Ednor M. Rowe

The first use of synchrotron radiation for vacuum ultraviolet circular dichroism measurements

Abstract Synchrotron radiation (SR) from modern electron storage rings is highly linearly polarized and more intense than conventional vacuum ultraviolet continuum sources. These unique properties make SR ideal for construction of a vacuum ultraviolet circular dichroism (CD) instrument. We report the first use of SR for CD measurements and describe the instrumental setup. These measurements were carried out in the wavelength range 1325–2050 A on (+)-3-methylcyclopentanone at the Synchrotron Radiation Center of the University of Wisconsin-Madison. The signal to noise ratio, and therefore the resolution, was the best ever obtained for CD measurements in this wavelength range. This resulted in the observation of new structure and dramatic peak height changes in the CD spectrum. In addition, these measurements showed that the extension of CD measurements to higher energies is possible through the use of synchrotron radiation.

Preliminary Design of a Dedicated Synchrotron Radiation Facility

An electron storage ring to be used solely as a synchrotron radiation source has been designed for a maximum energy of 1.5 GeV, expandable to 2 GeV, and a maximum current of 1 A, High field superconducting magnet wigglers to serve as hard radiation ports have been incorporated into the ring to make available a wide range of wavelengths for simultaneous experiments. The regular lattice consists of a series of small achromatic bends forming the arcs. The wiggler magnets are placed in low-ß in the center of insertions separating these arcs. The arrangement minimizes the electron emittances and yields high source brightness. Other machine parameters are dictated by experimental requirements and apparatus as well as by cost constraints.

Assignment of π → 3d rydberg transitions in ethylene around 9 eV using MCD and synchrotron radiation

Abstract Magnetic circular dichroism measurements on ethylene are reported over the region of the 3R00 and 4R00‴ origins around 9 eV. The results show conclusively that each origin is a composite of two electronic transitions. The 3R00 origin is assigned to the Rydberg transitions, tA1 → 1B2(3dδ) + 1B3(3dδ). 4R00‴ is assigned as 1A1 → 3R00 + ν3(u).

Synchrotron light source experiments: Bringing aladdin on line

Abstract At the beginning of 1985, Aladdin, the 1 GeV electron storage ring at the Synchrotron Radiation Center of the University of Wisconsin — Madison, could achieve, at best, 1.5 mA at 800 MeV. By the end of February, 1986, the achievable current at 800 MeV had risen to 150 mA. The scientific and technical effort that led to this two order of magnitude increase in performance is described.

Operation and Performance of the University of Wisconsin - Physical Sciences Laboratory Electron Storage Ring

A 240 MeV electron storage ring has been in operation at the Physical Sciences Laboratory of the University of Wisconsin for one year. The storage ring injector is a 50 MeV FFAG electron synchrotron. The bunched beam from the synchrotron is injected into the storage ring in a single turn. Radio-frequency capture is accomplished by using the signal from the bunched beam as the master oscillator during capture. Using this method, high capture efficiency is achieved. A useful consequence of the method of radio-frequency capture is the damping of the coherent synchrotron oscillation instability. The beam may be accelerated, or decelerated, to any energy within the capability of the ring - 10 MeV to 240 MeV. The vacuum system operates at a pressure in the mid 10-10 range allowing lifetimes of many hours for low intensity beams. During the first year of operation several interesting effects have been observed. Among these were photo etching of metal from the vacuum chamber by synchrotron radiation and enhanced beam loss due to scattering from ions trapped in the electron beam. The beam also exhibits a transverse coherent instability that violates the Courant-Sessler criteria for stability.

The Synchrotron Radiation Center of the University of Wisconsin–Madison

This article presents a brief introduction to the Synchrotron Radiation Center, a description of its present capabilities, and an overview of current improvement programs.

Research Using Synchrotron Radiation

In a period of less than ten years, the use of synchrotron radiation in the study of the optical and electronic properties of solids, liquids, and gases has developed from a laboratory curiosity into a widely exploited technique applicable to the needs of investigators working in physics, chemistry, and biology. In this report we discuss the history, present state and future development of this phenomenon in far ultraviolet and soft x-ray research.

Circular intensity differential scattering measurements in the soft x-ray region of the spectrum (~16 EV to 500 EV)

We propose the use of recently developed technique of circular intensity differential scattering (CIDS), as extended to the soft x-ray region of the spectrum (16 eV to 500 eV), to study the higher order organization of the eukaryotic chromosome. CIDS is the difference in scattering power of an object when illuminated by right circularly polarized vs. left circularly polarized electromagnetic radiation of arbitrary wavelength. CIDS has been shown to be a very sensitive measure of the helical organization of the scattering object, e.g., the eukaryotic chromosome. Preliminary results of measurements of samples of bacteriophages and octopus sperm done at SRC, Wisconsin, show the technique to be very sensitive to the dimensional parameters of the particles interrogated by circularly polarized light.

Technological applications of synchrotron radiation at the synchrotron sadiation center of the university of Wisconsin

Abstract The use of synchrotron radiation for fundamental research in a wide range of disciplines is now well established, world wide. Not so well known are the technologically oriented programs that are now in progress on Aladdin [E.M. Rowe, Nucl. Instr. and Meth. B24/25 (1987) 414], the 1 GeV electron storage ring at the Synchrotron Radiation Center of the University of Wisconsin-Madison. We describe three such programs: X-ray lithography, high T c superconductor to normal conductor junction technology, and X-ray microscopy.

Recent instrumentation developments at the university of Wisconsin synchrotron radiation center

Abstract Two new monochromators have been installed at the Wisconsin Synchrotron Radiation Center and four more are being designed and constructed for installation later this year. The new instruments installed are an uhv version of a vertically dispersing Seya-Namioka monochromator and an adjustable slit version of the “Grasshopper” grazing incidence monochromator built at the University of Wisconsin Physical Sciences Laboratory for use at the Stanford Synchrotron Radiation Project The new instruments to be installed later are a 4 normal incidence monochromator designed around a high efficiency Bausch and Lomb grating ruled for the Sky Lab Program and three grazing incidence toroidal grating monochromators designed for use with special Jobin-Yvon holographic gratings. The work on the toroidal grating monochromator is proceeding in collaboration with research groups from the IBM Watson Laboratories and the University of Pennsylvania. Operating characteristics achieved or to be expected with these instruments will be discussed.