73 research outputs found
[Letter from D. F. Prince to John J. Herrera - April 1, 1947]
No full textLetter from D. F. Prince from the Law Offices of Vesey, Prince, & Clineburg in Washington, D. C., to John J. Herrera in Houston, Texas. Prince advises Herrera to make a thorough investigation of Charles L. Belfi to determine whether or not he was qualified to serve as General Manager of a radio station. Prince thinks Herrera should also authorize John H. Barron to proceed on the new frequency because of the conflict with Mexia
Length measurement and stabilization of the diagonals of a square area laser gyroscope
No full textLarge frame ring laser gyroscopes are top sensitivity inertial sensors able to measure absolute angular rotation rate below prad s-1 in few seconds. The GINGER project is aiming at directly measuring the Lense-Thirring effect with an 1% precision on an Earth based experiment. GINGER is based on an array of large frame ring laser gyroscopes. The mechanical design of this apparatus requires a micrometric precision in the construction and the geometry must be stabilized in order to keep constant the scale factor of the instrument. The proposed control is based on square cavities, and relies on the length stabilization of the two diagonals, which must be equal at micrometric level. GP2 is the prototype devoted to the scale factor control test. As a first step, the lengths of the diagonals of the ring cavity have been measured through an interferometric technique with a statistical accuracy of some tens of nanometers, and they have been locked to the wavelength of a reference optical standard. Continuous operation has been obtained over more than 12 h, without loss of sensitivity. GP2 is located in a laboratory with standard temperature stabilization, with residual fluctuations of the order of 1 C. Besides the demonstration of the control effectiveness, the analysis of the Sagnac frequency demonstrates that relative small and low-cost ring lasers (around one meter of side) can also achieve a sensitivity of the order of nrad s-1 in the range 0.01-10 Hz in a standard environment, which is the target sensitivity in many different applications, such as rotational seismology and next generation gravitational waves detectors
Recent Results on a Rb Pulsed Optically Pumped Clock for Space Applications
No full textWe report on the recent characterization of a Rb microwave clock based on the pulsed optical pumping (POP) principle. The clock is developed in the frame of a INRIM-Leonardo collaboration intended to implement a highly stable and compact device for space applications. The physics package developed by Leonardo S.p.A. includes space-graded components, weights less than 4 kg and occupies only a 4-liters volume. It has been characterized with custom optics and electronics developed at INRIM laboratories. By taking advantage of advanced stabilization techniques for the laser and microwave pulses, this arrangement exhibits state-of-the-art short- and mid-term stability, reaching σ y (40000s) = 6×10 −16 (drift removed) for a 200000s run
[Letter from John J. Herrera to D. F. Prince - March 31, 1947]
No full textOnionskin carbon copy of a letter sent to D. F. Prince in Washington, D. C., from John J. Herrera. Herrera advises that Felix H. Morales has returned to Texas. Herrera provides an update on the status of the station manager and the roles of Mr. Cortez, Kenneth R. Hyman, and Charles L. Belfi
Microstructural development via synergic application of Binder jJetting and Quenching and Partitioning (QP) on commercial AISI 4340
No full textThis study investigates the microstructural development of commercial low-alloyed AISI 4340 steel through the synergistic application of Binder Jetting and Quenching and Partitioning (QP) processes. The material in the as-sintered condition exhibited significant variations in microstructure and mechanical properties, primarily influenced by the processing route. Carbon content was influenced by the building technique as decarburization was observed at different intensities mainly during the heating stage of sintering, driven by carbothermic reduction. Vacuum-debinding was found to be optimal, leading to the most homogeneous microstructure, predominantly granular bainite with superior hardness and tensile strength. Different QP treatments were optimized considering the decarburization effect on the optimal as-sintered condition, stabilizing 4–8 % retained austenite in a martensitic matrix, with optimal results observed after isothermal holding at either 220 °C or 240 °C for 30 min. These conditions resulted in high UTS values of 1231 MPa and 1151 MPa, respectively, compared to 750 MPa in the as-sintered state. Despite high tensile properties, A% was limited by the presence of residual porosity. This study highlights the critical importance of controlled debinding and sintering atmospheres as well as decarburization-informed QP treatments in achieving desirable microstructural and mechanical properties in additively manufactured AISI 4340 steel components
Active control and sensitivity of the "G-Pisa" gyrolaser
No full textG-Pisa is an experiment dealing with a high-sensitivity laser gyroscope operating in a square cavity of side length of the order of 1 m. We report on the active stabilization of the gyrolaser optical frequency which is mainly driven by the environmental thermal fluctuations. Stabilized operations make it possible to perform rotation measurements without interruptions due to mode jumps. The long-term stability is dominated by backscattering effects which introduce a slow and deep frequency modulation on the Sagnac interference signal. We measured a sensitivity limit, mainly given by environmental and anthropic noise, at the level of 2.10(-9) (rad/s)/root Hz. Applications of this gyrolaser as a high-sensitive tilt-meter in the large-frame interferometers for gravitational waves detection are discussed
High sensitivity rotation measurements with a mid-size laser gyroscope
No full textAn high sensitivity laser gyroscope is presented operating in a square cavity of side length of the order of 1 m with a measured sensitivity limit at the level of 2 10-9(rad/s)/ √Hz. We report on the active stabilization of the laser optical frequency which is mainly driven by the environmental thermal fluctuations and the experimental results obtained with the active stabilization system are given. Finally the applications of this gyrolaser as an high-sensitive tilt-meter in Virgo, the large-frame interferometer for gravitational waves detection, are discussed
Experimental activity toward GINGER (gyroscopes IN general relativity)2014 International Conference Laser Optics
No full textWe report about the recent progresses toward the development of a laser gyroscope detector for a ground based measurement of the Earth's relativistic frame dragging. The main part of the presented activity involves the control of the systematic errors related to the fluctuation of the cavity geometry and the active medium parameters. A new square ring laser 1.6 m in side, named “GP2”, has been built with the aim of setting its cavity shape as close as possible to a “perfect square”. This kind of setup will be the building block for an ultra-sensitive tri-axial rotation detector aiming at fundamental Physics applications
Rotational sensitivity of the G-Pisa gyrolaser
No full textG-Pisa is an experiment investigating the possibility to operate a high
sensitivity laser gyroscope with area less than for improving the
performances of the mirrors suspensions of the gravitational wave antenna
Virgo. The experimental set-up consists in a He-Ne ring laser with a 4 mirrors
square cavity. The laser is pumped by an RF discharge where the RF oscillator
includes the laser plasma in order to reach a better stability. The contrast of
the Sagnac fringes is typically above 50% and a stable regime has been reached
with the laser operating both single mode or multimode. The effect of hydrogen
contamination on the laser was also checked. A low-frequency sensitivity, below
, in the range of has been
measured
- …
