Engineering topics

Fry, Cathleen Elizabeth

Publications and source records attributed to Fry, Cathleen Elizabeth.

5 records

DOE OSTI2024

169 Tm(n,$\gamma$) cross section measured at DANCE

During the US nuclear testing program, known tracer materials could be loaded into the device prior to detonation. If those materials had activation products from nuclear reactions, they could be recovered and counted post-test to study how they transmuted during the neutron exposure. This information may be used to try to infer information about the physical conditions during the detonation. These materials are often referred to as “radiochemical detectors” or “radiochemical tracers”. Thulium, which has only one stable isotope, thulium-169, is one such material that may be employed as a detector.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

DOE OSTI2024

GEANT4 code for DANCE with NEUANCE detector-response simulations

A new GEANT4 model for DANCE with NEUANCE has been developed to account for the change in the DANCE configuration when NEUANCE is installed. In this model, the energy resolution and the shape of the threshold of the individual DANCE detectors are used as an input to provide realistic representation of the measured γ-ray spectra. In addition, the distance from each detector to the target is defined in an input file as well as the physical presence of the a detector in the DANCE and NEUANCE arrays. The azimuthal angle of NEUANCE is also an external parameter to be tuned to represent the measurement. Simulated spectra are compared with measurements with standard γ-ray calibrated sources.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

DOE OSTI2024

Neutron-induced capture-to-fission cross section ratio measured at LANSCE

Capture-to-fission cross section ratios are used as an alternative to absolute cross section measurements. This is due to the simplification on the calculations and the reduction of the uncertainties with respect to an absolute measurement of the cross section by eliminating experimental complications like self-absorption, beam/target overlap and non-uniformities. Different capture-to-fission reactions have been measured through the years at the Los Alamos Neutron Science Center (LANSCE) at Los Alamos National Laboratory (LANL) using the Detector for Advanced Neutron Capture Experiments (DANCE) combined with different fission detectors. Some of these are a Parallel Plate Avalanche Counter (PPAC) to detect fission fragments (FF), and the NEUtron detector array at DANCE (NEUANCE) to detect fission neutrons. As DANCE detects the γ-rays produced in capture and fission reactions, the fission instrument placed inside the DANCE cavity is used to tag the fission γ-rays for background identification and subtraction. Some examples of capture-to-fission ratio measurements performed with DANCE in the last years are the 233 U, 235 U and 239 Pu. The measurement technique, the different setups, and other potential applications of the instruments will be explained.

Nuclear Criticality Safety Program (NCSP)↗

DOE OSTI2024

Optimization of the gamma reaction history diagnostic for double-shell pusher areal density and reaction history measurements on the National Ignition Facility

The double-shell inertial confinement fusion campaign, which consists of an aluminum ablator, a foam cushion, a high-Z pusher (tungsten or molybdenum), and liquid deuterium–tritium (DT) fuel, aims for its first DT filled implosions on the National Ignition Facility (NIF) in 2024. The high-Z, high density pusher does not allow x-rays to escape the double-shell capsule. Therefore, nuclear diagnostics such as the Gamma Reaction History (GRH) diagnostic on the NIF are crucial for understanding high-Z implosion performance. To optimize the GRH measurement of fusion reaction history and the pusher’s areal density, the MCNP6.3-based forward model of the detector was built. When calculating the neutron-induced inelastic gamma ray production, the interaction of neutrons with the compressed fuel was additionally included. By folding the calculated gamma ray spectrum output and the previously calibrated GRH detector responses, the optimum set of GRH energy thresholds for measuring the pusher areal density is determined to be 2.9 and 6.3 MeV for DT double-shell experiments. In addition, the effect of the down-scattering of neutrons on the gamma ray spectrum, the minimum required yield for measurements, and the attenuation of the gamma rays through the pusher are analyzed.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

DOE OSTI2022

Experimental study of the 34 m Cl beam production at intermediate energies

Here the isomeric content of a 34 Cl beam produced in the intermediate-energy projectile fragmentation of a 150 MeV/u 36 Ar beam on a 3 mm-thick Be target was studied. β-delayed γ-ray spectroscopy was used to measure the population of 34 Cl fragments in the ground vs. isomeric states at zero degrees relative to the incoming primary beam for four different momentum settings of the fragment separator near the predicted central velocity of these fragments, as well as, at two non-zero-degree settings for one momentum setting. Of the settings explored, which excluded rigidities within 0.5% of the value predicted to maximize total 34 Cl yield due to unreacted primary beam, the maximum rate for the production of Cl was found at a rigidity setting 0.75% below the predicted peak 34 Cl yield. The maximum population of the isomeric state relative to the ground state was observed at a rigidity 1.25% below the predicted maximum 34 Cl yield. Studies such as this are important in generating the understanding needed for producing isomer-enriched rare-isotope beams.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗