118 research outputs found
Peculiarities of pinning and microwave absorption hysteresis in thin superconducting films
The results of experimental and theoretical studies of the hysteretic microwave absorption (MWA) in the superconducting Bi2Sr 2CaCu2O8 thin films are presented. It has been found experimentally that the hysteresis loop manifests some unusual features such as the non-monotone hysteresis variation and the change of a hysteresis sign. We have shown that such unusual behavior is due to the special nature of the bulk pinning in a superconducting film with a thickness comparable with the field penetration depth. The theoretical model of the MWA hysteresis has been developed taking into account the inhomogeneous distribution of centers with different symmetry of a pinning potential and their variation with the magnetic field value. © Springer Science+Business Media, LLC 2006
Localized charged states and phase separation near second order phase transition
Localized charged states and phase segregation are described in the framework
of the phenomenological Ginzburg-Landau theory of phase transitions. The
Coulomb interactions determines the charge distribution and the characteristic
length of the phase separated states. The phase separation with charge
segregation becomes possible because of the large dielectric constant and the
small density of extra charge in the range of charge localization. The phase
diagram is calculated and the energy gain of the phase separated state is
estimated. The role of the Coulomb interaction is elucidated
Progress with the Upgrade of the SPS for the HL-LHC Era
The demanding beam performance requirements of the High Luminosity (HL-) LHC
project translate into a set of requirements and upgrade paths for the LHC
injector complex. In this paper the performance requirements for the SPS and
the known limitations are reviewed in the light of the 2012 operational
experience. The various SPS upgrades in progress and still under consideration
are described, in addition to the machine studies and simulations performed in
2012. The expected machine performance reach is estimated on the basis of the
present knowledge, and the remaining decisions that still need to be made
concerning upgrade options are detailed.Comment: 3 p. Presented at 4th International Particle Accelerator Conference
(IPAC 2013
The LBNO long-baseline oscillation sensitivities with two conventional neutrino beams at different baselines
The proposed Long Baseline Neutrino Observatory (LBNO) initially consists of
kton liquid double phase TPC complemented by a magnetised iron
calorimeter, to be installed at the Pyh\"asalmi mine, at a distance of 2300 km
from CERN. The conventional neutrino beam is produced by 400 GeV protons
accelerated at the SPS accelerator delivering 700 kW of power. The long
baseline provides a unique opportunity to study neutrino flavour oscillations
over their 1st and 2nd oscillation maxima exploring the behaviour, and
distinguishing effects arising from and matter. In this paper we
show how this comprehensive physics case can be further enhanced and
complemented if a neutrino beam produced at the Protvino IHEP accelerator
complex, at a distance of 1160 km, and with modest power of 450 kW is aimed
towards the same far detectors. We show that the coupling of two independent
sub-MW conventional neutrino and antineutrino beams at different baselines from
CERN and Protvino will allow to measure CP violation in the leptonic sector at
a confidence level of at least for 50\% of the true values of
with a 20 kton detector. With a far detector of 70 kton, the
combination allows a sensitivity for 75\% of the true values of
after 10 years of running. Running two independent neutrino
beams, each at a power below 1 MW, is more within today's state of the art than
the long-term operation of a new single high-energy multi-MW facility, which
has several technical challenges and will likely require a learning curve.Comment: 21 pages, 12 figure
Machine layout and performance
The Large Hadron Collider (LHC) is one of the largest scientific instruments ever built. Since opening up a new
energy frontier for exploration in 2010, it has gathered a global user community of about 7,000 scientists working
in fundamental particle physics and the physics of hadronic matter at extreme temperature and density. To sustain
and extend its discovery potential, the LHC will need a major upgrade in the 2020s. This will increase its luminosity
(rate of collisions) by a factor of five beyond the original design value and the integrated luminosity (total
collisions created) by a factor ten. The LHC is already a highly complex and exquisitely optimised machine so this
upgrade must be carefully conceived and will require about ten years to implement. The new configuration, known
as High Luminosity LHC (HL-LHC), will rely on a number of key innovations that push accelerator technology
beyond its present limits. Among these are cutting-edge 11-12 tesla superconducting magnets, compact superconducting
cavities for beam rotation with ultra-precise phase control, new technology and physical processes
for beam collimation and 300 metre-long high-power superconducting links with negligible energy dissipation.
The present document describes the technologies and components that will be used to realise the project and is
intended to serve as the basis for the detailed engineering design of HL-LHC
A primary electron beam facility at CERN -- eSPS Conceptual design report
The design of a primary electron beam facility at CERN is described. The
study has been carried out within the framework of the wider Physics Beyond
Colliders study. It re-enables the Super Proton Synchrotron (SPS) as an
electron accelerator, and leverages the development invested in Compact Linear
Collider (CLIC) technology for its injector and as an accelerator research and
development infrastructure. The facility would be relevant for several of the
key priorities in the 2020 update of the European Strategy for Particle
Physics, such as an electron-positron Higgs factory, accelerator R\&D, dark
sector physics, and neutrino physics. In addition, it could serve experiments
in nuclear physics. The electron beam delivered by this facility would provide
access to light dark matter production significantly beyond the targets
predicted by a thermal dark matter origin, and for natures of dark matter
particles that are not accessible by direct detection experiments. It would
also enable electro-nuclear measurements crucial for precise modelling the
energy dependence of neutrino-nucleus interactions, which is needed to
precisely measure neutrino oscillations as a function of energy. The
implementation of the facility is the natural next step in the development of
X-band high-gradient acceleration technology, a key technology for compact and
cost-effective electron/positron linacs. It would also become the only facility
with multi-GeV drive bunches and truly independent electron witness bunches for
plasma wakefield acceleration. A second phase capable to deliver positron
witness bunches would make it a complete facility for plasma wakefield collider
studies. [...
OPERATIONAL PERFORMANCE OF THE LHC PROTON BEAMS WITH THE SPS LOW TRANSITION ENERGY OPTICS
Abstract An optics in the SPS with lower integer tunes (20 versus 26) was proposed and introduced in machine studies since 2010, as a measure for increasing transverse and longitudinal instability thresholds, especially at low energy, for the LHC proton beams. After two years of machine studies and careful optimisation, the new Q20 optics became operational in September 2012 and steadily delivered beam to the LHC until the end of the run. This paper reviews the operational performance of the Q20 optics with respect to transverse and longitudinal beam characteristics in the SPS, enabling high brightness beams injected into the LHC. Aspects of longitudinal beam stability, transmission, high-energy orbit control and beam transfer are discussed
OPERATIONAL PERFORMANCE OF THE LHC PROTON BEAMS WITH THE SPS LOW TRANSITION ENERGY OPTICS
Abstract An optics in the SPS with lower integer tunes (20 versus 26) was proposed and introduced in machine studies since 2010, as a measure for increasing transverse and longitudinal instability thresholds, especially at low energy, for the LHC proton beams. After two years of machine studies and careful optimisation, the new Q20 optics became operational in September 2012 and steadily delivered beam to the LHC until the end of the run. This paper reviews the operational performance of the Q20 optics with respect to transverse and longitudinal beam characteristics in the SPS, enabling high brightness beams injected into the LHC. Aspects of longitudinal beam stability, transmission, high-energy orbit control and beam transfer are discussed
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