The conceptual design for a nonscaling fixed field alternating gradient accelerator suitable for charged particle therapy (the use of protons and other light ions to treat some forms of cancer) is described.

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A deuteron radio-frequency quadrupole (RFQ) is being built by the RFQ group at Peking University. It is a very compact high-current RFQ, operating at 162.5 MHz in continuous-wave mode. By optimizing the beam dynamics design, our simulations reached 98% transmission efficiency for acceleration of the 50-mA deuteron beam from 50 keV to 1 MeV, with an intervane voltage of 60 kV and a length of 1.809 m. This RFQ adopts a window-type structure, with low power consumption and sufficient mode separation, with no stabilizing rods required. Its magnetic coupling windows have been optimized by both electromagnetic simulation and the construction of an equivalent circuit model. The empirical equation based on the circuit model provides a new way to evaluate the effect of the window size on the frequency. In addition, an aluminum model of the full-length RFQ has been built and tested, and the results show good agreement with the simulations. During the tuning process, the magnetic coupling effect between quadrants was found to be unique to the window-type RFQ. We also propose a method to estimate the effects of different degrees of electric field unflatness on the beam transmission. For the cooling system design, the results of thermostructural analysis, verified by comparing results from ANSYS and CST, show that the special cooling channels provide a high cooling efficiency around the magnetic coupling windows. The maximal deformation of the structure was approximately 75 μm. The beam-loading effect caused by a high current, and the coupler design, are also discussed.

How much does politics affect relationship building? Previous experimental studies have come to vastly different conclusions – ranging from null to truly transformative effects. To explore these differences, this study replicates and extends previous research by conducting five survey experiments meant to expand our understanding of how politics does/does not shape the formation of romantic relationships. We find that people, indeed, are influenced by the politics of prospective partners; respondents evaluate those in the political out-group as being less attractive, less dateable, and less worthy of matchmaking efforts. However, these effects are modest in size – falling almost exactly in between previous study estimates. Our results shine light on a literature that has, up until this point, produced a chasm in study results – a vital task given concerns over growing levels of partisan animus in the USA and the rapidly expanding body of research on affective polarization.

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