Search results for "positron"
showing 10 items of 1346 documents
Investigation of Solid-Liquid Phase Transition for Sn-54wt%In Alloy by Positron Anihilation Spectroscopy
1995
The peak coincidence counting rate F(T) was measured for Sn-54wt%In alloy at the temperature range from room temperature to 400°C. It was observed that for both heating and cooling run, F(Τ) parameter changes . in the liquid phase. These changes were related to disintegration of SnII microcrystals. From a simple trapping model the defect disintegration enthalpy, H1,, was calculated. For heating and cooling run, the value of H1 was 0.53 ± 0.03 eV and 0.67 ± 0.07 eV, respectively. For well-annealed and cold rolled samples we find only one component, equal 200 ps, in the lifetime spectrum. PACS numbers: 64.70.Dv, 61.72.Cc, 78.70.Bj.
NODAPA-OH and NODAPA-(NCS)n: Synthesis, 68Ga-radiolabelling and in vitro characterisation of novel versatile bifunctional chelators for molecular ima…
2008
This report concerns synthesis, (68)Ga-radiolabelling and stability data of 1,4,7-triazacyclononane-1,4-diacetic acid-7-p-isothio-cyanatophenyl-acetic acid (NODAPA-NCS), 1,4,7-triazacyclononane-1-acetic acid-4,7-di-p-isothiocyanatophenyl-acetic acid (NODAPA-(NCS)(2)) and 1,4,7-triazacyclononane-1,4-diacetic acid-7-p-hydroxyphenyl-acetic acid (NODAPA-OH), versatile bifunctional chelators with potential for molecular imaging. Protein binding and exemplified conjugation are also reported.
Correlation between Zn vacancies and photoluminescence emission in ZnO films.
2006
Photoluminescence and positron annihilation spectroscopy have been used to characterize and identify vacancy-type defects produced in ZnO films grown on sapphire by metal-organic chemical-vapor deposition. The photoluminescence of the samples in the near band edge region has been studied, paying particular attention to the emission at 370.5 nm (3.346 eV). This emission has been correlated to the concentration of Zn vacancies in the films, which has been determined by positron annihilation spectroscopy. Jesus.Zuniga@uv.es Vicente.Munoz@uv.es
A no-carrier-added 72Se/72As isotope generator
2001
Siinznrary A no-carrier-added 72Se/72As generator has been developed for the isolation of 72As, relevant for eventual application in the syntheses of 72As-labelled radiophamaceuticals. Avoiding the addition of Se carrier and using a thennochromatographic destillation process, no-carrier-added 72As is nearly quantitatively released within 10 min. 72Se remains almost quantitatively (> 99.7%) in solution when a temperature of the separation process of 100°C is applied. Introdiiction Arsenic-72 is a positron emitting isotope with properties which are promising for eventual application in 72As-labelled radiopharmaceuticals. It has n positron emission rate of 88% and positron energies of EP+,,,,~…
Extraction of the Muon Signals Recorded with the Surface Detector of the Pierre Auger Observatory Using Recurrent Neural Networks
2021
The Pierre Auger Observatory, at present the largest cosmic-ray observatory ever built, is instrumented with a ground array of 1600 water-Cherenkov detectors, known as the Surface Detector (SD). The SD samples the secondary particle content (mostly photons, electrons, positrons and muons) of extensive air showers initiated by cosmic rays with energies ranging from $10^{17}~$eV up to more than $10^{20}~$eV. Measuring the independent contribution of the muon component to the total registered signal is crucial to enhance the capability of the Observatory to estimate the mass of the cosmic rays on an event-by-event basis. However, with the current design of the SD, it is difficult to straightfo…
A Monte-Carlo based model of the AX-PET demonstrator and its experimental validation
2013
AX-PET is a novel PET detector based on axially oriented crystals and orthogonal wavelength shifter (WLS) strips, both individually read out by silicon photo-multipliers. Its design decouples sensitivity and spatial resolution, by reducing the parallax error due to the layered arrangement of the crystals. Additionally the granularity of AX-PET enhances the capability to track photons within the detector yielding a large fraction of inter-crystal scatter events. These events, if properly processed, can be included in the reconstruction stage further increasing the sensitivity. Its unique features require dedicated Monte-Carlo simulations, enabling the development of the device, interpreting …
Inclusion of Inter Crystal Scatter data in PET
2012
In PET, as the spatial resolution of the measurement system is increased, multiple interactions of a single photon may be separately measured and such events are often removed from the data used in image reconstruction. While for some PET imaging tasks this effect is unimportant, for primate, brain and high-spatial-resolution imaging where sensitivity is important, such Inter Crystal Scattering (ICS) events may constitute a large fraction of the measured data. On-the-fly list-mode image reconstruction is generally required in order to use all the information provided by ICS. Simulated One-Pass List-mode image reconstruction is used in this investigation to study the inclusion of ICS informa…
Sensitivity recovery for the AX-PET prototype using inter-crystal scattering events
2014
The development of novel detection devices and systems such as the AX-positron emission tomography (PET) demonstrator often introduce or increase the measurement of atypical coincidence events such as inter-crystal scattering (ICS). In more standard systems, ICS events often go undetected and the small measured fraction may be ignored. As the measured quantity of such events in the data increases, so too does the importance of considering them during image reconstruction. Generally, treatment of ICS events will attempt to determine which of the possible candidate lines of response (LoRs) correctly determine the annihilation photon trajectory. However, methods of assessment often have low su…
Measurements of the absolute branching fractions forDs+→ηe+νeandDs+→η′e+νe
2016
By analyzing 482 pb(-1) of e(+)e(-) collision data collected at root s = 4.009 GeV with the BESIII detector at the BEPCII collider, we measure the absolute branching fractions for the semileptonic decays D-s(+) -> eta e(+)nu(e) and D-s(+) -> eta ' e(+)nu(e) to be B(D-s(+) -> eta e(+)nu(e)) = (2.30 +/- 0.31 +/- 0.08)% and B(D-s(+) -> eta ' e(+)nu(e)) = (0.93 +/- 0.30 +/- 0.05)%, respectively, and their ratio B(D-s(+) -> eta ' e(+)nu(e)) / B(D-s(+) -> eta ' e(+)nu(e)) = 0.40 +/- 0.14 +/- 0.02, where the first uncertainties are statistical and the second ones are systematic. The results are in good agreement with previous measurements within uncertainties; they can be used to determine the eta…
Amplitude Analysis of theB±→φK*(892)±Decay
2007
We perform an amplitude analysis of B-+/-->phi(1020)K-*(892)(+/-) decay with a sample of about 384x10(6) B (B) over bar pairs recorded with the BABAR detector. Overall, twelve parameters are measured, including the fractions of longitudinal f(L) and parity-odd transverse f(perpendicular to) amplitudes, branching fraction, strong phases, and six parameters sensitive to CP violation. We use the dependence on the K pi invariant mass of the interference between the J(P)=1(-) and 0(+) K pi components to resolve the discrete ambiguity in the determination of the strong and weak phases. Our measurements of f(L)=0.49 +/- 0.05 +/- 0.03, f(perpendicular to)=0.21 +/- 0.05 +/- 0.02, and the strong phas…