Upgrade of the POLDI diffractometer with a ZnS(Ag)/6LiF scintillation detector read out with WLS fibers coupled to SiPMs

J-B Mosset,W Wagner,M Hildebrandt,A Stoykov,V Davydov,H Van Swygenhoven

doi:10.1088/1742-6596/528/1/012041

Abstract

A thermal neutron detector based on ZnS(Ag)/6LiF scintillator, wavelength- shifting fibers (WLS) and silicon photomultipliers (SiPM) is under development at the Paul Scherrer Institute (PSI) for upgrading the POLDI instrument, a pulse-overlap diffractometer. The design of the detector is outlined, and the measurements performed on a single channel prototype are presented. An innovative signal processing system based on a photon counting approach is under development. Its principle of operation is described and its performances are evaluated on the basis of a Monte Carlo simulation.

Highlights

POLDI (Pulse-Overlap Diffractometer) [1] is a neutron time-of-flight diffractometer commissioned in 2002 at the Swiss neutron spallation source (SINQ) at Paul Scherrer Institute (PSI)
The instrument is designed to function as a strain scanner for the investigation of residual stress in engineering materials and components, and for in-situ deformation measurements
To allow a simultaneous measurement of the axial and transverse strain components during in-situ measurements, POLDI will be upgraded with two oppositely placed detector banks based on ZnS(Ag)/6LiF scintillator replacing the actual single 3He detector

Summary

Introduction

POLDI (Pulse-Overlap Diffractometer) [1] is a neutron time-of-flight diffractometer commissioned in 2002 at the Swiss neutron spallation source (SINQ) at PSI. The fiber pitch and the thickness of the scintillating layers are geometrical parameters which need to be optimized in terms of light yield and neutron absorption to maximize the neutron detection efficiency.

Results

Conclusion