REVIEW OF EVALUATIONS FOR
THE TITANIUM ISOTOPES
INTRODUCTION
Systematic comparison with experimental data from EXFOR was made with the ENDVER package for the following evaluations:
ENDF/B-VII.1 http://www.nndc.bnl.gov/
JEFF-3.1.2 http://www-nds.iaea.org/exfor/endf.htm
JEFF-3.2T http://www.oecd-nea.org/dbdata/jeff-beta/JEFF32T1
JENDL-4.0 http://www-nds.iaea.org/exfor/endf.htm
The comparisons are presented for the natural element, which has the most abundant database of experimental data, although similar plots exist for individual isotopes.
All isotopes of titanium from each library
were processed with the PrePro-2010 codes and additional codes
from the ENDVER package for plotting purposes.
Detailed graphical comparison can be viewed from nTi-0.htm; plot numbers in the text below
refer to this list. The plots in the list can be viewed in the
interactive mode. The plots in the discussion below have been
converted to "gif" for the convenience of the users.
To view the plots interactively it is necessary to download the ZVView code and associate ZVD files with this application.
CROSS SECTIONS
The cross sections are generally in good agreement with measurements. Specific conclusions can be summarised as follows below. In the JEFF-3.2T library some of the isotopes are evaluated only up to 20 MeV, therefore the comparisons above this energy are meaningless.
The total cross
sections from JEFF-3.2T seems to agree best with available
experimental data in the EXFOR database, particularly in the
resonance region, as well as at
higher energies between 6 MeV and
12 MeV.
Considering the scatter in the measured inelastic cross sections data, all
evaluations show fairly good consistency.
Very few measurements exist for the capture
cross section. The strong dip in the cross section below
the first resonance in JEFF-3.2T might be unphysical. It is not
present in the ENDF/B-VII.1 library.
The proton-production cross sections
from all evaluated libraries are much higher than the single
measurement of Hassler (1962), which is old.
The tritium-production cross sections
in ENDF/B-VII.1 and JENDL-4.0 are identical and lower than the
single measurement by Biro (1975). The JEFF-3.2T cross sections
are higher, but with uncertainties that enclose the measurement.
The average cosing of scattering (mu-bar,
reconstructed from the angular distributions) in ENDF/B-VII.1
around 1 MeV follows closely the structure in the measured data,
while all other evaluations predict a smooth behaviour.
ANGULAR DISTRIBUTIONS
At low energies (from
about 0.3 MeV) there are considerable differences between
the evaluation, which gradually decrease as the incident neutron
energy increases (e.g. 1.5 MeV).
At 2 MeV and above the agreement
between the data in the libraries with measured data is quite
good. At energies above 7 MeV one
has to be careful about the interpretation of experimental
measurements due to possible contamination of the elastic
angular distributions with the inelastic contribution.
NEUTRON EMISSION SPECTRA
The angle-integrated neutron emission spectra
in the JEFF-3.2T are in excellent agreement with the measured
data by Schmidt (2006), which span from 7.9 MeV to 14.6
MeV. Good agreement is observed at intermediate energies
(e.g. 10.2 MeV). A few
measurements are available from other authors. Experimental data
at 14.1 MeV are particularly
abundant.
PROTON EMISSION SPECTRA
Angle-integrated proton emission spectrum at
14.1 MeV was measured by Takagi
(2000). The spectrum extracted from JEFF-3.2T is much lower.
Other libraries do not contain spectral information for protons.
ALPHA EMISSION SPECTRA
GAMMA EMISSION SPECTRA
The gamma-emission
spectrum from the radiative capture reaction measured by
Voignier (1992) agrees well with the data from the ENDF/B-VII.1
library, which includes detailed structure from the discrete
gamma lines. The gamma spectrumin the JEFF-3.2T library in the
MeV region is much lower and without detailed structure.
