Reflection high-energy electron diffraction analysis of polycrystalline films with grain size and orientation distributions

We report a computationally efficient algorithm to calculate reflection high-energy electron diffraction (RHEED) intensities from well-textured, small-grained polycrystalline films in the kinematic limit. We also show how the intensity maps of the spots in a RHEED pattern from such a film can be quantitatively analyzed to determine the film's average grain size, as well as its in-plane orientation and texture distributions. We find that the in-plane orientation and texture distribution widths of these films can be determined to within 1 degree and that the average lateral grain size can be measured to within a fraction of a nanometer after suitable calibration of our technique

Infrared testing of electronic components Final report, 5 Apr. 1965 - 5 Jun. 1966

Infrared radiation nondestructive test technique for electrical/electronic equipmen

Dependence of inner-shell vacancy production upon distance in hard Li-Al collisions

We match the predictions of molecular-dynamics simulations of 1.2 keV and 2.0 keV 7Li+ scattered from Al(100) to observed total Li atom spectra measured by time-of-flight spectroscopy. In doing so we determine the relevant parameters in a simple distance of closest approach model for the probability of production of single and double vacancies in the Li 1s shell during hard Li-Al collisions. In the standard Fano-Lichten model of vacancy production, vacancies are produced with unit probability if the collision is hard enough to force the collision partners past some critical distance of closest approach. We find that such an assumption is insufficient to fit our simulations to experimental observations, and that we must allow for a gradual turning on of the vacancy production probability as the distance of closest approach decreases. The resulting model may be useful in modeling atomic excitation effects in simulations of other ion-impact processes

Simulation of MeV/atom cluster correlations in matter

We present an efficient algorithm able to predict the trajectories of individual cluster constituents as they penetrate relatively thick amorphous targets. Our algorithm properly treats both the intracluster Coulomb repulsion and the collisions between cluster constituents and target atoms. We have compared our simulation predictions to experimental measurements of the distribution of lateral exit velocities, and demonstrated that the in-target Coulomb explosion of 2MeV/atom carbon clusters in carbon foils must be shielded with a screening length of less than 2.5 Å. We also present a simple phenomenological model for the suppression of the exit-side charge of ions in clusters which depends on the enhanced ionization potential that an electron near an ion feels due to the ion’s charged comoving neighbors. By using our simulation algorithm we have predicted the exit correlations of the cluster constituents and verified that the charge suppression model fits the observed charge suppression of ions in clusters to within the experimental uncertainties

Correction and addendum to "The formation of clusters during large sputtering events" [Nucl. Instr. and Meth. B 124 (1997) 31]

We write to note a correction to the event-size specific uncorrelated recombination model presented in "The formation of clusters during large sputtering events" by Hartman et al. [1]. In that paper, Eq. (4). the expression for the phase space density of recombined k-clusters, is in error. Correction affects the relative normalization of k cluster spectra, but not their functional forms. Expressions requiring correction include: the total yield of k-clusters in an event of size N. the absolute yield of k-clusters. and the normalization of the energy and angular spectra

New Capacitive-Array Sensors for Post-Process Cure Verification and NDE of Polymers and Composites

A new capacitive array sensor has been developed for process verification and NDE of polymers and composites. Unlike existing dielectrometer technology, the new sensor incorporates several innovations to maximize sensitivity to material properties while minimizing the effects of temperature, humidity and electromagnetic interference. Conventional dielectric measurement systems require sensors to be embedded within a material and discarded after a single use. Furthermore, conventional sensors are so sensitive to environmental variables that cure monitoring is based solely on changes in the material ionic conductivity; no absolute measure of cure state is possible. The configuration of these new sensors greatly reduces sensitivity to environmental variables and permits external, rather than embedded, measurement making both post-process cure verification and NDE possible. Since the sensor is not discarded, the cost per measurement is greatly reduced

Photometric Analysis of the Optical Counterpart of the Black Hole HMXB M33 X-7

Aims: Study the high-mass X-ray binary X-7 in M33 using broad-band optical data. Methods: We used recently published CFHT r' and i' data for variable stars in M33 to extract the light curve of the optical counterpart of X-7. We combined these data with DIRECT B and V measurements in order to search for an independent optical modulation with the X-ray periodicity. The periodic modulation is modelled with the ellipsoidal effect. We used UBVRr'i' magnitudes of the system to constrain the temperature and radius of the optical component. Results: The optical data revealed a periodicity of 3.4530 +- 0.0014 days, which is consistent with the known X-ray period. Double modulation, which we attributed to ellipsoidal modulation, is clearly seen in four different optical bands. The absolute magnitude in six optical bands is most consistent with a stellar counterpart with 33000 < T_{eff} < 47000 K and 15 < R < 20 R_{\sun}. We modelled the optical periodic modulation and derived the masses of the two components as a function of the orbital inclination and the radius of the stellar component. The resulting mass range for the compact object is 1.3 < M < 23 M_{\sun}. Conclusions: The system is probably a black hole HMXB, similar to Cyg X-1, LMC X-1 and LMC X-3.Comment: Accepted for publication in A&

The planet search programme at the ESO CES and HARPS. IV. The search for Jupiter analogues around solar-like stars

In 1992 we began a precision radial velocity (RV) survey for planets around solar-like stars with the Coude Echelle Spectrograph and the Long Camera (CES LC) at the 1.4 m telescope in La Silla (Chile). We have continued the survey with the upgraded CES Very Long Camera (VLC) and HARPS, both at the 3.6 m telescope, until 2007. The observations for 31 stars cover a time span of up to 15 years and the RV precision permit a search for Jupiter analogues. We perform a joint analysis for variability, trends, periodicities, and Keplerian orbits and compute detection limits. Moreover, the HARPS RVs are analysed for correlations with activity indicators (CaII H&K and CCF shape). We achieve a long-term RV precision of 15 m/s (CES+LC, 1992-1998), 9 m/s (CES+VLC, 1999-2006), and 2.8 m/s (HARPS, 2003-2009, including archive data), resp. This enables us to confirm the known planets around Iota Hor, HR 506, and HR 3259. A steady RV trend for Eps Ind A can be explained by a planetary companion. On the other hand, we find previously reported trends to be smaller for Beta Hyi and not present for Alp Men. The candidate planet Eps Eri b was not detected despite our better precision. Also the planet announced for HR 4523 cannot be confirmed. Long-term trends in several of our stars are compatible with known stellar companions. We provide a spectroscopic orbital solution for the binary HR 2400 and refined solutions for the planets around HR 506 and Iota Hor. For some other stars the variations could be attributed to stellar activity. The occurrence of two Jupiter-mass planets in our sample is in line with the estimate of 10% for the frequency of giant planets with periods smaller than 10 yr around solar-like stars. We have not detected a Jupiter analogue, while the detections limits for circular orbits indicate at 5 AU a sensitivity for minimum mass of at least 1 M_Jup (2 M_Jup) for 13% (61%) of the stars.Comment: 63 pages, 24 figures (+33 online figures), 13 Tables, accepted for publication in A&A (2012-11-13

Effect on Antibiotics in High Fiber Diets on Performance of Growing-finishing Pigs

The majority of the pigs in the Upper Midwest are fed a corn-soybean meal base diet. However, alternative feed ingredients are widely used in some regions. The lower performance, daily gain and efficiency of gain that is sometimes observed when other ingredients are used is often associated with higher fiber content of the diet. The pig has little ability to utilize fibrous materials in the stomach and small intestine where most digestion of feed and absorption of nutrients take place. Microorganisms present in the cecum and large intestine do break down fiber to usable products, but it is assumed that relatively small amounts of these products are absorbed. The effect that antibiotics have on fiber utilization and microbial digestion in the lower digestive tract is largely unknown. The experiment reported herein was designed to evaluate pig performance as affected by fiber level, source of fiber and presence of antibiotics