The (e, e 0 p) reaction was studied on targets of C, Fe, and Au at momentum transfers squared Q 2 of 0.6, 1.3, 1.8, and 3.3 GeV 2 in a region of kinematics dominated by quasifree electron-proton scattering. Missing energy and missing momentum distributions are reasonably well described by plane wave impulse approximation calculations with Q 2 and A dependent corrections that measure the attenuation of the final state protons. [S0031-9007 (98) The (e, e 0 p) reaction with nearly free electron-proton kinematics (quasifree) has proven to be a valuable tool to study the propagation of nucleons in the nuclear medium [1][2][3]. The relatively weak interaction of the electron with the nucleus allows the electrons to penetrate the nuclear interior and knock out protons. These studies complement nucleon-induced measurements of proton propagation in nuclei which give more emphasis to the nuclear surface. This paper reports the first results of a systematic study of the quasifree knockout of protons of 300-1800 MeV kinetic energy from carbon, iron, and gold targets. This energy range includes the minimum of the nucleon-nucleon (N-N) total cross section, the rapid rise in this cross section with energy above the pion production threshold, and extends to the long plateau in the energy dependence of the N-N total cross section. These features of the N-N interaction would be expected to be reflected in the energy dependence of attenuation of protons as they pass 5072 0031-9007͞98͞80(23)͞5072(5)$15.00

We report a measurement of the asymmetry in spin-dependent quasielastic scattering of longitudinally polarized electrons from a polarized 3~e target. The neutron magnetic form factor G' ;, has been extracted from the measured asymmetry based on recent PWIA calculations using spin-dependent spectral functions. Our determination of G& at ~~= 0 . 1 9 (G~VIC)' agrees with the dipole parametrization. This experiment represents the first measurement of the neutron magnetic form factor using spin-dependent electron scattering. PACS nuniber(s): 25.30. Fj, 13.40.Gp, 14.20.Dh, 24.70.fs Electromagnetic form factors are of fundamental importance for an understanding of the underlying structure of nucleons. Knowledge of the distribution of charge and magnetization within the nucleons provides a sensitive test of models based on QCD, as well as a basis for calculations of processes involving the electromagnetic interaction with complex nuclei. Due to the lack of a free neutron target, the neutron electromagnetic form factors are known with less precision than the proton electric and magnetic form factors. They have been deduced in the past from elastic or quasielastic electron-deuteron scattering. This procedure involves considerable model dependence. The development of polarized targets and beams has allowed more complete studies of electromagnetic structure than has been possible with unpolarized reactions. In quasielastic scattering, the spin degrees of freedom introduce new response functions into the inclusive cross section, thus providing additional information on nuclear structure [I].3~e is an interesting nucleus for polarization studies because its ground state wave function is predominantly a spa- tially symmetric S state in which the spin of the nucleus is carried mainly by the unpaired neutron. Therefore, inelastic scattering of polarized electrons from polarized '~e in the vicinity of the quasielastic peak should be useful for studying the neutron electromagnetic form factors. This idea was first investigated by Blankleider and Woloshyn in closure approximation [2]. Friar et al. [3] have studied the model dependence in the spin structure of the 3~e wave function and its effect on the quasielastic asymmetry. Recently the plane wave impulse approximation (PWIA) calculations performed independently by two groups [4,5] using a spin-dependent spectral function show that the spin-dependent asymmetry is very sensitive to the neutron electric or magnetic form factors at certain kinematics near the top of the quasielastic peak. Two previous experiments [6,7] measured the spindependent asymmetry in quasielastic scattering of polarized electrons from oolarized h e . and demonstrated that this new experimental technique is feasible for studying the neutron electromagnetic structure. As a result, new experimental programs utilizing polarized electrons and polarized %e targets to study the neutron electromagnetic structure and the nucleon spin structure are under way at several electron accelerator laboratories (SLAC, MIT-B...

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Friedel-Crafts acylation has been known since the 1870s and it is an important organic synthetic reaction leading to aromatic ketone products. Friedel-Crafts acylation is usually done with carboxylic acid chlorides or anhydrides while amides are generally not useful substrates in these reactions. Despite being the least reactive carboxylic acid derivative, we have found a series of amides capable of providing aromatic ketones in good yields (55–96%, 17 examples). We propose a mechanism involving diminished C-N resonance through superelectrophilic activation and subsequent cleavage to acyl cations.

Experimental and theoretical studies suggest the involvement of dicationic, superelectrophilic N-acyliminium ions in conversions catalyzed by superacids.

A separation of the longitudinal and transverse 12 C(e,eЈp) cross sections in the quasifree region has been performed in parallel kinematics at Q 2 of 0.64 and 1.8 GeV 2 for initial proton momentum Ͻ80 MeV. The separated transverse and longitudinal spectral functions at Q 2 ϭ0.64 GeV 2 show significant differences for missing energy between 25 and 60 MeV indicating a breakdown in the single nucleon knockout picture. The transverse spectral functions exhibit definite momentum transfer dependence.PACS number͑s͒: 25.30.Fj, 25.30.Rw

The transverse-longitudinal asymmetry A&« in 'He(e, e') quasielastic scattering at momentum transfer Q' = 0.14(GeV/c)2 has been measured to be 1.52~0.55(stat)~0.15(syst)%. The plane wave impulse approximation (PWIA) prediction for this measurement ranges from 2.1% to 2.9%, where the variation is due to uncertainty in the initial state wave function, nucleon form factors, and off-shell prescription. The data may suggest a suppression with respect to the PWIA, which has also been observed for the unpolarized longitudinal response function.