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In order to determine the neutron capture cross sections in the astrophysical energy region (kTastro ~ 1 ... 100 keV),
the calorimetric 4π-BaF2 array DANCE at the Los Alamos National Laboratory has been built.
Driver of the experiments at LANSCE is a 800 MeV proton LINAC. High energy protons hit a tungsten spallation target
to produce a neutron flux spectrum. The beam lines are arranged radially around the target.
The DANCE detector at flightpath 14 consists of a spherical array of 160 4π-BaF2 scintillators equipped with PMT's.
Since almost the complete solid angle is covered, the sum energy of gamma cascades from single capture events can be measured.
This allows distinguishing between neutron captures on different isotopes based on the Q-value of the reaction.
The neutron energy is measured via the time-of-flight method. Additionally the event multiplicity (number of crystals fired)
can be used to discriminate background. |
