Showing papers on "Photomultiplier published in 2005"
21 Jan 2005-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this paper, the absolute light yield of four different scintillation materials measured with two photomultiplier tubes and two avalanche photodiodes is presented, and the effect of optical coupling between the scintillator and detector is also discussed.
Abstract: The absolute light yield of four different scintillation materials measured with two photomultiplier tubes and two avalanche photodiodes is presented. Commonly, the photoelectron yields and electron–hole pair yields are corrected for the quantum efficiency of the detector, as specified by the manufacturer, to obtain the absolute photon yield. However, the effective quantum efficiency under scintillation measurement conditions is substantially higher due to back reflection. Only when back reflection is properly accounted for, the absolute photon yields obtained with the photomultipliers agree with those obtained with the photodiodes. The effect of optical coupling between the scintillator and detector is also discussed.
90 citations
15 Dec 2005-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: The ANTARES neutrino telescope will consist of a three-dimensional matrix of 900 large area photomultiplier tubes housed in pressure-resistant glass spheres as mentioned in this paper.
Abstract: The ANTARES neutrino telescope, to be immersed depth in the Mediterranean Sea, will consist of a three-dimensional matrix of 900 large area photomultiplier tubes housed in pressure-resistant glass spheres. The selection of the optimal photomultiplier was a critical step for the project and required an intensive phase of tests and developments carried out in close collaboration with the main manufacturers worldwide. This paper provides an overview of the tests performed by the collaboration and describes in detail the features of the photomultiplier tube chosen for ANTARES.
88 citations
TL;DR: In this paper, the spectral shapes of the response and the quantum efficiency strongly depend on the Mg-doping concentration, and a phototube with the GaN-based photocathode is realized to demonstrate a very high QE, more than 50% and sharp cutoff characteristic over three orders of magnitude.
Abstract: We have fabricated phototubes with photocathodes consisting of the Mg-doped GaN films. The spectral shapes of the response and the quantum efficiency (QE) strongly depend on the Mg-doping concentration. The calibrated QE of the photocathode is maximized to be 71.9% at a photon energy of 5.4 eV by a Mg-doping concentration of 3.0×1019cm−3. Consequently, a phototube with the GaN-based photocathode is realized to demonstrate a very high QE, more than 50% and sharp cutoff characteristic over three orders of magnitude.
87 citations
21 Feb 2005-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this paper, the authors derived a model which predicts the fraction of light impinging on a photomultiplier tube that is reflected, absorbed or transmitted, as a function of wavelength and angle, and dependent on the medium to which the photomULTiplier is coupled.
Abstract: The optical properties of the “bialkali” KCsSb and RbCsSb photomultiplier cathodes have been experimentally investigated in the visible range. The measurements carried out include the absolute reflectance at near-normal incidence, the polarization-dependent relative reflectance at various angles and the change in polarization upon reflection from the photocathode. These experimental inputs have been combined with a theoretical model to determine the complex refractive index of the photocathodes in the wavelength range (380 nm, 680 nm) and their thickness. As a result of this work, we derive a model which predicts the fraction of light impinging on a photomultiplier tube that is reflected, absorbed or transmitted, as a function of wavelength and angle, and dependent on the medium to which the photomultiplier is coupled.
86 citations
01 Jan 2005
TL;DR: In this paper, the authors showed that a 4 times4times20 mm3 LSO crystal coupled directly to the center of a 52 mm in diameter Photonis XP20D0 photomultiplier achieved a time resolution of 166plusmn5 ps, while in the case of light readout with the use of the light diffuser it degraded to 196plusmn 5 ps and 277plusmn6 ps in the center and at the edge of the PMT, respectively.
Abstract: The growing interest in time-of-flight PET triggered the study of the time resolution obtainable with a 4times4times20 mm3 LSO crystal coupled directly to the center of a 52 mm in diameter Photonis XP20D0 photomultiplier as well as the time resolution obtainable with the use of an 11 mm thick lucite light diffuser that simulates the conditions in typical PET block detectors. The LSO crystal directly coupled to the PMT yielded a time resolution of 166plusmn5 ps, while in the case of light readout with the use of the light diffuser it degraded to 196plusmn5 ps and 277plusmn6 ps in the center and at the edge of the PMT, respectively. The light diffuser was coated on the sides with black tape to absorb light and to approximate in this way the realistic performance of a future block detector. Similar time resolution was obtained by coupling the LSO crystal either to the Photonis XP20D0 PMT or to a very fast 25 mm diameter Hamamatsu R5320 PMT. These results illustrate the advantages of the very low time jitter of the Hamamatsu PMT on one side, and high quantum efficiency and a screening grid at the anode of the Photonis PMT, on the other. This study strongly suggests that time-of-flight PET based on LSO crystals is a realistic proposition for the further development
78 citations
11 Feb 2005-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: Silicon photomultiplier devices (SiPMs) were investigated as a possible front-end detector system for the electromagnetic barrel calorimeter of the GlueX Project at Jefferson Laboratory, USA, and compared against a traditional 2 in vacuum photomULTiplier tube as discussed by the authors.
Abstract: Silicon photomultiplier devices (SiPM) were investigated as a possible front-end detector system for the electromagnetic barrel calorimeter of the GlueX Project at Jefferson Laboratory, USA, and compared against a traditional 2 in vacuum photomultiplier tube. The SiPM has gain and timing resolution comparable to that of a PMT, requires a simple electronic circuit and is not sensitive to magnetic fields. These attributes allow us to conclude that it is feasible to use the SiPM as a front-end detector for this calorimeter.
78 citations
01 Jan 2005
TL;DR: In this article, a line of response (LOR) along which a photon must have originated is identified along with a position sensitive radiation detector along with the location of its origin.
Abstract: The radioactive decay of many radioisotopes generates penetrating photons capable of escaping outside the matter in which the isotopes are located From this radiation it is possible to image the spatial distribution of such isotopes inside an object However, by itself the detection of a single photon outside the body of a patient carries minimal information on the location of its origin, unless some device capable of connecting the detection with the emission location is used These devices are the optics of the imaging instrument and they identify, in combination with a position sensitive radiation detector, a line in space (the line of response, LOR) along which the photon must have originated (Fig 81A,B) The LOR data are manipulated in reconstruction software to produce three-dimensional (3D) images of the activity distribution When imaging humans, it is necessary to use photons capable of escaping undeflected from a few centimeters of tissue The energy of these photons is such that their path cannot be bent by reflection (mirrors), refraction (lenses), or diffraction as in visible light optics Nuclear scintigraphy and single photon emission computed tomography (SPECT) instrumentation resort to absorptive collimation, in which photons are selectively passed or absorbed depending on their emission location and angle of incidence on the optics The drawback of this approach is that the wide majority of photons are lost before image reconstruction For example, typical parallel-hole collimators [low energy-technetium-99m (99mTc; 140keV); general purpose] pass on the order of 1 in 10,000 (10-4) photons, but sensitivity is even lower for high-resolution and high-energy collimators, which need lower acceptance angles and thicker septa, respectively Although sensitivity can be recouped by trading off resolution (as with high-sensitivity collimators) or field-of-view (as with converging collimators), it is the concept of absorptive collimation itself that implies an inefficient use of emitted photons
76 citations
01 Apr 2005-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this article, the performance of large area avalanche photodiodes (APDs) recently developed by Hamamatsu Photonics K.K, in high-resolution X-rays and γ-rays detections was studied.
Abstract: We have studied the performance of large area avalanche photodiodes (APDs) recently developed by Hamamatsu Photonics K.K, in high-resolution X-rays and γ -rays detections. We show that reach-through APD can be an excellent soft X-ray detector operating at room temperature or moderately cooled environment. We obtain the best energy resolution ever achieved with APDs, 6.4% for 5.9 keV X-rays, and obtain the energy threshold as low as 0.5 keV measured at - 20 ∘ C . Thanks to its fast timing response, signal carriers in the APD device are collected within a short time interval of 1.9 ns (FWHM). This type of APDs can therefore be used as a low-energy, high-counting particle monitor onboard the forthcoming Pico-satellite Cute1.7. As a scintillation photon detector, reverse-type APDs have a good advantage of reducing the dark noise significantly. The best FWHM energy resolutions of 9.4 ± 0.3 % and 4.9 ± 0.2 % were obtained for 59.5 and 662 keV γ -rays, respectively, as measured with a CsI(Tl) crystal. Combination of APDs with various other scintillators (BGO, GSO, and YAP) also showed better results than that obtained with a photomultiplier tube (PMT). These results suggest that APD could be a promising device for replacing traditional PMT usage in some applications. In particular 2-dim APD array, which we present in this paper, will be a promising device for a wide-band X-ray and γ -ray imaging detector in future space research and nuclear medicine.
76 citations
TL;DR: In this article, a superconducting single-photon detector (SSPD) was proposed for counting near-infrared photons for secure quantum communications in the 1.3-to 1.55-µm range.
Abstract: We present our progress on the research and development of NbN superconducting single-photon detectors (SSPD's) for ultrafast counting of near-infrared photons for secure quantum communications. Our SSPD's operate in the quantum detection mode based on the photon-induced hotspot formation and subsequent development of a transient resistive barrier across an ultrathin and submicron-width superconducting stripe. The devices are fabricated from 4-nm-thick NbN films and kept in the 4.2- to 2-K temperature range. The detector experimental quantum efficiency in the photon-counting mode reaches above 40% for the visible light and up to 30% in the 1.3- to 1.55-µm wavelength range with dark counts below 0.01 per second. The experimental real-time counting rate is above 2 GHz and is limited by our readout electronics. The SSPD's timing jitter is below 18 ps, and the best-measured value of the noise-equivalent power (NEP) is 5 × 10–21 W/Hz1/2 at 1.3 µm. In terms of quantum efficiency, timing jitter, and maximum counting rate, our NbN SSPD's significantly outperform semiconductor avalanche photodiodes and photomultipliers in the 1.3- to 1.55-µm range. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
76 citations
21 Mar 2005-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this paper, the authors report on the design, construction and performance of a prototype for a high-granularity tile hadronic calorimeter for a future international linear collider detector.
Abstract: We report on the design, construction and performance of a prototype for a high-granularity tile hadronic calorimeter for a future international linear collider detector. Scintillating tiles are read out via wavelength-shifting fibers that guide the scintillation light to a novel photodetector, the silicon photomultiplier. A prototype has been tested using a positron test beam at DESY. The results are compared with a reference prototype calorimeter equipped with multichannel vacuum photomultipliers. Detector calibration, noise, linearity and stability are discussed, and the energy response in a 1–6 GeV positron beam is compared with simulations. The present results demonstrate that the silicon photomultiplier is well-suited as photodetectors in calorimeters and thus has been selected for the construction of a 1 m 3 calorimeter prototype to operate in hadron beams.
73 citations
21 Nov 2005-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this article, the properties of CaWO4 (CaWO) crystals in γ-spectrometry were studied at room and liquid nitrogen (LN2) temperatures.
Abstract: The properties of CaWO4 (CaWO) crystals in γ-spectrometry were studied at room and liquid nitrogen(LN2) temperatures. Two small samples of 10×10×4 mm3 and 10×10×8 mm3 size were tested, coupled to a Photonis XP3212 photomultiplier at room temperature and a large area avalanche photodiode at LN2 temperature. Light pulse shape and light output at room and LN2 temperatures were measured. Energy resolution and non-proportionality of the CaWO response versus γ-ray energy were studied and compared with those of small BGO and CdWO4 crystals to discuss further the origin of the intrinsic resolution of undoped scintillating crystals. A high light output of 4800±200 phe/MeV and a good energy resolution of 6.6±0.2% for 662 keV γ-rays from a 137Cs source were measured for the small samples coupled to the XP3212 photomultiplier.
TL;DR: In this paper, the authors describe the multichannel implementation of an intensity modulated optical tomography system developed at Helsinki University of Technology, where the gain of the photomultiplier tubes (PMTs) is individually adjusted during the measurement sequence to increase the dynamic range of the system by 104.
Abstract: In this article, we describe the multichannel implementation of an intensity modulated optical tomography system developed at Helsinki University of Technology. The system has two time-multiplexed wavelengths, 16 time-multiplexed source fibers and 16 parallel detection channels. The gain of the photomultiplier tubes (PMTs) is individually adjusted during the measurement sequence to increase the dynamic range of the system by 104. The PMT used has a high quantum efficiency in the near infrared (8% at 800nm), a fast settling time, and low hysteresis. The gain of the PMT is set so that the dc anode current is below 80nA, which allows the measurement of phase independently of the intensity. The system allows measurements of amplitude at detected intensities down to 1fW, which is sufficient for transmittance measurements of the female breast, the forearm, and the brain of early pre-term infants. The mean repeatability of phase and the logarithm of amplitude (lnA) at 100MHz were found to be 0.08° and 0.004, res...
TL;DR: A neutron scintillation detector based on a position-sensitive photomultiplier has been developed for neutron spin echo and small angle neutron scattering measurements.
Abstract: A neutron scintillation detector based on a position-sensitive photomultiplier has been developed for neutron spin echo and small angle neutron scattering measurements. This photomultiplier has good spatial resolution, less than 1 mm2. The detection efficiency of gamma ray background is very low for using a thin ZnS/6LiF scintillator. The effective area of this detector is around 60 cm2.
01 Jan 2005
TL;DR: In this article, the use of a silicon photomultiplier for radiation detection and gamma spectroscopy was reported, where the authors measured gain of up to 106, and pixel dark count rate of a few MHz related to the leakage current of about 1 muA.
Abstract: Silicon photomultipliers are of great interest for scintillation light detection in gamma spectroscopy, due to their large gain and high speed. In this article we report about the use of a silicon photomultiplier for radiation detection and gamma spectroscopy. It is our goal to understand silicon photomultipliers to the extent that we could use them in imaging instrumentation for applications in nuclear medicine. We measure gain of up to 106, and pixel dark count rate of a few MHz related to the leakage current of about 1 muA. Using an LED pulser, we measure the signal risetime of less than a few nano-seconds, and 300-ps rms jitter relative to a photomultiplier tube. We use CsI:Tl and LSO:Ce scintillators and measure energy spectra from radionuclides. In CsI:Tl we measure an energy resolution of 32% FWHM at 122 keV from Co-57, and extrapolate a resolution of 30% FWHM at 140 keV. We observe reasonably good energy spectra from LSO:Ce scintillators. Similar energy spectra were obtained with a photomultiplier tube as a reference
01 Mar 2005-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this paper, the authors report on measurements of the gain, efficiency, linearity, crosstalk, and dark noise of 232 of these PMTs, of which 219 met MINOS requirements.
Abstract: Hamamatsu R5900-00-M64 and R7600-00-M64 photomultiplier tubes will be used with wavelength-shifting optical fibres to read out scintillator strips in the MINOS near detector. We report on measurements of the gain, efficiency, linearity, crosstalk, and dark noise of 232 of these PMTs, of which 219 met MINOS requirements.
TL;DR: In this article, a non-destructive and sensitive monitor consisting of photocathode wire grids arranged in an XY configuration for measuring the spatial profile, divergence, and intensity of pulsed UV, x-ray, and charged particle beams is described.
Abstract: A nondestructive and sensitive monitor consisting of photocathode wire grids arranged in an XY configuration for measuring the spatial profile, divergence, and intensity of pulsed UV, x-ray, and charged particle beams is described. The monitor has been used to measure laser beams at wavelengths λ=213−532nm, and antiproton, proton, H− ions, and electron beams of energies E=50eV to 5 MeV.
11 Sep 2005-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this article, the Hamamatsu R7525HA PMT was used to detect the Cherenkov light generated in quartz fibers embedded in the CMS-HF Forward Calorimeter.
Abstract: Approximately 2000 PMTs will be used to detect the Cherenkov light generated in quartz fibers embedded in the CMS-HF Forward Calorimeter. The Hamamatsu R7525HA PMT was chosen for this purpose. We measured the transit time, transit time spread, pulse width, rise time, anode dark current, and relative gain for each tube in the test station at the University of Iowa. Life-time, gain versus high voltage, and single photoelectron spectrum measurements were also done on a small sample of PMTs. All the tubes were tested to verify that they conform to the HF requirements.
TL;DR: The first in vivo real-time dynamic spectral measurements showing tissue oxygenation changes in the arm of a human subject and the performance in terms of accuracy, linearity, noise sensitivity, stability, and reproducibility are presented.
Abstract: We present a detailed characterization of a system for fast time-resolved spectroscopy of turbid media based on supercontinuum generation in a photonic crystal fiber. The light source provides subpicosecond pulses in the 550–1000-nm spectral range, at 85 MHz, at an average power of up to 50 mW. Wavelength-resolved detection is accomplished by means of a spectrometer coupled to a 16-channel, multianode photomultiplier tube, giving a resolution of 4.5–35 nm/channel, depending on the grating. Time-dispersion curves are acquired with time-correlated single-photon counting, and absorption and reduced scattering coefficients are determined by fitting the data to the diffusion equation. We characterized the system by measuring the time-resolved diffuse reflectance of epoxy phantoms and by assessing the performance in terms of accuracy, linearity, noise sensitivity, stability, and reproducibility. The results were similar to those from previous systems, whereas the full-spectrum (6103810 nm) acquisition time was as short as 1 s owing to the parallel acquisition. We also present the first in vivo real-time dynamic spectral measurements showing tissue oxygenation changes in the arm of a human subject.
01 Jan 2005
TL;DR: In this article, FWHM was recorded with -photomultiplier (PMT) and -PMT detectors operating in coincidence using 511 keV positron annihilation gamma-ray pairs.
Abstract: —FWHM) has been recorded with -photomultiplier (PMT) and -PMT detectors operating in coincidence using 511 keV positron annihilation gamma-ray pairs.
Patent•
05 Dec 2005
TL;DR: In this article, a photomultiplier tube (PMT) or other photo-detector with electron multiplication gain was used to achieve accurate light measurement in a luminescent radiation dosimeter reader.
Abstract: Methods and means for measuring and adjusting the gain of a photomultiplier tube (PMT), or other photo-detector with electron multiplication gain, for the purpose of achieving accurate light measurement, such as in a luminescent radiation dosimeter reader. With a PMT illuminated by a light emitting diode or other light source, the PMT output signal is measured in two modes, signal integration and photon pulse counting. The measured PMT gain is calculated as the ratio of the integrated signal to the photon pulse count. The PMT high voltage may be adjusted to cause the measured PMT gain to correspond to an established calibration gain value, or the data from the PMT may be adjusted to compensate the deviation of the measured PMT gain from the calibration gain value. The light source may be a controllable light source that can be adjusted to provide a specific photon count rate output as measured by the PMT. This invention provides for maintaining light measurement calibration without requiring temperature stabilization or a fixed light source.
01 Dec 2005-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this article, the results obtained with a new generation portable gamma camera, assembled with an innovative technique based on CsI(Tl) scintillation crystals inserted into the square holes of a tungsten collimator, have been evaluated with particular attention to pixel identification capability.
Abstract: This work presents the results obtained with a new generation portable gamma camera, assembled with an innovative technique based on CsI(Tl) scintillation crystals inserted into the square holes of a tungsten collimator Characterization measurements have been performed on three detectors with different crystal size, in order to obtain 7×7, 8×8 and 9×9 arrays over the fixed area of 257×257 mm 2 , having the same overall dimensions of a Position Sensitive Photomultiplier Tube Detector sensitivity, energy resolution and spatial resolution have been measured , and the acquired image quality has been evaluated with particular attention to pixel identification capability
01 Dec 2005-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this article, the optical properties of the Sudbury Neutrino Observatory (SNO) heavy water Cherenkov neutrino detector are measured in situ using a light diffusing sphere (laserball) connected to a pulsed nitrogen/dye laser via specially developed underwater optical fibre umbilical cables.
Abstract: The optical properties of the Sudbury Neutrino Observatory (SNO) heavy water Cherenkov neutrino detector are measured in situ using a light diffusing sphere (“laserball”). This diffuser is connected to a pulsed nitrogen/dye laser via specially developed underwater optical fibre umbilical cables. The umbilical cables are designed to have a small bending radius, and can be easily adapted for a variety of calibration sources in SNO. The laserball is remotely manipulated to many positions in the D2O and H2O volumes, where data at six different wavelengths are acquired. These data are analysed to determine the absorption and scattering of light in the heavy water and light water, and the angular dependence of the response of the detector’s photomultiplier tubes. This paper gives details of the physical properties, construction, and optical characteristics of the laserball and its associated hardware.
21 Jun 2005-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this paper, the authors report results of the characterization of over 1600 multi-anode R5900-00-M16 photomultipliers manufactured by Hamamatsu Photonics and installed in the MINOS Far detector.
Abstract: We are reporting results of the characterization of over 1600 multi-anode R5900-00-M16 photomultipliers manufactured by Hamamatsu Photonics K.K., and installed in the MINOS Far detector. We have conducted extensive tests of the uniformity of gain and collection efficiency of individual anodes, the cross-talk among all 16 channels, the dark noise, and the linearity of response. In our studies we used a blue light-emitting diode to illuminate phototubes through 1.2 mm diameter optical fibers. In this paper, we present summaries of the main characteristics of the tested photomultipliers.
17 Mar 2005
TL;DR: The output pulse width in the time response of photo-multiplier tubes (PMT) is much faster in micro-channel plate (MCP) models compared to more standard dynode chain PMTs due to a vastly reduced variation in the path length of the electrons through the amplifying system as discussed by the authors.
Abstract: The output pulse width in the time response of photo-multiplier tubes (PMT) is much faster in micro-channel plate (MCP) models compared to more standard dynode chain PMTs due to a vastly reduced variation in the path length of the electrons through the amplifying system. Typically the pulse widths can be in the region of 200ps compared to the nanosecond domain occupied by the best conventional PMTs. Photek manufacture PMTs with one, two or three MCPs depending on the gain required, and also use the same structure without any MCPs to work as simple photodiodes. We demonstrate the variation of output pulse characteristics due to the number and design of MCPs in a range of PMT models and illustrate the importance of having a properly designed 50ohm transmission line to deliver the pulse from the detector.
TL;DR: A novel design in which the detection crystal is divided into a number of layers along its length with an avalanche photo diode (APD) inserted between each layer with potential advantages of improved light collection efficiency, reduced dependency on dense crystal to achieve good stopping power, and ease of crystal manufacture are presented.
Abstract: Scintillation detectors developed for PET traditionally use relatively thick crystals coupled to photomultiplier tubes. To ensure good efficiency the crystals typically measure between 10 and 30 mm thick. Detectors also require good spatial resolution so the scintillator is normally made up of a densely packed array of long thin crystals. In this paper, we present a novel design in which the detection crystal is divided into a number of layers along its length with an avalanche photo diode (APD) inserted between each layer. With thin layers of crystal, it is possible to use a continuous rather than a pixelated crystal. The potential advantages of this design over a conventional PMT-based detector are: (i) improved light collection efficiency, (ii) reduced dependency on dense crystal to achieve good stopping power, (iii) ease of crystal manufacture, (iv) reduced detector dead-time and increased count rate, and (v) inherent depth of interaction. We have built a four-layer detector to test this design concept using Hamamatsu S8550 APD arrays and LYSO crystals. We used the centre 16 pixels of each of the arrays to give an active area of 9.5 mm × 9.5 mm. Four crystals 9.5 mm × 9.5 mm were used with thickness increasing from 2 mm at the front to 2.5 mm, 3.1 mm and 4.3 mm at the back, to ensure a similar count rate in each layer. Calculations for the thickness of the four layers were initially made using the linear attenuation coefficient for photons at 511 keV of LYSO. Experimental results and further simulation demonstrated that a correction to the thickness of each layer should be considered to take into account the scattered events. The energy resolution for each of the layers at 511 keV was around 15%, coincidence-timing resolution was 2.2 ns and the special resolution was less than 2 mm using a statistical-based positioning algorithm.
TL;DR: In this article, the authors improved the energy resolution of a vacuum ultraviolet isochromat spectrometer for inverse photo-emission spectroscopy by adding a gas chamber with two CaF2 windows at the entrance of the counting tube.
Abstract: We have significantly improved the energy resolution of a vacuum ultraviolet isochromat spectrometer for inverse photoemission spectroscopy. The detector is based on a Geiger–Muller counting tube with acetone as filling gas and a CaF2 entrance window working as an energy selective optical bandpass at a mean energy of 9.84eV. Under this operating conditions the detector achieves an optical energy resolution of 320meV (FWHM). By adding a gas chamber with two CaF2 windows at the entrance of the counting tube we are able to use absorption lines of oxygen and krypton to further enhance the optical resolution of the detector system. In the case of krypton the mean energy shifts to a somewhat lower value of 9.72eV. The energy resolution improves to about 115meV (FWHM), while the integrated sensitivity decreases to approximately 30%. Due to the ability to easily switch between high sensitivity and high resolution this new counting tube differs from other resolution-enhancing suggestions. Measurements on the promi...
15 Dec 2005-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this article, the properties of a time-of-flight scintillator bar, EJ-200, wrapped with different reflective materials, were studied using 800MeV/c electron beam at the test beam of IHEP in China.
Abstract: The properties of a time-of-flight scintillator bar, EJ-200, wrapped with different reflective materials, were studied using 800MeV/c electron beam at the test beam of IHEP in China. It is 230 cm long with a cross-section of 5 x 6 cm 2, viewed from both ends by R5924 photomultiplier tubes. The results show that the time resolution and the attenuation length depend on the reflective materials. (c) 2005 Elsevier B.V. All rights reserved.
01 Feb 2005-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: A facility to test the photomultiplier tubes (PMTs) for the solar neutrino detector Borexino was built at the Gran Sasso laboratory as discussed by the authors.
Abstract: A facility to test the photomultiplier tubes (PMTs) for the solar neutrino detector Borexino was built at the Gran Sasso laboratory. Using the facility 2200 PMTs with optimal characteristics were selected from the 2350 delivered from the manufacturer. The details of the hardware used are presented.
TL;DR: In this article, a small prototype of a camera based on a monolithic array of silicon drift detectors (SDDs) used as photodetectors for a single CsI(Tl) scintillator crystal is presented.
Abstract: In this work we present a small prototype of Anger camera based on a monolithic array of silicon drift detectors (SDDs) used as photodetectors for a single CsI(Tl) scintillator crystal. This prototype, having a total sensitive area of about 1cm2, has been realized in order to evaluate the performances attainable in γ-ray imaging by using a SDD array instead of the more conventionally employed photomultiplier tubes. An intrinsic resolution better than 200μm has been measured with this camera. This result was achieved thanks to the extremely low electronics noise presented by the SDD units, fully exploited by the integration of the front-end junction field effect transistor directly on the detector chip. The main features of the detector as well as the results of its extended experimental characterization with 60 and 122 keV gamma rays are presented and discussed in the article. The present device has many potential applications in the field of medical imaging, in which outstanding position resolutions are ...
Patent•
30 Mar 2005TL;DR: A radiation detector includes a housing, a crystal and a photomultiplier tube supported in the housing as discussed by the authors, and a plurality of elongated, flat plastic or ceramic springs are located radially between the crystal and the tube.
Abstract: A radiation detector includes a housing, a crystal and a photomultiplier tube supported in the housing A plurality of elongated, flat plastic or ceramic springs are located radially between the crystal and photomultiplier tube and the housing, and at least one additional spring is located at one end of the crystal