Rapor

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Browsing Rapor by Publisher "T.A.E.C., Çekmece Nuclear Research Center"

Now showing 1 - 13 of 13
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    A home-made neutron crystal spectrometer for research and training
    (T.A.E.C., Çekmece Nuclear Research Center, 1965-11) Akyüz, R. Ö.; Cansoy, Ç.; Domaniç, F.; TAEK-ÇNAEM
    In order to make experimental research in the field of low energy nuclear physics, a crystal neutron spectrometer is constructed in ÇNAEM. The energy range is between 0,025 - 6 eV. The available monochromator single crystals are Be, NaCl, (CaCO3), Pb. The minimum precise rotation of spectrometer is 1 minute of arc in Bragg angle. Two Soller type collimators, one from reactor to crystal and the other from sample to counter, are used. The net angular divergence is approximately 5 minutes of arc. Counting system consists of two channels, one of which is used for monitoring the reactor. Counter tubes are B10 enriched BF3 proportional counters. The main problem in construction was, to design and give precise movement to the heavy crystal shielding.
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    Crystal spectrometer measurement of Çekmece TR-1 thermal neutron spectrum
    (T.A.E.C., Çekmece Nuclear Research Center, 1964) Domaniç, F.; TAEK-ÇNAEM; Akyüz, Ö.; Bayvas, F.; Cansoy, Ç.
    The Thermal Neutron Spectrum of Çekmece TR-1 was measured by using a double drystal spectrometer and NaCf crystal with its (200) plane as monochromator. The neutron energy which corresponds to the maximum of thermal flux distribution was found to be E(0) = 0,0595 ev. Assuming that the flux distribution to be Maxwellian an attempt was made to analyze the measured data to evaluate the effective neutron temperature in the beam hole. Because the theoretical expressions given in the latest publications are found to be unsatisfactory in representing neutron reflectivity for slow neutrons, an experiment was carried out to determine the reflectivity in dependence of neutron energy, the results of the experiment showed that the reflectivity in proportional to E-0,45. By using this empirical relation the effective neutron temperature was found to be ≈ 337°K.
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    Inversion of the cyanide group into iso-cyanide under gamma irradiation
    (T.A.E.C., Çekmece Nuclear Research Center, 1965-10) Erben, M. Talat; Ünseren, Envare; Seber, Nurten; TAEK-ÇNAEM
    Infrared spectrophotometric evidence indicates that gamma irradiation of the nitriles causes partial inversion of the cyanide group into iso-cyanide according to the following mechanism: In the gamma flux, some of the cyanide groups are detached from the nitrile as cyan free radicals and, owing to their resonance-hybrid structure, .C=N - <-> - C=N., two distinct recombination processes take place leading partly to the usual cyanide and partly to the iso-cyanide, respectively. From a comparison of the optical densities at the characteristic frequency of the iso-cyanide absorption band in irradiated methacrylonitrile and ethyl iso-cyanide it is concluded that at least 20% of the cyanide groups were transformed into iso-cyanide in a specific sample of methacrylonitrile irradiated to a total dose of 0.1 megarads.
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    Localiztion properties of the unitary representations of the poincare group in field theory
    (T.A.E.C., Çekmece Nuclear Research Center, 1968-02) Gürsey, Feza; TAEK-ÇNAEM
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    On second order correction to the average extrapolation length
    (T.A.E.C., Çekmece Nuclear Research Center, 1963) İnönü, E.; TAEK-ÇNAEM
    A first-order expression for the average extrapolation length in bare thermal reactors was given previously on the basis, of a many-group calculation. C. Yalçın extended this calculation to second order and obtained a complicated correction term which does not seem easy to apply. His results are analyzed and simplified here by considering the limit for continuous slowing down. It is shown that the second order correction is of the order of d/R, where is the first order average extrapolation length and R is a length which characterizes the size of the reactor.
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    On the Özemre's approach to the problem of reflected media
    (T.A.E.C., Çekmece Nuclear Research Center, 1964-12) TAEK-ÇNAEM; Ertek, Çetin
    It is shown that the global method proposed by Özemre for reflected media is based on a tacit assumption which can not hold in general but which turns out to be a fair approximation. The comparison of this method with the two group and the modified one group theories suggests that it occupies a place between them.
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    On the two dimensional solutions for an elastic semi-infinite medium with couple stress
    (T.A.E.C., Çekmece Nuclear Research Center, 1965-04) Şuhubi, E. S.; TAEK-ÇNAEM
    The governing differential equations for an elastic medium with couple stress are solved for a semi-infinite region in static plane deformation by using Fourier transforms. The formal solution can be utilized in a large class of boundary value problems concerning the region in question. For an arbitrary distribution of surface tractions and moments explicit results are given and the solution is obtained for the uniformly distributed surface tractions and moments.
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    Parameters for the first and second neutron resonance in 149 SM
    (T.A.E.C., Çekmece Nuclear Research Center, 1968-06) Akyüz, Ö. R.; Cansoy, Ç.; Domaniç, F.; Örgeevren, Y.; TAEK-ÇNAEM
    The total neutron cross section of natural samarium has been measured in the energy range from 0,06 to 1 eV with a crystal spectrometer using the Be(1011) and Be(1231) crystal planes as monochromators.In this region two resonances due to 149Sm are present. After correction for second order contamination caused by the monochromator, Doppler corrections have been applied to both resonances. Corrections for spectrometer resolution were needed only for the second resonance. Both resonances were fitted separately to the Breit-Wigner single-level formula by the method of least squares. The analysis gives the parameters of the resonances as follows: E(o) = 0.0973±0.0012 eV, Q(o) - 18348±376 b, r = 0.0635±0.0013 eV,r(n) = (0.0773±0.0025)x10(-3) eV for the first and E(o) = 0.872±0.012 eV, Q(o) = 2948±68 b, r =0.0635±0.0015 eV, r(n) = (0.1114±0.0041)x10 (-3) eV for the second. The statistical weight factor g is taken to be 9/16 for both levels.
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    Reactor kinetics equations according to P1- appoximation
    (T.A.E.C., Çekmece Nuclear Research Center, 1969-12) Gençay, Şarman; TAEK-ÇNAEM
    In this work we deduce the reactor kinetics equations according to P1-approximation developed by A. Y. ÖZEMRE.
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    Recent developments in radiopharmaceuticals
    (T.A.E.C., Çekmece Nuclear Research Center, 1973) Tubis, Manuel; TAEK-ÇNAEM
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    Unified transport theory of two - temperature fully ionized plasmas
    (T.A.E.C., Çekmece Nuclear Research Center, 1968-07) Daybelge, Umur; TAEK-ÇNAEM
    The transport coefficients of a nonisothermal, fully ionized plasma have been determined without any cut-off procedure. The theory is exact in the sense that it is valid not only for large values of the Coulomb logarithms themselves but also for large values of their arguments. The effect of interactions between electrons and plasma oscilations has been incorporated in the theory. External magnetic fields have not been considered.