Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userElectron shakeoff following the b{eta}+ decay of 19Ne+ and 35Ar+ trapped ions
265
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
The electron shakeoff of 19F and 35Cl atoms resulting from the b{eta}+ decay of 19Ne+ and 35Ar+ ions has been investigated using a Paul trap coupled to a time of flight recoil-ion spectrometer. The charge-state distributions of the recoiling daughter nuclei were compared to theoretical calculations based on the sudden approximation and accounting for subsequent Auger processes. The excellent agreement obtained for 35Cl is not reproduced in 19F. The shortcoming is attributed to the inaccuracy of the independent particle model employed to calculate the primary shakeoff probabilities in systems with rather low atomic numbers. This calls for more elaborate calculations, including explicitly the electron-electron correlations.
rate research
Read More
The beta decay of 31Ar, produced by fragmentation of a 36Ar beam at 880 MeV/nucleon, was investigated. Identified ions of 31Ar were stopped in a gaseous time projection chamber with optical readout allowing to record decay events with emission of protons. In addition to b{eta}-delayed emission of one and two protons we have clearly observed the beta-delayed three-proton branch. The branching ratio for this channel in 31Ar is found to be 0.07(2)%.
The 15O(alpha,gamma)19Ne reaction is one of two routes for breakout from the hot CNO cycles into the rp process in accreting neutron stars. Its astrophysical rate depends critically on the decay properties of excited states in 19Ne lying just above the 15O + alpha threshold. We have measured the alpha-decay branching ratios for these states using the p(21Ne,t)19Ne reaction at 43 MeV/u. Combining our measurements with previous determinations of the radiative widths of these states, we conclude that no significant breakout from the hot CNO cycle into the rp process in novae is possible via 15O(alpha,gamma)19Ne, assuming current models accurately represent their temperature and density conditions.
We report a search for $B^{0}to eta eta $ with a data sample corresponding to an integrated luminosity of $698 ,{rm fb}^{-1}$ containing $753 times 10^{6}$ $Bbar{B}$ pairs collected at the $Upsilon(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^{+}e^{-}$ collider. The branching fraction is measured to be $mathcal{B}(B^{0} to eta eta ) = (7.6^{+2.7 +1.4}_{-2.3 -1.6}) times 10^{-7}$ at the level of 3.3 standard deviations above zero, which provides the first evidence for the decay $B^{0} to eta eta$.
The low $Q^2$ slopes of the the transition form factors provide a unique method to measure the sizes of the neutral pseudo-scalar mesons, since they do not have electromagnetic form factors. From the slope one obtains the axial transition RMS radius $ R_{PS,A} = sqrt{<r^2>}$ for each PS meson. The present status of theory and experiment for these quantities are presented. A comparison of the $ R_{PS,A}$ is presented along with the electromagnetic and scalar radii of the $pi^{pm}$ mesons and the proton. We observe the striking similarity of the values of axial transition radii of all of the pseudoscalar mesons to each other and to the charge radius of the $pi^{pm}$. In the $Q^2$ = 0 limit the transition form factor is a measure of the pseudo-scalar meson radiative width (lifetime) and is a possible fourth (unexploited) method to perform such a measurement. The $pi^{0} rightarrow gamma gamma$ decay rate is a test of QCD at the confinement scale. There is a firm QCD prediction with a theoretical uncertainty of $simeq $ 1 % which calls for an experimental test at the same level of accuracy. There are three methods that have been utilized to perform this measurement and the present status of the experimental tests are outlined. The current accuracy is significantly less than the theoretical uncertainty. The efforts to improve this are briefly summarized.
An experiment addressing electron capture (EC) decay of hydrogen-like $^{142}$Pm$^{60+}$ ions has been conducted at the experimental storage ring (ESR) at GSI. The decay appears to be purely exponential and no modulations were observed. Decay times for about 9000 individual EC decays have been measured by applying the single-ion decay spectroscopy method. Both visually and automatically analysed data can be described by a single exponential decay with decay constants of 0.0126(7) s$^{-1}$ for automatic analysis and 0.0141(7) s$^{-1}$ for manual analysis. If a modulation superimposed on the exponential decay curve is assumed, the best fit gives a modulation amplitude of merely 0.019(15), which is compatible with zero and by 4.9 standard deviations smaller than in the original observation which had an amplitude of 0.23(4).
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
