High strain rate properties of a polymer-bonded sugar: their dependence on applied and internal constraints

This paper describes research performed on a polymer-bonded sugar (PBS) consisting of 66% caster sugar in a hydroxyl-terminated polybutadiene (HTPB) binder The mechanical response of the PBS and pure HTPB to applied loading at a strain rate of approximately 2000 s-1 at temperatures from -80 to +22°C is presented. The materials were also characterized using dynamic mechanical analysis, X-ray tomography and quasi-static loading. These measurements are required for the development of intermediate strain rate constitutive models of polymer-bonded explosives, for which PBSs are a commonly used mechanical simulant. The current constitutive modelling suffers from a lack of experimental data on wellcharacterized composites and binders, especially at intermediate strain rates. This is particularly important for understanding the effects of mixing two materials. Applications of such modelling include explosive safety and fundamental understanding of the various deformation mechanisms. In this paper, the dependences of strength and deformation mechanism on temperature, and, in particular, the glass transition temperature of the binder, are shown. Physical damage plays an important role; X-ray tomography scans support debonding as the primary form of damage during roomtemperature deformation. These results are in agreement with previous investigations and are discussed in this context

Quarkonium production from d+Au to Au+Au collisions

M. Rosati on behalf of the PHENIX Collaboration EIThe PHENIX experiment measured J/$\psi$ production in pp, d+Au and Au+Au reactions at \sqrt{^sNN}$= 200 GeV over a wide range of rapidity and transverse momentum. The nuclear modification factor obtained by comparing the d+Au and pp cross sections as a function of rapidity, is consistent with shadowing of the gluon distribution functions. J/$\psi$ production in Au+Au collisions was compared to the production in pp collisions and it was found to be inconsistent with models that predict strong enhancement relative to binary collision scaling

Low mass dilepton production at RHIC energies

EIRecent results on low mass dilepton measurements from the PHENIX experiment are reported. Invariant mass spectra of $\phi-> e+e-$ are measured for the first time in Au-Au collisions at $\sqrt{^{S}NN} = 200 GeV$ in Run2. In d-Au collisions, the yields and MT slopes of both $\phi ->e+e-$ and $\phi-> K+K-$ are measured. Both results are consistent with each other within errors. In the future, a Hadron Blind Detector will be installed in PHENIX which will enhance our capabilities of rejecting external photon conversions and Dalitz pairs, that will result in a significant reduction of the large combinatorial background

Heavy flavor production in PHENIX

O. Drapier on behalf of the PHENIX Collaboration, EIThe PHENIX experiment at RHIC measured single electron spectra in p + p, d + Au and Au + Au collisions at $\sqrt{s_{NN}} = 200$ GeV, and in Au + Au collisions at $\sqrt{s_{NN}} = 62.4$ GeV. In these spectra, electrons from semi-leptonic decays of charmed particles are the dominant contribution after subtraction of all 'photonic' sources (photon conversions, Dalitz decays, decays of light vector mesons). The p + p open charm production cross-section is found to be in good agreement with pQCD NLO calculations. The shape of the distributions obtained for p + p interactions is compared with those observed for nucleus-nucleus collisions. From p + p to d + Au and Au + Au interactions, open charm production is found to scale with the number of binary collisions $N_{\rm coll}$ . Au + Au data at $\sqrt{s_{NN}} = 62.4$ GeV is compatible with the ISR p + p results scaled by $N_{\rm coll}$ . The elliptic flow parameter v2 of heavy flavor electrons has also been measured, and is found to be non-zero in the intermediate pT range