The influence of cold nuclear matter on lepto-production of hadrons in semi-inclusive deep inelastic scattering is measured using the CLAS detector in Hall B at Jefferson Lab and a 5.014 GeV electron ...beam. We report the $K_s^0$ multiplicity ratios for targets of C, Fe, and Pb relative to deuterium as a function of the fractional virtual photon energy $z$ transferred to the $K_s^0$ and the transverse momentum squared $p_{T}^2$ of the $K_s^0$. We find that the multiplicity ratios for $K^0_s$ are reduced in the nuclear medium at high $z$ and low $p_{T}^2$, with a trend for the $K^0_s$ transverse momentum to be broadened in the nucleus for large $p_{T}^2$.
Cross section ratios for deep-inelastic scattering from
14N and
3He with respect to
2H have been measured by the HERMES experiment at DESY using a 27.5 GeV positron beam. The data cover a range in ...the Bjorken scaling variable
x between 0.013 and 0.65, while the negative squared four-momentum transfer
Q
2 varies from 0.5 to 15 GeV
2. The data are compared to measurements performed by NMC, E665, and SLAC on
4He and
12C, and are found to be different for
x<0.06 and
Q
2<1.5 GeV
2. The observed difference is attributed to an
A-dependence of the ratio
R=
σ
L
/
σ
T
of longitudinal to transverse deep-inelastic scattering cross sections at low
x and low
Q
2.
Performance of F101 radiation resistant lead glass shower counters Avakian, H.; Bianchi, N.; Capitani, G.P. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
08/1996, Letnik:
378, Številka:
1
Journal Article
Recenzirano
The performance of F101 lead glass as a Cherenkov radiation material was studied. A 3 × 3 array of 9 × 9 cm
2 and 50 cm length counters showed an energy resolution of
≈5.0%
E(GeV)
, good linearity in ...the energy range from 1 to 25 GeV and
π
−
e
rejection of ≈4 × 10
−4.
The Gerasimov-Drell-Hearn (GDH) sum rule connects the anomalous contribution to the magnetic moment of the target nucleus with an energy-weighted integral of the difference of the helicity-dependent ...photoabsorption cross sections. Originally conceived for real photons, the GDH integral can be generalised to the case of photons with virtuality Q2. For spin-1/2 targets such as the nucleon, it then represents the non-perturbative limit of the first moment \(\Gamma_1\) of the spin structure function g1(x,Q2) in deep inelastic scattering (DIS). The data collected by HERMES with a deuterium target are presented together with a re-analysis of previous measurements on the proton. This provides an unprecedented and complete measurement of the generalised GDH integral for photon-virtuality ranging over 1.2<Q2<12.0 GeV2 and for photon-nucleon invariant mass squared W2 ranging over 1<W2<45 GeV2, thus covering simultaneously the nucleon-resonance and the deep inelastic scattering regions. These data allow the study of the Q2-dependence of the full GDH integral, which is sensitive to both the Q2-evolution of the resonance form factors and contributions of higher twist. The contribution of the nucleon-resonance region is seen to decrease rapidly with increasing Q2. The DIS contribution is sizeable over the full measured range, even down to the lowest measured Q2. As expected, at higher Q2 the data are found to be in agreement with previous measurements of the first moment of g1. From data on the deuteron and proton, the GDH integral for the neutron has been derived and the proton-neutron difference evaluated. This difference is found to satisfy the fundamental Bjorken sum rule at Q2 = 5 GeV2.
A single-spin asymmetry in the distribution of exclusively produced
π
+ mesons azimuthally around the virtual photon direction relative to the lepton scattering plane has been measured for the first ...time in deep-inelastic scattering of positrons off longitudinally polarized protons. Integrated over the experimental acceptance, the sin
φ moment of the polarization asymmetry of the cross section is measured to be −0.18±0.05(stat.)±0.02(syst.). The asymmetry is also studied as a function of the relevant kinematic variables, and its magnitude is found to grow with decreasing
x and increasing −
t and vanish at
t→
t
min (where
x is the Bjorken scaling variable and
t is the squared four-momentum transferred to the nucleon).
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.
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