Description of archived isotopic data
TABLE 1 Adopted Prompt Gamma Rays
This entry summarizes the energies and intensities for the prompt gamma
rays adopted for the radiative capture of thermal neutrons by this isotope.
'Adopted' in this context means the final gamma-ray energies and intensities
assigned to an isotope based on an evaluation of the published data.
It also gives a few quantities that summarize the results. The gamma-ray
energies (Eg) are in keV. The gamma-ray intensities (Ig) are per 100
neutron captures (or %). Sn is the neutron binding energy (in keV) for the
product nucleus.
The first line is a short title. Then comes the number of adopted gamma
rays and several sums involving Eg, Ig, or their product. The sum of Eg*Ig
is divided by Sn to see if all of the energy available in the reaction is
accounted for in the adopted data. The sums of the gamma rays known to have
been emitted from the capture state or known to have decayed to the ground
state are also given and should be 100% if the data set is complete and if
there are few internal conversion electrons.
The adopted gamma-ray results are listed with one gamma ray per line.
In addition to the gamma ray's energy and intensity, the energies of the
upper and lower levels (if known) for that gamma-ray transition are also
given.
TABLE 2 Comments on Adopted Data
This text describes the data sets adopted and gives additional comments
on the data for the neutron-capture reaction with this isotope. Complete
references are given below under REFERENCES. Often a comment is given on the
quality of the adopted energies and intensities.
TABLE 3 Comparisons of Prompt Gamma-Ray Energies and Intensities
After a one-line title, there first is a quick summary of the input data
for the product nucleus with the neutron binding energy (Sn), the mass
(in amu) of the product nucleus used to get the recoil energy, and the
energy levels (keV) in the product nucleus. The number of data sets entered
and compared is given followed by the code for each of these data sets in
the "Nuclear Science References" (NSR) format (e.g., 96Be53). Complete
references are given at the end under REFERENCES.
The set (or sets) of data adopted for the energies and for the
intensities of the gamma rays are then given. Adopted sets are identified
by their order (1 through 5) and their NSR code. If more than one set is
adopted, there is a weighting factor for each set. (Note that if one set is
weighted more than another set, then a small fraction of the less weighted
set will be averaged, with the lower weight, to get the final adopted
value.) Data set 6 always refers to the set of gamma rays whose energies have been
calculated by subtracting the recoil energy from the difference in the level
energies for the transition. The number of gamma rays from the adopted data
with non-zero values of Eg and Ig are given along with the number of entered
gamma rays not adopted.
The next part compares, for each gamma ray, the adopted energy (Eg-ad)
with the energy calculated from levels (if known) minus the recoil energy
(DLv-Er) or with the energy that was entered for each data set. (Note that
the energies for some data sets include the recoil energy. This recoil
energy has been subtracted to get the energy of the gamma ray.) The recoil
energy (Er) is given for each gamma ray. Individual data entries can be
flagged (*) such that they are ignored in these comparisons. At the end of
the gamma-ray-energy comparison, the number of gamma rays compared and a
weighted (by the square root of the adopted intensity Ig) average absolute
deviation in energy ("WTD[SQRT(Ig)] AVG [ABS(DELTA-E)]") is given for "DLv-
Er" and for each data set. Each value for a given set of energies Eg
relative to the adopted energy Eg-ad is
WEIGHTED ABS(DELTA-E) = SUM[SQRT(Ig)*ABS(Eg-ad - Eg)]/Sum[SQRT(Ig)]
where SQRT is square root and ABS is the absolute value.
For intensities, the percent deviation of the input intensity (after any
normalization factor, Ig Norm, has been applied) from the adopted ("Ig-ad")
intensity are given for each gamma ray. Data entries can be flagged (*)
such that they are ignored in these comparisons. At the end of the
intensity comparison, the number of gamma rays compared and a weighted (by
square root of the intensity Ig) average for these percent deviations is
given for each data set:
WEIGHTED AVG[% DEVIATION]=SUM[SQRT(Ig)*ABS(1.0 - (Ig/Ig-ad))]*100/SUM[SQRT(Ig)]
where SQRT is square root and ABS is the absolute value.
A few comparisons are then made for the adopted intensities and for the
intensities for each data set. The sum of Eg*Ig and the sum of Eg*Ig
divided by Sn are given for each data set. The intensity sum out of the
capture level and the intensity sum into the ground state are also given.
Statistics for each of the major levels is then given. A level is
considered a major level when one of the sums of the intensity into or out
of the level is greater than 0.5%. The number and intensities of gamma rays
into and out of the major levels are given. These intensity sums are
rounded to the nearest %. (A good set should have about the same "in" and
"out" values for every level except the capture state and the ground state.)
TABLE 4 Experimental Prompt Gamma-Ray Data
This table has the published experimental data for gamma-ray energies
and intensities used to obtain the adopted gamma rays and to compare data
sets. After a title line, there is a line with the name(s) for the entered
data set(s). The NSR codes (e.g., 71Ar39) are used and are the same as in
the REFERENCES below. Occasionally the data were copied directly from the
National Nuclear Data Center (NNDC) website, and those data are often
denoted NNDC. Similarly, data copied from the evaluations done by
X Division at LANL are denoted as XCI. In a few cases, separate entries are made
for different tables in one reference, especially if each table needs to
have a different normalization factor.
The next line has the normalization factors applied to the intensities
for each data set. Often this normalization factor is just 1.0. In some
cases, the data were taken from a website with the strongest gamma ray given
an intensity of 100 (as for NNDC) or normalized in some fashion (as for
XCI), and the normalization factor converts those intensities to absolute
values. A minus sign before the normalization factor indicates that the
set's energies include the recoil energy so that the code can convert those
energies to gamma-ray energies.
There is one line of information for each gamma ray. After the energies
of the levels (rounded to the nearest keV) for the gamma-ray transition (if
known) are the energies (in keV) and intensities (nominally in %) for each
data set for a given gamma ray. A minus sign before an energy or intensity
indicates that that value is ignored in the comparisons.
TABLE 5 Energy Levels for Product Nucleus
The known energy levels for the product nucleus up to and including the
capture state are given in keV. After a title line and column headings,
there is a line that ends with a number that indicates the approximate value
for the largest uncertainty of the level energies in keV.
The energy level data are then given with one level per line. The
level's energy in keV is given, and if known, that level's spin (J) and
parity are given. A ? indicates that there is some uncertainty in the
adopted spin. If there are two possible adjacent spins, such as 1 and 2,
then the average of those two values (1.5) is given for the spin and the ?
indicates that the spin is not exact. In some cases, 3 adjacent spins are
possible (e.g., 1/2, 3/2, and 5/2) and the average (1.5) with a ? indicates
that there is an uncertainty in that adopted spin value. The letter C
indicates the capture state.
Often the data for these levels were taken from the 8th Edition of the
Table of Isotopes (Firestone et al., 1996). That source is often referred
to as ToI8 or a similar abbreviation.
REFERENCES
The full references of the literature sources used for that isotope are
given here. The references are in the NSR format as taken from the NSR
section of the website for the National Nuclear Data Center at the
Brookhaven National Laboratory. The NSR format (e.g., 71Ar39 or 1971Ar39)
has the year as the first 2 or 4 numbers, then the first 2 letters of the
first author's last name, and either a 2 digit number (starting with 01 for
journals) or 2 letters (starting with ZZ for other documents). References
here are first sorted by year than by the first author's name. In a very
few cases, an adopted reference is not in the NSR system and there is
nothing after the first two letters of the first author's last name (e.g.,
1993Pr).