Integral cross sections for the scattering of pions by protons into angles greater than 30 degrees (lab) have been measured at a wide range of energies spanning the delta resonance using liquid hydrogen targets. Cross sections were measured for nip scattering at 40 energies from 39.8 to 283.9 MeV and for pi(-)p at 15 energies from 80.0 to 283.9 MeV. Comparisons with phase shift predictions from the Karlsruhe group show good agreement on resonance but significant deviations below 100 MeV. [S0556-2813(99)02903-9].

Measurements were made at SLAC of the cross section for scattering 29 GeV electrons from carbon at a laboratory angle of 4.5 degrees, corresponding to 0.03<x<0.1 and 1.3<Q^2<2.7 GeV^2. Values of R=sigma_L/sigma_T were extracted in this kinematic range by comparing these data to cross sections measured at a higher beam energy by the NMC collaboration. The results are in reasonable agreement with pQCD calculations and with extrapolations of the R1990 parameterization of previous data. A new fit is made including these data and other recent results.

Ratios of double-differential cross sections for incident 500-MeV pions are presented for (π+,π+p) and (π+,π−p) reactions on 12,13C, 90Zr, and 208Pb. A comparison with intra-nuclear cascade-model calculations suggest that the outgoing pion spectra show a feature consistent with quasi-free scattering from the Δ− component of the nuclear ground state wave function.

The RSS collaboration has measured the spin structure functions of the proton and the deuteron at Jefferson Lab using the Hall C HMS spectrometer, a polarized electron beam and a polarized solid target. The asymmetries A∥ and A⊥ were measured in the region of the nucleon resonances (0.82 GeV < W < 1.98 GeV) at an average four momentum transfer of Q2 = 1.3 GeV2. The extracted spin structure functions and their kinematic dependence will make a significant contribution in the study of higher‐twist effects and polarized duality tests. A description of the experiment and the latest findings of the analysis will be presented.

Reaction and total cross sections for ${\mathrm{\ensuremath{\pi}}}^{+}$ and ${\mathrm{\ensuremath{\pi}}}^{\mathrm{\ensuremath{-}}}$ on targets of $^{2}\mathrm{H}$, $^{6}\mathrm{Li}$, C, Al, Si, S, and Ca have been measured for beam energies from 42 to 65 MeV. The cross sections are proportional to the target mass at 50 MeV, consistent with transparency to these projectiles. The cross sections are compared to theoretical calculations. \textcopyright{} 1996 The American Physical Society.

(E143 1 Collaboration) o TheAmericanUniversity,Washington,D.C. 20016 » Institut 1⁄4 für Physikder Universität Basel,CH 4056Basel,Switzerland 1⁄2 Laboratoire 3⁄4 de PhysiqueCorpusculaire,IN2P3/CNRS,UniversityBlaisePascal,F-63170AubiereCedex,France ¿ Continuous À ElectronBeamAcceleratorFacility, NewportNews,Virginia 23606 Á DAPNIA-Servicede PhysiqueNucleaireCentred’Etudesde Saclay,91191Gif-sur-Yvette,France  Lawrence 3⁄4 LivermoreNational Laboratory,Livermore,California 94550 à Universityyof Massachusetts, Amherst,Massachusetts 01003 Ä Universityof Michigan,Ann Arbor, Michigan 48109 Å Naval Æ PostgraduateSchool,Monterey,California 93943 Ç È Old DominionUniversity,Norfolk, Virginia 23529 ÉÊÉ Universityof Pennsylvania,Philadelphia,Pennsylvania19104 Ë Ì StanfordLinear AcceleratorCenter,Stanford,California 94309 Í Î StanfordUniversity,Stanford,California 94305 Ï Ð Temple Ñ University,Philadelphia,Pennsylvania19122 Ò Ó TohokuUniversity,Sendai980,Japan Ô Õ Universityof Virginia, Charlottesville,Virginia 22901 Ö × Universityof Wisconsin,Madison,Wisconsin53706 ( 1 Received8 March1995) Ø

Differential cross sections from 3He(π±, π0) and 3He(π±, π0p) measurements are presented. The π0 energy spectra from 3He(π±, π0) and 3He(π+, π0p) are characteristic of quasi-free reactions. The proton angular distribution from 3He(π+, π0p) also show evidence of a quasi-free mechanism. Indications of multi-nucleon processes are presented in the 3He(π−, π0p) data. At least two nucleons must be involved. Comparisons between coincidence and single-arm measurements from this work and previous measurements of charged pion scattering on 3He provide evidence of an enhanced multiple scattering contribution to the charge exchange channel.

Absolute ${\mathrm{\ensuremath{\pi}}}^{\ifmmode\pm\else\textpm\fi{}}$p elastic scattering differential cross sections have been measured at five incident pion energies between 87 and 139 MeV. An active target of scintillator material (${\mathit{CH}}_{1.1}$) was used to detect recoil protons in coincidence with scattered pions. Pions were detected at forward angles between 27 and 98${\mathrm{\ifmmode^\circ\else\textdegree\fi{}}}_{\mathrm{c}.\mathrm{m}.}$ where the low-energy recoil protons stop in the target. The cross sections, typically 5--10% lower than phase shift predictions for ${\mathrm{\ensuremath{\pi}}}^{+}$p and 10--20% lower for the ${\mathrm{\ensuremath{\pi}}}^{\mathrm{\ensuremath{-}}}$p cross sections, are consistent with earlier measurements by this group.

The ratio g1F1 has been measured over the range 0.03 < x < 0.6 and 0.3 < Q2 < 10 (GeV/c)2 using deep-inelastic scattering of polarized electrons from polarized protons and deuterons. We find g1F1 to be consistent with no Q2-dependence at fixed x in the deep-inelastic region Q2 > 1 (GeV/c)2. A trend is observed for g1F1 to decrease at lower Q2. Fits to world data with and without a possible Q2-dependence in g1F1 are in agreement with the Bjorken sum rule, but Δq is substantially less than the quark-parton model expectation.

The design of a coincident sampling grid scintillator (SGS) is described, with applications to particle identification in intense secondary beams. Timing resolution of 1 ns is able to distinguish pions from electrons, and pulse heights are able to resolve pions from muons at low momentum. Pulse height resolution is also used to distinguish π+ from protons at high momentum, and this is used to understand the LAMPF P3 channel particle separation.

The tensor polarization of the recoil deuteron in elastic electron-deuteron scattering has been measured at the Bates Linear Accelerator Center at three values of four-momentum transfer, Q = 3.78, 4.22, and 4.62 fm-1, corresponding to incident electron energies of 653, 755, and 853 MeV. The scattered electrons and the recoil deuterons were detected in coincidence. The recoil deuterons were transported to a liquid hydrogen target to undergo a second scattering. The angular distribution of the d-p scattering was measured using a polarimeter. The polarimeter was calibrated in an auxiliary experiment using a polarized deuteron beam at the Laboratoire National Saturne. A Monte Carlo procedure was used to generate interpolated calibration data because the energy spread in the deuteron energies in the Bates experiment spanned the range of deuteron energies in the calibration experiment. The extracted Values of t20 are compared to predictions of different theoretical models of the electromagnetic form factors of the deuteron: nonrelativistic and relativistic nucleon-meson dynamics, Skyrme model, quark models, and perturbative quantum chromodynamics. Along with the world data on the structure functions A(Q) and B(Q), they are used to separate the charge monopole and charge quadrupole form factors of the deuteron. A node in the charge monopole form factor is observed at Q = 4.39 +/- 0.16 fm-1.

The isovector nuclear response of carbon is calculated using a random-phase approximation technique for both the non-spin-flip and the spin-flip channel. The calculated results are found to be in fair agreement with experimental results from C(${\mathrm{\ensuremath{\pi}}}^{\mathrm{\ensuremath{-}}}$,${\mathrm{\ensuremath{\pi}}}^{0}$) measurements at 500 and 400 MeV. The nuclear correlations quench and harden the charge-exchange quasifree peak as predicted.