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).