Popper's Experiment and Superluminal Communication

We comment on Tabesh Qureshi, "Understanding Popper's Experiment," AJP 73, 541 (June 2005), in particular on the implications of its section IV. We show, in the situation envisaged by Popper, that analysis solely with conventional non-relativistic quantum mechanics suffices to exclude the possibility of superluminal communication.Comment: Submitted to American Journal of Physic

Hadron cancer therapy complex employing non-scaling FFAG accelerator and fixed field gantry design

Non-scaling FFAG rings for cancer hadron therapy offer reduced physical aperture and large dynamic aperture as compared with scaling FFAGs. The variation of tune with energy implies the crossing of resonances during acceleration. Our design avoids intrinsic resonances, although imperfection resonances must be, and can be, crossed. We consider a system of three non-scaling FFAG rings for cancer therapy with 250 MeV protons and 400 MeV/u carbon ions. Hadrons are accelerated in a common RFQ and linear accelerator, and injected into the FFAG rings at .. .. . H+/C6+ ions are accelerated in the two smaller/larger rings to 31 and 250 MeV/68.8 and 400 MeV/u kinetic energy, respectively. The lattices consist of doublet cells with a straight section for RF cavities. The gantry with triplet cells accepts the whole required momentum range at fixed field. This unique design uses either high temperature super-conductors or super-conducting magnets reducing gantry size and weight. Elements with variable field at beginning and at end set the extracted beam at the correct position for a range of energies

Hadron cancer therapy complex using nonscaling fixed field alternating gradient accelerator and gantry design

Nonscaling fixed field alternating gradient (FFAG) rings for cancer hadron therapy offer reduced physical aperture and large dynamic aperture as compared to scaling FFAGs. The variation of tune with energy implies the crossing of resonances during acceleration. Our design avoids intrinsic resonances, although imperfection resonances must be crossed. We consider a system of three nonscaling FFAG rings for cancer therapy with 250 MeV protons and 400   MeV/u carbon ions. Hadrons are accelerated in a common radio frequency quadrupole and linear accelerator, and injected into the FFAG rings at v/c=0.1294. H^{+}/C^{6+} ions are accelerated in the two smaller/larger rings to 31 and 250  MeV/68.8 and 400   MeV/u kinetic energy, respectively. The lattices consist of doublet cells with a straight section for rf cavities. The gantry with triplet cells accepts the whole required momentum range at fixed field. This unique design uses either high-temperature superconductors or superconducting magnets reducing gantry magnet size and weight. Elements with a variable field at the beginning and at the end set the extracted beam at the correct position for a range of energies

HELIUM THREE

A review is given of the present state of knowledge concerning the condensed phases of He{sup 3}. Attention is confined to the pure substance, and emphasis is placed upon the theoretical understanding of the material

BETA-RAY SPECTROMETER WITH REDUCED SPHERICAL ABERRATION

Modern {beta}-ray spectrometers are based upon the concept, first introduced by Svartholm and Siegbahn in 1946, of focusing in both the radial and vertical directions. The theory of axially symmetric devices has been carefully studied by a large number of workers, culminating in the analysis, in 1956, of Lee-Whiting and Taylor. These last authors calculate aberrations through the sixth order and show that by appropriate choice of the magnetic field a spectrometer can be designed with a relatively large transmission and a high resolution. The acceptable transmission is remarkable because the second-order 'spherical' aberration in the median plane of the image cannot be made to vanish identically, and consequently the design is forced to a tall thin aperture (or a slightly less advantageous short wide aperture) which a priori would seem to imply a low transmission. It is the purpose of this communication to show that if the arbitrary restriction to axially symmetric fields is removed, then both the radial and the vertical contributions to the 'spherical' aberration can be made to vanish in second order. That azimuthally varying field (AVF) afford the freedom to accomplish this end may well be suspected in view of the technological revolution that the concept has brought to other particle-handling devices