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Reversible Electron Beam Heating for Suppression of Micro bunching Instabilities at Free-Electron Lasers

Description: The presence of microbunching instabilities due to the compression of high-brightness electron beams at existing and future x-ray free-electron lasers (FELs) results in restrictions on the attainable lasing performance and renders beam imaging with optical transition radiation impossible. The instability can be suppressed by introducing additional energy spread, i.e., heating the electron beam, as demonstrated by the successful operation of the laser heater system at the Linac Coherent Light So… more
Date: May 30, 2012
Creator: Behrens, Christopher; Huang, Zhirong & Xiang, Dao
Partner: UNT Libraries Government Documents Department
open access

Requirements for Computer Based-Procedures for Nuclear Power Plant Field Operators Results from a Qualitative Study

Description: Although computer-based procedures (CBPs) have been investigated as a way to enhance operator performance on procedural tasks in the nuclear industry for almost thirty years, they are not currently widely deployed at United States utilities. One of the barriers to the wide scale deployment of CBPs is the lack of operational experience with CBPs that could serve as a sound basis for justifying the use of CBPs for nuclear utilities. Utilities are hesitant to adopt CBPs because of concern over pot… more
Date: May 1, 2012
Creator: Blanc, Katya Le & Oxstrand, Johanna
Partner: UNT Libraries Government Documents Department
open access

Design and Simulation of IOTA - a Novel Concept of Integrable Optics Test Accelerator

Description: The use of nonlinear lattices with large betatron tune spreads can increase instability and space charge thresholds due to improved Landau damping. Unfortunately, the majority of nonlinear accelerator lattices turn out to be nonintegrable, producing chaotic motion and a complex network of stable and unstable resonances. Recent advances in finding the integrable nonlinear accelerator lattices have led to a proposal to construct at Fermilab a test accelerator with strong nonlinear focusing which … more
Date: May 1, 2012
Creator: Nagaitsev, S.; Valishev, A.; /Fermilab; Danilov, V.V.; Ridge, /Oak; Shatilov, D.N. et al.
Partner: UNT Libraries Government Documents Department
open access

Shielding of a hadron in a finite e-beam

Description: The thorough study of coherent electron cooling, the modern cooling technique capable to deal with accelerators operating in the range of few TeVs, rises many interesting questions. One of them is a shielding dynamics of a hadron in an electron beam. Now this effect is computed analytically in the infinite beam approximation. Many effects are drastically different in finite and infinite plasmas. Here we propose a method to compute the dynamical shielding effect in a finite cylindrical plasma - … more
Date: May 20, 2012
Creator: A., Elizarov; Litvinenko, V. & Wang, G.
Partner: UNT Libraries Government Documents Department
open access

Simulation and Experiment of Thermal Fatigue in the CPV Die Attach: Preprint

Description: FEM simulation and accelerated thermal cycling have been performed for the CPV die attach. Trends in fatigue damage accumulation and equivalent test time are explored and found to be most sensitive to temperature ramp rate. Die attach crack growth is measured through cycling and found to be in excellent agreement with simulations of the inelastic strain energy accumulated. Simulations of an entire year of weather data provides for the relative ranking of fatigue damage between four cites as wel… more
Date: May 1, 2012
Creator: Bosco, N.; Silverman, T. & Kurtz, S.
Partner: UNT Libraries Government Documents Department
open access

Compact proton spectrometers for measurements of shock

Description: The compact Wedge Range Filter (WRF) proton spectrometer was developed for OMEGA and transferred to the National Ignition Facility (NIF) as a National Ignition Campaign (NIC) diagnostic. The WRF measures the spectrum of protons from D-{sup 3}He reactions in tuning-campaign implosions containing D and {sup 3}He gas; in this work we report on the first proton spectroscopy measurement on the NIF using WRFs. The energy downshift of the 14.7-MeV proton is directly related to the total {rho}R through… more
Date: May 2, 2012
Creator: Mackinnon, A.; Zylstra, A.; Frenje, J. A.; Seguin, F. H.; Rosenberg, M. J.; Rinderknecht, H. G. et al.
Partner: UNT Libraries Government Documents Department
open access

A novel particle Time Of Flight (pTOF) diagnostic for measurements of shock- and compression-bang times in D3He and DT implosions at the NIF

Description: The particle-time-of-flight (pTOF) diagnostic, fielded alongside a Wedge Range-Filter (WRF) proton spectrometer, will provide an absolute timing for the shock-burn weighted {rho}R measurements that will validate the modeling of implosion dynamics at the National Ignition Facility (NIF). In the first phase of the project, pTOF has recorded accurate bang times in cryogenic DT, DT-Exploding Pusher and D{sup 3}He implosions using DD or DT neutrons with an accuracy better than {+-}70 ps. In the seco… more
Date: May 2, 2012
Creator: Mackinnon, A.; Rinderknecht, H. G.; Johnson, M. G.; Zylstra, A. B.; Sinenian, N.; Rosenbergh, M. J. et al.
Partner: UNT Libraries Government Documents Department
open access

Kepler constraints on planets near hot Jupiters

Description: We present the results of a search for planetary companions orbiting near hot Jupiter planet candidates (Jupiter-size candidates with orbital periods near 3 d) identified in the Kepler data through its sixth quarter of science operations. Special emphasis is given to companions between the 2:1 interior and exterior mean-motion resonances. A photometric transit search excludes companions with sizes ranging from roughly two-thirds to five times the size of the Earth, depending upon the noise prop… more
Date: May 1, 2012
Creator: Steffen, Jason H.; Ragozzine, Darin; Fabrycky, Daniel C.; Carter, Joshua A.; Ford, Eric B.; Holman, Matthew J. et al.
Partner: UNT Libraries Government Documents Department
open access

Recent T980 Crystal Collimation Studies at the Tevatron Exploiting a Pixel Detector System and a Multi-Strip Crystal Array

Description: With the shutdown of the Tevatron, the T-980 crystal collimation experiment at Fermilab has been successfully completed. Results of dedicated beam studies in May 2011 are described in this paper. For these studies, two multi-strip crystals were installed in the vertical goniometer and an O-shaped crystal installed in a horizontal goniometer. A two-plane CMS pixel detector was also installed in order to enhance the experiment with the capability to image the profile of crystal channeled or multi… more
Date: May 15, 2012
Creator: Still, D.; Annala, G. E.; Carrigan, R. A.; Drozhdin, A. I.; Johnson, T. R.; Mokhov, N. V. et al.
Partner: UNT Libraries Government Documents Department
open access

Saturation and Dynamic Range of Microchannel Plate-Based X-Ray Imagers

Description: This paper describes recent advances in Monte Carlo simulations of microchannel plate (MCP)–based x-ray detectors, a continuation of ongoing work in this area. A Monte Carlo simulation model has been developed over the past several years by National Security Technologies, LLC (NSTec). The model simulates the secondary electron emission process in an MCP pore and includes the effects of gain saturation. In this work we focus on MCP gain saturation and dynamic range. We have performed modeling an… more
Date: May 4, 2012
Partner: UNT Libraries Government Documents Department
open access

Design of Accumulator and Compressor Rings for the Project-X Based Proton Driver

Description: A Muon Collider (MC) and a Neutrino Factory (NF) - which may be considered as a step towards a MC - both require a high-power ({approx}4 MW) proton driver providing short (<1 m r.m.s. length) bunches for muon production. However, the driver repetition rates required for these two machines are different: {approx}15 Hz for MC and {approx}60 Hz for NF. This difference suggests employing two separate rings: one for accumulation of the proton beam from the Project-X linac in a few (e.g. 4) long b… more
Date: May 1, 2012
Creator: Alexahin, Y. & Neuffer, D.
Partner: UNT Libraries Government Documents Department
open access

Gas-Phase Molecular Dynamics: Theoretical Studies In Spectroscopy and Chemical Dynamics

Description: The main goal of this program is the development and application of computational methods for studying chemical reaction dynamics and molecular spectroscopy in the gas phase. We are interested in developing rigorous quantum dynamics algorithms for small polyatomic systems and in implementing approximate approaches for complex ones. Particular focus is on the dynamics and kinetics of chemical reactions and on the rovibrational spectra of species involved in combustion processes. This research al… more
Date: May 29, 2012
Creator: Yu, H. G. & Muckerman, J. T.
Partner: UNT Libraries Government Documents Department
open access

Effects of grids in drift tubes

Description: In 2011, we upgraded a 201 MHz buncher in the proton injector for the alternating gradient synchrotron (AGS) - relativistic heavy ion collider (RHIC) complex. In the buncher we installed four grids made of tungsten to improve the transit time factor. The grid installed drift tubes have 32 mm of inner diameter and the each grid consists of four quadrants. The quadrants were cut out precisely from 1mm thick tungsten plates by a computerized numerically controlled (CNC) wire cutting electrical dis… more
Date: May 20, 2012
Creator: M., Okamura & Yamauchi, H.
Partner: UNT Libraries Government Documents Department
open access

Using a Research Simulator for Validating Control Room Modernization Concepts

Description: The Light Water Reactor Sustainability Program is a research, development, and deployment program sponsored by the United States Department of Energy. The program is operated in close collaboration with industry research and development programs to provide the technical foundations for licensing and managing the long-term, safe, and economical operation of nuclear power plants that are currently in operation. Advanced instrumentation and control (I&C) technologies are needed to support the cont… more
Date: May 1, 2012
Creator: Boring, Ronald L.; Agarwal, Vivek; Persensky, Julius J. & Joe, Jeffrey C.
Partner: UNT Libraries Government Documents Department
open access

Gas-Phase Molecular Dynamics: High Resolution Spectroscopy and Collision Dynamics of Transient Species

Description: This research is carried out as part of the Gas-Phase Molecular Dynamics program in the Chemistry Department at Brookhaven National Laboratory. Chemical intermediates in the elementary gas-phase reactions involved in combustion chemistry are investigated by high resolution spectroscopic tools. Production, reaction, and energy transfer processes are investigated by transient, double resonance, polarization and saturation spectroscopies, with an emphasis on technique development and connection wi… more
Date: May 29, 2012
Creator: Hall, G. E. & Goncharov, V.
Partner: UNT Libraries Government Documents Department
open access

The NIF 4.5-m nTOF Detectors

Description: The first several campaigns of laser fusion experiments at the National Ignition Facility (NIF) included a family of high-sensitivity scintillator/photodetector neutron-time-of-flight (nTOF) detectors for measuring DD and DT neutron yields. The detectors provided consistent neutron yield benchmarks from below 1E9 (DD) to nearly 1E15 (DT). The detectors demonstrated DT yield measurement precisions better than 5%, but the absolute accuracy relies on cross calibration with independent measurements… more
Date: May 7, 2012
Creator: Moran, M. J.; Bond, E. J.; Clancy, T. J.; Eckart, M. J.; Khater, H. Y. & Glebov, V. Y.
Partner: UNT Libraries Government Documents Department
open access

Uranium Enrichment Standards of the Y-12 Nuclear Detection and Sensor Testing Center

Description: The Y-12 National Security Complex has recently fabricated and characterized a new series of metallic uranium standards for use in the Nuclear Detection and Sensor Testing Center (NDSTC). Ten uranium metal disks with enrichments varying from 0.2 to 93.2% {sup 235}U were designed to provide researchers access to a wide variety of measurement scenarios in a single testing venue. Special care was taken in the selection of the enrichments in order to closely bracket the definitions of reactor fuel … more
Date: May 23, 2012
Creator: Cantrell, J.
Partner: UNT Libraries Government Documents Department
open access

Thomson scattering diagnostic for the measurement of ion species fraction

Description: Simultaneous Thomson scattering measurements of collective electron-plasma and ion-acoustic fluctuations have been utilized to determine ion species fraction from laser produced CH plasmas. The CH{sub 2} foil is heated with 10 laser beams, 500 J per beam, at the Omega Laser facility. Thomson scattering measurements are made 4 mm from the foil surface using a 30 J 2{omega} probe laser with a 1 ns pulse length. Using a series of target shots the plasma evolution is measured from 2.5 ns to 9 ns af… more
Date: May 1, 2012
Creator: Ross, J. S.; Park, H. S.; Amendt, A.; Divol, L.; Kugland, N. L.; Rozmus, W. et al.
Partner: UNT Libraries Government Documents Department
open access

A Compact Ring Design with Tunable Momentum Compaction

Description: A storage ring with tunable momentum compaction has the advantage in achieving different RMS bunch length with similar RF capacity, which is potentially useful for many applications, such as linear collider damping ring and predamping ring where injected beam has a large energy spread and a large transverse emittance. A tunable bunch length also makes the commissioning and fine tuning easier in manipulating the single bunch instabilities. In this paper, a compact ring design based on a supercel… more
Date: May 17, 2012
Creator: Sun, Y.
Partner: UNT Libraries Government Documents Department
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