A comparative test of the air consumption of rock drills

The aim of this thesis is an attempt to determine the relative efficiency, of four standard types of rock drills, as to air consumption. The air consumption was based upon the cubic inch of rock drilled by each machine. The orifice method of measurement being utilized, in connection with the exhaust to determine the desired consumption --page 1

A VISUAL STUDY OF THE CORROSION OF DEFECTED ZIRCALOY-2-CLAD FUEL SPECIMENS BY HOT WATER

The failure of defected Zircaloy-2-clad uranium and uranium -2 wt.% zircorium fuel specimens in high-purity high-pressure water at 200 to 345 deg C was observed in a windowed antcclave. Time-lapse color motion pictures were taken to provide a record of the progressive changes ending in the complete disintegration of the core material in the specimens. Continuous measurement of the pressure increase caused by accumulation of hydrogen served to monitor the progress of the reaction when clouding of the water by corrosion products made visual observation impossible. The nature of the attack of all specimens was similar, although the time at which different stages occurred varied. Following an induction period, the first evidence of attack was the slow formation of a blister in the cladding area surrounding the defect. Eventually, a copions evolution of hydrogen occurried at the base of the swollen area. In general, a crack could be seen in the cladding at this stage. Catastrophic failure of the specimen followed swiftly. The time required for each phase of the reaction was reduced as the temperature was raised. Initial swelling occurred after about 24 min at 345 deg C but only after 8 hr at 200 deg C. Diffusion-treated uranium2 wt.% zirconium-cored specimens were most resistant to attack. Specimens with beta-treated water-quenched natural-uranium cores were least resistant (auth

Enabling Large Focal Plane Arrays Through Mosaic Hybridization

We have demonstrated advances in mosaic hybridization that will enable very large format far-infrared detectors. Specifically we have produced electrical detector models via mosaic hybridization yielding superconducting circuit patbs by hybridizing separately fabricated sub-units onto a single detector unit. The detector model was made on a 100mm diameter wafer while four model readout quadrant chips were made from a separate 100mm wafer. The individually fabric.ted parts were hybridized using a Suss FCI50 flip chip bonder to assemble the detector-readout stack. Once all of the hybridized readouts were in place, a single, large and thick silicon substrate was placed on the stack and attached with permanent epoxy to provide strength and a Coefficient of Thermal Expansion match to the silicon components underneath. Wirebond pads on the readout chips connect circuits to warm readout electronics; and were used to validate the successful superconducting electrical interconnection of the model mosaic-hybrid detector. This demonstration is directly scalable to 150 mm diameter wafers, enabling pixel areas over ten times the area currently available

The Primordial Inflation Polarization Explorer (PIPER)

The Primordial Inflation Polarization Explorer (PIPER) is a balloon-borne cosmic microwave background (CMB) polarimeter designed to search for evidence of inflation by measuring the large-angular scale CMB polarization signal. BICEP2 recently reported a detection of B-mode power corresponding to the tensor-to-scalar ratio r = 0.2 on ~2 degree scales. If the BICEP2 signal is caused by inflationary gravitational waves (IGWs), then there should be a corresponding increase in B-mode power on angular scales larger than 18 degrees. PIPER is currently the only suborbital instrument capable of fully testing and extending the BICEP2 results by measuring the B-mode power spectrum on angular scales $\theta$ = ~0.6 deg to 90 deg, covering both the reionization bump and recombination peak, with sensitivity to measure the tensor-to-scalar ratio down to r = 0.007, and four frequency bands to distinguish foregrounds. PIPER will accomplish this by mapping 85% of the sky in four frequency bands (200, 270, 350, 600 GHz) over a series of 8 conventional balloon flights from the northern and southern hemispheres. The instrument has background-limited sensitivity provided by fully cryogenic (1.5 K) optics focusing the sky signal onto four 32x40-pixel arrays of time-domain multiplexed Transition-Edge Sensor (TES) bolometers held at 140 mK. Polarization sensitivity and systematic control are provided by front-end Variable-delay Polarization Modulators (VPMs), which rapidly modulate only the polarized sky signal at 3 Hz and allow PIPER to instantaneously measure the full Stokes vector (I, Q, U, V) for each pointing. We describe the PIPER instrument and progress towards its first flight.Comment: 11 pages, 7 figures. To be published in Proceedings of SPIE Volume 9153. Presented at SPIE Astronomical Telescopes + Instrumentation 2014, conference 915