Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userHigh-$j$ neutron excitations outside $^{136}$Xe
95
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
The $ u0h_{9/2}$ and $ u0i_{13/2}$ strength at $^{137}$Xe, a single neutron outside the $N=82$ shell closure, has been determined using the $^{136}$Xe($alpha$,$^3$He)$^{137}$Xe reaction carried out at 100 MeV. We confirm the recent observation of the second 13/2$^+$ state and reassess previous data on the 9/2$^-$ states, obtaining spectroscopic factors. These new data provide additional constraints on predictions of the same single-neutron excitations at $^{133}$Sn.
rate research
Read More
Experiments searching for neutrinoless double beta decay ($0 ubetabeta$) require precise energy calibration and extremely low backgrounds. One of the most popular isotopes for $0 ubetabeta$ experiments is $^{136}$Xe. In support of these experiments, the neutron inelastic scattering properties of this isotope have been measured at the GErmanium Array for Neutron Induced Excitations (GEANIE) at the Los Alamos Neutron Science Center. Time-of-flight techniques are utilized with high-purity germanium detectors to search for inelastic scattering $gamma$ rays for neutron energies between 0.7 and 100 MeV. Limits are set on production of yet-unobserved $gamma$ rays in the energy range critical for $0 ubetabeta$ studies, and measurements are made of multiple $gamma$-ray production cross sections. In particular, we have measured the production of the 1313 keV $gamma$ ray which comes from the transition of the first-excited to ground state of $^{136}$Xe. This neutron-induced $gamma$ line may be useful for a novel energy calibration technique, described in this paper.
The change in the configuration of valence protons between the initial and final states in the neutrinoless double-$beta$ decay of $^{130}$Te $rightarrow$ $^{130}$Xe and of $^{136}$Xe $rightarrow$ $^{136}$Ba has been determined by measuring the cross sections of the ($d$,$^3$He) reaction with 101-MeV deuterons. Together with our recent determination of the relevant neutron configurations involved in the process, a quantitative comparison with the latest shell-model and interacting-boson-model calculations reveals significant discrepancies. These are the same calculations used to determine the nuclear matrix elements governing the rate of neutrinoless double-$beta$ decay in these systems.
EXO-200 is a single phase liquid xenon detector designed to search for neutrinoless double-beta decay of $^{136}$Xe to the ground state of $^{136}$Ba. We report here on a search for the two-neutrino double-beta decay of $^{136}$Xe to the first $0^+$ excited state, $0^+_1$, of $^{136}$Ba based on a 100 kg$cdot$yr exposure of $^{136}$Xe. Using a specialized analysis employing a machine learning algorithm, we obtain a 90% CL half-life sensitivity of $1.7 times 10^{24}$ yr. We find no statistically significant evidence for the $2 ubetabeta$ decay to the excited state resulting in a lower limit of $T^{2 u}_{1/2}$ ($0^+ rightarrow 0^+_1$) $> 6.9 times 10^{23}$ yr at 90% CL. This observed limit is consistent with the estimated half-life of $2.5times10^{25}$ yr.
We report the observation of two-neutrino double-beta decay in Xe-136 with T_1/2 = 2.11 +- 0.04 (stat.) +- 0.21 (sys.) x 10^21 yr. This second order process, predicted by the Standard Model, has been observed for several nuclei but not for Xe-136. The observed decay rate provides new input to matrix element calculations and to the search for the more interesting neutrino-less double-beta decay, the most sensitive probe for the existence of Majorana particles and the measurement of the neutrino mass scale.
A quantitative description of the change in ground-state neutron occupancies between $^{136}$Xe and $^{136}$Ba, the initial and final state in the neutrinoless double-$beta$ decay of $^{136}$Xe, has been extracted from precision measurements of the cross sections of single-neutron adding and -removing reactions. Comparisons are made to recent theoretical calculations of the same properties using various nuclear-structure models. These are the same calculations used to determine the magnitude of the nuclear matrix elements for the process, which at present disagree with each other by factors of 2 or 3. The experimental neutron occupancies show some disagreement with the theoretical calculations.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
