Study of inelastic nuclear interactions of 400 GeV/c protons in bent silicon crystals for beam steering purposes.

Inelastic nuclear interaction probability of 400 GeV/c protons interacting with bent silicon crystals was investigated, in particular for both types of crystals installed at the CERN Large Hadron Collider for beam collimation purposes. In comparison to amorphous scattering interaction, in planar channeling this probability is ∼ 36 % for the quasi-mosaic type (planes (111)), and ∼ 27 % for the strip type (planes (110)). Moreover, the absolute inelastic nuclear interaction probability in the axial channeling orientation, along the ⟨ 110 ⟩ axis, was estimated for the first time, finding a value of 0.6 % for a crystal 2 mm long along the beam direction, with a bending angle of 55 µ rad. This value is more than two times lower with respect to the planar channeling orientation of the same crystal, and increases with the vertical angular misalignment. Finally, the correlation between the inelastic nuclear interaction probability in the planar channeling and the silicon crystal curvature is reported.

Test of "crab-waist" collisions at the DAPhiNE Phi factory.

The electron-positron collider DAPhiNE, the Italian Phi factory, has been recently upgraded in order to implement an innovative collision scheme based on large crossing angle, small beam sizes at the crossing point, and compensation of beam-beam interaction by means of sextupole pairs creating a "crab-waist" configuration in the interaction region. Experimental tests of the novel scheme exhibited an increase by a factor of 3 in the peak luminosity of the collider with respect to the performances reached before the upgrade. In this Letter we present the new collision scheme, discuss its advantages, describe the hardware modifications realized for the upgrade, and report the results of the experimental tests carried out during commissioning of the machine in the new configuration and standard operation for the users.

Constraints on new physics from the quark mixing unitarity triangle.

The status of the unitary triangle beyond the standard model including the most recent results on Deltam[s] on dilepton asymmetries and on width differences is presented. Even allowing for general new physics loop contributions the unitarity triangle must be very close to the standard model result. With the new measurements from the Fermilab Tevatron, we obtain for the first time a significant constraint on new physics in the Bs sector. We present the allowed ranges of new physics contributions to DeltaF=2 processes and of the time-dependent CP asymmetry in Bs-->J/psivarphi decays.

[Breast lymphoma]. / Il linfoma mammario.

Primary malignant lymphomas of the breast are uncommon findings, representing 0.12% to 0.53% of all breast cancers. Secondary lymphomas are also uncommon, but they make the most frequent metastatic breast cancers. From January 1989 through December 1992, at the Department of Radiology of the University of Perugia, the authors observed 6 cases of breast lymphoma--1 primary and 5 secondary lesions--in women 52 to 67 years old (average 60 years). The only primary lymphoma was unilateral, multiple and localized on the right side; the secondary ones were diffuse and bilateral in 4 cases and unilateral and nodular in 1 case. The clinical findings were always suggestive of a malignant lesion and so were the mammographic and US findings in 4 diffuse lesions--3 bilateral and 1 unilateral cancers; in both the primary lymphoma and the secondary nodular lymphoma mammography showed benign patterns. Diagnosis was made in all cases following biopsy or resection of the breast mass; all the lymphomas were of the non-Hodgkin's type. The authors report on the major clinical, mammographic and US features of this unusual disease and include a short review of the relative literature.

CT of ischemic infarctions in the territory of the anterior choroidal artery: a review of 28 cases.

The purpose of the present study was to examine the incidence, causal factors, and anatomic localizations of infarction in the territory of the anterior choroidal artery. We studied 28 patients who had CT evidence of infarction in this territory. The affected structures taken into consideration were the posterior limb of the internal capsule, the retrolenticular portion of the internal capsule, the internal portion of the globus pallidus, and the lateral thalamus. Three conclusions are drawn: that ischemic infarcts in the territory of the anterior choroidal artery are rare, representing 2.9% of all cerebral ischemic lesions in our material; that the incidence of a possible embolic origin is significant; and that the posterior two-thirds of the posterior limb of the internal capsule and the retrolenticular segment are the more frequently affected structures, and conversely, that the medial pallidus and the thalamus are less often involved.