The Marshall Space Flight Center Development of Mirror Modules for the ART-XC Instrument aboard the Spectrum-Roentgen-Gamma Mission

The Marshall Space Flight Center (MSFC) is developing x-ray mirror modules for the ART-XC instrument on board the Spectrum-Roentgen Gamma Mission under a Reimbursable Agreement between NASA and the Russian Space Research Institute (IKI.) ART-XC will consist of seven co-aligned x-ray mirror modules with seven corresponding CdTe focal plane detectors. Currently, four of the modules are being fabricated by the Marshall Space Flight Center (MSFC.) Each MSFC module consist of 28 nested Ni/Co thin shells giving an effective area of 65 sq cm at 8 keV, response out to 30 keV, and an angular resolution of 45 arcsec or better HPD. Delivery of these modules to the IKI is scheduled for summer 2013. We present a status of the ART x-ray modules development at the MSFC

Inhibitors of chloride corrosion of reinforcement steel in concrete based on derivatives of salts of carboxylic acids and dimethylaminopropylamine

In our study, we synthesised derivatives of salts of carboxylic acids and dimethylaminopropylamine: 3-(dimethylamino)propyl-1-ammonium acetate, 3-(dimethylamino)propyl-1-ammonium hexanoate, 3-(dimethylamino)propyl-1-ammonium octanoate, and 3-(dimethylamino)propyl-1-ammonium terephthalate. The structures of the molecules of the obtained substances were confirmed using physical methods: Fourier-transform infrared spectroscopy, NMR spectroscopy, and HPLC. Electrochemical methods (voltammetry and electrochemical impedance spectroscopy) and quantum chemical modeling were used to assess the inhibitory effect of the synthesised substances with regard to 35GS reinforcement steel. Experiments were conducted in a water extract from a mortar simulating concrete pore solution in the presence of chlorides inducing pitting corrosion. 3-(dimethylamino)propyl-1-ammonium terephthalate is expected to have the highest degree of protection (up to 71%) at a concentration of 2.0 g·dm–3. The highest degree of protection for the derivatives with alkyl radicals is 41–46% in a range of concentrations from 0.5 to 2.0 g·dm-3. The results of potentiodynamic measurements and quantum chemical modeling were close. Average level of degree of protection can be explained by a high concentration of chlorides in the model solution (1.00 mol·dm–3). The effectiveness of the obtained substances is to be further studied using fine-grained concrete. This will help to assess the impact of the additives on the capillary pore structure (permeability) of concrete and the concentration of chloride

Fluorinated carbonates as new diluents for extraction and separation of f-block elements

The fluorinated carbonate BK-1 solvent was studied as a diluent in extraction systems with different extracting agents – CMPO, THDGA, CyMe4-BTBP, and CyMe4-BTPhen, which are the most promising molecules for separation of minor actinides and lanthanides. Dependence of the extraction properties of the system on the concentrations of HNO3 or extracting compound, kinetics of trivalent metal extraction and extraction of the ions by neat diluent (without the addition of extracting agent) were investigated. Based on the obtained results, BK-1 is a promising candidate diluent for f-block metal separation

π+\pi^+ photoproduction on the proton for photon energies from 0.725 to 2.875 GeV

Differential cross sections for the reaction $\gamma p \to n \pi^+$ have been measured with the CEBAF Large Acceptance Spectrometer (CLAS) and a tagged photon beam with energies from 0.725 to 2.875 GeV. Where available, the results obtained here compare well with previously published results for the reaction. Agreement with the SAID and MAID analyses is found below 1 GeV. The present set of cross sections has been incorporated into the SAID database, and exploratory fits have been made up to 2.7 GeV. Resonance couplings have been extracted and compared to previous determinations. With the addition of these cross sections to the world data set, significant changes have occurred in the high-energy behavior of the SAID cross-section predictions and amplitudes.Comment: 18 pages, 10 figure

Photodisintegration of 4^4He into p+t

The two-body photodisintegration of $^4$He into a proton and a triton has been studied using the CEBAF Large-Acceptance Spectrometer (CLAS) at Jefferson Laboratory. Real photons produced with the Hall-B bremsstrahlung-tagging system in the energy range from 0.35 to 1.55 GeV were incident on a liquid $^4$He target. This is the first measurement of the photodisintegration of $^4$He above 0.4 GeV. The differential cross sections for the $\gamma$$^4$He$\to pt$ reaction have been measured as a function of photon-beam energy and proton-scattering angle, and are compared with the latest model calculations by J.-M. Laget. At 0.6-1.2 GeV, our data are in good agreement only with the calculations that include three-body mechanisms, thus confirming their importance. These results reinforce the conclusion of our previous study of the three-body breakup of $^3$He that demonstrated the great importance of three-body mechanisms in the energy region 0.5-0.8 GeV .Comment: 13 pages submitted in one tgz file containing 2 tex file and 22 postscrip figure

First measurement of target and double spin asymmetries for polarized e- polarized p --> e p pi0 in the nucleon resonance region above the Delta(1232)

The exclusive channel polarized proton(polarized e,e prime p)pi0 was studied in the first and second nucleon resonance regions in the Q2 range from 0.187 to 0.770 GeV2 at Jefferson Lab using the CEBAF Large Acceptance Spectrometer (CLAS). Longitudinal target and beam-target asymmetries were extracted over a large range of center-of-mass angles of the pi0 and compared to the unitary isobar model MAID, the dynamic model by Sato and Lee, and the dynamic model DMT. A strong sensitivity to individual models was observed, in particular for the target asymmetry and in the higher invariant mass region. This data set, once included in the global fits of the above models, is expected to place strong constraints on the electrocoupling amplitudes A_{1/2} and S_{1/2} for the Roper resonance N(1400)P11, and the N(1535)S11 and N(1520)D13 states.Comment: 13 pages, 13 figure