A basic lock-in amplifier experiment for the undergraduate laboratory

We describe a basic experiment for the undergraduate laboratory that demonstrates aspects of both, the science and the art of precision electronic measurements. The essence of the experiment is to measure the resistance of a small length of brass-wire to high accuracy using a simple voltage divider and a lock-in amplifier. By performing the measurement at different frequencies and different drive currents, one observes various random noise sources and systematic measurement effects

Focused-ion-beam-induced deposition of superconducting nanowires

Superconducting nanowires, with a critical temperature of 5.2 K, have been synthesized using an ion-beam-induced deposition, with a Gallium focused ion beam and Tungsten Carboxyl, W(CO)6, as precursor. The films are amorphous, with atomic concentrations of about 40, 40, and 20 % for W, C, and Ga, respectively. Zero Kelvin values of the upper critical field and coherence length of 9.5 T and 5.9 nm, respectively, are deduced from the resistivity data at different applied magnetic fields. The critical current density is Jc= 1.5 10^5 A/cm2 at 3 K. This technique can be used as a template-free fabrication method for superconducting devices.Comment: Accepted for publication in Applied Physics Letter

Soils and feasibility investigation, Kaopa subdivision unit 3B, Kailua, Oahu, Hawaii

Content: report, boring logs, consolidation test report, and preliminary grading planLone Star Hawai

Foundation investigation -- proposed apartment buildings, Kaneohe, Hawaii

tax map key: 4-5-50-26Sections: structural considerations, site conditions, field exploration, soil conditions, recommendations, limitations, laboratory testing, boring logs, consolidation test reports, and site plan.Walter Zane Reality Corp

Addendum recommendations -- Kaopa Unit 3C, Kailua, Oahu, Hawaii

Includes laboratory test results, moisture content, and grading utility plan.Lone Star Hawaii, Inc

Compacted fill report -- Kau Hale Aupuni O' Kuliouou, Kuliouou, Oahu, Hawaii

tax map key: 3-8-10: 5, 6, and 7, and 3-8-11: 1Includes density test results and grading plans.KVA-HD&C Joint Ventur