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HK: Physik der Hadronen und Kerne

HK 9: Postersitzung: Instrumentation und Anwendungen

HK 9.26: Poster

Tuesday, March 20, 2001, 10:30–12:45, R

A high-efficiency silicon detector for ultracold neutrons — •Gerd Petzoldt¹, Igor Altarev¹, Albert Fleischmann², Stephan Gröger¹, Erwin Gutsmiedl², F. Joachim Hartmann¹, Peter Maier-Komor¹, Stephan Paul¹, Uwe Trinks¹, and Wolfgang Schott¹ — ¹Physik-Department, Technische Universität München — ²FRM II, Technische Universität München

A high-efficiency silicon PIN-diode detector using the ⁶Li(n,α)t reaction to detect ultracold neutons (UCN) has been developed. Originally designed to work at low temperature inside the storage volume of a superthermal UCN source, it can also be used at room temperature. The detector surface reflectivity for UCN is reduced to a few percent by means of a multilayer structure consisting of materials with positive and negative scattering potentials. The efficiency of detectors with a composition of ⁶²Ni and ⁶LiF was measured at the ILL PF2 UCN guide to be about 80 % in the 100 neV- 200 neV UCN energy range using a gravitational spectrometer. UCN detectors with Ti and ⁶LiF multilayers designed for high UCN detection efficiency even for UCN energy ≤ 50 neV have been manufactured and will be tested at ILL.