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Neutron-capture Studies on ^(235)U and ^(238)U via AMS
A. Wallner,K. Buczak,F. Quinto,P. Steier,T. Belgya,L. Szentmiklosi,M. Bichler,I. Dillmann,F. Kappeler,A. Mengoni 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23
Major nuclear data libraries exhibit some discrepancies for the neutron capture reactions ^(235)U(n,γ) and ^(238)</SUP>U(n,γ) at keV energies. These differences reflect also the scatter of experimental data that are primarily based on time-of-flight measurements (TOF) with detection of prompt γ-rays. We report here on an independent approach for studying such reactions: Neutron activations with subsequent accelerator mass spectrometry (AMS) measurement represent an independent technique, where interference from fission is completely excluded. Activations of natural uranium samples were performed with cold neutrons (Budapest), thermal (Vienna) and with neutrons of 25 and 500 keV (Karlsruhe) for the measurement of ^(235)U(n,γ) and ^(238)U(n,γ). The produced long-lived ^(236)U and the decay product of ^(239)U, ^(239)Pu, respectively, were subsequently counted by AMS at the Vienna Environmental Research Accelerator. This method for measuring the neutron capture cross section has the advantage that the involved systematic uncertainties are in no way correlated with those inherent to the TOF technique. Preliminary data for these neutron energies indicate good agreement with evaluations and seem to support in the keV energy range the reported lower cross-section values for both capture reactions.
Neutron Capture on <SUP>209</SUP>Bi: Determination of the Production Ratio of ^(210m)Bi/^(210g)Bi
F. Gunsing,E. Berthoumieux,A. Borella,T. Belgya,L. Szentmiklosi,P. Schillebeeckx,J. C. Drohe,R. Wynants,N. Colonna,S. Marrone,G. Tagliente,R. Terlizzi,C. Domingo-pardo,J. Tain,T. Martinez,C. Massimi,P 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23
Neutron capture on ^(209)Bi produces either an isomeric state ^(210m)Bi with a half life of 3×10^6 years, or the ground state ^(210g)Bi which decays with a half life of 5 days to the alpha emitter ^(210)Po. Therefore the neutron capture cross section ratio ^(209)Bi(n,γ) ^(210m)^(Bi)/^(210g)Bi plays an important role in predicting the short- and long-term radio-toxicity produced by ^(209)Bi under neutron irradiation. This ratio is dependent on the neutron energy. We have measured this ratio for cold neutrons at the cold neutron beam facility of the Budapest Neutron Centre by observing the population of the ground- and the metastable state using high resolution gamma-ray spectroscopy. The same technique hasbeen used at the pulsed white neutron source GELINA of the IRMM, Geel in combination with the neutron time-of-flight technique. Results for the neutron-energy dependent branching ratio will be presented. In addition we performed simulations using a statistical decay code.
Rudolf Gesztelyi,Zita Wachal,Bela Juhasz,Mariann Bombicz,Evelin Csepanyi,Krisztian Pak,Judit Zsuga,Csaba Papp,Zoltan Galajda,Klara Branzaniuc,Robert Porszasz,Andras Jozsef Szentmiklosi,Arpad Tosaki,Zs 대한약학회 2013 Archives of Pharmacal Research Vol.36 No.3
A1 adenosine receptors (A1 receptors) arewidely expressed in mammalian tissues; therefore attainingproper tissue selectivity is a cornerstone of drug development. The fact that partial agonists chiefly act on tissueswith great receptor reserve can be exploited to achieve anappropriate degree of tissue selectivity. To the best of ourknowledge, the A1 receptor reserve has not been yetquantified for the atrial contractility. A1 receptor reservewas determined for the direct negative inotropic effect ofthree A1 receptor full agonists (NECA, CPA and CHA) inisolated, paced guinea pig left atria, with the use of FSCPX, an irreversible A1 receptor antagonist. FSCPXcaused an apparently pure dextral displacement of theconcentration–response curves of A1 receptor agonists. Accordingly, the atrial A1 receptor function converging toinotropy showed a considerably great, approximately80–92 % of receptor reserve for a near maximal (about91–96 %) effect, which is greater than historical atrial A1receptor reserve data for any effects other than inotropy. Consequently, the guinea pig atrial contractility is verysensitive to A1 receptor stimulation. Thus, it is worthwhileconsidering that even partial A1 receptor agonists, given inany indication, might decrease the atrial contractile force,as an undesirable side effect, in humans.