Search query: improve LSO light output

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abstract: Photonic crystals (PhCs) are optical materials which can affect the propagation of light in multiple ways. In recent years PhCs contributed to major technological developments in the field of semiconductor lasers, light emitting diodes and photovoltaic applications. In our case we are investigating the capabilities of photonic crystal slabs with the aim to improve the performance of heavy inorganic scintillators. To study the combination of scintillators and PhCs we use a Monte Carlo program to simulate the light propagation inside a scintillator and a rigorous coupled wave analysis (RCWA) framework to analyse the optical PhC properties. The simulations show light output improvements of a wide range of scintillating materials due to light scattering effects of the PhC slabs. First samples have been produced on top of 1.2 x 2.6 x 5 mm LSO (cerium doped Lutetium Oxyorthosilicate, Lu2SiO5:Ce3+ scintillators using electron beam lithography and reactive ion etching (RIE) Our samples show a 30 60% light output improvement when compared to unstructured reference crystals which is in close accordance with our simulation results. In addition, a theoretical investigation of the restrictions of the current PhC sample is given which concludes with prospects for improved future designs.
author_names: Arno Knapitsch

Etiennette Auffray

Christian Wolfgang Fabjan

Jean Louis Leclercq

Xavier Letartre

Radoslaw Mazurczyk

Paul Lecoq
title: Effects of Photonic Crystals on the Light Output of Heavy Inorganic Scintillators
venue: IEEE Transactions on Nuclear Science
year: 2013

abstract: UV and /spl gamma/ ray excited luminescence and nuclear spectroscopy were used to study the relationship between the scintillation mechanisms of LSO and the spectroscopic characteristics obtained with PMT and APD readouts at room temperature. No correlation was found between scintillation decay time and light output. Like other investigators, we observed the existence of two distinct luminescence centers, Ce1 and Ce2, that mainly give rise to short (420 nm) and long (440 nm) emission wavelengths. Our measurements showed that different LSO crystals excited by /spl gamma/ rays have emission spectra with largely different shapes and maxima depending on the relative population and luminescence efficiency of these centers. It was also found that the poor energy resolution of LSO and YSO scintillators is well correlated with the coexistence of the two competing luminescence mechanisms. The prevalence of either Ce1 or Ce2 luminescence tends to reduce the variance of light emission and, thus, to improve energy resolution. Inversely, the coexistence of the two centers increases variance and degrades energy resolution.
author_names: A Saoudi

Catherine M Pepin

Daniel Houde

Roger Lecomte
title: Scintillation light emission studies of LSO scintillators
venue: 1998 IEEE Nuclear Science Symposium Conference Record. 1998 IEEE Nuclear Science Symposium and Medical Imaging Conference (Cat. No.98CH36255)
year: 1998

abstract: In order to improve image quality in Positron Emission Tomography (PET) different routes are being pursued such as fast timing resolution for time of flight PET, higher spatial resolution by the use of smaller scintillator pixels and the use of depth of interaction information. The detection of the depth of interaction (DOI) of a gamma ray within a detector, deploying pulse shape discrimination (PSD) has been used to increase sensitivity and spatial resolution, especially at the edge of the field of view (FOV) The DOI information is used to reduce the parallax error; thus improving spatial resolution. Commonly, different scintillator materials with different decay times and light output and other differentiating factors, such as density, emission spectra, etc. are used for DOI detectors. We present a multilayer phoswich detector comprised of LSO with different decay times in the range from 30 ns to 47 ns. The difference in decay times is achieved by co doping LSO:Ce with Ca, resulting in short decay times of ~30 ns. The use of a cut light guide allows the use of regular Photomultiplier tubes, giving the opportunity of a potential DOI detector replacement for current detectors. We were able to identify each pixel in the different detector layers and thus, to determine the depth of the photon interaction and achieve a timing resolution of 345 ps.
author_names: Florian Bauer

Mehmet Aykac

Lars I Eriksson

Matthias J Schmand
title: Depth of Interaction With a 3 Dimensional Checkerboard Arrangement LSO LSO Block
venue: IEEE Transactions on Nuclear Science
year: 2010

abstract: To improve the spatial resolution and uniformity in modern high resolution brain PET systems over the entire field of view (FOV) it is necessary to archive the depth of interaction (DOI) information and correct for spatial resolution degradation. In this work the authors present the performance results of a high resolution LSO/GSO phoswich block detector with DOI capability. This detector design will be used in the new CTI High Resolution Research Tomograph, ECAT HRRT. The two crystal layer (19/spl times/19/spl times/7.5 mm/sup 3/ and a light guide are stacked on each other and mounted on a (2/spl times/2) PMT set, so that the corners of the phoswich are positioned over the PMT centers. The crystal phoswich is cut into a 8/spl times/8 matrix of discrete crystals. The separation of the LSO and the GSO layer by pulse shape discrimination allows discrete DOI information to be obtained. The high light output and the light guide design results in an accurate identification of the 128 single crystals per block. Flood source measurements document a very good homogeneity of events, energy centroid stability and energy resolution (14 20% FWHM) per single crystal. An intrinsic resolution of /spl sim/1.3 mm and the DOI feasibility is extracted by coincidence measurements with a single GSO crystal.
author_names: Matthias J Schmand

Lars A Eriksson

Michael E Casey

Mark S Andreaco

Charles L Melcher

Klaus Wienhard

Gerd Flugge

Ronald Nutt
title: Performance results of a new DOI detector block for a high resolution PET LSO research tomograph HRRT
venue: 1997 IEEE Nuclear Science Symposium Conference Record
year: 1997

abstract: To improve the spatial resolution and uniformity in modern high resolution brain PET systems over the entire field of view (FOV) it is necessary to archive the depth of interaction (DOI) information and correct for spatial resolution degradation. In this work the authors present the performance results of a high resolution LSO/GSO phoswich block detector with DOI capability. This detector design will be used in the new CTI High Resolution Research Tomograph, ECAT HRRT. The two crystal layer (19/spl times/19/spl times/7.5 mm/sup 3/ and a light guide are stacked on each other and mounted on a (2/spl times/2) PMT set, so that the corners of the phoswich are positioned over the PMT centers. The crystal phoswich is cut into a 8/spl times/8 matrix of discrete crystals. The separation of the LSO and the GSO layer by pulse shape discrimination allows discrete DOI information to be obtained. The high light output and the light guide design results in an accurate identification of the 128 single crystals per block. Flood source measurements document a very good homogeneity of events, energy centroid stability and energy resolution (14 20% FWHM) per single crystal. An intrinsic resolution of /spl sim/1.3 mm and the DOI feasibility is extracted by coincidence measurements with a single GSO crystal.
author_names: Matthias J Schmand

Lars A Eriksson

Michael E Casey

Mark S Andreaco

Charles L Melcher

Klaus Wienhard

Gerd Flugge

Ronald Nutt
title: Performance results of a new DOI detector block for a high resolution PET LSO research tomograph HRRT
year: 1997

abstract: Superlattice InAs/GaSb light emitting diodes with peak emission wavelength of 8.6 mm and output power approaching 190 mW at 77 K from a 120 x 120 mm2 mesa are demonstrated. Output power in excess of 600 m.W was demonstrated from a 520 x 520 mm mesa at 1 A drive current and 50% duty cycle. Devices were grown by molecular beam epitaxy on lightly n doped GaSb substrates and employed a 16 stage cascaded active region configuration to improve current efficiency and increase optical output. Emitting regions were coupled by semi metallic tunnel junctions consisting of a p GaSb layer and a thickness graded InAs/GaSb superlattice stack.
author_names: Edwin John Koerperick

Dennis T Norton

Jonathon T Olesberg

B V Olson

John P Prineas

Thomas F Boggess
title: Cascaded Superlattice InAs/GaSb Light Emitting Diodes for Operation in the Long Wave Infrared
venue: IEEE Journal of Quantum Electronics
year: 2011

abstract: Novel approach to improve the light extraction efficiency of InGaN quantum wells light emitting diodes (LEDs) using SiO2 microspheres was presented, leading to ~232% increase of the LEDs output power.
author_names: Yik-Khoon Ee

Pisist Kumnorkaew

Ronald A Arif

James F Gilchrist

Nelson Tansu
title: Enhancement of Light Extraction Efficiency of InGaN Quantum Wells LEDs Using SiO2 Microspheres
venue: 2007 Conference on Lasers and Electro Optics (CLEO)
year: 2007

abstract: As time of flight PET (TOF PET) gains popularity in clinical diagnostic, the coincidence timing resolution of PET systems becomes more crucial. The most common scintillators for commercial TOF PET systems are Lu based ones such as LSO or LYSO for their high light output, high density and fast decay time. Recently, LGSO with 0.025% Ce (LGSO fast) was developed which has faster decay time than LGSO with Ce concentration of 0.1 mol% (LGSO standard) Using the LGSO fast in conjunction with silicon photomultiplier (Si PM) may improve the timing performance for the development of TOF PET systems. Consequently, we tested the basic performance of LGSO fast and coupled them with Si PMs to measure the coincidence timing resolution using a high bandwidth digital oscilloscope. The performance was also evaluated for LGSO standard and other Lu based scintillators such as lutetium fine silicate (LFS) and two types of LYSOs from other manufacturers. The light output was largest for one of the LYSO from one manufacture and smallest for the LYSO from other manufacture. Decay time was fastest for LGSO fast (33.8 ns) and slowest for one of the LYSO (39.9 ns) Coincidence timing resolution for 2.9 mm long Lu based scintillators, LGSO fast was the best (156.5 ps) and one of the LYSO showed the worst (235.1 ps) For the 20 mm long scintillators, coincidence timing resolution was also best for LGSO fast (273.2 ps) and worst for one of the LYSO (481.8 ps) We conclude that LGSO fast combined with Si PM showed best timing performance among measured Lu based scintillators. Also within the same Lu based scintillators such as LYSOs, we found that the performance differences were sometimes significant and quality control of the Lu based scintillator is essential to achieve good performance in PET systems.
author_names: Seiichi Yamamoto

Satoshi Okumura

Natsuki Kato

J Y Yeom
title: Timing measurements of lutetium based scintillators combined with silicon photomultipliers for TOF PET system
year: 2015

abstract: 1 Introduction 12 The CAPTAIN Detector 42.1 Cryostats 52.2 Cryogenics 62.3 Electronics 72.4 TPC 72.4.1 CAPTAIN TPC 72.4.2 Prototype TPC 92.5 Photon Detection System 92.6 Laser Calibration System 102.7 Special Run Modes 112.7.1 Tests of Doping Liquid Argon to Improve Light Output 113 Neutrons 123.1 Physics Importance 123.2 High intensity neutron running 143.3 Low intensity neutron running 153.3.1 Low energy neutron run 153.3.2 High energy neutron run 153.4 Run Plans 164 Neutrinos 174.1 Running at NuMI 174.1.1 On axis running in NuMI 174.1.2 O axis running in NuMI 204.2 Running at the SNS 204.3 Stopped Pion Source at the BNB 234.4 Other Neutrino Possibilities 245 Conclusions 251
author_names: The Captain Collaboration H Berns

Hongsheng Chen

David B Cline

J R Danielson

Z Djurcic

Stephen R Elliott

Gerald T Garvey

Victor M Gehman

Christopher Grant

Elena Guardincerri

Richard W Kadel

Thomas Kutter

D Lee

Kwang-ryeol Lee

Q P Liu

W C Louis

Christopher Michael Mauger

C Mcgrew

Robert McTaggart

J Medina

William J Metcalf

Geoffrey B Mills

Jacqueline Mirabal-Martinez

Stuart Lee Mufson

Emilija Pantic

O Prokofiev Mufson

Veljko Radeka

J Ramsey

Keith Rielage

Himansu Sahoo

Constantine Sinnis

Michael Burghard Smy

Walter Sondheim

Ion Alexandru Stancu

Robert C Svoboda

Matthew Szydagis

C Taylor

A Teymourian

Craig E Thorn

Craig E Tull

Martin Tzanov

Rick van de Water

H G Wang

Chiaki Yanagisawa

A Yarritu

C Zhang
title: The CAPTAIN Detector and Physics Program
year: 2013

abstract: Relevant information in positron emission tomography is currently being obtained mostly by analog signal processing methods. New digital PET scanner architectures are now becoming available, which offer greater flexibility and easier reconfiguration capability as compared to previous PET designs. Moreover, new strategies can be devised to extract more information with better accuracy from the digitized detector signals. Trained artificial neural networks (ANN) have been investigated to improve coincidence timing resolution with different types of Avalanche PhotoDiode (APD) based detectors. The signal at the output of a charge sensitive preamplifier was digitized with an off the shelf, free running 100 MHz, 8 bit analog to digital converter and time discrimination was performed with ANNs implemented in field programmable gate array (FPGA) Results show that ANNs can be particularly efficient with slow and low light output scintillators, such as BGO, but less so with faster luminous crystals, such as LSO. In reference to a fast PMT plastic detector, a time resolution of 6.5 ns was achieved with a BGO APD detector. With LSO, the ANN was found to be competitive with other digital techniques developed in previous works. ANNs implemented in FPGAs provide a fast and flexible circuit that can be easily reconfigured to accommodate various detectors under different signal/noise conditions.
author_names: Jean-Daniel Leroux

D Rouleau

Catherine M Pepin

J -B Michaud

Jules Cadorette

Rejean Fontaine

Roger Lecomte
title: Time Discrimination Techniques Using Artificial Neural Networks for Positron Emission Tomography
venue: IEEE Transactions on Nuclear Science
year: 2009