1,062 research outputs found
Magnetic coupling to the Advanced Virgo payloads and its impact on the low frequency sensitivity
We study the electromagnetic coupling of the Advanced Virgo (AdV) Input
Mirror Payload (IMP) in response to a slowly time-varying magnetic field. As
the problem is not amenable to analytical solution, we employ and validate a
finite element (FE) analysis approach. The FE model is built to represent as
faithfully as possible the real object and it has been validated by comparison
with experimental measurements. The intent is to estimate the induced currents
and the magnetic field in the neighbourhood of the payload. The procedure found
21 equivalent electrical configurations that are compatible with the
measurements. These have been used to compute the magnetic noise contribution
to the total AdV strain noise. At the current stage of development AdV seems to
be unaffected by magnetic noise, but we foresee a non-negligible coupling once
AdV reaches the design sensitivity.Comment: 8 pages, 8 figures, 2 table
Status of the Super-B factory Design
The SuperB international team continues to optimize the design of an
electron-positron collider, which will allow the enhanced study of the origins
of flavor physics. The project combines the best features of a linear collider
(high single-collision luminosity) and a storage-ring collider (high repetition
rate), bringing together all accelerator physics aspects to make a very high
luminosity of 10 cm sec. This asymmetric-energy collider
with a polarized electron beam will produce hundreds of millions of B-mesons at
the (4S) resonance. The present design is based on extremely low
emittance beams colliding at a large Piwinski angle to allow very low
without the need for ultra short bunches. Use of crab-waist
sextupoles will enhance the luminosity, suppressing dangerous resonances and
allowing for a higher beam-beam parameter. The project has flexible beam
parameters, improved dynamic aperture, and spin-rotators in the Low Energy Ring
for longitudinal polarization of the electron beam at the Interaction Point.
Optimized for best colliding-beam performance, the facility may also provide
high-brightness photon beams for synchrotron radiation applications
Insertion Magnets
Chapter 3 in High-Luminosity Large Hadron Collider (HL-LHC) : Preliminary
Design Report. 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.Comment: 19 pages, Chapter 3 in High-Luminosity Large Hadron Collider (HL-LHC)
: Preliminary Design Repor
\b{eta}-delayed three-proton decay of 31Ar
The beta decay of 31Ar, produced by fragmentation of a 36Ar beam at 880
MeV/nucleon, was investigated. Identified ions of 31Ar were stopped in a
gaseous time projection chamber with optical readout allowing to record decay
events with emission of protons. In addition to \b{eta}-delayed emission of one
and two protons we have clearly observed the beta-delayed three-proton branch.
The branching ratio for this channel in 31Ar is found to be 0.07(2)%.Comment: 5 pages, 3 figures, submitted to Physical Rev.
Schottky mass measurements of heavy neutron-rich nuclides in the element range 70\leZ \le79 at the ESR
Storage-ring mass spectrometry was applied to neutron-rich Au
projectile fragments. Masses of Lu, Hf, Ta,
W, and Re nuclei were measured for the first time. The
uncertainty of previously known masses of W and Os nuclei
was improved. Observed irregularities on the smooth two-neutron separation
energies for Hf and W isotopes are linked to the collectivity phenomena in the
corresponding nuclei.Comment: 10 pages, 9 figures, 2 table
Discovery and Cross-Section Measurement of Neutron-Rich Isotopes in the Element Range from Neodymium to Platinum at the FRS
With a new detector setup and the high-resolution performance of the fragment
separator FRS at GSI we discovered 57 new isotopes in the atomic number range
of 60: \nuc{159-161}{Nb}, \nuc{160-163}{Pm}, \nuc{163-166}Sm,
\nuc{167-168}{Eu}, \nuc{167-171}{Gd}, \nuc{169-171}{Tb}, \nuc{171-174}{Dy},
\nuc{173-176}{Ho}, \nuc{176-178}{Er}, \nuc{178-181}{Tm}, \nuc{183-185}{Yb},
\nuc{187-188}{Lu}, \nuc{191}{Hf}, \nuc{193-194}{Ta}, \nuc{196-197}{W},
\nuc{199-200}{Re}, \nuc{201-203}{Os}, \nuc{204-205}{Ir} and \nuc{206-209}{Pt}.
The new isotopes have been unambiguously identified in reactions with a
U beam impinging on a Be target at 1 GeV/u. The isotopic production
cross-section for the new isotopes have been measured and compared with
predictions of different model calculations. In general, the ABRABLA and COFRA
models agree better than a factor of two with the new data, whereas the
semiempirical EPAX model deviates much more. Projectile fragmentation is the
dominant reaction creating the new isotopes, whereas fission contributes
significantly only up to about the element holmium.Comment: 9 pages, 4 figure
Reconstruction of the gravitational wave signal during the Virgo science runs and independent validation with a photon calibrator
The Virgo detector is a kilometer-scale interferometer for gravitational wave
detection located near Pisa (Italy). About 13 months of data were accumulated
during four science runs (VSR1, VSR2, VSR3 and VSR4) between May 2007 and
September 2011, with increasing sensitivity.
In this paper, the method used to reconstruct, in the range 10 Hz-10 kHz, the
gravitational wave strain time series from the detector signals is
described. The standard consistency checks of the reconstruction are discussed
and used to estimate the systematic uncertainties of the signal as a
function of frequency. Finally, an independent setup, the photon calibrator, is
described and used to validate the reconstructed signal and the
associated uncertainties.
The uncertainties of the time series are estimated to be 8% in
amplitude. The uncertainty of the phase of is 50 mrad at 10 Hz with a
frequency dependence following a delay of 8 s at high frequency. A bias
lower than and depending on the sky direction of the GW is
also present.Comment: 35 pages, 16 figures. Accepted by CQ
Evidence of dynamical dipole excitation in the fusion-evaporation of the 40Ca +152Sm heavy system
The excitation of the dynamical dipole mode along the fusion path was investigated for the first time
in the formation of a heavy compound nucleus in the
A
âŒ
190 mass region. The compound nucleus was
formed at identical conditions of excitation energy and spin from two entrance channels: the charge-asymmetric
40
Ca
+
152
Sm and the nearly charge-symmetric
48
Ca
+
144
Sm at
E
lab
=
11 and 10.1 MeV
/
nucleon, respectively.
High-energy
Îł
rays and light charged particles were measured in coincidence with evaporation residues by
means of the MEDEA multidetector array (Laboratori Nazionali del Sud, Italy) coupled to four parallel plate
avalanche counters. The charged particle multiplicity spectra and angular distributions were used to pin down
the average excitation energy, the average mass, and the average charge of the compound nucleus. The
Îł
-ray
multiplicity spectrum and angular distribution related to the nearly charge-symmetric channel were employed to
obtain new data on the giant dipole resonance in the compound nucleus. The dynamical dipole mode excitation in
the charge-asymmetric channel was evidenced, in a model-independent way, by comparing the
Îł
-ray multiplicity
spectra and angular distributions of the two entrance channels with each other. Calculations of the dynamical
dipole mode in the
40
Ca
+
152
Sm channel, based on a collective bremsstrahlung analysis of the reaction dynamics,
are presented. Possible interesting implications in the superheavy-element quest are discussed
Gravitational Waves From Known Pulsars: Results From The Initial Detector Era
We present the results of searches for gravitational waves from a large selection of pulsars using data from the most recent science runs (S6, VSR2 and VSR4) of the initial generation of interferometric gravitational wave detectors LIGO (Laser Interferometric Gravitational-wave Observatory) and Virgo. We do not see evidence for gravitational wave emission from any of the targeted sources but produce upper limits on the emission amplitude. We highlight the results from seven young pulsars with large spin-down luminosities. We reach within a factor of five of the canonical spin-down limit for all seven of these, whilst for the Crab and Vela pulsars we further surpass their spin-down limits. We present new or updated limits for 172 other pulsars (including both young and millisecond pulsars). Now that the detectors are undergoing major upgrades, and, for completeness, we bring together all of the most up-to-date results from all pulsars searched for during the operations of the first-generation LIGO, Virgo and GEO600 detectors. This gives a total of 195 pulsars including the most recent results described in this paper.United States National Science FoundationScience and Technology Facilities Council of the United KingdomMax-Planck-SocietyState of Niedersachsen/GermanyAustralian Research CouncilInternational Science Linkages program of the Commonwealth of AustraliaCouncil of Scientific and Industrial Research of IndiaIstituto Nazionale di Fisica Nucleare of ItalySpanish Ministerio de Economia y CompetitividadConselleria d'Economia Hisenda i Innovacio of the Govern de les Illes BalearsNetherlands Organisation for Scientific ResearchPolish Ministry of Science and Higher EducationFOCUS Programme of Foundation for Polish ScienceRoyal SocietyScottish Funding CouncilScottish Universities Physics AllianceNational Aeronautics and Space AdministrationOTKA of HungaryLyon Institute of Origins (LIO)National Research Foundation of KoreaIndustry CanadaProvince of Ontario through the Ministry of Economic Development and InnovationNational Science and Engineering Research Council CanadaCarnegie TrustLeverhulme TrustDavid and Lucile Packard FoundationResearch CorporationAlfred P. Sloan FoundationAstronom
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