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HK: Physik der Hadronen und Kerne

HK 15: Poster-Sitzung: Kern- und Teilchen-Astrophysik

HK 15.7: Poster

Dienstag, 18. März 2003, 13:30–15:30, Foyer

The ⁶⁹Ge calibration of the GNO counters — •Dario Motta¹, Carla Cattadori², Nicola Ferrari², Wolfgang Hampel¹, Francis Xavier Hartmann¹, Florian Kaether¹, and Ute Schwan¹ — ¹Max Planck Institut für Kernphysik, Postfach 103980, 69029 Heidelberg — ²Laboratori Nazionali del Gran Sasso, S.S. 17/bis km 18+910, I-67010 Assergi (L’Aquila), Italia

With the results of the SNO experiment the solar neutrino physics has left the discovery phase and entered a new one, where high precision measurements are needed to constraint the ν -oscillation scenarios. The gallium radiochemical experiments SAGE (Baksan, Russia) and GNO (Gallium Neutrino Observatory), the successor experiment of Gallex at the Gran Sasso underground laboratories, Italy, are still so far the only ones sensitive to the fundamental pp and ⁷Be solar neutrinos. One of the major goals of the GNO experiment is to measure the solar neutrino interaction rate with a precision of 5% (compared to 10% in Gallex). The statistical error will shrink along with the measurement time, it is therefore essential to reduce the systematic error. The letter was ≃ 6% in Gallex, dominated by the 4.5% uncertainty in counting efficiency. The GNO collaboration has therefore undertaken a campaign of calibrations using ⁶⁹Ge, with the goal to measure the counting efficiency of all the GNO-Gallex counters with a precision at the level of 1%. We describe the principle of this measurement and report on the first preliminary results.