NEUTRON MONITOR DATA FOR JUNGFRAUJOCH AND BERN DURING THE GROUND-LEVEL SOLAR COSMIC-RAY EVENT ON 28 October 2003 R. Buetikofer and E.O. Flueckiger Physikalisches Institut, Universitaet Bern Sidlerstrasse 5, CH-3012 Bern, Switzerland This report includes information on the processing and use of the data for the ground-level solar cosmic ray event on 28 October 2003 obtained by the following three neutron monitors operated by the Cosmic Ray Group of the University of Bern: i) The standard IGY neutron monitor with 18 BF3- counters at Jungfraujoch (geographic latitude: 46.55 N; geographic longitude 7.98 E; effective vertical cutoff rigidity, Epoch 2000.0: 4.49 GV; altitude 3570 m). This detector is an integral part of the worldwide network of neutron monitors, and data of this monitor have been published regularly since 1958 (Debrunner et al., 1987). ii) The IQSY-NM64 neutron monitor with 3 counter tubes at Jungfraujoch (altitude: 3475 m). This monitor has been in operation since 1986 (Debrunner et al., 1987; Schubnell, 1988). iii) The special neutron monitor (Buetikofer, 1988) with 58 IGY-type counter tubes in Bern (geographic latitude: 46.95 N; geographic longitude: 7.456 E; altitude: 570 m). The last complete hour (in UT) before the onset of the particle increase at Earth was used as the baseline time interval, i.e. 28 October 2003, 1000 - 1100 UT. For the Jungfraujoch neutron monitors the following data are given: Hourly data 27 October 2003 0000 - 2400 UT 28 October 2003 0000 - 0900 UT 1-minute data 28 October 2003 0900 - 2400 UT 29 October 2003 0000 - 1200 UT Hourly data 29 October 2003 1200 - 2400 UT For the Bern neutron monitor, the same data are given with the difference that the small-time data include 5- minute values only. All data are presented in the "Standard Format for Cosmic Ray Ground-Level Event Data" as suggested by Shea et al. (1987), and additions according to the document "STANDARD FORMAT FOR COSMIC RAY GROUND-LEVEL ENHANCEMENT DATA" at the GLE data base. The following names were used to identify the different monitors: JUNGFRAUJ for the 18-IGY and JUNGFRAU2 for the 3-NM64 neutron monitors at Jungfraujoch, BERN for the special neutron monitor in Bern. All counting rates of the neutron monitors were normalized with the same correction factors as used for the publications on our wepsite http://cosray.unibe.ch and for data sent to the world data centers. The factors for the time interval during the event are given in the following table for the different sections of the neutron monitors. neutron monitor section section section 1 2 3 IGY neutron monitor 0.885 0.908 0.792 Jungfraujoch NM64 neutron monitor 0.975 0.976 1.010 Jungfraujoch special neutron monitor 1.067 1.000 1.060 / Bern 1.000 Pressure corrected hourly averages were obtained from pressure corrected 1-minute values. The hourly pressure values were obtained by averaging the 1-minute pressure readings. Section 3 of the IGY neutron monitor at Jungfraujoch is the central section. Section 1 is west of section 3 (towards the building) and section 2 is east of section 3. In the NM64 neutron monitor Jungfraujoch section 1 is located toward the mountain, section 2 is the central section and section 3 is located toward the glacier. For the special neutron monitor in Bern section 1 is AL+AR+BL+BR and section 2 is CL+CR. In contrast to the data books where the count rates of the sections FL and FR are not taken into account, the data in this report include all sections of the special neutron monitor. Section 3 therefore is DL+DR+EL+ER+FL+FR. The correction factor for (DL+DR+EL+ER) is 1.060, whereas for (FL+FR) it is 1.000. (For details see Buetikofer, 1988) In the special neutron monitor in Bern the counter tubes are placed at different positions relative to the absorbers. Therefore different barometric pressure coefficients were used for the pressure correction of the count rates of the different sections. The barometric pressure coefficients according to Buetikofer (1988) were used. These coefficients are given in the table below. section barometric coefficient in % / mmHg AL, AR -0.975 BL, BR -0.961 CL, CR -0.962 DL, DR -0.920 EL, ER -0.948 FL, FR -0.928 The barometric pressure coefficient of -0.9557 % / mmHg given in line 3 of the header of the standard GLE format for the special neutron monitor in Bern corresponds to an average barometric pressure coefficient for the total count rate. The Swiss neutron monitor data may be used under the following conditons: (1) You agree to achnowledge the source of the data in any published use. Example: "Jungfraujoch neutron monitor data were kindly provided by the Cosmic Ray Group, Physikalisches Institut, University of Bern, University of Bern, Switzerland" (2) You agree to send a copy of any paper using these data to: Erwin Flueckiger Physikalisches Institut University of Bern Sidlerstrasse 5 CH-3012 Bern / Switzerlaand (3) You may share these data with colleagues, provided you inform them of these conditions. While the published data are accurate to the best of our knowledge, we reserve the right to correct errors without notifying users. Acknowledments: The operation of the neutron monitor is supported by the Swiss National Science Foundation, grant 20-0067092.01 and by the International Foundation High Altitude Research Stations Jungfraujoch and Gornergrat (HFSJG), CH-3012 Bern, Switzerland. References: Buetikofer, R., Zum Wiederaufbau des Multiplizitaetsneutronenmonitors in Bern, Lizentiatsarbeit, Physikalisches Institut, Universitaet Bern, 1988 Buetikofer, R., E.O. Flueckiger, Pressure Correction of GLE Measurements in Turbulent Winds, 26th ICRC, Salt Lake City, Conference Papers 6, 395, 1999 Debrunner, H., E. Flueckiger, and M. Schubnell, Present and Future Activities of the Bern Cosmic Ray Group in the Field of Solar Neutrons, Workshop on Solar Neutrons, 20th ICRC, Moscow; Special Report of the A.F. Ioffe Physico-Technical Institute of the Academy of Sciences of the USSR, Leningrad, 7, 1987. Schubnell, M., Zum Nachweis solarer Neutronen auf Jungfraujoch, Inauguraldissertation, Physikalisches Institut, Universitaet Bern, 1988 Shea, M.A., D.F. Smart, J.E. Humble, E.O. Flueckiger, L.C. Gentile, and M.R. Nichol, A Revised Standard Format for Cosmic Ray Ground-Level Event Data, 20th ICRC, Moscow, Conference Papers 3, 171, 1987.