1,727 research outputs found
Meson Mixing and Dilepton Production in Heavy Ion Collisions
We study the possibility of mixing via N-N excitations in dense
nuclear matter. This mixing is found to induce a peak in the dilepton spectra
at an invariant mass equal to that of the . We calculate the cross section
for dilepton production through mixing and we compare its size with that of
annihilation. In-medium masses and mixing angles are also calculated.
Some preliminary results of the mixing effect on the dilepton production rates
at finite temperature are also presented.Comment: To be published in the proceedings of CIPANP 200
Squeezing lepton pairs out of broken symmetries
We discuss two possible signatures of symmetry breaking that can appear in
dilepton spectra, as measured in relativistic heavy ion collisions. The first
involves scalar-vector meson mixing and is related to the breaking of Lorentz
symmetry by a hot medium. The second is related to the breaking of Furry's
theorem by a charged quark-gluon plasma. Those signals will be accessible to
upcoming measurements to be performed at the GSI, RHIC, and the LHC.Comment: 5 pages, 4 figures, talk given at the INPC 2001 (International
Conference on Nuclear Physics), 30 July - 3 August 2001, Berkeley, C
Isospin mode splitting and mixing in asymmetric nuclear matter
We estimate exclusive density and asymmetry parameter dependent dispersion
relations of various charged states of pions in asymmetric nuclear matter. The
possibility of matter induced mixing of with is clearly exposed
with the further mass modification of meson due to mixing. Asymmetry
driven mass splitting and mixing amplitude are of the same order as the
corresponding values in vacuum. Closed form analytic results for the mass
shifts and dispersion relations with and without mixing are presented.
Furthermore, we discuss the sensitivity of our results on the scalar mean field
within the framework of Quantum Hadrodynamics.Comment: 8 pages, 4 Figure
Baryonic contributions to the dilepton spectra in relativistic heavy ion collisions
We investigate the baryonic contributions to the dilepton yield in high
energy heavy ion collisions within the context of a transport model. The
relative contribution of the baryonic and mesonic sources are examined. It is
observed that most dominant among the baryonic channels is the decay of
N*(1520) and mostly confined in the region below the rho peak. In a transport
theory implementation we find the baryonic contribution to the lepton pair
yield to be small.Comment: 11 pages, 8 figure
Modification of Surface Properties of Polymeric Materials
Polymeric materials are successfully used in virtually all industries ranging from semiconductors, and coatings, to household appliances, automotive, and biomedical implants. Polymers generally have excellent bulk physical and chemical properties. However, certain properties of polymers such as low surface energy, low wettability, and high electrical resistivity sometimes limit their applications. Changing the bulk formulation of the polymers can alter some of these properties, but in general this is not acceptable as it can affect desirable bulk properties. Surface modification techniques have been used to alter polymer surfaces without affecting the bulk properties of the material. Most polymers have very high surface and bulk resistivity, which causes static charge problems in many applications. One such application is powder coating where the accumulation of excess charge causes an adverse impact on the appearance of the powder layer. Similarly the buildup of static charge during processing and application of polymer films in packaging industries is often harmful to sensitive electronic components such as those used in the computer industry. Charge buildup may be reduced by surface modification to control the surface resistivity. In this work, atmospheric plasma treatment was used to modify the surface resistivity of polymers. The surface resistivity of polyethylene film decreased from 1.28x1O16 Q/D to 5.73x1O15 Q/U at 18% RH
Green Corrosion Inhibitors
Corrosion is an unavoidable fact in everyday life but always receive attention to control due to its technical, economical, and esthetical importance. Corrosion inhibitors are one of the most widely used and economically viable methods protecting metals and alloys against corrosion. Typical corrosion inhibitors are bio-toxic organic compounds, which have serious issue on toxicity. Considering the toxicity of the inhibitors, there is a tremendous interest in searching for an eco-friendly, and non-toxic green corrosion inhibitor. This chapter briefly discusses the importance and different methods of corrosion inhibitors with a particular emphasis given to the discussion on the different characteristic feature of the green corrosion inhibitors reported in the literature as a comparative view of organic inhibitors
Study of Velocity and Materials on Tribocharging of Polymer Powders for Powder Coating Applications
Electrostatic powder deposition is widely used in a plethora of industrial-applications ranging from the pharmaceutical and food.industries, to farm equipment and automotive applications. The disadvantages of this technique are possible back corona (pin-like formations) onset and the Faraday penetration limitation (when the powder does not penetrate in some recessed areas). A possible solution to overcome these problems is to use tribochargers to electrostatically charge the powder. Tribocharging, or contact charging while two materials are in contact, is related to the work function difference between the contacting materials and generates bipolarly charged particles. The generation of an ion-free powder cloud by tribocharging with high bipolar charge and an overall charge density of almost zero, provides a better coverage of the recessed areas. In this study, acrylic and epoxy powders were fluidized and charged by passing through stainless steel, copper, aluminum, and polycarbonate static mixers, respectively. The particle velocity was varied to determine its effect on the net charge-to-mass ratio (QIM) acquired by the powders. In general, the Q/M increases rapidly when the velocity was increased from 1.5 to 2.5 m/s, remaining almost constant for higher velocities. Charge separation experiments showed bipolar charging for all chargers
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