Commissioning of the new online system for the Super-Kamiokande experiment

The online system of the underground neutrino detector, Super-Kamiokande is scheduled to be upgraded in September of 2008 together with the front-end electronics and the data-acquisition will be started in October. The detector contains 50000 tons of pure water equipped with about 13000 photo-multipliers (PMTs) to detect Cherenkov light. In the new data acquisition scheme, we will not use the hardware event-trigger for the data reduction which is used in the current system but read out every hit data from the front-end electronics and process them by the online farm. By introducing this scheme, we aim at lowering the threshold of the detection energy for solar neutrino and analyzing consecutive events whose time interval is too long to detect in the current system. The new online system needs to process the dataflow of up to 800MB/s from the front-end electronics. We will utilize Gigabit and 10Gigabit Ethernet techniques and distribute the load over Linux PCs. In addition to the fast processing, the high availability is another important issue of the online system not to miss a supernova neutrino burst. We will report the final design, the performance of the system in the integrated test and the result in the commissioning run.