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The scintillation characteristics of Lu0.8Gd2.2 (Al5– x Ga x )O12:Ce,Mg ( $x = 2.6$ and 3) single crystals grown by the micropulling down method are investigated. The light yield of 27600 photons/MeV obtained for Lu0.8Gd2.2Al2Ga3O12:Ce,Mg is higher than that of 25 400 photons/MeV obtained for Lu0.8Gd2.2Al2.4Ga2.6O12:Ce,Mg. The photoluminescence and scintillation decays measured at room temperature (RT) for Lu0.8Gd2.2Al2Ga3O12:Ce,Mg are faster than those for Lu0.8Gd2.2Al2.4Ga2.6O12:Ce,Mg. Temperature dependence of radioluminescence (RL) intensity indicates a lower quenching temperature for Lu0.8Gd2.2Al2Ga3O12:Ce,Mg. Coincidence time resolution of a Lu0.8Gd2.2Al2Ga3O12:Ce,Mg detector in coincidence experiment with a BaF2 detector was measured to be 410 ps. The afterglow and thermally stimulated luminescence (TSL) characteristics below RT are also measured.

Scintillation characteristics of Y0.8Gd2.2 (Al5– x Ga x )O12:Ce,Mg ( $x = 2.6$ and 3) single crystals are presented. At 662-keV $\gamma $ -rays, the light yield of 35 600 photons/MeV obtained for Y0.8Gd2.2Al2Ga3O12:Ce,Mg is higher than that of 32 600 photons/MeV for Y0.8Gd2.2Al2.4Ga2.6O12:Ce,Mg. Scintillation decay components of 32.3 ns (52.4%) + 104 ns (47.6%) obtained for Y0.8Gd2.2Al2Ga3O12:Ce,Mg are faster than those of 11.5 ns (5%) + 51.2 ns (69%) + 302 ns (26%) obtained for Y0.8Gd2.2Al2.4Ga2.6O12:Ce,Mg. The coincidence time resolution of 336 and 389 ps was obtained, respectively, for Y0.8Gd2.2Al2Ga3O12:Ce,Mg-photomultiplier (PMT) and Y0.8Gd2.2Al2.4Ga2.6O12:Ce,Mg-PMT, in coincidence experiment with a BaF2-PMT detector. The radioluminescence yield at room temperature (RT) is comparable for both crystals while the yield below 130 K is about 20% higher for Y0.8Gd2.2Al2Ga3O12:Ce,Mg. Afterglow and thermally stimulated luminescence (TSL) below RT are also measured.

The scintillation properties of Mg2+-codoped Lu0.6Gd2.4Al2Ga3O12:Ce (LGAGG:Ce,Mg) single crystal grown by Czochralski’s method are investigated. The light yield (LY), scintillation decay time, and coincidence time resolution are presented in comparison with a GAGG:Ce,Mg reference crystal. The LY of 26 200 photons/MeV obtained for LGAGG:Ce,Mg is lower than that of 39 600 photons/MeV for GAGG:Ce,Mg. Despite a lower LY value, the time resolution of LGAGG:Ce,Mg is comparable to that of GAGG:Ce,Mg due to its faster scintillation decay time. LGAGG:Ce,Mg exhibits a much faster afterglow decay and a lower thermally stimulated luminescence intensity with respect to GAGG:Ce,Mg.

[EN] Posidonia oceanica meadows are ecosystem engineers that play several roles in marine environment maintenance. In this sense, monitoring of the spatial distribution and health status of their meadows is key to make decisions about protecting them against their degradation. With the aim of checking the ability of a simple low-cost acoustic method to acquire information about the state of P. oceanica meadows as ecosystem indicators, ground-truthing and acoustic data were acquired over several of these meadows on the Levantine coast of Spain. A 200 kHz side scan sonar in a vertical configuration was used to automatically estimate shoot density, canopy height and cover of the meadows. The wide athwartship angle of the transducer together with its low cost and user friendliness entail the main advantages of this system and configuration: both improved beam path and detection invariance against boat rolling. The results show that canopy height can be measured acoustically. Furthermore, the accumulated intensity of the echoes from P. oceanica in the first 30 centimeters above the bottom is indirectly related to shoot density and cover, showing a relation that should be studied deeply., Funding for open access charge: Universitat Politècnica de València

Underwater noise has been identified as a relevant pollution affecting marine ecosystems in different ways. Despite the numerous studies performed over the last few decades regarding the adverse effect of underwater noise on marine life, a lack of knowledge and methodological procedures still exists, and results are often tentative or qualitative. A monitoring methodology for the behavioral response of bluefin tuna (Thunnus thynnus) when exposed to ship and wind turbine operational noises was implemented and tested in a fixed commercial tuna feeding cage in the Mediterranean sea. Fish behavior was continuously monitored, combining synchronized echosounder and video recording systems. Automatic information extracted from acoustical echograms was used to describe tuna reaction to noise in terms of average depth and vertical dimensions of the school and the indicators of swimming speed and tilt direction. Video recordings allowed us to detect changes in swimming patterns. Different kinds of stimuli were considered during bluefin tuna cage monitoring, such as noise generated by feeding boats, wind farm operational noise, and other synthetic signals projected in the medium using a broadband underwater projector. The monitoring system design was revealed as a successful methodological approach to record and quantify reactions to noise. The obtained results suggested that the observed reactions presented a strong relationship with insonification pressure level and time. Behavioral changes associated with noise are difficult to observe, especially in semi-free conditions; thus, the presented approach offered the opportunity to link anthropogenic activity with possible effects on a given marine species, suggesting the possibility of achieving a more realistic framework to assess the impacts of underwater noise on marine animals., AZIMUT IEO, SI

Praseodymium activated lutetium aluminum garnet (LuAG:Pr) is an inorganic scintillator belonging to the garnet family of crystals. It is characterized by an emission related to the radiative and allowed 5 d 1 4 f 1 → 4 f 2 transition in trivalent praseodymium ions. It has been shown that it has good scintillation qualities such as light output, energy resolution and fast decay times. There have been attempts to enhance the already good properties of LuAG:Pr such as optimizing annealing conditions, since this material has a potential to be used in Positron Emission Tomography (PET) detector systems. Previously reported studies show that there have been successful cases of improving the light yield and energy resolution. In this paper we show a detailed study of the non-proportionality and energy resolution in LuAG:Pr crystals that have been modified by partially substituting lutetium with yttrium and introducing intentional trace amounts of molybdenum co-doping. The measurements have been performed with varied shaping times to study the influence of long decay components on the scintillation parameters.

The scintillation characteristics of Gd3Al2Ga3O12:Ce, Li (GAGG:Ce,Li) and Gd3Al2Ga3O12:Ce, Mg (GAGG:Ce,Mg) single crystals were compared. Radioluminescence spectra and photoluminescence decay curves were measured at various temperatures between 77 and 500 K to investigate the thermal luminescence quenching. At 662 keV γ rays, the LY value of 35,400 photons/MeV and energy resolution of 6.9% obtained for GAGG:Ce, Li are superior to those of 24,200 photons/MeV and 9.5% for GAGG:Ce,Mg. Scintillation decays are approximated by a double exponentials with a fast principal decay component of 47 ns (83%) for GAGG:Ce, Mg and 90 ns (86%) for GAGG:Ce,Li. Coincidence time resolution of 282 ps obtained for GAGG:Ce, Mg is better than that of 389 ps for GAGG:Ce,Li. GAGG:Ce, Mg shows a much lower afterglow and thermally stimulated luminescence intensity with respect to GAGG:Ce,Li.

In the first part of this paper the various characteristics of SiPMs that affect the use of SiPMs in gamma spectroscopy using scintillators , are reviewed. It covers SiPM gain, photon detection efficiency (PDE), after-pulses and cross-talk (which are responsible for the excess noise factor), dark noise, and linearity of response. In this respect the influence of the SiPMs’ effective dead time on the linearity of the response is discussed. In the second part, the optimization of SiPM operation for the best energy resolution and linearity of response is presented. Finally, a number of tests on combinations of SiPM arrays of different sizes that are coupled to different scintillators used in gamma spectroscopy are reported (such as NaI(Tl), BGO, LaBr 3 , and LYSO are reviewed, including 3x3 inch NaI(Tl) and BGO tests. Besides the characterization of the different SiPMs used in scintillation detection and spectroscopy, a discussion is carried out concerning their present and future application in various fields of use — covering instrumentation for homeland security, environmental study, plasma physics and others.

A custom design cryostat was constructed to study the temperature dependence of relative light yield and non-proportionality trends of scintillators between −182 °C and ＋152 °C. CsI:Tl crystal response to γ -rays and X-rays was investigated between 14 keV and 662 keV. Scintillation light was detected by a SiPM device, which was installed on a copper frame separated from the crystal and the cooling rod to enable operating the device at room temperature. The scintillation efficiency of CsI:Tl is peaked at about room temperature. The light yield of CsI:Tl at temperature close to liquid nitrogen boiling point is reduced by a factor of 15 in comparison to room temperature conditions. The non-proportionality of CsI:Tl scintillation response is high at low temperatures and is getting more proportional with increasing temperature.

In this work we present a comparison between the two liquid scintillators BC-501A and BC-537 in terms of their performance regarding the pulse-shape discrimination between neutrons and γ rays. Special emphasis is put on the application of artificial neural networks . The results show a systematically higher γ -ray rejection ratio for BC-501A compared to BC-537 applying the commonly used charge comparison method. Using the artificial neural network approach the discrimination quality was improved to more than 95% rejection efficiency of γ rays over the energy range 150 to 1000 keV for both BC-501A and BC-537. However, due to the larger light output of BC-501A compared to BC-537, neutrons could be identified in BC-501A using artificial neural networks down to a recoil proton energy of 800 keV compared to a recoil deuteron energy of 1200 keV for BC-537. We conclude that using artificial neural networks it is possible to obtain the same γ -ray rejection quality from both BC-501A and BC-537 for neutrons above a low-energy threshold. This threshold is, however, lower for BC-501A, which is important for nuclear structure spectroscopy experiments of rare reaction channels where low-energy interactions dominates.

The light response of cesium iodide crystals was measured at temperatures of 303 K (30 °C) to 203 K ( − 70 °C) and for gamma sources with energies from 17 keV to 835 keV. Two different methods were used to determine the properties of the CsI:Tl crystals. The first used classic analogue spectrometry equipment to check the dependence of energy resolution, intrinsic resolution, and non-proportionality parameters as a variations in temperature, excitation energy, and integration time. The second method registered the light pulses from the PMT without integrating or shaping circuits. At the current stage of the research, the authors have decided to maintain the thesis about the existence of three decay components in CsI:Tl crystals that was employed in previous studies - the light pulse decays were analyzed under this assumption. We observed that the light pulses slowed with a decrease in temperature. When the crystals were cooled from 303 K to 203 K, the fitted decay times increased significantly by factors of two to four. The non-proportionality of the three fitted components was also determined and it was found that the first and second (fast and slow components) exhibited positive non-proportionality while the third (tail component) presented a negative trend for non-proportionality at temperatures of 303 K–203 K. It was found that using sufficiently long integration times, to include compensating trends of all decay components, the light response of CsI:Tl could be proportional.

Neutron inspection of sea-going cargo containers has been widely studied in the past 20 yr to non-intrusively detect terrorist threats, like explosives or Special Nuclear Materials (SNM), and illicit goods, like narcotics or smuggling materials. Fast 14 MeV neutrons are produced by a portable generator with the t(d, n)α fusion reaction, and tagged in both direction and time thanks to the alpha particle detection. This Associated Particle Technique (APT) allows focusing inspection on specific areas of interest in the containers, previously identified as containing suspicious items with X-ray radiographic scanners or radiation portal monitors. We describe the principle of APT for non-nuclear material identification, and for nuclear material detection, then we provide illustrations of the performances for 10 min inspections with significant quantities (kilograms) of explosives, illicit drugs, or SNM, in different cargo cover loads (e.g. metallic, organic, or ceramic matrices).

This paper presents the results of the fast neutron irradiation (E$_n$ > 0.5MeV) of an EJ-276 scintillator performed in the MARIA research reactor with fluence up to 5.3$\times$10$^{15}$ particles/cm$^2$. In our work, four samples with size $��$25.4~mm$\times$5~mm were tested. The changes in the light yield, emission and absorption spectrum and neutron/gamma discrimination using PuBe source before and after irradiation are presented. The figure of merit in neutron/gamma discrimination based on the charge integration method for different neutron fluences and different short gate integration times are determined., 13 pages, 15 figures

Relative changes of light yield were investigated for LuAG:Pr, LuAG:Pr,Mo and LuYAG:Pr as a function of sample temperature. The measurements were performed using a dedicated cryostat filled with liquid nitrogen allowing for controlling the temperature of the samples between 90 K and 425 K. Scintillation light was detected by an MPPC photodetector, which was installed on a copper frame separated from the crystal and the cooling rod. Light yields as a function of temperature were investigated by irradiation of the crystals with 662 keV gamma-rays from a 137 Cs source. The temperature dependences were recorded using a short ( 1 μ s ) and long ( 10 μ s ) shaping time constants in the spectroscopy amplifier to study the changes in the intensity of fast and slow scintillation components. In addition, the ratio of light yield measured with short and long shaping time was calculated, providing some information on the balance between fast and slow decay modes in the tested scintillators.

This paper presents the results of neutron irradiation of two types of Multi-Pixel Photon Counter (MPPC). The measurements were taken at the National Centre for Nuclear Research (NCBJ), Poland and the Joint Institute for Nuclear Research (JINR), Russia. Two types of neutron source were used: PuBe with a continuous energy spectrum up to 11 MeV, and mono-energetic 4.8 MeV neutrons produced in a (d,d) reaction. For both sources, fluence in the range of 10 10 n/mm 2 was achieved. A series of MPPC tests were performed after each irradiation. The changes in MPPC properties, such as current–voltage (I–V) characteristics, breakdown voltage and energy resolution of 662 keV from the 137Cs gamma line for a Gd3Al2.6Ga2.4O12 :Ce (1%) scintillator as a function of neutron fluence are presented.

Scintillation properties of Czochralski-grown Gd3(Al5-xGax)O12:Ce (x = 2.3, 2.6, 3.0) single crystals were investigated. With increasing Ga content in garnet host, the radioluminescence band due to 5d1 → 4f emission transition was blue-shifted due to a decrease in the crystal field splitting of the 5 d levels. At 662 keV γ rays, the LY value of 47,000, 55,100 and 51,900 ph/MeV was obtained for Gd3Al2.7Ga2.3O12:Ce, Gd3Al2.4Ga2.6O12:Ce and Gd3Al2Ga3O12:Ce, respectively. In spite of a lower LY value, Gd3Al2.7Ga2.3O12:Ce shows good energy resolution of 4.1% due to its proportionality of LY. The ratio of LY values under excitation with α- and γ-rays (α/γ ratio) was also determined. The fast component decay time with relative intensity of 146 ns (66%), 142 ns (76%) and 112 ns (76%) was measured in the scintillation decay of Gd3Al2.7Ga2.3O12:Ce, Gd3Al2.4Ga2.6O12:Ce and Gd3Al2Ga3O12:Ce, respectively. Good coincidence time resolution of Gd3Al2Ga3O12:Ce is due to a high initial photon emission rate.

The paper presents a study of n ∕ γ discrimination with 4x4 ch and 8x8 ch Multi Pixel Photon Counter (MPPC) arrays in neutron detectors based on Stilbene and EJ299-33 plastic scintillators. The n ∕ γ discrimination showed an excellent capability of the MPPC arrays, comparable to that observed earlier with the classical PMTs. Particularly, an application of a zero-crossing method of n − γ discrimination prevented deterioration of the discrimination by the slow response of the Silicon Photomultiplier (SiPM, or MPPC interchangeably) array related to its large capacitance. It was confirmed by a good agreement of the Figure of Merit normalized to the number of photoelectrons determined for the MPPC arrays and XP5500 PMT.

Majority of papers concerning scintillation detectors with light readout by means of silicon photomultipliers refer to nuclear medicine or radiation monitoring devices where energy of detected gamma rays do not exceed 2 MeV. Detection of gamma radiation with higher energies is of interest to e.g. high energy physics and plasma diagnostics . The aim of this paper is to study applicability (usefulness) of SiPM light readout in detection of gamma rays up to 6.1 MeV in combination with various scintillators . The reported measurements were made with 3 samples of one type of Hamamatsu TSV (Through-Silicon Via technology) MPPC arrays. These 4x4 channel arrays have a 50 × 50 μ m2 cell size and 12 × 12 mm2 effective active area. The following scintillators were used: CeBr3 , NaI:Tl, CsI:Tl. During all the tests detectors were located in a climatic chamber. The studies are focused on optimization of the MPPC performance for practical use in detection of high energy gamma rays. The optimization includes selection of the optimum operating voltage in respect to the required energy resolution, dynamic range, linearity and pulse amplitude. The presented temperature tests show breakdown voltage dependence on the temperature change and define requirements for a power supply and gain stabilization method. The energy spectra for energies between 511 keV and 6.1 MeV are also presented and compared with data acquired with a classic photomultiplier XP5212B readout. Such a comparison allowed study of nonlinearity of the tested MPPCs, correction of the energy spectra and proper analysis of the energy resolution.

Optical and scintillation properties of LuGd2Al2Ga3O12:Ce, Lu2GdAl2Ga3O12:Ce, and Lu2YAl2Ga3O12:Ce single crystals are compared. The blue-shift of 5d1 → 4f photoluminescence emission (PL) band is observed upon partial substitution of Gd 3 + with a smaller Lu 3 + (or Y 3 + ) ion. At 662 keV γ -rays, the light yield of 35,400 ± 1,700 ph/MeV obtained for LuGd2Al2Ga3O12:Ce is higher than that of 29,200 ± 1,500 ph/MeV and 20,200 ± 1,000 ph/MeV for Lu2GdAl2Ga3O12:Ce and Lu2YAl2Ga3O12:Ce, respectively. Scintillation decays are approximated by sum of exponentials with the fast component decay time and relative intensity of 78 ns (42%) for LuGd2Al2Ga3O12:Ce, 48 ns (71%) for Lu2GdAl2Ga3O12:Ce and 45 ns (88%) for Lu2YAl2Ga3O12:Ce, which leads to a superior coincidence time resolution of Lu2YAl2Ga3O12:Ce. PL decay time at 110 K and 290 K, afterglow characteristics, and mass attenuation coefficient at 59.5 keV and 662 keV γ - rays are also presented.

The main objective of this work was to characterize the new multi-pixel photon counter (MPPC) arrays with a 12 × 12 mm 2 and a 24 × 24 mm 2 active area, made using through-silicon via (TSV) technology and with trenches introduced between the cells, in gamma-ray spectrometry with five different scintillators: CsI:Tl, NaI:Tl, LSO/LYSO, BGO, and LaBr 3 . The results of the study are compared to those obtained previously with the older sample of the 12 × 12 mm 2 MPPC array made as a monolithic device. TSV MPPC array with the size of 24 × 24 mm 2 is one of the first commercially available SiPM with such a large active area and with the dead space between channels minimized to only 0.2 mm. Moreover, in these devices, Hamamatsu introduced trenches between cells to reduce cross-talk. Hence excess noise factor (ENF) was also reduced from a value of 1.7 to 1.2 in comparison to the “old” monolithic sample (data for the same overvoltage of 1.3V). Whereby for the new MPPCs, the optimum operating voltage is higher by about 0.6V. In consequence, this higher optimal overvoltage means a higher photon detection efficiency (PDE) and number of photoelectrons, and leads to improved energy resolution. Energy resolution measured for the 662keV full energy peak in a 137 Cs γ -source spectrum recorded with 12 × 12 mm 2 TSV MPPC and two CsI:Tl scintillators ( 12 × 12 × 12 mm 3 and 1 × 1 in ) equals to 5.8% and 6.8%, respectively. For the “old” MPPC with the same CsI:Tl scintillators energy resolution is equal to 6.4% and 7.1%, respectively. These improved TSV MPPC arrays can be commercially used for scintillation light readout of “large” crystals with a diameter of 1 × 1 in or 2 × 2 in , suitable for gamma spectrometry in a wide range of applications. The combination of new 8 × 8 ch ( 24 × 24 mm 2 ) TSV MPPC and 2 × 2 in NaI:Tl gives an excellent energy resolution below 8%, despite the incomplete match of the scintillator surface to the active area of MPPC and loss of the part of the light.

LaBr3:Ce,CeBr3 and GAGG:Ce scintillators were investigated and the determined characteristics were compared with those obtained for the well-known and widely used CsI:Tl and NaI:Tl crystals. All the detectors were of the same size of 10 × 10 × 5 mm3. The aim of this test study was to single out scintillation detectors most suitable for γ-ray spectrometry and γ-ray emission radial profile measurements in high-temperature plasma experiments. Decay time, energy resolution, non-proportionality and full energy peak detection efficiency ere measured for γ-ray energies up to 1770 keV. Due to their good energy resolution, short decay time and high detection efficiency for MeV gamma rays, LaBr3:Ce and CeBr3 scintillators are proposed as the best candidates for use especially under conditions of high count rates, which are expected in the forthcoming DT experiments.

The market of Silicon Photomultipliers (SiPMs) consists of many manufacturers that produce their detectors in different technology. Hamamatsu (Japan) and SensL (Ireland) seems to be the most popular companies that produce large SiPM arrays. The aim of this work is characterization and comparison of 4×4 channel SiPM arrays produced by these two producers. Both of the tested SiPMs are made in through-silicon via (TSV) technology, consist of 16, 3×3 mm avalanche photodiode (APD) cells and have fill factor slightly above 60%. The largest difference is a single APD cell size and hence total number of APD cells (55,424 for Hamamatsu, 76,640 for SensL). In the case of SensL SiPM, its spectral response characteristics is shifted slightly toward shorter wavelengths with maximum at 420 nm (450 nm for Hamamatsu). The presented measurements cover selection of the SiPM optimum operating voltage (in respect to energy resolution), verification of the excess noise factor and check of the linearity characteristics. Moreover, the gamma spectrometry with LSO, BGO and CsI:Tl scintillators together with pulse characteristics for these crystals (rise time and fall time) is reported, as well as temperature dependence. The presented measurements show better performance of the SensL array comparing to the Hamamatsu detector.

The optical and scintillation characteristics of Gd 2 YAl 2 Ga 3 O 12 :Ce and Lu 2 YAl 2 Ga 3 O 12 :Ce single crystals are investigated. At 662 keV γ-rays, light yield (LY) of 37,900 ph/MeV and energy resolution of 7.0% obtained for Gd 2 YAl 2 Ga 3 O 12 :Ce are superior to those of 18,900 ph/MeV and 11.5% obtained for Lu 2 YAl 2 Ga 3 O 12 :Ce. Scintillation decays are measured using the time-correlated single photon counting technique. A fast component decay time of 45 ns with relative intensity of 88% obtained for Lu 2 YAl 2 Ga 3 O 12 :Ce is superior to that of 50 ns (65%) for Gd 2 YAl 2 Ga 3 O 12 :Ce. The linear attenuation coefficient at 662 keV γ-rays is also determined and discussed.

The luminescence and scintillation characteristics of cerium-doped lutetium-gadolinium orthosilicate (Lu x Gd 2−x SiO 5 :Ce; x=0, 0.8, 1.8) single crystals were investigated. At 662 keV γ-rays, the light yield of 29,800±3000 ph MeV −1 obtained for Lu 1.8 Gd 0.2 SiO 5 :Ce is higher than that of 20,200±2000 and 11,800±1200 ph MeV −1 obtained for Lu 0.8 Gd 1.2 SiO 5 :Ce and Gd 2 SiO 5 :Ce, respectively. The fast component decay time of 32, 18 and 17 ns was measured in the scintillation decay of Gd 2 SiO 5 :Ce, Lu 0.8 Gd 1.2 SiO 5 :Ce and Lu 1.8 Gd 0.2 SiO 5 :Ce, respectively. The coincidence time spectra for 511 keV annihilation quanta were measured in reference to a fast BaF 2 detector and time resolution was discussed in terms of a number of photoelectrons and decay time of the fast component. The mass attenuation coefficient for studied crystals at 60 and 662 keV γ-rays was also evaluated and discussed.

In spite of the excellent performance of SiPMs in the application of time-of-flight PET detectors, the development of better photomultipliers for PET detectors is still worth considering. Fast timing with detectors based on the PMT light readout depends mainly on the time jitter and the quantum efficiency of the PMTs. Several studies in the past showed that a screening grid at the anode significantly improves the time resolution when measured with scintillation detectors. ADIT Co. has started a development of a 1” diameter fast PMT with the screening grid at the anode to be applied in the block detectors in TOF PET scanners. In the presented studies, we report the first comparative study of the L25, a classical PMT, with one that is equipped with a screening grid. Adding the screening grid yielded a large improvement in the time resolution, up to a factor of 1.2.

The scintillation timing characteristics of (La,Gd)2Si2O7:Ce (GPSLa23.5%:Ce) single crystal were studied and compared with Gd2SiO5:Ce (GSO:Ce) single crystal. The photoelectron yield, scintillation decay times and coincidence time resolution were measured. At 511 keV γ-rays, the photoelectron yield of 10,770 ± 500 phe MeV−1 and energy resolution of 5.4 ± 0.2% obtained for GPSLa23.5%:Ce are much better than those of 3350 ± 160 phe MeV−1 and 7.8 ± 0.3% obtained for GSO:Ce. The scintillation decay time profile was measured by the time-correlated single photon counting technique using a fast-slow coincidence setup. In both materials the comparable rise times of several nanoseconds are present. The fast component decay time of 56 ns with relative intensity of 49% obtained for GPSLa23.5%:Ce is inferior to that of 32 ns(88%) obtained for GSO:Ce. Consequently, the coincidence time resolution of GPSLa23.5%:Ce is slightly worse than that of GSO:Ce. The normalized time resolution was also discussed in terms of a number of photoelectrons and decay time of the scintillation pulse.

The timing characteristics of scintillation response of Czochralski-grown Gd 3 Al 2 Ga 3 O 12 :Ce and Gd 3 Al 2.6 Ga 2.4 O 12 :Ce single crystals were compared. The photoelectron yield, scintillation decay times, and coincidence time resolution were measured. At 662 keV γ-rays, the photoelectron yield of 6200 phe MeV −1 obtained for Gd 3 Al 2 Ga 3 O 12 :Ce is higher than that of 4970 phe MeV −1 obtained for Gd 3 Al 2.6 Ga 2.4 O 12 :Ce, while an inferior energy resolution of the former (7.2% vs. 5.6%) is observed. Scintillation decays are approximated by sum of exponentials with the dominant fast component decay time and its relative intensity of 89 ns (73%) for Gd 3 Al 2 Ga 3 O 12 :Ce and 136 ns (69%) for Gd 3 Al 2.6 Ga 2.4 O 12 :Ce. The coincidence time resolution obtained for Gd 3 Al 2 Ga 3 O 12 :Ce is superior than that of Gd 3 Al 2.6 Ga 2.4 O 12 :Ce. The normalized time resolution was also discussed in terms of a number of photoelectrons and decay characteristics of the light pulse.

According to the present knowledge, the non-proportionality of the light yield of scintillators appears to be the fundamental limitation of energy resolution. However, several observations collected in the last 15 years on the influence of slow components of the light pulses on energy resolution suggest more complex processes in the scintillators. The presented study of undoped CsI crystals shows a large deterioration of the intrinsic resolution of the crystal, when most of the light, including slow component was integrated. Moreover, it was confirmed by a large difference of the non-proportionality characteristics measured at short peaking time, corresponding to the integration of the fast intrinsic emission of the CsI, and that observed with a long peaking time, when the slow component was integrated.

According to current knowledge, the non-proportionality of the light yield of scintillators appears to be a fundamental limitation of energy resolution. A good energy resolution is of great importance for most applications of scintillation detectors. Thus, its limitations are discussed below; which arise from the non-proportional response of scintillators to gamma rays and electrons, being of crucial importance to the intrinsic energy resolution of crystals. The important influence of Landau fluctuations and the scattering of secondary electrons (δ-rays) on intrinsic resolution is pointed out here. The study on undoped NaI and CsI at liquid nitrogen temperature with a light readout by avalanche photodiodes strongly suggests that the non-proportionality of many crystals is not their intrinsic property and may be improved by selective co-doping. Finally, several observations that have been collected in the last 15 years on the influence of the slow components of light pulses on energy resolution suggest that more complex processes are taking place in the scintillators. This was observed with CsI(Tl), CsI(Na), ZnSe(Te), and undoped NaI at liquid nitrogen temperature and, finally, for NaI(Tl) at temperatures reduced below 0 °C. A common conclusion of these observations is that the highest energy resolution, and particularly intrinsic resolution measured with the scintillators, characterized by two or more components of the light pulse decay, is obtainable when the spectrometry equipment integrates the whole light of the components. In contrast, the slow components observed in many other crystals degrade the intrinsic resolution. In the limiting case, afterglow could also be considered as a very slow component that spoils the energy resolution. The aim of this work is to summarize all of the above observations by looking for their origin.

The article discusses damages of essential tribological associations in crankshaft and piston systems of large power two-stroke engines used as main engines, which take place during transport tasks performed by those ships. Difficulties are named which make preventing those damages impossible, despite the fact that the technical state of engines of this type is identified with the aid of complex diagnostic systems making use of advanced computer technology. It is demonstrated that one of causes of the damages is the lack of research activities oriented on recognising random properties of the loads leading to those damages. A proposal is made for the loads acting at a given time t on tribological associations in crankshaft and piston systems of internal combustion engines used as main engines to be considered as random variables Qt. At the same time the loads examined within a given time interval tr ≤ t ≤ tz would be considered stochastic processes {Q(t): t ≥ 0}. Essential properties of the loads of the abovementioned tribological associations are named and explained by formulating hypotheses which need empirical verification. Interval estimation is proposed for estimating the expected value E(Qt) of the load Qt acting at time t. A relation is indicated between the mechanical load and the thermal load acting on tribological associations in the ship main engine crankshaft and piston system. A suggestion is formulated that a stochastic form of the relation between these types of load is to be searched for, rather than statistic relation, and a proposal is made to measure the intensity (strength) of the stochastic relation using the Czuprow’s convergence coefficient.

Performance of Mg 2 + co-doped GAGG(Ce), hereafter called as cerium-doped gadolinium fine aluminum gallate, GFAG(Ce), in gamma-ray spectrometry has been investigated. The study of two samples of 10 × 10 × 5 mm 3 GFAG(Ce) crystals covers the tests of emission spectra, light output, non-proportionality, energy resolution, time resolution, and decay time of light pulses. The results obtained with the GFAG(Ce) were compared to the scintillators, such as GAGG(Ce), LSO(Ce), NaI(Tl), or LuAG(Pr). The measured light yield for tested GFAG(Ce) samples is 25000–27000 ph/MeV, with the energy resolution for 662 keV gamma-rays from 137Cs source of about 7%.

This paper presents the results of the proton irradiation of silicon photomulipliers (SiPMs) by mono-energetic 170 MeV protons with fluence up to 4.6$\times$10$^{9}$ particles/cm$^2$. In our work, three types of silicon photodetectors from Hamamatsu with areas 3$\times$3 mm$^2$ and different subpixel sizes of 25$\times$25 $\mu$m$^2$, 50$\times$50 $\mu$m$^2$, and 75$\times$75 $\mu$m$^2$ were used. The changes in the SiPM dark count rate (DCR) spectrum before and after irradiation in temperatures in the range of 20 $^\circ$C to -65 $^\circ$C are presented. The influence of the DCR changes on the energy resolution of the 662 keV gamma line from the $^{137}$Cs for a non-irradiated GAGG:Ce (1$\%$) scintillator is investigated. The time period of usability of the SiPM detector irradiated by protons in cosmic space was estimated.

The European H2020 project entitled “effective container inspection at border control point” (C-BORD) focuses on the development and in-situ tests of a comprehensive, cost-effective solution for the generalized non-intrusive inspection (NII) of containers and large-volume freight at the European Union border. The opening procedures of suspect containers are time consuming and expensive for economical and safety reasons; therefore, to reduce such operations, the C-BORD project aims to develop a set of technologies that can improve the quality of NII. Among these techniques, a tagged neutron inspection system is being developed in the C-BORD project. It will be a second-line defense system, to be used on sealed containers to detect explosives, illicit drugs, and chemical agents in suspect voxels (elementary volume units). This method employs a beam of tagged neutrons and a set of NaI(Tl) and LaBr[Formula: see text](Ce) scintillators, which will be used to detect prompt gamma rays produced by the neutron interactions. Here we report the advances on the development of the C-BORD’s rapidly relocatable tagged neutron inspection system, in particular the comprehensive characterization of the NaI(Tl) and LaBr[Formula: see text](Ce) gamma detectors (time and energy resolutions, high-count-rate behavior), the digital analysis for time-coincidence measurements and the data acquisition system (DAQ).

In this paper we present the prompt photofission neutron detection performance of undoped CaF2 scintillator using Threshold Activation Detection (TAD). The study is carried out in the frame of C-BORD Horizon 2020 project, during which an efficient toolbox for high volume freight non-intrusive inspection (NII) is under development. Technologies for radiation monitoring are the part of the project. Particularly, detection of various radiological threats on country borders plays an important significant role in Homeland Security applications. Detection of illegal transfer of Special Nuclear Material (SNM) - 235U, 233U and 239Pu - is particular due to the potential use for production of nuclear weapon as well as radiological dispersal device (RDD) V known also as a “dirty bomb”. This technique relies on activation of 19F nuclei in the scintillator medium by fast neutrons and registration of high-energy β particles and γ-rays from the decay of reaction products. The radiation from SNM is detected after irradiation in order to avoid detector blinding. Despite the low 19F(n,α)16N or 19F(n,p)19O reaction cross-section, the method could be a good solution for detection of shielded nuclear material. Results obtained with the CaF2 detector were compared with the previous study done for BaF2 and 3He detector. These experimental results were obtained using 252Cf source and 9 MeV Varian Linatron M9 linear accelerator (LINAC). Finally, performance of the prompt neutron detection system based on CaF2 will be validated at Rotterdam Seaport during field trails in 2018.

The linearity of a silicon photomultiplier (SiPM) response depends on the number of APD cells and its effective recovery time and it is related to the intensity and duration of the detected light pulses. The aim of this study was to determine the effective recovery time on the basis of the measured SiPM response to light pulses of different durations. A closer analysis of the SiPM response to the light pulses shorter than the effective recovery time of APD cells led to a method for the evaluation of the single photoelectron response of the devices where the single photoelectron peak cannot be clearly measured. This is necessary in the evaluation of the number of fired APD cells (or the number of photoelectrons) in measurements with light pulses of various durations. Measurements were done with SiPMs manufactured by two companies: Hamamatsu and SensL.

The purpose of this work is to present a measurement method for determining the neutron responses of various liquid organic scintillators using a time-of-flight technique in conjunction with a D–T neutron generator. The method is based on fast-neutron scattering on protons in a liquid-scintillator medium and on the acquisition of the neutron response of the medium as a function of the proton-recoil energy. This method can be applied to all scintillators that utilize fast-neutron elastic scattering.

WOS: 000348040900011, A new digital pulse-timing algorithm, to be used with the future neutron detector array NEDA, has been developed and tested. The time resolution of four 5 in diameter photomultiplier tubes (XP4512, R4144, R11833-100, and ET9390-kb), coupled to a cylindrical 5 in by 5 in BC501A liquict scintillator detector was measured by employing digital sampling electronics and a constant fraction discriminator (CFD) algorithm. The zero crossing of the CM algorithm was obtained with a cubic spline interpolation, which was continuous up to the second derivative. The performance of the algorithm was studied at sampling rates of 500 MS/s and 200 MS/s. The time resolution obtained with the digital electronics was compared to the values acquired with a standard analog CFD. The result of this comparison shows that the time resolution from the analog and the digital measurements at 500 MS/s and at 200 MS/s are within 15% for all the tested photomultiplier tubes. (C) 2014 Elsevier B.V. All rights reserved., Generalitat Valenciana, Spain [PROMETEO/2010/101, PROMETEO/2014/019]; MINECO, Spain [AIC-D-2011-0746, FPA2011-29854, FPA2012-33560]; STFC, UK; Swedish Research Council; Science and Technology Facilities Council [ST/L005727/1, ST/L005735/1, ST/J000124/1], Work partially supported by the Generalitat Valenciana, Spain, under grant PROMETEO/2010/101 and PROMETEO/2014/019, by MINECO, Spain, under grants AIC-D-2011-0746, FPA2011-29854 and FPA2012-33560, by the STFC, UK and by the Swedish Research Council.

We have studied the scintillation properties of cerium doped gadolinium aluminum gallium garnet (GAGG:Ce) scintillators with various Al-to-Ga ratio. Having many advantages, like high density (6.63 g/cm3), high light output, fair energy resolution and quite fast decay time, the scintillators are an excellent solution for gamma rays detection. In this paper performance of the GAGG:1%Ce crystals with different Al-to-Ga ratios is presented. The study covered measurements of emission spectra, light output, energy resolution and non-proportionality for each crystal. It was observed that the light output of the recently obtainable crystals varies from 40,000 to 55,000 ph/MeV. Maximum emission wavelength of about 520 nm promotes silicon based photodetectors for use with these scintillators. The best energy resolution of 3.7% at 662 keV, measured with Hamamatsu S8664-1010 APD, was obtained for the sample with the minimum gallium content. This result is close to these obtained with the group of scintillators retaining very good energy resolution, like LaCl3 and CeBr3.

The paper presents a novel design of a web-based Safe City & Coastal Zone GIS (SCCZ-GIS). The system integrates data acquired from different remote sensing and geospatial data sources for the purpose monitoring the security of the coastal zone, its inhabitants and critical infrastructure. The system utilizes several innovative technologies and solutions and is capable of direct co-operation with different remote sensing data sources and services, including satellite ground station and ESA Service Support Environment. The system runs in operational mode, and the results of the analysis are ready in quasi real time, that is, immediately after receiving a new scene of satellite imagery. The system may be accessed by authorized users either through a web-based client or mobile device application. The paper describes the architecture of the system and presents several case studies where the software is applied to processing of earth observation satellite and spatial analysis of coastal zone infrastructure.

International audience; In the frame of the C-BORD project, five innovate technology pillars for Non-Intrusive Inspection (NII) are under development. Freight containers are potential means for smuggling, drug trafficking and transport of dangerous or illicit substances. The goal of the C-BORD project is to increase interdiction of illicit or dangerous materials in containerized freight and deliver new capabilities against critical operational requirements and constrains. Particularly, the aim of the project is to increase throughput of the container per time unit, reduce cost and time of cargo inspection and minimize the false negative and false positive alarm ratios. Finally, thanks to field trials organized during the project, capability of these systems will be proven and the C-BORD Toolbox usefulness will be validated by end users under real conditions at sea and border crosses.

Evolution of spectroscopic properties of two types of Multi-Pixel Photon Counters (MPPC) during neutron irradiation is reported. In such experiments the change of MPPCs characteristics is a serious issue. A series of neutron irradiation tests were performed at the National Centre for Nuclear Research (NCBJ, Poland) and Joined Institute for Nuclear Research (JINR, Russia). Two types of neutron sources were used: PuBe with continous energy spectrum up to 11 MeV and mono-energetic 4.8 MeV neutrons produced in (d,d) reaction. For both cases the fluence in the range of 1010 n/cm2 was achived.