THE PHOTODISINTEGRATION OF NITROGEN

The (γ, p), (γ, pn), (γ, α), (γ, αα) and (γ, αp) reactions in 14N have been studied by passing the X-ray beam from a 23 MeV synchrotron through a Wilson cloud chamber. The range distribution of protons of energy up to 3 MeV shows sharp well-defined peaks at energies of 0.51, 1.63 and 2.92 MeV. These energies correspond closely to the energies of the resonances reported for the 13C(p, γ)14N (ground state) reaction. For these resonances the ratios of the cross sections for the (γ, p) and (p, γ) reactions are in good agreement with the predictions of the principle of detailed balancing. At higher energies the following measurements were made: (i) the (γ, p) process was investigated by measuring the range distribution of the 13C nuclei, (ii) both (γ, p) and (γ, pn) processes were studied by measuring the numbers of events at three different synchrotron peak energies. These measurements showed that both the (γ, p) and (γ, pn) cross sections are small at energies up to 15 MeV and large in neighbourhood of 20 MeV. The estimated values of the integrated cross sections up to 23 MeV for the (γ, p) and the (γ, pn) reactions are both approximately 0.02 MeV barn. The (γ, α), (γ, αα) and (γ, αp) cross sections are each about 0.1 millibarn. The implications of these results are discussed in some detail.

[1]  F. Ajzenberg,et al.  Energy Levels of Light Nuclei. V , 1955 .

[2]  J. Halpern,et al.  Photoneutron Cross Sections in He, N, O, F, Ne, and A , 1954 .

[3]  A. Cameron,et al.  FINE STRUCTURE IN THE C$sup 12$($gamma$,n)C$sup 11$ AND O$sup 16$($gamma$,n)O$sup 1$$sup 5$ , 1954 .

[4]  A. Tollestrup,et al.  GAMMA RADIATION FROM THE REACTION C$sup 13$ (p,*gamma)N$sup 1$$sup 4$ , 1953 .

[5]  M. Gell-Mann,et al.  Consequences of Charge Independence for Nuclear Reactions Involving Photons , 1953 .

[6]  F. K. Goward,et al.  Cross-section for the photodisintegration of carbon into three α-particles , 1953, Proceedings of the Royal Society of London. Series A, Mathematical and physical sciences.

[7]  B. Spicer.  Angular Distribution of Photoprotons from Nitrogen , 1953 .

[8]  H. Johns,et al.  GAMMA–NEUTRON REACTIONS IN O16 AND N14 , 1952 .

[9]  J. Seagrave.  Radiative Capture of Protons by C13 , 1952 .

[10]  A. Cameron,et al.  THE SOLUTION OF X-RAY ACTIVATION CURVES FOR PHOTONUCLEAR CROSS SECTIONS , 1951 .

[11]  E. R. Gaerttner,et al.  THE PHOTODISINTEGRATION OF He$sup 4$ NUCLEI BY X-RAYS FROM A 100-MEV BETATRON , 1951 .

[12]  E. R. Gaerttner.  PHOTONUCLEAR EFFECTS IN CARBON FROM 100-MEV BETATRON X-RAYS , 1951 .

[13]  E. R. Gaerttner,et al.  On the Identification of the Predominant Photo-Nuclear Disintegrations in Nitrogen and Oxygen , 1950 .

[14]  H. Bethe,et al.  Dipole Transitions in the Nuclear Photo-Effect , 1950 .

[15]  E. R. Gaerttner,et al.  Cross Sections for the Photo-Disintegration of Nitrogen and Oxygen Nuclei by 100-Mev Betatron X-rays , 1950 .

[16]  E. R. Gaerttner,et al.  The Photo-Disintegration of Nitrogen at Energies of 20 Mev to 100 Mev , 1950 .