G. Kalinka

Hungarian Academy of Sciences, Budapeŝto, Budapest, Hungary

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Publications (65)119.55 Total impact

  • Physical Review C 04/2014; 89(4). DOI:10.1103/PhysRevC.89.044310 · 3.88 Impact Factor
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    ABSTRACT: Excited states of 80Br have been investigated via the 76Ge(11B, α3n) reaction and a new ΔI = 1 band has been identified which resides ˜ 400 keV above the yrast band. Based on the experimental results, a chiral character of the two bands within the πg9/2 ⊗ νg9/2 configuration is proposed, which provides the first evidence for chirality in the A ˜ 80 mass region.
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    ABSTRACT: A neutron spectrometer, the European Low-Energy Neutron Spectrometer (ELENS), has been constructed to study exotic nuclei in inverse-kinematics experiments. The spectrometer, which consists of plastic scintillator bars, can be operated in the neutron energy range of 100 keV to 10 MeV. The neutron energy is determined using the time-of-flight technique, while the position of the neutron detection is deduced from the time-difference information from photomultipliers attached to both ends of each bar. A novel wrapping method has been developed for the plastic scintillators. The array has a larger than 25% detection efficiency for neutrons of approximately 500 keV in kinetic energy and an angular resolution of less than 1 degree. Details of the design, construction and experimental tests of the spectrometer will be presented.
    Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment 10/2013; 736. DOI:10.1016/j.nima.2013.10.038 · 1.32 Impact Factor
  • Physical Review C 04/2013; 87(4):044328. DOI:10.1103/PhysRevC.87.044328 · 3.88 Impact Factor
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    ABSTRACT: A complete kinematics measurement was performed using the 6Li(3He,t) charge exchange reaction to populate 6Be at Elab = 50 MeV. Decay mode of the ground and first excited states were studied through the analysis of the energy and angular distributions of the break-up particles in the 6Be center of mass frame. Two-body decay is observed above the first excited state but not firmly assigned to a 6Be resonant state. Experimental challenges regarding the identification of true 6Be events in the excitation energy region 5 < Ex < 20 MeV are discussed.
    International Journal of Modern Physics E 05/2012; 20(04). DOI:10.1142/S0218301311019210 · 0.84 Impact Factor
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    ABSTRACT: The high-spin structure of the nucleus Pd-104 was studied through the Zr-96(C-13,5n) reaction at incident energies of 51 and 58MeV, using the Euroball IV gamma-ray spectrometer in conjunction with the DIAMANT charged-particle array. Several new medium- and high-spin bands were revealed. The already known positive-parity yrast and the negative-parity cascades were extended up to E-x similar to 13, similar to 11, and similar to 9 MeV with I-pi = (26(+)), I-pi = (23(-)), and (20(-)), respectively. The deduced band structures were compared with Woods-Saxon total Routhian surface (TRS) calculations. In addition, non-yrast low-lying positive-parity bands were identified, which were assigned to soft gamma-vibrational excitations.
    Physical Review C 04/2012; 85(4). DOI:10.1103/PhysRevC.85.044303 · 3.88 Impact Factor
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    ABSTRACT: Combined PET-MRI scanners start a new era in medical imaging. However the development of MRI compatible PET detector module is a challenging task. SiPM sensors are insensitive to magnetic field and constitute a promising solution. A drawback is the high dark current. A readout concept for SiPM based small animal PET detector module is presented in this paper. The results show that the readout of the SiPM is possible using only four ADC channels and the position map is comparable to the ideal solution. The detector modules based on the method are feasible solution for MRI compatible PET scanners.
    Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC), 2012 IEEE; 01/2012
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    ABSTRACT: We report on the development of an evaluation detector module built for our miniPET -3 small animal PET scanner. The module is based on an LySO scintillation matrix exactly matching that used in miniPET-II (so that the performance of the two PET scanners is easier to compare), followed by a Silicon Photomultiplier (SiPM) matrix array. The front-end electronics is designed to be modular, so that different readout concepts can be evaluated and prototype-tested. The readout electronics is based on a system-on-module with Spartan-6 FPGA and Gigabit Ethernet connectivity. Different SiPM readout concepts were tested using the module, and based on the evaluation results one was selected for implementation and testing.
    Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC), 2012 IEEE; 01/2012
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    ABSTRACT: Excited states of $^{80}$Br have been investigated via the $^{76}$Ge($^{11}$B, $\alpha$3n) and $^{76}$Ge($^{7}$Li, 3n) reactions and a new $\Delta I$ = 1 band has been identified which resides $\sim$ 400 keV above the yrast band. Based on the experimental results and their comparison with the triaxial particle rotor model calculated ones, a chiral character of the two bands within the $\pi g_{9/2}\otimes \nu g_{9/2}$ configuration is proposed, which provides the first evidence for chirality in the $A\sim80$ region.
    Physics Letters B 09/2011; 703(1):40-45. DOI:10.1016/j.physletb.2011.07.055 · 6.02 Impact Factor
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    ABSTRACT: Two demonstrators, a spiralCT and a miniPET, have been designed and constructed for educational purposes. Computed tomographs (CTs) and positron emission tomographs (PETs) are some of the most commonly used structural and functional imaging devices in medicine, respectively. There is a need for transparent demonstrators where the principles of the different modalities and their functions are presented. The aim of the developments of these systems was to present the major building blocks of CT and PET for undergraduate students. Photon detection in both systems is based on small pixelised scintillation crystals with position sensitive PMT readout. Similar analogue and digital data processing based on FPGA technique is applied for the demonstrators and common image reconstruction and presentation software components are used.
    Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment 05/2011; 633:S300–S302. DOI:10.1016/j.nima.2010.06.195 · 1.32 Impact Factor
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    ABSTRACT: Shell structure and magic numbers in atomic nuclei were generally explained by pioneering work that introduced a strong spin-orbit interaction to the nuclear shell model potential. However, knowledge of nuclear forces and the mechanisms governing the structure of nuclei, in particular far from stability, is still incomplete. In nuclei with equal neutron and proton numbers (N = Z), enhanced correlations arise between neutrons and protons (two distinct types of fermions) that occupy orbitals with the same quantum numbers. Such correlations have been predicted to favour an unusual type of nuclear superfluidity, termed isoscalar neutron-proton pairing, in addition to normal isovector pairing. Despite many experimental efforts, these predictions have not been confirmed. Here we report the experimental observation of excited states in the N = Z = 46 nucleus (92)Pd. Gamma rays emitted following the (58)Ni((36)Ar,2n)(92)Pd fusion-evaporation reaction were identified using a combination of state-of-the-art high-resolution γ-ray, charged-particle and neutron detector systems. Our results reveal evidence for a spin-aligned, isoscalar neutron-proton coupling scheme, different from the previous prediction. We suggest that this coupling scheme replaces normal superfluidity (characterized by seniority coupling) in the ground and low-lying excited states of the heaviest N = Z nuclei. Such strong, isoscalar neutron-proton correlations would have a considerable impact on the nuclear level structure and possibly influence the dynamics of rapid proton capture in stellar nucleosynthesis.
    Nature 01/2011; 469(7328):68-71. DOI:10.1038/nature09644 · 42.35 Impact Factor
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    ABSTRACT: The factors determining the position resolution of continuous crystal based position sensitive scintillation gamma detectors are discussed. The key factors are the position functions which give the relation between the coordinates of the point of interaction (POI) and the responses of the photodetectors reading out of the scintillator. The physical phenomena limiting the position resolution are the statistical fluctuation of the detected photons and the electronic noise. For the standard deviation of the POI coordinates simple relations are deduced. It has been established that the contributions of both the statistical fluctuation and the noise to the standard deviation of the POI coordinates are inversely proportional to the square root of the detected photon numbers and the measure of these contributions can be characterised with the position resolution coefficients deduced from the position functions. A detailed discussion of the effect of the scintillator and photodetector characteristics is also given. As an example, calculations for the resolution coefficients in the case of the solid angle method with a chosen scintillator photodetector arrangement are given. The results show that the resolution coefficients as a function of the POI coordinates vary in a wide range. With realistic practical data and using almost the largest value for the resolution coefficients similar or better position resolution can be reached with continuous crystal than with a pixellated one.
    01/2011; DOI:10.1109/NSSMIC.2011.6153695
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    ABSTRACT: A complete kinematic measurement of the 6Li(3He,3H)αpp reaction is performed at Elab=50 MeV, to investigate the cluster structure of 6Be. The energy and angular distributions of the breakup particles, emitted from the ground and first excited states of 6Be, are compared to three-body resonance and two-body sequential decay calculations. The results indicate a rather pure three-body configuration of the 2+ state of 6Be but they are not conclusive regarding the decay mode of the 0+ state. No branching ratio between sequential and three-body decay paths could be extracted. Excitations above the 2+ state were populated at Ex=1.67–23 MeV. Decay through 5Li-p and 2He-4He channels is identified in the continuum of 6Be, and the reaction mechanism is discussed.
    Physical Review C 05/2010; 81(5). DOI:10.1103/PhysRevC.81.054308 · 3.88 Impact Factor
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    ABSTRACT: We report on the implementation of an interleaving TDC architecture based on Virtex-4 ISERDES blocks. Multiple ISERDES blocks are used for each input channel in a split-phase arrangement. The architecture has moderate resolution (312 ps in this implementation), it is not sensitive to PVT variations, requires only limited FPGA resources, and thus suitable for high channel counts.
    IEEE Nuclear Science Symposium conference record. Nuclear Science Symposium 01/2010; DOI:10.1109/NSSMIC.2010.5874005
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    ABSTRACT: We report on a Synchronous Ethernet based clock distribution and timestamp synchronization implementation over 1000BASE-T (Gigabit over twisted pair) Ethernet. A central 125 MHz global clock is distributed to all detector modules using only commercial off-the-shelf components. The timestamps generated on different modules has a maximum fixed offset of 24–60 ns (depending on the switch tested), and a jitter of less than 500 ps (with no clock cleaner IC being used).
    IEEE Nuclear Science Symposium conference record. Nuclear Science Symposium 01/2010; DOI:10.1109/NSSMIC.2010.5874287
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    ABSTRACT: The electrical properties and spectral response of a Hamamatsu S5821 silicon PIN photodiode were investigated in-situ during and after irradiation by 430 keV H(+) 2.15 MeV Li(2+), 4 MeV O(3+) and 6.5 MeV O(4+) ion beams focused to a sub-micrometer beam size. Ion species and their respective energies were selected to approximately have the same end range of 5 mu m within the depletion region of the unbiased photodiode. Particle irradiation fluences (Phi) of 10(8) to 10(12) cm(-2) were selected, such that displacement damage dose (D(d)) values within the material had a similar range of 10(10) to 10(13) MeV/g for the selected particles. Under these conditions, it has been observed that protons produce the largest increase in device capacitance. At 100 V an increase in the generation current from 2.3 nA/cm(2) for a unirradiated sample to 1.7 mu A/cm(2), 2.4 mu A/cm(2), and 3 mu A/cm(2) for samples irradiated by protons, lithium, and oxygen ions, respectively, was determined for a displacement damage dose of 3.9 x 10(11) MeV/g. The ion beam-induced charge (IBIC) technique was used to investigate the charge collection efficiency (CCE) of the irradiated photodiodes. The irradiation-induced changes of the CCE for both protons and oxygen were compared with respect to the non-ionizing energy loss (NIEL), which is a good measure of displacement damage introduced into a material by ionizing particles. The measured reduction of the pulse height with increasing displacement damage dose was fitted to a radiation damage function. The calculated equivalent damage factors, K(ed) for the proton probe on proton damaged silicon (3.6 +/- 0.4) x 10-(15) g/MeV, the proton probe on oxygen damaged silicon (3.90 +/- 0.07) x 10-(15) g/MeV, and the oxygen probe on oxygen damaged silicon (3.65 +/- 0.03) x 10(-14) g/MeV have been obtained.
    IEEE Transactions on Nuclear Science 09/2009; 56(4-56):2457 - 2464. DOI:10.1109/TNS.2009.2023123 · 1.46 Impact Factor
  • J. Gál, G. Kalinka, B. M. Nyako
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    ABSTRACT: In the field of nuclear imaging (PET, Compton camera, etc.) the application of detectors that are position sensitive in all the three dimensions could increase spatial resolution of images by avoiding the parallax error. In the present paper the viability of a three-dimensionally position-sensitive scintillation detector using continuous scintillator crystal is theoretically studied. The feasibility of building such a detector is based on the recognition that both the spatial position and the radiant flux of a point-like isotropic radiation source can be determined by performing flux density measurements at four appropriately selected points of the space. On the basis of this one can construct a position-sensitive scintillation detector where the scintillation crystal is surrounded with four or more photodetectors, supposing that the point of interaction (POI) of the gamma ray within the scintillator could be considered as a point-like isotropic light source. The POI coordinates can then be determined relying on the finding that the ratio of two arbitrary linear combinations of the photodetector responses is equal to the same ratio constructed from the solid angles subtended by the photodetectors as seen from the POI. The results of theoretical calculations describing the relations between the photodetector responses and the spatial coordinates of the POI are presented for three different photodetector–scintillator combinations.
    Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment 08/2009; 607(3):607-615. DOI:10.1016/j.nima.2009.06.020 · 1.32 Impact Factor
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    ABSTRACT: The spectral deterioration of Hamamatsu S5821 silicon photodiodes for ion types and energies frequently used in Ion Beam Analysis was investigated. Focused proton beams with energies 430 keV and 2 MeV were applied to generate radiation damage via an area selective ion implantation in unbiased diodes at room temperature. The variations of spectroscopic features were measured “in situ” by Ion Beam Induced Current (IBIC) method as a function of fluence, within the 109–5 × 1012 ion/cm2 range and diode bias voltages, between 0 and 100 V.An empirical model has been developed to describe the radiation damage. Equations are derived for the variations of the normalized peak position and peak width. The derived empirical equations are physically correct, as far as they account for the superposition of the influence of charge carrier trapping by native and radiation-induced defects and for the effect of charge carrier velocity saturation with electric field strength, as well.
    Nuclear Instruments and Methods in Physics Research Section B Beam Interactions with Materials and Atoms 06/2009; 267:2203-2207. DOI:10.1016/j.nimb.2009.03.053 · 1.19 Impact Factor
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    ABSTRACT: We report on a distributed online coincidence detection implementation that we have recently added to the miniPET-II small animal PET scanner. The implementation uses standard Ethernet and IP multicasting techniques, therefore no architectural changes were necessary to the existing system. For 2D reconstruction the implementation scales with the number of detectors in the system, so it can be used for larger ring configurations, too. The online coincidence detection makes the system suitable for real time imaging applications.
    IEEE Nuclear Science Symposium conference record. Nuclear Science Symposium 01/2009; DOI:10.1109/NSSMIC.2009.5402129
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    ABSTRACT: The DIAMANT-AFRODITE combination has been used to investigate incomplete fusions reactions via the 13C+170Er entrance channel. The intensity of 176Hf (populated via the alpha 3n exit channel) is ~8% of 178W (populated via 5n evaporation) which is ~8 times stronger than that expected from complete fusion. Moreover, 2alphaxn exit channels leading to Yb nuclei are observed with intensities that are ~30-to-40% of 176Hf, for which no yield is expected from complete fusion. A comparison of the intensities from the two-alpha- and one-alpha-gated data is consistent with fragmentation of the 13C beam into (alpha-alpha-alpha-n) which suggests that the population of Yb nuclei results from fusion (or ``massive transfer'') of one the break-up alpha-particles. A campaign of measurements is scheduled for late 2007 with further investigations planned for 2008, including the continuation of the study of superdeformation in 32S.
    05/2008; DOI:10.1063/1.2939348

Publication Stats

284 Citations
119.55 Total Impact Points

Institutions

  • 1994–2013
    • Hungarian Academy of Sciences
      • • MTA Institute of Nuclear Research
      • • Danube Research Institute
      Budapeŝto, Budapest, Hungary
  • 2006
    • University of Debrecen
      • Department of Experimental Physics
      Debreczyn, Hajdú-Bihar, Hungary