T. Szczesniak

National Centre for Nuclear Research, Warszawa, Masovian Voivodeship, Poland

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Publications (75)52.21 Total impact

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    ABSTRACT: In the paper we reported on the scintillation properties and pulse shape discrimination (PSD) performance of new plastic scintillators. The samples with dimension of 2 inches × 2 inches were tested: EJ299-34, EJ299-34G, EJ299-33 and EJ299-33G. They are the first commercially available plastics with neutron/gamma discrimination properties. The paper covers the measurements of emission spectra, photoelectron yield, analysis of the light pulse shapes originating from events related to gamma-rays and fast neutrons as well as neutron/gamma discrimination. The tested plastics are characterized by a photoelectron yield on a level of approximately 1600-2500 phe/MeV, depending on the sample. The highest value, measured for EJ299-34, is similar to the number of photoelectrons measured for EJ309 (2600 phe/MeV). The figure of merit (FOM) calculated for narrow energy cuts — indicating the PSD performance — showed that the PSD capabilities of the plastics are significantly lower than of EJ309. These scintillators are still under development in order to optimize the composition and manufacturing procedures. At this time the results obtained with the new plastics suggest their possible use as an alternative for liquid scintillators, especially if we consider their inflammability and non-toxicity.
    Journal of Instrumentation 06/2014; 9(06):P06014. · 1.66 Impact Factor
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    ABSTRACT: The scintillation characteristics of Lu1.95Y0.05SiO5:Ce (LYSO:Ce) and Lu0.7Y0.3AlO3:Ce (LuYAP:Ce) single crystals were compared for γ-ray detection. The values of scintillation decay time and coincidence time resolution were evaluated. The scintillation decay of LYSO:Ce exhibits approximately a single-exponential component with decay time of 39 ns, whereas for LuYAP:Ce an intensity of the fast component with decay time of 21 ns is reduced (∼42%) and followed by a high intensity of slower components. The coincidence time resolution for 511 keV annihilation quanta of 234 and 894 ps was obtained, respectively, for LYSO:Ce and LuYAP:Ce detectors in coincidence experiment using a BaF2-based detector. The time resolution was also discussed in terms of a number of photoelectrons and decay time of the scintillation pulse.
    Nuclear Instruments and Methods in Physics Research Section B Beam Interactions with Materials and Atoms 01/2014; · 1.19 Impact Factor
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    ABSTRACT: This study presents a simple experimental setup for precise inspection of scintillation decay characteristics as a function of the energy deposited in scintillators. The results are discussed for NaI:Tl, LSO:Ce and CeBr3 crystals. The tested samples were coupled to a fast response R5320 photomultiplier from Hamamatsu. The decay time constants were measured by fitting the anode pulses of the PMT registered directly with a TDS5054B digital oscilloscope from Tektronix. Simple analog electronics composed of timing single channel analyzers, gate generators and coincidence/logic unit was used for selection of the deposited energy converted into light within the scintillator, and for triggering the scope to register relevant scintillation pulses. High precision of the experimental setup allowed for registration of non-proportionality curves for all samples. Moreover, non-proportionality was measured for fast and slow decay mode of NaI:Tl separately. The measurement was also used for inspection of possible differences in the pulse shapes originating from Compton scattering events and photoabsorption.
    Nuclear Instruments and Methods in Physics Research 01/2014; A749:68.
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    Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment 01/2014; A749:68. · 1.14 Impact Factor
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    ABSTRACT: Commercial LYSO:Ce,Ca and YSO:Ce single crystals are compared.Ca2+ codoping in LYSO:Ce,Ca converts a part of the Ce3+ centers into Ce4+.Ce4+ center is not harmful for scintillation efficiency in LYSO:Ce,Ca.YSO:Ce scintillation response is deteriorated by slower host-Ce energy transfer.
    Optical Materials 07/2013; 35(9):1679-1684. · 2.08 Impact Factor
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    ABSTRACT: The absorption, luminescence, and scintillation characteristics of cerium-doped lutetium-yttrium perovskite (LuxY1�x AlO3: Ce; x ¼ 0, 0.3, 0.7) single crystals were investigated. The values of light yield, scintillation decay time, and coincidence time resolution were evaluated. At 662 keV g-rays (137Cs source), the light yield of 30 700 ph MeV�1 obtained for YAlO3:Ce is much higher than that of 16 200 and 10 600 ph MeV�1 obtained for Lu0.3Y0.7AlO3:Ce and Lu0.7Y0.3AlO3:Ce, respectively. Scintillation decays are dominated by a fast component with decay time value of 16–20 ns, which nearly coincides with the photoluminescence decay time value of 17.5 ns. In scintillation decays the intensity of the fast component becomes reduced and the content of slower components considerably increased with increasing lutetium content in the crystals. The coincidence time spectra for 511 keV annihilation quanta were measured in coincidence experiment using a BaF2-based detector and time resolution was also discussed in terms of a number of photoelectrons and decay time of the scintillation pulse. The photofraction for all the crystals under 662 keV g-ray excitation was also evaluated and discussed.
    physica status solidi (a) 06/2013; 210(9):1903-1908. · 1.21 Impact Factor
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    ABSTRACT: Performance of cerium-doped Gd3Al2Ga3O12 (GAGG:Ce) scintillator in gamma-ray spectrometry has been investigated. The measurements of two samples of GAGG:Ce cover the tests of emission spectra (maximum of emission at about 530 nm), light output, non-proportionality, energy resolution, time resolution and decay time of light pulses. We compare the results with commonly known scintillators, such as NaI(Tl), LSO, LuAG etc. The results show that GAGG:Ce has a high light yield of about 33000 ph/MeV as measured with Hamamatsu S3590–18 Si PiN photodiode [1]. The total energy resolution for 662 keV gamma-rays from 137Cs source is equal to about 6%, whereas intrinsic resolution is equal to 5.2%. Additionally, we made basic measurements of photoelectron yield, non-proportionality and total energy resolution of small sample (5×5×5 mm3) of GAGG:Ce crystal coupled to Hamamatsu MPPC array (6×6 mm2). The results show that the performance of GAGG:Ce measured with the MPPC array are similar to those measured with the PMT.
    Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment 06/2013; 712:34–40. · 1.14 Impact Factor
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    ABSTRACT: Presently, a majority of studies concerning application of silicon photomultipliers (SiPMs) in positron emission tomography detectors are focused on scintillators containing lanthanum (LaBr3) or lutetium (LSO, LYSO, LFS). However, the modules with the well known BGO in combination with SiPM light readout are also interesting due to unique features of SiPMs. In this work the two types of detectors, based on BGO and LSO scintillators are compared in terms of requirements for positron emission tomography scanners. The presented studies are performed with two Hamamatsu Multi Pixel Photon Counter (MPPC) arrays of 2×2 channels, with total area of 6×6 mm2 and micro-pixel size of 25 µm (S10985-025C) and 50 µm (S10985-050C). The measurements of a number of photoelectrons, energy resolution at 511 keV and 22Na time resolution are reported for various sizes of scintillators, including 3×3 mm2 pixels and single crystals covering the whole MPPC active area. The paper is more focused on optimization of the system with BGO since its performance in combination with SiPM light readout is less known. The aim of this work is to show advantages of a SiPM based detector, especially in combination with BGO, in respect to the block detectors where classic photomultipliers are used.
    IEEE Transactions on Nuclear Science 06/2013; 60(3). · 1.22 Impact Factor
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    ABSTRACT: Relative light yield and intrinsic energy resolution of NaI:Tl, CsI:Na and CsI:Tl crystals were investigated by means of the wide angle Compton coincidence technique in wide energy range from several keV up to 1 MeV. The experimental setup consisted of a high purity germanium (HPGe) detector and the tested scintillators were put at a close separation from the HPGe detector. The tested samples were cylinders of 25 mm diameter and height coupled to a photomultiplier. Compton electron responses were compared to the results obtained with γ-ray absorption peaks. A correlation between intrinsic resolution of the tested scintillation materials and their nonproportionality was observed. Substantial differences in intrinsic resolution measured for γ-ray absorption peaks and Compton electrons were registered in the energy range between 50 keV and 200 keV. The results were discussed in terms of electron scattering, pointing to δ-ray production as an important contribution for determination of scintillator intrinsic resolution.
    Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment 03/2013; 705:42–46. · 1.14 Impact Factor
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    ABSTRACT: A development of silicon photomultipliers (SiPM), with a large number of micro-pixels and improved linearity of the pulse height response, allow discussing their possible application to gamma spectrometry with scintillators. Most of the measurements were done with Hamamatsu MPPCs sensors equipped with 3600 and 14400 pixels because of their well pronounced single photoelectron spectra. It allowed precisely measure the photoelectron (phe) numbers/fired pixels and then to discuss in a quantitative manner an obtainable energy resolution. The studied detectors were characterized first by means of a laser light pulser and then by 3×3×3 mm3 LFS and CsI(Tl) crystals coupled to 3×3 mm2 Hamamatsu MPPC. In the study with the light pulser, the linearity of the MPPC response, expressed in the photoelectron number measured in relation to the first photoelectron, versus a light pulse intensity observed with PMT was checked and then the pulse height resolution was measured. Through analysis of the energy resolution the lower limit of the phe number was derived, assuming Poisson statistic. Further on, based on a directly measured phe number, the discussion of an excess noise factor of MPPC was done. In scintillation tests the measurements of the energy resolution and non-proportionality of the light yield were done with LFS and CsI(Tl) and discussed in a quantitative way, based on the measured PHE number, for both types of 3×3 mm2 MPPC detectors.
    Journal of Instrumentation 02/2013; 8(02). · 1.66 Impact Factor
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    Journal of Instrumentation 01/2013; P09020. · 1.66 Impact Factor
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    IEEE Transactions on Nuclear Science 12/2012; 59(6):3294-3303. · 1.22 Impact Factor
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    ABSTRACT: The aim of this work is to provide the characteristics of MPPC arrays with an active area of 6x6 mm2 in gamma-ray spectrometry with 5x5x5mm3 CsI:TI scintillator at a wide temperature range. The measurements presented in this work covered: characteristics of breakdown voltage, selection of MPPC optimum operating voltage, verification of excess noise factor, measurement of energy resolution and the number of photoelectrons per 1 MeV. All measurements were carried out as a function of temperature and compared with similar results obtained previously with CsI:TI crystal coupled to a Large Area Photodiode (LAAPD).
    Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC), 2012 IEEE; 01/2012
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    ABSTRACT: Non-proportionality of light yield and energy resolution of Compton electrons in three scintillators (LaBr$_{3}$ :Ce, LYSO:Ce and CsI:Tl) were studied in a wide energy range from 10 keV up to 1 MeV. The experimental setup was comprised of a High Purity Germanium detector and tested scintillators coupled to a photomultiplier. Probing the non-proportionality and energy resolution curves at different energies was obtained by changing the position of various radioactive sources with respect to both detectors. The distance between both detectors and source was kept small to make use of Wide Angle Compton Coincidence (WACC) technique, which allowed us to scan large range of scattering angles simultaneously and obtain relatively high coincidence rate of 100 cps using weak sources of about 10 $\mu$Ci activity. The results are compared with those obtained by direct irradiation of the tested scintillators with gamma-ray sources and fitting the full-energy peaks.
    IEEE Transactions on Nuclear Science 01/2012; 59(1):222-229. · 1.22 Impact Factor
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    ABSTRACT: The quest for choosing the suitable detector for a specific homeland security application that takes an advantage of the neutron activation analysis technique prompted us to investigate properties of three $3^{\prime\prime}\times 3^{\prime\prime}$ cylindrical scintillation detectors. The emphasis was put on the detectors' properties in the multi-MeV energy region and their response to the neutron radiation. In this work we compare the energy resolution, efficiency and timing properties of BGO, ${\hbox {LaBr}}_{3}$ and NaI(Tl) scintillation detectors coupled to Photonis spectrometric photomultiplier tubes.
    IEEE Transactions on Nuclear Science 01/2012; 59(1):230-235. · 1.22 Impact Factor
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    ABSTRACT: Light yield nonproportionality and the intrinsic resolution of some low atomic number scintillators were studied by means of the Wide Angle Compton Coincidence (WACC) technique. The plastic and liquid scintillator response to Compton electrons was measured in the energy range of 10 keV up to 4 MeV, whereas a CaF2:Eu sample was scanned from 3 keV up to 1 MeV. The nonproportionality of the CaF2:Eu light yield has characteristics typical for inorganic scintillators of the multivalent halides group, whereas tested organic scintillators show steeply increasing nonproportionality without saturation point. This is in contrast to the behavior of all known inorganic scintillators having their nonproportionality curves at saturation above energies between tens and several hundred keV.
    Journal of Instrumentation 01/2012; 7(06). · 1.66 Impact Factor
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    ABSTRACT: Two samples of 10 mm diameter and 10 mm height CdWO4 and ZnWO4 scintillators were studied at room and liquid nitrogen temperatures. At room temperature the crystals were coupled to a Photonis XP3212 photomultiplier. During experiments at low temperatures a Large Area Avalanche Photodiode was used as a photodetector. Measurements of light output, non-proportionality of the light yield and intrinsic resolution as a function of gamma-ray energies were performed at both temperatures. The non-proportionality for the two crystals reveals temperature dependence, showing a more proportional behavior at liquid nitrogen temperature. Intrinsic energy resolution values for both crystals also show temperature dependence.
    Journal of Instrumentation 01/2012; 7(03). · 1.66 Impact Factor
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    ABSTRACT: Time jitter, it means timing distribution of a detector response to single photons is one of the key parameters describing the timing resolution capabilities of any photodetector. In this work, the time jitter measurements of silicon photomultipliers (SiPMs) with active area from 1 to 36 mm2 are presented. These measurements were made using fast picosecond laser PicoQuant LDH P C-405 with wavelength of 405 nm and pulse width below 70 ps. The measurements were done with Hamamatsu Multi-Pixel Photon Counters (MPPCs) with micropixel size of 50 μm (050C). Additional data were also recorded when only a part of an active area of the tested MPPCs was illuminated. The MPPC output was fed into fast amplifier MiniCircuits ERA-4SM+ with 4GHz bandwidth and then further amplified by NIM modules and processed by constant fraction discriminator. In each experiment the noise component was measured and subtracted from the raw timing data. The aim of the study was to understand the influence of the SiPM's capacitance and rise time on the time jitter and also to distinguish differences resulting from the electronics optimization from those due to physical effects connected with an active or illuminated area of a detector.
    Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC), 2012 IEEE; 01/2012
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    ABSTRACT: The relation between non proportional response of the scintillators and their energy resolution has been extensively studied in the last years. However, there is not much data on the scintillation decay characteristics as a function of the energy deposited in the scintillator. This study presents a simple experimental setup for direct registration of the scintillation pulse shapes. The tested scintillators are coupled to a photomultiplier. Anode pulses are recorded directly by a digital oscilloscope. The scope is triggered by a logic signal from a single channel analyzer, employed to ensure precise selection of the energy deposit. The study is aimed at investigating the decay time constants and intensities of scintillation decay components as a function of the energy deposited in the scintillator. The differences in the pulse shapes generated in the Compton scattering and photoabsorption processes are also inspected. In this study we present the results of the test case study performed for NaI:TI scintillator.
    Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC), 2012 IEEE; 01/2012