High-energy physics experiments, such as the compact muon solenoid (CMS) at the large hadron collider (LHC), have large-scale data processing computing requirements. The grid has been chosen as the ...solution. One important challenge when using the grid for large-scale data processing is the ability to monitor the large numbers of jobs that are being executed simultaneously at multiple remote sites. The relational grid monitoring architecture (R-GMA) is a monitoring and information management service for distributed resources based on the GMA of the Global Grid Forum. We report on the first measurements of R-GMA as part of a monitoring architecture to be used for batch submission of multiple Monte Carlo simulation jobs running on a CMS-specific LHC computing grid test bed. Monitoring information was transferred in real time from remote execution nodes back to the submitting host and stored in a database. In scalability tests, the job submission rates supported by successive releases of R-GMA improved significantly, approaching that expected in full-scale production.
A measurement of the proton spin structure function g1p(x,Q{sup 2}) in deep-inelastic scattering is presented. The data were taken with the 27.6 GeV longitudinally polarised positron beam at HERA ...incident on a longitudinally polarised pure hydrogen gas target internal to the storage ring. The kinematic range is 0.021<x<0.85 and 0.8 GeV{sup 2}<Q{sup 2}<20 GeV{sup 2}.
Measurements of the individual multiplicities of \(\pi^+, \pi^-\) and \(\pi^0\) produced in the deep-inelastic scattering of 27.5 GeV positrons on hydrogen are presented. The average charged pion ...multiplicity is the same as for neutral pions, up to \(z \approx 0.7\), where z is the fraction of the energy transferred in the scattering process carried by the pion. This result (below \(z \approx 0.7\)) is consistent with isospin invariance. The total energy fraction associated with charged and neutral pions is \(\rm 0.51 \pm 0.01 (stat.) \pm 0.08\) (syst.) and \(\rm 0.26 \pm 0.01 (stat.) \pm 0.04 (syst.)\), respectively. For fixed z, the measured multiplicities depend on both the negative squared four momentum transfer \(Q^2\) and the Bjorken variable x. The observed dependence on \(Q^2\) agrees qualitatively with the expected behaviour based on NLO-QCD evolution, while the dependence on x is consistent with that of previous data after corrections have been made for the expected \(Q^2\)-dependence.
The dependence on Q{sup 2} (the negative square of the 4-momentum of the exchanged virtual photon) of the generalised Gerasimov-Drell-Hearn integral for the proton has been measured in the range 1.2 ...GeV{sup 2}<Q{sup 2}<12 GeV{sup 2} by scattering longitudinally polarised positrons on a longitudinally polarised hydrogen gas target. The contributions of the nucleon-resonance and deep inelastic regions to this integral have been evaluated separately. The latter has been found to dominate for Q{sup 2}>3 GeV{sup 2}, while both contributions are important at low Q{sup 2}. The total integral shows no significant deviation from a 1/Q{sup 2} behavior in the measured Q{sup 2} range, and thus no sign of large effects due to either nucleon-resonance excitations or nonleading twist.
The dependence on
Q
2 (the negative square of the 4-momentum of the exchanged virtual photon) of the generalised Gerasimov–Drell–Hearn integral for the proton has been measured in the range 1.2 GeV
...2<
Q
2<12 GeV
2 by scattering longitudinally polarised positrons on a longitudinally polarised hydrogen gas target. The contributions of the nucleon-resonance and deep inelastic regions to this integral have been evaluated separately. The latter has been found to dominate for
Q
2>3 GeV
2, while both contributions are important at low
Q
2. The total integral shows no significant deviation from a 1/
Q
2 behaviour in the measured
Q
2 range, and thus no sign of large effects due to either nucleon-resonance excitations or nonleading twist.
The HERMES polarized 3He internal gas target DeSchepper, D.; Kramer, L.H.; Pate, S.F. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/1998, Letnik:
419, Številka:
1
Journal Article
Recenzirano
The HERMES experiment is investigating the spin structure of the proton and neutron
via deep-inelastic scattering of polarized positrons from polarized nuclear targets. The polarized positrons are ...provided by the HERA positron storage ring at DESY, Hamburg, Germany. The targets are pure internal gas targets. Data acquisition began in 1995, utilizing a polarized
3He internal gas target to study the spin structure of the neutron. The target gas was polarized using the metastability-exchange optical-pumping technique and then injected into a cryogenically cooled target cell. The target was designed to operate with either longitudinal or transverse directions of polarization. Operating conditions included polarizations of up to 54% and target thicknesses of 1×10
15 nucleons/cm
2. In this paper the HERMES polarized
3He internal gas target is described in detail.
A measurement of the proton spin structure function
g
1
p(
x,
Q
2) in deep-inelastic scattering is presented. The data were taken with the 27.6 GeV longitudinally polarised positron beam at HERA ...incident on a longitudinally polarised pure hydrogen gas target internal to the storage ring. The kinematic range is 0.021<
x<0.85 and 0.8 GeV
2<
Q
2<20 GeV
2. The integral
∫
0.021
0.85
g
1
p
(x)
dx
evaluated at
Q
0
2 of 2.5 GeV
2 is 0.122±0.003(stat.)±0.010(syst.).
Results are reported from the HERMES experiment at HERA on a measurement of the neutron spin structure function
g
1
n
(
x, Q
2) in deep inelastic scattering using 27.5 GeV longitudinally polarized ...positrons incident on a polarized
3He internal gas target. The data cover the kinematic range 0.023 < × < 0.6 and 1 (GeV/
c)
2 <
Q
2 < 15 (GeV/
c)
2. The integral ∫
0.6
0.023
g
1
n
(
x)
dx evaluated at a fixed
Q
2 of 2.5 (GeV/
c)
2 is −0.034 ± 0.013(stat.)±0.005(syst.). Assuming Regge behavior at low
x, the first moment Г
n
1 = ∫
1
0
g
1
n
(
x)
dx is −0.037 ± 0.013(stat.)±0.005(syst.)±0.006(extrapol.).
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