> 'Energy (TOF) and Position Sensitive Detection
of Ultra Cold Neutrons with Micrometric Resolution Using the TimePix Pixel Detector'
Energy (TOF) and Position Sensitive Detection
of Ultra Cold Neutrons with Micrometric Resolution Using the TimePix Pixel Detector
IEEE NSS/MIC Conf. Proc. (2008) N42-1
Ultra-cold neutrons (UCN) are neutrons with very small kinetic energies (below 300 neV). The energy is so low that they are reflected from the surface of many materials under any angle of incidence. These neutrons can be thus trapped by an effective Fermi potential and stored inside material “bottles”. Recently bound quantum states of neutrons in the earth’s gravitational field have been observed with UCN. A detector with spatial resolution of around 1 μm is required to be able to resolve such individual states. Being uncharged and having very low energy, ultra-cold neutrons cannot be detected in the silicon pixel detector directly but can be converted into charged particles in a thin layer deposited onto the sensor surface. The design of a position sensitive detector of UCN is based on coating the TimePix detector (300 um thick pixelated silicon sensor, 256 x 256 square pixels with pitch of 55 um) with suitable material converting UCN to highly ionizing particles. Two converter materials with high cross section for UCN absorption were studied by Monte-Carlo simulations and tested experimentally: 6Li (in form of 6LiF) and 10B. The performance of the TimePix device for detection of highly ionizing particles with very high spatial resolution (320 nm for 10 MeV alpha particles) has been already presented. The technique utilizes the charge sharing effect and it is based on proper analysis of individual recorded tracks (clusters). Results of these tests showed that it is possible to detect UCN with high spatial resolution (5 um) and high detection efficiency (70%). Moreover, thanks to the time measurement capability in each pixel of the device, the final detector can be effectively used also for Time-Of-Flight (TOF) experiments. This way a position and energy sensitive detector of UCN is constructed. Results of direct and TOF experiments with UCN and the TimePix device will be presented.
Cite article as:
J. Jakůbek, T. Jenke, P. Geltenbort, M. Platkevič, C. Plonka-Spehr, P. Schmidt-Wellenburg, J. Šolc, T. Soldner, "Energy (TOF) and Position Sensitive Detection
of Ultra Cold Neutrons with Micrometric Resolution Using the TimePix Pixel Detector", IEEE NSS/MIC Conf. Proc. (2008) N42-1 (2008)