Showing papers by "Charles L. Melcher published in 2001"
Patent•
28 Feb 2001TL;DR: In this paper, a Cerium dopant (CeO2) is added to a mixture of Lutetium Oxide (Lu2O3) and Silicon Dioxide (SiO2), and the mixture is heated until melted to define a melt.
Abstract: A Cerium-Doped Lutetium Oxyorthosilicate scintillator boule having a graded decay time. The method for manufacturing an LSO:Ce crystal boule having a decay time gradient decreasing from the top end to the bottom end first includes the step selecting an iridium crucible. The crucible is selected based upon its diameter relative to the diameter defined by said crystal boule. The crucible is also selected based upon its volume relative to the volume of the crystal boule to be grown. A Cerium dopant (CeO2) is added to a mixture of Lutetium Oxide (Lu2O3) and Silicon Dioxide (SiO2). The composition is heated until melted to define a melt. A seed crystal is then placed in contact with the melt, is rotated, and slowly withdrawn, thereby yielding an LSO:Ce crystal boule defining a decay time gradient.
18 citations
Patent•
06 Apr 2001
TL;DR: In this article, a method of improving the light yield of Oxyorthosilicate scintillation crystals, such as Lutetium, Yttrium, and LUTetium Gadolinium, was proposed, where the temperature is ramped up from room temperature to the annealing temperature over a selected period of time.
Abstract: A method of improving the light yield of Oxyorthosilicate scintillation crystals, such as Lutetium Oxyorthosilicate, Yttrium Oxyorthosilicate, Lutetium Gadolinium Oxyorthosilicate or Lutetium Yttrium Oxyorthosilicate scintillation crystals. In accordance with the teachings of the preferred embodiment, the Oxyorthosilicate scintillation crystals are annealed in a atmosphere selected to be a reducing atmosphere or slightly oxidizing at a selected annealing temperature. In this regard, in the preferred embodiment, the Oxyorthosilicate scintillation crystals are heated in a furnace. During the annealing cycle, the temperature is ramped up from room temperature to the annealing temperature over a selected period of time. After a second selected period of time of sustaining the annealing temperature, the annealing temperature is then ramped down over for a selected period of time. Annealing Oxyorthosilicate scintillation crystals in this manner is shown to improve the scintillation efficiency of the Oxyorthosilicate scintillation crystal.
8 citations