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The present study focuses on the determination of the optimal crystal thickness of LaCl3:Ce and LaBr3:Ce crystal scintillators for Nuclear Medicine Imaging applications. A theoretical model was applied for the estimation of the optical efficiency of the two single-crystal scintillators in terms of Detector Optical Gain (DOG). The theoretical model was validated against the experimental values of the Absolute Efficiency (AE) of the two crystals, obtained in the energy range 110 kVp–140 kVp. By fitting the theoretical model to these experimental data, the propagation probability per elementary thickness k was determined and DOG was theoretically calculated for crystal thicknesses from 0.005 cm to 2 cm, in the energy range of Nuclear Medicine Imaging. k values for LaCl3:Ce and LaBr3:Ce crystals were significantly higher compared to other single-crystal scintillators. The DOG values of the two crystals may serve as evidence that the LaBr3:Ce crystal exhibits significantly better performance compared to the LaCl3:Ce crystal. With an increase in energy, the optimum thickness increases for both crystals. Additionally, crystal efficiency generally demonstrates a decrease beyond a certain thickness. The aforementioned insights may provide valuable guidance for the design and optimization of crystal scintillators in Nuclear Medicine Imaging systems. [ABSTRACT FROM AUTHOR]

The present study focuses on the determination of the optimal crystal thickness of LaCl3:Ce and LaBr3:Ce crystal scintillators for Nuclear Medicine Imaging applications. A theoretical model was applied for the estimation of the optical efficiency of the two single-crystal scintillators in terms of Detector Optical Gain (DOG). The theoretical model was validated against the experimental values of the Absolute Efficiency (AE) of the two crystals, obtained in the energy range 110 kVp–140 kVp. By fitting the theoretical model to these experimental data, the propagation probability per elementary thickness k was determined and DOG was theoretically calculated for crystal thicknesses from 0.005 cm to 2 cm, in the energy range of Nuclear Medicine Imaging. k values for LaCl3:Ce and LaBr3:Ce crystals were significantly higher compared to other single-crystal scintillators. The DOG values of the two crystals may serve as evidence that the LaBr3:Ce crystal exhibits significantly better performance compared to the LaCl3:Ce crystal. With an increase in energy, the optimum thickness increases for both crystals. Additionally, crystal efficiency generally demonstrates a decrease beyond a certain thickness. The aforementioned insights may provide valuable guidance for the design and optimization of crystal scintillators in Nuclear Medicine Imaging systems.

The response of a gamma-ray spectrometer is generally determined by analyzing full-energy peaks. However, full-energy peaks cannot be measured easily in the case of scintillation detectors that consist of light elements, such as glass scintillators. Only a strong Compton plateau appears in the spectrum of such detectors. Therefore, Compton edgers were used to evaluate the response of these detectors. The response of a low-resolution 6 Li-glass detector to gamma rays was measured for the first time by a coincidence method with a high-resolution LaBr 3 :Ce detector using cascade gamma rays (2.75 and 1.37 MeV) from a 24Na source. Coincidence gates were applied at the peaks of the spectrum of the LaBr 3 :Ce detector at the 0.51 MeV annihilation peak, and the sum peaks of a gamma ray and a backscattered gamma ray. By analyzing the gated spectra of the 6 Li-glass detector, the energy-dependent detector response (i.e., the output strength and its dispersion) was determined. • Evaluation of the response characteristics, including signal output and broadening, of a low-resolution 6Li-glass detector to gamma rays up to approximately 2.5 MeV. • Coincidence measurement of cascade gamma rays emitted from a 24Na source with a high-resolution detector, a LaBr 3 :Ce detector. • Peak analysis of the spectra of the 6Li-glass detector gated at gamma ray peaks of the LaBr3:Ce detector. [ABSTRACT FROM AUTHOR]

In the present study, the response of the crystalline scintillator LaBr3:Ce when excited with X-rays at tube voltages from 50 kVp to 150 kVp was investigated, for possible use in hybrid medical-imaging systems. A single crystal (10 × 10 × 10 mm3) was irradiated by X-rays within the aforementioned tube-voltage range, and the absolute efficiency (AE), as well as the detective quantum efficiency for zero spatial-frequency (DQE(0)), were measured. The energy-absorption efficiency (EAE), the quantum-detection efficiency (QDE) and the spectral compatibility with various optical photodetectors were also calculated. The results were compared with the published data for the LaCl3:Ce, Bi4Ge3O12 (BGO), Lu2SiO5:Ce (LSO), and CdWO4 single crystals of equal dimensions. The AE values of the examined crystal were found to be higher than those of the compared crystals across the whole X-ray tube-voltage range. Regarding the EAE, LaBr3:Ce demonstrated a comparatively better performance than the LaCl3:Ce crystal. The emitted-light spectrum of LaBr3:Ce was found to be compatible with various types of photocathodes and silicon photomultipliers. Moreover, the LaBr3:Ce crystal exhibited excellent performance concerning its DQE(0). Considering these properties, the LaBr3:Ce crystal could be considered as a radiation-detector option for hybrid medical-imaging modalities, such as PET/CT and SPECT/CT.

The aim of this work is to investigate, in a wide range of gamma-ray energies, the validity of the "Virtual Point Detector" (VPD) approach to evaluate Full-Energy-Peak Efficiency (FEPE) values for a Cerium-doped Lanthanum Bromide scintillator (LaBr 3 :Ce). With VPD approximation, the detector is assumed equivalent to a virtual point inside the crystal where all the interactions can be considered to occur. The distance of VPD from detector cap is evaluated through experimental point source measurements. The knowledge of the trend of VPD depth as a function of gamma radiation energy allows the evaluation of FEPE values starting from an experimental reference value. The validation of the procedure has been performed by applying the VPD approach to measurement geometries already characterized such as a disk source, an Havar foil irradiated inside a target of a medical cyclotron, and a parallelepided sample geometry, an atmospheric particulate paper filter reduced to 6 cm × 6 cm × 0.7 cm dimensions. FEPE values determined by VPD approach lead to radionuclide activities very close to the ones already obtained with measurements carried out with other detectors. • Validity of Virtual Point Detector approach for a LaBr 3 :Ce scintillator. • Efficiency evaluation for a LaBr 3 :Ce scintillator through a VPD approximation. • Experimental validation of VPD approach also for disk and volume sources. • Knowledge of the detector size and composition is not necessary. [ABSTRACT FROM AUTHOR]

Performance of 1″ × 1″ LaBr3 (5% Ce) scintillator coupled to Hamamatsu R2083 PM Tube has been investigated for the first time. Energy response and timing characteristics of the present assembly have been studied at different operating conditions for its application in fast timing spectroscopy. An energy resolution of 3.38 ± 0.03% at 662 keV γ-energy was obtained in the present work at a bias voltage of − 2800 V and a linear response could be observed up to a bias voltage of − 2500 V. Time resolution of a single LaBr3:Ce crystal was found to be 174 ± 2 ps and 121 ± 3 ps for 511–511 and 1173–1332 cascades respectively. Effect of applied bias voltage on the time resolution of the set up was studied and a steady improvement with increasing bias voltage was observed. Present results were compared with the previous results obtained with similar fast PM tubes and importance as well as implications of the present measurement were also discussed. [ABSTRACT FROM AUTHOR]

Abstract In this work we will present the characterization, in terms of gamma response and internal activity of newly developed crystals that contains Lanthanum in their chemical formula. In particular we tested two LaBr 3 :Ce,Sr, one CLLBC and two CLLB crystals with different volumes. These crystals just overcome the prototype stage and, even if the production in still not standardized at least for large optics, they have been very recently commercialized in sizes interesting for high-energy gamma-ray spectroscopy, as for application in nuclear physics experiments. In particular, we will report on the study of the decay time, light yield and energy resolution with gamma rays, on the response as a function of the gamma interaction point and on the internal activity due to the presence of Lanthanum. [ABSTRACT FROM AUTHOR]

Abstract In this work, an experimental comparison of the capabilities of a scintillation detector based on a NaI:Tl and a LaBr 3 :Ce monolithic crystals is presented. The main advantage of LaBr 3 :Ce respect to NaI:Tl is its very high light yield (i.e. 63photons/keV versus 38photons/keV), allowing a considerable improvement of the statistical factor affecting light collection and, consequently, Spatial Resolution (SR) and Energy Resolution (ER). Nevertheless, the following results show that the improvement of the SR with the LaBr 3 :Ce is smaller than expected. As analyzed, it could be due to the LaBr 3 :Ce refractive index higher than the NaI:Tl one, that leads to a loss of scintillation light. In fact, the measurements produce similar imaging results (SR at crystal center is about 1.1mm for both crystals), while the ER is slightly better for the LaBr 3 :Ce, as expected (7.6% and 8.8% for LaBr 3 :Ce and NaI:Tl, respectively). This work encourages a further and more specific analysis about how the refractive index affects the amount and the shape of crystal light distribution. [ABSTRACT FROM AUTHOR]

We have performed the first experimental campaign using large-volume LaBr 3 :Ce and CeBr 3 detectors from several of the Extreme Light Infrastructure-Nuclear physics (ELI-NP) instrumental setups together with detectors and infrastructure from the ROSPHERE array at the 9 MV Tandem facility at the Horia Hulubei National Institute for Physics and Nuclear Engineering (IFIN-HH). The performance of the detectors and the digital data acquisition system is shown to give a good energy resolution at high energies, and an excellent time resolution. We, furthermore, present the possibilities to integrate the detector system and the digital electronics with various ancillary detectors for, for example, charged particles. [ABSTRACT FROM AUTHOR]

This work aims to investigate the response function and photon interaction of the LaBr 3 :Ce and BGO scintillation detectors using the FLUKA Monte Carlo simulation software. To improve the realism of detectors, the DETGEB card was used to activate the gaussian energy broadening (GEB) function. The GEB parameters of both detectors were obtained by fitting a nonlinear curve to the relation between FWHM and gamma-ray energy. The energy resolution (R), peak-to-Compton ratio (PCR), peak-to-total ratio (PTR), and full-energy peak efficiency (FEPE) of both detectors were investigated by simulation and experiment at different gamma-ray energy obtained from 133Ba, 137Cs, and 60Co sources. The simulated spectra of those radioisotopes were found to agree with the actual spectra. The results found that the R , PCR , and FEPE values of the LaBr 3 :Ce and BGO detectors tend to decrease as energy increases. Moreover, the total atomic cross-section (σ t , a), effective atomic number (Z eff) and effective electron density (N eff) of both crystals was investigated by FLUKA and compared with the XCOM theoretical program covering an energy range of 15 keV to 15 MeV. The simulated results of the σ t , a , Z eff , and N eff are in excellent agreement with the theoretical ones. The GEB parameters obtained from this study will improve the simulation performance of LaBr 3 :Ce and BGO detectors in investigating the gamma-ray response and shielding properties of materials. [ABSTRACT FROM AUTHOR]

Both of the LaBr3:Ce and NaI(Tl) detectors are inorganic scintillators that due to their high light output rate in comparison with organic scintillators and almost other inorganic scintillators are significant. In this research, experimental data for identical measurement of the sealed button sources with both detectors in the presence and absence of the shield were compared with the simulation data by using MCNP 4C code for the crystals of detectors. The obtained results from the radioactive sealed button sources measurements represented that for low energy gamma rays there are noticeable differences between the experimental and simulation data and that is highly due to non-negligible and effective attenuation of these low energy gamma rays in passing through the window and the shield of detectors included the crystals. The high energy gamma rays simulation data are, however, in agreement with the experimental observations. Also, all the simulation data as well as the experimental measurents showed that the efficiency of the LaBr3:Ce detector is higher than that of the NaI(Tl) detector. The simulation results for the shielded button sources are also in agreement with the experimental data in most ranges of gama energies.

In the present study, the response of the crystalline scintillator LaBr3:Ce when excited with X-rays at tube voltages from 50 kVp to 150 kVp was investigated, for possible use in hybrid medical-imaging systems. A single crystal (10 × 10 × 10 mm3) was irradiated by X-rays within the aforementioned tube-voltage range, and the absolute efficiency (AE), as well as the detective quantum efficiency for zero spatial-frequency (DQE(0)), were measured. The energy-absorption efficiency (EAE), the quantum-detection efficiency (QDE) and the spectral compatibility with various optical photodetectors were also calculated. The results were compared with the published data for the LaCl3:Ce, Bi4Ge3O12 (BGO), Lu2SiO5:Ce (LSO), and CdWO4 single crystals of equal dimensions. The AE values of the examined crystal were found to be higher than those of the compared crystals across the whole X-ray tube-voltage range. Regarding the EAE, LaBr3:Ce demonstrated a comparatively better performance than the LaCl3:Ce crystal. The emitted-light spectrum of LaBr3:Ce was found to be compatible with various types of photocathodes and silicon photomultipliers. Moreover, the LaBr3:Ce crystal exhibited excellent performance concerning its DQE(0). Considering these properties, the LaBr3:Ce crystal could be considered as a radiation-detector option for hybrid medical-imaging modalities, such as PET/CT and SPECT/CT. [ABSTRACT FROM AUTHOR]

Abstract: The design of a fast-timing γ-ray detection array aimed at measuring sub-nanosecond half-lives using LaBr3:Ce scintillation crystals is presented. This array will complement novel and existing charged particle and neutron detector arrays at the low-energy branch of a fragment separator (Super-FRS) to be built within the NuSTAR collaboration as part of the future Facility for Anti-proton and Ion Research (FAIR). The array will be used in conjunction with the Advanced Implantation Detector Array (AIDA), to measure implant-decay correlations. Monte-Carlo simulations have been performed to determine the design of the proposed fast-timing array around a localised implantation point. In particular, simulations were used to determine the full-energy peak efficiencies for single cylindrical, conical and ‘hybrid’ detector geometries, as well as complete array configurations of ‘hybrid’ and ∅1.5in.×2in. cylindrical crystals. Timing precision calculations were then used to determine the timing response for each configuration based on its simulated efficiency. An informed decision based on the simulated efficiencies and timing precision calculations allowed the optimum configuration for the array to be determined. [Copyright &y& Elsevier]

Experimental studies of LaBr3 doped with 5%, 10%, 20% and 30% Ce^3+ and CeBr3 are performed for application in TOF-PET. X-ray excited emission spectra, decay time constants, photoelectron yields and energy resolutions are measured from 100 K to 600 K. The results show a strong temperature and Ce^3+ concentration dependence, which is mostly explained by Ce^3+ self-absorption. We modeled how self-absorption affects the scintillation pulse shape and what the consequences are for the detector timing resolution. It shows that self-absorption elongates the decay time constant, whilst it does not affect the scintillation rise time. [ABSTRACT FROM PUBLISHER]

Abstract: Sr2+ co-doped LaBr3:5%Ce scintillators show a record low energy resolution of 2% at 662keV and a considerably better proportional response compared to standard LaBr3:5%Ce. This paper reports on the optical properties and time response of Sr co-doped LaBr3:5%Ce. Multiple excitation and emission bands were observed in X-ray and optically excited luminescence measurements. Those bands are ascribed to three different Ce3+ sites. The first is the unperturbed site with the same luminescence properties as those of standard LaBr3:Ce. The other two are perturbed sites with red-shifted 4f-5d1 Ce3+ excitation and emission bands, longer Ce3+ decay times, and smaller Stokes shifts. The lowering of the lowest 5d level of Ce3+ was ascribed to larger crystal field interactions at the perturbed sites. Two types of point defects in the LaBr3 matrix were proposed to explain the observed results. No Ce4+ ions were detected in Sr co-doped LaBr3:5%Ce by diffuse reflectance measurements. [Copyright &y& Elsevier]

Here we present the ELI Gamma Above Neutron Threshold setup recently implemented at the Extreme Light Infrastructure – Nuclear Physics. The main goals of the detector array are presented, as well as the mechanical design and the performance of the individual detectors. In addition, we have performed Geant4 simulations for realistic beam conditions. Finally, we show the performance of the array as a whole and outline the analysis procedure for complex experimental measurements by reproducing the angular correlations of neutrons following spontaneous fission of a 252Cf source. [ABSTRACT FROM AUTHOR]

The properties of large volume cylindrical 3.5″×8″ (89mm×203mm) LaBr3:Ce scintillation detectors coupled to the Hamamatsu R10233-100SEL photo-multiplier tube were investigated. These crystals are among the largest ones ever produced and still need to be fully characterized to determine how these detectors can be utilized and in which applications. We tested the detectors using monochromatic γ–ray sources and in-beam reactions producing γ rays up to 22.6MeV; we acquired PMT signal pulses and calculated detector energy resolution and response linearity as a function of γ-ray energy. Two different voltage dividers were coupled to the Hamamatsu R10233-100SEL PMT: the Hamamatsu E1198-26, based on straightforward resistive network design, and the “LABRVD”, specifically designed for our large volume LaBr3:Ce scintillation detectors, which also includes active semiconductor devices. Because of the extremely high light yield of LaBr3:Ce crystals we observed that, depending on the choice of PMT, voltage divider and applied voltage, some significant deviation from the ideally proportional response of the detector and some pulse shape deformation appear. In addition, crystal non-homogeneities and PMT gain drifts affect the (measured) energy resolution especially in case of high-energy γ rays. We also measured the time resolution of detectors with different sizes (from 1″×1″ up to 3.5″×8″), correlating the results with both the intrinsic properties of PMTs and GEANT simulations of the scintillation light collection process. The detector absolute full energy efficiency was measured and simulated up to γ-rays of 30MeV [ABSTRACT FROM AUTHOR]

Abstract: We studied the performances of the LaBr3:Ce scintillator when optically coupled to NaI:Tl and CsI:Na in a Phoswich detector for the R&D phase of the gamma ray calorimeter PARIS (Photon Array for the studies with Radioactive Ion and Stable beams). This detector has the purpose to measure γ-energies in a wide range (100keV–40MeV), and it will be used principally as a part of the SPIRAL2 instrumentation at GANIL. In this communication we report on the study of the light yield and energy resolution for gamma detection realized by coupling the phoswiches with various photomultiplier tubes, providing different characteristics. We were interested in investigating the possible degradation of the scintillation light produced by the LaBr3:Ce due to the presence of NaI:Tl/CsI:Na crystals, before being detected on the photocathode. For this purpose we realized all the measurements employing a standard ADC and QDC read-out system leading the possibility to perform a gate-based event selection. In this study we measured an energy resolution of 4.6% with an uncollimated 137Cs source for a 50.8×50.8×50.8mm3 LaBr3:Ce coupled to a 50.8×50.8×152.4mm3 NaI:Tl. This value is 30% bigger than the energy resolution measured for a 50.8×50.8×101.6mm3 stand-alone LaBr3:Ce but still in the specifications for the PARIS collaboration physics list. [Copyright &y& Elsevier]

Abstract: The performances of Ce-activated Lu3Al5O12 (LuAG:Ce), Lu2SiO5 (LSO:Ce) and LaBr3 (LaBr3:Ce) scintillator crystals were investigated for γ-ray detection. The light yield and energy resolution were measured using photomultiplier tube (XP5500B PMT) readout. For 662 keV (137Cs source), an energy resolution of 3.5% obtained for LaBr3:Ce is much better than that of 6.7% and 8.3%, respectively, for LuAG:Ce and LSO:Ce. The light yield nonproportionality and energy resolution versus energy of γ-rays were measured and the intrinsic resolution of the crystals was determined. The LaBr3:Ce exhibits a good proportionality within 7% deviation from unity at 16.6 keV, which is much better than that of 22% and 45%, respectively, for LuAG:Ce and LSO:Ce. The photofraction was determined at 320, 662 and 835 keV for studied crystals and compared with the ratio of the cross-sections for the photoelectric effect to the total one calculated using WinXCom program. [Copyright &y& Elsevier]

We have developed a LaBr3 :Ce scintillator array consisting of 8 x 8 pixels with a size of 5.8 mm x 5.8 mm x 15.0 mm, which serves as an absorber of scattered gamma rays with ener- gies from 0.1 to 1 MeV in a Compton camera. The pixels were cut from two pieces of LaBr3 :Ce crystal with a diameter of 38mm and a length of 38 mm with full width at half-maximum (FWHM) energy resolutions of 4.1±0.1% and 3.0±0.1% at 356 and 662 keV, respectively, measured with a single anode photomultiplier tube (PMT). The crystal had the following volumetric uniformities: light outputs with a difference of 0.5% (standard deviation: SD) and energy resolutions with that of 2% (SD) at 356 keV. In contrast, for each pixel in the array, the average and SD FWHM energy resolutions over 64 pixels, measured with a single-anode PMT and a collimator, were 5.8 ± 0.9% at 356 keV. The array was then coupled to a 64-channel multi-anode PMT (Hamamatsu H8500), the anode pitch of which was the same as the LaBr3 :Ce pixel pitch of 6.1 mm. When the 64 anodes were read out from four channels in a resistor chain by the charge division method, the FWHM energy resolution of all 64 pixels was 7.0 ± 0.5% at 662 keV, whereas that of the inner 6 x 6 pixels was 5.8±0.4% at 662 keV. In addition, we measured a Gd2 SiO5 :Ce (GSO:Ce) scintillator array consisting of 8 x 8 pixels with a size of 5.9mm x 5.9mm x 13.0mm to compare its performance with that of the LaBr3 :Ce array. The FWHM energy resolution of all 64 GSO:Ce pixels was 10.8 ± 0.3% at 662 keV. With these energy resolutions, FWHM angular resolutions of the Compton camera using the LaBr3 :Ce and GSO:Ce arrays are expected to be 4.6° and 5.3°, respectively, at 662 keV. [ABSTRACT FROM AUTHOR]

Abstract: The scintillator material LaBr3:Ce, which was discovered in 2001, has grown in popularity for a variety of applications in homeland security and nuclear medicine. In this paper we investigate its use for nuclear science spectroscopy applications in the context of in-beam gamma-ray spectroscopy with fast ion beams. In such experiments, the Doppler broadening of the gamma-ray line measured with a finite-size detector in the laboratory fundamentally limits the achievable energy resolution. For a typical experiment this effect is of the order of 3%. With the intrinsic energy resolution of LaBr3:Ce better than 3% FWHM at 662keV, and its favorable stopping power, it could be a nearly ideal scintillator for gamma-ray spectroscopy applications with fast beams. Results from in-beam gamma-ray spectroscopy measurements using two LaBr3:Ce scintillators are presented and compared to results from segmented germanium detectors. Results from these measurements suggest that LaBr3:Ce based scintillation arrays can provide a viable tool for many experiments. Additionally, we show that the excellent timing properties of LaBr3:Ce can significantly reduce background events in the gamma-ray spectra. [Copyright &y& Elsevier]

Abstract: The absolute total and absolute peak detection efficiencies of gamma ray detector materials NaI:Tl, CdZnTe, HPGe, HPXe, LaBr3:Ce and LaCl3:Ce were simulated and compared to that of polyvinyltoluene (PVT). The dimensions of the PVT detector were 188.82cm×60.96cm×5.08cm, which is a typical size for a single-panel portal monitor. The absolute total and peak detection efficiencies for these detector materials for the point, line and spherical source geometries of 60Co (1332keV), 137Cs (662keV) and 241Am (59.5keV) were simulated at various source-to-detector distances using the Monte Carlo N-Particle software (MCNP5-V1.30). The comparison of the absolute total detection efficiencies for a point, line and spherical source geometry of 60Co and 137Cs at different source-to-detector distance showed that the absolute detection efficiency for PVT is higher relative to the other detectors of typical dimensions for that material. However, the absolute peak detection efficiency of some of these detectors are higher relative to PVT, for example the absolute peak detection efficiency of NaI:Tl (7.62cm diameter×7.62cm long), HPGe (7.62cm diameter×7.62cm long), HPXe (11.43cm diameter×60.96cm long), and LaCl3:Ce (5.08cm diameter×5.08cm long) are all greater than that of a 188.82cm×60.96cm×5.08cm PVT detector for 60Co and 137Cs for all geometries studied. The absolute total and absolute peak detection efficiencies of a right circular cylinder of NaI:Tl with various diameters and thicknesses were determined for a point source. The effect of changing the solid angle on the NaI:Tl detectors showed that with increasing solid angle and detector thickness, the absolute efficiency increases. This work establishes a common basis for differentiating detector materials for passive portal monitoring of gamma ray radiation. [Copyright &y& Elsevier]

Abstract: Cerium-doped lanthanum bromide, LaBr3(Ce), scintillator possesses several outstanding properties that make it an attractive choice for security, medical, and geophysical radiation detection applications. Among these properties are good density (5.1g/cc), excellent energy resolution (∼3% full-width at half-maximum (FWHM) at E γ=662keV), brightness (>65,000photon/MeV), and speed, (τd <20ns). Unfortunately, the development of many prospective devices using this scintillator has been hampered by the lack of large crystals (>100cc). The anisotropic thermal expansion exhibited by this material makes it difficult to grow large ingots due to the build up of internal stresses as it cools, causing fracturing. Recently, Saint–Gobain Crystals has achieved successful growths of large unfractured ingots, from which large detectors have been assembled (>150cc). The outstanding properties seen in small pieces are retained up to at least 155cc (the largest assembled into a single detector thus far). A cylindrical LaBr3(Ce=5%) crystal with dimensions of diameter=51mm, and length=76mm achieves energy resolution of 3.1% FWHM at 662keV, and brightness of 165% of NaI with good uniformity throughout the crystal. Scintillation light yield and energy resolution have been examined as a function of crystal size and γ-ray energy. Spatial mapping of a large crystal was examined and shown to be uniform. Large crystals enable accurate measurements of the intrinsic γ-ray background from 138La (0.09% nat. abun., γ-ray emission at 1436 and 789keV). This background is shown to scale appropriately in size with theoretical calculations. [Copyright &y& Elsevier]

The effect of high dose 60Co gamma irradiation on photoelectron yield, energy resolution, optical transmission, scintillation time profiles and thermoluminescence glow curves of LaBr3:5%Ce and LaCl3:10%Ce crystals has been investigated. Both materials show lower yields and deteriorated resolutions after exposure to a strong 60Co source, however their transmission, yield proportionality, scintillation decay, and thermoluminescence remain unaffected. Initial scintillation characteristics can be retrieved neither by spontaneous recovery nor upon heating in vacuum. [ABSTRACT FROM AUTHOR]

Abstract: The principal limiting factor in the clinical acceptance of scintimammography is certainly its low sensitivity for cancers sized <1cm, mainly due to the lack of equipment specifically designed for breast imaging. The National Institute of Nuclear Physics (INFN) has been developing a new scintillation camera based on Lanthanum tri-Bromide Cerium-doped crystal (LaBr3:Ce), that demonstrating superior imaging performances with respect to the dedicated scintillation γ-camera that was previously developed. The proposed detector consists of continuous LaBr3:Ce scintillator crystal coupled to a Hamamatsu H8500 Flat Panel PMT. One centimeter thick crystal has been chosen to increase crystal detection efficiency. In this paper, we propose a comparison and evaluation between lanthanum γ-camera and a Multi PSPMT camera, NaI(Tl) discrete pixel based, previously developed under “IMI” Italian project for technological transfer of INFN. A phantom study has been developed to test both the cameras before introducing them in clinical trials. High resolution scans produced by LaBr3:Ce camera showed higher tumor contrast with a detailed imaging of uptake area than pixellated NaI(Tl) dedicated camera. Furthermore, with the lanthanum camera, the Signal-to-Noise Ratio (SNR) value was increased for a lesion as small as 5mm, with a consequent strong improvement in detectability. [Copyright &y& Elsevier]

Abstract: The availability of LaBr3:Ce crystals from St. Gobain has started various investigations in the field of medical imaging, in particular in PET, SPECT and Compton camera systems. At present LaBr3:Ce crystals are available in a continuous shape covering up to 10×10cm2 with a thickness of 1cm, in contrast, serious concerns are arising in pixellated manufacturing. With the aim of verifying the potentials introduced by LaBr3:Ce for SPET imaging, two small γ cameras based on Anger camera principle have been assembled and imaging performances were compared. Two crystals of LaBr3:Ce and NaI(Tl) with the same detection area (5×5cm2) and thickness of 5 and 1.5mm, respectively were been integrally assembled with a H8500 Hamamatsu flat panel PMT. Through the thicker crystal, the LaBr3:Ce camera showed superior imaging and detection performances at 140keV compared with the NaI(Tl) one, with 0.9mm FWHM intrinsic spatial resolution, 8% FWHM energy resolution and 80% intrinsic detection efficiency. [Copyright &y& Elsevier]

Abstract: Over the last 3 years, there has been a growing interest in the development of a new class of fast scintillators such as LaCl3:Ce and LaBr3:Ce. Their superior energy resolution is opening an easier way to improve spatial resolution. In this paper we present the results obtained from the first LaBr3:Ce small gamma camera. It is based on continuous 50×50mm2 crystal, 5mm thick, integral assembled with a Hamamatsu Flat panel PMT. This detector configuration permits the narrowest light distribution with the highest light output in order to obtain the best spatial and energy resolution values, respectively. At the same time, 5mm crystal thickness carries out 80% efficiency at 140keV photon energy. Measurements of spatial resolution are also compared with the analogous ones obtained from another 50×50mm2 LaBr3:Ce crystal, assembled with a 3mm glass optical window. Energy resolution values have been furtherly compared with ones obtained from a LaBr3:Ce 1in. diameter and thickness optimized for spectrometric measurements. The first LaBr3:Ce gamma camera shows excellent intrinsic spatial resolution values such as 0.9mm, with a best energy resolution value of 6.5% at 140keV photon energy. [Copyright &y& Elsevier]

Measurements have been performed with scintillation crystals of LaBr 3 :Ce coupled to an array of Silicon Photomultipliers (SiPMs) in a 3 T magnetic field. The SiPMs were read out by digital data acquisition systems, including the GET electronics system. Inside of the B-field, energy resolution values of 3.82% FWHM at 661.7 keV are reported for a 1.5$\protect \relax \special {t4ht=′}\protect \relax \special {t4ht=′}$ cubic LaBr 3 :Ce crystal coupled to a 6 × 6 array of 6 × 6 mm2 SiPMs. No measurable degradation in energy resolution due to the presence of the strong magnetic field was observed. [ABSTRACT FROM AUTHOR]

Abstract: In this work, we report and compare the results of γ-ray spectroscopy measurements performed using a LaBr3:Ce crystal coupled to a photomultiplier tube with modified base and to a Si-avalanche photodiode readout by standard electronics. Energy resolution values have been obtained in the range from 59.5keV (241Am) to 1332keV (60Co). Good linearity in energy response has been found. Energy resolution values obtained with avalanche photodiode readout are underestimated due to the small active area of the presently available photosensor with respect to crystal dimension. [Copyright &y& Elsevier]