Proton source size measurements in the eA-->e'ppX reaction

Two-proton correlations at small relative momentum q were studied in the eA(3He,4He,C,Fe)-->e(')ppX reaction at E(0)=4.46 GeV using the CLAS detector at Jefferson Lab. The enhancement of the correlation function at small q was found to be in accordance with theoretical expectations. Sizes of the emission region were extracted, and proved to be dependent on A and on the proton momentum. The size of the two-proton emission region for He was measured in eA reactions for the first time.     

Electrical transport and magnetic ordering in R 2Ti3Ge4 (R=Dy, Ho and Er) compounds

New R ₂Ti₃Ge₄ (R=Dy, Ho and Er) intermetallic compounds have been synthesized and characterized by X-ray diffraction and low temperature ac magnetic susceptibility, electrical resistivity and thermoelectric power measurements were carried out. The compounds crystallize in the parent, Sm₅Ge₄-type orthorhombic structure (space group Pnma) and lanthanide contraction is observed as one moves along the rare-earth series. The changeover from paramagnetic to antiferromagnetic phase happens at low temperatures and the ordering temperature scales with the de Gennes factor. The electrical resistivity is metallic with a negative curvature above 100 K. Thermopower displays a weak maximum at temperatures less than 50 K signifying the possible phonon and magnon drag effects.     

Elastic properties of the Ta–V system: bcc Ta0.33V0.67 and C15 TaV2

Resonant ultrasound spectroscopy was used to measure the elastic constants of bcc Ta_0.33V_0.67 over the temperature range 3.5–300?K; the results were compared to earlier measurements on C15 TaV₂. The temperature dependence of the polycrystalline shear modulus is completely different in the two phases; that of the bcc phase decreases with temperature whereas that of the C15 phases increases in an anomalous fashion. This difference is consistent with a model involving doubly-degenerate levels at the X point of the Brillouin zone in the C15 phase with the Fermi level lying near the doubly degenerate level. This model accounted for the unusual behaviour of the C15 phase. Debye temperatures were determined from the ultrasonic measurements: 295?K for the C15 phase and 315?K for the bcc phase.     

Measurement of cumulative-photon spectra at high transverse momenta in 12C9Be interactions at an energy of 3.2 GeV per nucleon

For ¹²C⁹Be interactions at a kinetic beam energy of 3.2 GeV per nucleon, the spectra of photons at laboratory angles in the range 55°–73° were measured off the kinematical region available to the interaction of single nucleons within colliding nuclei. The use of a fast trigger for selecting events involving the production of high-transverse-momentum photons made it possible to measure spectra off the kinematical boundary of four-nucleon interaction. It is shown that the proposed procedure is adequate to the problem of searches for and investigation of flucton-flucton interaction. In the kinematical region where flucton-flucton interaction can manifest itself, the cross sections in question are on the same order of magnitude as respective model predictions. In order to draw definitive conclusions on the role of flucton-flucton interaction, it is highly desirable to extend the angular range of the measurements toward smaller angles.     

Source-size measurements in the e3He(4He) → e′pΛX reaction

We report preliminary data on proton-lambda correlations at small relative momentum q in the e ³He(⁴He) → e′pΛX reaction at E ₀ = 4.7(4.46) GeV using the CLAS detector at Jefferson Lab. The enhancement of the correlation function at small q was found to be in qualitative agreement with theoretical expectations. The size of emission region about 1.5 fm was estimated using Lednicky-Lyuboshitz analytical model. The experimental correlation function is comparable with the P-matrix fit of the hyperon-nucleon data. Small-relative-momentum-proton-lambda correlations both for ³He(⁴He) target and for electroproduction reaction were studied for the first time. (for CLAS Collaboration) The text was submitted by the authors in English.     

The dependence of proton correlations on integral characteristics of eA interactions

We report the results of analysis of correlations of the product protons from inelastic eA collisions at smallQ ². The experimental data were measured by the ARGUS detector. The correlation effect at small relative momentaq (interference and final state interaction) is closely associated with the angular correlations due to momentum conservation. The examined correlations in eA collisions also show features similar to correlations in hA collisions.     

Proton-pion and two- pion correlations in eA interactions

We report here the results on studying of proton-pion and two-pion correlations in eA interactions at 5 GeV. Kinematic correlations were studied as a function of the two-particle opening angle, their momenta and proton multiplicity. The universal properties of correlation functions were found with respect to different particle species. Interferometry method was used to determine the size of the interaction region.