ATLAS

Abstract:

We present a 201-MHz RF cavity design for muon cooling channels with non-stressed and pre-curved Be foils to terminate the beam apertures. The Be foils are necessary to improve the cavity shunt impedance with large beam apertures needed for accommodating large transverse size muon beams. Be is a low-Z material with good electrical and thermal properties. It presents an almost transparent window to muon beams, but terminates the RF cavity electro-magnetically. Previous designs use pre-stressed flat Be foils in order to keep cavity from detuning resulting from RF heating on the window surface. Be foils are expensive, and difficult to make under pre-stress to accommodate thermal expansion. An alternative design is to use pre-curved and non-stressed Be foils where the buckling direction is known, and frequency shifts can be properly predicted. We will present mechanical simulations of the Be window designs.

Abstract:

Cross sections for e⁺p charged current deep inelastic scattering at a centre-of-mass energy of 318 GeV have been determined with an integrated luminosity of 60.9 pb^-1 collected with the ZEUS detector at HERA. The differential cross sections dσ/dQ², dσ/dx and dσ/dy for Q² > 200 GeV2 are presented. In addition, d²σ/dxdQ² has been measured in the kinematic range 280 GeV² < Q² < 17 000 GeV² and 0.008 < x < 0.42. The predictions of the Standard Model agree well with the measured cross sections. The mass of the W boson propagator is determined to be MW = 78.9 ± 2.0 (stat.) ± 1.8 (syst.) -1.8^+2.0 (PDF) GeV from a fit to dσ/dQ². The chiral structure of the Standard Model is also investigated in terms of the (1-y)² dependence of the double-differential cross section. The structure-function F2^CC has been extracted by combining the measurements presented here with previous ZEUS results from e^-p scattering, extending the measurement obtained in a neutrino-nucleus scattering experiment to a significantly higher Q² region.

Abstract:

We present a measurement of the mass difference m(Ds+) -m(D+), where both the Ds+ and D+ are reconstructed in the φπ+ decay channel. This measurement uses 11.6 pb-1 of data collected by CDF II using the new displaced-track trigger. The mass difference is found to be m(D s+)-m(D+) = 99.41±0.38(stat) ±0.21(syst) MeV/c2. copy; 2003 The American Physical Society.

Abstract:

This report describes how one can integrate the muon absorber with the focusing coils of a SFOFO muon cooling channel [1]. The absorber material must be a low Z material that reduces the muon momentum with minimum scattering. The best materials to use for muon ionization cooling absorbers are hydrogen, helium, lithium hydride, lithium, and beryllium. Hydrogen or helium in an absorber would normally be in the liquid state, Lithium hydride, lithium, and beryllium would normally be in the solid state. This report limits the absorber materials discussed to hydrogen, helium, lithium, and beryllium. In order to achieve the same level of ionization cooling with a solid absorber as a liquid hydrogen absorber, the beta of the muon beam must be reduced more than a factor of two. This affects both the designs of the absorber and the magnet around it. Reducing the beam beta reduces the momentum acceptance of the channel. Integration of a liquid hydrogen absorber and solid absorbers with a superconducting focusing solenoid is discussed. The choice of absorber material affects the design of the superconducting focusing magnet and the superconductor that is used to generate the magnetic field.