at 2450 meters

14. A collaboration has been formed to build an englacial array large enough to detect cosmogenic neutrinos An array concept has been proposed, with fine tuning of instrumentation and spacing to be optimized during the development phase. Funding ($4M from U.S. NSF) and foreign agencies has been granted for the development phase (ince April 20, 2010) Work commenced in the Polar season of (2010-2011) with the TestBed installation The first “real” ARA station will be installed in the coming austral summer A proposal for the balance of the array was submitted in May. If neutrinos are detected, a ~1000 km 2 array may be proposed in the future. First analysis of testbed data will be shown by Amy Connolly A collaboration has been formed to build an englacial array large enough to detect cosmogenic neutrinos An array concept has been proposed, with fine tuning of instrumentation and spacing to be optimized during the development phase. Funding ($4M from U.S. NSF) and foreign agencies has been granted for the development phase (ince April 20, 2010) Work commenced in the Polar season of (2010-2011) with the TestBed installation The first “real” ARA station will be installed in the coming austral summer A proposal for the balance of the array was submitted in May. If neutrinos are detected, a ~1000 km 2 array may be proposed in the future. First analysis of testbed data will be shown by Amy Connolly