Download or read book A Novel Method for Modeling the Neutron Time of Flight nTOF Detector Response in Current Mode to Inertial Confinement Fusion Experiments written by and published by . This book was released on 2012 with total page 63 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Neutron and Gamma Time of flight Measurements in Inertial Confinement Fusion Experiments written by Zaarah L. Mohamed and published by . This book was released on 2021 with total page 143 pages. Available in PDF, EPUB and Kindle. Book excerpt: "This work includes the study of various nuclear processes relevant to inertial confinement fusion (ICF) plasmas and big bang nucleosynthesis via experiments performed at the OMEGA laser facility. Neutron and gamma time-of-flight detectors were used to determine various quantities of interest in cryogenic and room temperature implosions. In particular, xylene neutron time-of-flight (nTOF) detectors were used to determine areal densities from backscattered neutrons for OMEGA cryogenic experiments using a forward fit analysis. This analysis was extended to a recently deployed second nTOF line of sight (LOS) on OMEGA. The presence of two nTOF LOS enables a comparison of two measurements to study implosion symmetry, however, these two measurements still leave a lack of coverage around the target chamber which makes it difficult to infer the 3D shape of the areal density. This analysis can easily be extended to additional nTOF lines of sight in the future. The original xylene nTOF detector was also used to infer properties of the 5He ground state and first excited state via a simple wave-function amplitude analysis of neutron spectra from warm TT implosions. These quantities are particularly interesting because of their relationship to the gamma spectrum produced by DT fusion and additionally because the TT neutron spectrum is a background observed in the neutron spectra produced on cryogenic implosions. The ground state mass inferred via forward fit agrees with the accepted value [Audi et al., Nucl. Phys. A 729 (2003)], but the lifetime inferred here is about 70% longer than the accepted value [Wong, Anderson, & McClure, Nucl. Phys. 71 (1965)]. The mass and width of the first excited state were also inferred and compared to previously reported values, though there is a wide spread in the previously reported values. Cherenkov detectors were used to study gamma rays from the reactions D(T,5He)[gamma], H(D,3He)[gamma], and H(T,4He)[gamma] at low energies. The measurements detailed in this work result in a DT gamma-to-neutron branching ratio of (8.42 ł 2.84) × 10-5 measured at a center-of-mass (CM) energy of 19 ł 2 keV. This branching ratio is a factor of 2 larger than the branching ratio previously inferred on an ICF platform [Kim et al., Phys. Rev. C 85 (2012)], however, the error bars on the two measurements overlap. Considering a recent measurement of the DT gamma spectrum [Horsfield et al., Phys. Rev. C. 104 (2021)], the branching ratio measurement detailed in this work also appears to be in agreement with accelerator measurements [Cecil & Wilkinson, Phys. Rev. Lett. 53 (1984); Morgan et al., Phys. Rev. C. 33 (1986)] that isolated the ground state DT gamma. S factors for H(D,3He)[gamma] and H(T,4He)[gamma] were determined at low energies (ECM=16-37 keV). The inferred H(D,3He)[gamma] S factor appears to agree with accelerator data. The H(T,4He)[gamma] S factor inferred from one detector with a relatively high gamma energy threshold appears to be 25-70% larger than an evaluated S factor determined by including accelerator data at higher CM energies [Canon et al., Phys. Rev. C 65 (2002)], however, only two accelerator data points currently exist for comparison at these low energies and these two accelerator data points are in reasonable agreement with the S factors inferred using the high threshold detector as detailed in this work. Another detector with a very low minimum gamma energy threshold was also used to study the H(T,4He)[gamma] S factor. This detector inferred significantly higher values for the H(T,4He)[gamma] S factor, but this particular measurement is thought to be contaminated by detection of neutron-induced gammas from remaining shell material. These time-of-flight gamma measurements require some assumptions concerning the gamma spectrum from each reaction in order to infer branching ratios or S factors. This is not ideal, however, traditional pulse height gamma detection cannot be used for detection of fusion gammas in ICF experiments due to the short time scales involved. Two potential designs are discussed for a true gamma spectrometer intended for operation at ICF facilities"--Pages ix-x.
Download or read book Interpretation of Neutron Time of flight Signals from Current mode Detectors written by and published by . This book was released on 1996 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt: Neutron time-of-flight (nToF) signals from current-mode neutron detectors are often used to determine burn-averaged ion temperature from ICF targets because the spread of the neutron energy distribution is a function of the temperature of the reacting ions. The measured signal will, however, be a convolution of the actual neutron signal, the detector response, and the response of the recording system. In addition, scattered neutrons will arrive at the detector later than unscattered neutrons, further broadening the signal. The ion temperature derived from nToF data depends strongly on the functions used to fit the data or the methods utilized to unfold the neutron energy spectrum. A functional form based on known and measured properties of the detectors is used to fit the integral of the time-of-flight signal, allowing ion temperature derivations from targets with lower neutron yield than previously possible.
Download or read book Analysis of the Neutron Time of Flight Spectra from Inertial Confinement Fusion Experiments 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 diagnostics have long been used to characterize the neutron spectrum produced by inertial confinement fusion experiments. The primary diagnostic goals are to extract the d+t → n+[alpha] (DT) and d+d→ n+3He (DD) neutron yields and peak widths, and the amount DT scattering relative to its unscattered yield, also known as the down-scatter ratio (DSR). These quantities are used to infer yield weighted plasma conditions, such as ion temperature (Tion) and cold fuel areal density. We report on novel methodologies used to determine neutron yield, apparent Tion, and DSR. These methods invoke a single temperature, static fluid model to describe the neutron peaks from DD and DT reactions and a spline description of the DT spectrum to determine the DSR. Both measurements are performed using a forward modeling technique that includes corrections for line-of-sight attenuation and impulse response of the detection system. Lastly, these methods produce typical uncertainties for DT Tion of 250 eV, 7% for DSR, and 9% for the DT neutron yield. For the DD values, the uncertainties are 290 eV for Tion and 10% for the neutron yield.
Download or read book A Preliminary Calibration of Radial Neutron Time Of Flight Detectors on a Dense Plasma Focus written by Jacquelynne Vaughan and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Neutron time-of-flight (nTOF) detectors are commonly used for fast neutron detection on nuclear fusion plasma experiments in high energy density physics. The 4.6-kJ dense plasma focus (DPF) at UC San Diego can generate neutron yields of up to ~108. Two nTOF detectors radially situated at 1.3 m from the DPF are each composed of an EJ-204 plastic scintillator and an Hamamatsu R7724 photomultiplier tube. Several hundred experimental shots have been taken over the course of four different anode types. Of those, 203 shots with neutron data were selected to calibrate both nTOF detectors. A Be-activation detector generates absolute neutron yield data and has a lower detection limit of 1.1·106 neutrons. The latter is used to calibrate the signal areas in the nTOF data, and directly correlate those signal areas with the number of neutrons incident on the detector at its radius from the DPF. This preliminary analysis finds that the two nTOF detectors have approximate efficiencies of 8100 and 1700 photons per DD neutron, respectively. Further analysis can improve the correlation as well as investigate the cross-calibration between the two nTOF detectors more thoroughly.
Download or read book Tests and Calibration of the NIF Neutron Time of Flight Detectors written by and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The National Ignition Facility (NIF) Neutron Time of Flight (NTOF) diagnostic will measure neutron yield and ion temperature in all NIF campaigns in DD, DT, and THD* implosions. The NIF NTOF diagnostic is designed to measure neutron yield from 109 to 2 x 1019. The NTOF consists of several detectors of varying sensitivity located on the NIF at about 5 m and 20 m from the target. Production, testing, and calibration of the NIF NTOF detectors have begun at the Laboratory for Laser Energetics (LLE). Operational tests of the NTOF detectors were performed on several facilities including the OMEGA laser at LLE and the Titan laser at Lawrence Livermore National Laboratory (LLNL). Neutron calibrations were carried out on the OMEGA laser. Results of the NTOF detectors tests and calibration will be presented. *(D = deuterium, T = tritium, H = hydrogen).
Download or read book Multiple Scattering Corrections for the Associated particle Neutron Time of flight Technique written by Allan C. B. Richardson and published by . This book was released on 1969 with total page 72 pages. Available in PDF, EPUB and Kindle. Book excerpt: The computer code, MAGGIE, for the calculation of multiple scattering and sample attenuation in neutron differential cross-section measurements, has been revised and corrected.The particular case of the scattering geometry required by the associated-particle time-of-flight is considered in detail.(Author).
Download or read book Neutron Detector for Fusion Reaction rate Measurements written by and published by . This book was released on 1993 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: We have developed a fast, sensitive neutron detector for recording the fusion reaction-rate history of inertial-confinement fusion (ICF) experiments. The detector is based on the fast rise-time of a commercial plastic scintillator (BC-422) and has a response
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 Use of an On line Computer in Neutron Time of flight Measurements written by H. T. Heaton and published by . This book was released on 1970 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: The paper describes the on-line data handling system at the NBS Electron Linear Accelerator facility as it is used for measuring neutron total cross sections by time-of-flight techniques.(Author).
Download or read book National Ignition Facility NIF Neutron Time of flight nTOF Measurements written by and published by . This book was released on 2010 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: The first three of eighteen neutron time-of-flight (nTOF) channels have been installed at the National Ignition Facility (NIF). The role of these detectors includes yield, temperature, and bang time measurements. This article focuses on nTOF data analysis and quality of results obtained for the first set of experiments to use all 192 NIF beams. Targets produced up to 2 x 101° 2.45-MeV neutrons for initial testing of the nTOF detectors. Differences in neutron scattering at the OMEGA laser facility where the detectors were calibrated and at NIF result in different response functions at the two facilities. Monte Carlo modeling shows this difference. The nTOF performance on these early experiments indicates the nTOF system with its full complement of detectors should perform well in future measurements of yield, temperature, and bang time.
Download or read book Neutron Time of flight Methods written by European-American Nuclear Data Committee and published by . This book was released on 1961 with total page 616 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Detector Distance Selection for ICF Temperature Measurements by Neutron TOF Techniques written by and published by . This book was released on 1990 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fuel ion temperatures for laser-driven, inertial-confinement fusion targets are often determined by neutron time-of-flight (TOF) techniques. The error in the temperature measurement is a minimum at a target-to-detector distance that depends on both target and detector characteristics. The error is dominated by the detector response at shorter distances and by the number of detected neutrons at larger distances. We develop equations that relate the temperature error to the target ion temperature, the number of neutrons detected, target-to-detector distance, and the detector impulse response; and present sample calculations of the error for D-D and D-T plasmas observed by typical Nova neutron TOF detectors. The detector placement is important for minimizing temperature error for target yield below 101° neutrons. 4 refs., 2 figs.
Download or read book Fusion Neutron Measurements for Magnetized Liner Inertial Fusion Experiments on the Z Accelerator written by and published by . This book was released on 2015 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Measurement of Detector Neutron Energy Response Using Time of flight Techniques written by and published by . This book was released on 1973 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book One dimensional Time dependent Integral Neutron Transport for Inertial Confinement Fusion written by Carol S. Aplin and published by . This book was released on 2010 with total page 205 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A New Neutron Time of flight Detector to Measure the MeV Neutron Spectrum at the National Ignition Facility and Its Applications written by and published by . This book was released on 2013 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt:
