Showing papers by "National Nuclear Energy Commission published in 1968"
TL;DR: In this article, the pion and conspirator residues and trajectories were found to reproduce with accuracy the forward peak in the high-energy differential cross-section of the PDE.
22 citations
TL;DR: In this paper, the Stokes shift, activation energy of thermal quenching and luminous efficiency of lead silicate glasses were investigated at liquid nitrogen temperature, and the results confirmed the similarity of emitting centers in glasses and in crystals.
Abstract: Absorption spectra and luminescence spectra of lead silicate glasses excited by the 2537 A Hg line have been studied at liquid nitrogen temperature. The samples studied were three lead glasses of the system K 2 OPbOSiO 2 having a PbO content of 1.5, 13.5 and 28.5 mol%, PbCl 2 and BaCl 2 (Pb). The glassy samples having 1.5 and 13.5 PbO mol% show three emission maxima at about 2.7, 3.4 and 3.9 eV respectively; BaCl 2 (Pb) at 2.78 3.50 and 3.94eV. PbCl 2 and the glass containing 28.5 mol% of PbO show a single luminescence maximum at 2.78 and 2.54 eV respectively. The relative efficiency (η) and the activation energy of thermal quenching ( E s ) have been measured. The Stokes shift (Δe) has been evaluated from emission and absorption data. The relation between, η, E s and Δe is discussed. Experimental results suggest that: a) Emission of lead silicate glasses is not related to Pb 0 atoms but to Pb ++ ion levels; b) The visible emission, both in vitreous and in crystalline compounds, is related to the 3 P 0 → 1 S 0 transition; c) The thermal dependence curves of luminescence efficiency agree with a localized center both in glass and in crystals; d) The Stokes shift, activation energy of thermal quenching and the luminous efficiency can be related by means of multiphonon theory. The results confirm the similarity of emitting centers in glasses and in crystals.
17 citations
TL;DR: In this paper, the apparatus and the experimental method used for the measurements of the single-π+ photoproduction by linearly polarized γ rays are described and the present results on the asymmetry ratioA (θ) are summaized.
Abstract: The apparatus and the experimental method used for the measurements of the single-π+ photoproduction by linearly polarized γ rays are described. The present results on the asymmetry ratioA (θ) are summaized. The range covered by our results is θ=(30÷145)o (c.m.) andEγ=(200÷450) MeV.
16 citations
TL;DR: In this paper, some results on the corrosion of silver in various mixtures of fused alkali metal nitrates, at different temperatures, are reported and compared with predictions drawn from the appropriate E /pO 2− diagrams.
16 citations
TL;DR: In this paper, a method to distinguish direction (right ⇄ left, up ⇄ down) of cosmic rays is proposed, using double time-of-flight measurements between two 100 × 100 × 2 cm3 scintillation counters.
14 citations
TL;DR: In this paper, a theoretical account of the wall effect in BF3 proportional counters is given, from the length distributions relative to α and lithium fragments and from approximate energy-range relations.
12 citations
10 citations
9 citations
TL;DR: In this article, the single-particle motion of electrons or positrons in storage rings is studied, giving special attention to the effects determining the beam size in general magnetic structures.
9 citations
8 citations
TL;DR: The results obtained by application of the Monte Carlo method to the skyshine study are described in this article, where the effects of shields over the intensity and energy distribution of diffused neutrons are also studied.
TL;DR: In this article, the authors studied the behavior of ω residue functions in pion photoproduction and showed that they have no zeros att≈−0.15 (GeV/c)2; this is in striking contradiction with the usual explanation of the crossover phenomena.
Abstract: We have studied the behaviour of the ω residue functions in pion photoproduction. We show that they have no zeros att≏−0.15 (GeV/c)2; this is in striking contradiction with the usual explanation of the cross-over phenomena. The behaviour of the ω trajectory near the wrong signature nonsense point α=0 has also been investigated. The usual theory of the dip seems to work well and suggests that unlike the ρ, the ω trajectory is nonsense-choosing.
TL;DR: A method to derive the so-called mass formulae, based on analyticity alone, is presented in this paper, where the behavior of the residue functions is also studied; using the factorization theorem the Toller pole is reconstructed.
31 Oct 1968
TL;DR: In this paper, quasi-elastic electron scattering on nucleons bound in light nuclei is considered using the electron-nucleon interaction of McVoy and Van Hove.
Abstract: Quasi-elastic electron scattering on nucleons bound in light nuclei is considered using the electron-nucleon interaction of McVoy and Van Hove. The shell, model with the harmonic-oscillator potential is assumed to describe the bound nucleons in the initial state. The outgoing nucleon is represented by a plane wave and the probability of the nucleon reabsorption is taken into account by means of a reduction factor. Comparison of the quasi-elastic scattering contribution with the inelastic, experimental cross-section for4He,12C and16O is presented. The importance of possible effects of short-range nucleon-nucleon correlations is discussed.
TL;DR: In this article, it was shown that the virtual proton Compton contribution on the wide angle bremsstrahlung may change appreciably the QED predictions, when the intermediate lepton is far off its mass shell.
TL;DR: By examining typical experimental requirements, a new correlation unit is shown that for optimum efficiency the unit should produce any logical function of n binary variables, in a time not much longer than that required for usual coincidence-anticoincidence operations.
TL;DR: In this paper, the quasi-particle second Tamm-Dancoff (QSTD) theory is applied to the study of even-parity states of even tin isotopes, and compared with the quasiparticle TammDan-Dan-coff theory.
Abstract: The quasi-particle second Tamm-Dancoff (QSTD) theory is applied to the study of even-parity states of even tin isotopes, and compared with the quasi-particle Tamm-Dancoff (QTD) theory. Numerical computations were performed with several Gaussian andP2 residual interaction potentials. In contrast to our previous results with a delta force, here our reasonable finite-range forces permit accounting for the 0+ states as well as for the 2+ and 4+ states. Four quasi-particle correlations are included in the ground state. The spurious states of the nucleon number operator are projected out. While the first excited 21+ and 41+ states are generally of almost pure two-quasi-particle character, the first excited 0+ state is quite of the 2qp–4qp mixed type. TheE2-transition probabilities andQ2, the quadrupole moments of the 21+-states are calculated and discussed. The QSTD values ofQ2 can be quite large because of the most important contributions of the mixed 2qp–4qp terms. For one of our Gaussian forcesQ2 (A=116)=+ 0.15 b, a value lying within the limits of the experimental errors. The theory is based on the spherical-shell model.
TL;DR: In this article, the cross-section for single and double charge exchange nuclear reactions with pions for 1p-shell nuclei was calculated using the Glauber method, and the results were obtained for the reactions of pions of (80÷200) MeV by boron (π+ +11B → π0 +11C) and lithium (π + +7Li → ρ− +7B).
Abstract: The cross-section for single and double charge-exchange nuclear reactions with pions for 1p-shell nuclei is calculated using the Glauber method. The results are obtained for the reactions of pions of (80÷200) MeV by boron (π+ +11B → π0 +11C) and lithium (π+ +7Li → π− +7B).
TL;DR: In this article, the quasi-particle second Tamm-Dancoff (QSTD) theory is extended to include two-and four-proton quasiparticle (qp) excitations.
Abstract: The quasi-particle second Tamm-Dancoff (QSTD) microscopic theory described in previous publications is extended to include two- and four-proton quasi-particle (qp) and mixed two-proton-two-neutron qp excitations. The formalism is appropriate to describe spectra of « vibrational » spherical nuclei with unfilled shells of both neutrons and protons. Variants of this theory are described in which the microscopic two-qp QTD « phonons » are employed in the construction of the basis of a modified QSTD Hilbert space. Formulas are given for the electromagnetic moments and transition matrix elements of the nuclear states. The programmes are discussed of our current numerical applications to the analysis of the spectra of114Cd and of the even Ge isotopes.
01 Jan 1968
TL;DR: In this paper, the authors investigated the dynamic response of a coolant channel due to sharp variations of inlet temperature, power generated within the fuel and fluid velocity, and the analogy of the solutions is shown.
TL;DR: In this article, the authors describe a method used to measure the emittance of the beam from a 10 MeV microtron in operation at Laboratori Nazionali di Frascati.
TL;DR: Two methods for analog to digital conversion based on the digital “prevision” of the incoming pulse amplitude are proposed and analyzed in order to obtain a good speed performance and a very good differential linearity.
TL;DR: In this article, a method for obtaining a sum rule for the pion electromagnetic form factor is proposed, which gives Fπ(k 2)∼F 1v(k2).
Abstract: A method for obtaining a sum rule for the pion electromagnetic form factor is proposed. Numerical evaluations giveFπ(k2)∼F1v(k2). Some results about residues of the pion trajectory att=mπ2 for everyk2 are also obtained in the evasive and in the conspiratorial case.
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TL;DR: The linear chain described in this article can be used as a fast linear gate, allowing further processing at high repetition rates (up to 20 Mc/sec), or it can be employed as a gated integrator with a short dead time.