The main interest is the implantion of 223Ra in metallic Au. The implantation of 226Ra is optional, depending on radioprotection bounadries

Huber, Gerhard

Johnston, Karl

CERN Document Server

   Fachbereich 08 - Physik, Mathematik und Informatik   Institut für Physik  Univ.-Prof. Dr. Gerhard Huber    E-Mail: Dienstgebäude:  huberg@uni-mainz.de Staudingerweg 7   Institut für Physik • 55099 Mainz • Telefon +49 6131 25969 •  Sekretariat +49 6131 39-22279 • Internet: www.physik.uni-mainz.de                Name:  Prof. Dr. G. Huber Telefon: +49 6131 39-25969 Telefax: +49 6131 39-25179    Sekretariat:    E. Stuck-Kerth Telefon: +49 6131 39-20175    Datum:    2.10.2006      Temperature effects on alpha radioactivity of 223Ra.  J. Bonn, G. Huber, R. Neugart, N. Trautmann  Universität Mainz   Spokes person: G. Huber  Contact person: Karl Johnston   The chemical environment and the atomic charge state have well known influences on the radioactive decay. These effects may modify the decay half- life by small amounts. In some special cases of fully stripped ions dramatic changes have been reported. Stable nuclides in an atomic configuration may decay by bound state beta decay. (Bosch et al.)  Very recently (Rolfs et al.) have reported on special temperature effects of the radioactive decay induced by electronic shielding variations by conduction electrons in metals. These variations were observed as small effects induced by mild temperature changes around room temperatures. These authors could explain these effects by a “classical” electron gas model (Druwe) and they have predicted a strong increase of the decay rate by an extrapolation to low temperatures.   In the case of the alpha decay of  226Ra a change by two orders of magnitude have been mentioned for temperatures of Heliq  T=4K. According to the authors a special attention should be given to the metallic environment of the radioactive atoms.  The aim of the present letter of intent is to perform a test of the temperature variation of the alpha- decay of 223Ra with a natural half- life of T1/2 =11,43d.       INTC committee     CERN- Geneva   The samples should be implanted in pure gold foils in order to avoid oxidation at the surface. After transportation to the Institut für Kernchemie Mainz, the samples will be measured at room temperature and at “low” temperature down to T = 1,8 K. This can be achieved in a special set- up used for solid ³H sources of the Mainz neutrino mass experiment.  Instead of measuring the α- lines with surface barrier detectors the coincident γ- lines at  269; 154; 144 keV in 223Ra will be counted with a pair of high efficiency Ge- detectors, avoiding any temperature effect in the source- detector geometry. The γ- line detection is possible as well in the case of 226Ra.    On the basis of the SC-ISOLDE Yields samples of   223Ra of 3.6 x 105 Bq may be collected within 1h at 1 x 108 Atoms/s. Samples of  226Ra of 10 Bq may be produced within 2h at 1 x 108 Atoms/s.   In total 4 samples are planned to be collected in order to allow different thermal treatments before measurements at room and cryogenic temperature. The collections should be possible within one shift, even when the yields given for SC-ISOLDE will not be reached at the actual production.             

Temperature effects on alpha radioactivity of $^{223}$ Ra

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Temperature effects on alpha radioactivity of 223^{223}223Ra

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Temperature effects on alpha radioactivity of $^{223}$ Ra