Monte Carlo Variance Reduction Using Nested Dxtran Spheres

Booth, Thomas E.; Kelley, K; McCready, S. S.

doi:10.13182/nt09-a9303

Cited by 15 publications

(7 citation statements)

References 1 publication

Supporting

Mentioning

Contrasting

Order By: Relevance

“…VR techniques reduced the time required for each simulation, and on average 200 monoenergetic simulations were completed per day on a high performance computing cluster that runs MCNP simulations via a parallel CPU-based architecture. The geometry of each part of the Monte-Carlo simulation was validated against measurements, including the detector and shield [23] and the directional scattering of photons off of the scattering rod using DXTRAN spheres [56] [57] [58]. The DRF was critical in correcting the PHD for the geometry of the experimental setup, and the agreement between the spectra at different CS angles provides confidence in the DRF generation method.…”

Section: Discussionmentioning

confidence: 99%

Measurement of the Energy Spectrum of a 6 MV Linear Accelerator Using Compton Scattering Spectroscopy and Monte Carlo-Generated Corrections

Taneja¹,

Bartol²,

Culberson³

et al. 2020

IJMPCERO

View full text Add to dashboard Cite

Purpose: The energy spectrum of a linear accelerator used for dose calculations is determined during beam commissioning by iteratively adjusting the spectrum and comparing calculated and measured percent depth-dose curves. Direct measurement of the energy spectrum using pulse mode detectors is particularly challenging because of the high-energy, high fluence nature of these beams and limitations of the detector systems. This work implements a Compton scattering (CS) spectroscopy setup and presents detector corrections and spectral unfolding techniques to measure the spectrum of a 6 MV linear accelerator using a pulse mode detector. Methods: Spectral measurements were performed using a Varian Clinac 21EX linear accelerator and a high-purity germanium (HPGe) detector. To reduce fluence to the detector, a custom-built lead shield and a CS spectrometry setup were used. The detector was placed at CS angles of 46˚, 89˚, and 125˚. At each of these locations, a detector response function was generated to account for photon interactions within the experimental geometry. Gold's deconvolution algorithm was used to unfold the energy spectrum. The measured spectra were compared to simulated spectra, which were obtained using an experimentally benchmarked model of the Clinac 21EX in MCNP6. Results: Measurements were acquired and detector response corrections were calculated for all three CS angles. A comparison of spectra for all CS angles showed good agreement with one another. The spectra for all three angles were averaged and showed good agreement with the MCNP6 simulated spectrum, with all points above 400 keV falling within 4%, which was within the uncertainty of the measurement and statistical uncertainty. Conclusions: The measurement of the energy spectrum of a 6 MV linear accelerator using a pulse-mode detector is pre-

show abstract

Section: Discussionmentioning

confidence: 99%

Measurement of the Energy Spectrum of a 6 MV Linear Accelerator Using Compton Scattering Spectroscopy and Monte Carlo-Generated Corrections

Taneja¹,

Bartol²,

Culberson³

et al. 2020

IJMPCERO

View full text Add to dashboard Cite

show abstract

“…Such methods include point tallies and forced flight methods such as Deterministic Transport 6 (DXTRAN), a method built into MCNP6. As such methods have not been proven in deep-penetration problems and instead perform best in voids, 6 they are not discussed further in this review.…”

Section: Iib4 Partially Deterministic Methodsmentioning

confidence: 99%

Review of Hybrid Methods for Deep-Penetration Neutron Transport

Munk

Slaybaugh

2019

Nuclear Science and Engineering

View full text Add to dashboard Cite

Methods for deep-penetration radiation transport remain important for radiation shielding, nonproliferation, nuclear threat reduction, and medical applications. As these applications become more ubiquitous, the need for accurate and reliable transport methods appropriate for these systems persists. For such systems, hybrid methods often obtain reliable answers in the shortest time by leveraging the speed and uniform uncertainty distribution of a deterministic solution to bias Monte Carlo transport and reduce the variance in the solution. This work reviews the state of the art among such hybrid methods. First, we summarize variance reduction (VR) for Monte Carlo radiation transport and existing efforts to automate these techniques. Relations among VR, importance, and the adjoint solution of the neutron transport equation are then discussed. Based on this exposition, the work transitions from theory to a critical review of existing VR implementations in modern nuclear engineering software. At present, the Consistent Adjoint-Driven Importance Sampling (CADIS) and Forward-Weighted Consistent Adjoint-Driven Importance Sampling (FW-CADIS) hybrid methods are the gold standard by which to reduce the variance in problems that have deeply penetrating radiation. The CADIS and FW-CADIS methods use an adjoint scalar flux to generate VR parameters for Monte Carlo radiation transport. Additionally, efforts to incorporate angular information into VR methods for Monte Carlo are summarized. Finally, we assess various implementations of these methods and the degree to which they improve VR for their target applications.

show abstract

“…A second concept is the DXTRAN sphere that allows Monte Carlo particles to move to small regions of a problem that are deemed important. 57 Upgrades were made to the random number generator to allow a longer period and a skip-ahead capability that is required for parallel Monte Carlo calculations. 58 A new method to assess the convergence of Monte Carlo keff eigenvalue calculations was developed, implemented, and tested in the MCNP® code.…”

Section: Iva1 General Monte Carlo Theorymentioning

confidence: 99%

Neutronics Calculation Advances at Los Alamos: Manhattan Project to Monte Carlo

et al. 2021

View full text Add to dashboard Cite

The history and advances of neutronics calculations at Los Alamos during the Manhattan Project through the present is reviewed. We briefly summarize early simpler, and more approximate neutronics methods. We then motivate the need to better predict neutronics behavior through consideration of theoretical equations, models and algorithms, experimental measurements, and available computing capabilities and their limitations. These, coupled with increasing post-war defense needs, and the invention of electronic computing led to the creation of Monte Carlo neutronics transport. As a part of the history, we note the crucial role that the scientific comradery between the great Los Alamos scientists played in the process. We focus heavily on these early developments and the subsequent successes of Monte Carlo and its applications to problems of national defense at Los Alamos. We cover the early methods, algorithms, and computers, electronic and women pioneers, that enabled Monte Carlo to spread to all areas of science.

show abstract

Monte Carlo Variance Reduction Using Nested Dxtran Spheres

Cited by 15 publications

References 1 publication

Measurement of the Energy Spectrum of a 6 MV Linear Accelerator Using Compton Scattering Spectroscopy and Monte Carlo-Generated Corrections

Measurement of the Energy Spectrum of a 6 MV Linear Accelerator Using Compton Scattering Spectroscopy and Monte Carlo-Generated Corrections

Review of Hybrid Methods for Deep-Penetration Neutron Transport

Neutronics Calculation Advances at Los Alamos: Manhattan Project to Monte Carlo

Contact Info

Product

Resources

About