We examined x-rays for the use as authentication and verification tool in treaty verification. Several x-ray pictures were taken to determine the quality and feasibility of x-rays for these tasks. This document describes the capability of the used x-ray system and outlines its parameters and possible use.

of students and postdocs. LANL's mission is to 'apply science and technology to: ensure the safety, security, and reliability of the US nuclear deterrent, reduce global threats, and solve other emerging national security challenges.' While LANL officially operates under the US Department of Energy (DoE), fulfilling this mission requires mutual cooperation with the US Department of Defense (DoD) as well. LANL's high concentration of knowledge and experience provides interns a chance to perform research in many disciplines, and its connection with the DoD in both operation and personnel gives SARA students insight to career possibilities both during and after military service. SARA students have plenty of opportunity to enjoy hiking, camping, the Los Alamos YMCA, and many other outdoor activities in New Mexico while staying at the Buffalo Thunder Resort, located 20 miles east of the lab. XCP Division is the Computational Physics division of LANL's Weapons Department. Working with XCP Division requires individuals to be Q cleared by the DoE. This means it is significantly more convenient for SARA students to be assigned to XCP Division than their civilian counterparts as the DoD CNWDI clearance held by SARA students is easily transferred to the lab prior to the students arriving at the start of the summer. SARA students working with XCP Division were given a comprehensive introduction into nuclear engineering and physics, nuclear weapons, and radiation transport and detection via texts and lectures at various classification levels. Students also attended tours of several prominent facilities at LANL including TA-41 Ice House, TA-55 PF-4 plutonium facility, the Nicholas C. Metropolis Center for Modeling and Simulation, also known as the Secure Computing Center (SCC), and the Dual-Axis Radiological Hydro Test (DARHT) facility; in addition, SARA students accompanied by LANL staff traveled to Minot AFB in North Dakota for tours of the 5th Bomb Wing and 91st Missile Wing facilities. Students participated in a week long class on the Monte Carlo N Particle (MCNP) code to supplement their understanding of radiation transport simulations. SARA students were then tasked with using this knowledge to model radiation detectors and use MCNP to compare their models to experimental data and previously accepted models.

1995, a four year study was initiated at LANL to assess the status of bat species of concern, elucidate distribution and relative abundance, and obtain information on roosting sites. There have been no definitive studies since then. Biologists in the Environmental Protection Division at LANL initiated a multi-year monitoring program for bats in May 2013 to implement the Biological Resources Management Plan. The objective of this ongoing study is to monitor bat species diversity and seasonal activity over time at LANL. Bat species diversity and seasonal activity were measured using an acoustic bat detector, the Pettersson D500X. This ultrasound recording unit is intended for long-term, unattended recording of bat and other high frequency animal calls. During 2013, the detector was deployed at two locations around LANL. Study sites were selected based on proximity to water where bats may be foraging. Recorded bat calls were analyzed using Sonobat, software that can help determine specific species of bat through their calls. A list of bat species at the two sites was developed and compared to lists from previous studies. Species diversity and seasonal activity, measured as the number of call sequences recorded each month, were compared between sites and among months. A total of 17,923 bat calls were recorded representing 15 species. Results indicate that there is a statistically significant relationship between bat diversity and month of the year. Future studies will be implemented based on these findings.

We have developed a dynamic gamma-ray emission image reconstruction method called MVIR (Moving Voxel Image Reconstruction) for lane detection in multilane portal monitor systems. MVIR was evaluated for use in the Fixed Site Detection System (FSDS), a prototype three-lane gamma-ray portal monitor system for EZ-pass toll plazas. As a baseline, we compared MVIR with a static emission image reconstruction method in analyzing the same real and simulated data sets. Performance was judged by the distributions of image intensities for source and no-source vehicles over many trials as a function of source strength. We found that MVIR produced significantly better results in all cases. The performance difference was greatest at low count rates, where source/no-source distributions were well separated with the MVIR method, allowing reliable source vehicle identification with a low probability of false positive identifications. Static emission image reconstruction of the same data produced overlapping distributions that made source vehicle identification unreliable. The performance of the static method was acceptable at high count rates. Both algorithms reliably identified two strong sources passing through at nearly the same time.

Transparent nanocomposites have been developed which consist of nanocrystals embedded in an organic matrix. The materials are comprised of up to 60% by volume of 7–13 nm crystals of the phosphor CexLa1−xF3, and are greater than 70% transparent in the visible region at a thickness of 1 cm. Consistencies of the nanocomposites range from a solid polymer to a wax to a liquid, depending on the workup conditions of the nanoparticle synthesis. These transparent nanophosphor composite materials have potential applications in radiation detection as scintillators, as well as in other areas such as imaging and lighting, and can be produced on large scales up to near-kilogram quantities at near ambient conditions, much lower in temperature than typical nanoparticle syntheses.

Neutron flux from linear accelerators is conventionally monitored using ionization chambers containing one or more foils thinly coated with a fissionable or fissile material. Due to the long pulse rise times resulting from the ionization mechanism, fission chambers are prone to pulse pile-up in high-neutron-flux environments. In addition, their relatively low efficiencies result in extremely long counting times in low-flux environments. To ameliorate these effects, a novel type of neutron flux monitor, consisting of fissionable material loaded in a liquid scintillator, has been developed, characterized, and tested in the beam line at the Los Alamos Neutron Science Center. This is a rugged, cost-efficient detector with high efficiency, a short signal rise time, and the ability to be used in low neutron-flux environments. Compared with a conventional fission chamber, the fissionable scintillator displays a significantly higher event rate. Related research on nanocomposite scintillators for gamma-ray detection suggests the possibility of extending this approach by synthesizing fissionable material nanoparticles and loading them into an organic scintillator. We will present results of the design and characterization process and an analysis of the results of the beam line experiments.

Muons, created by a particle accelerator, can be used to scan cargo for special nuclear materials (SNM). These muons have a sufficiently long lifetime and are penetrating enough that they can be used to actively scan cargo to ensure the non-proliferation of SNM. A set of "proof-of-concept" experiments have been performed to show that active muon analysis can be used. Experiments were performed at high intensity, medium energy particle accelerators (TRIUMF and PSI). Negative muons form exotic atoms with one electron replaced by the muon. Since the muon is captured in an excited state, it will give off x-rays which can be detected by high purity germanium detectors. The characteristic x-ray spectrum can be potentially used to identify nuclides. The muonic x-rays corresponding to the SNM of interest have been measured, even with the use of various shielding configurations composed of lead, iron, polyethylene, or fibreglass. These preliminary results show that muon scanning systems can be successfully used to find shielded SNM, helping to ensure the safety of all citizens.

Nanocomposite scintillators consist of nanoparticles of an inorganic scintillator dispersed in a matrix material. This technique is particularly well suited for applications requiring large or unusually shaped detectors, since these can be fabricated without requiring the growth of large crystals and using an inexpensive matrix. Nanocomposite scintillators may additionally make it possible to use scintillating materials not currently available in large sizes and quantities. Los Alamos National Laboratory is currently conducting a large nanocomposite scintillator development program. Several potential scintillator materials have been identified. We have successfully fabricated nanoparticles, for example CeF 3 , with sizes ≪ 10 nm and dispersed them in an optimized liquid scintillator solution and in several polymers. We have measured their size, structure, and radiation detection characteristics and have found good agreement between their scattering behavior and a Rayleigh scattering model. Current research results will be presented.

Enhancements contained in the current MCNPX 2.6.0 Radiation Safety Information Computational Center (RSICC) release will be presented, including stopped-muon physics, delayed neutron and photon generation, and automatic generation of source photons. Preliminary benchmarking comparisons with data taken with a muon beam at the Paul Scherrer Institute Spallation Neutron Source accelerator will be discussed. We will also describe current improvements now underway, including Nuclear Resonance Fluorescence (NRF), pulsed sources, and others. We will also describe very new work begun on a threat-reduction (TR) user interface, designed to simplify the setup of TR-related calculations, and introduce standards into geometry, sources and backgrounds.

The neutron capture cross section of $^{62}\mathrm{Ni}$ has been measured in the energy range relevant to the astrophysical $s$-process and Maxwellian-averaged cross sections (MACS) were extracted. The experiment was performed with an enriched $^{62}\mathrm{Ni}$ sample at a white neutron source using a 160 segment ${\mathrm{BaF}}_{2}$ detector array. The experimental results: $31.5\ifmmode\pm\else\textpm\fi{}2.{5}_{\mathrm{stat}}\ifmmode\pm\else\textpm\fi{}2.{2}_{\mathrm{sys}}$ mb (MACS at $\mathrm{kT}=25$ keV) and $25.8\ifmmode\pm\else\textpm\fi{}1.{8}_{\mathrm{stat}}\ifmmode\pm\else\textpm\fi{}1.{9}_{\mathrm{sys}}$ mb (MACS at $\mathrm{kT}=30$ keV) resolve a previous discrepancy between recent experiments.

The neutron capture cross section of 62 Ni has been measured in the energy range relevant to the astrophysical s-process and Maxwellian-averaged cross sections (MACS) were extracted. The experiment was performed with an enriched 62 Ni sample at a white neutron source using a 160 segment BaF 2 detector array. The experimental results: 31.5 ± 2.5 stat ± 2.2 sys mb (MACS at kT = 25 keV) and 25.8 ± 1.8 stat ± 1.9 sys mb (MACS at kT = 30 keV) resolve a previous discrepancy between recent experiments.

The Np-237(n, gamma) Np-238 cross section has been measured in the neutron energy range from 20 meV to 500 keV using the DANCE array at the Los Alamos National Laboratory. This new facility allows experiments with submilligram samples and is therefore well suited to investigate isotopes with half-lives as low as a few hundred days. In this benchmark measurement, only 0.42 mg of 237Np was sufficient to determine differential cross sections relative to the well-known resonance at 0.5 eV. The thermal cross section was measured to sigma(2200m/s) = 177 +/- 5 barn, sigma(kT= 25.3) meV = 167 +/- 4 barn and the resonance integral to RI = 693 +/- 6 barn.

We have made neutron capture cross-section measurements using the white neutron source at the Los Alamos Science Center, the DANCE detector array (Detector for Advanced Neutron Capture Experiments) and targets important for basic science and stockpile stewardship. In this paper, we review results from (n,{gamma}) reactions on {sup 94,95}Mo, {sup 152,154,157,160,nat}Gd, {sup 151,153}Eu and {sup 242m}Am for neutron energies from < 1eV up to {approx} 20 keV. We measured details of the {gamma}-ray cascade following neutron capture, for comparison with results of statistical model simulations. We determined the neutron energy dependent (n,{gamma}) cross section and gained information about statistical decay properties, including the nuclear level density and the photon strength function. Because of the high granularity of the detector array, it is possible to look at gamma cascades with a specified number of transitions (a specific multiplicity). We simulated {gamma}-ray cascades using a combination of the DICEBOX/GEANT computer codes. In the case of the deformed nuclei, we found evidence of a scissors-mode resonance. For the Eu, we also determined the (n,{gamma}) cross sections. For the {sup 94,95}Mo, we focused on the spin and parity assignments of the resonances and the determination of the photon strength functions for the compound nucleimore » {sup 95,96}Mo. Future plans include measurements on actinide targets; our immediate interest is in {sup 242m}Am.« less

The detector for advanced neutron capture experiments (DANCE) at Los Alamos National Laboratory (LANL) is used for neutron capture cross sections measurements. Its high granularity of 160 BaF2 detectors in a 4π geometry allows for highly efficient detection of prompt γ-rays following a neutron capture. The performance of the detector was simulated using the GEANT4 Monte Carlo code. The model includes all 160 BaF2 crystals with realistic dimensions and geometry. The 6LiH shell, beam pipe, crystal wrapping material, aluminum holders, photomultiplier material and materials of the calibration sources were included in the simulation. Simulated γ-ray energy and total γ-ray energy spectra gated on cluster and crystal multiplicities were compared to measured data using 88Y, 60Co, 22Na calibration sources. Good agreement was achieved. A total efficiency and peak-to-total ratio as a function of γ-ray energy was established for mono-energetic γ-rays.

An array of Neutral-Current Detectors (NCDs) has been built in order to make a unique measurement of the total active flux of solar neutrinos in the Sudbury Neutrino Observatory (SNO). Data in the third phase of the SNO experiment were collected between November 2004 and 2006, after the NCD array was added to improve the neutral-current sensitivity of the SNO detector. This array consisted of 36 strings of proportional counters filled with a mixture of 3He and CF4 gas capable of detecting the neutrons liberated by the neutrino-deuteron neutral-current reaction in the D2O, and four strings filled with a mixture of 4He and CF4 gas for background measurements. The proportional counter diameter is 5cm. The total deployed array length was 398m. The SNO NCD array is the lowest-radioactivity large array of proportional counters ever produced. This article describes the design, construction, deployment, and characterization of the NCD array, discusses the electronics and data acquisition system, and considers event signatures and backgrounds.