34 research outputs found
Large enhancement of deuteron polarization with frequency modulated microwaves
We report a large enhancement of 1.7 in deuteron polarization up to values of
0.6 due to frequency modulation of the polarizing microwaves in a two liters
polarized target using the method of dynamic nuclear polarization. This target
was used during a deep inelastic polarized muon-deuteron scattering experiment
at CERN. Measurements of the electron paramagnetic resonance absorption spectra
show that frequency modulation gives rise to additional microwave absorption in
the spectral wings. Although these results are not understood theoretically,
they may provide a useful testing ground for the deeper understanding of
dynamic nuclear polarization.Comment: 10 pages, including the figures coming in uuencoded compressed tar
files in poltar.uu, which also brings cernart.sty and crna12.sty files neede
Polarised quark distributions in the nucleon from semi-inclusive spin asymmetries
We present a measurement of semi-inclusive spin asymmetries for positively and negatively charged hadrons from deep inelastic scattering of polarised muons on polarised protons and deuterons in the range 1~GeV. Compared to our previous publication on this subject, with the new data the statistical errors have been reduced by nearly a factor of two. From these asymmetries and our inclusive spin asymmetries we determine the polarised quark distributions of valence quarks and non-strange sea quarks at =10~GeV. The polarised valence quark distribution, , is positive and the polarisation increases with . The polarised valence quark distribution, , is negative and the non-strange sea distribution, , is consistent with zero over the measured range of . We find for the first moments , and , where we assumed . We also determine for the first time the second moments of the valence distributions .We present a measurement of semi-inclusive spin asymmetries for positively and negatively charged hadrons from deep inelastic scattering of polarised muons on polarised protons and deuterons in the range 1 GeV. Compared to our previous publication on this subject, with the new data the statistical errors have been reduced by nearly a factor of two. From these asymmetries and our inclusive spin asymmetries we determine the polarised quark distributions of valence quarks and non-strange sea quarks at =10 GeV. The polarised valence quark distribution, , is positive and the polarisation increases with . The polarised valence quark distribution, , is negative and the non-strange sea distribution, , is consistent with zero over the measured range of . We find for the first moments , and , where we assumed . We also determine for the first time the second moments of the valence distributions .We present a measurement of semi-inclusive spin asymmetries for positively and negatively charged hadrons from deep inelastic scattering of polarised muons on polarised protons and deuterons in the range 1 GeV. Compared to our previous publication on this subject, with the new data the statistical errors have been reduced by nearly a factor of two. From these asymmetries and our inclusive spin asymmetries we determine the polarised quark distributions of valence quarks and non-strange sea quarks at =10 GeV. The polarised valence quark distribution, , is positive and the polarisation increases with . The polarised valence quark distribution, , is negative and the non-strange sea distribution, , is consistent with zero over the measured range of . We find for the first moments , and , where we assumed . We also determine for the first time the second moments of the valence distributions .We present a measurement of semi-inclusive spin asymmetries for positively and negatively charged hadrons from deep inelastic scattering of polarised muons on polarised protons and deuterons in the range 1 GeV. Compared to our previous publication on this subject, with the new data the statistical errors have been reduced by nearly a factor of two. From these asymmetries and our inclusive spin asymmetries we determine the polarised quark distributions of valence quarks and non-strange sea quarks at =10 GeV. The polarised valence quark distribution, , is positive and the polarisation increases with . The polarised valence quark distribution, , is negative and the non-strange sea distribution, , is consistent with zero over the measured range of . We find for the first moments , and , where we assumed . We also determine for the first time the second moments of the valence distributions .We present a measurement of semi-inclusive spin asymmetries for positively and negatively charged hadrons from deep inelastic scattering of polarised muons on polarised protons and deuterons in the range 1 GeV. Compared to our previous publication on this subject, with the new data the statistical errors have been reduced by nearly a factor of two. From these asymmetries and our inclusive spin asymmetries we determine the polarised quark distributions of valence quarks and non-strange sea quarks at =10 GeV. The polarised valence quark distribution, , is positive and the polarisation increases with . The polarised valence quark distribution, , is negative and the non-strange sea distribution, , is consistent with zero over the measured range of . We find for the first moments , and , where we assumed . We also determine for the first time the second moments of the valence distributions .We present a measurement of semi-inclusive spin asymmetries for positively and negatively charged hadrons from deep inelastic scattering of polarised muons on polarised protons and deuterons in the range 0.0031 GeV 2 . Compared to our previous publication on this subject, with the new data the statistical errors have been reduced by nearly a factor of two. From these asymmetries and our inclusive spin asymmetries we determine the polarised quark distributions of valence quarks and non-strange sea quarks at Q 2 =10 GeV 2 . The polarised u valence quark distribution, Îu v ( x ), is positive and the polarisation increases with x . The polarised d valence quark distribution, Îd v ( x ), is negative and the non-strange sea distribution, Î q Ì (x) , is consistent with zero over the measured range of x . We find for the first moments â« 0 1 Îu v (x) d x=0.77±0.10±0.08 , â« 0 1 Îd v (x) d x=â0.52±0.14±0.09 and â« 0 1 Î q Ì (x) d x=0.01±0.04±0.03 , where we assumed Î u Ì (x)=Î d Ì (x) . We also determine for the first time the second moments of the valence distributions â« 0 1 xÎq v (x) d x
Sedimentation and Fouling of Optical Surfaces at the ANTARES Site
ANTARES is a project leading towards the construction and deployment of a
neutrino telescope in the deep Mediterranean Sea. The telescope will use an
array of photomultiplier tubes to detect the Cherenkov light emitted by muons
resulting from the interaction with matter of high energy neutrinos. In the
vicinity of the deployment site the ANTARES collaboration has performed a
series of in-situ measurements to study the change in light transmission
through glass surfaces during immersions of several months. The average loss of
light transmission is estimated to be only ~2% at the equator of a glass sphere
one year after deployment. It decreases with increasing zenith angle, and tends
to saturate with time. The transmission loss, therefore, is expected to remain
small for the several year lifetime of the ANTARES detector whose optical
modules are oriented downwards. The measurements were complemented by the
analysis of the ^{210}Pb activity profile in sediment cores and the study of
biofouling on glass plates. Despite a significant sedimentation rate at the
site, in the 0.02 - 0.05 cm.yr^{-1} range, the sediments adhere loosely to the
glass surfaces and can be washed off by water currents. Further, fouling by
deposits of light-absorbing particulates is only significant for surfaces
facing upwards.Comment: 18 pages, 14 figures (pdf), submitted to Astroparticle Physic
ANTARES: the first undersea neutrino telescope
The ANTARES Neutrino Telescope was completed in May 2008 and is the first
operational Neutrino Telescope in the Mediterranean Sea. The main purpose of
the detector is to perform neutrino astronomy and the apparatus also offers
facilities for marine and Earth sciences. This paper describes the design, the
construction and the installation of the telescope in the deep sea, offshore
from Toulon in France. An illustration of the detector performance is given
An overview of Mike Moravcsik's publication activity in physics
Todorov R, Winterhager M. An overview of Mike Moravcsik's publication activity in physics. Scientometrics. 1991;20(1):163-172.A bibliometric online technique is applied on data from the INSPEC bibliographic file to describe some aspects of Moravcsik's publication activity (co-authorship, source journals, etc.). Separately, a co-occurrence method is used to represent the subject structure (the main topics and their links) of his papers in physics. The principle underlying this method is to develop a network based on common appearances of classification subdivisions (headings) as well as of controlled terms in Moravcsik's document records. The results, in the form of line and point graphs, give a global picture of Mike Moravcsik's research profile in physics