Sezioni d’urto elastico protone-protone e neutrone-protone
TL;DR: In this paper, the decadimento del Cd109 per cattura elettronica orbitale was riferisce, con respecto to un contatore proporzionale l'intensita delle radiazioni.
Abstract: Si riferisce sul decadimento del Cd109 per cattura elettronica orbitale. Il rapportoP
L
/P
K
tra la probabilita di disintegrazione per catturaL e quella per catturaK viene determinato misurando con un contatore proporzionale l’intensita delle radiazioniLX eKX. Si ottiene:P
L
/P
K
=0,32±0,04. Una conferma di questo risultato viene ottenuta misurando le intensita delle radiazioniKX e γ con uno spettrometro a scintillazione ad un cristallo. Questo metodo fornisce il valore:P
L
/P
K
≊0,29. Utilizzando la teoria di Marshak sul decadimento per cattura elettronica, si ha per l’energia della transizione:E
0=67
−3
+8
keV.
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TL;DR: In this article, cross section data for interactions of nucleons, antinucleons, mesons, K, and mesons ( pi ) are compiled and discussed, and specific features common to particles of different kinds exist.
Abstract: Cross section data for interactions of nucleons, antinucleons, mesons (K), and mesons ( pi ) are compiled and discussed. At high energies, specific features common to particles of different kinds exist. Information on phenomena occurring in the region of very small space-time scales may be obtained. Most of the data is obtained from experiments using accelerators in which large particle- beam densities facilitate precision measurements. Weak neutrino reactions at high energies are discussed. (L.N.N.)
42 citations
TL;DR: In this article, the complex potential for neutrons in an infinite nuclear medium is computed in a perturbation calculation up to the second order, using for the nucleon-nucleon interaction a regular potential which fits the low energy two-body data.
Abstract: The complex potential for neutrons in an infinite nuclear medium is computed in a perturbation calculation up to the second order, using for the nucleon-nucleon interaction a regular potential which fits the low energy two-body data. It is shown that it is possible to fit simultaneously the real and the imaginary part of the optical potential and the binding energy of the nuclear matter at normal density. Some arguments for the convergence of the theory are given.
20 citations
TL;DR: In this paper, the imaginary part of the nuclear optical potential for nucleons is investigated in a semi-quantitative way using harmonic oscillator wave functions for O16 and Ca40.
12 citations
TL;DR: In this article, the elastic scattering of protons by free protons in the emulsion have been found in 1539 metres of track, and the results are compared with other experimental work.
Abstract: Ilford G5 emulsions have been exposed to a 925 mev beam from the Birmingham proton synchroton. Sixty-five examples of the elastic scattering of protons by free protons in the emulsion have been found in 1539 metres of track. After removal of events having azimuthal angles ψ>45° where ψ is the angle between the plane of the two secondary particles and the plane of the emulsion, the remaining 44 events yielded a total elastic cross section of 17±3mb. The angular distribution of all the events shows a strong forward peak in the centre of mass system. The shape of this distribution has been compared with the predictions of a simple optical model and a value of (0·9±0·1) × 10−13 cm has been found for the interaction radius of the proton. The results are compared with other experimental work.
11 citations
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TL;DR: In this article, the total cross sections of over 50 elements were measured in good geometry for 14-Mev neutrons and the deviations from the linear relationship predicted by statistical theory were most pronounced for the heaviest elements.
Abstract: The total cross sections of over 50 elements were measured in good geometry for 14-Mev neutrons. A plot of the square root of the total cross section versus the one-third power of the atomic weight shows deviations from the linear relationship predicted by statistical theory. The deviations are most pronounced for the heaviest elements.
60 citations
TL;DR: In this article, the total cross sections of twelve different elements were measured using the neutron beam from the 184-inch cyclotron operating with deuterons, and the mean energy of detection of the neutrons in this experiment is estimated to be 95 Mev.
Abstract: The total cross sections of twelve different elements were measured using the neutron beam from the 184-inch cyclotron operating with deuterons. Bismuth fission ionization chambers were employed as both monitor and detector in conventional "good geometry" attenuation measurements in the neutron flux emerging from the three-inch diameter collimating port in the 10-foot thick concrete shielding. The mean energy of detection of the neutrons in this experiment is estimated to be 95 Mev.Measurements were also made with a monitor and detector placed inside the concrete shielding where we could obtain an intense neutron flux over a large area. Attenuators of four different elements were placed in front of the detector in a "poor geometry" arrangement so that attenuation was due essentially to inelastic collisions which degrade the neutron energy below the fission threshold. A second detector was placed outside the concrete shielding in the collimated neutron beam in line with the neutron source, absorber, and first detector. Attenuation in it is caused by both inelastic and elastic scattering. By this arrangement the ratio of inelastic to total cross section can be determined directly in one experiment.The nuclear radii as calculated from the observed cross sections using the theory of the transparent nucleus vary as 1.38\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}13}$ A\textonehalf{} cm. In this energy range the ratios of the inelastic to total cross sections are all less than one-half.
49 citations
TL;DR: In the energy region between 200 kv and 600 kv, a strong attractive force of short range acting in addition to the repulsive Coulomb forces between the particles was found to give rise to scattering in excess of the Coulomb prediction, appreciable at 700 kilovolts and very marked at 900 kv.
Abstract: Our measurements of proton-proton scattering during 1936 established the existence of large nuclear forces between protons at close distances, in addition to the usual Coulomb forces These nuclear forces give rise to scattering in excess of the Coulomb prediction, appreciable at 700 kilovolts and very marked at 900 kv In the energy region between 200 kv and 600 kv the amount of scattering to be expected on the basis of attractive nuclear forces is radically different from that to be expected on the hypothesis of repulsive nuclear forces since in the first case a decrease and in the second an increase, with respect to the classical scattering, is predicted We have accordingly extended our measurements to include this energy region, and have obtained results which can only be explained by the assumption of a strong attractive force of short range acting in addition to the repulsive Coulomb forces between the particles The magnitude of the nuclear force required is in approximate quantitative agreement with that deduced from our results of 1936, experimental difficulties due to the low residual energies of the scattered particles, and the very small numbers of counts in some regions of voltage and angle (as low as three percent of the Coulomb prediction) preventing a high precision in these results below 600 kv
48 citations
40 citations
TL;DR: In this paper, a least squares analysis of the transmissions of six thicknesses each of carbon and polyethylene (40 to 85 percent transmissions) yielded, for total cross sections in barns:
Abstract: With deuterons from the electrostatic generator of the Department of Terrestrial Magnetism incident on a tritium-zirconium target, and with the neutrons detected by a terphenylxylene scintillator and photomultiplier, total cross sections of C, H, D, O, and N for 14.10\ifmmode\pm\else\textpm\fi{}0.05 Mev neutrons were measured. The effective neutron energy was evaluated from the kinematics of the $\mathrm{T}(d,n){\mathrm{He}}^{4}$ reaction, the dependence of the reaction's cross section on energy and angle, and the multiple scattering of the deuterons and their rate of energy loss in the target. A least squares analysis of the transmissions of six thicknesses each of carbon and polyethylene (40 to 85 percent transmissions) yielded, for total cross sections $\ensuremath{\sigma}$ in barns: ${\ensuremath{\sigma}}_{\mathrm{C}}=1.279\ifmmode\pm\else\textpm\fi{}0.004$ and ${\ensuremath{\sigma}}_{\mathrm{H}}=0.689\ifmmode\pm\else\textpm\fi{}0.005$. Transmissions of light and heavy water gave ${\ensuremath{\sigma}}_{\mathrm{D}}=0.803\ifmmode\pm\else\textpm\fi{}0.014$ and ${\ensuremath{\sigma}}_{\mathrm{O}}=1.64\ifmmode\pm\else\textpm\fi{}0.04$. Transmission of melamine gave ${\ensuremath{\sigma}}_{\mathrm{N}}=1.7\ifmmode\pm\else\textpm\fi{}0.1$.
39 citations