578 research outputs found
Relativistic coupled-cluster study of RaF as a candidate for parity and time reversal violating interaction
We have employed both Z-vector method and the expectation value approach in
the relativistic coupled-cluster framework to calculate the scalar-pseudoscalar
(S-PS) P, T -odd interaction constant (W_s) and the effective electric field
(Eeff) experienced by the unpaired electron in the ground electronic state of
RaF. Further, the magnetic hyperfine structure constants of ^{223}Ra in RaF and
^{223}Ra+ are also calculated and compared with the experimental values
wherever available to judge the extent of accuracy obtained in the employed
methods. The outcome of our study reveals that the Z-vector method is superior
than the expectation value approach in terms of accuracy obtained for the
calculation of ground state property. The Z-vector calculation shows that RaF
has a high E_eff (52.5 GV/cm) and W_s (141.2 kHz) which makes it a potential
candidate for the eEDM experiment.Comment: 8 pages, 3 figure
Relativistic equation-of-motion coupled-cluster method for the electron attachment problem
The article considers the successful implementation of relativistic
equation-of-motion coupled cluster method for the electron attachment problem
(EA-EOMCC) at the level of single- and double- excitation approximation. The
implemented relativistic EA-EOMCC method is employed to calculate ionization
potential values of alkali metal atoms (Li, Na, K, Rb, Cs, Fr) and the vertical
electron affinity values of LiX (X = H, F, Cl, Br), NaY (Y = H, F, Cl) starting
from their closed-shell configuration. Both four-component and exact
two-component calculations are done for all the opted systems. Further, we have
shown the effect of spin-orbit interaction considering the atomic systems. The
results of our atomic calculations are compared with the values from the NIST
database and the results are found to be very accurate (< 1 %).Comment: 26 Pages, 3 figures, 6 Tables. Comments are welcom
Electron-nucleus scalar-pseudoscalar interaction in PbF: Z-vector study in the relativistic coupled-cluster framework
The scalar-pseudoscalar interaction constant of PbF in its ground state
electronic configuration is calculated using the Z-vector method in the
relativistic coupled-cluster framework. The precise calculated value is very
important to set upper bound limit on P,T-odd scalar-pseudoscalar interaction
constant, k_s, from the experimentally observed P,T-odd frequency shift.
Further, the ratio of the effective electric field to the scalar-pseudoscalar
interaction constant is also calculated which is required to get an independent
upper bound limit of electric dipole moment of electron, d_e, and k_s and how
these (d_e and k_s) are interrelated is also presented here.Comment: 6 pages, 1 figure
Accelerated Tests on Si and SiC Power Transistors with Thermal, Fast and Ultra-Fast Neutrons
Neutron test campaigns on silicon (Si) and silicon carbide (SiC) power MOSFETs and IGBTs
were conducted at the TRIGA (Training, Research, Isotopes, General Atomics) Mark II (Pavia, Italy)
nuclear reactor and ChipIr-ISIS Neutron and Muon Source (Didcot, U.K.) facility. About 2000 power
transistors made by STMicroelectronics were tested in all the experiments. Tests with thermal and fast
neutrons (up to about 10 MeV) at the TRIGA Mark II reactor showed that single-event burnout (SEB)
failures only occurred at voltages close to the rated drain-source voltage. Thermal neutrons did not
induce SEB, nor degradation in the electrical parameters of the devices. SEB failures during testing at
ChipIr with ultra-fast neutrons (1-800 MeV) were evaluated in terms of failure in time (FIT) versus
derating voltage curves according to the JEP151 procedure of the Joint Electron Device Engineering
Council (JEDEC). These curves, even if scaled with die size and avalanche voltage, were strongly
linked to the technological processes of the devices, although a common trend was observed that
highlighted commonalities among the failures of different types of MOSFETs. In both experiments,
we observed only SEB failures without single-event gate rupture (SEGR) during the tests. None of
the power devices that survived the neutron tests were degraded in their electrical performances.
A study of the worst-case bias condition (gate and/or drain) during irradiation was performed
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