1,163 research outputs found
Perspectives in Neutrino Physics: Monochromatic Neutrino Beams
In the last few years spectacular results have been achieved with the
demonstration of non vanishing neutrino masses and flavour mixing. The ultimate
goal is the understanding of the origin of these properties from new physics.
In this road, the last unknown mixing must be determined. If it is
proved to be non-zero, the possibility is open for Charge Conjugation-Parity
(CP) violation in the lepton sector. This will require precision experiments
with a very intense neutrino source. Here a novel method to create a
monochromatic neutrino beam, an old dream for neutrino physics, is proposed
based on the recent discovery of nuclei that decay fast through electron
capture. Such nuclei will generate a monochromatic directional neutrino beam
when decaying at high energy in a storage ring with long straight sections. We
also show that the capacity of such a facility to discover new physics is
impressive, so that fine tuning of the boosted neutrino energy allows precision
measurements of the oscillation parameters even for a mixing as
small as 1 degree. We can thus open a window to the discovery of CP violation
in neutrino oscillations.Comment: 15 pages, 7 figures. Contribution to the proceedings of GUSTAVOFEST -
Symposium in Honour of Gustavo C. Branco: CP Violation and the Flavour
Puzzle, Lisbon, Portugal, 19-20 July 200
Physics Reach with a Monochromatic Neutrino Beam from Electron Capture
Neutrino oscillation experiments from different sources have demonstrated
non-vanishing neutrino masses and flavour mixings. The next experiments have to
address the determination of the connecting mixing U(e3) and the existence of
the CP violating phase. Whereas U(e3) measures the strength of the oscillation
probability in appearance experiments, the CP phase acts as a phase-shift in
the interference pattern. Here we propose to separate these two parameters by
energy dependence, using the novel idea of a monochromatic neutrino beam
facility based on the acceleration of ions that decay fast through electron
capture. Fine tuning of the boosted neutrino energy allows precision
measurements able to open a window for the discovery of CP violation, even for
a mixing as small as 1 degree.Comment: 4 pages, 1 figure. Talk given at the International Europhysics
Conference on High Energy Physics, HEP-EPS 2005, Lisbon, Portugal, July
21-27, 200
Upgrading of the Air-conditioning of the Computer Room in the Computer Centre for the LHC era
Built in the beginning of 1970's, the Computer Centre air-conditioning and cooling systems were designed to be modular and easily adaptable to the unpredictable future needs of computing. The infrastructure of LHC-computing that will be housed in the existing Computer Room with its five Computing farms and over 11000 PC's increases the requirements of cooling and air-conditioning power to a new level. The nominal thermal loads from the equipment rise from the current design maximum of 1MW to estimated maximum of 2MW in the future. This paper presents calculations and proposes solutions to meet the new nominal requirements. The air-conditioning system must also be able to cope with a situation of power cut in the main supply. A calculation of the temperature evolution during the power cut and a justified operation strategy for this scenario is also presented
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
Physics and optimization of beta-beams: From low to very high gamma
The physics potential of beta beams is investigated from low to very high
gamma values and it is compared to superbeams and neutrino factories. The gamma
factor and the baseline are treated as continuous variables in the optimization
of the beta beam, while a fixed mass water Cherenkov detector or a totally
active scintillator detector is assumed. We include in our discussion also the
gamma dependence of the number of ion decays per year. For low gamma, we find
that a beta beam could be a very interesting alternative to a superbeam
upgrade, especially if it is operated at the second oscillation maximum to
reduce correlations and degeneracies. For high gamma, we find that a beta beam
could have a potential similar to a neutrino factory. In all cases, the
sensitivity of the beta beams to CP violation is very impressive if similar
neutrino and anti-neutrino event rates can be achieved.Comment: 34 pages, 16 figures, Fig. 2 modified, discussion improved, refs.
added, version to appear in PR
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
Antineutrino induced antikaon production off the nucleon
The charged current antikaon production off nucleons induced by antineutrinos
is studied at low and intermediate energies. We extend here our previous
calculation on kaon production induced by neutrinos. We have developed a
microscopic model that starts from the SU(3) chiral Lagrangians and includes
background terms and the resonant mechanisms associated to the lowest lying
resonance in the channel, namely, the Sigma*(1385). Our results could be of
interest for the background estimation of various neutrino oscillation
experiments like MiniBooNE and SuperK. They can also be helpful for the planned
antineutrino experiments like MINERvA, NOvA and T2K phase II and for beta-beam
experiments with antineutrino energies around 1 GeV.Comment: 15 pages and 6 figures. This version matches accepted version for
publication in Physical Review
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
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