The electrical and optical properties of chalcedony (SiO2) and striped chalcedony are determined by the impedance and optical absorption spectroscopy techniques. The capacitance, impedance, ...dissipation factor and the complex dielectric constants are measured by the parallel plate technique in the voltage frequency range 100 to 10 MHz. The dissipation factor is measured as 1.2 and 0.7 for chalcedony and striped chalcedony respectively around 10 kHz. It is found that the striped chalcedony has a major complex broad band with two absorption bands that are centered at 225 and 275 nm. The chalcedony however, has a minor absorption band which is centered at 210 nm.
•The dielectric constants of chalcedony and striped chalcedony are measured first time in literature.•It has been observed that the optical absorption spectrum of chalcedony is different from striped chalcedony.•The dielectric constant is dependent of frequency for these minerals.
A search for the doubly charmed baryon Xi_cc^+ in the decay mode Xi_cc^+ -> Lambda_c^+ K^- pi^+ is performed with a data sample, corresponding to an integrated luminosity of 0.65/fb, of pp collisions ...recorded at a centre-of-mass energy of 7 TeV. No significant signal is found in the mass range 3300-3800 MeV/c^2. Upper limits at the 95% confidence level on the ratio of the Xi_cc^+ production cross-section times branching fraction to that of the Lambda_c^+, R, are given as a function of the Xi_cc^+ mass and lifetime. The largest upper limits range from R < 1.4 x 10^-2 for a lifetime of 100 fs to R < 3.4 x 10^-4 for a lifetime of 400 fs.
The polarisation of prompt
ψ
(
2
S
)
mesons is measured by performing an angular analysis of
ψ
(
2
S
)
→
μ
+
μ
-
decays using proton-proton collision data, corresponding to an integrated luminosity ...of 1.0
fb
-
1
, collected by the LHCb detector at a centre-of-mass energy of 7 TeV. The polarisation is measured in bins of transverse momentum
p
T
and rapidity
y
in the kinematic region
3.5
<
p
T
<
15
GeV
/
c
and
2.0
<
y
<
4.5
, and is compared to theoretical models. No significant polarisation is observed.
Optical properties of diluted magnetic semiconductor Ga sub(0.999)Mn sub(0.001)As/AlAs quantum well structures grown on (1 0 0 ), (1 1 0), (3 1 1)B and (4 1 1)B by molecular beam epitaxy are ...reported. Temperature-dependent spectral photoluminescence (PL) measurement was performed at temperatures between 15 and 300 K. The PL measurements showed that band gap of the alloy decreases with increasing lattice temperature regardless the growth orientations. S-shaped temperature dependence has been observed in the samples grown on (1 0 0), (3 1 1)B, (4 1 1)B orientations. PL emission energy is fitted with Varshni and Bose-Einstein Approximation to determine Debye temperature ( beta ), ( Theta sub(E)) and thermal expansion coefficient ( alpha ), the exciton-phonon coupling strength (a sub(B)).
Optical properties of diluted magnetic semiconductor Ga
0.999
Mn
0.001
As/AlAs quantum well structures grown on (1 0 0 ), (1 1 0), (3 1 1)B and (4 1 1)B by molecular beam epitaxy are reported. ...Temperature-dependent spectral photoluminescence (PL) measurement was performed at temperatures between 15 and 300 K. The PL measurements showed that band gap of the alloy decreases with increasing lattice temperature regardless the growth orientations. S-shaped temperature dependence has been observed in the samples grown on (1 0 0), (3 1 1)B, (4 1 1)B orientations. PL emission energy is fitted with Varshni and Bose-Einstein Approximation to determine Debye temperature (β), (Θ
E
) and thermal expansion coefficient (α), the exciton-phonon coupling strength (a
B
).
The first measurement of the effective lifetime of the ¯ B 0 s meson in the decay ¯ B 0 s → D − s D + s is reported using a proton-proton collision data set, corresponding to an integrated luminosity ...of 3 fb − 1 , collected by the LHCb experiment. The measured value of the ¯ B 0 s → D − s D + s effective lifetime is 1.379 ± 0.026 ± 0.017 ps , where the uncertainties are statistical and systematic, respectively. This lifetime translates into a measurement of the decay width of the light ¯ B 0 s mass eigenstate of Γ L = 0.725 ± 0.014 ± 0.009 ps − 1 . The ¯ B 0 s lifetime is also measured using the flavor-specific ¯ B 0 s → D − D + s decay to be 1.52 ± 0.15 ± 0.01 ps .
A first study of CP violation in the decay modes B±→KS0K±π∓Dh± and B±→KS0K∓π±Dh±, where h labels a K or π meson and D labels a D0 or D‾0 meson, is performed. The analysis uses the LHCb data set ...collected in pp collisions, corresponding to an integrated luminosity of 3 fb−1. The analysis is sensitive to the CP-violating CKM phase γ through seven observables: one charge asymmetry in each of the four modes and three ratios of the charge-integrated yields. The results are consistent with measurements of γ using other decay modes.
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