Stanley Woolf

Verified

Stanley verified their affiliation via an institutional email.

Learn more

Verified

Stanley verified their affiliation via an institutional email.

Learn more

• Ph.D.
• alumnus at Brown University

The Medium Energy Particle Sensor (MEPS) to be developed as part of the Space Environment Sensor Suite (SESS) for the NPOESS Spacecraft will cover the energy range from 150keV to 10MeV for protons and 50keV to 4 MeV for electrons. It will also include dosimeter capability similar to that of the AMPTEK Compact Environmental Anomaly SEnsor (CEASE). T...

A proton scattering process resulted in damage to one of the Chandra X-ray telescope's focal plane detectors. In this process, incident protons were transmitted, by scattering off the telescope mirrors, to the focal plane. We identify the proton population responsible for the damage and, using a proper grazing angle formalism, we show that the stan...

This paper describes the development of a field portable gamma-ray spectroscopy system based on multielement CdTe detectors. A stack of multiple planar detector elements is used, with each individual element thin enough for good charge transport but with the outputs summed so that the full volume is used. The detector elements are CdTe diodes mount...

A compact particle telescope has been developed to measure highly penetrating protons in space, measuring the differential energy spectrum of protons between 25 and 440 MeV and the integral flux above 440 MeV. This instrument combines new detector materials, an innovative sensor geometry, and a combination of active and passive shielding to obtain...

A coupled leaf/canopy radiative transfer model, LCM2, has been developed with NASA and AFRL funding to investigate the feasibility of detecting spectral signatures from within and under a vegetation canopy. The model is unique in that it features direct radiative transfer coupling between the leaf scattering elements and the canopy reflectance, thr...

The solar cycle dependence of dose rates in the low-altitude "horns" of the outer zone electron belt is examined using data from TSX5/CEASE (solar maximum epoch) and APEX/PASP+ (solar minimum epoch). It is found, after normalizing the dose rates to account for the different shielding geometries, that the ratio of PASP to CEASE dose rates is ~4 for...

This document is a report of the technical progress made during the period 10 Aug. 1999 - 31 July 2000 in the areas of: (1) research and evaluation of particle transport simulation programs for modeling the detection and measurement of space radiation by space-borne sensors; (2) construction of realistic flight sensor computer models; (3) performan...

Space charge and the resulting electric fields accumulate in good insulators during irradiation. In high quality insulators the resulting large electric field will alter the trajectories of high energy electrons. The altered trajectories result in decreased flux of high energy electrons in some regions of material, thus providing enhanced shielding...

In the last several years we have been developing a simplified electron transport model to calculate energy deposition profiles in multilayered structures irradiated by X rays and gamma rays. This model was implemented in a rapidly running algorithm MULTILAYER, for an IBM-compatible personal computer suitable for radiation-hardened electronics and...

A method for calculating dose, charge deposition, current, and electric field profiles across a dielectric slab irradiated by 1-3 MeV electron beams has been developed. The model consists of following the electric field build-up with time. A sequence of Monte Carlo calculations for relativistic electrons moving in an electric field determines the m...

Ionizing collisions occurring in low energy (E⩾E_gap) electron transport in SiO₂ must be considered in floating gate technologies modeling and descriptions of Si/SiO₂ interface degradation. Underlying theories disagree and result in uncertain predictions of impact ionization. Development of a model for scattering...

In this report we describe mathematical analysis, physics research and computer program development for the simulation of charged particle transport in irradiated and non-irradiated solids. The simulation techniques described were used to calculate energy deposition, charge, and current distributions in these solids. The scope of the work included:...

This report describes the development and implementation of numerical methods for the simulation and description of electron and photon transport in layered one-dimensional structures such as metallized semiconductors. The simulations described were used to calculate charge distributions and predict from 1 eV to 20 MeV. The scope of our work includ...

This paper reports the results of Monte Carlo transport calculations for electrons in strong electric fields in silicon dioxide based on new choices for the deformation potential in acoustic phonon scatter and for the ionization threshold. Impact ionization is described on the basis of cross sections derived from many body dielectric theory coupled...

The existing description of hot electron transport in silicon dioxide contains the deficiency that the resulting electron inverse mean free paths and loss rates associated with electron‐acoustic phonon scattering continue to increase in an unphysical way at energies above E gap . One can remove that discrepancy by introducing a pseudo‐potential whi...

The Sn method for solving the Spencer-Lewis equation for electron transport has been extended to treat three-dimensional multiregion problems. The flux continuity condition, which holds when the flux is expressed as a function of path length for single material region problems, is generalized for multiregion problems by reexpressing the flux as a f...

An angular redistribution function for electron scattering based on Goudsmit-Saunderson theory has been implemented in a Monte Carlo electron transport code in the form of a scattering matrix that the authors term SMART (simulating many accumulative Rutherford trajectories). These matrices were originally developed for use with discrete ordinates e...

This report will describe the development and application of numerical methods for predicting dose and variation in multi-layered structures due to x-rays and gamma rays and the charge build-up in dielectrics due to electron beam irradiation. The scope our work included: development and implementation of: 1) discrete ordinates electron transport ca...

A Monte Carlo program, using single scatter cross sections and phonon scattering theory, was developed to analyze elastic and inelastic scattering of electrons and to obtain electron and hole distributions in insulators subjected to electron bombardment. The design of the Monte Carlo Algorithm is based on a simple electron transport model-a collisi...

Electron beam dose profiles have been calculated using a multigrouip, discrete ordinates solution of the Spencer-Lewis electron transport equation. This was accomplished by introducing electron transport crosssections into the ONETRAN code in a simple manner. Our purpose is to "benchmark" this electron transport model and to demonstrate its accurac...

The Spencer-Lewis equation for kilovolt electron transport in two dimensions was solved using a discrete ordinates, diamond difference method. Calculations of dose profiles in 2-D were made for 200 keV electrons normally and isotropically incident on aluminum and are compared with ACCEPT Monte Carlo calculations. Isodose contour plots are also pres...

The use of analytic first collision sources can greatly improve the accuracy of neutral particle S/sub N/ calculations. For electrons, because of the strong anisotropy of the electron scattering kernel, many collisions are required before the flux from a beam source is smooth enough to lend itself to practical numerical treatment. Thus the use of a...

An electron transport solver has been developed based on a streaming ray (SR) solution to the Spencer-Lewis equation. Several special numerical techniques were used to make the algorithm fast and accurate. These include 1. an efficient routine for simulating energy loss straggling 2. use of extended-transport-corrected and Fokker-Planck equivalent...

The ONETRAN code was used to compute dose profiles near gold/aluminum interfaces for photon energies from 100 to 1250 keV. Weighted by a four component photon spectrum obtained from a least-squares fit to measured dose distribution data, the calculated profiles agree closely with Cobalt-60 ionization chamber data.

Two discrete ordinates methods, the S/sub ETA/ and streaming ray methods, are applied to electron transport problems. Calculational results in the form of energy deposition profiles are compared with those obtained by the method of moments for the case of a 200-keV plane perpendicular source embedded in infinite aluminum. In a second set of calcula...

Calculations were made of dose and displacement damage rate profiles in GaAs and Si for electron beams and gamma rays. Electron flux energy spectra as a function of position were calculated using the ONETRAN code. Displacement cross-sections were calculated by integrating the Mott cross section using threshold energies of 10 eV for GaAs and 12.9 eV...

An efficient electron transport discrete ordinates code must be able to model extremely forward peaked scattering (L > 100) using relatively few (typically 12 ) discrete directions. Fokker-Planck techniques and the Boltzmann approach with the extended transport correction have been reasonably successful. However, the former method gives an inaccura...

Calculations of scattered photon spectra in concrete rooms are made, by means of the Monte Carlo method, for Co-60 sources of the type used in irradiation testing of electronic devices. It is found that the scattered photon spectrum shape is heavily dependent on the location of source and target, and that in devices where dose enhancement can occur...

Photon spectra in various ⁶⁰Co irradiation cells are compared, and the filtering effects of shielding materials on the spectra are examined. The impact of scattered ⁶⁰Co photons on radiation testing of electronic devices is discussed, along with the resulting dose enhancement factors for Au-metallized devices. Standard dosimet...

Electric fields due to irradiation by 2-20 keV electrons in polyethylene terephthalate are calculated. Peak fields exceeding 106 V/cm are predicted and would be expected in nearly all highly insulating polymers. Secondary bremsstrahlung and x-ray effects are investigated. Electrode current as a function of time is calculated during constant intensi...

Charge deposition as a function of depth in electron irradiated polymeric C6H9O is determined. Monoenergetic beams at 0.4, 0.6, 0.8, 1.0, 1.2 and 1.4 MeV are used and results are compared to Monte Carlo simulation.

A new particle transport theory method has been developed for application in particle streaming and shielding calculations. The method is similar to the SN technique in that discrete directions are used, and the transport medium is divided into spatial mesh cells. However, in addition to the spatial mesh, the entire medium is overlaid with a series...

In very large scale integrated circuits (VLSI), multiple layers of different atomic number materials are separated by a few microns or less. When this type of structure is irradiated with high energy gamma rays, the transport of energy by energetic electrons must be taken into account. By comparing Monte Carlo calculations with experimental data, w...

Scitation is the online home of leading journals and conference proceedings from AIP Publishing and AIP Member Societies

In this report, we will describe the techniques and computer programs developed to analyze various problems. The scope of our work extended into a vareity of technical areas. A program was written to design a filter for analog-to-digital converted radar signals. The problem of low energy electron transport in irradiated solids was studied via four...

A variation of the method of invariant imbedding can be applied to a class of particle-transport problems for which the average energy of a particle can be closely correlated to the number of collisions it has undergone in the course of transport through a scattering medium. A method for calculating emergent n'th scattered particle currents from sc...

A novel, simplified approach to particle transport in slabs is given. The number of particles transmitted and reflected by a slab of finite thickness is obtained as a function of the number of collisions the particles receive. This 'orders-of-scattering' solution is facilitated by an invariant imbedding approach which leads to a set of integral rec...

A method for calculating emergent n-th scattered particle currents from scattering media is developed which combines an orders-of-scattering formulation with the invariant imbedding method. The final expressions obtained for these currents assume the form of coupled integral recursion relations expressing the interdependence of the currents of the...

Contents: Interactive simulation of a dynamic radar environment; Low energy electron transport Boltzmann equation treatment; Low energy electron transport - Monte Carlo treatment; High energy electron transport; Fourier spectroscopy; Reflection from an idealized atmospheric wave; Sound propagation in piezoelectric crystals - the relationship betwee...

An approach to neutron collimator design is suggested in which wall-emergent neutrons are forced to reflect from the surface of each (tapered) segment beyond the point of emergence. Designs of this type, together with a suggested design for a proposed neutron-neutron scattering experiment, are compared in simple Monte Carlo and analytic studies.

The theoretical bases of a land-surface-burst nuclear-cloud-rise model and details of development from the theoretical model of the DELFIC Cloud Rise Module computer program are presented. By use of this dynamic cloud rise model, histories of the rise, growth, temperature, and composition of the cloud are computed throughout virtually the entire pe...

This report describes the development and application of numerical methods for predicting dose and variation in multi-layered structures due to x rays and gamma rays and the charge buildup in dielectrics due to electron-beam irradiation. The scope of the work included: development and implementation of: 1) discrete-ordinates electron-transport calc...

In this study, we have calculated the energy spectrum of electron flux near the interface between two semi-infinite media for a uniform isotropic source of electrons in one of the media. The following cases of medium 1/medium 2 (with denoting the side containing the electron source) were studied: Al/Al, Au/Al, Al/Au, and Au/Au for several source en...

Calculations were performed by the Monte Carlo method to determine the dose at various detector locations behind a vertical barrier and below an adjacent horizontal barrier. Results were obtained, using two different Monte Carlo approaches, for a 1.25-MeV simulated ground source incident on 60, 40, and 20 psf of concrete. The results of the Monte C...

Calculations were performed by the Monte Carlo method to determine the dose at various positions behind parallel barriers (circular or rectangular). Also, calculations were made for a blockhouse geometry. The results were obtained for a 1.25 MeV plane monodirectional source incident on 20.5, 41.0, and 61.5 psf of iron. Comparisons were made with ro...