Ce: BaF2 crystal (also known as cerium-doped barium fluoride crystal) is a crystal with the fastest decay time and is widely used in scientific research and industrial high-energy ray detection. The fast components of pure BaF2 crystals are concentrated in the peaks of 195nm and 220nm, and the decay time is about 800ps. In addition, there is a slow component with the peak of the emission spectrum near 310nm, and the decay time is about 600ns. The introduction of cerium ions(Ce3+) can effectively suppress slow components and improve the performance of the crystal.

Ce: BaF2 crystal shows stable physical and chemical properties, with a density of 4.83g/cm3, strong blocking ability, and a radiation length of about 2.05cm. These advantages are traditionally made it better than scintillation crystal of NaI. At the same time, the refractive index of BaF2 is close to that of optical glass, which makes it easier to export light in coupling with the photomultiplier tube. Ce: LuAG crystals are widely used in the detection of high-energy particles, such as β-rays and γ-rays. The large-sized Ce:BaF2 crystal has been used as a traditional scintillator for gamma-ray detection and frontal X-ray imaging. However, Ce: BaF2 crystal also has two shortcomings. The first is that its light yield is much lower than that of NaI; the second is that the emission wavelength of BaF2 crystal is in the ultraviolet region, and it needs to be equipped with more expensive ultraviolet photomultipliers in use.


Parameter

Material Features

Chemical formulaCe:BaF2
Density (g/cm3)4.893
Melting point (℃)1386
Hardness (Mho)3
Hygroscopicslightly
Cleavage<111>
Lattice Constant (nm)0.6196
Solubility(g/100gH2O)0.17
Thermal expansion coeff (C-1)18.4*10-6
Thermal conductivity coeff (W/mk)11.72

Scintillator Properties

Wavelength (Max. Emission) (nm)310
Wavelength range(nm)170-460
Decay time(ns)630(slow);0.87/0.88(fast)
Light yield(photons/keV)10(slow);1.9(fast)
Refractive index1.49@310nm
Radiation length(cm)2.026
Optical transmission(um)0.15-12.5
Transmittance(%)>90(0.35-9um)
Reflection loss/surface(%)6.8
Lattice constant(nm)0.6196
Afterglow (after 3ms) (%)0.005
Light output relative to Nal(Tl) (%)20(slow),4(fast)

Feature

  • Very fast decay time
  • High density
  • Refractive index matching
  • Stable physical and chemical properties

Application

  • γ-ray detection
  • Charged particle detection Ø
  • Ionizing radiation detector
  • X-ray imaging
  • Radiation scintillation screen

Reference

[1]  Drozdowski W ,  Wojtowicz A J . Fast 20 ns 5d–4f Luminescence and Radiation Trapping in BaF2:Ce[J]. Nuclear Inst & Methods in Physics Research A, 2002, 486(1):412-416.
[2] Fan, Yang, Junfeng, et al. La- and La-/Ce-Doped BaF2 Crystals for Future HEP Experiments at the Energy and Intensity Frontiers Part II[J]. IEEE Transactions on Nuclear Science, 2018.
[3]  Li S W ,  Jiang Y ,  Ju S G . Preparation of the BaF2: Ce3+, Yb3+ Nanoparticles and near Infrared Luminescent Properties[J]. Applied Mechanics & Materials, 2015, 707:98-101.

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