Spectroscopic performance of 4 types of large detectors consisting of 3 different scintillators (LaBr 3 , NaI(Tl) and BGO) coupled to large MPPC array are presented. The measurements are made with S12642-1616PB-50(X) Hamamatsu TSV MPPC array having a 50×50 μm 2 cell size and effective active area of 48×mm 2 (16×16 channels). In all measurements the common readout of all channels is used. The results obtained with MPPC, such as energy resolution and linearity, are compared with measurements of the same crystals on classic photomultiplier. Also the possible optimization of data acquisition electronics is presented.

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.

Timing resolution is one of the most important parameters of scintillation detectors in many applications One of the major fields in which timing resolution with SiPMs is studied are pixelated detectors for medical imaging and TOF PET. However there are many applications in which timing information from large, monolithic crystals is needed. The aim of this work is to study the timing resolution of large SiPM arrays in readout of various, monolithic scintillators. The presented measurements are made with S12642-1616PB-50(X) Hamamatsu TSV MPPC array having a 50×50 μm cell size and effective active area of 48×48 mm (16×16 channels). During the tests, MPPC is treated as a single/large detector. The different active areas of MPPC are achieved by readout of subareas of the device. In the first part of the study, experiments are made with the smallest 10×10×5 mm LSO scintillator and various number of readout channels in order to understand the influence of the detector area (or capacitance). Next, the timing spectra are recorded for 4 types of scintillators: CeBr 3 (1”, 2”), LaBr 3 (1”, 2”), Nal(Tl) (1”, 2”) and BC408 (2”). The optimization steps and the main aspects affecting the timing resolution of large MPPC arrays are discussed.

The paper presents the design, technology and parameters of a new, silicon 64-element linear photodiode array developed at the Institute of Electron Technology (ITE) for the detection of scintillations emitted by CsI scintillators (lambda approximate to 550 nm). The arrays are used in a device for examining the content of containers at border crossings under development at the National Centre for Nuclear Research. Two arrays connected with a scintillator block (128 CsI scintillators) form a 128-channel detection module. The array consists of 64 epiplanar photodiode structures (5.1 x 7.2 mm) and a 5.3 mm module. p(+)-nu-n(+) photodiode structures are optimised for the detection of radiation of lambda approximate to 550 nm wavelength with no voltage applied (photovoltaic mode). The structures are mounted on an epoxy-glass laminate substrate, copper-clad on both sides, on which connections with a common anode and separate cathode leads are located. The photosensitive surface of photodiodes is covered with a special silicone gel, which protects photodiodes against the mechanical impact of scintillators.

Pulse shape discrimination in scintillators is one of the most popular ways of recognizing events due to neutrons or gamma rays. Presently, n-γ discrimination is done mainly using two methods, charge comparison or zero-crossing. The aim of the study is to compare digital implementation of both algorithms using the same experimental data. For this purpose special application was developed in LabView environment which analyze the data digitized by Tektronix oscilloscope TDS5104B. The software allows optimization of each algorithm depending on the properties of the recorded pulse. The comparison is based on values of Figure of Merit and their relation to the light pulse characteristics. Both methods are used in measurements with XP5500B photomultiplier and Stilbene scintillator. Additionally the analysis of the detectors based on two types of Hamamatsu silicon photomultipliers (12×12mm2 and 24×24mm2) is presented. The results are compared with an analog zero-crossing system based on NDE202 NIM module.

The aim of this work is to provide the characteristics of MPPC as a part of neutron detector based on scintillators with n/γ discrimination capabilities. Measurements presented in the work cover: characterization of n/γ discrimination properties by means of Figure of Merit (FOM); comparison of scintillation light pulse shape measured with MPPC and PMT (rise time and fall time) and its influence on the ZC method; estimation of the number of photoelectrons per energy unit (phe/MeV) done by Bartolaccini method.

Heavy Ion Laboratory, University of Warsaw, 02-093 Warszawa, Poland Depart. of Physics and Astronomy, Uppsala University, 75120 Uppsala, Sweden GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany Université de Strasbourg, IPHC, 23 rue du Loess 67037 Strasbourg, France, CNRS, UMR7178, 67037 Strasbourg, France INFN, Laboratori Nazionali di Legnaro, 35020 Legnaro, Italy H. Niewodniczański Institute of Nuclear Physics PAN, 31-342 Kraków, Poland Faculty of Physics, University of Sofia, 1164 Sofia, Bulgaria Institut of Nuclear Research ATOMKI, Hungarian Academy of Sciences 4001 Debrecen, Hungary Department of Physics, University of Lund, 22100 Lund, Sweden Faculty of Physics, Warsaw University of Technology, 00-661 Warszawa, Poland CSNSM, Bâtiments 104 et 108, 91405 Orsay Cedex, France National Centre for Nuclear Research, 05-400 Otwock-Świerk, Poland

Odd-parity core excited states have been identified in two close neighbors of Sn-100: Pd-96 and Ag-97. This was done in an fusion-evaporation experiment, using a Ni-58 beam on a Sc-45 target. Even-parity core excited states in these nuclei are very well reproduced in large scale (LSSM) calculations in which particle-hole excitations are allowed with up to five g(9/2) protons and neutrons across the N = Z = 50 gap, to the g(7/2), d(5/2), d(3/2), and s(1/2) orbitals. The odd-parity states can only be qualitatively interpreted though, employing calculations in the full fpg shell model space, but with just one particle-hole core excitation allowed. A more complete model including odd-parity orbitals is need for the description of core excited states in the region of Sn-100. DOI:10.5506/APhysPolB.44.491 (Less)

The aim of this work is to provide the characteristics of MPPC arrays with an active area of 6 × 6 mm2 in gamma-ray spectrometry with CsI:Tl, LSO:Ce:Ca, LaBr3:Ce and BGO scintillators. The chosen scintillators have significantly different decay times of the scintillation pulses and different wavelengths of emission peaks. This allowed an investigation into the dependence of MPPC readout features on the MPPC and scintillator characteristics. The study of influence of effective dead time and the number of MPPC pixels on a readout response in relation to the brightness and speed of the scintillator were performed. The measurements covered a selection of MPPC optimum operating voltage, verification of the linearity range for a given decay time of the crystals, verification of the excess noise factor for the optimal voltage and evaluation of the Photon Detection Efficiency (PDE). The results of energy resolution and non-proportionality obtained with the MPPC array readout of CsI:Tl and BGO were compared to those obtained for the same crystals with the XP2020Q PMT readout. The results show that an MPPC can be used as effectively as a PMT for gamma spectrometry measurements in the whole tested energy ranges (up to 1.3 MeV) and for many types of scintillation crystals (BGO, CsI:Tl).

The aim of this work is to provide the characteristics of MPPC arrays with an active area of 6 x 6 mm(2) in gamma-ray spectrometry with CsI:Tl, LSO:Ce:Ca, LaBr3:Ce and BGO scintillators. The chosen scintillators have significantly different decay times of the scintillation pulses and different wavelengths of emission peaks. This allowed an investigation into the dependence of MPPC readout features on the MPPC and scintillator characteristics. The study of influence of effective dead time and the number of MPPC pixels on a readout response in relation to the brightness and speed of the scintillator were performed. The measurements covered a selection of MPPC optimum operating voltage, verification of the linearity range for a given decay time of the crystals, verification of the excess noise factor for the optimal voltage and evaluation of the Photon Detection Efficiency (PDE). The results of energy resolution and non-proportionality obtained with the MPPC array readout of CsI: Tl and BGO were compared to those obtained for the same crystals with the XP2020Q PMT readout. The results show that an MPPC can be used as effectively as a PMT for gamma spectrometry measurements in the whole tested energy ranges (up to 1.3 MeV) and for many types of scintillation crystals (BGO, CsI:Tl).

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.

Citation for published version (APA): Palacz, M., Nyberg, J., Grawe, H., Sieja, K., de Angelis, G., Bednarczyk, P., Blazhev, A., Curien, D., Dombradi, Z., Dorvaux, O., Ekman, J., Galkowski, J., Gorska, M., Iwanicki, J., Jaworski, G., Kownacki, J., Ljungvall, J., Moszynski, M., Nowacki, F., ... Zieblinski, M. (2012). N=50 Core Excited States Studied in the 96Pd Nucleus. Physical Review C (Nuclear Physics), 86(1), [014318]. https://doi.org/10.1103/PhysRevC.86.014318

The four-proton hole Pd-96 neighbor of the doubly-magic Sn-100 nucleus was studied in-beam, using a fusion-evaporation reaction of a Ni-58 beam on a Sc-45 target. States of Pd-96 were established up to an excitation energy of 9707 keV. A core-excited odd-parity isomer with T-1/2 = 37.7(1.1) ns was identified. Shell model calculations were performed in four different model spaces. Even-parity states of Pd-96 are very well reproduced in large-scale shell model (LSSM) calculations in which excitations are allowed of up to five g(9/2) protons and neutrons across the N = Z = 50 gap, to the g(7/2), d(5/2), d(3/2), and s(1/2) orbitals. The odd-parity isomer can be only qualitatively interpreted though, employing calculation in the full fpg shell model space, with just one particle-hole core excitation.

The aim of this work is to provide the characteristics of MPPC arrays with an active area of 6 × 6 mm2 in gamma-ray spectrometry with CsI:Tl, LSO:Ce:Ca, LaBr3:Ce and BGO scintillators. The chosen scintillators have significantly different decay times of the scintillation pulses and different wavelengths of emission peaks. This allowed an investigation into the dependence of MPPC readout features on the MPPC and scintillator characteristics. The study of influence of effective dead time and the number of MPPC pixels on a readout response in relation to the brightness and speed of the scintillator were performed. The measurements covered a selection of MPPC optimum operating voltage, verification of the linearity range for a given decay time of the crystals, verification of the excess noise factor for the optimal voltage and evaluation of the Photon Detection Efficiency (PDE). The results of energy resolution and non-proportionality obtained with the MPPC array readout of CsI:Tl and BGO were compared to those obtained for the same crystals with the XP2020Q PMT readout. The results show that an MPPC can be used as effectively as a PMT for gamma spectrometry measurements in the whole tested energy ranges (up to 1.3 MeV) and for many types of scintillation crystals (BGO, CsI:Tl).

The four-proton hole ${}^{96}\mathrm{Pd}$ neighbor of the doubly-magic ${}^{100}\mathrm{Sn}$ nucleus was studied in-beam, using a fusion-evaporation reaction of a ${}^{58}\mathrm{Ni}$ beam on a ${}^{45}\mathrm{Sc}$ target. States of ${}^{96}\mathrm{Pd}$ were established up to an excitation energy of 9707 keV. A core-excited odd-parity isomer with ${T}_{1/2}=37.7(1.1)$ ns was identified. Shell model calculations were performed in four different model spaces. Even-parity states of ${}^{96}\mathrm{Pd}$ are very well reproduced in large-scale shell model (LSSM) calculations in which excitations are allowed of up to five ${g}_{9/2}$ protons and neutrons across the $N=Z=50$ gap, to the ${g}_{7/2}$, ${d}_{5/2}$, ${d}_{3/2}$, and ${s}_{1/2}$ orbitals. The odd-parity isomer can be only qualitatively interpreted though, employing calculation in the full $fpg$ shell model space, with just one particle-hole core excitation.

Recently, a silicon photomultiplier (SiPM) became one of the strongest candidates for application in PET–MR or SPECT–MR dual-modality scanners. However, optimization of the scintillation detectors with SiPM light readout requires different approach than in the case of classic photomultipliers. The finite number of micro-cells in a SiPM creates nonlinear response for high number of incident photons. Moreover, the size and total number of micro-cells defines fill factor, which in turn affects the photon detection efficiency (PDE). Response of SiPMs is also highly sensitive to bias voltage causing changes in PDE and excess noise factor (ENF). Finally, each cell posses an effective dead time needed to fully recharge that cell after the photon detection. In this work the listed above unique features of SiPMs are overviewed. The reported data also contain measurements of energy resolution and 22Na time resolution.

The aim of this work is characterization of MPPC arrays with active area of 6×6 mm in gamma-ray spectrometry with four scintillators CsI(Tl), LSO:Ce(Ca), LaBr3 and BGO. The chosen scintillators have significantly different decay times of a scintillation pulse and different wavelength of emission peaks. It allowed study of the influence of MPPC effective dead time on a device response and calculation of a Photon Detection Efficiency (PDE) of MPPC. The measurements covered : a selection of the optimum operating voltage, a verification of the linearity range for a given decay time of the crystals, a verification of the excess noise factor for the optimal voltage and calculation of the PDE of MPPC. Measurements of energy resolution and non-proportionality obtained with the MPPC arrays and CsI(Tl) or BGO were compared to the similar measurements performed with XP2020Q PMT.

The aim of the work is to investigate the revised concept of a neutron detector, offered by Saint Gobain-the BC-704 scintillation screen with a light readout by Wavelength Shifting (WLS) fibers. This detector was developed as a replacement of helium tubes, due to the lack of 3He on the world market. It is characterized by high sensitivity to gamma-rays, but the events from neutrons and gammas are well separated. Measurements with gamma and neutron sources have been performed and the results have been compared with helium-3 counter. According to American National Standards Institute (ANSI), we obtained n/γ discrimination on the level of 10-10, whereas absolute neutron detection efficiency was estimated as approximately two times higher than in the case of the reference 3He tube without the moderator. The tested detector is a sample prototype of one detector configuration of many possible, and that it can be modified to the neutron efficiency specification required.

The linear response of the silicon photomultiplier (SiPM) device depends on the number of APD cells, their effective dead time and is related to a width of the detected light pulses or a decay time of a scintillation crystal. The aim of this work was determination of the effective dead time of APD cells on the basis of the measured linear response of the SiPM for light pulses of different width. A closer analysis of the SiPM response to the light pulses shorter than the effective dead time of pixels, made possible evaluation of a number of fired pixels (or number of photoelectrons) in cases when a single photoelectron peak was not well defined. This analysis also allows determination of the position of the single photoelectron peak, necessary in case of measurements of the number of photoelectrons for light pulses with various widths. Measurements were done with SiPMs manufactured by three companies: Hamamatsu, Zecotek and SensL.