The source fluence distribution of terrestrial gamma ray flashes (TGFs) has been extensively discussed in recent years, but few have considered how the TGF fluence distribution at the source, as estimated from satellite measurements, depends on the distance from satellite foot point and assumed production altitude. As the absorption of the TGF photons increases significantly with lower source a...

Submitted for the MAR07 Meeting of The American Physical Society Confounding Effect of Spot-Size on the Wavelength-Dependence of Tissue Ablation Metrics1 M. SHANE HUTSON, GILMA ADUNAS, YAOWU XIAO, Vanderbilt University — Tunable free-electron lasers have been used in several previous studies to investigate the mid-IR wavelength-dependence of tissue ablation. These studies gave conflicting resul...

We present a temperature and fluence dependent Ultrafast X-Ray Diffraction study of a laser-heated antiferromagnetic dysprosium thin film. The loss of antiferromagnetic order is evidenced by a pronounced lattice contraction. We devise a method to determine the energy flow between the phonon and spin system from calibrated Bragg peak positions in thermal equilibrium. Reestablishing the magnetic ...

We investigate picosecond laser ablation of metals using a hybrid simulation scheme. Laser energy input into the electron system and heat conduction within it are modeled using a finite-difference scheme for solving the heat conduction equation. Atom motion in the near-surface part ~72 nm! of the sample is modeled using molecular dynamics. Energy transfer between the electronic and atomic subsy...

High-energy terahertz pulses are produced by optical rectification (OR) in organic crystals 4-dimethylamino-N-methyl-4-stilbazolium tosylate (DAST) and 4-N, N-dimethylamino-4'-N'-methyl-stilbazolium 2,4,6-trimethylbenzenesulfonate (DSTMS) by a Ti:sapphire amplifier system with 0.8 μm central wavelength. The simple scheme provides broadband spectra between 1 and 5 THz, when pumped by a collimate...

Copper iodide (CuI) is a promising semiconductor with many potential applications in the fields of opto-electronics, solar cells, photodetectors and thermoelectric for energy harvesting. 30 keV 32S+ ions were implanted fluences between 5.0 × 1014 1.1 1016 cm−2 which results 0.3–5.5 at% peak sulfur concentration at an average depth ~ nm. Sulfur implantation increased electrical conductivity by u...

Fluence-response relationships of phototropism in light- and dark-grown buckwheat (Fagopyrum esculentum Moench.) were compared using systematically varied fluence rates and irradiation times of unilateral monochromatic blue light. Etiolated seedlings respond to most fluence rates in a tri-phasic manner. Phase one differs from classic first positive in that reciprocity is not observed and the pe...

In this first paper of a two-paper series, we present a method for 10 optimizing the dynamic delivery of fluence maps in radiation therapy. For a given fluence map and a given delivery time, the optimization of the leaf trajectories of a multi-leaf collimator to approximately form the given fluence map is a nonconvex optimization problem. Its general solution has not been addressed in the liter...

Dynamic changes in internal light fluence were measured during interstitial laser heating of tissue phantoms and ex vivo bovine liver. In albumen phantoms, the results demonstrate an unexpected rise in optical power transmitted approximately I cm away from the source during laser exposure at low power (0.5-1 W), and a decrease at higher powers (1.5-2.5 W) due to coagulation and possibly charrin...

Fluence-response curves for the induction of seed germination after 24 hours pretreatment at 35 degrees C of Rumex obtusifolius and Arabidopsis thaliana show two phases of response: (a) a very low fluence-response (10(-4) - 10(-1) micromoles per square meter) and (b) a low fluence-response (1 - 10(3) micromoles per square meter).