Detectors for X-Ray Imaging
Development of High Spatial Resolution Detectors for X-Ray Imaging Based on YAG:Ce and YAP:Ce Scintillation Crystals
Tech Area / Field
- INS-DET/Detection Devices/Instrumentation
- INF-IMA/High-Definition Imaging and Displays/Information and Communications
8 Project completed
Senior Project Manager
Tyurin I A
A.I. Alikhanyan National Science Laboratory, Armenia, Yerevan
- Institute for Physical Research, Armenia, Ashtarak-2
- Argonne National Laboratory (ANL) / Advanced Photon Source, USA, IL, Argonne\nCornell University / Laboratory of Atomic and Solid State Physics, USA, NY, Ithaca\nEuropean Synchrotron Radiation Facility, France, Grenoble\nDESY, Germany, Hamburg\nCERN, Switzerland, Geneva
Project summarySuccessful creation and operation of synchrotron radiation (SR) accelerator facilities of third generation (ESRF, APS, NSLS, Spring8, BESSY-2, CANDLE-Armenian new project) stimulated the development of new directions in applied research and necessitated the development of UV, VUV and X-ray range new devices. High sensitive and high resolution detecting of X-ray images has always been and still remains an actual problem. At present time, position- sensitive detectors based on different physical principles are developed and used [1-11] in leading centers of SR usage. A special emphasis is placed on the obtaining of high resolution and magnification of detectors sensitive area. The appearance of CCD matrixes with large field opens up new possibilities for their application in experiments with synchrotron radiation usage. X-ray radiation detectors based on the CCD, as a rule; include a scintillator, an optic system of visible radiation and a CCD. Development and construction of two- dimentional highly sensitive X-ray detectors remain topical up to now. By their characteristics, YAG: Ce and YAP: Ce crystals are perspective scintillators for the creation of X-ray radiation detectors in a wide range from VUV to 200 KeV.
Quantum efficiency of YAG: Ce and YAP: Ce crystals luminescence exceeds considerably the quantum efficiency of BGO crystals.
The objective of the project are: study of scintillation characteristics (energy, spectral, temporal, angular) of YAG: Ce and YAP: Ce crystals; development and construction of position-sensitive detectors on the basis of YAG: Ce scintillation crystals mosaic, optic system and CCD matrix (version 1) with spatial resolution up to 1µm and on YAP: Ce (version 2) crystals mosaic, special optics system and CCD matrix (or image converter-intensifier with CCD for version 2) with spatial resolution of ~1µm; detectors testing on beamline. The created detectors can be used on beamlines for the study of materials in a wide range of X-rays, for example in computed microtomography (medical beamline), as well as in other experiments on radiography and diffraction-refractive topography.
The scope of the project is also the reorientation of scientists, previously employed in defense programs, to civil work. The qualification of the project manager and executors allow to performing the work described following operations, because previously they were occupied with development and study of detectors characteristics, as well as with the application of detectors in various researches in X-ray range with SR usage. The project authors developed the technology and realized the performance of various Yb and Ce doped single crystals scintillators YAG, LuAG, YAP grown by Czochralski and Bridgman technique; developed, constructed and successfully applied image converter-intensifier in the range of VUV; proposed and demonstrated the look-out of position-sensitive detector usage for the sky review in far UV; developed detectors on the basis of CCD matrix for VUV and X-ray range. Various X-ray-optic for X-ray-optic visualization are developed and realized. The experience on synchrotron (x-ray) beams forming with required spatial and energy characteristics with the help of mirrors and crystal monochromators is acquired, researches on the perfection of crystals wide class with the use of topographic and diffractometer X-ray methods are performed. There is a project of research beamlines of "CANDLE" light source, where it is foreseen to use detectors, planned to develop within the framework of this project.
The major results of the project will be:
Scientific and Practical
- extension of the knowledge in the field of the influence of X-ray radiation on condensed agents (YAG:Ce and YAP:Ce monocrystals);
- development of control and readout software, construction of electronic package for the CCD matrix;
- development and creation of a position-sensitive detector on the basis of YAG:Ce crystals mosaic with CCD;
- development and creation of a position-sensitive detector on the basis of YAP:Ce crystals mosaic with CCD.
YAG:Ce and YAP:Ce position-sensitive detectors can be used in X-ray imaging:
- refraction-contrast imaging - imaging of low absorbing specimens;
- phase-contrast imaging - imaging of biological samples with an X-ray interferometer;
- X-ray microtomography- three-dimensional imaging, X-ray fluorescence microtomography;
- X-ray fluorescence microscopy- imaging of trace elemental distribution with a scanning X-ray microprobe;
- X-ray topography- static and dynamic processes of crystal growth, phase transition and plastic deformation in crystals. Crystal lattice imperfections;
- X-ray microscopy – imaging of materials by magnifying with microfocusing elements.
The following Institutions may be interested in the project results:
- centers on synchrotron radiation application;
- scientific laboratories, which use X-ray radiation in their research;
- medical centers, which use X-ray equipment;
- companies involved in production of single crystal scintillators and scientific equipment.
The following works are foreseen to be performed in the project:
- study of YAG:Ce and YAP:Ce single crystals, growing and parameters optimization;
- study of spectral, energy and temporal characteristics of YAG:Ce and YAP:Ce crystals luminescence;
- development and construction of the converter-intensifier in the 185-360nm ranges;
- development and construction of a two image detectors based on a CCD matrix 800x800 pixels, electronic assemblage and control software for CCD;
- development of the mounting technology and mounting of mosaic from YAG:Ce and YAP:Ce crystals;
- creation of X-ray detectors two prototype patterns based on:
- version 1 – mosaic from YAG:Ce crystals, optic systems and CCD matrix 800x800 pixels;
- version 2 – mosaic from YAP:Ce crystals, special optics system, converter-intensifier with CCD matrix;
- development and creation of the position-sensitive X-ray detectors based on:
- version 1- mosaic from YAG:Ce crystals, optic systems and CCD matrix 4000x7000 pixels;
- version 2 – mosaic from YAP:Ce crystals, special optics system and back illumination CCD matrix 4000x7000 pixels;
- laboratory studies of X-ray detectors physical characteristics;
- technical documentation and operating statement preparations.
The role of foreign collaborators consists in the performance of joint researches and workshops, information exchange and results discussion during the project realization, joint usage of equipment and materials, joint publications.
For the purpose of project realization the following technologies, approaches and engineering peculiarities will be used:
- crystals growth by Czochralski and Bridgmen technique;
- high-accuracy block optic treatment of crystals;
- mosaic assemblage under microscope;
- photometric method of crystals luminescence measurement;
- X-ray topographic and diffractometer control method of mosaic assemblage from crystals;
- X-ray fluorescence spectroscopy (XFS);
- X-ray absorption spectroscopy (XAS);
- cathode sputtering of thin coatings;
- optic control of the accuracy of detectors issues docking;
- cryogenic technique for CCD cooling.
In the issue of the project realization, whole series of objectives will be gained including those considered by ISTC as priority ones:
- reorientation of eminently qualified personnel to the solution of peaceful problems;
- support of fundamental and applied researches and technological development for civil purposes;
- further integration of scientists and engineers, working in the armament field, into an international community of scientists and opportunities for creative and business contacts with foreign specialists and companies;
- assistance to the solution of national and international problems. It will appear in the introduction of the developed detectors to production, to the application on CANDLE experimental beamlines and other fields of science.
The proposed project is compiled in accordance with ISTC instruction; it is necessitated by the alternative for scientists and engineering personnel, previously employed in the field of armament and defense technologies.
The International Science and Technology Center (ISTC) is an intergovernmental organization connecting scientists from Kazakhstan, Armenia, Tajikistan, Kyrgyzstan, and Georgia with their peers and research organizations in the EU, Japan, Republic of Korea, Norway and the United States.
ISTC facilitates international science projects and assists the global scientific and business community to source and engage with CIS and Georgian institutes that develop or possess an excellence of scientific know-how.