[en] The High Resolution Fly's Eye Detector (HiRes) detects and measures properties of ultrahigh-energy cosmic rays (UHECR). The HiRes detector exploits what is known as the 'air fluorescence' technique that uses the atmosphere as a calorimeter. A brief description of this technique and some recent results of the HiRes detector is given in this paper

[en] A dc triode magnetron has been used to produce freestanding Al/Al + AlN lamellar foils by sputter deposition. The 5-μm-thick foils produced on both flat substrates as well as curved substrates exhibited good specularity as well as excellent mechanical properties. The pulse spacing was varied from none to 100-nm spacing. The yield strength of the material was found to obey the Hall-Petch relation sigma/sub ys/ = 230 + .07/d/sup 1/2/, where sigma/sub ys/ is in MPa. Auger electron Spectroscopy and Secondary Ion Mass Spectroscopy indicate that the large flow stress of 230 MPa must be due to grain refinement of the extended source and not an impurity effect. The result is that limitations of masking found in uniaxial flux sources for curved surfaces can be removed allowing the high quality coating of more general shapes

[en] Numerous samples have been fabricated and analyzed as part of a program to produce soft x-ray dispersion elements for various laboratory applications. The majority of this work has centered around the carbon/tungsten system, although several other low-Z/high-Z pairs have been investigated. This report describes the development of certain vacuum-deposition techniques for fabricating these dispersion elements, based upon results obtained from x-ray reflectivity measurements and Auger depth-profile analysis. The composition of the films is chiefly alternating layers of tungsten carbide and carbon. Excess carbon is introduced during the deposition of the tungsten to ensure that the carbide layer is fully stoichiometric. Layer thickness ranged from approx. 5 to 30 A for the carbide and from approx. 15 to 80 A for the carbon. The reflectivity measurements were made using Fe and Al K_α at grazing incidence. The emphasis in these studies is on the application of surface-analysis results in suggesting modifications to the fabrication process and in evaluating the results such modifications have on the layer stoichiometry, continuity, and periodicity of the dispersion elements so produced

[en] High current photocathodes operating in vacuum environments as high as 8xE-5 torr are being developed at Los Alamos for use in a new generation of linear induction accelerators. We report quantum efficiencies in wide bandgap semiconductors, pure metals, and compound metal surfaces photocathode materials illuminated by ultraviolet laser radiation

[en] We are investigating the deposition and characteristics of metal coatings for use in environments such as the Free Electron Laser where the radiation resistance of metal coatings could prove to be of great benefit. We have concentrated our initial efforts on silver laminate coatings due to the high reflectance of silver at 1 micron wavelength. Our initial laminate coatings have utilized thin layers of titanium oxide to break up the columnar structure of the silver during electron-beam deposition on fused silica substrates. Our initial results on equal coating thickness samples indicate an improvement in damage threshold that ranges from 1.07 to 1.71 at 351 nm

[en] Some electron accelerator applications require bursts of short pulses at high microscopic repetition rates and high peak brightness. A photocathode, illuminated by a mode-locked laser, is well suited to filling this need. The intrinsic brightness of a photoemitter beam is high; experiments are under way at Los Alamos to study the brightness of short bunches with high space charge after acceleration. A laser-illuminated Cs₃Sb photoemitter is located in the first rf cavity of an injector linac. Diagnostics include a pepper-pot emittance analyzer, a magnetic spectrometer, and a streak camera

[en] A dc triode magnetron has been used to produce free-standing Al/Al+AlN lamellar foils by sputter deposition. The 5-μm-thick foils produced on both flat substrates as well as curved substrates exhibited good specularity as well as excellent mechanical properties. The pulse spacing was varied from zero to 100-nm spacing. The yield strength of the material was found to obey the Hall--Petch relation sigma/sub y/s = 230+0.07/d1/2, where sigma/sub y/s is in MPa. Auger electron spectroscopy and secondary ion mass spectroscopy indicate that the large flow stress of 230 MPa must be due to grain refinement of the extended source and not an impurity effect. The result is that limitations of masking found in uniaxial flux sources for curved surfaces can be removed allowing the high quality coating of more general shapes

[en] Experiments have been conducted to measure the quantity of trapped impurities in electron-beam-deposited aluminum films. The depositions were conducted at the 1.3 x 10^-4--1.3 x 10^-2 Pa pressure range with rates varying from a few tenths to 7.0 nm/s. An RGA was used to record the residual gas spectrum before and during all runs. The films were analyzed by sputter profiling and Auger electron spectroscopy. The chief contaminants found were carbon and oxygen. The carbon contaminant tracked the gauge pressure over two orders of magnitude ranging from a few atomic percent to the 500--1000 ppm range. The partial pressures of H₂O, O₂, and other gases were varied during deposition to determine their individual roles in contaminating the films. As a result, a relationship between the residual gas spectrum, and chemical analysis was found

[en] The pulsed gas process (PGP) has been used to produce Al/Al/sub x/O/sub y/

[en] Some electron accelerator applications require bursts of short pulses at high microscopic repetition rates and high peak brightness. A photocathode, illuminated by a mode-locked laser, is well suited to filling this need. The intrinsic brightness of a photoemitter beam is high; experiments are under way at Los Alamos to study the brightness of short bunches with high space charge after acceleration. A laser-illuminated Cs₃Sb photoemitter is located in the first rf cavity of an injector linac. Diagnostics include a pepper-pot emittance analyzer, a magnetic spectrometer, and a streak camera