Papers by George Pascovici
Journal of Physics: Conference Series, 2012
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2019
A MICROMEGAS detection amplifier has been incorporated into the design of the TAMU MDM focal plan... more A MICROMEGAS detection amplifier has been incorporated into the design of the TAMU MDM focal plane detector with the purpose of improving the energy resolution and thus, the particle identification. Beam tests showed a factor of 2 improvement over the original design, from 10-12% to 4-6%, for ions with A<40 at E/A around 10-20 MeV.
Thin layer activation techniques at the U-120 cyclotron of Bucharest
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 1994
The Thin Layer Activation (TLA) technique is a nuclear method especially used for different types... more The Thin Layer Activation (TLA) technique is a nuclear method especially used for different types of wear (or corrosion) investigations. Experimental results for selection criteria of nuclear reactions for various tribological studies, using the IPNE U-120 classical variable energy Cyclotron are presented. Measuring methods for the main types of wear phenomena and home made instrumentations dedicated for TLA industrial applications
A miniaturized low-power SiPM-based β detector for the ISOLDE Fast Tapestation
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
Sweeping System for the Cyclotron External Beam
Cyclotron beam pulsing in the microsecond range at large duty cycles
EPJ Web of Conferences, 2015
Correction for neutron damage in AGATA detectors using Pulse Shape Analysis
European Physical Journal A
A versatile low-noise wide-range charge-sensitive preamplifier for HPGe detectors
2012 IEEE Nuclear Science Symposium and Medical Imaging Conference Record (NSS/MIC), 2012
ABSTRACT A fast low-noise hybrid charge-sensitive preamplifier for HPGe detectors, has been desig... more ABSTRACT A fast low-noise hybrid charge-sensitive preamplifier for HPGe detectors, has been designed for the new array detector &quot;GALILEO&quot; under construction at INFN Legnaro National Laboratory (Italy). The preamplifier includes an over-threshold fast-reset circuitry that greatly reduces the dead time due to preamplifier and/or ADC saturation. A I -bit digital output signal is provided in LVDS or CMOS format, whose width yields an indirect precise measurement of the large over-threshold signals. Combining the under- and over-threshold working modes an unprecedented spectroscopic dynamic range is obtained of 105, from 0.1 fC to 10 pC, i.e. from ~2 keY to ISO MeV of equivalent energy in germanium. A fast analogue signal is optionally provided as a trigger for ancillary detectors. The preamplifier is optimized to feature low noise, fast rise time and wide amplitude range when connected to anode detector electrodes. It includes a fast differential buffer for low-noise signal transmission to a remote ADC, with a preset common-mode DC component, that can be adjusted to match the ADC requirement. The rise time, as measured at the test bench, is as fast as 7.5 ns, with a detector capacitance of 23 pF and with a 5m son twisted-pair cable connecting the preamplifier to the ADC. With its input transistor working at 150K the preamplifier features an intrinsic noise of ~90 electrons r.m.s., i.e. ~600eV fwhm in germanium, and a noise slope of 8eV/pF.
The new PGAA facility at the FRM II, Garching: comparison with the PIXE results obtained at the new IBA setup at Cologne
X-Ray Spectrometry, 2005
... IBA setup at Cologne Petra Kud ˇejov ´a, ∗ Thomas Materna, Jan Jolie and George Pascovici .... more ... IBA setup at Cologne Petra Kud ˇejov ´a, ∗ Thomas Materna, Jan Jolie and George Pascovici ... PIXE INSTRUMENT An overview of the setup of the PIXE chamber with some possible positions of the detectors is shown in Fig. ...
Two-phonon character of the lowest electric dipole excitation in 142Nd and in other nuclei near shell closures
Physical Review C, 1998
... This indicates that the harmonicity of the two phonon quadrupole-octupole excitations seems t... more ... This indicates that the harmonicity of the two phonon quadrupole-octupole excitations seems to be a general phenomenon in nuclei near shell closures. ... 10 RA Gatenby, EL Johnson, EM Baum, SW Yates, D. Wang, JR Vanhoy, MT McEllistrem, T. Belgya, B. Faze? ...
Crosstalk properties of 36-fold segmented symmetric hexagonal HPGe detectors
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2009
... hole creation in the n-type Ge material, while the holes are collected at the outer segment c... more ... hole creation in the n-type Ge material, while the holes are collected at the outer segment contacts. ... However, measurements with the new 36-fold segmented detectors show a clear difference between the core energy and ... The effect for the segment-sum energy is shown in Fig. ...
The generalized centroid difference method for picosecond sensitive determination of lifetimes of nuclear excited states using large fast-timing arrays
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2013
ABSTRACT A novel method for direct electronic “fast-timing” lifetime measurements of nuclear exci... more ABSTRACT A novel method for direct electronic “fast-timing” lifetime measurements of nuclear excited states via γ–γ coincidences using an array equipped with N∈N equally shaped very fast high-resolution LaBr3(Ce) scintillator detectors is presented. Analogous to the mirror symmetric centroid difference method, the generalized centroid difference method provides two independent “start” and “stop” time spectra obtained by a superposition of the N(N−1)γ–γ time difference spectra of the N detector fast-timing system. The two fast-timing array time spectra correspond to a forward and reverse gating of a specific γ–γ cascade. Provided that the energy response and the electronic time pick-off of the detectors are almost equal, a mean prompt response difference between start and stop events is calibrated and used as a single correction for lifetime determination. These combined fast-timing arrays mean γ–γ time-walk characteristics can be determined with an accuracy less than 5 ps using a 152Eu γ-ray source. Due to reduction and cancellation of many possible systematic errors, the lifetime determination limit of the method over the total dynamic range is mainly determined by the statistics. The setup of an N=4 detector fast-timing array delivered an absolute time resolving power of 3 ps for 10 000 γ–γ events per total fast timing array start and stop time spectrum. The new method is tested over the total dynamic range by the measurements of known picosecond lifetimes in standard γ-ray sources.
Active reset of digitized preamplifiers for ionizing-radiation sensors
IEEE Transactions on Nuclear Science, 2000
In this paper, we propose a new add-on circuit structure that swiftly desaturates a digitized cha... more In this paper, we propose a new add-on circuit structure that swiftly desaturates a digitized charge preamplifier for ionizing-radiation detectors when an energetic event occurs, or when a burst of piled up events puts it into saturation. The amplitude of the energetic event can even be reconstructed with a time-over-threshold (TOT) measurement of the fast-reset transient. With an analog-to-digital converter
Improved energy resolution of highly segmented HPGe detectors by noise reduction
The European Physical Journal A, 2013
ABSTRACT Built-in redundancies in highly segmented high-purity Ge detectors are exploited to incr... more ABSTRACT Built-in redundancies in highly segmented high-purity Ge detectors are exploited to increase the energy resolution of these semiconductor devices for detection of electromagnetic radiation in the X-ray and γ-ray regime. The information of the two electronically decoupled independent measurements, the cathode and the anode electrodes, provides an improved signal-to-noise ratio through a combination of the individually measured signals performed on an event-by-event basis. The average energy resolution values of the AGATA triple cluster detector for an energy deposition of 60keV was measured to be 1.1 keV (FWHM) for the 36 segments and 1.2 keV for the core. The averaged signals of the core and the segments show an improved resolution value of 0.87 keV which is close to the expected theoretical limit. At higher γ-ray energy the averaging technique allows for an enhanced energy resolution with a FWHM of 2.15keV at 1.3MeV. By means of the position sensitive operation of AGATA a new value for the Fano factor was determined and the noise contributions to the FWHM of a γ-ray peak separated.
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Papers by George Pascovici