Sub-microsecond alpha particle emitters

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Titel Sub-microsecond alpha particle emitters
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Beskrivning Above nuclear shell closures, fast α-decaying nuclei with half-lives down to tens of nanoseconds exist. Due to their short lifetimes, it has been difficult to measure their spectroscopic properties in detail as α-decays pile up in former analogue electronics experimental set-ups. For the superheavy element 115 experiment, conducted in 2012 at GSI TASCA [1, 2], fast sampling ADCs were used. This enables extraction of energies and times of pile-ups with tailor-made algorithms, and moreover, allows to correlate coincident photons, i.e. x rays or γ rays, to the individual α-decay steps. This coincidence information is crucial for any subsequent nuclear structure interpretation.

A pile-up trace analysis routine has been developed [3]. For instance from correlation plots displayed in Figure 1, a connection to the tabulated α-decay chain of Ra-219 to Rn-215 could be firmly established. In fact, multi-nucleon transfer reaction channels, which form the main background in the E115 experiment, populate the whole region of fast α-emitters “North-East” of 208Pb.

This region of sub-microsecond α-particle emitters has been thoroughly studied with the new type of data. The analysis takes off from a close examination of the α1-α2 correlation 2D-spectrum in conjunction with half lives and coincident γ rays. The results cover half-lives, decay modes and branching ratios of these short-lived nuclei which have in some cases not been studied since the 1970s. The obtained data is compared with large-scale nuclear shell-model calculations and contemporary α-decay models developed in Lund [4].

[1] D. Rudolph et al. Spectroscopy of Element 115 Decay Chains. Phys. Rev. Lett. 111, 112502. 2013.
[2] Ulrika Forsberg. Element 115. PhD thesis, Faculty of Science, Lund University, 2016.
[3] Anton Roth. Extraction of energy and time from pile-up pulses with fast sampling ADC analysis techniques. Master thesis, Faculty of Engineering, Lund University, 2016.

2017 okt 10


Ämnesklassifikation (UKÄ)

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2017 okt 10

Evenemang (Konferens)

Titel9th Workshop on the Chemistry of the Heaviest Elements
Förkortning TitelCHE9
Webbadress (URL)
PlatsFondazione Monte Verità
IgenkänningsgradInternationellt evenemang

Relaterad forskningsoutput

Såmark-Roth, A., Sarmiento, L. G., Rudolph, D., Ljungberg, J., Carlsson, B. G., Fahlander, C., Forsberg, U., Golubev, P., Ragnarsson, I., Ackermann, D., Andersson, L. L., Block, M., Brand, H., Cox, D. M., Di Nitto, A., Düllmann, C. E., Eberhardt, K., Even, J., Gates, J. M., Gerl, J. & 28 andraGregorich, K. E., Gross, C. J., Herzberg, R. D., Heßberger, F. P., Jäger, E., Khuyagbaatar, J., Kindler, B., Kojouharov, I., Kratz, J. V., Krier, J., Kurz, N., Lommel, B., Mistry, A., Mokry, C., Omtvedt, J. P., Papadakis, P., Runke, J., Rykaczewski, K., Schädel, M., Schaffner, H., Schausten, B., Thörle-Pospiech, P., Trautmann, N., Torres, T., Türler, A., Ward, A., Wiehl, N. & Yakushev, A., 2018 okt 9, I : Physical Review C. 98, 4, 11 s., 044307.

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