9,164 research outputs found
Early Electroweak and Top Quark Physics with CMS
The Large Hadron Collider is an ideal place for precision measurements of the
properties of the electroweak gauge bosons W^\pm, Z^0, as well as of the top
quark. In this article, a few highlights of the prospects for performing such
measurements with the CMS detector are summarized, with an emphasis on the
first few 1/fb of data.Comment: 4 pages, to appear in the proceedings of DIS 2007, Munich, April 200
Diffractive DIS Cross Sections and Parton Distributions
Highlights are presented mainly from two recent measurements of the
diffractive Deep Inelastic Scattering cross section at HERA. In the first, the
process is studied by tagging the leading final state proton. In
the second, events of this type are selected by requiring a large rapidity gap
devoid of hadronic activity in the proton direction. The two measurements are
compared in detail and the kinematic dependences are interpreted within the
framework of a factorisable diffractive exchange. Diffractive parton
distributions are determined from a next-to-leading order QCD analysis of the
large rapidity gap data, which can be applied to the prediction of diffractive
processes, also at the TEVATRON and the LHC.Comment: to appear in the proceedings of the 33rd Intl. Conference on High
Energy Physics, ICHEP 2006 (Moscow, July 2006
Status and Commissioning of the CMS Experiment
After a brief overview of the Compact Muon Solenoid (CMS) experiment, the
status of construction and installation is described in the first part of the
note. The second part of the document is devoted to a discussion of the general
commissioning strategy of the CMS experiment, with a particular emphasis on
trigger, calibration and alignment. Aspects of b-physics, as well as examples
for early physics with CMS are also presented. CMS will be ready for data
taking in time for the first collisions in the Large Hadron Collider (LHC) at
CERN in late 2007.Comment: Talks given at the 11th Intl. Conference on B-Physics at Hadron
Machines BEAUTY 2006, Oxford (UK), September 200
Novel crystal phase in suspensions of hard ellipsoids
We present a computer simulation study on the crystalline phases of hard
ellipsoids of revolution. For aspect ratios greater than or equal to 3 the
previously suggested stretched-fcc phase [D. Frenkel and B. M. Mulder, Mol.
Phys. 55, 1171 (1985)] is replaced by a novel crystalline phase. Its unit cell
contains two ellipsoids with unequal orientations. The lattice is simple
monoclinic. The angle of inclination of the lattice, beta, is a very soft
degree of freedom, while the two right angles are stiff. For one particular
value of beta, the close-packed version of this crystal is a specimen of the
family of superdense packings recently reported [Donev et al., Phys. Rev. Lett.
92, 255506 (2004)]. These results are relevant for studies of nucleation and
glassy dynamics of colloidal suspensions of ellipsoids.Comment: 4 pages, 4 figure
Solid-solid phase transition in hard ellipsoids
We present a computer simulation study of the crystalline phases of hard
ellipsoids of revolution. A previous study [Phys. Rev. E, \textbf{75}, 020402
(2007)] showed that for aspect ratios the previously suggested
stretched-fcc phase [Mol. Phys., \textbf{55}, 1171 (1985)] is unstable with
respect to a simple monoclinic phase with two ellipsoids of different
orientations per unit cell (SM2). In order to study the stability of these
crystalline phases at different aspect ratios and as a function of density we
have calculated their free energies by thermodynamic integration. The
integration path was sampled by an expanded ensemble method in which the
weights were adjusted by the Wang-Landau algorithm.
We show that for aspect ratios the SM2 structure is more stable
than the stretched-fcc structure for all densities above solid-nematic
coexistence. Between and our calculations reveal a
solid-solid phase transition
Crystallization in Glassy Suspensions of Hard Ellipsoids
We have carried out computer simulations of overcompressed suspensions of
hard monodisperse ellipsoids and observed their crystallization dynamics. The
system was compressed very rapidly in order to reach the regime of slow,
glass-like dynamics. We find that, although particle dynamics become
sub-diffusive and the intermediate scattering function clearly develops a
shoulder, crystallization proceeds via the usual scenario: nucleation and
growth for small supersaturations, spinodal decomposition for large
supersaturations.
In particular, we compared the mobility of the particles in the regions where
crystallization set in with the mobility in the rest of the system. We did not
find any signature in the dynamics of the melt that pointed towards the
imminent crystallization events
Threshhold analysis of phase locked loops
Computer technique for predicting threshold in phased locked loops with and without frequency modulatio
QED radiative correction to spin-density matrix elements in exclusive vector meson production
QED radiative effects are considered in the case of measurement of
spin-density matrix elements of diffractive -meson electroproduction.
Large radiative correction for is found in the kinematics of
collider experiments at HERA.Comment: 7 pages, 5 figure
Response of mouse epidermal cells to single doses of heavy-particles
The survival of mouse epidermal cells to heavy-particles has been studied In Vivo by the Withers clone technique. Experiments with accelerated helium, lithium and carbon ions were performed. The survival curve for the helium ion irradiations used a modified Bragg curve method with a maximum tissue penetration of 465 microns, and indicated that the dose needed to reduce the original cell number to 1 surviving cell/square centimeters was 1525 rads with a D sub o of 95 rads. The LET at the basal cell layer was 28.6 keV per micron. Preliminary experiments with lithium and carbon used treatment doses of 1250 rads with LET's at the surface of the skin of 56 and 193 keV per micron respectively. Penetration depths in skin were 350 and 530 microns for the carbon and lithium ions whose Bragg curves were unmodified. Results indicate a maximum RBE for skin of about 2 using the skin cloning technique. An attempt has been made to relate the epidermal cell survival curve to mortality of the whole animal for helium ions
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