The isotope selectivity of computed tomography (CT) imaging based on nuclear resonance fluorescence (NRF) transmission method using a quasi-monochromatic laser Compton scattering (LCS) gamma-ray beam in the MeV region was demonstrated at the Ultra Violet Synchrotron Orbital Radiation-III (UVSOR-III) Synchrotron Radiation Facility (Institute of Molecular Science, National Institute of Natural Science) for two enriched lead isotope rods (206 Pb and 208 Pb) implanted in an aluminum cylinder. Since these two rods show the same gamma-ray attenuation in atomic processes, it is impossible to differentiate between them using a standard Gamma-CT technique based on atomic attenuation of gamma rays. The LCS gamma-ray beam had a maximum energy of 5.528 MeV and an intensity of approximately 5.5 photons/s/eV at the resonance energy (J π = 1 − at 5.512 MeV in 208 Pb). A lead collimator with a hole diameter of 1 mm was used to define the size of the LCS gamma-ray beam at the CT target. The CT image of the 208 Pb rod was selectively obtained with a 2-mm pixel size resolution, which was determined by the horizontal step size of the CT stage. Index Terms-Computed tomography (CT), isotope distribution, laser Compton scattering (LCS) gamma-ray beam, nuclear resonance fluorescence (NRF). I. INTRODUCTION N ONDESTRUCTIVE assay (NDA) technology, which is used to identify specific isotopes in a substance,
Novel injectable thermoreversible hydrogel compositions with semi-interpenetrating network structure were prepared through the addition of sodium alginate (SA) to poly(N-isopropylacrylamide) (PNIPAM) aqueous solutions. The addition of the hydrophilic alginate strongly improved the stability against syneresis of the 15 wt% PNIPAM hydrogels formed at 37 C from less than 15 min in the absence of alginate to more than 7 days in the presence of 4 wt% SA. Besides the SA concentration, the hydrogel stability depended on the molecular weight and polydispersity of PNIPAM, being lower when a high molecular weight fraction was present. The phase transition temperature (T ph ) of the PNIPAM aqueous solutions decreased with alginate concentration, while the dynamic viscosity and elastic modulus of the hydrogels increased. By decreasing the PNIPAM molecular weight and polydispersity, the dynamic viscosity and elastic modulus of the PNIPAM-alginate hydrogels formed above T ph diminished, while their viscoelastic behavior changed from predominantly elastic to predominantly viscous.
The new facility, Extreme Light Infrastructure – Nuclear
Physics (ELI-NP), is a combined laser-gamma nuclear physics research
facility currently undergoing its final implementation stages in
Măgurele near Bucharest, Romania. It already hosts two
fully-operational 10 PW laser arms and, by 2023, it will also house
a γ-beam system based on laser Compton backscattering,
capable of delivering a high-brilliance, low-energy beam at
E
γ ≲ 19.5 MeV. Owing to this unique laser-gamma
instrumentation combination, several types of experiments will be
possible at ELI-NP, including high precision nuclear resonance
fluorescence (NRF) experiments. In this case, the main γ-beam
detection system for performing NRF studies at ELI-NP is represented
by the ELI Array of DEtectors (ELIADE), featuring eight high-purity
germanium (HPGe) segmented clover detectors. The current work
presents the characteristics of two of the ELIADE detectors,
including their photopeak detection efficiency, energy resolution,
and peak-to-total ratio measured using γ-ray sources, as well
as the timing performance obtained via in-beam measurements. For
these latter detector tests, 130La was populated via the fusion
evaporation reaction 121Sb(12C,3n)130La using a beam
energy of 53 MeV at the Horia Hulubei National Institute of Physics
and Nuclear Engineering (IFIN-HH), also located in
Măgurele. Herein, we report on the results of the ^130La
linear polarization measurements taken using the ELIADE detectors as
Compton polarimeters. The results obtained from the in-beam
experiment were compared to several already published works and we
present new information on the transition multipolarity in
130La.
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