Search Results (16 total)

The design of a low-energy (4 GeV) neutrino factory (NF) is described, along with its expected performance. The neutrino factory uses a high-energy proton beam to produce charged pions. The π^± decay to produce muons (μ^±), which are collected, accelerated, and stored in a ring with long straight sections. Muons decaying in the straight sections produce neutrino beams. The scheme is based on previous designs for higher energy neutrino factories, but has an improved bunching and phase rotation system, and new acceleration, storage ring, and detector schemes tailored to the needs of the lower energy facility. Our simulations suggest that the NF scheme we describe can produce neutrino beams generated by ∼1.4×10²¹ μ⁺ per year decaying in a long straight section of the storage ring, and a similar number of μ^- decays.

We present results on the production of direct photons, π⁰, and η mesons on nuclear targets at large transverse momenta (p_T). The data are from 530 and 800  GeV/c proton beams and 515  GeV/c π^- beams incident upon copper and beryllium targets that span the kinematic range of 1.0<p_T≲10  GeV/c at central rapidities.

Measurements of the production of high transverse momentum direct photons by a 515  GeV/c π^- beam and 530 and 800  GeV/c proton beams in interactions with beryllium and hydrogen targets are presented. The data span the kinematic ranges of 3.5<p_T<12  GeV/c in transverse momentum and 1.5 units in rapidity. The inclusive direct-photon cross sections are compared with next-to-leading-order perturbative QCD calculations and expectations based on a phenomenological parton-k_T model.

We present results on the production of high transverse momentum π⁰ and η mesons in π^-p and π^-Be interactions at 515 GeV/c. The data span the kinematic ranges 1<p_T<11 GeV/c in transverse momentum and -0.75<~y_cm<~0.75 in rapidity. The inclusive π⁰ cross sections are compared with next-to-leading order QCD calculations and to expectations based on a phenomenological parton-k_T model.

We present measurements of the production of high transverse momentum π⁰ and η mesons in pp and pBe interactions at 530 and 800 GeV/c. The data span the kinematic ranges: 1<p_T <10 GeV/c in transverse momentum and 1.5 units in rapidity. The inclusive π⁰ cross sections are compared with next-to-leading order QCD calculations and to expectations based on a phenomenological parton-k_T model.

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.

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)].

Inclusive π⁰ and direct-photon cross sections in the kinematic range 3.5<p_T<12 GeV/c with central rapidities ( y_cm) are presented for 530 and 800 GeV/c proton beams and a 515 GeV/c π^- beam incident on Be targets. Current next-to-leading-order perturbative QCD calculations fail to adequately describe the data for conventional choices of scales. Kinematic distributions from these hard scattering events provide evidence that the interacting partons carry significant initial-state parton transverse momentum ( k_T). Incorporating these k_T effects phenomenologically greatly improves the agreement between calculations and the measured cross sections.

We present results on the production of high transverse momentum charm mesons in collisions of 515 GeV/c negative pions with beryllium and copper targets. The experiment recorded a large sample of events containing high transverse momentum (p_T) showers detected in an electromagnetic calorimeter. From these data, a sample of charm mesons has been reconstructed via their decay into the fully charged Kππ mode. A measurement of the single inclusive transverse momentum distribution of charged D mesons from 1 to 8 GeV/c is presented. An extrapolation of the measured differential cross section yields an integrated D^± cross section of 11.4±2.7(stat)±3.3(syst) μb per nucleon for D^± mesons with x_F>0. The data are compared with expectations based upon next-to-leading-order perturbative QCD, as well as with results from PYTHIA. We also compare our integrated D^± cross section with measurements from other experiments.

We present the results of a study of hadronic jets produced in association with direct photons and π⁰'s at large transverse momenta in π^-Be and pBe collisions at 500 GeV/c. Using primarily charged particles to characterize the properties of the recoiling jets, we compare their fragmentation and angular distributions, and their correlation with the trigger particle, for both the γ and π⁰ event samples. We also compare the data with QCD calculations that incorporate current parton distribution functions.

We present results from the initial run of Fermilab experiment E706. The data include incident π^- and p beams at 500 GeV/c on Be and Cu targets, and span the kinematic ranges of transverse momentum and rapidity of 3.5≤p_T≤10 GeV/c and -0.7≤y_c.m.≤0.7, respectively. We have measured cross sections for π⁰ and direct-photon production, as well as the η / π⁰ production ratio. From the data on Be and Cu, we have extracted the nuclear dependence of π⁰ production, parametrized as A^α. The cross sections are compared with next-to-leading-log QCD predictions for different choices of the QCD momentum scales and several sets of parton distribution functions.

The relative photodetachment cross section for decay into the H(N=2) channel by the ¹P° shape resonance in H^- was measured, as well as that for decay into all channels. The branching ratio σ(N=2)/σ(total) was computed for a series of energies between 10.95 and 11.3 eV after normalizing the cross sections to theoretical peak amplitudes. The maximum branching ratio (≊0.8) appears at an energy about 20 meV higher than the central energy of the resonance. Results are compared with recent theoretical calculations.

We present new measurements of π⁰ production at high transverse momenta (p_T) for π^- and p interactions on Be and Cu targets at 500 GeV/c. The observed dependence of the yields as a function of p_T and rapidity (y) is compared with expectations from leading-log QCD over a kinematic range in which the inclusive cross sections fall by more than 4 order of magnitude.

We report new measurements of inclusive direct photon production at high transverse momenta (p_T) for π^- and p interactions on Be at 500 GeV/c. The yields as a function of p_T and rapidity (y) are in good agreement with expectations from next-to-leading-log QCD calculations employing recently extracted quark and gluon structure functions.

The results are presented of further studies of the effects of electric fields on the photodetachment cross section of H^-, for both π and σ polarization. Data are fitted to the theory of Rau and Wong [Phys. Rev. A 37, 632 (1988)], which predicts a modulation about the zero-field cross section. Agreement is good for π polarization, but the predicted profile for σ polarization does not appear to match the data quite as well.

The inelastic scattering of 162-MeV pions was studied over the angular range 35° to 100° in the laboratory system and the data were analyzed with a model that incorporates shell-model wave functions into a distorted-wave impulse approximation formalism. Reduced transition probabilities were obtained for low-lying levels and compared with information previously reported. In addition, evidence is obtained for theoretically predicted levels with high spin that have not been observed previously.