A new reference database for beta-delayed neutrons

A new database containing all available experimental and evaluated β-delayed neutron data is presented in this paper. The database is the product of an international effort coordinated by the International Atomic Energy Agency. It comprises a microscopic section including all available experimental data on beta-decay half-lives, β-delayed neutron emission probabilities and spectra, as well as new systematics and global theoretical calculations for comparison. The beta-delayed neutron data for individual precursors have been benchmarked against available data on macroscopic properties such as total delayed-neutron yields and spectra, delayed-neutron decay curves and time-dependent group parameters using the summation method. All available measured macroscopic data have also been compiled in the macroscopic section of the database. The dedicated database is available online on the IAEA server (URL:http://www-nds.iaea.org/beta-delayed-neutron/database.html).

The Los Alamos fission yield evaluation pipeline

The nuclear data team at Los Alamos National Laboratory has undertaken a campaign to construct new fission yield evaluation. Significant advances have been made on a number of fronts. Nuclear potential energy surfaces can now be generated with the newly developed MicMac code based off the Finite Range Liquid-Drop Model (FRLDM). This model can be incorporated into the Los Alamos de-excitation framework codes BeOH and CGMF to perform modeling of prompt, independent (IFY) and cumulative (CFY) fission yields that take into account prompt and beta-delayed neutrons and photons consistent with decay data. This is in stark contrast to what exists in evaluated nuclear data libraries today, where only a few incident energy points are used with limited physical insights and no consistency between IFY, CFY and decay data. We highlight the latest progress with application of neutron-induced fission of 235 U and 239 Pu.

Beta-delayed gamma spectra in CENDL-3.2

A new program is developed to compute the beta delayed fission gamma spectrum, and applied to compute the spectra of n+235U, 239Pu and 241Pu fissions wherein the recent nuclear database is adopted. The results show that most spectra are well in agreement with the data from ENDF/B-VII.0 library, and some are quite different, which should be caused by the improvement of the nuclear database.

Beta delayed neutron measurements by means of Modular Total Absorption Spectrometer

Possibility to use Modular Total Absorption Spectrometer (MTAS) as a device to measure complete decay scheme, including β-n of neutron rich isotopes, has been investigated. Analysis of well known 87Br with its 2.6% β-n branching ratio served as a test case. Preliminary results agree with the published data.