Project
Fast timing high resolution nRPC-4D detector concept for neutron science
Code EXPL/FIS-NUC/0538/2021
Beneficiary Entity
LIP - Laboratório de Instrumentação e Física Experimental de Partículas
Project summary
In this project we propose to develop an innovative detector concept, nRPC-4D, which offers four-dimensional read-out capability (XYZ and time) and is intended for time-of-flight(TOF) neutron diffraction/reflectometry and energy- and time-resolved neutron imaging. These techniques are powerful tools to probe the structure and dynamic properties ofcondensed matter playing a crucial role both in fundamental and applied research in areas such as physics, chemistry, biology, medicine and engineering [1,2]. The importance ofneutron science for society is recognized by the EU which has invested 2 billion euros in the ongoing construction of the next generation neutron facility, the European SpallationSource (ESS), which is one of the world’s largest scientific and technological infrastructures being built today. The present state-of-the-art detectors cannot fully satisfy the tightrequirements of the next generation instruments planned for the ESS [3] and the future spallation sources [4] as well as of the upgrade programs of the existing facilities [5]. Forexample, new instruments for small-angle neutron scattering (SANS), reflectometry and macromolecular crystallography require detectors capable of providing simultaneously highdetection efficiency (>50%), low gamma sensitivity (<1E-6), time resolution down to 0.1 µs, sub-millimeter spatial resolution and counting rate up to MHz/cm2 [3,6,7]. Ultra-highspatial resolution (~0.2 mm) is especially important for investigation of the structure of protein crystals of sub-millimeter size by neutron macromolecular crystallography [6]. Thecapability to characterize samples of such small size is required since the growth of larger size crystals of biological macromolecules is very challenging. The same detector shouldalso provide TOF capability with sub-microsecond time resolution, required to conduct high-precision wavelength-resolved measurements at the spallation neutron sources [3].Another example where the current neutron detection technologies are not adequate is in MIEZE neutron spin-echo spectroscopy [8], which is a novel method with ultra-high energyresolution for studies of ferromagnets, superconducting vortex lattices, and magnetic skyrmion systems [9]. MIEZE requires neutron detectors with response time below 1 µs, verywell-defined detection planes and high spatial resolution. The goal of this project is to develop a detector concept which can offer high time and spatial resolutions, good detectionefficiency, high counting rate and low sensitivity to gamma rays. The nRPC-4D concept combines two technologies: t-RPC (timing resistive plate chamber) [10] invented in LIP forhigh energy physics applications [11] and, to give RPCs the capability to detect thermal neutrons, B4C neutron converters developed jointly by the University of Linkoping and ESS[12]. An intrinsic timing resolution on the order of nanoseconds for the measurement of neutron time-of-flight is expected thanks to the high time resolution of the t-RPCs (below100 ps for minimum ionizing particles, MIPs) and the short neutron flight time inside a thin converter layer. A spatial resolution below 0.1 mm has already been demonstrated byt-RPCs for MIPs [E], and it has also been shown by us that RPCs lined with a thin converter layer can provide high spatial resolution [13] combined with good detection efficiency[C]. During our work on this project we will perform detailed Monte Carlo simulations to optimize the detector design, develop new techniques for neutron event reconstruction andbuild a small-scale proof-of-concept detector prototype. The detector will consist of a stack of neutron-sensitive t-RPCs oriented normally to the direction of the incident neutrons. Itwill have the capability to determine all three spatial coordinates and the time of the neutron capture. New 4D event reconstruction techniques will be developed and validated insimulations. The detector demonstrator will be characterized at the FRM II neutron facility (the agreement to provide beam time was already granted). As the result of the project, anovel type of detector for thermal neutrons with 4D readout will be introduced, allowing a significant improvement of the time resolution compared to that of the existing detectors.Given the outstanding sharp timing capability and high spatial resolution, nRPC-4D detectors have a potential to enable new neutron methods based on time- and energy-resolvedneutron imaging.
Support under
Reforçar a investigação, o desenvolvimento tecnológico e a inovação
Region of Intervention
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