Search results for "Q value"
showing 9 items of 39 documents
Rare weak decays and nuclear structure
2014
Abstract. Weak interactions cause the atomic nuclei to decay via beta and double beta decays. Double beta decays are extremely rare since they are weak-interaction processes of the second order. Also (single) beta decays can be extremely rare. This can be caused by either a large di ff erence between the spins of the initial and final state (the so-called “forbidden” beta decays) or an extremely small Q value (decay energy) of the decay. All these cases are discussed in this article, and particular emphasis is given to the neutrino- less double electron capture on the double beta side of decays. peerReviewed
Two-Proton Radioactivity ofKr67
2016
In an experiment with the BigRIPS separator at the RIKEN Nishina Center, we observed two-proton (2p) emission from 67Kr. At the same time, no evidence for 2p emission of 59Ge and 63Se, two other potential candidates for this exotic radioactivity, could be observed. This observation is in line with Q value predictions which pointed to 67Kr as being the best new candidate among the three for two-proton radioactivity. 67Kr is only the fourth 2p ground-state emitter to be observed with a half-life of the order of a few milliseconds. The decay energy was determined to be 1690(17) keV, the 2p emission branching ratio is 37(14)%, and the half-life of 67Kr is 7.4(30) ms.
High-Precision Q -Value Measurement Confirms the Potential of Cs135 for Absolute Antineutrino Mass Scale Determination
2020
The ground-state-to-ground-state $\ensuremath{\beta}$-decay $Q$ value of $^{135}\mathrm{Cs}(7/{2}^{+})\ensuremath{\rightarrow}^{135}\mathrm{Ba}(3/{2}^{+})$ has been directly measured for the first time. The measurement was done utilizing both the phase-imaging ion-cyclotron resonance technique and the time-of-flight ion-cyclotron resonance technique at the JYFLTRAP Penning-trap setup and yielded a mass difference of 268.66(30) keV between $^{135}\mathrm{Cs}(7/{2}^{+})$ and $^{135}\mathrm{Ba}(3/{2}^{+})$. With this very small uncertainty, this measurement is a factor of 3 more precise than the currently adopted $Q$ value in the Atomic Mass Evaluation 2016. The measurement confirms that the f…
Smallest KnownQValue of Any Nuclear Decay: The Rareβ−Decay ofIn115(9/2+)→Sn115(3/2+)
2009
The ground-state-to-ground-state Q_{beta;{-}} value of ;{115}In was determined to 497.68(17) keV using a high-precision Penning trap facility at the University of Jyvaskyla, Finland. From this, a Q_{beta;{-}} value of 0.35(17) keV was obtained for the rare beta;{-} decay to the first excited state of ;{115}Sn at 497.334(22) keV. The partial half-life was determined to 4.1(6) x 10;{20} yr using ultra low-background gamma-ray spectrometry in an underground laboratory. Theoretical modeling of this 2nd-forbidden unique beta;{-} transition was also undertaken and resulted in Q_{beta;{-}} = 57_{-12};{+19} eV using the measured half-life. The discrepancy between theory and experiment could be attr…
Hyperfine structure constants of the CaII states 4s 2 S 1/2 and 4p 2 P 1/2, 3/2 and the nuclear quadrupole moment of43Ca
1991
The hyperfine structure splittings of the 4s 2 S 1/2 → 4p 2 P 1/2, 3/2 transitions in43CaII have been measured by fast ion beam collinear laser spectroscopy. The resonant laser interaction was observed using non-optical detection based on optical ground state depopulation pumping, state selective neutralization and charge state separated particle counting. The extracted magnetic dipole hyperfine structure constants for43CaA(2 S 1/2)=−805(2) MHz,A(2 P 1/2)=−145.5(1.0) MHz andA(2 P 3/2)=−31.9(0.2) MHz are in excellent agreement with relativistic many body perturbation theory predictions available for this alkali-like ion. The combined results are used to evaluate the semi-empirical analysis m…
Single and Double Beta-DecayQValues among the TripletZr96,Nb96, andMo96
2016
The atomic mass relations among the mass triplet ^{96}Zr, ^{96}Nb, and ^{96}Mo have been determined by means of high-precision mass measurements using the JYFLTRAP mass spectrometer at the IGISOL facility of the University of Jyvaskyla. We report Q values for the ^{96}Zr single and double β decays to ^{96}Nb and ^{96}Mo, as well as the Q value for the ^{96}Nb single β decay to ^{96}Mo, which are Q_{β}(^{96}Zr)=163.96(13), Q_{ββ}(^{96}Zr)=3356.097(86), and Q_{β}(^{96}Nb)=3192.05(16) keV. Of special importance is the ^{96}Zr single β-decay Q value, which has never been determined directly. The single β decay, whose main branch is fourfold unique forbidden, is an alternative decay path to the…
Experimental studies at JYFLTRAP
2007
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.
Precision 71Ga – 71Ge mass-difference measurement
2016
The 71Ga(νe, e−) 71Ge reaction Q value has been measured with the JYFLTRAP mass spectrometer at the IGISOL facility of the University of Jyv¨askyl¨a to Q = 232.443(93) keV. This value agrees with previous measurements, though it features a much higher accuracy. The Q value is being discussed in the context of the solar neutrino capture rate in 71Ga. peerReviewed
High-precision measurement of a low Q value for allowed β−-decay of 131I related to neutrino mass determination
2022
The ground-state-to-ground-state β−-decay 131I (7/2+) → 131Xe (3/2+) Q value was determined with high precision utilizing the double Penning trap mass spectrometer JYFLTRAP at the IGISOL facility. The Q value of this β−-decay was found to be Q = 972.25(19) keV through a cyclotron frequency ratio measurement with a relative precision of 1.6 × 10−9. This was realized using the phase-imaging ion-cyclotron-resonance technique. The new Q value is more than 3 times more precise and 2.3σ higher (1.45 keV) than the value extracted from the Atomic Mass Evaluation 2020. Our measurement confirms that the β−-decay to the 9/2+ excited state at 971.22(13) keV in 131Xe is energetically allowed with a Q va…