Colorimetric Energy-Sensitive Scintillators Based on Multilayer Thin Film Designs

Significance 

Presently, kinetic energy and fluence of radiation beams is monitored using radio-chromic films, ionization cells or phosphor screens coupled to photodiodes. With the widespread application of radiation beams, monitoring has become a prerequisite for efficient application. Currently, beam fluence measurements utilizes well established procedures, however, for the purposed of evaluation of the kinetic energy of the beam particles, intricate and more specific techniques have to be called upon for each particle type and energy range. For the latter, ionization cells have been utilized in the modern linear accelerators used for radiotherapy treatment. Alternatively, phosphor screens consisting of homogeneously distributed luminescent components with tuned selectivity and sensitivity to a particular type of radiation can be used to identify the position and shape of a particular beam of charge particles impinging onto a surface. Unfortunately, these systems are unable to provide adequate beam-energy information since their color emission response has only a negligible dependence on beam energy.

Recently, Spanish National Research Council (CSIC) researchers, Jorge Gil-Rostra, Francisco J. Ferrer, Juan Pedro Espinós, Agustín R. González-Elipe and Francisco Yubero developed a novel scintillator concept for the determination of the kinetic energy of electron and ion beams, that would help overcome the aforementioned drawback in the detectors. They proved the validity of the novel luminescent multilayer concept. In addition, they purposed to show that their novel concept complied with the strict composition, doping level, thickness and morphology characteristics as well as the well-known quantitative luminescent behavior when excited with radiation beams of charged particles within the kinetic energy range of interest. Their work is currently published in the journal, ACS Applied Material and Interfaces.

In brief, the research method employed entailed building of a multilayer system through the stacking of different phosphor and slowing-down layers at given depths and the correlation of the spectral distribution of the emitted light with the kinetic energy and nature of the radiation beam. As an overview, this procedure commenced with the qualitative description of the luminescent photonic multilayer concept. Two examples depicting the application of the general concept were then presented. Lastly, a brief analysis of the accuracy of the proposed colorimetric quantification was undertaken.

The authors observed that the developed devices could be designed “a la carte” according to the energy range and type of particles to be detected. Additionally, they noted that the emitted signals from the multilayer detectors were easily collected onto suitable spectrometers, thereby making the quantitative analysis of the spectral signal, using fingerprint spectra of the single luminescent layer stacked in the device as reference, quite easy.

In summary, the CSIC scientists successfully demonstrated the development of a novel photonic multilayer scintillator approach. Generally, this approach has been proven to be powerful and yet simple system for energy monitoring of charged-particle beams, either ions or electrons. Altogether, their technology has potential to be expanded to three dimensions, macroscopic beam monitors consisting of layered luminescent structures, where color and light intensity from each voxel would provide information on the kinetic energy and fluence of the particles reaching that point.

Colorimetric Energy-Sensitive Scintillators Based on Multilayer Thin Film Designs - Advances in Engineering

About the author

Dr. Jorge Gil-Rostra received his degree in Chemistry from de University of Burgos, Spain in 1998. He received his Ph. D. degree in Materials Science from the University of Seville-CSIC, Spain in 2013. From 1998 to 2007 he has worked as Responsible of Surface Treatments and Quality Manager at different Spanish companies in sectors such as construction, automotive and aeronautics. Since 2007 he worked as a researcher at the Institute of Materials Science of Seville.

His main research interest focus on magnetron sputtering deposition methods, mixed oxides thin films, luminescent materials and optofluidic devices.

About the author

Dr. Francisco-Javier Ferrer is a researcher National Center of Accelerators (Seville, Spain). He graduated in Physics for the University of Seville in 2001 and he got the PhD in Physics in 2007. His research focuses in the interaction of ions with matter (including ion-luminescence and basic nuclear physics) and ion beam analysis (mainly oriented to the characterization materials deposited in thin films for technological application).

He is author of more than 45 publications on peer-reviewed journals and his H-index (WoS) is 15.

About the author

Prof. Juan-Pedro Espinós is Research Professor of the Spanish National Research Council (CSIC). He was graduated in Chemistry at the University of Seville in 1985 and he received his Ph. D. in Chemistry at the same university in 1990 working on the elucidation of the so called “strong metal-support interaction effect” in catalysis. Later on, as a researcher at the Institute of Material Sciences at Seville, he focused on the deposition, characterization and processing of thin films for functional applications in catalysis, sensors, solar cells, fuel cells, optics, wear resistance, and electronics.

Currently, he is a recognized authority on the surface characterization of solids by X-ray photoelectron spectroscopy and other photoemission techniques. He has published more than 200 papers in SCI journals. He also has directed the doctoral thesis of five students.

About the author

Prof. Agustin R. González-Elipe is a Research Professor of the Spanish National Research Council (CSIC) working at the Institute of Materials Science of Seville (join centre CSIC-Univ. Seville). Director of this institute from 2000-2004, he was the responsible of the Material Science and Technology Area of CSIC. He has been active in different surface analysis and surface technology topics, both from a fundamental and an applied point of view.

His current research interest focusses in thin film and plasma technologies for the development of functional materials for sensing, monitoring and energy related applications, as well as in the use of atmospheric pressure plasmas for gas synthesis processes. He has published more than 400 research papers, holds several patents on different aspects of surface and plasma technologies and has collaborated very actively with the industry.

About the author

Dr. Francisco Yubero is research scientist of the Spanish National Research Council (CSIC) working at the Institute of Materials Science of Seville (ICMS), Spain. He received his Ph.D. degree in physics at the Universidad Autónoma de Madrid, Spain in 1993. From 1993 to 1996, he worked as a Postdoctoral Fellow at the Physics Institute of the University of Southern Denmark and at the Laboratoire pour l’Utilisation du Rayonnement Electromagnétique (LURE) in Paris, France. Since 1997 he develops his research activity at the ICMS.

His research focuses on theoretical aspects related to surface electron spectroscopies, and practical applications of nanostructured thin films. Among them, he has been involved in scientific and industrial projects related to the development of decorative coatings, ophthalmic coatings, thin film solar cells, dichroic mirrors, scintillators, fuel cells, and optical microfluidic sensors. He has published more than 180 SCI research papers on these topics.

Reference

Jorge Gil-Rostra, Francisco J. Ferrer, Juan Pedro Espinós, Agustín R. González-Elipe, Francisco Yubero. Energy-Sensitive Ion- and Cathode-Luminescent Radiation-Beam Monitors Based on Multilayer Thin-Film Designs. ACS Applied Material and Interfaces 2017, volume 9, page 16313−16320.

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