Search results for "IPR"
showing 10 items of 1515 documents
Laser cooling of relativistic heavy-ion beams for FAIR
2015
Laser cooling is a powerful technique to reduce the longitudinal momentum spread of stored relativistic ion beams. Based on successful experiments at the experimental storage ring at GSI in Darmstadt, of which we show some important results in this paper, we present our plans for laser cooling of relativistic ion beams in the future heavy-ion synchrotron SIS100 at the Facility for Antiproton and Ion Research in Darmstadt.
Penning traps as a versatile tool for precise experiments in fundamental physics
2009
This review article describes the trapping of charged particles. The main principles of electromagnetic confinement of various species from elementary particles to heavy atoms are briefly described. The preparation and manipulation with trapped single particles, as well as methods of frequency measurements, providing unprecedented precision, are discussed. Unique applications of Penning traps in fundamental physics are presented. Ultra-precise trap-measurements of masses and magnetic moments of elementary particles (electrons, positrons, protons and antiprotons) confirm CPT-conservation, and allow accurate determination of the fine-structure constant alpha and other fundamental constants. T…
Orbital origin and matrix element effects in the Ag/Si(111)-()R30° Fermi surface
2007
The Fermi surface (FS) of the Ag/Si(1 1 1)-3×3 reconstruction with an excess of Ag has been mapped by angle resolved photoemission spectroscopy with polarized light in a wide region of the reciprocal space and with different detection geometries. In contrast to previous results, a strong polarization dependence is observed. Applying the dipole selection rules, it is found that the surface state at the Fermi level, S1 state, has odd symmetry with respect to the mirror plane of the honeycomb-chained triangle structure, indicating that it is mainly derived from Ag 5px and 5py orbitals. This conclusion is revised in the new frame of a inequivalent-triangle structure for the Ag/Si(1 1 1)-3×3 at …
Development of integrated superconducting quadrupole doublet modules for operation in the SIS100 accelerator
2015
The FAIR project (Facility for Antiproton and Ion Research) evolves and builds an international accelerator- and experimental facility for basic research activities in various fields of modern physics. Within the course of this project, integrated quadrupole doublet modules are in development. The quadrupole doublet modules provide a pair of superconducting main quadrupoles (focusing and defocusing), corrector magnets, cryogenic collimators and beam position monitors as integrated sets of ion-optical elements. Furthermore LHe cooled beam pipes and vacuum cold-warm transitions are used as ultra-high vacuum components for beam transportation. Superconducting bus bars are used for 13 kA curren…
Two-nucleon mechanism for antiproton annihilation in nuclei
1986
Abstract The annihilation probability of an antiproton inside a nucleus is evaluated via the p NN → N n π reaction. For that purpose the p N→( n +1)π reaction is started from and one of the pions is allowed to be virtual, carrying the appropriate energy and momentum to produce physical particle-hole excitations. The new mechanism proves to be very important: at nuclear densities around ϱ = 0.2 ϱ 0 it has about the same strength as the one-nucleon annihilation mechanism, and becomes much more important as the nuclear density increases. The repercussion of the new channel in the p -nucleus annihilation cross section is studied and its relevance in p atoms and p -nucleus elastic scattering is …
A precise measurement of the real part of the elastic scattering amplitude at the Sp̄pS
1993
Abstract A precise measurement of pp elastic scattering in the Coulomb-strong interaction interference region was performed at the CERN SppS Collider at a centre-of-mass energy of 541 GeV. The ratio of the real to the imaginary part of the forward elastic scattering amplitude was found to be ρ = 0.135 ± 0.015. The slope of the exponential fall off of the strong interaction part was also measured to be b = 15.5 ± 0.1 GeV −2 .
Measurements of the antiproton-proton elastic cross section in the beam momentum range between 180 and 600 MeV/c
1991
The differential cross section for antiproton-proton elastic scattering has been measured for the beam momenta between 180 and 600 MeV/c. The real-to-imaginary ratio of the forward elastic scattering amplitude is derived from the Coulomb-nuclear interference. The ratio is found to be close to zero between 180 and 500 MeV/c with a minimum ofρ=−0.14 at 260 MeV/c. This result is contrary to model predictions. The phase shifts for thes-,p- andd-waves are extracted. The partial wave compositions of the elastic and inelastic cross sections have been determined. A large contribution of thep-wave is identified in the antiproton-proton interactions at small momenta.
Co-Rotating Beams of Antiprotons and H- in LEAR and High Resolution Spectroscopy of pp̄ Atoms in Flight
1984
Beams of pp atoms flighting in vacuum with adjustable velocity have been proposed to study the spectroscopy of protonium atoms with high energy resolution (Ae/E down to 10-5) by using differential absorber foils and conventional X-ray detectors for emission spectroscopy and fixed frequency high power radiation sources for induced spectroscopy1. This aproach would lead to an improvement by more than two orders of magnitude versus the possibilities of “conventional” experiments in the field of protonium planned at LEAR2, and would give ways to measure with high accuracy effects of electromagnetic and strong interactions on the atomic levels of protonium.
Radiative Recombination in a Strong Laser Field
2006
Recent advances of radiative recombination in the presence of strong laser fields are reported. The intense laser radiation is found to introduce new relevant features, among which enhancement and control of the emitted X-ray spectra are the most important. The influence of the plasma medium in which the process generally takes place is considered as well. The results of the recent investigations shed new light on the laser assisted radiative recombination physics and give relevant indications concerning the possibilities to have effective slow electrons and to balance the plasma heating, as needed in important applications.
Minkowskian description of polarized light and polarizers.
2002
A conventional Stokes description of polarized light is considered in a four-dimensional Lorentzian space, developing a seminal idea of Paul Soleillet [Ann. Phys. (Paris) 12, 23 (1929)]. This provides a striking interpretation for the degree of polarization and the Stokes decomposition of light beams. Malus law and reciprocity theorems for polarizers are studied using this Lorentzian formalism.