The MICROSCOPE mission was designed to test the weak equivalence principle (WEP), stating the equality between the inertial and the gravitational masses, with a precision of 10^{-15} in terms of the Eötvös ratio η. Its experimental test consisted of comparing the accelerations undergone by two collocated test masses of different compositions as they orbited the Earth, by measuring the electrostatic forces required to keep them in equilibrium. This was done with ultrasensitive differential electrostatic accelerometers onboard a drag-free satellite.
View Article and Find Full Text PDFAccording to the weak equivalence principle, all bodies should fall at the same rate in a gravitational field. The MICROSCOPE satellite, launched in April 2016, aims to test its validity at the 10^{-15} precision level, by measuring the force required to maintain two test masses (of titanium and platinum alloys) exactly in the same orbit. A nonvanishing result would correspond to a violation of the equivalence principle, or to the discovery of a new long-range force.
View Article and Find Full Text PDFWe show that light (approximately or = 1-30 MeV) dark matter particles can play a significant role in core-collapse supernovae, if they have relatively large annihilation and scattering cross sections, as compared to neutrinos. We find that if such particles are lighter than approximately or = 10 MeV and reproduce the observed dark matter relic density, supernovae would cool on a much longer time scale and would emit neutrinos with significantly smaller energies than in the standard scenario, in disagreement with observations. This constraint may be avoided, however, in certain situations for which the neutrino-dark-matter scattering cross sections remain comparatively small.
View Article and Find Full Text PDFThe goal of this study was to describe the magnetic resonance (MR) imaging signs of deeply infiltrating endometriosis (DIE) lesions and above all to find out if MR imaging can pinpoint the location of these lesions. We made a retrospective study of 8 patients presenting with histologically proven DIE lesions. The MR imaging results were compared with intraoperative findings.
View Article and Find Full Text PDFPurpose: Diagnosis of pigmented skin tumors is often difficult. The aim of the present study is to evaluate high frequency ultrasound and Doppler ultrasound in the localization and the characterization of these tumors.
Material And Methods: One hundred and seventy six pigmented skin tumors including melanocytic and non melanocytic, benign and malignant lesions have been examined before resection using high frequency ultrasound (20MHz probe) and Doppler ultrasound (13MHz probe-Doppler frequency: 7MHz).