Misleadingly Small Full-Width-Half-Maximum, And Other Grazing Incidence Image Features

We have used the new all-sky survey of continuum radio emission at 408 MHz of Haslam et al. (1981 a, b ) to compare the distribution of radio emission in a band along the galactic equator for [ b ] < 20° with the COS-B y-ray distribution of Mayer-Hasselwander et al. (1980). The radio survey has resolution with full width half-maximum (f.w.h.m.) of 51 arc min and the data are brightness temperatures at 20' intervals in galactic coordinates. Such comparisons have been made before (see, for example, Jakel et al. 1975; Paul et al. 1976; Higdon 1979) with earlier y-ray data but this is the first in which the radio data have been in a form allowing a detailed comparison after convolution with the point spread function of the y-ray detector.

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Change in yhe Optical Properties of Sapphire Induced by Ion Implantation

MRS Proceedings ◽

10.1557/proc-504-381 ◽

1997 ◽

Vol 504 ◽

Cited By ~ 5

Author(s):

D. Ila ◽

E. K. Williams ◽

S. Sarkisov ◽

D. B. Poker ◽

D. K. Hensley

Keyword(s):

Optical Properties ◽

Optical Absorption ◽

Full Width Half Maximum ◽

Rutherford Backscattering Spectrometry ◽

Full Width ◽

Half Maximum ◽

Transmission Electron ◽

Before And After ◽

Linear Optical Properties ◽

Average Size

ABSTRACTWe have studied the formation of nano-crystals, after implantation of 2.0 MeV gold, 1.5 MeV silver, 160 keV copper and 160 keV tin into single crystal of A12O3. We also studied the change in the linear optical properties of the implanted Al2O3 before and after subsequent annealing by measuring the increase in resonance optical absorption. Applying Doyle's theory and the results obtained from Rutherford backscattering spectrometry (RBS) as well as the full width half maximum of the absorption band from Optical Absorption Photospectrometry (OAP), we measured the average size of the metallic clusters for each sample after heat treatment. The formation and crystallinity of the nanoclusters were also confirmed using transmission electron microscopy (TEM) technique.

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AMMONO method of BN, AlN and GaN synthesis and crystal growth.

MRS Internet Journal of Nitride Semiconductor Research ◽

10.1557/s1092578300000971 ◽

1998 ◽

Vol 3 ◽

Cited By ~ 37

Author(s):

R. Dwili˜ski ◽

R. Doradzi˜ski ◽

J. Garczy˜ski ◽

L. Sierzputowski ◽

M. Palczewska ◽

...

Keyword(s):

Reaction Rate ◽

Full Width Half Maximum ◽

Full Width ◽

Half Maximum ◽

Helium Temperature ◽

Photoluminescence Spectra ◽

Paramagnetic Resonance ◽

Temperature And Pressure ◽

Supercritical Ammonia ◽

Electron Paramagnetic

Microcrystals of BN, AlN and GaN were obtained by the AMMONO method, in which nitridization of metal occurs in supercritical ammonia, at relatively low temperature and pressure conditions (below 550°C and 5 kbar). The reaction rate was regulated by the amount of mineralizers, i.e. alkali metal amides.All crystals obtained by AMMONO method revealed intense and homogenous luminescence. Significant improvement of the optical properties was observed for crystals grown in the presence of Rare Earth elements. For such GaN crystals, helium temperature photoluminescence spectra were dominated by near-band-gap recombination. Exciton lines were extremely narrow, with full-width half-maximum (FWHM) as low as 1 meV. The concentration of uncompensated shallow donors in AMMONO GaN determined by electron paramagnetic resonance measurements was below 5×1015 cm−3.

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Ultra Thin Flexible Octagonal Metamaterials Absorber

Indonesian Journal of Electrical Engineering and Computer Science ◽

10.11591/ijeecs.v10.i3.pp833-839 ◽

2018 ◽

Vol 10 (3) ◽

pp. 833

Author(s):

H. Hassan ◽

M. Abu

Keyword(s):

Resonance Frequency ◽

Cross Section ◽

Triangular Lattice ◽

Full Width Half Maximum ◽

Metamaterial Absorber ◽

Unit Cell ◽

Basic Unit ◽

Full Width ◽

Half Maximum ◽

Lattice Arrangement

<span lang="IN">An ultra thin flexible octagonal metamaterial absorber on 0.13 mm fastFilm D27 material has been presented in this paper. CST microwave studio was used in designing and simulating the octagonal metamaterial absorber. The flexible octagonal metamaterial absorber was resonated at 10 GHz with highly perfect absorbance of 99.98%. However, Full Width Half Maximum (FWHM) of the absorbance was relatively small 135 MHz affected from the ultra thin substrate used. By using triangular lattice arrangement of the unit cell, the FWHM could be increased to 171 MHz. Besides that, combination of resonating frequencies technique also had increased the FWHM more than 74% increment from basic unit cell with one resonance frequency. The flexibleness of the metamaterial absorber could increase the functionality of the metamaterial absorber to be used in any application especially in reducing radar cross section for stealth application.</span>

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Revisiting Proxima with ESPRESSO

Astronomy and Astrophysics ◽

10.1051/0004-6361/202037745 ◽

2020 ◽

Vol 639 ◽

pp. A77 ◽

Cited By ~ 6

Author(s):

A. Suárez Mascareño ◽

J. P. Faria ◽

P. Figueira ◽

C. Lovis ◽

M. Damasso ◽

...

Keyword(s):

Correlation Function ◽

Radial Velocity ◽

Cross Correlation ◽

Full Width Half Maximum ◽

Cross Correlation Function ◽

Minimum Mass ◽

Full Width ◽

Half Maximum ◽

Stellar Activity ◽

The Cross

Context. The discovery of Proxima b marked one of the most important milestones in exoplanetary science in recent years. Yet the limited precision of the available radial velocity data and the difficulty in modelling the stellar activity calls for a confirmation of the Earth-mass planet. Aims. We aim to confirm the presence of Proxima b using independent measurements obtained with the new ESPRESSO spectrograph, and refine the planetary parameters taking advantage of its improved precision. Methods. We analysed 63 spectroscopic ESPRESSO observations of Proxima (Gl 551) taken during 2019. We obtained radial velocity measurements with a typical radial velocity photon noise of 26 cm s−1. We combined these data with archival spectroscopic observations and newly obtained photometric measurements to model the stellar activity signals and disentangle them from planetary signals in the radial velocity (RV) data. We ran a joint Markov chain Monte Carlo analysis on the time series of the RV and full width half maximum of the cross-correlation function to model the planetary and stellar signals present in the data, applying Gaussian process regression to deal with the stellar activity signals. Results. We confirm the presence of Proxima b independently in the ESPRESSO data and in the combined ESPRESSO+ HARPS+UVES dataset. The ESPRESSO data on its own shows Proxima b at a period of 11.218 ± 0.029 days, with a minimum mass of 1.29 ± 0.13 M⊕. In the combined dataset we measure a period of 11.18427 ± 0.00070 days with a minimum mass of 1.173 ± 0.086 M⊕. We get a clear measurement of the stellar rotation period (87 ± 12 d) and its induced RV signal, but no evidence of stellar activity as a potential cause for the 11.2 days signal. We find some evidence for the presence of a second short-period signal, at 5.15 days with a semi-amplitude of only 40 cm s−1. If caused by a planetary companion, it would correspond to a minimum mass of 0.29 ± 0.08 M⊕. We find that forthe case of Proxima, the full width half maximum of the cross-correlation function can be used as a proxy for the brightness changes and that its gradient with time can be used to successfully detrend the RV data from part of the influence of stellar activity. The activity-induced RV signal in the ESPRESSO data shows a trend in amplitude towards redder wavelengths. Velocities measured using the red end of the spectrograph are less affected by activity, suggesting that the stellar activity is spot dominated. This could be used to create differential RVs that are activity dominated and can be used to disentangle activity-induced and planetary-induced signals. The data collected excludes the presence of extra companions with masses above 0.6 M⊕ at periods shorter than 50 days.

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