The AMANDA-II detector will continue to take data during the construction phase of IceCube. During and after this period, members of the AMANDA-II (and IceCube) collaborations will be writing theses and publications based on analyses of AMANDA-II data. Since some members of the AMANDA-II collaboration are not members of IceCube, AMANDA-II will continue to produce an independent data stream. Also, since AMANDA-II needs to digitize its PMT signals within a few microseconds, it must be running and triggering independent of IceCube.
During the 2001/2002 and 2002/2003 seasons the AMANDA-II detector will be upgraded with waveform recording of its channels with optical readout. The DAQ system will in the same period be upgraded in order to increase data capacity and reduce dead time. No significant further upgrades of AMANDA-II are foreseen after the 2002/2003 season. Thereafter, the AMANDA-II detector will mainly need maintenance and calibration, and as such it will take data with minimal investment in personnel.
The AMANDA-II detector will be surrounded by IceCube strings (see fig. 59), permitting the two detectors to be run in coincidence. As the number of deployed IceCube strings increases, data taken from a combination of the two detectors will provide a useful testing ground for IceCube software, an important calibration tool for IceCube, and accelerate the ability of IceCube to produce scientific results.
Coincident triggering of AMANDA-II and IceCube is feasible at several levels. One could treat AMANDA-II and IceCube as completely independent entities at trigger level and write out the triggered data in two independent output streams. Selecting coincidence events can then be done offline, or in the IceCube event builder, using each detector's GPS timestamps. This scheme is simple, but it has the (perhaps unimportant) drawback that it will miss parts of those events which are below trigger threshold in one detector but not the other. It will also miss coincident events which are below threshold in both detectors.
It is possible to correlate events earlier in the data stream. The global trigger in the IceCube DAQ system receives hit information via ethernet and the global trigger software runs on a standard computer (see Sec. 7 for details). By sending similar information from AMANDA-II to the IceCube global trigger, a search for correlations between the two detector systems can easily be done, without the need for any new hardware. The timestamps for AMANDA-II hits would have to be corrected by the measured signal delays due to the down-hole optical fibers, but this can be accomplished with a straightforward look-up table in the global trigger software.
The information that both detectors have correlated hits can be sent to both systems and flagged in their respective data structures. This will make offline analysis easier. It is also possible to write out a data stream with fully combined data information from AMANDA-II and IceCube.
The information coming from AMANDA-II will differ in format and content from IceCube data (with the partial exception of the DOMs in AMANDA-II string 18). The channels in AMANDA-II which have only electrical read out will have no waveform information, only time, TOT and ADC information. The AMANDA-II channels with optical readout will have waveform information, but with different sampling frequency than that of IceCube. Data format translation and the ability of the IceCube offline analysis software to handle disparate information content are therefore required.
The tasks outlined above require some IceCube software effort, but that effort should not be substantial in the context of a well-designed IceCube software system. Further effort to maintain and calibrate AMANDA-II is also needed, and will be part of the winter-over responsibilities, with oversight and calibration analysis work done by IceCube and AMANDA-II physicists. Overall, the effort to integrate AMANDA-II and IceCube is not large, and the returns on the effort will substantially outweigh the investment.
