Single π 0 production off neutrons bound in deuteron with linearly polarized photons

The quasifree γ → d → π 0 n ( p ) photon beam asymmetry, Σ , has been measured at photon energies, E γ , from 390 to 610 MeV, corresponding to center of mass energy from 1.271 to 1.424 GeV, for the first time. The data were collected in the A2 hall of the MAMI electron beam facility with the Crystal Ball and TAPS calorimeters covering pion center-of-mass angles from 49 ∘ to 148 ∘ . In this kinematic region, polarization observables are sensitive to contributions from the Δ ( 1232 ) and N(1440) resonances. The extracted values of Σ have been compared to predictions based on partial-wave analyses (PWAs) of the existing pion photoproduction database. Our comparison includes the SAID, MAID and Bonn-Gatchina analyses; while a revised SAID fit, including the new Σ measurements, has also been performed. In addition, isospin symmetry is examined as a way to predict π 0 n photoproduction observables, based on fits to published data in the channels π 0 p , π + n and π - p .

Beam-Target Helicity Asymmetry for γ[over →]n[over →]→π^{-}p in the N^{*} Resonance Region

We report the first beam-target double-polarization asymmetries in the γ+n(p)→π^{-}+p(p) reaction spanning the nucleon resonance region from invariant mass W=1500 to 2300 MeV. Circularly polarized photons and longitudinally polarized deuterons in solid hydrogen deuteride (HD) have been used with the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab. The exclusive final state has been extracted using three very different analyses that show excellent agreement, and these have been used to deduce the E polarization observable for an effective neutron target. These results have been incorporated into new partial wave analyses and have led to significant revisions for several γnN^{*} resonance photocouplings.

Study of η and η' Photoproduction at MAMI

The reactions γp→ηp and γp→η^{'}p are measured from their thresholds up to the center-of-mass energy W=1.96  GeV with the tagged-photon facilities at the Mainz Microtron, MAMI. Differential cross sections are obtained with unprecedented statistical accuracy, providing fine energy binning and full production-angle coverage. A strong cusp is observed in the total cross section for η photoproduction at the energies in the vicinity of the η^{'} threshold, W=1896  MeV (E_{γ}=1447  MeV). Within the framework of a revised ηMAID isobar model, the cusp, in connection with a steep rise of the η^{'} total cross section from its threshold, can only be explained by a strong coupling of the poorly known N(1895)1/2^{-} state to both ηp and η^{'}p. Including the new high-accuracy results in the ηMAID fit to available η and η^{'} photoproduction data allows the determination of the N(1895)1/2^{-} properties.

Precision Measurement of the p(e,e^{'}p)π^{0} Reaction at Threshold

New results are reported from a measurement of π^{0} electroproduction near threshold using the p(e,e^{'}p)π^{0} reaction. The experiment was designed to determine precisely the energy dependence of s- and p-wave electromagnetic multipoles as a stringent test of the predictions of chiral perturbation theory (ChPT). The data were taken with an electron beam energy of 1192 MeV using a two-spectrometer setup in Hall A at Jefferson Lab. For the first time, complete coverage of the ϕ_{π}^{*} and θ_{π}^{*} angles in the pπ^{0} center of mass was obtained for invariant energies above threshold from 0.5 up to 15 MeV. The 4-momentum transfer Q^{2} coverage ranges from 0.05 to 0.155 (GeV/c)^{2} in fine steps. A simple phenomenological analysis of our data shows strong disagreement with p-wave predictions from ChPT for Q^{2}>0.07 (GeV/c)^{2}, while the s-wave predictions are in reasonable agreement.

Measurement of the 1H(γ, p)π0 reaction using a novel nucleon spin polarimeter

We report the first large-acceptance measurement of polarization transfer from a polarized photon beam to a recoiling nucleon. The measurement pioneers a novel polarimetry technique, which can be applied to many other nuclear and hadron physics experiments. The commissioning reaction of 1H(γ, p)π0 in the range 0.4<Eγ<1.4  GeV validates the technique and provides essential new data to constrain the excitation spectrum of the nucleon.

Tobacco use among Pacific Islanders: risk-behavior surveys and data sets for the study of smoking behavior on Guam

OBJECTIVES

To increase awareness of data resources from the Pacific Island of Guam, and their utility for research investigations of factors that encourage or discourage smoking among Pacific Islanders, and in turn, to produce empirical findings on tobacco use among Pacific Islanders to help fill data gaps on Asian American and Pacific Islander (AAPI) tobacco use for small AAPI populations.

METHODS

Guam's 1995 and 1999 Behavioral Risk Factor Surveillance System (BRFSS) data sets were selected, as well as its 1999 Safe and Drug Free Schools and Communities Youth Risk Behavior System (YRBS) study, and a panel study of parental influences on risk behavior of middle school age youth conducted in 2000. Resultant sample sizes were 896 persons in 1995, and 506 in 1999. Guam's YRBS data sets are samples of middle school (grades 6-8) and high school youth (grades 9-12) in classrooms randomly sampled by grade level from both public and private schools. In 1999, a resultant sample of 589 high school students was obtained. In 2000, using the same sampling process as the YRBS studies but limited to public middle schools only, a specialized panel study obtained a sample of 270 middle school youth to study the influences of parents and peers on smoking and other risk behaviors.

FINDINGS

Current smoking prevalence among adult Pacific Islanders (38 percent) on Guam is similar to other Pacific islands but comparatively high to US studies. In both 1995 and 1999, Pacific Islanders were more likely to be current smokers than other ethnic communities on island, and among those ever-smoking, they were less likely to have quit (i.e., report being former smokers). The same patterns of ethnic differences between Pacific Islanders, Asians, and non-API persons were consistently found among high school, and also middle school youth. These ethnic differences may implicate factors of tobacco accessibility, cultural definitions of "childhood," and adult role modeling, as contributing forces to smoking behavior on Guam.

CONCLUSION

Pacific island communities allow for studies of ethnic-cultural influences that are not masked by factors such as acculturation, socioeconomic status, the intensity of media advertising, or urban life and its attendant conditions of minority status that affect AAPI studies in the US mainland. For tobacco control advocates and AAPI scholars across the nation, data from Guam may prove useful for investigations of differences in lifestyles, cultural beliefs or practices, and environmental exposures that encourage or discourage smoking among AAPIS, and thus help to unravel the compounding interplay between factors.

The influence of ethnicity and socioeconomic status on the use of mammography by Asian and Pacific island women on Guam

The effects of ethnicity and socioeconomic status on the use of screening mammograms were assessed for a probability sample of Chamorro, Filipino, White, and other Asian and Pacific island women residing on Guam. Using logistic regression analysis, we found that socioeconomic status significantly influenced the use of screening mammograms among Chamorro and Filipino women while strong ethnic effects remained for other Asian and Pacific island women. Age had a significant influence of the use of screening mammograms. Marital status and having a young child in the home were not significant predictor variables.