The magnetic fields and dynamical processes in the solar polar regions play a crucial role in the solar magnetic cycle and in supplying mass and energy to the fast solar wind,ultimately being vital in controlling sola...The magnetic fields and dynamical processes in the solar polar regions play a crucial role in the solar magnetic cycle and in supplying mass and energy to the fast solar wind,ultimately being vital in controlling solar activities and driving space weather.Despite numerous efforts to explore these regions,to date no imaging observations of the Sun's poles have been achieved from vantage points out of the ecliptic plane,leaving their behavior and evolution poorly understood.This observation gap has left three top-level scientific questions unanswered:How does the solar dynamo work and drive the solar magnetic cycle?What drives the fast solar wind?How do space weather processes globally originate from the Sun and propagate throughout the solar system?The Solar Polarorbit Observatory(SPO)mission,a solar polar exploration spacecraft,is proposed to address these three unanswered scientific questions by imaging the Sun's poles from high heliolatitudes.In order to achieve its scientific goals,SPO will carry six remote-sensing and four in-situ instruments to measure the vector magnetic fields and Doppler velocity fields in the photosphere,to observe the Sun in the extreme ultraviolet,X-ray,and radio wavelengths,to image the corona and the heliosphere up to 45 R_(s),and to perform in-situ detection of magnetic fields,and low-and high-energy particles in the solar wind.The SPO mission is capable of providing critical vector magnetic fields and Doppler velocities of the polar regions to advance our understanding of the origin of the solar magnetic cycle,providing unprecedented imaging observations of the solar poles alongside in-situ measurements of charged particles and magnetic fields from high heliolatitudes to unveil the mass and energy supply that drive the fast solar wind,and providing observational constraints for improving our ability to model and predict the three-dimensional(3D)structures and propagation of space weather events.展开更多
The GRAAL experimental set-up consists of a polarized and tagged photon beam that covers an energy range from a minimum of 600 MeV up to a maximum of 1500 MeV, of a liquid Hydrogen or Deuterium target and of the 4π L...The GRAAL experimental set-up consists of a polarized and tagged photon beam that covers an energy range from a minimum of 600 MeV up to a maximum of 1500 MeV, of a liquid Hydrogen or Deuterium target and of the 4π Lagrange detector optimized for photon detection. It allows the study of pseudo-scalar and vector meson photoproduCtion on the nucleon in the energy range corresponding to the second and the third resonance regions. In the following, the ∑ beam asymmetries in η and π0 photoproduction on quasi-free nucleon are shown. Also single and double polarization observables in K＋A photoproduction on free proton are shown; they are important to confirm the role of new or poorly known resonances in the 1900 MeV mass region.展开更多
文摘The magnetic fields and dynamical processes in the solar polar regions play a crucial role in the solar magnetic cycle and in supplying mass and energy to the fast solar wind,ultimately being vital in controlling solar activities and driving space weather.Despite numerous efforts to explore these regions,to date no imaging observations of the Sun's poles have been achieved from vantage points out of the ecliptic plane,leaving their behavior and evolution poorly understood.This observation gap has left three top-level scientific questions unanswered:How does the solar dynamo work and drive the solar magnetic cycle?What drives the fast solar wind?How do space weather processes globally originate from the Sun and propagate throughout the solar system?The Solar Polarorbit Observatory(SPO)mission,a solar polar exploration spacecraft,is proposed to address these three unanswered scientific questions by imaging the Sun's poles from high heliolatitudes.In order to achieve its scientific goals,SPO will carry six remote-sensing and four in-situ instruments to measure the vector magnetic fields and Doppler velocity fields in the photosphere,to observe the Sun in the extreme ultraviolet,X-ray,and radio wavelengths,to image the corona and the heliosphere up to 45 R_(s),and to perform in-situ detection of magnetic fields,and low-and high-energy particles in the solar wind.The SPO mission is capable of providing critical vector magnetic fields and Doppler velocities of the polar regions to advance our understanding of the origin of the solar magnetic cycle,providing unprecedented imaging observations of the solar poles alongside in-situ measurements of charged particles and magnetic fields from high heliolatitudes to unveil the mass and energy supply that drive the fast solar wind,and providing observational constraints for improving our ability to model and predict the three-dimensional(3D)structures and propagation of space weather events.
基金Supported by ESRF as a host institution and to the members of the CRG support group
文摘The GRAAL experimental set-up consists of a polarized and tagged photon beam that covers an energy range from a minimum of 600 MeV up to a maximum of 1500 MeV, of a liquid Hydrogen or Deuterium target and of the 4π Lagrange detector optimized for photon detection. It allows the study of pseudo-scalar and vector meson photoproduCtion on the nucleon in the energy range corresponding to the second and the third resonance regions. In the following, the ∑ beam asymmetries in η and π0 photoproduction on quasi-free nucleon are shown. Also single and double polarization observables in K＋A photoproduction on free proton are shown; they are important to confirm the role of new or poorly known resonances in the 1900 MeV mass region.
