Fast, Dense Lu-Y mixed Oxide Ceramic Scintillators

Abstract

Dense inorganic scintillators that can be scaled up to large sizes are required for future colliders. These scintillators are expected to have a fast scintillation decay profile to mitigate pileup at high event rates and show radiation hardness up to tens of Mrad to withstand the high fluxes. There are only few scintillation mechanisms that provide ultrafast scintillation – one of them being the charge transfer transitions (CTT), in which the emission comes from an ion (e.g., Yb) changing its charge state.The Lu₂O₃ doped with Yb has been identified as a very promising scintillator due to its fast charge transfer transitions. Lu₂O₃ is also one of the densest hosts at 9.4 g/cm³, which makes it very attractive for HEP applications. Since, the melting point of Lu₂O₃ is very high (> 2,000°C) and its structure is cubic, the optically transparent material is manufactured using ceramic process.Samples of Lu₂O₃ and (Lu,Y)₂ O₃ doped with Yb were manufactured at RMD and evaluated at both RMD and Caltech. The samples of Lu₂O₃ doped with Yb show light yield as high as 500 ph/MeV and X-ray excited luminescence peaks around 370 nm. The Y mixed samples show light yield as high as 1,500 ph/MeV and their emission peaks around 420 nm. The scintillation decay time measured with a fast photomultiplier tube is around 1.2 ns for Lu₂O₃ samples, while the mixed samples show additional slower component (< 20 ns). The intensity of the slower component depends on the Yb concentration. With their high density and ultrafast decay, Lu and Y mixed oxide ceramics are promising for future HEP calorimetry, time of fight (TOF) applications, and high energy resolved radiography. Optical and scintillation properties and radiation hardness studies for both small and large size samples will be presented.

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