Proton, deuteron, and triton emission in 14N+Ag interactions at an energy of 52 MeV per nucleon

The inclusive energy spectra and multiplicities of p, d, and t from the reactions ¹⁴N(Ag, X), X=p, d, t at E/A=52 MeV are measured. The experimental data are compared with the results obtained within the Dubna version of the cascade model and are analyzed on the basis of the moving-source model.     

On the existence of infinite-dimensional invariant tori of nonlinear countable systems of difference-differential equations

In the space of bounded number sequences, we establish sufficient conditions for the existence of invariant tori for nonlinear countable systems of difference-differential equations defined on infinite-dimensional tori and containing an infinite set of constant deviations of a scalar argument.     

Observation of an exotic S = +1 baryon in exclusive photoproduction from the deuteron

In an exclusive measurement of the reaction gammad-->K(+)K(-)pn, a narrow peak that can be attributed to an exotic baryon with strangeness S=+1 is seen in the K(+)n invariant mass spectrum. The peak is at 1.542+/-0.005 GeV/c(2) with a measured width of 0.021 GeV/c(2) FWHM, which is largely determined by experimental mass resolution. The statistical significance of the peak is (5.2+/-0.6)sigma. The mass and width of the observed peak are consistent with recent reports of a narrow S=+1 baryon by other experimental groups.     

Eta' photoproduction on the proton for photon energies from 1.527 to 2.227 GeV

Differential cross sections for the reaction gamma p --> eta' p have been measured with the CLAS spectrometer and a tagged photon beam with energies from 1.527 to 2.227 GeV. The results reported here possess much greater accuracy than previous measurements. Analyses of these data suggest for the first time the coupling of the eta'N channel to both the S11(1535) and P11(1710) resonances, known to couple strongly to the etaN channel in photoproduction on the proton, and the importance of J = 3/2 resonances in the process.     

New Measurement of the π0 radiative decay width

High precision measurements of the differential cross sections for π0 photoproduction at forward angles for two nuclei, 12C and 208Pb, have been performed for incident photon energies of 4.9-5.5 GeV to extract the π0→γγ decay width. The experiment was done at Jefferson Lab using the Hall B photon tagger and a high-resolution multichannel calorimeter. The π0→γγ decay width was extracted by fitting the measured cross sections using recently updated theoretical models for the process. The resulting value for the decay width is Γ(π0→γγ)=7.82±0.14(stat)±0.17(syst) eV. With the 2.8% total uncertainty, this result is a factor of 2.5 more precise than the current Particle Data Group average of this fundamental quantity, and it is consistent with current theoretical predictions.     

Eta photoproduction on the proton for photon energies from 0.75 to 1.95 GeV

Differential cross sections for gammap-->etap have been measured with tagged real photons for incident photon energies from 0.75 to 1.95 GeV. Mesons were identified by missing mass reconstruction using kinematical information for protons scattered in the production process. The data provide the first extensive angular distribution measurements for the process above W=1.75 GeV. Comparison with preliminary results from a constituent quark model support the suggestion that a third S11 resonance with mass approximately 1.8 GeV couples to the etaN channel.     

Construction of an infinite-dimensional invariant torus of a countable system of linear differential-difference equations by the method of its reduction in the angular variable

We use the method of reduction in the angular variable to construct an infinite-dimensional invariant torus for a linear system of differential-difference equations that depends on an infinite set of constant deviations of arguments of different signs. This means that the function that defines the torus is represented in the form of the limit of a sequence of functions, each of which defines an invariant torus for the initial system reduced in the angular variable, as the order of reduction tends to infinity.     

Muon Tomography of Large-Scale Objects

Physics of Atomic Nuclei - Cosmic ray muons arriving from the upper hemisphere to the Earth’s surface, are currently used to develop methods of muonography (analogous to radiography) of the...     

CLAS+FROST: new generation of photoproduction experiments at Jefferson Lab.

A large part of the experimental program in Hall B of the Jefferson Lab is dedicated to baryon spectroscopy. Photoproduction experiments are essential part of this program. CEBAF Large Acceptance Spectrometer (CLAS) and availability of circularly and linearly polarized tagged photon beams provide unique conditions for this type of experiments. Recent addition of the Frozen Spin Target (FROST) gives a remarkable opportunity to measure double and triple polarization observables for different pseudo-scalar meson photopro-duction processes. For the first time, a complete or nearly complete experiment becomes possible and will allow model independent extraction of the reaction amplitude. An overview of the experiment and its current status is presented.     

On the existence of invariant tori of countable systems of difference-differential equations defined on infinite-dimensional tori

In the space of bounded number sequences, we establish sufficient conditions for the existence of invariant tori for linear and quasilinear countable systems of differential-difference equations defined on infinitedimensional tori and containing an infinite set of constant deviations of a scalar argument.