[en] Hypernuclear physics is expected to play a large part in the TJNAF physics program. Several experiments in Halls A and C[1,2,4] have been approved to measure properties of bound hyperons. These experiments focus on measurements of the ΛN potential. The goal is to extract enough information to constrain the potential. The ΛN potential can be written as: V_#Lambda#_N = V(r) + V_N(r)s_N · 1_#Lambda#_N + V_#Lambda#(r)s_#Lambda# · 1_#Lambda#_N + V_σ(r)s_#Lambda# · s_N + V_T(r)S₁₂ where V(r) is the central part of the potential, V_N(r)s_N · 1_#Lambda#_N is the spin-orbit part of the nucleon-hyperon and V_#Lambda#(r)s_#Lambda# · 1_#Lambda#_N is the spin-orbit part of the hyperon-nucleon interactions, V_σ(r)s_#Lambda# · s_N is the spin-spin part of the potential and V_T(r)S₁₂ is the tensor part of the interaction

[en] The reaction p(e,e(prime)pi⁺)X⁰ was studied with two high resolution magnetic spectrometers to search for narrow baryon resonances. A missing mass resolution of 2.0 MeV was achieved. A search for structures in the mass region of 0.97 < M_X#sup 0# < 1.06 GeV yielded no significant signal. The yield ratio of p(e,e(prime)pi⁺)X⁰/p(e,e(prime)pi⁺)n was determined to be (-0.35 ± 0.35) times 10^-3 at 1.004 GeV and (0.34 ± 0.42) times 10^-3 at 1.044 GeV

[en] Results are presented from a new experiment (E94-107) in Hall A of the Thomas Jefferson National Accelerator Facility (JLab) producing Boron-12-lambda using electroproduction, (e,e(prime)K+). In the hypernuclear missing-mass spectrum the experiment achieves very good energy resolution (640 keV FWHM) by exploiting the characteristics of the High Resolution spectrometer pair and the exceptional beam quality available at JLab. The spectrometers were used with the addition an INFN provided pair of septum magnets to reach the desired small angles. Also, the Hall A standard complement of equipment was further augmented by the addition of a Ring Imaging Cherenkov detector (RICH) to achieve the best possible kaon identification

[en] Results are presented from a new experiment (E94-107) in Hall A of the Thomas Jefferson National Accelerator Facility (JLab) producing 12Λ B, 16ΛN, and 9ΛLi using electroproduction, (e,e(prime)K+). In the hypernuclear missing-mass spectrum the experiment achieves very good energy resolution (670 keV FWHM) by exploiting the characteristics of the High Resolution spectrometer pair and the exceptional beam quality available at JLab. The spectrometers were used with the addition an INFN provided pair of septum magnets to reach the desired small angles. Also, the Hall A standard complement of equipment was further augmented by the addition of a Ring Imaging Cherenkov detector (RICH) to achieve the best possible kaon identification

[en] We propose to measure pion electroproduction off ¹H, ², ¹²C, ⁶⁴Cu, and ¹⁹⁷Au, and extract the pion transparency through the nuclear medium between Q² = 1 and 5 (GeV/c)². The pion transparency is predicted to be a signature of the onset of nuclear filtering and/or Color Transparency. Recent experiments have reported evidence for Color Transparency effects at Q² approx 10 (GeV/c)². The occurrence of nuclear filtering could potentially explain the apparent discrepancy between (proton) nuclear transparencies found in quasielastic A(e,e'p) and A(p,2p) experiments. The occurrence of these effects is an effective signature of the approach to the factorization regime in meson electroproduction experiments, necessary for the access to Generalized Parton Distributions. Measurable effects of approx. 40% are predicted for this region of Q². The proposed experiment seeks to measure the pion transparency with 5-10% uncertainties, dominated by systematics, up to Q² = 5 (GeV/c)²

[en] The first ''systematic'' study of 1 p shell hypernuclei with electromagnetic probes has started in Hall A at Jefferson Lab [?]. The aim is to perform hypernuclear high resolution spectroscopy by the electroproduction of strangeness on four 1p-shell targets: 12C, 9Be, 16O, 7Li. The first part of the experiment on 12C and 9Be has been performed in 2004, the second part (16O and 7Li) is scheduled for June 2005. To overcome the major experimental difficulties, namely the low counting rate and the challenging Particle IDentification (PID), two septum magnets and a Ring Imaging CHerenkov (RICH) detector had to be added to the existing apparatus. After underlining the particular role the electroproduction reaction plays in hypernuclear physics we describe the challenging modifications of the Hall A apparatus. Preliminary results on 12C and 9Be are presented

[en] Since 2004 the hadron spectrometer of Hall A at Jefferson Lab is equipped with a proximity focusing RICH. This detector is capable of identify kaon from pion and proton with an angular separation starting from 6 sigma at 2 GeV/c. The RICH design is conceptually similar to the ALICE HMPID RICH; it uses a C6F14 liquid radiator and a 300 nm layer of CsI deposited on the cathode pad plane of an asymmetric MWPC. The RICH has operated for the Hypernuclear Spectroscopy Experiment E94-107, which took data in the last two years. Design details and performance along with first physics results from the hypernuclear experiment are shortly presented

[en] We report a measurement of the neutron detection efficiency for an array of neutron detectors behind a lead-steel wall consisting of 10.16 cm thick lead bricks sandwiched between 3.18 cm steel plates. The neutron detection efficiency was obtained from the ratio of coincidence to single-arm proton cross sections using the gamma+²₁H -->p+n reaction. Knowledge of the neutron detection efficiency was necessary to extract the cross section for the exclusive ²H(e,e'n)¹H reaction, which we used to obtain the elastic magnetic form factor Gⁿ_M of the neutron. The measurements for three different neutron energies were carried out at the MIT-Bates Linear Accelerator Center with an incident electron beam energy of 254 MeV

[en] We determined the electric form factor GnE of the neutron from the quasielastic 2H(e-->,e'n-->)1H reaction at a central squared four-momentum transfer Q2=0.255 (GeV/c)2 with a longitudinally polarized electron beam of 868 MeV and a low (∼0.8%) duty factor. A neutron polarimeter designed and constructed specifically for this experiment was used to measure the sideways polarization of the recoil neutron, which was detected in coincidence with the scattered electron. Theoretical calculations have established that this polarization-transfer technique for quasielastic scattering produces a value of GnE that shows little sensitivity to the influence of final-state interactions, meson-exchange currents, isobar configurations, and deuteron structure. The value for GnE from this measurement is 0.066 ± 0.036 ± 0.009

[en] The A(Q²) structure function in elastic electron-deuteron scattering was measured at six momentum transfers Q² between 0.66 and 1.80 (GeV/c)² in Hall C at Jefferson Laboratory. The scattered electrons and recoil deuterons were detected in coincidence, at a fixed deuteron angle of 60.5^o. These new precise measurements resolve discrepancies between older sets of data. They put significant constraints on existing models of the deuteron electromagnetic structure, and on the strength of isoscalar meson exchange currents