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At least 1,621 records · Page 90
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

The new Device for Indirect Capture Experiments on Radionuclides at LANSCE: Efforts on measuring the resonance(s) responsible for the extremely large 88 Zr (n,γ) cross section

The thermal neutron capture cross section of 88 Zr was recently reported to be the second largest in nature with the largest resonance integral measured. Presumably, these very large values are caused by a resonance or resonances very near thermal energy. Determining their energies and widths, and hence the shape of the cross section away from thermal energies,is useful for applications. The short half-life (83.4 days) and associated large background, renders direct measurements of the neutron capture cross section impossible using current techniques. However, it is possible to measure the total neutron cross section, and hence the resonance properties, using the newly commissioned Device for Indirect Capture Experiments on Radionuclides (DICER) at the Los Alamos Neutron Science Center (LANSCE). Transmission measurements are utilized as a surrogate method to perform capture measurements. The 88 Zr needed for a DICER measurement was produced at the Isotope Production Facility (IPF) and cleanly separated from the production target material. A description of the new instrument, efforts and preliminary results on 88 Zr will be presented.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2023

Data Assimilation using Non-invasive Monte Carlo Sensitivity Analysis of Reactor Kinetics Parameters

Accurately predicting the criticality of an experiment before interacting with the experimental components is very important for criticality safety. Radiation transport software can be utilized to calculate the effective neutron multiplication factor of a nuclear system. Because of the integral nature of the effective neutron multiplication factor, the value calculated contains various sources of nuclear-data induced uncertainty. The sensitivity analysis and data assimilation technique presented in this paper exhibit one possible method of identifying and reducing the effective neutron multiplication factor nuclear-data induced uncertainty. The results presented in this work show that it is possible to use relative sensitivity coefficients of the prompt neutron decay constant and the effective delayed neutron fraction to 239 Pu nuclear data to reduce nuclear-data induced uncertainties in the effective neutron multiplication factor. This work has been utilized by members of the Los Alamos National Laboratory project EUCLID (Experiments Underpinned by Computational Learning for Improvements in Nuclear Data) for optimally designing a new experiment, which will be used to reduce compensating errors in 239 Pu nuclear data.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2019

Investigating the Potential for Recovering REEs from Coal Fly Ash and Power Plant Wastewater with an Engineered Sorbent

The global demand for rare earth elements (REE) has increased significantly in the past 20 years due to their extensive use in electronics and other applications. Although many recent studies related to quantifying rare earth elements in coal and coal combustion byproducts have been published, methods of extracting rare earth elements are still not economically feasible. The objective of our study is to investigate the potential extraction of the REEs from coal ash and from wastewater sludge collected from a power plant near Detroit, MI. The collected ash and sludge will undergo a hydrothermal extraction process developed by Los Alamos National Laboratory to extract REEs from the sludge or coal ash, resulting in a liquid enriched in dissolved REEs. Batch experiments were conducted using an organosilica adsorbent (Osorb) and a ligand [P-di(2-ethylhexyl) methanediphosphonic acid (DIPEX)] to extract neodymium from a synthetic hydrothermal extraction solution. DIPEX-associated Osorb media was produced by first dissolving DIPEX into a solvent (e.g., methanol). Different amounts of DIPEX-methanol solution were then added to 0.2 g of Osorb to determine the maximum sorption capacity. The methanol was evaporated and, after a rinse step, the DIPEX-Osorb sorbent was used in sorption experiments. A 300 ppm neodymium (Nd) synthetic ash/sludge leachate was tested with the various DIPEX-Osorb media. Results show that DIPEX-Osorb ratios of 4.3, 1.1, 0.5, and 0.05 mL/g sorbed 60, 51, 25, and 7 mg Nd per g media, respectively. Since the 4.3 mL DIPEX/g Osorb media sorbed 100% of the Nd in the solution, a higher capacity is expected and these experiments are ongoing. Breakthrough curve for of the sorption of Nd to Osorb was conducted and showed a higher sorption ratio when the Nd concentration increased. We are also investigating the reusability of the DIPEX-Osorb media by measuring how many cycles the media can be regenerated by extracting the Nd with nitric acid and reusing the sorbent for another cycle.

01 COAL, LIGNITE, AND PEAT↗
DOE OSTI2011

Effect of Ion Escape Velocity and Conversion Surface Material on H- Production

According to generally accepted models surface production of negative ions depends on ion escape velocity and work function of the surface. We have conducted an experimental study addressing the role of the ion escape velocity on H- production. A converter-type ion source at Los Alamos Neutron Science Center was employed for the experiment. The ion escape velocity was affected by varying the bias voltage of the converter electrode. It was observed that due to enhanced stripping of H- no direct gain of extracted beam current can be achieved by increasing the converter voltage. The conversion efficiency of H- was observed to vary with converter voltage and follow the existing theories in qualitative manner. We present calculations predicting relative H- yields from different cesiated surfaces with comparison to experimental observations from different types of H- ion sources. Utilizing materials exhibiting negative electron affinity and exposed to UV-light is considered for Cesium-free H-/D- production.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2012

Refurbishment and Testing of the 1970's Era LASS Solenoid Coils for JLab's Hall D

JLab refurbished the LASS1, 1.85 m bore Solenoid, consisting of four superconducting coils to act as the principal analysis magnet for nuclear physics in the newly constructed, Hall D at Jefferson Lab. The coils, built in 1971 at Stanford Linier Accelerator Center and used a second time at the MEGA Experiment at Los Alamos, had electrical shorts and leaks to the insulating vacuum along with deteriorated superinsulation & instrumentation. Root cause diagnosis of the problems and the repair methods are described along with the measures used to qualify the vessels and piping within the Laboratory's Pressure Safety Program (mandated by 10CFR851). The extraordinary refrigerator operational methods used to utilize the obsolete cryogenic apparatus gathered for the off-line, single coil tests are described.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2012

A furnace with rotating load frame for in situ high temperature deformation and creep experiments in a neutron diffraction beam line

A resistive furnace combined with a load frame was built that allows for in situ neutron diffraction studies of high temperature deformation, in particular, creep. A maximum force of 2700 N can be applied at temperatures up to 1000 deg. C. A load control mode permits studies of, e.g., creep or phase transformations under applied uni-axial stress. In position control, a range of high temperature deformation experiments can be achieved. The examined specimen can be rotated up to 80 deg. around the vertical compression axis allowing texture measurements in the neutron time-of-flight diffractometer HIPPO (High Pressure - Preferred Orientation). We present results from the successful commissioning, deforming a Zr-2.5 wt.% Nb cylinder at 975 deg. C. The device is now available for the user program of the HIPPO diffractometer at the LANSCE (Los Alamos Neutron Science Center) user facility.

36 MATERIALS SCIENCE↗
DOE OSTI2012

A multi-frame soft x-ray pinhole imaging diagnostic for single-shot applications

For high energy density magnetized target fusion experiments at the Air Force Research Laboratory FRCHX machine, obtaining multi-frame soft x-ray images of the field reversed configuration (FRC) plasma as it is being compressed will provide useful dynamics and symmetry information. However, vacuum hardware will be destroyed during the implosion. We have designed a simple in-vacuum pinhole nosecone attachment, fitting onto a Conflat window, coated with 3.2 mg/cm{sup 2} of P-47 phosphor, and covered with a thin 50-nm aluminum reflective overcoat, lens-coupled to a multi-frame Hadland Ultra intensified digital camera. We compare visible and soft x-ray axial images of translating ({approx}200 eV) plasmas in the FRX-L and FRCHX machines in Los Alamos and Albuquerque.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2012

Generation of magnetized collisionless shocks by a novel, laser-driven magnetic piston

We present experiments on the Trident laser facility at Los Alamos National Laboratory which demonstrate key elements in the production of laser-driven, magnetized, laboratory-scaled astrophysical collisionless shocks. These include the creation of a novel magnetic piston to couple laser energy to a background plasma and the generation of a collisionless shock precursor. We also observe evidence of decoupling between a laser-driven fast ion population and a background plasma, in contrast to the coupling of laser-ablated slow ions with background ions through the magnetic piston. 2D hybrid simulations further support these developments and show the coupling of the slow to ambient ions, the formation of a magnetic and density compression pulses consistent with a collisionless shock, and the decoupling of the fast ions.

36 MATERIALS SCIENCE↗
DOE OSTI2012

Obtaining material identification with cosmic ray radiography

The passage of muons through matter is dominated by the Coulomb interaction with electrons and nuclei in the matter. The muon interaction with the electrons leads to continuous energy loss and stopping of the muons. The muon interaction with nuclei leads to angular diffusion. Using both stopped muons and angle diffusion interactions allows us to determine density and identify materials. Here we demonstrate material identification using data taken at Los Alamos with a particle tracker built from a set of sealed drift tubes with commercial electronics and software, the Mini Muon Tracker (MMT).

36 MATERIALS SCIENCE↗
DOE OSTI2012

Possibility for ultra-bright electron beam acceleration in dielectric wakefield accelerators

We describe a conceptual proposal to combine the Dielectric Wakefield Accelerator (DWA) with the Emittance Exchanger (EEX) to demonstrate a high-brightness DWA with a gradient of above 100 MV/m and less than 0.1% induced energy spread in the accelerated beam. We currently evaluate the DWA concept as a performance upgrade for the future LANL signature facility MaRIE with the goal of significantly reducing the electron beam energy spread. The preconceptual design for MaRIE is underway at LANL, with the design of the electron linear accelerator being one of the main research goals. Although generally the baseline design needs to be conservative and rely on existing technology, any future upgrade would immediately call for looking into the advanced accelerator concepts capable of boosting the electron beam energy up by a few GeV in a very short distance without degrading the beam's quality. Scoping studies have identified large induced energy spreads as the major cause of beam quality degradation in high-gradient advanced accelerators for free-electron lasers. We describe simulations demonstrating that trapezoidal bunch shapes can be used in a DWA to greatly reduce the induced beam energy spread, and, in doing so, also preserve the beam brightness at levels never previously achieved. This concept has the potential to advance DWA technology to a level that would make it suitable for the upgrades of the proposed Los Alamos MaRIE signature facility.

43 PARTICLE ACCELERATORS↗
DOE OSTI2013

Reactivity worth measurements at the IPEN/MB-01 nuclear reactor

Researches that aim to improve the performance of neutron transport codes and quality of nuclear cross section databases are very important to increase the accuracy of simulations and the quality of the analysis and prediction of phenomena in the nuclear field. In this context, relevant experimental data such as reactivity worth measurements are needed. The objective of this work was to perform a series of experiments of reactivity worth measurements, using a digital reactivity meter developed at IPEN. The experiments employed small metallic and ceramic samples inserted in the central region of the core of the experimental IPEN/MB-01 reactor. The theoretical analysis was performed by the MCNP-5 reactor physics code, developed and maintained by Los Alamos National Laboratory, and the ENDF/B-VII.0 nuclear data library.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2013

Integrated experimental setup for angle resolved photoemission spectroscopy of transuranic materials

We have developed the Angle Resolved Photoemission Spectroscopy (ARPES) system for transuranic materials. The ARPES transuranic system is an endstation upgrade to the Laser Plasma Light Source (LPLS) at Los Alamos National Laboratory. The LPLS is a tunable light source for photoemission with a photon energy range covering the vacuum ultraviolet (VUV) and soft x-ray regions (27–140 eV). The LPLS was designed and developed for transuranic materials. Transuranic photoemission is currently not permitted at the public synchrotrons worldwide in the VUV energy range due to sample encapsulation requirements. With the addition of the ARPES capability to the LPLS system there is an excellent opportunity to explore new details centered on the electronic structure of actinide and transuranic materials.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2012

Current status of MCNP6 as a simulation tool useful for space and accelerator applications

For the past several years, a major effort has been undertaken at Los Alamos National Laboratory (LANL) to develop the transport code MCNP6, the latest LANL Monte-Carlo transport code representing a merger and improvement of MCNP5 and MCNPX. We emphasize a description of the latest developments of MCNP6 at higher energies to improve its reliability in calculating rare-isotope production, high-energy cumulative particle production, and a gamut of reactions important for space-radiation shielding, cosmic-ray propagation, and accelerator applications. We present several examples of validation and verification of MCNP6 compared to a wide variety of intermediate- and high-energy experimental data on reactions induced by photons, mesons, nucleons, and nuclei at energies from tens of MeV to about 1 TeV/nucleon, and compare to results from other modern simulation tools.

ACCELERATORS↗
DOE OSTI2014

Process model and capacity upgrades of the CTI-4000 liquid helium coldbox

Fermi National Accelerator Laboratory (FNAL) is in the process of re-commissioning a vintage CTI-4000 liquid helium coldbox, initially supplied by CTI-Cryogenics/Sulzer to Los Alamos in 1979. The coldbox was originally designed as a liquid helium refrigerator with capacity of ∼1200 W at nominal 4-K. The process utilized LN{sub 2} precooling, in-series operation of two centrifugal gas bearing turboexpanders and final Joule-Thomson (J-T) expansion. At FNAL, the coldbox will be utilized as a liquefier to support 2-K operations. A process model was developed to aid in the upgrade decisions and used to determine the nominal capacity of the liquefier. Capacity upgrades are achieved by safely utilizing the internal LN2 precooler, the addition of a 3-inch reciprocating wet expansion engine and increasing the overall process pressure by recertifying two limiting pressure vessels to a higher MAWP.

43 PARTICLE ACCELERATORS↗
DOE OSTI2014

Analysis of muon radiography of the Toshiba nuclear critical assembly reactor

A 1.2 × 1.2 m{sup 2} muon tracker was moved from Los Alamos to the Toshiba facility at Kawasaki, Japan, where it was used to take ∼4 weeks of data radiographing the Toshiba Critical Assembly Reactor with cosmic ray muons. In this paper, we describe the analysis procedure, show results of this experiment, and compare the results to Monte Carlo predictions. The results validate the concept of using cosmic rays to image the damaged cores of the Fukushima Daiichi reactors.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2014

Adventures in scientific nuclear diplomacy

A former director of Los Alamos National Laboratory offers a first-person perspective on the important contributions scientists can make toward improving the safety and security of nuclear materials and reducing the global nuclear dangers in an evolving world.

98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL P↗
DOE OSTI2014

Raising gradient limitations in 2.1 GHz superconducting photonic band gap accelerator cavities

We report results from recent 2.1 GHz superconducting radio frequency (SRF) photonic band gap (PBG) resonator experiments at Los Alamos. Two 2.1 GHz PBG cells with elliptical rods were fabricated and tested at high power in a liquid helium bath at the temperatures of 4 K and below 2 K. The described SRF PBG cells were designed with a particular emphasis on changing the shape of the PBG rods to reduce peak surface magnetic fields and at the same time to preserve its effectiveness at damping higher-order-modes. The superconducting PBG cavities have great potential for damping long-range wakefields in SRF accelerator structures without affecting the fundamental accelerating mode. The cells performed in accordance with simulation's predictions and the maximum achieved accelerating gradient was 18.3 MV/m. This represents a 30% increase over gradients previously demonstrated in superconducting PBG cavities with round rods.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗