Collider design issues based on proton-driven plasma wakefield acceleration

Recent simulations have shown that a high-energy proton bunch can excite strong plasma wakefields and accelerate a bunch of electrons to the energy frontier in a single stage of acceleration. It therefore paves the way towards a compact future collider design using the proton beams from existing high-energy proton machines, e.g. Tevatron or the LHC. This paper addresses some key issues in designing a compact electron-positron linear collider and an electron-proton collider based on existing CERN accelerator infrastructure

Solar Magnetic Tracking. I. Software Comparison and Recommended Practices

Feature tracking and recognition are increasingly common tools for data analysis, but are typically implemented on an ad-hoc basis by individual research groups, limiting the usefulness of derived results when selection effects and algorithmic differences are not controlled. Specific results that are affected include the solar magnetic turnover time, the distributions of sizes, strengths, and lifetimes of magnetic features, and the physics of both small scale flux emergence and the small-scale dynamo. In this paper, we present the results of a detailed comparison between four tracking codes applied to a single set of data from SOHO/MDI, describe the interplay between desired tracking behavior and parameterization of tracking algorithms, and make recommendations for feature selection and tracking practice in future work.Comment: In press for Astrophys. J. 200

Low Power Measurements on a Finger Drift Tube Linac

The efficiency of RFQs decreases at particle energies higher than a few MeV/u and thus typically DTL structures are used in this energy region. However, the rf field in the gap always has a defocusing influence on the beam. In order to compensate this effect, fingers with quadrupole symmetry were added to the drift tubes, the focusing fingers do not need an additional power source or feed through. Beam dynamics have been studied with the code RFQSIM. Detailed analysis of the field distribution was done and the geometry of the finger array has been optimized with respect to beam dynamics. A prototype cavity with finger drift tubes was built and low power measurements were done. In this contribution, the results of the rf simulation with Microwave Studio are compared to bead perturbation measurements and the focusing effect on the beam is discussed

Investigations of OTR screen surfaces and shapes

Optical transition radiation (OTR) has proven to be a flexible and effective tool for measuring a wide range of beam parameters, in particular the beam divergence and the transverse beam profile. It is today an established and widely used diagnostic method providing linear real-time measurements. Measurements in the CLIC Test Facility (CTF3) showed that the performance of the present profile monitors is limited by the optical acceptance of the imaging system. In this paper, two methods to improve the systems' performance are presented and results from measurements are shown. First, the influence of the surface quality of the OTR screen itself is addressed. Several possible screen materials have been tested to which different surface treatment techniques were applied. Results from the measured optical characteristics are given. Second, a parabolic-shaped screen support was investigated with the aim of providing an initial focusing of the emitted radiation and thus to reduce the problem of aperture limitation

Extension of the Measurement Capabilities of the Quadrupole Resonator

The Quadrupole Resonator, designed to measure the surface resistance of superconducting samples at 400 MHz has been refurbished. The accuracy of its RF-DC compensation measurement technique is tested by an independent method. It is shown that the device enables also measurements at 800 and 1200 MHz and is capable to probe the critical RF magnetic field. The electric and magnetic field configuration of the Quadrupole Resonator are dependent on the excited mode. It is shown how this can be used to distinguish between electric and magnetic losses.Comment: 6 pages, g figure

Conditional quantum-state transformation at a beam splitter

Using conditional measurement on a beam splitter, we study the transformation of the quantum state of the signal mode within the concept of two-port non-unitary transformation. Allowing for arbitrary quantum states of both the input reference mode and the output reference mode on which the measurement is performed, we show that the non-unitary transformation operator can be given as an $s$-ordered operator product, where the value of $s$ is entirely determined by the absolute value of the beam splitter reflectance (or transmittance). The formalism generalizes previously obtained results that can be recovered by simple specification of the non-unitary transformation operator. As an application, we consider the generation of Schr\"odinger-cat-like states. An extension to mixed states and imperfect detection is outlined.Comment: 7 Postscript figures, using Late

Enhancement by prolactin of carcinogen induced mammary cancerigenesis in the male rat.

Mammary tumours were induced in 3 groups of male Long-Evans rats by a series of 6 fortnightly gastric intubations of 7,12-dimethylbenzanthracene. Two weeks before the initial carcinogen treatment one group of rats was grafted with 3 pituitary homografts underneath the kidney capsule of each recipient (hyperprolactinaemia). A second group, 2 weeks before the initial carcinogen treatment and for the duration of the study (35 weeks), were injected 4 X weekly with 2-Br-alpha-ergocryptine (CB-154) (hypoprolactinaemia). A third group of rats served as controls. A significant increase in the incidence of mammary tumours and a reduced latency period of tumour appearance in the hyperprolactinaemia group, when compared with the controls, were observed in this study. Mammary tumour incidence and latency period of tumour appearance in the hypoprolactinaemia group, however, did not differ significantly from controls. Thus, an increased secretion of pituitary prolactin in rats appears to be an important enhancing endocrinic condition in carcinogenesis of the male mammary gland