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HK: Fachverband Physik der Hadronen und Kerne
HK 17: Instrumentation IV
HK 17.4: Talk
Tuesday, March 12, 2024, 16:45–17:00, HBR 19: C 2
A neutron leakage detector for the free neutron lifetime experiment τSPECT — •Julian Auler1, Martin Fertl1, and Dieter Ries2 for the tauSPECT collaboration — 1Institute of Physics, Johannes Gutenberg University Mainz, Mainz, Germany — 2Paul Scherrer Institute, Villigen PSI, Switzerland
The neutron storage experiment τSPECT aims to measure the free neutron lifetime by confining ultracold neutrons (UCNs) in a three-dimensional magnetic trap. In contrast to material bottles, magnetic storage eliminates interactions with the trap wall, allowing for the neglect of systematic effects on the measured lifetime related to wall interactions, such as capture or inelastic scattering of UCNs. The presented neutron leakage detector is intended to investigate systematic effects related to the magnetic storage by detecting UCNs possibly escaping from the magnetic trap. Potential escape channels are, e.g., depolarization of UCNs in the radial confinement field produced by a cylindrical Halbach octupole array of permanent magnets or microphonic heating of UCNs due to vibrations of the trap. Because of the fast spatial drop-off of the radial octupole field, the detector covering the inner surface of the octupole must be very thin in order not to cut into the storage depth of the trap. For this purpose, a multilayer structure with a conversion and scintillator layer is used. Wavelength-shifting fibers are guiding the scintillation light from inside the experiment to the actual photosensor. In this talk, the design of the detector and first characterization measurements of suitable fibers will be presented and an outlook on future implementations will be given.