Park Doing

Applying ethnographic insight to engineering ethics: epistemography and accountability in the space shuttle Challenger failure and the Macondo Well blowout

This paper analyzes a recent movement in ethical studies of engineering failure that advocates for an epistemology of technical knowledge production whereby technical facts are seen as the contingent products of social practice. The paper argues that this approach raises important questions with regard to considerations of accountability in technological failures. It points out that practitioners themselves have used such an approach to deflect accountability away from themselves in the cases of the Space Shuttle Challenger failure and the Macondo Well blowout. It then argues that rather than advocate for the contingency of technical facts, ethical analysts of engineering failures should take an ‘epistemographic’ approach that questions to what effect epistemological assertions are put by practitioners themselves in the course of working on, and accounting for, engineering failures. In conclusion, the paper points to new implications for considerations of accountability in technological failures that arise from such an approach and calls for new reflection on the epistemological commitments of recent analysts of engineering failure.

CHARACTERIZATION OF A DIAMOND CRYSTAL X-RAY PHASE RETARDER

An x-ray phase retarder plate based on a diamond single crystal diffracting in the asymmetric Laue geometry has been characterized at the X25 wiggler beamline at the National Synchrotron Light Source. The forward diffracted (transmitted) beam, using the (111) Bragg planes in a 0.5 mm thick wafer with a (001) surface normal, was employed. A polarization analyzer based on a GaAs(111) crystal oriented to diffract the (222) and a different reflection simultaneously was used to determine the Stokes–Poincare polarization parameters of the beam transmitted by the diamond phase plate, at several settings of the diamond about its (111) rocking curve. At 7.1 keV, the phase plate performed as expected and it was proven possible to produce, with the plate, an almost completely left- or right-handed circularly polarized x-ray beam from a linearly polarized incident beam.

Improved internally water-cooled monochromators for a high-power wiggler beamline at CHESS

Intense synchrotron radiation from high power wiggler sources has long been a difficult high-heat-load problem to the design of properly cooled x-ray optics. Large, high power and very intense beams thermally distort crystal optics, reducing throughput and broadening rocking curves. An internally cooled silicon monochromator has been fabricated which demonstrated the capability of diffracting wiggler radiation of unprecedented power without significant degradation of the beam. Cooling water flows through rectangular cooling channels 1 mm wide, 1 mm below the diffracting surface, fed by a manifold bonded to the underside of the diffracting crystal. In an attempt to improve high power performance, a second monochromator was fabricated with a pin-fin cooling structure instead of channels. Both used a novel silver diffusion bond to ensure leak-tight UHV performance. Recent test results at wiggler station F2 show a linear behavior of the x-ray flux with increasing storage ring current up to a total power of 3 kW and a peak surface power density of 5 W/mm2. The improved monochromators have led to an increase of x-ray flux by a factor of six over previous contact-cooled designs and show that internal water-cooling can be an effective solution to high-heat-load problems at high power wiggler stations.

Bonding techniques for the fabrication of internally cooled x-ray monochromators

At CHESS, 2500 W total are absorbed by the first crystal of the double bounce monochromators located on the A2 and F2 wiggler beamlines. In order to dissipate this absorbed power and deliver the highest x-ray flux to an end station, we have explored the technique of internally cooling the silicon first crystals with water channels. This technique brings with it the need for reliable mechanical joints between the silicon diffracting surface and a glass or silicon water manifold. The joint must have structural strength to resist the internal water pressure and the cyclic heat load, be vacuum leak tight for operation in UHV, and not act as a source of residual strain in the crystal lattice of the diffracting surface. We have explored four bonding techniques which have been tested for their suitability to monochromator fabrication: direct silicon to silicon bonding, anodic glass to silicon bonding, a variety of ceramic and die attach adhesives and metallic diffusion bonding/brazing. In this paper, we characterize each method with respect to the requirements of structural integrity, residual strain and vacuum compatibility.

Epistemic Politics at Work: National Policy, an Upstate New York Synchrotron, and the Rise of Protein Crystallography

This chapter explores the linkage of local and trans-local forces in the rise of synchrotron x-ray protein crystallography. In considering how a new kind of laboratory organization, whose purpose was to spur the growth of synchrotron x-ray protein crystallography in the U.S., played a crucial role as an incubator and proving ground for experimental techniques and methods that spread throughout the burgeoning field, the chapter describes the national and regional forces involved in the birth and growth of the organization, local actions and conceptions at the laboratory, and the ‘epistemic politics’ that operationalized these factors into successful change. The chapter shows how a renegotiation of the relationship between authority, control, and knowledge production – the epistemic politics – at the lab was the crucial mechanism by which the dialectic of larger forces and local work was engaged as an ‘agent’ of growth for this emerging field.

Laboratory Studies: Historical Perspectives

Abstract The main purpose of laboratory studies has long been taken as epistemological. Seen as the coup-de-grace for constructivist philosophy of science, early practitioners of laboratory studies were seen to have disproved demarcationist theories of scientific fact production. They were supposed to have done so by revealing the messy, intertwined, sociotechnical world inside the laboratory itself. Because laboratory studies were seen in this way, they initially garnered sensational attention, but later were seen to be less important since the epistemological project was considered either to have been completed or to be a methodological non sequitur. This view of laboratory studies has obscured their actual importance and their continuing contributions to studies of science and technology. If laboratory studies are seen not as epistemological projects, but rather as investigations into technoscientific agency, their real and sustained importance to science and technology studies (STS) emerges. In this view, it can be seen that early laboratory studies set the stage for, and subsequent studies fleshed out and further challenged, debates regarding material agency, distributed organizational agency, and cultural agency in technoscience; debates that animate the field of STS to this day.

Signal Processing Collaborations from Engineer\/Art Historian Interactions

As data analytics and computation engage more fields and applications, engineers find themselves working to communicate the capabilities and benefits of complex algorithms and processing techniques to audiences that do not speak the engineer?s language of mathematics and computation. From biology to sociology to scholarship in the humanities, potential transformations and innovations rest on the ability of engineers and scientists to make the case for computational techniques and fruitfully engage with new kinds of institutions and practices. As an anthropologist of science and technology, Park Doing is interested in such interactions.

Improved optics for multiple-wavelength anomalous diffraction crystallography at CHESS

The optics at the F2 station of CHESS have been completely redesigned and rebuilt. The new design consists of a white- beam collimating mirror and a fixed-exit double-crystal monochromator, which are optimized for the growing field of multiple-wavelength anomalous diffraction (MAD) crystallography. The upstream mirror reduces the heat load onto the monochromator by two-thirds and increases the energy resolution of the x-ray beam to its source-size limit. The new single-rotation fixed-exit monochromator employs a slightly- tilted second-crystal translation that allows fast and reliable changes in the energy of the outgoing beam while maintaining its beam position. Two additional angle-segment stages, one for each crystal, are used to fine tune the second-crystal translation tilt so that the translation stage can be always positioned along the tangent of the desired loci of the second crystal for a wide energy range of 7 - 17 keV using Si (111).

Mosaic monochromator applications at CHESS

A double bounce monochromator with a roughened Si(111) first crystal and a sagitally focusing roughened Si(111) second crystal was tested at a Cornell High Energy Synchrotron Source (CHESS) bending magnet line. Flux and energy width measurements were taken and comparisons are made with measurements from a perfect Si(111) monochromator (also sagitally focused) as well as calculations for flux and energy width for a source-matched monochromator and a mosaic monochromator. For the roughened monochromator at 17 keV, the flux was greater by a factor of 7.5 while the energy spread was only increased by a factor of 2, as compared to the perfect monochromator. These measured increases are consistent with predicted values for source-matched optics. Other advantages of mosaic monochromators in addition to source- matching are discussed.

Silver bonded, internally water-cooled monochromators for CHESS wiggler beamlines

Intense synchrotron radiation from high power wiggler sources has long been a difficult high-heat-load problem to the design of properly cooled x-ray optics. Large, high power and very intense beams thermally distort crystal optics, reducing throughput and broadening rocking curves. An internally cooled silicon monochromator has been fabricated which demonstrated the capability of diffracting wiggler radiation of unprecedented power without significant degradation of the beam. Cooling water flows through rectangular cooling channels 1 mm wide, 1 mm below the diffracting surface, fed by a manifold bonded to the underside of the diffracting crystal. A novel silver diffusion bond was used to ensure leak-tight UHV performance. Recent test results at wiggler station F2 show a linear behavior of the x-ray flux with increasing storage ring current up to a total power of 3 kW and a peak surface power density of 5 W/mm2. The improved monochromator has led to an increase of x-ray flux by a factor of six over previo...