Search results for "Algorithm"
showing 10 items of 4887 documents
Mass spectrometry and decay spectroscopy of isomers across the Z=82 shell closure
2013
Recent results from a measurement campaign studying the isomerism in neutron-deficient Tl isotopes are presented. The measurements make use of a nuclear spectroscopy setup coupled to the high-resolution Penning-trap mass spectrometer ISOLTRAP at CERN's radioactive ion-beam facility ISOLDE. The mass values of 190,194Tl are improved and a mass-spin-state assignment is carried out. An additional mass measurement of the grandparent nuclide 198At allows the deduction of the spin-state ordering in 190Tl. As a result, the excitation energies of the isomers in both Tl isotopes are determined for the first time to Eex(194Tl)=260(15) keV and E ex(190Tl)=89(12) keV. Furthermore, this allows anchoring …
CLUSTERIZATION AND THE HYPERDEFORMED STATE IN THE 36Ar NUCLEUS
2011
Cluster studies have predicted both the existence of a hyperdeformed state in 36 Ar ,1 and the favorite reaction channels 24 Mg +12 C , 20 Ne +16 O for its population.1,2 Recent experimental data seem to justify these predictions,3 and Nilsson-calculations give the same shape.4 According to structure-considerations it could also be built up in alpha-emitting reactions.
Modelling of Magnetic Resonance Spectra Using Mixtures for Binned and Truncated Data
2007
Magnetic Resonance Spectroscopy (MRS) provides the biochemical composition of a tissue under study. This information is useful for the in-vivo diagnosis of brain tumours. Prior knowledge of the relative position of the organic compound contributions in the MRS suggests the development of a probabilistic mixture model and its EM-based Maximum Likelihood Estimation for binned and truncated data. Experiments for characterizing and classifying Short Time Echo (STE) spectra from brain tumours are reported.
Application of ultra-fast timing techniques to the study of exotic and weakly produced nuclei
2005
Ultra-fast time-delayed techniques have been recently applied in a number of studies where exotic nuclei were identified using advanced selection techniques. These include large Compton-suppressed Ge arrays, in-flight separators or recoil separators. Some of the new results are discussed in this presentation. Besides the results for $^{32}$Mg and $^{96}$Pd, they include the first determination of the half-life of the $8^+$ state in $^{80}$Ge, $T_1/2$ = 2.95(6) ns, and significantly more precise results for $^{51}$Mn (3680 keV level) and $^{48}$V (421 keV level), $T_1/2$ = 1760(40) ps and $T_1/2$ $\leq$ 135 ps, respectively. Development of new scintillators will steadily improve precision an…
Search for theW-exchange decaysB0→Ds(*)−Ds(*)+
2005
We report a search for the decays B{sup 0}{yields}D{sub s}{sup -}D{sub s}{sup +}, B{sup 0}{yields}D{sub s}*{sup -}D{sub s}{sup +}, and B{sup 0}{yields}D{sub s}*{sup -}D{sub s}*{sup +} in a sample of 232x10{sup 6} {upsilon}(4S) decays to BB pairs collected with the BABAR detector at the PEP-II asymmetric-energy e{sup +}e{sup -} storage ring. We find no significant signal and set upper bounds for the branching fractions: B(B{sup 0}{yields}D{sub s}{sup -}D{sub s}{sup +})<1.0x10{sup -4}, B(B{sup 0}{yields}D{sub s}*{sup -}D{sub s}{sup +})<1.3x10{sup -4}, and B(B{sup 0}{yields}D{sub s}*{sup -}D{sub s}*{sup +})<2.4x10{sup -4} at 90% confidence level.
BACKGROUND FOR (μ-, e-) CONVERSION IN NUCLEI FROM MUON DECAY IN ORBIT
1993
A reanalysis of the problem of μ- decay in orbit is done in order to estimate backgrounds for (μ-, e-) conversion. Some approximations are done in order to obtain a very simple formula for the decay rate close to the maximum electron energy. Comparison with more sophisticated approaches leads to differences in the results which cannot be easily interpreted in terms of the approximations which has been done so far. In view of the relevance of this reaction in the planning of (μ-, e-) conversion experiments we point out at the convenience of some independent accurate evaluation.
Modulational stability brought by cubic–quartic interactions of the nearest-neighbor in FK model subjected in a parametrized on-site potential
2022
Abstract This work extends to higher-order interactions the results of Ref. Nguetcho (2021), in which we discussed only on modulational instability in one-dimensional chain made of atoms, harmonically coupled to their nearest neighbors and subjected to an external on-site potential. Here we investigate the competition between cubic-quartic nonlinearities interactions of the nearest-neighbor and substrate’s deformability, and mainly discuss its impact on the modulational instability of the system. This makes it possible to adapt the theoretical model to a real physical system such as atomic chains or DNA lattices. The governing equation, derived from the modified Frenkel-Kontorova model, is …
Brownian dynamics simulations with hard-body interactions: Spherical particles
2012
A novel approach to account for hard-body interactions in (overdamped) Brownian dynamics simulations is proposed for systems with non-vanishing force fields. The scheme exploits the analytically known transition probability for a Brownian particle on a one-dimensional half-line. The motion of a Brownian particle is decomposed into a component that is affected by hard-body interactions and into components that are unaffected. The hard-body interactions are incorporated by replacing the affected component of motion by the evolution on a half-line. It is discussed under which circumstances this approach is justified. In particular, the algorithm is developed and formulated for systems with spa…
Quantum annealing with manufactured spins.
2011
Many interesting but practically intractable problems can be reduced to that of finding the ground state of a system of interacting spins. It is believed that the ground state of some naturally occurring spin systems can be effectively attained through a process called quantum annealing. Johnson et al. use quantum annealing to find the ground state of an artificial Ising spin system comprised of an array of eight superconducting flux qubits with programmable spin–spin couplings. With an increased number of spins, the system may provide a practical physical means to implement quantum algorithms, possibly enabling more effective approaches towards solving certain classes of hard combinatorial…
Tensor Network Annealing Algorithm for Two-Dimensional Thermal States
2019
Tensor network methods have become a powerful class of tools to capture strongly correlated matter, but methods to capture the experimentally ubiquitous family of models at finite temperature beyond one spatial dimension are largely lacking. We introduce a tensor network algorithm able to simulate thermal states of two-dimensional quantum lattice systems in the thermodynamic limit. The method develops instances of projected entangled pair states and projected entangled pair operators for this purpose. It is the key feature of this algorithm to resemble the cooling down of the system from an infinite temperature state until it reaches the desired finite-temperature regime. As a benchmark we …