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When multiple neutrons are emitted in a fission event they are correlated in both energy and their relative angle, which may impact the design of safeguards equipment and other instrumentation for non-proliferation applications. The most recent release of MCNP 6 . 2 contains the capability to simulate correlated fission neutrons using the event generators CGMF and FREYA . These radiation transport simulations will be post-processed by the detector response code, DRiFT , and compared directly to correlated fission measurements. DRiFT has been previously compared to single detector measurements, its capabilities have been recently expanded with correlated fission simulations in mind. This paper details updates to DRiFT specific to correlated fission measurements, including tracking source particle energy of all detector events (and non-events), expanded output formats, and digitizer waveform generation.

The SPectrometer for Ion DEtermination in fission Research (SPIDER) has been developed for measuring mass yield distributions of fission products from spontaneous and neutron-induced fission. The 2 E –2 v method of measuring the kinetic energy ( E ) and velocity ( v ) of both outgoing fission products has been utilized, with the goal of measuring the mass of the fission products with an average resolution of 1 atomic mass unit (amu). The SPIDER instrument, consisting of detector components for time-of-flight, trajectory, and energy measurements, has been assembled and tested using 229 Th and 252 Cf radioactive decay sources. For commissioning, the fully assembled system measured fission products from spontaneous fission of 252 Cf. Individual measurement resolutions were met for time-of-flight (250 ps FWHM), spacial resolution (2 mm FHWM), and energy (92 keV FWHM for 8.376 MeV). Mass yield results measured from 252 Cf spontaneous fission products are reported from an E – v measurement.

A digital data acquisition system has been combined with a double Frisch gridded ionization chamber for use at both moderated and unmoderated neutron sources at the Los Alamos Neutron Science (LANSCE) facility. The high efficiency of the instrument combined with intense LANSCE beams and new acquisition system permits fission output measurements across 11 orders of magnitude incident neutron energy. The acquisition and analysis system is presented along with the first in-beam performance tests of the setup.

A scintillator based hodoscope array was recently constructed at the National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University. The hodoscope will be used to measure the total kinetic energy of fragments in the focal plane of the large S800 magnetic spectrometer at the NSCL to provide atomic charge-state identification. The array consists of 32 closely packed 7.6 cm ×7.6 cm ×5.1 cm CsI(Na) crystals each coupled to a photomultiplier. All of the crystals were characterized with a γ -ray source prior to installation in the focal plane of the spectrometer. The hodoscope was then tested with a mono-energetic 76Ge primary beam as well as heavy ions from fragmentation reactions. The array is currently in place and has already been used in several recent experiments. The results of characterization of the properties of the crystals are presented here.

Two new experiments were carried out at the NSCL to explore the details of the linear moment and excitation energy distributions of projectile fragmentation production. In the first experiment the full linear momentum distributions of fragments from the reaction of a 76 Ge beam with beryllium and gold targets were measured in the S800 spectrometer. The results indicate a strong contribution of "far side" or attractive scattering to the near-projectile products with the gold target. In the second experiment the excitation energy of primary projectile fragments from peripheral nuclear reactions at intermediate energies was carried out at the NSCL. Sodium, neon and fluorine isotopes produced by the fragmentation of a neutron-rich 32Mg beam by a beryllium target were observed in a magnetic spectrometer in coincidence with fast neutrons detected using the Modular Neutron Array (MoNA). A new technique based on an analysis of the observed neutron multiplicity distributions was used to estimate the excitation energy and mass of the precursor intermediate products for the first time. A strong correlation between the neutron multiplicity and the total mass loss was observed indicating that large excitation energies were created in the prefragments by the initial collision. These findings are generally consistent with the internuclear cascade model of the collision dynamics but not with macroscopic abrasion-ablation models.