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Multi-strange baryon production in Au+Au collisions at {radical}s{sub NN} = 130 GeV (open access)

Multi-strange baryon production in Au+Au collisions at {radical}s{sub NN} = 130 GeV

The transverse mass spectra and mid-rapidity yields for {Xi}s and {Omega}s plus their anti-particles are presented. The 10% most central collision yields suggest that the amount of multi-strange particles produced per produced charged hadron increases from SPS to RHIC energies. A hydrodynamically inspired model fit to the spectra, which assumes a thermalized source, seems to indicate that these multi-strange particles experience a significant transverse flow effect, but are emitted when the system is hotter and the flow is smaller than values obtained from a combined fit to {pi}, K, p and {lambda}s.
Date: July 30, 2003
Creator: Adams, J.; Adler, C.; Aggarwal, M. M.; Ahammed, Z.; Amonett, J.; Anderson, B. D. et al.
System: The UNT Digital Library
Scene-based Wave-front Sensing for Remote Imaging (open access)

Scene-based Wave-front Sensing for Remote Imaging

Scene-based wave-front sensing (SBWFS) is a technique that allows an arbitrary scene to be used for wave-front sensing with adaptive optics (AO) instead of the normal point source. This makes AO feasible in a wide range of interesting scenarios. This paper first presents the basic concepts and properties of SBWFS. Then it discusses that application of this technique with AO to remote imaging. For the specific case of correction of a lightweight optic. End-to-end simulation results establish that in this case, SBWFS can perform as well as point-source AO. Design considerations such as noise propagation, number of subapertures and tracking changing image content are analyzed.
Date: July 30, 2003
Creator: Poyneer, L A; LaFortune, K & Chan, C
System: The UNT Digital Library
A Multi-Resolution Data Structure for Two-Dimensional Morse Functions (open access)

A Multi-Resolution Data Structure for Two-Dimensional Morse Functions

The efficient construction of simplified models is a central problem in the field of visualization. We combine topological and geometric methods to construct a multi-resolution data structure for functions over two-dimensional domains. Starting with the Morse-Smale complex we build a hierarchy by progressively canceling critical points in pairs. The data structure supports mesh traversal operations similar to traditional multi-resolution representations.
Date: July 30, 2003
Creator: Bremer, P-T; Edelsbrunner, H; Hamann, B & Pascucci, V
System: The UNT Digital Library
Solubility in Binary Solvent Mixtures: Anthracene Dissolved in Alcohol + 2-Methyl-1-butanol Mixtures at 298.2 K (open access)

Solubility in Binary Solvent Mixtures: Anthracene Dissolved in Alcohol + 2-Methyl-1-butanol Mixtures at 298.2 K

Article on solubility in binary solvent mixtures and anthracene dissolved in alcohol + 2-methyl-1-butanol mixtures at 298.2 K.
Date: July 30, 2003
Creator: Monárrez, Cassandra I.; Taylor, Priscilla G.; Tran, Anh M. & Acree, William E. (William Eugene)
System: The UNT Digital Library
Measurement of the indium segregation in InGaN based LEDs with single atom sensitivity (open access)

Measurement of the indium segregation in InGaN based LEDs with single atom sensitivity

In light emitting diodes (LED) consisting of GaN/InGaN/GaN quantum wells (QWs), the exact indium distribution inside the wells of the active region affects the performance of devices. Indium segregation can take place forming small InGaN clusters of locally varying composition. In the past, we used a local strain analysis from single HRTEM lattice images to determine the In composition inside the InGaN QWs with a resolution of 0.5 nm x 0.3 nm. Truly atomic resolution can be pursued by exploitation of intensity dependencies on the atomic number (Z) of the electron exit-wave (EW). In microscopes with sufficient sensitivity, local variations of amplitude and phase are found to be discrete with sample thickness, which allows for counting the number of atoms in each individual column of {approx}0.08 nm diameter. In QW s of {approx}17 percent of average indium concentration it is possible to discriminate between pure Ga columns and columns containing 1, 2, 3, or more In atoms because phase changes are discrete and element specific. The preparation of samples with atomically flat surfaces is a limiting factor for the application of the procedure.
Date: July 30, 2003
Creator: Jinschek, Joerg; Kisielowski, Christian; Van Dyck, Dirk & Geuens, Philippe
System: The UNT Digital Library