0000000000936606
AUTHOR
S. Rahaman
Experimental studies at JYFLTRAP
JYFLTRAP is a Penning trap system at the accelerator laboratory in Jyvaskyla, Finland that enables high-precision experiments with stored, exotic species that are produced at the IGISOL facility. On one hand, these can be performed within the trap itself, like e.g. mass spectrometry. On the other hand, the trap can be used to provide the highly purified species for further experiments, e.g. for trap-assisted nuclear decay spectroscopy. This contribution focuses on these two possible applications with the presentation of some recent results on superallowed beta decays.
Electron-capture branch of Tc-100 and tests of nuclear wave functions for double-beta decays
We present a measurement of the electron-capture branch of 100Tc. Our value, B(EC)=(2.6±0.4)×10−5, implies that the 100Mo neutrino absorption cross section to the ground state of 100Tc is roughly one third larger than previously thought. Compared to previous measurements, our value of B(EC) prevents a smaller disagreement with QRPA calculations relevant to double-β decay matrix elements.
Precise half-life measurement of the Si-26 ground state
The beta-decay half-life of 26Si was measured with a relative precision of 1.4*10e3. The measurement yields a value of 2.2283(27) s which is in good agreement with previous measurements but has a precision that is better by a factor of 4. In the same experiment, we have also measured the non-analogue branching ratios and could determine the super-allowed one with a precision similar to the previously reported measurements. The experiment was done at the Accelerator Laboratory of the University of Jyvaskyla where we used the IGISOL technique with the JYFLTRAP facility to separate pure samples of 26Si.
Applications of the total absorption technique to improve reactor decay heat calculations: study of the beta decay of [sup 102,104,105]Tc
The decay heat of the fission products plays an important role in predicting the heat‐up of nuclear fuel after reactor shutdown. This form of energy release is calculated as the sum of the energy‐weighted activities of all fission products P(t) = ΣEiλiNi(t), where Ei is the decay energy of nuclide i (gamma and beta component), λi is the decay constant of nuclide i and Ni(t) is the number of nuclide i at cooling time t. Even though the reproduction of the measured decay heat has improved in recent years, there is still a long standing discrepancy at t∼1000 s cooling time for some fuels. A possible explanation for this disagreement can been found in the work of Yoshida et al. [1], who demonst…
Excited states inPd115populated in theβ−decay ofRh115
Excited states in $^{115}\mathrm{Pd}$, populated following the ${\ensuremath{\beta}}^{\ensuremath{-}}$ decay of $^{115}\mathrm{Rh}$ have been studied by means of $\ensuremath{\gamma}$ spectroscopy after the Penning-trap station at the IGISOL facility, University of Jyv\"askyl\"a. The $1$$/$$2$${}^{+}$ spin and parity assignment of the ground state of $^{115}\mathrm{Pd}$, confirmed in this work, may indicate a transition to an oblate shape in Pd isotopes at high neutron number.
Mass measurements and implications for the energy of the high-spin isomer in 94Ag.
Nuclides in the vicinity of 94Ag have been studied with the Penning trap mass spectrometer JYFLTRAP at the Ion-Guide Separator On-Line. The masses of the two-proton-decay daughter 92Rh and the beta-decay daughter 94Pd of the high-spin isomer in 94Ag have been measured, and the masses of 93Pd and 94Ag have been deduced. When combined with the data from the one-proton or two-proton-decay experiments, the results lead to contradictory mass excess values for the high-spin isomer in 94Ag, -46370(170) or -44970(100) keV, corresponding to excitation energies of 6960(400) or 8360(370) keV, respectively.
Mass Measurements of Very Neutron-Deficient Mo and Tc Isotopes and Their Impact on rp Process Nucleosynthesis
The masses of ten proton-rich nuclides, including the N=Z+1 nuclides 85-Mo and 87-Tc, were measured with the Penning trap mass spectrometer SHIPTRAP. Compared to the Atomic Mass Evaluation 2003 a systematic shift of the mass surface by up to 1.6 MeV is observed causing significant abundance changes of the ashes of astrophysical X-ray bursts. Surprisingly low alpha-separation energies for neutron-deficient Mo and Tc are found, making the formation of a ZrNb cycle in the rp process possible. Such a cycle would impose an upper temperature limit for the synthesis of elements beyond Nb in the rp process.
Double-beta decay Q values of 116Cd and 130Te
Abstract The Q values of the 116Cd and 130Te double-beta decaying nuclei were determined by using a Penning trap mass spectrometer. The new atomic mass difference between 116Cd and 116Sn of 2813.50(13) keV differs by 4.5 keV and is 30 times more precise than the previous value of 2809(4) keV. The new value for 130Te, 2526.97(23) keV is close to the Canadian Penning trap value of 2527.01 ± 0.32 keV (Scielzo et al., 2009) [1] , but differs from the Florida State University trap value of 2527.518 ± 0.013 keV (Redshaw et al., 2009) [2] by 0.55 keV (2σ). These values are sufficiently precise for ongoing neutrinoless double-beta decay searches in 116Cd and 130Te. Hence, our Q values were used to …
TAS measurements for reactor physics and nuclear structure
In this contribution we will present recent total absorption measurements of the beta decay of neutron‐rich nuclei performed at the IGISOL facility of the Univ. of Jyvaskyla. In the measurements the JYFL Penning Trap was used as a high resolution isobaric separator. The total absorption technique will be described and the impact of recent results in the fields of reactor physics (decay heat calculations) and nuclear structure will be discussed.
Electron-capture branch of 100Tc and tests of nuclear wave functions for double-beta decays
We present a measurement of the electron-capture branch of $^{100}$Tc. Our value, $B(\text{EC}) = (2.6 \pm 0.4) \times 10^{-5}$, implies that the $^{100}$Mo neutrino absorption cross section to the ground state of $^{100}$Tc is roughly one third larger than previously thought. Compared to previous measurements, our value of $B(\text{EC})$ prevents a smaller disagreement with QRPA calculations relevant to double-$\beta$ decay matrix elements.