782 research outputs found
Spin dependent fragmentation function at Belle
The measurement of the so far unknown chiral-odd quark transverse spin
distribution in either semi-inclusive DIS (SIDIS) or inclusive measurements in
pp collisions at RHIC has an additional chiral-odd fragmentation function
appearing in the cross section. These chiral-odd fragmentation functions (FF)
can for example be the so-called Collins FF or the Interference FF. HERMES has
given a first hint that these FFs are nonzero, however in order to measure the
transversity one needs these FFs to be precisely known. We have used 29.0
fb of data collected by the Belle experiment at the KEKB
collider to measure azimuthal asymmetries for different charge combinations of
pion pairs and thus access the Collins FF.Comment: Results presented at the DIS 2006 conference in Tsukuba, Japa
Spin dependent fragmentation functions at Belle
The Belle detector at the KEKB e+e− collider provides large
amounts of statistics to study the fragmentation of light quarks into final state hadrons. In addition to unpolarized fragmentation functions also spin dependent fragmentation can be studied. Belle has successfully extracted asymmetries related to the Collins and interference fagmentation functions for charged pions
Sivers effect in Drell Yan at RHIC
On the basis of a fit to the Sivers effect in deep-inelastic scattering, we
make predictions for single-spin asymmetries in the Drell-Yan process at RHIC.Comment: 10 pages, 7 figures, 1 table. v2: References and comments added,
minor correction
A Hadron Blind Detector for the PHENIX Experiment
A novel Hadron Blind Detector (HBD) has been developed for an upgrade of the
PHENIX experiment at RHIC. The HBD will allow a precise measurement of
electron-positron pairs from the decay of the light vector mesons and the
low-mass pair continuum in heavy-ion collisions. The detector consists of a 50
cm long radiator filled with pure CF4 and directly coupled in a windowless
configuration to a triple Gas Electron Multiplier (GEM) detector with a CsI
photocathode evaporated on the top face of the first GEM foil.Comment: 4 pages, 3 figures, Quark Matter 2005 conference proceeding
Test of CPT and Lorentz invariance from muonium spectroscopy
Following a suggestion of Kostelecky et al. we have evaluated a test of CPT
and Lorentz invariance from the microwave spectroscopy of muonium. Hamiltonian
terms beyond the standard model violating CPT and Lorentz invariance would
contribute frequency shifts and to
and , the two transitions involving muon spin flip, which were
precisely measured in ground state muonium in a strong magnetic field of 1.7 T.
The shifts would be indicated by anti-correlated oscillations in and
at the earth's sidereal frequency. No time dependence was found in
or at the level of 20 Hz, limiting the size of some CPT
and Lorentz violating parameters at the level of GeV,
representing Planck scale sensitivity and an order of magnitude improvement in
sensitivity over previous limits for the muon.Comment: 4 pages, 4 figures, uses REVTeX and epsf, submitted to Phys. Rev.
Let
Na Activation Level Measurements of Fused Silica Rods in the LHC Target Absorber for Neutrals (TAN) Compared to FLUKA Simulations
The Target Absorbers for Neutrals (TANs) are located in a high-intensity
radiation environment inside the tunnel of the Large Hadron Collider (LHC).
TANs are positioned about m downstream from the beam interaction points.
Seven cm long fused silica rods with different dopant specifications were
irradiated in the TAN by the Beam RAte of Neutrals (BRAN) detector group during
+ data taking from 2016 to 2018 at the LHC. The peak dose delivered to
the fused silica rods was MGy. We report measurements of the Na
activation of the fused silica rods carried out at the University of Illinois
at Urbana-Champaign and Argonne National Laboratory. At the end of the
irradiation campaign, the maximum Na activity observed was
kBq corresponding to a density, , of Na nuclei. FLUKA Monte Carlo simulations have been performed
by the CERN FLUKA team to estimate Na activities for the irradiated BRAN
rod samples. The simulations reproduce the Na activity profile measured
along the rods, with a 35% underestimation of the experimental measurement
results.Comment: 11 pages, 14 figures, to be submitted to PRA
A comparative study of Jet-quenching Schemes
The four major approximation schemes devised to study the modification of
jets in dense matter are outlined. The comparisons are restricted to basic
assumptions and approximations made in each case and the calculation
methodology used. Emergent underlying similarities between apparently disparate
methods brought about by the approximation schemes are exposed.
Parameterizations of the medium in each scheme are discussed in terms of the
transport coefficient . Discrepancies between the estimates obtained
from the four schemes are discussed. Recent developments in the basic theory
and phenomenology of energy loss are highlighted.Comment: 12 pages, 10 figures, latex, plenary presentation at the 19th
International Conference on Ultra-Relativistic Nucleus-Nucleus Collisions
(QM2006), Shanghai, China Nov. 14-20, 200
Optical Transmission Characterization of Fused Silica Materials Irradiated at the CERN Large Hadron Collider
The Target Absorbers for Neutrals (TANs) represent one of the most
radioactive regions in the Large Hadron Collider (LHC). Seven 40 cm long fused
silica rods with different dopant specifications, manufactured by Heraeus, were
irradiated in one of the TANs located around the ATLAS experiment by the Beam
RAte of Neutrals (BRAN) detector group. This campaign took place during the Run
2 p+p data taking, which occurred between 2016 and 2018. This paper reports a
complete characterization of optical transmission per unit length of irradiated
fused silica materials as a function of wavelength (240 nm - 1500 nm), dose (up
to 18 MGy), and level of OH and H dopants introduced in the manufacturing
process. The dose delivered to the rods was estimated using Monte Carlo
simulations performed by the CERN FLUKA team.Comment: 29 pages, 15 figures, to be submitted to NIM-
The RHIC Spin Program: Achievements and Future Opportunities
This document summarizes recent achievements of the RHIC spin program and
their impact on our understanding of the nucleon's spin structure, i.e. the
individual parton (quark and gluon) contributions to the helicity structure of
the nucleon and to understand the origin of the transverse spin phenomena. Open
questions are identified and a suite of future measurements with polarized
beams at RHIC to address them is laid out. Machine and detector requirements
and upgrades are briefly discussed
Search for Lorentz and CPT Violation Effects in Muon Spin Precession
The spin precession frequency of muons stored in the storage ring has
been analyzed for evidence of Lorentz and CPT violation. Two Lorentz and CPT
violation signatures were searched for: a nonzero
(=); and a sidereal variation of
. No significant effect is found, and the following
limits on the standard-model extension parameters are obtained: GeV; GeV; and the 95% confidence level limits
GeV and
GeV.Comment: 5 pages, 3 figures, submitted to Physical Review Letters, Modified to
answer the referees suggestion
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