0000000000352331
AUTHOR
R. Zahn
Radiation detected resonance ionization spectroscopy on208Tl and242fAm
An ultra-sensitive laser spectroscopic method has been developed for the hyperfine spectroscopy of short-lived isotopes far off stability produced by heavy ion induced nuclear reactions at very weak intensity (> 1/s). It is based on resonance ionization spectroscopy in a buffer gas cell with radiation detection of the ionization process (RADRIS). As a first on-line application of RADRIS optical spectroscopy at242fAm fission isomers is in progress at the low target production rate of 10/s. The resonance ionization has been performed in two steps utilizing an excimer dye laser combination with a repetition rate of 300 Hz. The first resonant step proceeds through terms which correspond to wave…
Isotope Shift Measurements for Superdeformed Fission Isomeric States
Optical isotope shift measurements have been performed for the ${}^{240,242}{\mathrm{Am}}^{f}$ fission isomers with low target production rates of $10{\mathrm{s}}^{\ensuremath{-}1}$ employing resonance ionization spectroscopy in a buffer gas cell. Isotope shift ratios ${\mathrm{IS}}^{240f,241}/{\mathrm{IS}}^{243,241}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}39.2(8)$ and ${\mathrm{IS}}^{242f,241}/{\mathrm{IS}}^{243,241}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}41.4(8)$ have been measured at the 500.02 nm transition. A difference in the nuclear mean charge radii $\ensuremath{\delta}〈{r}^{2}{〉}_{\mathrm{opt}}^{242f,241}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}5.34(2…
Resonant transition radiation in the X-ray region from a low emittance 855 MeV electron beam
The interference of transition radiation coherently produced from a periodic stack of four polyimide foils of 7.2 μm thickness and a separation of 162 μm was investigated. This stack has been brought into the low emittance (3 π nm rad) electron beam of the 855 MeV Mainz Microtron MAMI. Transition radiation was observed in the energy range from 2 to 15 keV with a LN2-cooled pin photodiode. A good energy resolution of 0.8 keV and angular resolution of 0.15 mrad was achieved simultaneously allowing for the first time to quantitatively study the interference pattern. Good agreement with theoretical calculations is found. Prospects to exploit transition radiation in the x-ray region from a low e…
First observation of a resonance ionization signal on242mAm fission isomers
The feasibility of a hyperfine spectroscopy on242mAm fission isomers has been demonstrated at the low target production rate of 10/s. The experimental method employed is based on resonance ionization spectroscopy in a buffer gas cell with detection of the ionization process by means of the fission decay of the isomers. The resonance ionization has been performed in two steps, utilizing an excimer dye laser combination with a repetition rate of 300 Hz. The first resonant step proceeds through theJ=7/2 term at 21440.35 cm−1, which has been excited with the tuncable dye laser beam of a wavelength of 466.28 nm, the second non-resonant step is achieved with the 351 nm radiation of the excimer la…
Transition radiation in the x-ray region from a low emittance 855 MeV electron beam
A quasi-monochromatic hard x-ray beam with a photon energy of 33 keV has been produced from transition radiation (TR) at the Mainz Microtron MAMI. The radiator was a stack of 30 polyimide foils of 25 μm thickness and 75 μm separation and the monochromator a highly-oriented pyrolytic graphite crystal. The intrinsic bandwidth was measured with a critical absorption technique to be 100 eV. On the basis of these experiments a photon flux of 4⋅109/mm2s over an illuminated area of 5.7×125 mm2 can be expected from an optimized beryllium radiator at a beam current of 100 μA. At the K-absorption edge of titanium at 5 keV narrow band transition radiation has been observed from a stack of four foils o…