摘要:

A third generation 2 GeV light source is under development in Pohang. The injector is a full energy linac which, when completed at the end of 1994, is expected to provide intense, low emittance radiation of photon beams with continuous wavelength down to 0.5 A.

ISSN:0094-243X    

DOI:10.1063/1.39811

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

ELETTRA is a new ultra‐high brightness VUV/soft X‐ray synchrotron facility currently under construction by Sincrotrone Trieste in Italy. A status report is printed hear. (AIP)

ISSN:0094-243X    

DOI:10.1063/1.39855

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The Advanced Light Source, a third‐generation national synchrotron‐radiation facility now under construction at the Lawrence Berkeley Laboratory, is scheduled to begin serving qualified users across a broad spectrum of research areas in the spring of 1993. Based on a low‐emittance electron storage ring optimized to operate at 1.5 GeV, the ALS will have 10 long straight sections available for insertion devices (undulators and wigglers) and 24 high‐quality bend‐magnet ports. The short pulse width (30–50 ns) will be ideal for time‐resolved measurements. Undulators will generate high‐brightness soft x‐ray and ultraviolet (XUV) radiation from below 10 eV to above 2 keV. Wigglers and bend magnets will extend the spectrum by generating high fluxes of hard x‐rays to photon energies above 10 keV. The ALS will support an extensive research program in which XUV radiation is used to study matter in all its varied gaseous, liquid, and solid forms. The high brightness will open new areas of research in the materials sciences, such as spatially resolved spectroscopy (spectromicroscopy). Biological applications will include x‐ray microscopy with element‐specific sensitivity in the water window of the spectrum where water is much more transparent than protein. The ALS will be an excellent research tool for atomic physics and chemistry because the high flux will allow measurements to be made with tenuous gas‐phase targets.

ISSN:0094-243X    

DOI:10.1063/1.39813

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The Advanced Photon Source at Argonne National Laboratory is designed as a national synchrotron radiation user facility which will provide extremely bright, highly energetic x‐rays for multidisciplinary research. When operational, the Advance Photon Source will accelerate positrons to a nominal energy of 7 GeV. The positrons will be manipulated by insertion devices to produce x‐rays 10,000 times brighter than any currently available for research. Accelerator components, insertion devices, optical elements, and optical‐element cooling schemes have been and continue to be the subjects of intensive research and development. A call for Letters of Intent from prospective users of the Advanced Photon Source has resulted in a substantial response from industrial, university, and national laboratory researchers.

ISSN:0094-243X    

DOI:10.1063/1.39814

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

First an introduction to the basic principles of heavy ion storage rings is given, which considers the conditions for storing fast moving ions in the periodic structure of a ring given by the magnetic elements. Laser cooling and electron cooling are discussed as alternative cooling schemes and cooling results from the presently operating storage rings will be shown. The use of the high‐quality electron beam in the cooler for electron‐ion collision experiments will be demonstrated with examples of electron impact excitation and ionization, radiative, dielectronic, and collisional (three‐body) recombination, and laser stimulated recombination. We also give an overview on the different heavy‐ion storage rings running already and starting‐up in different accelerator laboratories.

ISSN:0094-243X    

DOI:10.1063/1.39815

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

For the first time, amplified spontaneous emission of Al ions was observed in a recombining plasma produced by a low‐power driving laser of only 2 joules. This lasing was achieved by sharply focusing a pumping glass laser (5 ns FWHM) to a line 40 &mgr;m wide and 12 mm long onto a slab target. The spectral lines (time integrated in the 5–50 nm region were recorded on Kodak SWR plates with a flat‐field‐type grazing incidence spectrograph which axially viewed the plasma at a distance (z) of 0.8 mm from a target surface with a spatial resolution of 200 &mgr;m. The measured gain coefficients are 3.4, 4.5, 3.4 and 3.5 for the 10.57 nm 3d–5f and 15.47 nm 3d–4f transitions in Al XI and for the 12.35 nm 3d–5f and 17.78 nm 3d–4f transitions in Al X, respectively. The gain was observed in large area of 500 &mgr;m ×600 &mgr;m around z=0.8 mm. As Al XI line emissions continue during about 6 ns (FWHM), soft‐X‐ray laser resonator is expected to be effective. The electron temperatures in the plasma in the neighborhood of the target was estimated by the filter absorption method to be 400±100 eV, which is hot enough to produce Al11+ions with high density. this result can pave the way to a low‐power‐pumped X‐ray laser.

ISSN:0094-243X    

DOI:10.1063/1.39816

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

There is a great effort worldwide to develop new X‐ray microscopes both of the imaging and of the scanning type. Undulator radiation from the next generation of high brightness synchrotron radiation storage rings will be the ideal source for such microscopes. As imaging elements, Fresnel zone plates, grazing incidence mirrors and multi‐layer coated normal incidence mirrors are being developed and applied. The engineering of these elements is determined by accurate knowledge of optical constants of the materials involved and by manufacturing accuracy. The major projects are reviewed. Finally, details and first results of the Hamburg focusing mirror scanning microscope are presented. With this instrument, imaging and microprobe analysis with less than 1&mgr; resolution is possible in the energy range 20–1300 eV. Long term improvement could yield a resolution of 0.1 &mgr;m.

ISSN:0094-243X    

DOI:10.1063/1.39793

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Recent improvements in the lateral resolution of photoemission experiments open the way to their extensive application in the life sciences. We discuss some of the preliminary tests in this novel area, and a number of possible future developments.

ISSN:0094-243X    

DOI:10.1063/1.39794

出版商:AIP    

年代:1990

数据来源: AIP

ISSN:0094-243X    

DOI:10.1063/1.39795

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We report a modification of the AT&T Bell Laboratories 6m toroidal grating monochromator at the National Synchrotron Light Source at Brookhaven National Laboratory which provides greatly improved resolution at midrange without the use of a movable exit slit. This modification is based on detailed ray tracing calculation, using the precedures developed by Haber, Howells, and McKinney and Howells, modified to include the holographic correction terms to the focusing equations. To maintain the optimum resolution requires an exit slit assembly movable over a distance of ∼20 cm. However, we show that an additional fixed slit 16.8 cm closer to the grating than the standard exit slit position gives near optimum resolution in the range 70–140 eV for the 2400 line/mm grating. Resolution measurements, using the Fermi cut‐off of various metals, confirm that the full width at half maximum (FWHM) can be kept below 100 meV for photon energies from 70 to 140 eV. Further improvement (perhaps to as low as 60 meV, FWHM) can be obtained by masking the width of the grating. The modified instrument has been successfully used in a number of studies in the far‐ultraviolet and soft x‐ray regions.

ISSN:0094-243X    

DOI:10.1063/1.39796

出版商:AIP    

年代:1990

数据来源: AIP