| 1. |
- Lieder, R M, et al.
(författare)
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Gamma-ray tracking arrays
- 2001
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Ingår i: PROGRESS IN PARTICLE AND NUCLEAR PHYSICS, VOL 46. ; , s. 399-407
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Konferensbidrag (refereegranskat)abstract
- The next generation of 4 pi arrays for high-precision gamma -ray spectroscopy will involve "gamma -ray tracking front-end on digital signal processing techniques, which allows to extract energy, timing and spatial information on the interactions of a gamma -ray in the Ge detector by pulse shape analysis of its signals. Utilizing the information on the positions of the interaction points and the energies released at each point the tracks of the gamma -rays in a Ge shell can be reconstructed in three dimensions.
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| 2. |
- Fruke, R., et al.
(författare)
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Imaging of a laser plasma source at 13 nm wavelength approaching submicrometer resolution
- 2003
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Ingår i: Journal de Physique IV. - : EDP Sciences. - 1155-4339 .- 1764-7177. ; 104, s. 153-156
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Tidskriftsartikel (refereegranskat)abstract
- Radiation in the extreme ultraviolet (EUV) spectral range is of interest for lithography and microscopy. Laser produced plasmas are sources for this kind of radiation. For successful usage it is necessary to study the source properties like size, stability and emitted spectra. For the spatial characterization of such a source a beamline was built up. The source was imaged at 13, 15 and 17 nm wavelength and at different laser energies with a resolution of better than 2 mum. As target material ethanol was used which was excited by a frequency-doubled Nd:YAG laser (lambda=532 nm; 3 ns, 30 Hz). The source was mapped with a zone plate (KZP5: d=2500 mum, Deltar(n)=0,523 mum). With a magnification of 61 the images were taken with a thinned back-illuminated CCD. Additionally a periodic structure was mapped with micrometer resolution, too.
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| 3. |
- Ristow, M, et al.
(författare)
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Frataxin deficiency in pancreatic islets causes diabetes due to loss of beta cell mass
- 2003
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Ingår i: Journal of Clinical Investigation. - 0021-9738. ; 112:4, s. 527-534
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Tidskriftsartikel (refereegranskat)abstract
- Diabetes is caused by an absolute (type 1) or relative (type 2) deficiency of insulin-producing beta cells. We have disrupted expression of the mitochondrial protein frataxin selectively in pancreatic beta cells. Mice were born healthy but subsequently developed impaired glucose tolerance progressing to overt diabetes mellitus. These observations were explained by impairment of insulin secretion due to a loss of beta cell mass in knockout animals. This phenotype was preceded by elevated levels of reactive oxygen species in knockout islets, an increased frequency of apoptosis, and a decreased number of proliferating beta cells. Hence, disruption of the frataxin gene in pancreatic beta cells causes diabetes following cellular growth arrest and apoptosis, paralleled by an increase in reactive oxygen species in islets. These observations might provide insight into the deterioration of beta cell function observed in different subtypes of diabetes in humans.
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| 4. |
- Vogt, Ulrich, et al.
(författare)
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Design and application of a zone plate monochromator for laboratory soft x-ray sources
- 2001
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Ingår i: Review of Scientific Instruments. - : AIP Publishing. - 0034-6748 .- 1089-7623. ; 72:1, s. 53-57
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Tidskriftsartikel (refereegranskat)abstract
- In this article we describe the test of a zone plate monochromator for a laboratory soft x-ray source which is a laser produced plasma on a liquid jet target. The monochromator consists of a zone plate and a pinhole. Due to the special zone plate used (condensor zone plate KZP7) the monochromator is particularly suitable for laboratory sources since it collects a relatively large solid angle in the present setup. Depending upon the diameter of the pinhole a monochromaticity of up to lambda/Delta lambda =600 can be achieved. The usefulness of the linear monochromator was proven on the basis of a filter transmission measurement. The monochromator can be used for several applications. In particular it is suitable for time-resolved x-ray absorption spectroscopy and pump and probe experiments. The use for such investigations is discussed.
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| 5. |
- Vogt, Ulrich, et al.
(författare)
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Influence of laser intensity and pulse duration on the extreme ultraviolet yield from a water jet target laser plasma
- 2001
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 79:15, s. 2336-2338
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Tidskriftsartikel (refereegranskat)abstract
- Extreme ultraviolet (EUV) emission in the 11-15 nm wavelength range from a thin liquid water jet target under illumination with a high repetition rate, high average power laser (Nd-YLF) has been studied. To find the optimum conversion efficiency of laser light into EUV radiation, different laser parameters were applied. The laser intensity was varied between 10(11) and 10(15) W/cm(2), and pulse duration in the range from 30 ps to 3 ns. A maximum conversion efficiency of 0.12% in 2.2% bandwidth and 4 pi steradian at 13 nm was achieved at a repetion rate of 250 kHz, and a strong dependence of the conversion efficiency on both laser intensity and pulse duration was found.
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