A measurement of the axial form factor of the nucleon by the p(e,e'pi+)n reaction at W=1125 MeV

The reaction p(e,e'pi+)n was measured at the Mainz Microtron MAMI at an invariant mass of W=1125 MeV and four-momentum transfers of Q^2=0.117, 0.195 and 0.273 (GeV/c)^2. For each value of Q^2, a Rosenbluth separation of the transverse and longitudinal cross sections was performed. An effective Lagrangian model was used to extract the `axial mass' from experimental data. We find a value of M_A=(1.077+-0.039) GeV which is (0.051+-0.044) GeV larger than the axial mass known from neutrino scattering experiments. This is consistent with recent calculations in chiral perturbation theory.Comment: 14 pages, 5 figures, uses elsart.cl

High-precision Studies of the 3^{\bf{3}}He(e,e′^{\bf{\prime}}p) Reaction at the Quasielastic Peak

Precision studies of the reaction $^{3}$He(e,e$^\prime$p) using the three-spectrometer facility at the Mainz microtron MAMI are presented. All data are for quasielastic kinematics at $|\vec{q} | =685$ MeV/c. Absolute cross sections were measured at three electron kinematics. For the measured missing momenta range from 10 to 165 MeV/c, no strength is observed for missing energies higher than 20 MeV. Distorted momentum distributions were extracted for the two-body breakup and the continuum. The longitudinal and transverse behavior was studied by measuring the cross section for three photon polarizations. The longitudinal and transverse nature of the cross sections is well described by a currently accepted and widely used prescription of the off-shell electron-nucleon cross-section. The results are compared to modern three-body calculations and to previous data.Comment: 4 pages, 3 figures. Submitted for publication in Phys. Rev. Let

Risk of coronary stenosis after adjuvant radiotherapy for breast cancer

Purpose Adjuvant radiotherapy (RT) for breast cancer is associated with an increased risk of ischemic heart disease. We examined the risk of coronary artery stenosis in a large cohort of women with breast cancer receiving adjuvant RT. Methods A cohort of women diagnosed with breast cancer between 1992 and 2012 in three Swedish health care regions (n = 57,066) were linked to the Swedish Coronary Angiography and Angioplasty Registry (SCAAR) to identify women receiving RT who subsequently underwent a percutaneous coronary intervention (PCI) due to coronary stenosis. Cox regression analyses were performed to examine risk of a coronary intervention and competing risk analyses were performed to calculate cumulative incidence. Results A total of 649 women with left-sided breast cancer and 494 women with right-sided breast cancer underwent a PCI. Women who received left-sided RT had a significantly higher risk of a PCI in the left anterior descending artery (LAD) compared to women who received right-sided RT, hazard ratio (HR) 1.44 (95% confidence interval [CI] 1.21-1.77, p < 0.001). For the proximal, mid, and distal LAD, the HRs were 1.60 (95% CI 1.22-2.10), 1.38 (95% CI 1.07-1.78), and 2.43 (95% CI 1.33-4.41), respectively. The cumulative incidence of coronary events at 25 years from breast cancer diagnosis were 7.0% in women receiving left-sided RT and 4.4% in women receiving right-sided RT. Conclusion Implementing and further developing techniques that lower cardiac doses is important in order to reduce the risk of long-term side effects of adjuvant RT for breast cancer.Peer reviewe

Generalized seniority scheme in light Sn isotopes

The yrast generalized seniority states are compared with the corresponding shell model states for the case of the Sn isotopes $^{104-112}$Sn. For most of the cases the energies agree within 100 keV and the overlaps of the wave functions are greater than 0.7.Comment: 8 pages, revtex. Submitted to Phys. Rev.

Principles of optical design of the SM beamline at the CLS

Abstract. The spectromicroscopy beamline (SM) at the Canadian Light Source (CLS) will provide 100 -2000 eV photons in a high brightness, high flux, medium resolution and small spot size beam. The beamline consists of an advanced elliptically polarized undulator (EPU) source and a novel entrance slit-less plane grating monochromator which feeds two branch lines, one optimized for scanning transmission X-ray microscopy (STXM), the other for X-ray photoemission electron microscopy (X-PEEM). This article outlines the beamline design strategy, and discusses the design optimization relative to the requirements for state-of-the-art STXM and X-PEEM. DESIGN OBJECTIVES AND CONSTRAINTS Development of third generation SR sources, enhanced quality soft x-ray optics, and advances in beamline design have lead to the construction of several successful spectromicroscopy (SM) facilities around the world [1]. The SM facility at the Canadian Light Source (CLS), a dedicated soft x-ray beamline and associated scanning transmission x-ray microscope (STXM) and x-ray photoemission electron microscope (X-PEEM), will begin operation in 2004. Here we describe the design principles and solutions adopted to optimize the beamline for these two microscopies. There is a substantial difference in image formation for these two techniques. In STXM, the source is demagnified by a Fresnel zone plate (FZP) and the ultimate spatial resolution is defined by the outmost zone width, or ~30nm at current stage of FZP fabrication [2]. To keep such ultimate spot size, the phase accepted by FZP needs to be limited to a single diffraction mode or λ (wavelength of incoming radiation) [3]. As this phase space is much smaller than the emittance of existed SR sources, reduced horizontal phase acceptance can be traded for energy resolving power and overall simplicity. Following the design of the X1A spectromicroscopy beamline at the National Synchrotron Light Source (NSLS), the horizontal dispersing spherical grating monochromator has proved to be a successful choice for several STXM [3][4][5]. In PEEM, the image is formed by magnified projection of low energy photoelectrons with electrostatic or magnetic electron lenses and recorded with a CCD camera. The dominant chromatic aberrations reduce spatial resolution for most PEEM to ~50 nm in the soft x-ray regime. When this spatial resolution is matched to a megapixel high sensitivity CCD the field of view is of order 30-50 µm. Such moderate spot size can be obtained without any phase (source emittance) loss. The figure of merit analysis of different optical schemes was performed by Weiss et al [6] who concluded that a collimated plane grating monochromator is the optimal choice and further, that it allows further beam size reduction if needed . To find the optical scheme which best suits both experiments we compared two design concepts, namely a horizontally dispersed spherical grating monochromator (HD-SGM) and a collimated plane grating monochromator with vertical dispersion (PGM) with primary design goal for highest possible on-sample flux in each microscope, with a resolving power exceeding 3000 and covering the energy range 250-2000eV. The results of the comparison follow by a brief presentation of the optical properties of the PGM-based beamline, which was chosen as a best compromise. The ID10 sector was allocated for the CLS-SM facility, which limits the total length of the beamline to 37m. The lattice parameters (β x =8.5m, β y =4.6m, η x =0.15m, for ε x =18nmrad and assuming 0.2% coupling as projected for 2008 operation) result in electron beam size (FWHM) ∆x=990µ and ∆y=30µ [7]. Chiral molecules, magnetic ordering, sample texture and film orientation are among the scientific topics to be studied so full polarization contro

The f_LT Response Function of D(e,e'p)n at Q^2=0.33(GeV/c)^2

The interference response function f_LT (R_LT) of the D(e,e'p)n reaction has been determined at squared four-momentum transfer Q^2 = 0.33 (GeV/c)^2 and for missing momenta up to p_miss= 0.29 (GeV/c). The results have been compared to calculations that reproduce f_LT quite well but overestimate the cross sections by 10 - 20% for missing momenta between 0.1 (GeV/c) and 0.2 (GeV/c) .Comment: 12 Pages, 10 figure

Road salt emissions: A comparison of measurements and modelling using the NORTRIP road dust emission model

AbstractDe-icing of road surfaces is necessary in many countries during winter to improve vehicle traction. Large amounts of salt, most often sodium chloride, are applied every year. Most of this salt is removed through drainage or traffic spray processes but a certain amount may be suspended, after drying of the road surface, into the air and will contribute to the concentration of particulate matter. Though some measurements of salt concentrations are available near roads, the link between road maintenance salting activities and observed concentrations of salt in ambient air is yet to be quantified. In this study the NORTRIP road dust emission model, which estimates the emissions of both dust and salt from the road surface, is applied at five sites in four Nordic countries for ten separate winter periods where daily mean ambient air measurements of salt concentrations are available. The model is capable of reproducing many of the salt emission episodes, both in time and intensity, but also fails on other occasions. The observed mean concentration of salt in PM10, over all ten datasets, is 4.2 μg/m3 and the modelled mean is 2.8 μg/m3, giving a fractional bias of −0.38. The RMSE of the mean concentrations, over all 10 datasets, is 2.9 μg/m3 with an average R2 of 0.28. The mean concentration of salt is similar to the mean exhaust contribution during the winter periods of 2.6 μg/m3. The contribution of salt to the kerbside winter mean PM10 concentration is estimated to increase by 4.1 ± 3.4 μg/m3 for every kg/m2 of salt applied on the road surface during the winter season. Additional sensitivity studies showed that the accurate logging of salt applications is a prerequisite for predicting salt emissions, as well as good quality data on precipitation. It also highlights the need for more simultaneous measurements of salt loading together with ambient air concentrations to help improve model parameterisations of salt and moisture removal processes

Nucleon-Nucleon Correlations and Two-Nucleon Currents in Exclusive (e,e′NNe,e'NN) Reactions

The contributions of short-range nucleon-nucleon (NN) correlations, various meson exchange current (MEC) terms and the influence of $\Delta$ isobar excitations (isobaric currents, IC) on exclusive two-nucleon knockout reactions induced by electron scattering are investigated. The nuclear structure functions are evaluated for nuclear matter. Realistic NN interactions derived in the framework of One-Boson-Exchange model are employed to evaluate the effects of correlations and MEC in a consistent way. The correlations correlations are determined by solving the Bethe-Goldstone equation. This yields significant contributions to the structure functions W_L and W_T of the (e,e'pn) and (e,e'pp) reactions. These contributions compete with MEC corrections originating from the $\pi$ and $\rho$ exchange terms of the same interaction. Special attention is paid to the so-called 'super parallel' kinematics at momentum transfers which can be measured e.g. at MAMI in Mainz.Comment: 14 pages, 8 figures include