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Super-Kamiokande, Institute for Cosmic Ray Research, University of Tokyo

Super-Kamiokande, Institute for Cosmic Ray Research, University of Tokyo
In addition to the regular observations of atmospheric neutrinos and solar neutrinos, the Super-Kamiokande(note 1), at the University of Tokyo, needs to reliably capture neutrino events from supernova explosions. These only occur once every few decades and can only be observed for 10 to 20 seconds. As a result, measurements must continue non-stop 24 hours a day, 365 days a year.

To accumulate, analyze and manage the massive amount of data (approx. 150 GB per day) collected from the over 11,000 photomultiplier tubes; 270 blade servers and a high performance file system have been installed.

This Fujitsu provided system meets the requirements by simultaneously delivering the high reliability required for constant observation, with the high performance required for analyzing large volumes of data.
High reliability, high performance system for reliably capturing neutrinos

Subterranean system

The real-time subterranean system demands high operational efficiency. It is connected to the experiment observation system through a dedicated interface, and performs data collection and format conversion. Importantlym the system is constructed so that experimental observation data is not lost, even if communication with the outside system data servers is lost. This provides a no loss collection capability for data from events that cannot be observed a second time.

The system consists of Fujitsu PRIMERGY servers and ETERNUS storage systems.

Outside system

The outside system accumulates and analyzes observation data sent from the subterranean system (approx. 700 GB per day). This is stored on the data servers once the software, running on the data analysis units, removes events that are clearly unneeded (approx. 150 GB per day).

Detailed event reconstruction software is used on the accumulated data, on the data servers, to select and reconstruct neutrino events. Physical analysis is used on the events selected, to gain more in-depth understanding of the properties of neutrinos. This requires high CPU processing capacity and high speed data access.

The system is capable of executing a maximum of 1080 jobs simultaneously, to provide high-speed parametric analysis processing. To assist this, throughput capacity of 960 MB per second (average value for reads and writes) is achieved through the disk unit and file system design.

This system consists of PRIMEQUEST mission critical IA servers, PRIMERGY servers, and ETERNUS storage systems.

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Footnote

1: Super-Kamiokande

This is the world's largest water Cherenkov cosmic elementary particle detector. This not only measures neutrinos from supernova explosions, but also observes atmospheric neutrinos, solar neutrinos, and man-made neutrinos emitted from Tokai village in Ibaraki prefecture (T2K experiment).