Search for a Dark-Matter-Induced Cosmic Axion Background with ADMX.

We report the first result of a direct search for a cosmic axion background (CaB)-a relativistic background of axions that is not dark matter-performed with the axion haloscope, the Axion Dark Matter eXperiment (ADMX). Conventional haloscope analyses search for a signal with a narrow bandwidth, as predicted for dark matter, whereas the CaB will be broad. We introduce a novel analysis strategy, which searches for a CaB induced daily modulation in the power measured by the haloscope. Using this, we repurpose data collected to search for dark matter to set a limit on the axion photon coupling of a CaB originating from dark matter cascade decay via a mediator in the 800-995 MHz frequency range. We find that the present sensitivity is limited by fluctuations in the cavity readout as the instrument scans across dark matter masses. Nevertheless, we suggest that these challenges can be surmounted using superconducting qubits as single photon counters, and allow ADMX to operate as a telescope searching for axions emerging from the decay of dark matter. The daily modulation analysis technique we introduce can be deployed for various broadband rf signals, such as other forms of a CaB or even high-frequency gravitational waves.

Flexible waveguides for Er-YAG laser radiation delivery.

Flexible plastic waveguides (FPW) were devised for the delivery of Er-YAG laser radiation. The FPW characteristics were studied under various conditions. In vitro studies were carried out to explore the drilling procedure on extracted teeth and the FPW-tissue mutual effects. The results which were obtained proved that the FPW as a delivery device might be a substitute hand applicator for the pneumatic turbine for drilling in teeth.

Characterization of hollow fibers for the transmission of infrared radiation.

Plastic hollow fibers were made from plastic tubes covered on the internal wall with a metal layer (a-type) or a metal layer and dielectric layer on top of it (b-type). The CO(2) laser energy transmission through the hollow fiber was measured as a function of the radius of curvature and the coupling lens (focal length at a constant fiber length). The yield of the transmission decreased in subtle curvatures (radius of curvature up to 100 cm) and remained almost constant as the curvature became sharper (down to radius of curvature of 13 cm). For the a-type fibers, the characteristics of attenuation depended on the focal length of the coupling lenses. The energy distribution at the output was measured and mapped. The experimental results showed that the maximum of the energy distribution is asymetrically positioned relative to the center and closer to the internal wall at a smaller bending radius. This was predicted in our previous theoretical calculation. The value of transmitted power attenuation was up to 1.4 dB/m. Maximum power at the output was 30 W, for a fiber of 50-cm length and a cross-sectional diameter of 1.9 mm. These types of hollow fiber have already been used in surgical experiments on dogs.

Nondestructive method for attenuation measurements in optical hollow waveguides.

A new method for characterizing hollow waveguides has been developed in which the laser radiation is coupled into the waveguide hollow bore through an optical fiber. By moving the distal end of the fiber along the waveguide we achieved scanning of the incident radiation in the waveguide at various points on the internal walls. This method can be employed for measuring attenuation without cutback or for detecting point defects on the waveguide's guiding layers.

Ray model for transmission of metallic-dielectric hollow bent cylindrical waveguides.

The problem of transmitting CO(2) laser radiation through metallic or metallic with inner dielectric coating (metallic-dielectric) bent hollow cylindrical waveguides is investigated using a ray model. Computer calculations of transmission as a function of the geometrical dimensions of the waveguide are performed. The coupling of laser radiation at the entrance of the waveguide is also taken into account. The theoretical calculated transmission is compared with previously published experimental data and good agreement is obtained for a large range of curvatures. The devised ray model contributes to a better understanding of the role of the dielectric layer in the metallic-dielectric waveguide, increasing the transmission of the radiation. The calculation of the transmission as a function of the radius of the cross section of the waveguide shows that, for a best metallic-dielectric waveguide, an optimal cross-sectional diameter appears where the transmitted energy is maximum. The method presented will be of value as a tool in the design of hollow cylindrical waveguides.

Experimental surgery on dog's stomach and liver using CO 2 laser plastic hollow fibers: technical method.

Plastic hollow fibers for the transmission of CO 2 laser energy in curved paths were produced by plating the inner surface of plastic tubes with a metal film and dielectric film upon it. These fibers can transmit high power up to 40 W at the outlet, with high transmission yield even through several bendings. A three-dimensional simulator was built to simulate paths in the dog's body and the outlet power was measured. From the achieved data the expected transmitted power during real surgery was appreciated. The fibers were checked for their influence on live tissues of dogs. Incisions were made in the liver and ulcers in the dogs' stomachs were treated. The fibers were inserted into the stomach through the dogs' esophagus. Complete healing was observed after four weeks.

Flexible waveguides for IR laser radiation and surgery applications.

Flexible plastic waveguides were developed to deliver IR radiation, especially at 10.6 microns, which is the CO2 laser radiation wavelength. The waveguide is made from teflon tube with the inner wall coated with a metal layer and a dielectric overlayer. The internal diameter (ID) is 1.0 mm, length 1.0-1.2 m, and the distal tip decreases moderately to ID approximately 0.6 mm. The distal part on the last 10 centimeters is coated externally with a metal layer. Maximum power that can be delivered at the outlet is approximately 30 W and 10.6 x 10(3) W/cm2. This type of waveguide was used in several medical operations to evaluate its cutting characteristics and the resistances to heat reflection from the tissue while operating in orifices containing liquid substances.

Preliminary experiments of possible uses in medicine of novel plastic hollow fibers for transmission of CO2 radiation.

Plastic hollow fibers for the transmission of CO2 laser energy in curved paths were produced by plating the inner surface of plastic tubes with a metal film and dielectric film upon that. These fibers can transmit high power, up to 40 W at the outlet, with high transmission yield even through several bendings. To demonstrate a possible use of the fibers, they were checked for their influence on live tissues of dogs. Incisions were made in the liver, and ulcers in the dogs' stomachs were treated. The fibers were inserted into the stomach through the esophagus. Complete healing was observed after 4 weeks.