Barkas effect for antiproton stopping in H2

We report the stopping power of molecular hydrogen for antiprotons of kinetic energy above the maximum (approximately 100 keV) with the purpose of comparing with the proton one. Our result is consistent with a positive difference in antiproton-proton stopping powers above approximately 250 keV and with a maximum difference between the stopping powers of 21%+/-3% at around 600 keV.     

Neutrino indirect detection of neutralino dark matter in the CMSSM

We study potential signals of neutralino dark matter indirect detection by neutrino telescopes in a wide range of CMSSM parameters. We also compare with direct detection potential signals taking into account in both cases present and future experiment sensitivities. Only models with neutralino annihilation into gauge bosons can satisfy cosmological constraints and current neutrino indirect detection sensitivities. For both direct and indirect detection, only next generation experiments will be able to really test this kind of models. Received: 12 April 2002 / Revised version: 16 July 2002 / Published online: 18 October 2002 RID="a" ID="a" e-mail: bertin@cppm.in2p3.fr RID="b" ID="b" e-mail: nezri@in2p3.fr RID="c" ID="c" e-mail: orloff@in2p3.fr     

New measurement of the elastic scattering cross section of μd muonic atoms off deuterons

We have measured the elastic scattering cross section for the process μd + d → μd + d in ultrapure gaseous deuterium at 14 atm and at room temperature. The results is σ_dd = (8 ± 2) × 10^?20 cm².     

Synthesis and Langmuir-film formation of new dendritic DTPA-derived gadolinium(III) complexes

A series of dendritic DTPA-derived ligands and their corresponding gadolinium(III) complexes have been prepared and their spreading behaviour at the air-water interface has been investigated. The results show that these amphiphiles have the prerequisite qualities to form stable and reversible Langmuir monolayers opening the road to novel magnetic organic films.     

Deeply virtual compton scattering off the neutron

The present experiment exploits the interference between the deeply virtual Compton scattering (DVCS) and the Bethe-Heitler processes to extract the imaginary part of DVCS amplitudes on the neutron and on the deuteron from the helicity-dependent D(e,e'gamma)X cross section measured at Q2=1.9 GeV2 and xB=0.36. We extract a linear combination of generalized parton distributions (GPDs) particularly sensitive to E_{q}, the least constrained GPD. A model dependent constraint on the contribution of the up and down quarks to the nucleon spin is deduced.     

Liquid chromatography at the critical conditions in pure eluent: an efficient tool for the characterization of functional polystyrenes

Functional polymers are usually separated by liquid chromatography at critical conditions (LC-CC) using a desorli/adsorli mixture as eluent. In this paper, we describe LC-CC using dimethylformamide (DMF) as pure eluent at 72 degrees C and its application to the analysis of functional polystyrenes. The critical adsorption point is reached by tuning the temperature so that the lack of repeatability is no longer a problem. We analysed several batches of polystyrenes, exhibiting different molecular weights and functionalities. We were able to differentiate di-, mono- and non-functional polystyrenes, bearing carboxylic acid, hydroxyl or nitroxide moieties. The behaviour of these polystyrenes expressed by the experimental results was compared with their behaviour described by the LC-CC theory through the calculation of the effective interaction parameter of each end group. The technique also makes it possible to quantify the fractions of different functional polymers in a blend.     

Cryogenic Chemistry and Quantitative Non-Thermal Desorption from Pure Methanol Ices: High-Energy Electron versus X-Ray Induced Processes

X-Ray irradiation of interstellar ice analogues has recently been proven to induce desorption of molecules, thus being a potential source for the still-unexplained presence of gaseous organics in the coldest regions of the interstellar medium, especially in protoplanetary disks. The proposed desorption mechanism involves the Auger decay of excited molecules following soft X-ray absorption, known as X-ray induced electron-stimulated desorption (XESD). Aiming to quantify electron induced desorption in XESD, we irradiated pure methanol (CH₃OH) ices at 23 K with 505 eV electrons, to simulate the Auger electrons originating from the O 1s core absorption. Desorption yields of neutral fragments and the effective methanol depletion cross-section were quantitatively determined by mass spectrometry. We derived desorption yields in molecules per incident electron for CO, CO₂, CH₃OH, CH₄/O, H₂O, H₂CO, C₂H₆ and other less abundant but more complex organic products. We obtained desorption yields remarkably similar to XESD values.     

Dynamic interactive membranes with pressure-driven tunable porosity and self-healing ability

When pressure is applied to dynamic interactive membranes consisting of micelles composed of a triblock copolymer, their morphologies can be fine-tuned. Membranes with a range of porosities are accessible which can regulate and thereby control filtration performance and also display effective autonomous healing.