Detection of tightly closed flaws by nondestructive testing (NDT) methods in steel and titanium

X-radiographic, liquid penetrant, ultrasonic, eddy current and magnetic particle testing techniques were optimized and applied to the evaluation of 4340 steel (180 KSI-UTS) and 6Al-4V titanium (STA) alloy specimens. Sixty steel specimens containing a total of 176 fatigue cracks and 60 titanium specimens containing a total of 135 fatigue cracks were evaluated. The cracks ranged in length from .043 cm (0.017 inch) to 1.02 cm (.400 inch) and in depth from .005 cm (.002 inch) to .239 cm (.094 inch) for steel specimens. Lengths ranged from .048 cm (0.019 inch) to 1.03 cm (.407 inch) and depths from 0.010 cm (.004 inch) to .261 cm (0.103 inch) for titanium specimens. Specimen thicknesses were nominally .152 cm (0.060 inch) and 0.635 cm (0.250 inch) and surface finishes were nominally 125 rms. Specimens were evaluated in the "as machined" surface condition, after etch surface and after proof loading in a randomized inspection sequence

The FHI FEL Upgrade Design

Since coming on-line in November 2013, the Fritz-Haber-Institut (FHI) der Max-Planck-Gesellschaft (MPG) Free-Electron Laser (FEL) has provided intense, tunable infrared radiation to FHI user groups. It has enabled experiments in diverse fields ranging from bio-molecular spectroscopy to studies of clusters and nanoparticles, nonlinear solid-state spectroscopy, and surface science, resulting in 50 peer-reviewed publications so far. A significant upgrade of the FHI FEL is now being prepared. A second short Rayleigh range undulator FEL beamline is being added that will permit lasing from 160 microns. Additionally, a 500 MHz kicker cavity will permit simultaneous two-color operation of the FEL from both FEL beamlines over an optical range of 5 to 50 microns by deflecting alternate 1 GHz pulses into each of the two undulators. We will describe the upgraded FHI FEL physics and engineering design and present the plans for two-color FEL operations in November 2020

Development of a prototype superconducting radio-frequency cavity for conduction-cooled accelerators

The higher efficiency of superconducting radio-frequency (SRF) cavities compared to normal-conducting ones enables the development of high-energy continuous-wave linear accelerators (linacs). Recent progress in the development of high-quality Nb$_3$Sn film coatings along with the availability of cryocoolers with high cooling capacity at 4 K makes it feasible to operate SRF cavities cooled by thermal conduction at relevant accelerating gradients for use in accelerators. A possible use of conduction-cooled SRF linacs is for environmental applications, requiring electron beams with energy of $1 - 10$ MeV and 1 MW of power. We have designed a 915 MHz SRF linac for such an application and developed a prototype single-cell cavity to prove the proposed design by operating it with cryocoolers at the accelerating gradient required for 1 MeV energy gain. The cavity has a $\sim 3$ $\mu$m thick Nb$_3$Sn film on the inner surface, deposited on a $\sim4$ mm thick bulk Nb substrate and a bulk $\sim7$ mm thick Cu outer shell with three Cu attachment tabs. The cavity was tested up to a peak surface magnetic field of 53 mT in liquid He at 4.3 K. A horizontal test cryostat was designed and built to test the cavity cooled with three Gifford-McMahon cryocoolers. The rf tests of the conduction-cooled cavity, performed at General Atomics, achieved a peak surface magnetic field of 50 mT and stable operation was possible with up to 18.5 W of rf heat load. The peak frequency shift due to microphonics was 23 Hz. These results represent the highest peak surface magnetic field achieved in a conduction-cooled SRF cavity to date and meet the requirements for a 1 MeV energy gain

A Mission to Explore the Pioneer Anomaly

The Pioneer 10 and 11 spacecraft yielded the most precise navigation in deep space to date. These spacecraft had exceptional acceleration sensitivity. However, analysis of their radio-metric tracking data has consistently indicated that at heliocentric distances of $\sim 20-70$ astronomical units, the orbit determinations indicated the presence of a small, anomalous, Doppler frequency drift. The drift is a blue-shift, uniformly changing with a rate of $\sim(5.99 \pm 0.01)\times 10^{-9}$ Hz/s, which can be interpreted as a constant sunward acceleration of each particular spacecraft of $a_P = (8.74 \pm 1.33)\times 10^{-10} {\rm m/s^2}$. This signal has become known as the Pioneer anomaly. The inability to explain the anomalous behavior of the Pioneers with conventional physics has contributed to growing discussion about its origin. There is now an increasing number of proposals that attempt to explain the anomaly outside conventional physics. This progress emphasizes the need for a new experiment to explore the detected signal. Furthermore, the recent extensive efforts led to the conclusion that only a dedicated experiment could ultimately determine the nature of the found signal. We discuss the Pioneer anomaly and present the next steps towards an understanding of its origin. We specifically focus on the development of a mission to explore the Pioneer Anomaly in a dedicated experiment conducted in deep space.Comment: 8 pages, 9 figures; invited talk given at the 2005 ESLAB Symposium "Trends in Space Science and Cosmic Vision 2020", 19-21 April 2005, ESTEC, Noordwijk, The Netherland

Fundamental Physics with the Laser Astrometric Test Of Relativity

The Laser Astrometric Test Of Relativity (LATOR) is a joint European-U.S. Michelson-Morley-type experiment designed to test the pure tensor metric nature of gravitation - a fundamental postulate of Einstein's theory of general relativity. By using a combination of independent time-series of highly accurate gravitational deflection of light in the immediate proximity to the Sun, along with measurements of the Shapiro time delay on interplanetary scales (to a precision respectively better than 0.1 picoradians and 1 cm), LATOR will significantly improve our knowledge of relativistic gravity. The primary mission objective is to i) measure the key post-Newtonian Eddington parameter \gamma with accuracy of a part in 10^9. (1-\gamma) is a direct measure for presence of a new interaction in gravitational theory, and, in its search, LATOR goes a factor 30,000 beyond the present best result, Cassini's 2003 test. The mission will also provide: ii) first measurement of gravity's non-linear effects on light to ~0.01% accuracy; including both the Eddington \beta parameter and also the spatial metric's 2nd order potential contribution (never measured before); iii) direct measurement of the solar quadrupole moment J2 (currently unavailable) to accuracy of a part in 200 of its expected size; iv) direct measurement of the "frame-dragging" effect on light by the Sun's gravitomagnetic field, to 1% accuracy. LATOR's primary measurement pushes to unprecedented accuracy the search for cosmologically relevant scalar-tensor theories of gravity by looking for a remnant scalar field in today's solar system. We discuss the mission design of this proposed experiment.Comment: 8 pages, 9 figures; invited talk given at the 2005 ESLAB Symposium "Trends in Space Science and Cosmic Vision 2020," 19-21 April 2005, ESTEC, Noodrwijk, The Netherland

Additional evidence for fusion-fission in S32+24Mg reactions: Division of excitation energy and spin in the fission fragments

We have measured rays in coincidence with C12 fragments from the fission of Ni56 produced with the S32+24Mg reaction at Elab=140 MeV. These data provide insight into the fission process in this light system by giving information about the energy and spin sharing between the C12 and Ti44 fragments, and the spin alignment of the lighter, C12 fragment. The spin transfer and the nuclear temperature at scission deduced from this measurement can be related to the compound-nucleus spin and potential energy at scission. The results indicate a statistical decay process consistent with the predictions of the transition-state model employing newer estimates of the spin- and mass-asymmetry-dependent saddle-point energies and corresponding shapes. No evidence is found for the spin alignment of the C12 fragments, contrary to what might be expected for a deep-inelastic scattering origin of the fully energy damped yields

Commissioning Status of the Fritz Haber Institute THz FEL

The THz Free-Electron Laser (FEL) at the Fritz Haber Institute (FHI) of the Max Planck Society in Berlin is designed to deliver radiation from 3 to 300 microns using a single-plane-focusing mid-IR undulator and a two-plane-focusing far-IR undulator that acts as a waveguide for the optical mode. A key aspect of the accelerator performance is the low longitudinal emittance, < 50 keV-psec, that is specified to be delivered at 200 pC bunch charge and 50 MeV from a gridded thermionic electron source. We utilize twin accelerating structures separated by a chicane to deliver the required performance over the < 20 - 50 MeV energy range. The first structure operates at near fixed field while the second structure controls the output energy, which, under some conditions, requires running in a decelerating mode. "First Light" is targeted for the centennial of the sponsor in October 2011 and we will describe progress in the commissioning of this device to achieve this goal. Specifically, the measured performance of the accelerated electron beam will be compared to design simulations and the observed matching of the beam to the mid-IR wiggler will be described

Structured Operational Semantics for Graph Rewriting

Process calculi and graph transformation systems provide models of reactive systems with labelled transition semantics. While the semantics for process calculi is compositional, this is not the case for graph transformation systems, in general. Hence, the goal of this article is to obtain a compositional semantics for graph transformation system in analogy to the structural operational semantics (SOS) for Milner's Calculus of Communicating Systems (CCS). The paper introduces an SOS style axiomatization of the standard labelled transition semantics for graph transformation systems. The first result is its equivalence with the so-called Borrowed Context technique. Unfortunately, the axiomatization is not compositional in the expected manner as no rule captures "internal" communication of sub-systems. The main result states that such a rule is derivable if the given graph transformation system enjoys a certain property, which we call "complementarity of actions". Archetypal examples of such systems are interaction nets. We also discuss problems that arise if "complementarity of actions" is violated.Comment: In Proceedings ICE 2011, arXiv:1108.014

Design and Fabrication of the RHIC Electron-Cooling Experiment High Beta Cavity and Cryomodule

The summary of this report is: (1) A high-current SRF cavity for an Energy Recovery Linac (ERL) has been designed by BNL and AES and fabricated by AES; (2) The cavity was cleaned and tested by JLAB with BNL personnel support; (3) Cavity performance exceeded goal of 20 MV/m at Q{sub 0} &gt; 1 x 10{sup 10} and far exceeded requirement of 15 MV/m at Q{sub 0} &gt; 1 x 10{sup 10}; (4) Hermetic String assembled at JLAB with BNL personnel support and shipped to BNL; and (5) BNL has recently completed Cryomodule assembly and unit is ready for installation in the ERL vault

Pioneer Anomaly and the Kuiper Belt mass distribution

Pioneer 10 and 11 were the first probes sent to study the outer planets of the Solar System and Pioneer 10 was the first spacecraft to leave the Solar System. Besides their already epic journeys, Pioneer 10 and 11 spacecraft were subjected to an unaccounted effect interpreted as a constant acceleration toward the Sun, the so-called Pioneer anomaly. One of the possibilities put forward for explaining the Pioneer anomaly is the gravitational acceleration of the Kuiper Belt. In this work we examine this hypothesis for various models for the Kuiper Belt mass distribution. We find that the gravitational effect due to the Kuiper Belt cannot account for the Pioneer anomaly. Furthermore, we have also studied the hypothesis that drag forces can explain the the Pioneer anomaly; however we conclude that the density required for producing the Pioneer anomaly is many orders of magnitude greater than those of interplanetary and interstellar dust. Our conclusions suggest that only through a mission, the Pioneer anomaly can be confirmed and further investigated. If a mission with these aims is ever sent to space, it turns out, on account of our results, that it will be also a quite interesting probe to study the mass distribution of the Kuiper Belt.Comment: Plain latex; 17 pages, 12 figures. Version to appear in Classical and Quantum Gravity (2006