University of Wisconsin-Madison

First Year Performance Paper - Section 6.2

6.2 String-21 and SPASE

SPASE and String-21: Distribution of zenith (a) and azimuth (b) of showers reconstructed by SPASE. The black histograms show events with a muon trigger in String-21, while the unshaded histograms show all showers reconstructed by SPASE. Azimuth is defined here in the SPASE coordinate system.
SPASE and String-21: Distribution of zenith (a) and azimuth (b) of showers reconstructed by SPASE. The black histograms show events with a muon trigger in String-21, while the unshaded histograms show all showers reconstructed by SPASE. Azimuth is defined here in the SPASE coordinate system.

The SPASE scintillator array has a detector spacing of 30 meters and hence a threshold for air-showers about an order of magnitude lower than IceTop. It can therefore extend the IceCube primary composition analysis to lower energy. The SPASE data acquisition system was upgraded at the end of 2002, and analysis of coincidences with AMANDA-II is currently underway to extend the investigation carried out with AMANDA-B10 before 2002 [35]. Fig. 31 shows the showers that are seen by both SPASE and String-21.