2,405 research outputs found
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Status of the PEP-II asymmetric B-factory
No full textThe PEP-II project is an e{sup +}e{sup {minus}} storage ring complex with unequal energy beams to study CP violation in the B meson system. High luminosity requires a large number of bunches and a low value of beta at the collision point. The high beam current requires advances in vacuum chambers, damped RF cavities, and feedback systems. Machine elements inside the detector are required to achieve low beta values and magnetic separation
First measurement of the t odd correlation between the Z0 spin and the three jet plane orientation in polarized Z0 decays to three jets
No full textWe present the first measurement of the correlation between the Z(0) spin and the event-plane orientation in polarized Z(0) decays into three jets in the SLAC Linear Collider Large Detector experiment at SLAC utilizing a longitudinally polarized electron beam. The CP-even and T-odd triple product (S) over right arrow(Z) .((k) over right arrow(1) x (k) over right arrow(2)), formed from the two fastest jet momenta (k) over right arrow(1) and (k) over right arrow(2) and the Z(0) polarization vector (S) over right arrow(Z), is sensitive to physics beyond the standard model. We measure the expectation value of this quantity to be consistent with zero and set 95% C.L. limits of -0.022 < beta < 0.039 on the correlation
High-Resolution Label Free Imaging of Endogenous Chromophore via Non-Linear Photoacoustic Microscopy
No full textMolecular specific subcellular imaging of biological tissues is vital for understanding the mechanisms of various pathologies. Current technologies for subcellular absorption contrast imaging, such as fluorescence confocal microscopy, require exogenous contrast agents to gain access to relevant biomolecules. All non-fluorescing biomolecules must therefore be tagged by a fluorescent marker to be visible in fluorescence confocal images. While these markers are effective, they can change the local environments, and any exogenous contrast agent must first achieve FDA approval for wide-spread use in humans.
Photoacoustic microscopy (PAM) is a hybrid imaging modality combining optical absorption imaging with ultrasonic detection capable of endogenous absorption contrast. Unfortunately, traditional photoacoustic microscopy suffers from poor axial resolution, precluding it from three-dimensional subcellular imaging. High axial resolution may be lent to PAM through the addition of a pump-probe spectroscopy technique known as transient absorption. This high resolution PAM technique, known as transient absorption ultrasonic microscopy (TAUM) enables three-dimensional subcellular imaging of endogenous biomolecules.
The pump-probe spectroscopy properties inherent to TAUM provide optically resolved point spread functions, access to ground state recovery time, and access to transient absorption spectrum measurements. This manuscript describes the author���s efforts to improve the processing capabilities of both PAM and TAUM.
In this manuscript various TAUM systems are designed and characterized in detail. A second generation TAUM system improves the processing speed of TAUM to enable processing in parallel with data acquisition. Following the improvements to processing, a novel optical schematic of TAUM is developed, greatly simplifying the design requirements of TAUM images. This system is validated by collecting volumetric images of erythrocytes in blood smears. This work enables any PAM system to be converted to a TAUM system through the addition of an optical modulator. The culmination of this work is a multispectral TAUM system hybridized with a confocal microscope to enable high resolution imaging with both scattering and absorption contrast of biological tissues. The capabilities of this PAM and TAUM are demonstrated by obtaining high resolution images of the endogenous chromophores: hemoglobin, melanin, and cytochrome C
Search for CP violation using T-odd correlations in D(+) -> K(+)K(S)(0) pi(+)pi(-) and D(s)(+) -> K(+)K(S)(0) pi(+)pi(-) decays
No full textWe search for CP violation in a sample of 20 000 Cabibbo-suppressed decays, D+→K+KS0π+π-, and 30 000 Cabibbo-favored decays, Ds+→K+KS0π+π-. We use 520 fb-1 of data recorded by the BABAR detector at the PEP-II asymmetric-energy e+e- collider operating at center of mass energies near 10.6 GeV. We search for CP violation in the difference between the T-odd asymmetries obtained using triple product correlations of the D+ (Ds+) and D- (Ds-) decays, respectively. The T violation parameter values obtained are AT(D+)=(-12.0±10.0stat±4.6syst)×10-3 and AT(Ds+)=(-13.6±7.7stat±3.4syst)×10-3, which are consistent with the standard model expectations
Measurement of D-s(+) and D-s(*+) production in B meson decays and from continuum e(+)e(-) annihilation at root s=10.6 GeV
No full textNew measurements of D-s(+) and D-s(*+) meson production rates from B decays and from q(q) over bar continuum events near the Y(4S) resonance are presented. Using 20.8 fb(-1) of data on the Y(4S) resonance and 2.6 fb(-1) off-resonance, we find the inclusive branching fractions B(B-->Ds+X) = (10.93+/-0.19+/-0.58+/-2.73)% and B(B-->Ds*+X) = (7.9+/-0.8+/-0.7+/-2.0)%, where the first error is statistical, the second is systematic, and the third is due to the D-s(+)-->phipi(+) branching fraction uncertainty. The production cross sections sigma(e(+)e(-)-->Ds+X)xB(D-s(+)-->phipi(+)) = 7.55+/-0.20+/-0.34 pb and sigma(e(+)e(-)-->Ds*+/-X)xB(D-s(+)-->phipi(+)) = 5.8+/-0.7+/-0.5 pb are measured at center-of-mass energies about 40 MeV below the Y(4S) mass. The branching fractions SigmaB(B-->D-s((*)+)(D) over bar ((*))) = (5.07+/-0.14+/-0.30+/-1.27)% and SigmaB(B-->D-s(*+)(D) over bar ((*))) = (4.1+/-0.2+/-0.4+/-1.0)% are determined from the D-s((*)+) momentum spectra. The mass difference m(D-s(+)) -m(D+) = 98.4+/-0.1+/-0.3 MeV/c(2) is also measured
Exclusive production of Ds+Ds-,D-s*D-+(s)-, and D-s*D-+(s)*(-) via e(+)e(-) annihilation with initial-state radiation
No full textWe perform a study of exclusive production of Ds+Ds-,D-s*(+),D-s(-), and D-s*D-+(s)*- final states in initial-state radiation events from e(+)e(-) annihilations at a center-of-mass energy near 10.58 GeV, to search for charmonium 1(--) states. The data sample corresponds to an integrated luminosity of 525 fb(-1) and was recorded by the BABAR experiment at the PEP-II storage ring. Ds+Ds-,D-s*(+),D-s(-) and ,D-s*(+),D-s*(-) mass spectra show evidence of the known psi resonances. Limits are extracted for the branching ratios of the decays X(4260) -> D-s(()*()+) D-s(()*()-
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Search for CP Violation using T-odd Correlations in D+ to K+K0spi+pi- and DS+ to K+K0spi+pi- Decays
No full textWe search for CP violation in a sample of 20,000 Cabibbo-suppressed decays, D{sup +} {yields} K{sup +}K{sub S}{sup 0}{pi}{sup +}{pi}{sup -}, and 30,000 Cabibbo-favored decays, D{sub s}{sup +} {yields} K{sup +}K{sub S}{sup 0}{pi}{sup +}{pi}{sup -}. We use 520 fb{sup -1} of data recorded by the BABAR detector at the PEP-II asymmetric-energy e{sup +}e{sup -} collider operating at center of mass energies near 10.6 GeV. We search for CP violation in the difference between the T-odd asymmetries obtained using triple product correlations of the D+ (D{sub s}{sup +}) and D{sup -} (D{sub s}{sup -}) decays, respectively. The T violation parameter values obtained are {Alpha}{sub T} (D{sup +}) = (-12.0 {+-} 10.0{sub stat} {+-} 4.6{sub syst}) x 10{sup -3} and {Alpha}{sub T}(D{sub s}{sup +}) = (-13.6 {+-} 7.7{sub stat} {+-} 3.4{sub syst}) x 10{sup -3}, which are consistent with the Standard Model expectations
The primary structure of three hemoglobin chains from the indigo snake (Drymarchon corais erebennus, Serpentes): First evidence for αD chains and two β chain types in snakes
No full textThe hemoglobin of the indigo snake (Drymarchon corais erebennus, Colubrinae) consists of two components, HbA and HbD, in the ratio of 1:1. They differ in both their alpha and beta chains. The amino acid sequences of both alpha chains (alpha(A) and alpha(D)) and one beta chain (betaI) were determined. The presence of an alpha(D)chain in a snake hemoglobin is described for the first time. A comparison of all snake beta chain sequences revealed the existence of two paralogous beta chain types in snakes as well, which are designated as betaI and betaII type. For the discussion of the physiological properties of Drymarchon hemoglobin, the sequences were compared with those of the human alpha and beta chains and those of the closely related water snake Liophis miliaris where functional data are available. Among the heme contacts, the substitution alpha(D)58(E7)His-->Gln is unusual but most likely without any effect. The residues responsible for the main part of the Bohr effect are the same as in mammalian hemoglobins. In each of the three globin chains only two residues at positions involved in the alpha1/beta2 interface contacts, most important for the stability and the properties of the hemoglobin molecule, are substituted with regard to human hemoglobin. On the contrary, nine, eleven, and six alpha1/beta1 contact residues are replaced in the alpha(A), alpha(D), betaI chains, respectively
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