Electronic Raman scattering of Tl-2223 and the symmetry of the supercon- ducting gap

Single crystalline Tl2Ba2Ca2Cu3O10 was studied using electronic Raman scattering. The renormalization of the scattering continuum was investigated as a function of the scattering geometry to determine the superconducting energy gap 2Delta(k). The A1g- and B2g-symmetry component show a linear frequency behaviour of the scattering intensity with a peak related to the energy gap, while the B1g-symmetry component shows a characteristic behaviour at higher frequencies. The observed frequency dependencies are consistent with a dx^2-y^2-wave symmetry of the gap and yield a ratio of 2Delta/k_BT_c=7.4. With the polarization of the scattered and incident light either parallel or perpendicular to the CuO2-planes a strong anisotropy due to the layered structure was detected, which indicates an almost 2 dimensional behaviour of this system.Comment: 2 pages, Postscript-file including 2 figures. Accepted for publication in the Proceedings of the M^2SHTSC IV Conference, Grenoble (France), 5-9 July 1994. Proceedings to be published in Physica C. Contact address: [email protected]

Experimental investigations of synchrotron radiation at the onset of the quantum regime

The classical description of synchrotron radiation fails at large Lorentz factors, $\gamma$, for relativistic electrons crossing strong transverse magnetic fields $B$. In the rest frame of the electron this field is comparable to the so-called critical field $B_0 = 4.414\cdot10^9$ T. For $\chi = \gamma B/B_0 \simeq 1$ quantum corrections are essential for the description of synchrotron radiation to conserve energy. With electrons of energies 10-150 GeV penetrating a germanium single crystal along the $$ axis, we have experimentally investigated the transition from the regime where classical synchrotron radiation is an adequate description, to the regime where the emission drastically changes character; not only in magnitude, but also in spectral shape. The spectrum can only be described by quantum synchrotron radiation formulas. Apart from being a test of strong-field quantum electrodynamics, the experimental results are also relevant for the design of future linear colliders where beamstrahlung - a closely related process - may limit the achievable luminosity.Comment: 11 pages, 18 figures, submitted to PR

Extraskeletal Osteosarcoma of the Mandibular Salivary Gland in a Dog

Abstract. A 14-year-old spayed female shepherd/collie crossbred dog had a 6 ϫ 4-cm mass excised from below the right ear. The partially encapsulated, neoplastic mass had a necrotic core and was embedded in the mandibular salivary gland. Histologically, the mass was composed of numerous multinucleate giant cells and large, oval, pleomorphic cells that produced osteoid. Neoplastic cells were immunoreactive for vimentin and actin but not for keratin, desmin, or S-100 protein. At postmortem examination 1 month later, an 11-cm spherical mass had recurred at the surgical site, and there were metastatic nodules in the lungs, ipsilateral mandibular lymph nodes, and kidney. The tumor was diagnosed as an osteosarcoma of the mandibular salivary gland with pulmonary, lymphatic, and renal metastasis. In addition, a 17-year survey of canine salivary-gland neoplasms revealed that most were adenocarcinomas or carcinomas