An analysis of the total neutron cross section of 89Y between 0.3 and 9.0 MeV

A measurement of the total neutron cross section of 89Y from 0.3 MeV to 9.0 MeV is presented. Values for the nuclear level density and average neutron total width of the levels in 90Y are deduced for excitation energies of 7.26, 7.86 and 9.61 MeV. The measurement is compared with the theoretical cross section derived from the generalised optical potential of Wilmore and Hodgson (1964) and also with an R-matrix calculation of Ramavataram et al. (1975). Fluctuations are observed in the cross section below 1.5 MeV. An analysis of the fluctuations indicates they can be explained by fluctuations in the widths and spacings of the levels in 90Y.

[1]  H. W. Newson,et al.  s- and p-wave neutron spectroscopy. Xe. Intermediate structure in 90Y and the generalized R-matrix theory , 1976 .

[2]  H. Vonach,et al.  Level density parameters for the back-shifted fermi gas model in the mass range 40 < A < 250 , 1973 .

[3]  G. I. Crawford,et al.  A facility for fast neutron time of flight experiments , 1973 .

[4]  B. Goulard,et al.  A generalized r-matrix interpretation of the 89Y + n total cross section at low incident energies , 1973 .

[5]  J. E. Monahan,et al.  Possible resonance structure in the elastic scattering of neutrons by Y near En = 1 MeV , 1973 .

[6]  G. I. Crawford,et al.  Neutron total cross section of 31P between 0.75 MeV and 9.00 MeV , 1972 .

[7]  H. W. Newson,et al.  s- AND p-WAVE NEUTRON SPECTROSCOPY. PART Xa. INTERMEDIATE STRUCTURE, 2p-- 1h STATES. , 1972 .

[8]  J. Gilat.  Analytical Approximation of the Combinatorial Calculation of Nuclear Level Densities , 1970 .

[9]  J. R. Grover,et al.  SHELL-MODEL COMBINATORIAL CALCULATIONS OF NUCLEAR LEVEL DENSITIES. , 1969 .

[10]  K. Eberhard,et al.  An explicit expression for the average total width of compound levels , 1969 .

[11]  Robert W. Brown.  Comparison of the Scattering of Electrons and Positrons from Protons. , 1968 .

[12]  H. Barschall,et al.  FLUCTUATIONS IN NEUTRON TOTAL CROSS SECTIONS. , 1967 .

[13]  T. Mayer-Kuckuk,et al.  Fluctuations in nuclear reactions. , 1966, Annual review of nuclear science.

[14]  A. G. W. Cameron,et al.  A COMPOSITE NUCLEAR-LEVEL DENSITY FORMULA WITH SHELL CORRECTIONS , 1965 .

[15]  P. Hodgson,et al.  The calculation of neutron cross-sections from optical potentials , 1964 .

[16]  T. D. Newton.  Shell Effects on the Spacing of Nuclear Levels , 1956 .