[Triumf-seminars] TRIUMF Colloquium today at 11:00

[TRIUMF Seminars]

Date/Time: Thu 2021-04-01 at 11:00

Location:  Remote              

Speaker:   David Mascali (INFN - Laboratori Nazionali del Sud, Catania, Italy)

Title:     PANDORA: A new experimental setup for measuring in-plasma nuclear beta-decays of astrophysical interest

Abstract: Meeting URL: https://bluejeans.com/181888335?src=join_info

Meeting ID: 181 888 335
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Theoretical predictions [1,2] and some experiments performed on Storage Rings [3] have shown that lifetimes of beta-radionuclides can change dramatically as a function of the ionization state. PANDORA (Plasmas for Astrophysics, Nuclear Decay Observation and Radiation for Archaeometry) [4] aims at measuring, for the first time, nuclear beta-decay rates in stellar-like conditions in terms of temperature (i.e. in magnetized laboratory plasmas) for those radionuclides involved in nuclear-astrophysics processes (BBN, s-processing, CosmoChronometers, Early Solar System formation). 

Compact B-minimum magnetic plasma traps, where plasmas are sustained by microwave via Electron Cyclotron Resonance and reach density n_e~1e11-1e14 cm-3, and temperatures T_e~0.1 - 30 keV, are suitable for such studies. The decay rates can be measured as a function of the charge state distribution of the in-plasma ions. According to the Technical Design Report, the setup will consist of: a superconductive magnetic trap with B_max = 3.0 T; 14 HPGe detectors for measuring the decay rates; a plasma multi-diagnostic system consisting of RF interferometers and polarimeters, optical and X-ray spectroscopy, X-ray imaging and space resolved spectroscopy for the simultaneous measurement of plasma density and temperature; the setup will also allow to measure plasma optical opacities that are relevant for the kilonovae scenarios. A first list of radioisotopes, including tens of physics cases of potential interest is now available. Possible relevant physics cases include, among the others, 204Tl, 63Ni, 60Co, 171Tm, 147Pm, 85Kr, 176Lu, the pairs 187Re-187Os and 87Sr-87Rb, which play a crucial role as cosmo-clocks. 
The first measurements will focus on 94Nb (t1/2~ 20000 y), 134Cs (t1/2 ~ 2,5 y), 176Lu (t1/2 ~ 3.76x1e10). These isotopes have been short-listed according to lifetime measurements feasibility in a plasma trap; in particular,  176Lu is still debated if it is a cosmo-thermometer or a cosmo-chronometer; 134Cs investigation is relevant for the production of the s-only isotopes 134Ba and 136Ba; and 94Nb is relevant for determining the abundance of 94Mo in single or binary systems of stars.

[1] K. Takahashi and K. Yokoi, "Nuclear beta-decays of highly ionized heavy atoms in stellar interiors", Nuclear Physics A 404, 578(1983); DOI: 10.1016/0375-9474(83)90277-4
[2] K. Takahashi and K. Yokoi, "Beta-decay rates of highly ionized heavy atoms in stellar interiors", Atomic Data and Nuclear Data Tables 36, (1987) 375; DOI: https://doi.org/10.1016/0092-640X(87)90010-6
[3] Y. A. Litvinov and F. Bosch, "Be