Upgrading the Kiel Neutron Monitor

The Neutron Monitor in Kiel is one of the longest operating Neutron Monitors in the world, it has been operating continuously since the IGY 1957. The original counting electronics was upgraded in the mid-90's in collaboration with the IZMIRAN group, using a redundant arrangement of standard PCs. Since this upgrade, one-minute measurements of Cosmic Rays have been available in near real-time. Even though this setup has been operating without any problems for the last ten years, the hardware needs replacement to prevent data loss in case of failure of the aging hardware. For this we are preparing a new set of data acquisition electronics that will be set up in parallel to the existing electronics. A programmable automation controller (PAC) is the centrepiece of the upgraded electronics. A PAC combines the advantages of programmable logic controllers (PLC), the packaging, the industrial specifications, and the reliability, with the functionality and flexibility of a PC. The PAC runs a real-time OS and can be programmed with LabVIEW. The recorded data are transfered in real-time to a web server via ethernet, and, for redundancy, stored in the device on CompactFlash media. We present data from the Kiel Neutron Monitor for the October/November 2003 events, as well as others, which demonstrate the high resolution and sensitivity of the currently existing system. By using optimal-filtering techniques (Kalman filter), we determine onset and decay times of these ground level events (GLE), and compare them with data from other neutron monitors. We investigate the desirability of higher time resolution and its impact on the reliability of the determination of onset times.