Search Results (17 total)

An analysis of inclusive pion production in proton-beryllium collisions at 6.4, 12.3, and 17.5 GeV/c proton beam momentum has been performed. The data were taken by Experiment 910 at the Alternating Gradient Synchrotron at the Brookhaven National Laboratory. The differential π⁺ and π^- production cross sections (d²σ/dpdΩ) were measured up to 400 mrad in θ_π and up to 6 GeV/c in p_π. The measured cross section was fit with a Sanford-Wang parametrization.

We describe the status of our effort to realize a first neutrino factory and the progress made in understanding the problems associated with the collection and cooling of muons towards that end. We summarize the physics that can be done with neutrino factories as well as with intense cold beams of muons. The physics potential of muon colliders is reviewed, both as Higgs factories and compact high-energy lepton colliders. The status and time scale of our research and development effort is reviewed as well as the latest designs in cooling channels including the promise of ring coolers in achieving longitudinal and transverse cooling simultaneously. We detail the efforts being made to mount an international cooling experiment to demonstrate the ionization cooling of muons.

Differential cross sections are presented for the inclusive production of charged pions in the momentum range 0.1–1.2 GeV/c in interactions of 12.3 and 17.5 GeV/c protons with Be, Cu, and Au targets. The measurements were made by Experiment 910 at the Alternating Gradient Synchrotron (AGS) at Brookhaven National Laboratory. The cross sections are presented as a function of pion total momentum and production polar angle θ with respect to the beam.

The status of the research on muon colliders is discussed and plans are outlined for future theoretical and experimental studies. Besides work on the parameters of a 3–4 and 0.5 TeV center-of-mass (COM) energy collider, many studies are now concentrating on a machine near 0.1 TeV (COM) that could be a factory for the s-channel production of Higgs particles. We discuss the research on the various components in such muon colliders, starting from the proton accelerator needed to generate pions from a heavy-Z target and proceeding through the phase rotation and decay (π→μν_μ) channel, muon cooling, acceleration, storage in a collider ring, and the collider detector. We also present theoretical and experimental R&D plans for the next several years that should lead to a better understanding of the design and feasibility issues for all of the components. This report is an update of the progress on the research and development since the feasibility study of muon colliders presented at the Snowmass '96 Workshop [R. B. Palmer, A. Sessler, and A. Tollestrup, Proceedings of the 1996 DPF/DPB Summer Study on High-Energy Physics (Stanford Linear Accelerator Center, Menlo Park, CA, 1997)].

The requirements for the generation of forward directed Smith-Purcell emission from relativistic electrons are introduced, and the first experimental evidence of this phenomenon is presented. The experiments were conducted with a 2.8 MeV/ c electron beam interacting with a 1 cm period grating. Radiation emitted in two bands with wavelengths ranging from 600 to 650 μm and 1.2 to 1.7 mm were measured. Grating period to wavelength ratios were as high as 16. The measured intensities are higher than that predicted by incoherent emission.

High-statistics data from two exposures of the BNL 7-foot deuterium bubble chamber to a wide-band-neutrino beam with an average energy of 1.6 GeV were analyzed for exclusive pion production in charged-current neutrino-deuterium interactions. For the single-pion production reactions, the properties of Δ⁺⁺ production and decay as well as the final results of an isospin analysis are presented. New results for single-pion and multipion production are also presented.

We report on a high-statistics bubble-chamber experiment using the Fermilab 15-ft bubble chamber filled with a heavy neon/hydrogen mixture exposed to a wide-band neutrino beam. In a sample of 106 000 ν_μ &>0.3 GeV/c) and a negative muon were observed. After corrections, the rate for opposite-sign dilepton production for ν_μ charged-current events is (0.52±0.09)%. The E_ν dependence of this rate from threshold to ≊200 GeV is presented. The kinematic distributions and strange-particle content of the dilepton events are consistent with those expected from charm-particle production in neutrino interactions. A total of 58 neutral strange particles (Λ→pπ^-, K_S⁰→π⁺π^-) are observed in these events, where less than 16 are expected from conventional charged-current interactions. The presence of a significant excess of Λ’s is evidence for substantial charmed-baryon production.

We have measured the cross-section ratio R=σ(νpπ^-) / σ(μ^-pπ⁺)=0.11±0.023, 0.13±0.023, 0.15±0.025 for M_pπ<1.4, 1.6, 2.0 GeV, respectively, in the energy range 0.4<E_ν<3.0 GeV. The data are consistent with various weak one-pion production models incorporating the Weinberg-Salam structure of neutral currents.

Strange-particle production in charged-current and neutral-current neutrino interactions has been studied using the BNL 7-foot deuterium bubble chamber. A total of 37 charged-current and 9 neutral-current events in the data sample contain one or more strange particles. Three events have ΔS≠0. The measured total rate for neutral V⁰ production in charged-current interactions is (4.2±1.0)%. Cross sections are given for low-multiplicity reactions involving neutral strange particles.

A search for neutrino oscillations in a wide-band neutrino beam at Fermilab with use of the 15-ft bubble chamber is reported. No evidence is found for neutrino oscillations and upper limits are set on the mixing angles and neutrino mass differences in the transitions ν_μ→ν_e, ν_μ→ν_τ, and ν_e→ν_^∼e, where ∼e denotes "not e."

The quasielastic reaction ν_μn→μ^-p was studied in an experiment using the BNL 7-foot deuterium bubble chamber exposed to the wide-band neutrino beam with an average energy of 1.6 GeV. A total of 1138 quasielastic events in the momentum-transfer range Q²=0.06-3.00 (GeV/c)² were selected by kinematic fitting and particle identification and were used to extract the axial-vector form factor F_A(Q²) from the Q² distribution. In the framework of the conventional V-A theory, we find that the dipole parametrization is favored over the monopole. The value of the axial-vector mass M_A in the dipole parametrization is 1.07±0.06 GeV, which is in good agreement with both recent neutrino and electroproduction experiments. In addition, the standard assumptions of conserved vector current and no second-class currents are checked.

In a broadband neutrino exposure of the Fermilab 15-ft bubble chamber, we observe the production of the Σ_c⁺⁺(2426) charmed baryon followed by its decay to Λ_c⁺(2260) and π⁺. We find the mass of the Λ_c⁺ to be 2257±10 MeV and the m(Σ_c⁺⁺)-m(Λ_c⁺) mass difference to be 168±3 MeV. Previously unseen two-body decay modes of the Λ_c⁺(2260) are observed.

We have observed 34 events with visible strange-particle production out of a total charged-current sample of 4500 events in a wide-band neutrino exposure of the Brookhaven National Laboratory 7-ft bubble chamber filled with H₂ or D₂. Three events were uniquely identified as having single-strange-particle production, two with ΔS=-ΔQ. In both ΔS=-ΔQ events we observe the Λ_c⁺(2260), which in one case decays to Λπ⁺π⁺π^- and in the second case to pK̅ ⁰π^-π⁺. Production rates are given.

We have observed eleven events of the reaction ν_μe^-→ν_μe^- in a sample of 106 000 charged-current neutrino interactions in a heavy neon-hydrogen mixture in the 15-ft. bubble chamber at Fermilab. We obtain a cross section for this process of [(1.8±0.8)×10^-42 cm²/GeV]E_ν. This result is in good agreement with the prediction of the Weinberg-Salam model with sin²θ_W=0.2.

We have observed the production of the D⁰ meson by neutrinos followed by the decay D⁰→K_S⁰+π⁺+π^-. Correcting for detection efficiencies and K⁰ decay branching ratios, we find that the production of the D⁰ followed by decay into K⁰π⁺π^- corresponds to (0.7 ± 0.2)% of all charged-current neutrino interactions.

We present upper limits on the production of heavy leptons (L^±) by neutrinos via the process ν_μ+Ne→L^±+⋯, L^±→e^±+ν+ν̅ . These limits imply that the L^- and L⁺, if they couple in full strength to ν_μ, are heavier than 7.5 and 9 GeV, respectively. They also imply that the coupling strength ν_μ to the recently discovered 1.9-GeV heavy lepton τ is less than 0.025 of the normal ν_μ-μ coupling.