Low- and intermediate-energy nucleon-nucleon interactions and the analysis of deuteron photodisintegration within the dispersion relation technique

The nucleon-nucleon interaction in the region of the nucleon kinetic energy up to 1000 MeV is analysed together with the reaction $\gamma d \to pn$ in the photon energy range $E_{\gamma}=0-400$ MeV. Nine nucleon-nucleon $s$-channel partial amplitudes are reconstructed in the dispersion relation $N/D$ method: $^1S_0$, $^3S_1-^3D_1$, $^3P_0$, $^1P_1$, $^3P_1$, $^3P_2$, $^1D_2$, $^3D_2$ and $^3F_3$. Correspondingly, the dispersive representation of partial amplitudes $N\Delta \to pn$, $NN^* \to pn$ and $NN\pi \to pn$ is given. Basing on that, we have performed parameter-free calculation of the amplitude $\gamma d \to pn$, taking into account: $(i)$ pole diagram, $(ii)$ nucleon-nucleon final-state rescattering $\gamma d \to pn \to pn$, and $(iii)$ inelastic final-state rescatterings $\gamma d \to N\Delta(1232) \to pn$, $\gamma d \to NN^*(1400) \to pn$ and $\gamma d \to NN\pi \to pn$. The $\gamma d \to pn$ partial amplitudes for nine above-mentioned channels are found. It is shown that the process $\gamma d \to pn \to pn$ is significant for the waves $^1S_0$, $^3P_0$, $^3P_1$, at $E_{\gamma} =50 -100$ MeV, while $\gamma d \to N\Delta \to pn$ for the waves $^3P_2$, $^1D_2$,$^3F_3$ dominates at $E_{\gamma} > 300$ MeV. Meson exchange current contributions into the deuteron disintegration are estimated: they are significant at $E_\gamma =100-400$ MeV.Comment: 22 pages, LaTeX, epsfig.sty, tabl

Cross-Calibration of the XMM-Newton EPIC pn & MOS On-Axis Effective Areas Using 2XMM Sources

We aim to examine the relative cross-calibration accuracy of the on-axis effective areas of the XMM-Newton EPIC pn and MOS instruments. Spectra from a sample of 46 bright, high-count, non-piled-up isolated on-axis point sources are stacked together, and model residuals are examined to characterize the EPIC MOS-to-pn inter-calibration. The MOS1-to-pn and MOS2-to-pn results are broadly very similar. The cameras show the closest agreement below 1 keV, with MOS excesses over pn of 0-2% (MOS1/pn) and 0-3% (MOS2/pn). Above 3 keV, the MOS/pn ratio is consistent with energy-independent (or only mildly increasing) excesses of 7-8% (MOS1/pn) and 5-8% (MOS2/pn). In addition, between 1-2 keV there is a `silicon bump' - an enhancement at a level of 2-4% (MOS1/pn) and 3-5% (MOS2/pn). Tests suggest that the methods employed here are stable and robust. The results presented here provide the most accurate cross-calibration of the effective areas of the XMM-Newton EPIC pn and MOS instruments to date. They suggest areas of further research where causes of the MOS-to-pn differences might be found, and allow the potential for corrections to and possible rectification of the EPIC cameras to be made in the future.Comment: 8 Pages, 2 figures (3 panels), 1 table. Accepted for publication in A&

The role of planets in shaping planetary nebulae

In 1997 Soker laid out a framework for understanding the formation and shaping of planetary nebulae (PN). Starting from the assumption that non-spherical PN cannot be formed by single stars, he linked PN morphologies to the binary mechanisms that may have formed them, basing these connections almost entirely on observational arguments. In light of the last decade of discovery in the field of PN, we revise this framework, which, although simplistic, can still serve as a benchmark against which to test theories of PN origin and shaping. Within the framework, we revisit the role of planets in shaping PN. Soker invoked a planetary role in shaping PN because there are not enough close binaries to shape the large fraction of non-spherical PN. In this paper we adopt a model whereby only ~20% of all 1-8 solar mass stars make a PN. This reduces the need for planetary shaping. Through a propagation of percentages argument, and starting from the assumption that planets can only shape mildly elliptical PN, we conclude, like in Soker, that ~20% of all PN were shaped via planetary and other substellar interactions but we add that this corresponds to only ~5% of all 1-8 solar mass stars. This may be in line with findings of planets around main sequence stars. PN shaping by planets is made plausible by the recent discovery of planets that have survived interactions with red giant branch (RGB) stars. Finally, we conclude that of the ~80% of 1-8 solar mass stars that do not make a PN, about one quarter do not even ascend the AGB due to interactions with stellar and substellar companions, while three quarters ascend the AGB but do not make a PN. Once these stars leave the AGB they evolve normally and can be confused with post-RGB, extreme horizontal branch stars. We propose tests to identify them.Comment: 23 pages, accepted by PAS

Gluonic effects in eta and eta-prime physics

We review the theory and phenomenology of the axial U(1) problem with emphasis on the role of gluonic degrees of freedom in eta and eta' production processes, especially the low-energy pN -> pN eta and pN -> pN eta' reactions.Comment: 20 pages, 2 figures, Invited talk at the WASA Workshop on Eta Physics, October 2001, Uppsala, Swede

Quantum Transport Characteristics of Lateral pn-Junction of Single Layer TiS3

Using density functional theory and nonequilibrium Greens functions-based methods we investigated the electronic and transport properties of monolayer TiS3 pn-junction. We constructed a lateral pn-junction in monolayer TiS3 by using Li and F adatoms. An applied bias voltage caused significant variability in the electronic and transport properties of the TiS3 pn-junction. In addition, spin dependent current-voltage characteristics of the constructed TiS3 pn-junction were analyzed. Important device characteristics were found such as negative differential resistance and rectifying diode behaviors for spin-polarized currents in the TiS3 pn-junction. These prominent conduction properties of TiS3 pn-junction offer remarkable opportunities for the design of nanoelectronic devices based on a recently synthesized single-layered material