0000000000275301
AUTHOR
B. Roscherr
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 $0.003$1 GeV$^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, $\Delta u_v(x)$, is positive and the polarisation increases with $x$. The polarised $d$ valence quark distribution, $\De…
A large Streamer Chamber muon tracking detector in a high-flux fixed-target application.
Arrays of limited streamer tubes of the Iarocci type were deployed in our experiment at CERN as part of a forward muon detector system with provisions for the beam to pass through the center of each panel in the array. A total of 16 4 m x 4 m panels were assembled with inductive readout strips on both sides of each panel. An active feedback system. was deployed to regulate the high voltage to the streamer tubes to insure a constant efficiency for minimum ionizing particles. The arrays were operated in this environment for over five years of data taking. Streamer tube track-reconstruction efficiencies and tube replacement rates are reported. (C) 1999 Elsevier Science B.V. All rights reserved.
The spin-dependent structure function g1(x) of the proton from polarized deep-inelastic muon scattering
We present a new measurement of the virtual photon proton asymmetry $A_1^{\rm p}$ from deep inelastic scattering of polarized muons on polarized protons in the kinematic range $0.0008 1$ GeV$^{2}$. A perturbative QCD evolution in next-to-leading order is used to determine $g_1^{\rm p}(x)$ at a constant $Q^2$. At $Q^{2} = 10$ GeV$^{2}$ we find, in the measured range, $\int_{0.003}^{0.7} g_{1}^{\rm p}(x){\rm d}x = 0.139 \pm 0.006~({\rm stat})\pm 0.008~({\rm syst)} \pm 0.006~({\rm evol})$. The value of the first moment $\Gamma_{1}^{\rm p} = \int_{0}^{1} g_{1}^{\rm p}(x){\rm d}x$ of $g_{1}^{\rm p}$ depends on the approach used to describe the behaviour of $g_{1}^{\rm p}$ at low $x$. We find tha…
The polarized double cell target of the SMC
The polarized target of the Spin Muon Collaboration at CERN was used for deep inelastic muon scattering experiments during 1993-1996 with a polarized muon beam to investigate the spin structure of the nucleon. Most of the experiments were carried out with longitudinal target polarization and 190 GeV muons, and some were done with transverse polarization and 100 GeV muons. Protons as well as deuterons were polarized by dynamic nuclear polarization (DNP) in three kinds of solid materials - butanol, ammonia, and deuterated butanol - with maximum degrees of polarization of 94%, 91% and 60%, respectively. Considerable attention was paid to the accuracies of the NMR polarization measurements and …