scholarly journals The Cross Section for the 16O(g,n)15O Reaction

1957 ◽  
Vol 10 (2) ◽  
pp. 326 ◽  
Author(s):  
BM Spicer
Keyword(s):  
Fine Structure ◽  
Cross Section ◽  
Present Note ◽  
Yield Curve ◽  
Giant Resonance ◽  
Yield Curves ◽  
Single Level ◽  
The Cross

There have been a number of attempts to account for the nature of the giant resonance of nuclear photodisintegration (e.g. Goldhaber and Teller 1948; Steinwedel and Jensen 1950; Wilkinson 1955; and others). Levinger and Bethe (1950) believe that a " many-level" theory of the giant resonance is more satisfactory than a single-level theory. The existence of fine structure in the yield curve of the 16O(?,11,) reaction at energies near the giant resonance (Penfold and Spicer 1955) supports this conclusion. The purpose of the present note is to show that the existence of structure within the giant resonance may be demonstrated more simply than by the tedious study of fine structure in yield curves.

scholarly journals The Photonuclear Giant Resonance in Silicon?28

1965 ◽  
Vol 18 (1) ◽  
pp. 15 ◽  
Author(s):  
AW Parker ◽  
RR Whitehead ◽  
GG Shute
Keyword(s):  
Excited State ◽  
Ground State ◽  
Yield Curve ◽  
Giant Resonance ◽  
Fair Agreement ◽  
Yield Curves ◽  
First Excited State ◽  
Reaction 27Al

The 90� yields of ?-rays from the reaction 27Al(p,?)28Si have been obtained at intervals of 40 keV for proton energies between 8�02 and 10�42 MeV. The ground state y-ray (?o) and the first excited state y-ray (?l) were adequately resolved. The two yield curves show considerable structure and, with the present resolution, there is a strong one-way correspondence between them. The gross structure of the ?o yield curve is compared with data from the 28Si(?,n)27Si reaction and fair agreement is found.

scholarly journals Fine structure of plastids during androgenesis in Hordeum vulgare L.

2014 ◽  
Vol 49 (3) ◽  
pp. 205-210 ◽  
Author(s):  
Fortunat Młodzianowski ◽  
Krystyna Idzikowska
Keyword(s):  
Fine Structure ◽  
Hordeum Vulgare ◽  
Cross Section ◽  
Egg Cell ◽  
Hordeum Vulgare L ◽  
Starch Grains ◽  
Ultrathin Sections ◽  
The Cross ◽  
Plastid Ribosomes ◽  
Fertilized Egg

The fine structure of plastids was studied in the course of androgenesis in in the pollen of <em>Hordeum vulgare</em> L. It was found that these organelles occur in all stages of androgenesis. Their structure was simple and was frequently manifested on the cross section only by the presence of the envelope and matrix of different degree of density. Single thylakoids, nucleoid-like regions and starch grains were, however, also noted. The structure of plastids in embryoids formed from microspores of barley was compared with embryos developed from fertilized egg cell, and we did not found any fundamental differences between them. However, only plastid ribosomes were difficult to identify on ultrathin sections in embryoids and in the embryos.

scholarly journals The Dynamic Collective Model Interpretation of the Photoneutron Cross Section of 181Ta

1973 ◽  
Vol 26 (5) ◽  
pp. 585 ◽  
Author(s):  
RS Hicks ◽  
BM Spicer
Keyword(s):  
Fine Structure ◽  
Excitation Energy ◽  
Cross Section ◽  
Neutron Detection ◽  
Collective Model ◽  
High Excitation ◽  
Absolute Value ◽  
Model Interpretation ◽  
Quadrupole Resonance ◽  
The Cross

The cross section for photoneutron production in 181Ta has been measured from threshold to 28� 8 MeV using bremsstrahlung and direct neutron detection. Integrated between these limits, the absolute value of the cross section has been determined to be 2 '47 �O' 35 MeV. b. An examination of the cross section variation with excitation energy reveals the existence of the giant quadrupole resonance lying on the high excitation edge of the dipole peak. This provides additional evidence for the validity of the dynamic collective model. The present data do not support the existence of extensive fine structure below 17 MeV, as proposed by Ishkhanov et al. (1969).

scholarly journals Interference Between Levels in Nuclear Reactions

1967 ◽  
Vol 20 (3) ◽  
pp. 341 ◽  
Author(s):  
FC Barker
Keyword(s):  
Nuclear Reaction ◽  
Cross Section ◽  
Nuclear Reactions ◽  
Matrix Theory ◽  
R Matrix ◽  
Single Level ◽  
The Cross

In this note we consider the cross section for a nuclear reaction in which one of the product nuclei is unstable, with two or more levels contributing to its decay. Previously a formula had been derived from R-matrix theory for the case where contributions come from only a single level of the nucleus with a given spin and parity.

FINE STRUCTURE IN THE O16(γ, n)O15 YIELD CURVE

1959 ◽  
Vol 37 (12) ◽  
pp. 1357-1364 ◽  
Author(s):  
H. King ◽  
L. Katz
Keyword(s):  
Fine Structure ◽  
Cross Section ◽  
Absorption Cross Section ◽  
Yield Curve ◽  
Photon Absorption ◽  
Experimental Techniques ◽  
Absorption Cross ◽  
Good Agreement ◽  
Near Threshold

Fine structure in the OI6(γ, n)O15 yield curve near threshold was examined using improved experimental techniques. Breaks were observed at threshold, 15.85, 16.14, 16.45, 16.74, 16.88, 17.05, 17.15, and 17.21 Mev. These energies are established to within ± 0.04 Mev. The integrated photon absorption cross section in these breaks resulting in (γ, n) reactions was found to be 0.47 ± 0.11 Mev-mb. Our results are in good agreement with the measurements of other workers.

CUMULATIVE YIELDS OF THE HEAVY FRAGMENTS IN THE THERMAL-NEUTRON FISSION OF 241Pu

1964 ◽  
Vol 42 (11) ◽  
pp. 2063-2079 ◽  
Author(s):  
H. Farrar ◽  
W. B. Clarke ◽  
H. G. Thode ◽  
R. H. Tomlinson
Keyword(s):  
Fine Structure ◽  
Thermal Neutron ◽  
Isotope Dilution ◽  
Yield Curve ◽  
Mass Spectrometric ◽  
Mass Yield ◽  
General Shape ◽  
Neutron Fission ◽  
Yield Curves ◽  
Thermal Neutron Fission

The relative yields of isotopes of xenon, cesium, barium, cerium, neodymium, and samarium formed by the thermal neutron fission of 241Pu have been obtained by mass spectrometric methods. The relative yields of the elements were normalized by means of the isotope dilution and isobaric techniques, and absolute cumulative yields were determined by summing the relative yields to 100%. The curve obtained for 241Pu is compared with other mass–yield curves. The general shape of this mass–yield curve is similar to that for 239Pu; yet the fine structure shows greater similarity to that for 235U thermal-neutron fission.

29.—Fine-structure in the Mass-yield Curve for Binary Fission—A Possible Secondary Effect

1974 ◽  
Vol 71 (4) ◽  
pp. 333-336
Author(s):  
N. Feather
Keyword(s):  
Fine Structure ◽  
Short Range ◽  
Mass Number ◽  
Yield Curve ◽  
Neutron Emission ◽  
Secondary Effect ◽  
Mass Yield ◽  
Yield Curves ◽  
Number Range ◽  
Α Particles

SynopsisThe recent suggestion (Feather 1974) that the short-range α-particles of fission are emitted predominantly from post-neutron-emission fragments in the mass-number range 140 to 145 is shown to have implications in relation to the fine-structure of the mass-yield curve. An examination of the mass-yield curves of Unik et al. (1973) discloses, in many of them, a fine-structure feature of the type predicted.

PHOTONEUTRON REACTIONS IN G12 AND O16

1961 ◽  
Vol 39 (5) ◽  
pp. 643-656 ◽  
Author(s):  
J. P. Roalsvig ◽  
Ishwar C. Gupta ◽  
R. N. H. Haslam
Keyword(s):  
Cross Section ◽  
Yield Curve ◽  
Bremsstrahlung Energy ◽  
The Cross ◽  
Section Curve ◽  
Maximum Bremsstrahlung Energy ◽  
The University

Absolute yields of the reactions C12(γ,n)C11 and O16(γ,n)O15 have been determined at 22-Mev maximum bremsstrahlung energy using the University of Saskatchewan 24-Mev betatron. For the reaction C12(γ,n)C11 a yield curve from threshold to 24 Mev has been obtained and the cross-section curve for the reaction computed. A thorough comparison with other results has been made.

Fine structure of the cross section of contact inelastic scattering of an X-ray photon by an atom

2008 ◽  
Vol 105 (1) ◽  
pp. 1-6
Author(s):  
A. N. Khoperskiĭ ◽  
A. M. Nadolinskiĭ ◽  
A. S. Kasprzhitskiĭ
Keyword(s):  
Fine Structure ◽  
Inelastic Scattering ◽  
Cross Section ◽  
X Ray ◽  
The Cross

scholarly journals The Photoneutron Cross Section of Natural Osmium

1977 ◽  
Vol 30 (6) ◽  
pp. 677 ◽  
Author(s):  
Su Su ◽  
RH Sambell ◽  
EG Muirhead ◽  
BM Spicer
Keyword(s):  
Cross Section ◽  
Giant Dipole Resonance ◽  
Yield Data ◽  
Yield Curves ◽  
Dipole Resonance ◽  
Theoretical Predictions ◽  
Show Evidence ◽  
Bremsstrahlung Yield ◽  
The Absolute ◽  
The Cross

The absolute (y, xn) cross section of natural osmium is extracted from bremsstrahlung yield curves measured from the lowest (y, n) threshold of osmium isotopes up to 28 MeV in energy steps of 0�2 MeV. The VBPL method of Bramanis et al. (1972) has been used to unfold the cross section from bremsstrahlung yield data. The results do not show evidence of significant amounts of splitting of the giant dipole resonance, as might be expected from the theoretical predictions of Sedlmayr et al. (1974), but at the same time are not inconsistent with their general features.

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