The electromagnetic polarizabilities of the nucleon are fundamental properties that describe its response to external electric and magnetic fields. They can be extracted from Compton-scattering data --- and have been, with good accuracy, in the case
of the proton. In contradistinction, information for the neutron requires the use of Compton scattering from nuclear targets. Here we report a new measurement of elastic photon scattering from deuterium using quasimonoenergetic tagged photons at the MAX IV Laboratory in Lund, Sweden. These first new data in more than a decade effectively double the world dataset. Their energy range overlaps with previous experiments and extends it by 20 MeV to higher energies. An analysis using Chiral Effective Field Theory with dynamical Delta(1232) degrees of freedom shows the data are consistent with and within the world dataset. After demonstrating that the fit is consistent with the Baldin sum rule, extracting values for the isoscalar nucleon polarizabilities and combining them with a recent result for the proton, we obtain the neutron polarizabilities as alpha_n = [11.55 +/- 1.25(stat) +/- 0.2(BSR) +/- 0.8(th)] X 10^{-4} fm^3 and beta_n = [3.65 -/+ 1.25(stat) +/- 0.2(BSR) -/+ 0.8(th)] X 10^{-4} fm3, with chi^2 = 45.2 for 44 degrees of freedom.
E12-14-009: We propose to extract the ratio of the electric form factor (G_E) of 3He and 3H from the measured ratio of the elastic-scattering cross sections at E_beam = 1.1 GeV. Measurements at low Q^2 ( < 0.1 GeV^2) will allow accurate extraction of
G_E with minimal contributions from the magnetic form factor (G_M) and Coulomb corrections. From this data we will extract the difference between the charge radii for 3He and 3H. This short experiment, 1.5 days, will utilize the left Hall A high resolution spectrometer and the one-time availability of a 1 kCi tritium target at Jefferson Lab which has been approved for the E12-10-103, E12-11-112 and E12-14-011 experiments.
Cross sections for uc{6}{Li}($gamma$,$gamma$) uc{6}{Li} have been measured at the High Intensity Gamma-Ray Source (HIGS) and the sensitivity of these cross sections to the nucleon isoscalar polarizabilities was studied. Data were collected using a q
uasi-monoenergetic 86 MeV photon beam at photon scattering angles of 40$^{circ}$--160$^{circ}$. These results are an extension of a previous measurement at a lower energy. The earlier work indicated that the uc{6}{Li}($gamma$,$gamma$) uc{6}{Li} reaction at 60 MeV provides a means of extracting the nucleon polarizabilities; this work demonstrates that the sensitivity of the cross section to the polarizabilities is increased at 86 MeV. A full theoretical treatment is needed to verify this conclusion and produce values of the polarizabilities.
Elastic scattering of photons from 12C has been investigated using quasi-monoenergetic tagged photons with energies in the range 65 - 115 MeV at laboratory angles of 60 deg, 120 deg, and 150 deg at the Tagged-Photon Facility at the MAX IV Laboratory
in Lund, Sweden. A phenomenological model was employed to provide an estimate of the sensitivity of the 12C(g,g)12C cross section to the bound-nucleon polarizabilities.
Rate-dependent effects in the electronics used to instrument the tagger focal plane at the MAX IV Laboratory were recently investigated using the novel approach of Monte Carlo simulation to allow for normalization of high-rate experimental data acqui
red with single-hit time-to-digital converters (TDCs). The instrumentation of the tagger focal plane has now been expanded to include multi-hit TDCs. The agreement between results obtained from data taken using single-hit and multi-hit TDCs demonstrate a thorough understanding of the behavior of the detector system.
