The Versatile Array of Neutron Detectors at Low Energy
- Stanley Paulauskas, University of Tennessee
Wednesday, July 17, 4:00 PM - Special Seminar
NSCL Lecture Hall
As nuclei become more neutron rich, the nuclear structure changes their properties. For example, beta decays will access increasingly more neutron unbound states. The measurement of neutrons emitted from these states is critical, as beta-delayed neutron emission becomes a dominating decay mode.
To this end, the Versatile Array of Neutron Detectors at Low Energy (VANDLE) measures the energy of neutrons emitted from nuclear excited states populated through beta decay or transfer reactions. The time-of-flight technique determines the energy, which requires a time resolution on the order of 1 ns. In addition, the detector requires a low detection threshold to measure neutron energies of 100 keV or lower.
VANDLE accomplishes these design goals by combining plastic scintillators with a digital data acquisition system. This system uses XIAs DGF Pixie-16 hardware. We designed an algorithm for the extraction of sub-sample time information from digitized waveforms and a new triggering scheme.
A successful experimental campaign at the Holifield Radioactive Ion Beam Facility, using ions produced via proton induced fission on 238U, has yielded preliminary results on beta-delayed neutrons in the 78Ni region. Of particular interest, several nuclei unexpectedly displayed high energy neutrons. Results from this experiment and plans for future experiments will be presented.