Search results for "SAMPLE"
showing 10 items of 2270 documents
Behavior of a trapezoid-based data acquisition system up to 100 kHz and beyond
2016
In this work, we investigated the ability of a high-purity germanium detector connected to a trapezoid-filter-based data acquisition system to reliably record signals in spite of high sample activities. By activating multiple Na$_{2}$CO$_{3}$ samples with different Na content, we were able to deduce efficiency, resolution and dead time of the system used as a function of the sample activity. Based on the results, we were able to find a setting which allows measurements of event rates up to 35~kHz per readout channel with an energy resolution of 0.3\% at the 2754 keV $^{24}$Na line.
MCNP5 modelling of HPGe detectors for efficiency evaluation in gamma-ray spectrometry
2009
A modelling of HPGe detectors was performed through simulation with the MCNP5 Monte Carlo code. The simulation results concerning the values of the main physical parameters of the detector are in most cases different from those provided by the manufacturer. The use of “single-line” sources allows us to suitably modify the parameter values used in the detector model. For a detector model, the simulation assesses the distribution of photopeak and total efficiency for point sources, whereas for extended sources a control volume approach allows us to determine elementary efficiency behaviours. An integration of elementary efficiencies over the entire sample volume allows us to evaluate global e…
A position sensitive β−γ coincidence technique for sample analysis with the upgraded PANDA device
2020
Abstract PANDA (Particles And Non-Destructive Analysis) is measuring system developed for non-destructive analysis of samples for safety, security and safeguards. The capabilities of the PANDA device were expanded by the addition of a thick silicon detector for β particle detection. The upgraded device can now be used for position-sensitive α − γ and β − γ coincidence measurements of various kinds of radioactive samples. The capability of the PANDA device in using the β − γ coincidence technique was tested using a mixed source of 134Cs and 226Ra. In addition, the ability of PANDA to locate nuclides emitting β particles from samples was tested using a combined sample containing a mixed 134Cs…
New results on hyperon decays from NA48
2001
In 1999 the NA48 experiment at CERN had two short data taking periods (8h and 40h) with a high intensity KS beam. Together with the KS mesons a large number of neutral hyperons, e.g. Λ and Ξ0, are produced. During these periods a large sample of Ξ0 decays was collected. About 115,000 events of the decay mode Ξ0 → Λπ0, about 500 of Ξ0 → Λγ, about 400 of Ξ0 → Σ0γ and about 60 events of Ξ0 → Σ+ e have been reconstructed. The status of the analyses of the above decay modes is presented.
The X-ray Facility at LAX in Palermo
1996
A description is given of the X-ray facility installed at LAX (Laboratorio per Sperimentazioni con Radiazioni X), jointly operated in Palermo by the DEAF (Department of Energy and Physics Applications) of the University of Palermo and the IFCAT (Institute of Cosmic Physics and Informatics) of the Italian National Research Council. The X-rays are produced by bombarding a target with energized electrons up to 60 keV. Depending on the material of the target, characteristic fluorescence lines as well as continuous bremsstrahlung is emitted. The X-ray beam has an operational energy range of 0,1–25 keV with a flux of 1010–1012 photons/sr · s; the beam, collimated on a length of 10,5 m, has a diam…
Pulsating B and Be Stars in the Magellanic Clouds
2010
Stellar pulsations in main-sequence B-type stars are driven by the κ-mechanism due to the Fe-group opacity bump. The current models do not predict the presence of instability strips in the B spectral domain at very low metallicities. As the metallicity of the Magellanic Clouds (MC) has been measured to be around Z = 0. 002 for the Small Magellanic Cloud (SMC) and Z = 0. 007 for the Large Magellanic Cloud (LMC), they constitute a very suitable objects to test these predictions. The aim of this work is to investigate the existence of B-type pulsators at low metallicities, searching for short-term periodic variability in a large sample of B and Be stars from the MC with accurately determined f…
Measurement of the branching fraction of and search for a CP -violating asymmetry in η′→π+π−e+e− at BESIII
2021
The rare decay η′ → π+π−e+e− is studied using a sample of 1.3×109 J/ψ events collected with the BESIII detector at BEPCII in 2009 and 2012. The branching fraction is measured with improved precisi ...
Search for the DecayB+→K+νν¯
2005
We search for the rare flavor-changing neutral-current decay ${B}^{+}\ensuremath{\rightarrow}{K}^{+}\ensuremath{\nu}\overline{\ensuremath{\nu}}$ in a data sample of $82\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ collected with the BABAR detector at the PEP-II $B$-factory. Signal events are selected by examining the properties of the system recoiling against either a reconstructed hadronic or semileptonic charged-$B$ decay. Using these two independent samples we obtain a combined limit of $\mathcal{B}({B}^{+}\ensuremath{\rightarrow}{K}^{+}\ensuremath{\nu}\overline{\ensuremath{\nu}})l5.2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}$ at the 90% confidence level. In addition, by…
Does the galaxy correlation length increase with the sample depth?
2001
We have analyzed the behavior of the correlation length, $r_0$, as a function of the sample depth by extracting from the CfA2 redshift survey volume--limited samples out to increasing distances. For a fractal distribution, the value of $r_0$ would increase with the volume occupied by the sample. We find no linear increase for the CfA2 samples of the sort that would be expected if the Universe preserved its small scale fractal character out to the distances considered (60--100$\hmpc$). The results instead show a roughly constant value for $r_0$ as a function of the size of the sample, with small fluctuations due to local inhomogeneities and luminosity segregation. Thus the fractal picture ca…
The Computer Code for Calculations of the Positron Distribution in a Layered Stack Systems
2014
In this paper we present experimental and theoretical studies of the implantation pro le of positrons emitted fromNa radionuclide into layered sample. The measured pro le for the nonsymmetrical, around the positron emitter, stack of aluminium and silver foils was measured using the depth scanning of implantation pro le technique. For the description of the obtained results two theoretical approaches were applied. The rst one was the Monte Carlo simulation using the GEANT4 tool kit. The generated pro le does not reproduce accurately the experimental pro le. We proposed the multiple scattering model based on the fact that a positron due to backscattering can travel as an energetic particle se…