S.F. Md Ali, D. Xianling, A.S. Muhammad Noor, F.Z Rokhani, S. Hashim, M.I Saripan
Signal and Image Processing Applications (ICSIPA), 2013 IEEE International Conference on Signal and Image Processing Applications, 8 October 2013
Copyright ©2013 IEEE
Silicon photomultiplier (SiPM) technology have been introduced recently for photon detection. This type of detector offers various advantages compared to conventional photomultiplier tubes (PMTs). SiPMs are smaller in size and thus consumes less space. Several research efforts have been conducted using SiPMs for image acquisition in the field of medical imaging. The aim of this research is to model the intrinsic resolution of a scintillation camera using SiPM detectors. Experiments are conducted to determine the optimum distance between the light source and the SiPM detector to obtain an intrinsic resolution of 3.7 mm. The resolution is based on previous research using Toshiba GCA 7100A platform with Sodium Iodide (NaI) scintillator (40 x 40 x 0.9525 cm3). Results revealed that the SiPM needs to be placed at a distance of 14.36 mm from the light source to represent the scintillation camera intrinsic resolution. It is concluded that the SiPM detector can be used to model the current scintillation camera's intrinsic resolution and have a huge potential to replace the current photomultiplier tube detector.
J. J. Lee, P. Z. Y. Liu, D. R. McKenzie, N. Suchowerska
Physics in Medicine and Biology, Volume 58, Number 5
Copyright ©2013 IOP Publishing
Whenever a fibre optic is used to convey a light signal through a radiation field, it is likely that an unwanted background signal will arise from Cerenkov or fluorescent light which will contaminate the signal. In luminescence dosimetry of high energy beams, when a fibre optic is used to convey the signal from the radiation field to the detector, Cerenkov light is the dominant contributor to the background signal and must be corrected for. In this work, a novel method is demonstrated to separate the signal from the unwanted background. A remotely operated shutter is used to block the signal, allowing the residual background in the fibre optic to be quantified. This background is subtracted from the total measurement acquired in a subsequent irradiation, enabling the luminescence signal to be extracted. Two types of shutter mechanism are considered: an electro-mechanical device to intercept the light path and an LCD device to block the light by cross-polarization. Both shutters were characterized and incorporated into a fibre optic dosimetry system used to measure the radiation dose produced by external beam radiation linear accelerators. The dosimeter using each of the shutters in turn was exposed to a 6 MV photon beam to determine their performance, including the measurement of field size dependent output factors. The mechanical shutter determined the output factors to within 0.29% of those measured with an ionization chamber, whereas the LCD shutter gave results that deviated by up to 2.4%. The switching precision of both shutters was good with standard deviations of less than 0.25% and both were able to completely block the light signal when closed. The use of shutters could therefore be applied to any fibre optic based system to quantify and remove a reproducible background arising from any source including ambient, fluorescent and Cerenkov light.
J. M. Carmona, I. Podadera, J. García López, M.C. Jiménez-Ramos
Proceedings of BIW2012, Newport News, Virginia, USA
LIPAc prototype accelerator will be a 9 MeV, 125 mA continuous wave (CW) deuteron accelerator, focused on validating the technology that will be used in the future IFMIF facility. In this high power accelerator (1.125 MW), interceptive profilers are forbidden during the nominal operation. In the quest of non interceptive beam transverse profilers required for LIPAc, two prototypes based on the fluorescence of residual gas have been developed by CIEMAT. New experimental tests using 9 MeV deuterons were performed at CNA using the prototypes. Tests include injection of hydrogen, injection of nitrogen for comparison with previous results and a beam steering experiment. Hence, a brief description of the beam transverse profile prototypes together with a summary of the improved new measurements are presented.
Lakshmi Soundara-Pandian, Jarek Glodo, James F. Christian, Robert Vinci, Andrey Gueorguiev, Chad Whitney, Erik B. Johnson, Kanai S. Shah, Michael R. Squillante
Radiation Monitoring Devices, Inc. 44 Hunt Street, Watertown, MA 02472
Copyright ©2013 Institute of Nuclear Materials Management
The instrument, which is based on the new generation of scintillator materials that have the capability to discriminate gamma rays from neutrons, will simultaneously image gamma rays and neutrons. Detecting and imaging neutrons provides the ability to detect sources that are heavily shielded for gamma rays. Since few materials emit neutrons, the presence of neutrons in the image is a strong indicator of the presence of fissile material. The system would also be useful for active interrogation. This paper will discuss camera design and examine the trade-offs needed to optimize both the gamma ray and neutrons imaging systems and present measured gamma and neutron images.
J. M. Carmona, I. Podadera, A. Ibarra, A. Bocci, M.C. Jiménez-Ramos, J. García López, Z. Abou-Haïdar, M. A. G. Alvarez, B. Fernández
Physical Review Special Topics - Accelerators and Beams, Vol. 15, Issue 7
Copyright ©2012 American Physical Society
Two types of noninterceptive optical monitors, based on gas fluorescence, have been designed for use on the Linear IFMIF Prototype Accelerator (LIPAc) that is currently under development (a 125 mA, 9 MeV, 175 MHz continuous wave deuteron beam). These diagnostics offer a technique to characterize the transverse beam profile for medium to high current hadron beams, without intercepting the beam core. This paper reports on beam tests using the prototype monitors developed for LIPAc. Tests were carried out at an experimental line of the Centro Nacional de Aceleradores cyclotron, using 9 MeV deuterons with beam currents from 0.4 to 40µA. In addition, transverse beam profile measurements were performed under high background radiation (e.g. gamma dose rate up to 83mSv/h). Preliminary cross-checks with different profilers, as well as a systematic scan of beam current and vacuum pressures and tests with different injected gases (nitrogen and xenon) have been performed. In this work, we present a brief description of the experimental setup and the first measurements obtained with these prototype profilers plus a discussion of the first analysis of the background signal in a detector as a function of radiation background.
Pourandokht Naseri, David R McKenzie, Paul Liu, Simon Fleming, Natalka Suchowerska
Journal of Optics, Vol. 14 Number 10
Copyright ©2012 IOP
The irradiance – distance relation for light propagation in multimode hollow waveguides is calculated from theory and compared with measurement for visible light. These are the first measurements of this relation for square waveguides and the first for round waveguides for visible light. The square waveguides had either silvered glass surfaces or uncoated PMMA surfaces. A geometric optics method based on image formation in a kaleidoscope is used for calculations. The measurements agreed with the predictions of theory in all cases. The loss is not described by a fixed value of an attenuation coefficient as the angular divergence of the light changes with distance. At larger distances the logarithm of the irradiance is linearly dependent on the logarithm of distance, regardless of material type, surface properties and waveguide cross section. The silvered square waveguide shows the lowest measured attenuation while PMMA square waveguides constructed without any special surface preparation performed almost as well as silvered round tubes sourced commercially. The surface roughness present in the silver coating of commercially sourced round tubes compromised their performance. An array of square PMMA waveguides was used to demonstrate an application for signal transport in megavoltage radiation fields for profiling a medical radiation beam and measuring the variation of dose rate with depth in water.
A. Bortolon, W. W. Heidbrink, M. Podestà
Review of Scientific Instruments, Volume 81, 10D728, 25 October 2010
Copyright ©2010 American Institute of Physics
A second fast ion D-alpha (FIDA) installation is planned at NSTX to complement the present perpendicular viewing FIDA diagnostics. Following the present diagnostic scheme, the new diagnostic will consist of two instruments: a spectroscopic diagnostic that measures fast ion spectra and profiles at 16 radial points with 5 –10 ms resolution and a system that uses a band pass filter and photomultiplier to measure changes in FIDA light with 50 kHz sampling rate. The new pair of FIDA instruments will view the heating beams tangentially. The viewing geometry minimizes spectral contamination by beam emission or edge sources of background emission. The improved velocity-space resolution will provide detailed information about neutral-beam current drive and about fast ion acceleration and transport by injected radio frequency waves and plasma instabilities.
P. Z. Y. Liu, N. Suchowerska, P. Abolfathi, D. R. McKenzie
Medical Physics, Volume 39, Issue 4, Radiation Imaging Physics, 8 March 2012
Copyright ©2012 American Association of Physicists in Medicine
In this paper, a photomultiplier tube (PMT) array dosimetry system has been developed and tested for the real-time readout of multiple scintillation signals from fiber optic dosimeters. It provides array dosimetry with the advantages in sensitivity provided by a PMT, but without the need for a separate PMT for each detector element. The PMT array system consisted of a multianode PMT, a multichannel data acquisition system, housing and optic fiber connections suitable for clinical use. The reproducibility, channel uniformity, channel crosstalk, acquisition speed, and sensitivity of the PMT array were quantified using a constant light source. Its performance was compared to other readout systems used in scintillation dosimetry. An in vivo HDR brachytherapy treatment was used as an example of a clinical application of the dosimetry system to the measurement of dose at multiple sites in the rectum. The PMT array system was also tested in the pulsed beam of a linear accelerator to test its response speed and its application with two separate methods of Cerenkov background removal. The PMT array dosimetry system was highly reproducible with a measurement uncertainty of 0.13% for a 10 s acquisition period. Optical crosstalk between neighboring channels was accounted for by omitting every second channel. A mathematical procedure was used to account for the crosstalk in next-neighbor channels. The speed and sensitivity of the PMT array system were found be superior to CCD cameras, allowing for measurement of more rapid changes in dose rate. This was further demonstrated by measuring the dose delivered by individual photon pulses of a linear accelerator beam. The PMT array system has advantages over CCD camera-based systems for the readout of scintillation light. It provided a more sensitive, more accurate, and faster response to meet the demands of future developments in treatment delivery.
J. M. Carmona, A. Ibarra, I. Podadera, Z. Abou-Haïdar, M. A. G. Alvarez, A. Bocci, B. Fernández, J. García López, M.C. Jiménez-Ramos
Proceedings of HB2010, Morschach, Switzerland, WEO1C04
In the frame of the IFMIF-EVEDA accelerator project (a 125 mA, 9 MeV, 175 MHz (CW) deuteron accelerator) CIEMAT has designed and tested two types of non-interceptive optical monitors based on gas fluorescence. This beam diagnostic technique offers a non-invasive beam profile characterization for medium to high current hadron beams. Both monitors have been tested at CNA cyclotron using 9 MeV deuterons up to 40 µA and 18 MeV protons up to 10 µA. Profile measurements were carried out under high radiation background because the target and profilers were close to each other in the experimental setup. A Vertilon PhotoniQ IQSP482 with an SIB032 for the Hamamatsu H7260 32 channel multianode PMT was used for one of the fluorescence profile monitors (FPMs). In this paper, a brief description of FPMs together with the first beam measurements including systematic scans on beam current and pressure are presented.
M. Podestà, W. W. Heidbrink, R. E. Bell, and R. Feder
Review of Scientific Instruments, Volume 79, Number 10, October 2008
A new diagnostic, aimed at energy-resolved measurements of the spatial and temporal dynamics of fast ions in NSTX plasmas, is described. It is based on active charge-exchange recombination spectroscopy. The fast-ion signal is inferred from light emitted in the wavelength range of the D-alpha line by fast ions recombining with an injected neutral beam. Two complementary systems are operational. The first system, based on a spectrometer coupled to a charge coupled device detector, has 16 channels with space, time, and energy resolution of 5 cm, 10 ms, and 10 keV, respectively. The second system monitors the energy-integrated fast-ion signal on time scales of ~20 µs at three different radii. Signals are measured by a multianode photomultiplier tube and acquired using a Vertilon PhotoniQ IQSP480. For both systems, each channel includes two paired views, intercepting and missing the neutral beam for a direct subtraction of the background signal not associated with fast ions. Examples of signals from the 2008 NSTX run are presented.
M.R. Moser, J.M. Ryan, U. Bravar, E.O. Flückiger, J.R. Macri, M.L. McConnell
29th International Cosmic Ray Conference Pune (2005) 00, 101–104
A report on the development of a next generation solar neutron telescope that is sensitive to neutrons in the energy range 3.100 MeV, optimized to study solar neutrons in the innermost heliosphere. The detection principle is based on multiple elastic neutron-proton scatterings in plastic scintillators. By reconstructing event locations and measuring the recoil proton energies, the direction and energy spectrum of the primary neutron flux can be determined. Presented are the results of recent laboratory efforts, and in combination with simulation data, the performance of the telescope under space conditions is outlined.
McDonnell Center for the Space Sciences & Department of Physics, Washington University, St. Louis, Missouri
The performance of a multianode photomultiplier tube (MAPMT) with 64 anodes coupled to scintillating fibers is examined. Such a detector system can be used in a pair-production gamma-ray telescope as well as in other applications. The characteristics of these tubes (Hamamatsu R5900-00-M64) are presented including single photoelectron sensitivity, electrical and optical cross-talk, and dark count. Environmental test results of these devices are also presented.
L. F. Delgado-Aparicio, D. Stutman, K. Tritz, M. Finkenthal, R. Kaita, L. Roquemore, D. Johnson, R. Majeski
Review of Scientific Instruments, Volume 75, Number 10, October 2004
Copyright ©2004 American Institute of Physics
A large pixel count, fast (100 KHz) and continuously sampling soft x-ray (SXR) array for the diagnosis of magnetohydrodynamics (MHD) and turbulent fluctuations in magnetic fusion energy plasmas is being developed. The arrays are based on efficient scintillators, high throughput multiclad fiber optics, and multichannel light amplification and integration. Compared to conventional x-ray diode arrays, such systems can provide vastly increased spatial coverage, and access to difficult locations with small neutron noise and damage. An eight-channel array has been built using columnar CsI:Tl as an SXR converter and a multianode photomultiplier tube as photoamplifier. The overall system efficiency is measured using laboratory SXR sources, while the time response and signal-to-noise performance have been evaluated by recording MHD activity from the spherical tori (ST) Current Drive Experiment-Upgrade and National Spherical Torus Experiment, both at Princeton Plasma Physics Laboratory.
A. Dyshkant, D. Beznosko, G. Blazey, D. Chakraborty, K. Francis, D. Kubik, J. G. Lima, M. I. Martin, J. McCormick, V. Rykalin, V. Zutshi
Journal of Physics G: Nuclear and Particle Physics, 30 (2004) N1–N16
Copyright ©2004 IOP Publishing Ltd
The ability to distinguish between hadronic W and Z decays is one of the most challenging requirements for the future linear collider detector. Such sensitivity requires unprecedented jet energy resolution, which may be possible with energy-flow algorithms. A calorimeter that is optimized for energy-flow must have fine lateral and longitudinal segmentation. Small scintillating cells with wavelength shifting fibre readout represent an attractive basis for a digital hadron calorimeter that trades dynamic range for superior granularity, at an affordable price. Presented is the expected jet resolution for such a device, based on Monte Carlo simulations and then the initial prototyping studies is described. In particular, detailed studies are presented on cell performance under different combinations of manufacture and assembly.
R. Engels, U. Clemens, G Kemmerling, J. Schelten
Zentrallabor für Elektronik in the Forschungszentrum Juelich GmbH, Juelich, Germany
The flat-panel photomultiplier (Hamamatsu H8500) can be utilized as a high resolution area detector for thermal neutrons and high energy gamma rays. This detector type is useful for special neutron scattering experiments and for the PET applied to small animals. In various test measurements this will be demonstrated by coupling suitable scintillators (NaI, BGO, LiI single crystals, Li-glass, and LiGd-Borate) to the photocathode and by feeding the 64 output signals of the photomultiplier (PM) into an active resistor network. The four output signals from the network are transferred to the pulse processing board (UniDAQ) where the event position address is calculated and where the event storage is done by memory increment.
Proceedings of the 30th International Conference on High Energy Physics, July 27, 2000, Osaka, Japan
A 64-channel Hamamatsu H7546 Multianode Photo Multiplier Tube (MAPMT) has been evaluated as a possible choice for the photodetectors of the LHCb Ring Imaging Cherenkov detector.
Justin Peel, Nicholas Mascarenhas, Wondwosen Mengesha, Duane Sunnarborg
Nuclear Instruments and Methods in Physics Research A 556 (2006) 287–290
A directional detector for 14MeV neutrons is developed. The detector consists of an 8 x 8 array of plastic scintillating fibers coupled to a Hamamatsu H7546B multi-anode photomultiplier tube. Protons in the fibers are scattered by incident neutrons and are detected as they pass through multiple fibers. The direction of the flux of incident neutrons is determined using the energy and direction of the recoil proton. The advantages of the detector are its small size and ability to detect fast neutrons. GEANT4 was used to simulate the detector performance, and report the results of experimental studies with neutrons from a 14MeV pulsed D-T neutron generator.