740 research outputs found
Physics opportunities with future proton accelerators at CERN
We analyze the physics opportunities that would be made possible by upgrades
of CERN's proton accelerator complex. These include the new physics possible
with luminosity or energy upgrades of the LHC, options for a possible future
neutrino complex at CERN, and opportunities in other physics including rare
kaon decays, other fixed-target experiments, nuclear physics and antiproton
physics, among other possibilities. We stress the importance of inputs from
initial LHC running and planned neutrino experiments, and summarize the
principal detector R&D issues.Comment: 39 page, word document, full resolution version available from
http://cern.ch/pofpa/POFPA-arXive.pd
Molecular tendrils feeding star formation in the Eye of the Medusa - The Medusa merger in high resolution 12CO 2-1 maps
Studying molecular gas properties in merging galaxies gives us important
clues to the onset and evolution of interaction-triggered starbursts. NGC4194
is particularly interesting to study since its FIR-to-CO luminosity ratio
rivals that of ULIRGs,despite its lower luminosity compared to ULIRGs, which
indicates a high star formation efficiency that is relative to even most
spirals and ULIRGs.We study the molecular medium at an angular resolution of
0.65"x .52" through our observations of CO2-1 emission using the SMA. We
compare our CO2-1 maps with optical HST and high angular resolution radio
continuum images to study the relationship between molecular gas and other
components of the starburst region. The molecular gas is tracing the
complicated dust lane structure of NGC4194 with the brightest emission being
located in an off-nuclear ring-like structure with ~320pc radius, the Eye of
the Medusa. The bulk CO emission of the ring is found south of the kinematical
center of NGC4194. The northern tip of the ring is associated with the galaxy
nucleus, where the radio continuum has its peak. A prominent, secondary
emission maximum in the radio continuum is located inside the molecular ring.
This suggests that the morphology of the ring is partially influenced by
massive supernova explosions. From the combined evidence, we propose that the
Eye of the Medusa contains a shell of swept up material where we identify a
number of giant molecular associations. We propose that the Eye may be the site
of an efficient starburst of 5-7M_sun/yr, but it would still constitute only a
fraction of the 30-50M_sun/yr SFR of NGC4194. Furthermore, we find that ~50% of
the molecular mass of NGC4194 is found in extended filamentary-like structures
tracing the minor and major axis dust lanes. We suggest that molecular gas is
transported along these lanes providing the central starburst region with fuel.Comment: accepted for publication in A&A, 12 pages, 9 figure
How different Fermi surface maps emerge in photoemission from Bi2212
We report angle-resolved photoemission spectra (ARPES) from the Fermi energy
() over a large area of the () plane using 21.2 eV and 32 eV
photons in two distinct polarizations from an optimally doped single crystal of
BiSrCaCuO (Bi2212), together with extensive
first-principles simulations of the ARPES intensities. The results display a
wide-ranging level of accord between theory and experiment and clarify how
myriad Fermi surface (FS) maps emerge in ARPES under various experimental
conditions. The energy and polarization dependences of the ARPES matrix element
help disentangle primary contributions to the spectrum due to the pristine
lattice from those arising from modulations of the underlying tetragonal
symmetry and provide a route for separating closely placed FS sheets in low
dimensional materials.Comment: submitted to PR
EURISOL High Power Targets
Modern Nuclear Physics requires access to higher yields of rare isotopes, that relies on further development of the In-flight and Isotope Separation On-Line (ISOL) production methods. The limits of the In-Flight method will be applied via the next generation facilities FAIR in Germany, RIKEN in Japan and RIBF in the USA. The ISOL method will be explored at facilities including ISAC-TRIUMF in Canada, SPIRAL-2 in France, SPES in Italy, ISOLDE at CERN and eventually at the very ambitious multi-MW EURISOL facility. ISOL and in-flight facilities are complementary entities. While in-flight facilities excel in the production of very short lived radioisotopes independently of their chemical nature, ISOL facilities provide high Radioisotope Beam (RIB) intensities and excellent beam quality for 70 elements. Both production schemes are opening vast and rich fields of nuclear physics research. In this article we will introduce the targets planned for the EURISOL facility and highlight some of the technical and safety challenges that are being addressed. The EURISOL Radioactive Ion Beam production relies on three 100 kW target stations and a 4 MW converter target station, and aims at producing orders of magnitude higher intensities of approximately one thousand different radioisotopes currently available, and to give access to new rare isotopes. As an illustrative example of its potential, beam intensities of the order of 1013 132Sn ions pe r second will be available from EURISOL, providing ideal primary beams for further fragmentation or fusion reactions studies
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