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The normalization γ ray in the (n,n'γ) ATLAS is the 847-keV 2+1 → 0+gs transition in 56Fe which has a relative intensity (RI) of 100 units. We are adopting a measured partial γ-ray production cross section (σγ) of 468 mb for this transition. To extract cross sections relative to this measurement we add the following code to our SQL transactions:
CREATE TEMP TABLE _Variables(
Name TEXT PRIMARY KEY,
FeCS FLOAT,
FeRatio FLOAT,
RI FLOAT
);
INSERT OR REPLACE INTO _Variables VALUES ('Constant', 468.0, 4.68, 100.0);
Here, FeCS=468.0 is σγ for the 56Fe transition, RI=100.0 is the relative intensity of the 56Fe transition, and FeRatio=4.68 is the ratio σγ(56Fe)/RI(56Fe). These variables can be adjusted to accommodate user-specified values. Several SQL scripts utilizing the above "global variables" temporary table are provided in the examples directory ~/BaghdadAtlas/sql_codes, e.g., getDyCs_Vars.sql which calculates partial cross sections and associated uncertainties for transitions in natural dysprosium. A similar script that does not use the temporary-table method above is also provided for comparison, getFeCS.sql which calculates partial cross sections and associated uncertainties for transitions in natural iron. Note that the extension library (Linux: libsqlitefunctions.so, Mac OS X: libsqlitefunctions.dylib) must be loaded into these transactions because nonstandard-sqlite3 functionality is being used. The appropriate library gets defined automatically during installation. The SQL scripts affected should also contain the following OS-dependent transactions:
SELECT load_extension('../UDF/sqlite-amalgamation/libsqlitefunctions.so'); /* Linux library */
SELECT load_extension('../UDF/sqlite-amalgamation/libsqlitefunctions.dylib'); /* Mac OS X library */
Alternatively, cross-section calculations may also be performed using the Jupyter Notebook. To illustrate this, a CrossSection class has been defined in one of the cells in the example notebook sql_queries_atlas.ipynb provided in ~/BaghdadAtlas/notebook_analysis. The class constants FeCS, FeRatio, and RI are defined as above. The cross sections for natRe(n,n'γ), for example, are shown here. To calculate cross sections for a different nucleus change the atomic number (Z), chemical symbol (Chem_symb), and atomic mass (A) to that of the nucleus of interest in the corresponding cell.