Download or read book Measuring the Absolute DT Neutron Yield Using the Magnetic Recoil Spectrometer at OMEGA and the NIF written by and published by . This book was released on 2012 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: A Magnetic Recoil Spectrometer (MRS) has been installed and extensively used on OMEGA and the National Ignition Facility (NIF) for measurements of the absolute neutron spectrum from inertial confinement fusion (ICF) implosions. From the neutron spectrum measured with the MRS, many critical implosion parameters are determined including the primary DT neutron yield, the ion temperature, and the down-scattered neutron yield. As the MRS detection efficiency is determined from first principles, the absolute DT neutron yield is obtained without cross-calibration to other techniques. The MRS primary DT neutron measurements at OMEGA and the NIF are shown to be in excellent agreement with previously established yield diagnostics on OMEGA, and with the newly commissioned nuclear activation diagnostics on the NIF.
Download or read book The Magnetic Recoil Spectrometer for Measurements of the Absolute Neutron Spectrum at OMEGA and the NIF written by and published by . This book was released on 2013 with total page 43506 pages. Available in PDF, EPUB and Kindle. Book excerpt: The neutron spectrum produced by deuterium-tritium (DT) inertial confinement fusion implosions contains a wealth of information about implosion performance including the DT yield, iontemperature, and areal-density. The Magnetic Recoil Spectrometer (MRS) has been used at both the OMEGA laser facility and the National Ignition Facility (NIF) to measure the absolute neutron spectrum from 3 to 30 MeV at OMEGA and 3 to 36 MeV at the NIF. These measurements have been used to diagnose the performance of cryogenic target implosions to unprecedented accuracy. Interpretation of MRS data requires a detailed understanding of the MRS response and background. This paper describes ab initio characterization of the system involving Monte Carlo simulations of the MRS response in addition to the commission experiments for in situ calibration of the systems on OMEGA and the NIF.
Download or read book First Measurements of the Absolute Neutron Spectrum Using the Magnetic Recoil Spectrometer MRS at OMEGA written by and published by . This book was released on 2008 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: A new type of neutron spectrometer, called a Magnetic Recoil Spectrometer (MRS), has been built and implemented at the OMEGA laser facility [T.R. Boehly. D.L. Brown, R.S. Craxton et al., Opt. Commun. 133, 495 (1997)] for absolute measurements of the neutron spectrum in the range 6 to 30 MeV, from which fuel areal density ([rho]R), ion temperature (T{sub i}) and yield (Y{sub n}) can be determined. The results from the first MRS measurements of the absolute neutron spectrum are presented. In addition, measuring [rho]R at the National Ignition Facility (NIF) [G.H. Miller, E.I. Moses and C.R. Wuest, Nucl. Fusion 44, S228 (2004)] will be essential for assessing implosion performance during all stages of development from surrogate implosions to cryogenic fizzles and ignited implosions. To accomplish this, we are also developing an MRS for the NIF. As much of the R & D and instrument optimization of the MRS at OMEGA is directly applicable to the MRS at the NIF, a description of the MRS design on the NIF is discussed as well.
Download or read book Isotopes Advances in Research and Application 2011 Edition written by and published by ScholarlyEditions. This book was released on 2012-01-09 with total page 211 pages. Available in PDF, EPUB and Kindle. Book excerpt: Isotopes: Advances in Research and Application: 2011 Edition is a ScholarlyEditions™ eBook that delivers timely, authoritative, and comprehensive information about Isotopes. The editors have built Isotopes: Advances in Research and Application: 2011 Edition on the vast information databases of ScholarlyNews.™ You can expect the information about Isotopes in this eBook to be deeper than what you can access anywhere else, as well as consistently reliable, authoritative, informed, and relevant. The content of Isotopes: Advances in Research and Application: 2011 Edition has been produced by the world’s leading scientists, engineers, analysts, research institutions, and companies. All of the content is from peer-reviewed sources, and all of it is written, assembled, and edited by the editors at ScholarlyEditions™ and available exclusively from us. You now have a source you can cite with authority, confidence, and credibility. More information is available at http://www.ScholarlyEditions.com/.
Download or read book An Improved Method for Measuring the Absolute DD Neutron Yield and Calibrating Neutron Time of flight Detectors in Inertial Confinement Fusion Experiments written by Caleb Joseph Waugh and published by . This book was released on 2014 with total page 226 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since the establishment of nuclear physics in the early 1900's and the development of the hydrogen bomb in the 1950's, inertial confinement fusion (ICF) has been an important field in physics. Funded largely though the U.S. National Nuclear Security Agency (NNSA), the Laboratory for Laser Energetics (LLE), Sandia National Laboratories (SNL) and Lawrence Livermore National Laboratory (LLNL) have advanced ICF as a platform for stockpile stewardship and weapons physics, but also have contributed to basic science in high energy density regimes and for pursuing fusion an energy source. One of the primary goals of the ICF research program is to produce a thermonuclear burn in an ICF capsule where the power balance of the reaction is net positive. This criterion is often referred to as ignition. One of the most common metrics for gauging progress towards ignition in an ICF implosion is the ITFX parameter (similar to the Lawson Criterion) and is primarily a function of the implosion areal density (pR) and fusion yield. An ITFX value greater than one indicates net energy production. In deuterium/tritium fuel mixtures the yield is determined by measuring the reactant 14.0 MeV neutrons. Subsequently, the ability to obtain highly accurate absolute neutron yield measurements is vital to determining the ITFX and hence progress toward ignition. Although ignition implosions all use deuterium/tritium fuel mixes, other capsule fuel mixes such as pure deuterium and deuterium/helium 3 are also used to improve understanding of capsule performance. At the LLE and LLNL, neutron time-of-flight (nTOF) detectors routinely measure the absolute neutron yield from laser-driven ICF implosions. Although originally calibrated through a series of cross-calibrations with indium and copper neutron activation systems, an alternative method has been developed for measuring the DDn yield that provides a more accurate calibration by directly calibrating nTOF in situ to CR-39 range filter (RF) proton detectors. A neutron yield can be inferred from the CR-39 RF proton measurement since the DD proton and DD neutron branching ratio is well characterized and close to unity. By obtaining highly accurate DDp yields from a series of exploding pusher campaigns on OMEGA, an excellent absolute DDn yield measurement was obtained and used to calibrate the 3m nTOF detector. Data obtained suggest the existing OMEGA nTOF calibration coefficient to be low by 9.0 1.5 % based on the inferred CR-39 DD neutron yield. In addition, comparison across multiple exploding pusher campaigns indicate that significant reduction in charged particle flux anisotropies can be achieved on shots where capsule bang time occurs significantly (on the order of 500ps) after the end of the laser pulse. This is important since the main source of error in the RF DDp yield measurement is due to particle flux anisotropies. Results indicate that the CR-39 RF/nTOF in situ calibration method can serve as a valuable platform for measuring the DDn yield from ICF implosions and for calibrating and reducing the uncertainty of calibration coefficients of nTOF detector systems on OMEGA and other larger facilities such as the National Ignition Facility (NIF).
Download or read book A Method for in Situ Absolute DD Yield Calibration of Neutron Time of flight Detectors on OMEGA Using CR 39 based Proton Detectors written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Neutron time of flight (nTOF) detectors are used routinely to measure the absolute DD neutron yield at OMEGA. To check the DD yield calibration of these detectors, originally calibrated using indium activation systems, which in turn were cross-calibrated to NOVA nTOF detectors in the early 1990s, a direct in situ calibration method using CR-39 range filter proton detectors has been successfully developed. By measuring DD neutron and proton yields from a series of exploding pusher implosions at OMEGA, a yield calibration coefficient of 1.09 ± 0.02 (relative to the previous coefficient) was determined for the 3m nTOF detector. In addition, comparison of these and other shots indicates that significant reduction in charged particle flux anisotropies is achieved when bang time occurs significantly (on the order of 500 ps) after the trailing edge of the laser pulse. This is an important observation as the main source of the yield calibration error is due to particle anisotropies caused by field effects. The results indicate that the CR-39-nTOF in situ calibration method can serve as a valuable technique for calibrating and reducing the uncertainty in the DD absolute yield calibration of nTOF detector systems on OMEGA, the National Ignition Facility, and laser megajoule.
Download or read book Absolute Measurement of DT Neutron Yield on the National Ignition Facility written by and published by . This book was released on 2011 with total page 21 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Problem of Measuring the Absolute Yield of 14 mev Neutrons by Means of an Alpha Counter written by and published by . This book was released on 1959 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Neutron Spectral Measurements by Magnetic Analysis of Recoil Protons written by C. M. Cialella and published by . This book was released on 1967 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: The spectral distribution of neutrons from the TRIGA Mark F Reactor at the U.S. Army Harry Diamond Laboratories was measured with a magnetic neutron spectrometer. This instrument is a broad range, low deflection spectrometer which utilizes the magnetic analysis of protons recoiling from a thin polyethylene radiator. The spectrometer will cover an energy range from 0.5 to 17 MeV with a single magnetic field setting. The spectrometer has an array of 40 solid-state detectors placed along the focal line and includes the associated electronics. This provides the instrument with the capability of measuring the entire spectrum from either pulsed or steady state sources. Measurements of the neutron spectrum with the reactor in the steady state mode were made using four radiators of different thicknesses. Measurements were made of the power output of the reactor in the pulse mode. The width of the reactor pulse was measured to be 11.0 ms (full width at half maximum). (Author).
Download or read book Measurement of Neutron Flux and Spectra for Physical and Biological Applications written by National Committee on Radiation Protection and Measurements (U.S.) and published by . This book was released on 1960 with total page 104 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Measurement of Neutron Flux and Spectra for Physical and Biological Applications written by National Committee on Radiation Protection and Measurements (U.S.) and published by . This book was released on 1960 with total page 104 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Absolute Measurement of Thermal Neutron Density written by H. L. Anderson and published by . This book was released on 1947 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Study of Neutron Scattering in the NIF Chamber and Use of Neutron Activation as a Yield Diagnostic Tu011 5 written by M. Tobin and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: One of the planned core neutron diagnostics for NIF will use material activation to aid in determining information about target neutron yields. While this technique was routinely used on Nova and is in use today on Omega, the substantially larger chamber size and neutron yields for NIF raise several new issues for this technique. The effect of neutron scattering, due to the larger amount of entrant equipment inside the chamber, and more importantly, scattering inside the NIF target itself, is shown to be a significant effect. The appropriate location of the counting room to analyze activated samples that is sufficiently protected from neutron fluences is discussed. There are no significant safety issues related to sample handling when using In and Cu for short durations (minutes). We recommend placement and thickness of Cu samples based on neutron yield.
Download or read book On the Absolute Calibration of a DT Fusion Neutron Yield Diagnostic written by and published by . This book was released on 2012 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Measurement of Neutron Flux and Spectra for Physical and Biological Applications written by United States. National Committee on Radiation Protection and Measurements and published by . This book was released on 1960 with total page 102 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Thick Target D T Neutron Yield Measurements Using Metal Occluders of Scandium Titanium Yttrium Zirconium Gadolinium Erbium Hafnium and Tantalum at Energies from 25 to 200 KeV written by and published by . This book was released on 1990 with total page 22 pages. Available in PDF, EPUB and Kindle. Book excerpt: Deuterium-Tritium (D-T) neutron yields from thick films of scandium, titanium, yttrium, zirconium, gadolinium, erbium, hafnium, and tantalum were measured by the associated particle technique using the 200-keV accelerator at the Pinellas Plant. The neutron yields were measured for all targets at energies from 25 to 200 keV in 5-keV steps with an average uncertainty of ±6.8%. Tabulated results are presented with yield versus energy curves for each target. Yield curves for D-D neutrons from earlier measurements are also presented with the D-T neutron yield curves. Good fits to the data were found for both D-D and D-T with theoretical calculations that were adjusted by smooth functions of the form: A0 + A1E + A2E2. The results of the fits strongly suggest that disagreement between measurement and theory is due mainly to inaccuracies in currently available stopping power data. Comparisons with earlier theoretical calculations for titanium and erbium are also presented. 27 refs., 10 figs., 4 tabs.
Download or read book Measurements of DT and DD Neutron Yields by Neutron Activation on TFTR written by and published by . This book was released on 1995 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: A variety of elemental foils have been activated by neutron fluence from TFTR under conditions with the DT neutron yield per shot ranging from 1012 to over 1018, and with the DT/(DD+DT) neutron ratio varying from 0.5% (from triton burnup) to unity. Linear response over this large dynamic range is obtained by reducing the mass of the foils and increasing the cooling time, all while accepting greatly improved counting statistics. Effects on background gamma-ray lines from foil-capsule-material contaminants, and the resulting lower limits on activation foil mass, have been determined. DT neutron yields from dosimetry standard reactions on aluminum, chromium, iron, nickel, zirconium, and indium are in agreement within the ±9% (one-sigma) accuracy of the measurements; also agreeing are yields from silicon foils using the ACTL library cross-section, while the ENDF/B-V library has too low a cross-section. Preliminary results from a variety of other threshold reactions are presented. Use of the 115In(n.n(prime)) {sup 115m}In reaction (0.42 times as sensitive to DT neutrons as DD neutrons) in conjunction with pure-DT reactions allows a determination of the DT/(DD+DT) ratio in trace tritium or low-power tritium beam experiments.
