119932492
Fine structure of alpha decay to rotational states of heavy nuclei
To gain a better insight into alpha-decay fine structure, we calculate the relative intensities of alpha decay to 2{sup +} and 4{sup +} rotational states in the framework of the generalized liquid drop model (GLDM) and improved Royer's formula. The calculated relative intensities of alpha decay to 2{sup +} states are in good agreement with the experimental data. For the relative intensities of alpha decay to 4{sup +} states, a good agreement with experimental data is achieved for Th and U isotopes. The formula we obtain is useful for the analysis of experimental data of alpha-decay fine structure. In addition, some predicted relative intensities which are still not measured are provided for future experiments.
99483196
Correlation between muonic levels and nuclear structure in muonic atoms
Abstract A method that deals with the nucleons and the muon unitedly is employed to investigate the muonic lead, with which the correlation between the muon and nucleus can be studied distinctly. A “kink” appears in the muonic isotope shift at a neutron magic number where the nuclear shell structure plays a key role. This behavior may have very important implications for the experimentally probing the shell structure of the nuclei far away from the β -stable line. We investigate the variations of the nuclear structure due to the interaction with the muon in the muonic atom and find that the nuclear structure remains basically unaltered. Therefore, the muon is a clean and reliable probe for studying the nuclear structure. In addition, a correction that the muon-induced slight change in the proton density distribution in turn shifts the muonic levels is investigated. This correction to muonic level is as important as the Lamb shift and high order vacuum polarization correction, but is larger than anomalous magnetic moment and electron shielding correction.
7325683
Determination of the Effective Electroweak Mixing Angle from Z-Decays
Abstract The effective electroweak mixing angle sin 2 θ w is measured from the production and decay of the Z boson in e+e− interactions. The data sample corresponds to an integrated luminosity of 18pb−1 with about 420 000 hadronic and 40 000 leptonic Z decays. The mixing angle sin 2 θ w is determined from several independent measurements: the leptonic and hadronic cross sections, the forward-backward asymmetries of charged leptons and b-quarks, and the τ-polarization. The results are found to be in good agreement with each other. The value of sin 2 θ w from a fit to the asymmetries in a model independent method is 0.2321±0.0021 and from a global fit to the data in the Standard Model framework is 0.2328±0.0013.
2203801
Q value of the superallowed decay of 46V and its influence on Vud and the unitarity of the Cabibbo-Kobayashi-Maskawa matrix.
The masses of the radioactive nuclei (46)V and its decay daughter (46)Ti have been measured with the Canadian Penning Trap on-line Penning trap mass spectrometer to a precision of 1 x 10(-8). A Q(EC) value of 7052.90(40) keV for the superallowed beta decay of (46)V is obtained from the difference of these two masses. With this precise Q value, the Ft value for this decay is determined with improved precision. An investigation of an earlier Q-value measurement for (46)V uncovers a set of 7 measurements that cannot be reconciled with modern data and affects previous evaluations of V(ud) from superallowed Fermi decays. A new evaluation, adding our new data and removing the discredited subset, yields new values for G(V) and V(ud). When combined with recent results for V(us), this yields modified constraints for the unitarity of the Cabibbo-Kobayashi-Maskawa matrix and other extensions of the standard model.
118410675
A joint Chandra and XMM-Newton view of Abell 3158: a massive off-centre cool gas clump as a robust diagnostic of a merger stage
In previous works, the nearby galaxy cluster Abell 3158 was reported to possess a relatively regular, relaxed morphology in the X-ray band. By analysing the Chandra and XMM-Newton archived data of Abell 3158, we have identified a bow-edge-shaped discontinuity in the X-ray surface brightness distribution about 120 h -1 71 kpc west of the X-ray peak. This feature is found to be associated with a massive, off-centre cool gas clump, and actually forms the west boundary of the cool clump. By calculating the thermal gas pressures in the cool clump and in the free-stream region, we determine that the cool gas clump is moving at a subsonic velocity of 700 +140 -340 km s -1 (M = 0.6 +0.1 -0.3 ) towards west on the sky plane. We exclude the possibility that this cool clump was formed by local inhomogeneous radiative cooling in the intracluster medium, because of the effectiveness of the thermal conduction on the time-scale of ∼.3 Gyr. As no evidence for central active galactic nucleus activity has been found in Abell 3158, and this cool clump bears many similarities to the off-centre cool gas clumps detected in other merging clusters in terms of their mass, size, location and thermal properties (e.g. lower temperature and higher abundance as compared with the environment), we speculate that the cool clump in Abell 3158 was caused by a merger event, and is the remnant of the original central cool-core of the main cluster or the infalling subcluster. This idea is supported not only by the study of the line-of-sight velocity distribution of the cluster member galaxies, but also by the study of the gas entropy-temperature correlation. This example shows that the appearance of such massive, off-centre cool gas clumps can be used to diagnose the dynamical state of a cluster, especially when prominent shocks and cold fronts are absent.
24223006
A proposed multipole wiggler for CAMD
New insertion devices, such as a multi-pole wiggler (MPW), are being considered for CAMD. This is a consequence of the growth of CAMD's research program over the last several years, in particular after the commissioning of a 7 T wiggler, which has produced a demand for both higher beam brightness and flux density. A proposal has been submitted to the National Science Foundation for funding for a MPW which would replace the existing 7 T wavelength shifter. The outline specification for this new device is presented and also results of tests of modified optics for the CAMD storage ring which will be needed to accommodate the MPW. The modified optics have a reduced vertical aperture requirement of 20 mm at the location of the MPW. It will also be necessary to up rate the RF system to cope with the increased radiation loss.
117803515
Two-dimensional confinement of critical U(1) gauge field in the presence of Fermi surface
The compact U(1) gauge field occurs in many fractionalized descriptions of low dimensional quantum magnetism and heavy fermion systems. In this respect a fundamental question about the gauge field is whether it is confined or not in the presence of Fermi surface. In this paper we show that the U(1) gauge field with a possible positive anomalous dimension in the presence of Fermi surface has to be in the confined state, although it is strongly coupled to abundant gapless fermionic excitations near the Fermi surface in two spatial dimensions. This means that some quantum spin liquids and/or fractionalized metallic states described in terms of this kind of gauge fields with positive anomalous dimensions are unstable to other possible symmetry-breaking states, as a result, they are not be appropriate candidates for ground states in related systems. The instability obtained shows some novel features of the quantum spin liquids and/or fractionalized metallic states in the presence of Fermi surface which have not been reported in the literature. The result could be useful for further study in the quantum spin liquids and many related slave-particle gauge theories in strongly correlated electron systems.