| 1. |
- Biedron, Sandra G., et al.
(författare)
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Measurements of nonlinear harmonic generation at the Advanced Photon Source's SASE FEL
- 2002
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Ingår i: Nuclear Instruments & Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment. - 0167-5087. ; 483:1-2, s. 94-100
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Tidskriftsartikel (refereegranskat)abstract
- SASE saturation was recently achieved at the Advanced Photon Source's SASE FFL in the low-energy undulator test line at 530 nm and 385 urn. The electron beam microbunching becomes more and more prominent until saturation is achieved. This bunching causes nonlinear harmonic emission that extends the usefulness of a SASE system in achieving shorter FEL wavelengths for the same electron beam energy. We have investigated the intensity of the fundamental and second harmonic undulator radiation as a function of distance along the undulator line and present the experimental results and compare them to numerical simulations. In addition, we have measured the single-shot second harmonic spectra as well as the simultaneous fundamental and second harmonic spectra and present the experimental results. (C) 2002 Elsevier Science B.V. All riudits reserved.
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| 2. |
- Lewellen, JW, et al.
(författare)
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Present status and recent results from the APS SASE FEL
- 2002
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Ingår i: Nuclear Instruments & Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment. - 0167-5087. ; 483:1-2, s. 40-45
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Tidskriftsartikel (refereegranskat)abstract
- The Low-Energy Undulator Test Line (LEUTL) at the Advanced Photon Source, Argonne National Laboratory, is intended to demonstrate the basic operation of a SASE-based free-electron laser. Goals include comparison of experimental results With theoretical predictions and scaling laws, identification of problems relevant to fourth-generation light source construction and operation and the means of addressing them, the development of operational and diagnostic techniques to optimize SASE FEL performance and increase repeatability from run to run. and performance of initial pioneering experiments capable of exploiting the unique properties of the laser. The basic layout and operational philosophy of the LEUTL experiment is presented. A summary of past results, including saturation, is reviewed, and a description of recent results is presented. We conclude with future plans, which include pressing to shorter wavelengths and incorporating user experiments into the LEUTL experimental program.
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| 3. |
- Milton, AH, et al.
(författare)
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Chronic arsenic poisoning and respiratory effects in Bangladesh
- 2001
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Ingår i: Journal of Occupational Health. - 1341-9145 .- 1348-9585. ; 43:3, s. 136-140
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Tidskriftsartikel (refereegranskat)abstract
- A large population in Bangladesh have been exposed to naturally occurring inorganic arsenic through their drinking water. A prevalence comparison study of respiratory disorders among subjects with and without arsenic exposure through drinking water was conducted in Bangladesh. Characteristic skin lesions, keratoses and pigmentation alteration, and the water arsenic level confirmed the arsenic exposure. Three villages were selected from health awareness campaign programs. Participants in these courtyard meetings who had suspected skin lesions, i.e., keratosis, hyperpigmentation and hypopigmentation, were examined by a well-trained medical officer to confirm the diagnosis. Unexposed subjects were randomly selected from another village, where tubewells were not contaminated with arsenic. We interviewed and examined 218 individuals irrespective of age and sex from these villages. The arsenic level in their drinking water was measured and the mean arsenic level was 614 ╡g/l (ranging from 136 ╡g/l to 1,000 ╡g/l). Information regarding respiratory system signs and symptoms was also collected. There were few smokers, and analyses were therefore confined to nonsmokers. The overall crude prevalence (or risk) among the exposed subjects for chronic cough, and chronic bronchitis, was three times the prevalence in the control population. Age was a slightly negative confounding factor. The crude prevalence ratios were noticeably increased for female participants compared to male participants. A possible explanation for this noticeably increased occurrence of respiratory signs and symptoms in women is related to the presence of weakness. These results add to the evidence that longterm ingestion of arsenic can cause respiratory problems especially among females.
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