Angular-resolved electron spectroscopy from (110) surfaces of ternary Ce-based intermetallics: CePd2Si2 and CeNi2Ge2

Investigations of electronic properties were carried out for the ternary Ce-based intermetallic systems CeT2X2 (T = Ni, Pd; X = Ge, Si). To produce well-ordered and atomically clean surfaces, preparation is carried out in UHV. The polycrystalline substance was evaporated on a W(110) substrate with subsequent annealing. The single-crystalline layers obtained are characterised by MEED (thickness), AES (surface stoichiometry), LEED and SEM (surface structure). For electron-spectroscopic investigations, ARUPS (angle-resolved photoemission spectroscopy) was used. In the photoemission spectra, dispersion effects could be detected by variation of the detection angle.

Response of BGO detectors to photons of 3–50 MeV energy

Abstract The response of an array of 7 hexagonal BGO detectors each 7.5 cm long (6.7 radiation lengths) with 3.6 cm side-to-side distance was measured using monochromatic photons from the tagged-photon facility at the electron accelerator MAMI A at Mainz. The experimental spectra of the deposited energy for a single detector and for the array of seven modules compare very well with the predictions of Monte Carlo shower simulations using the code GEANT3. Significant improvement of the energy resolution is observed for the summed energy spectra compared to the resolution of a single module. This improvement deteriorates at higher photon energies because the length of the detector is not suffi…

k-resolved electronic properties of ternary heavy fermion systems

Electron-spectroscopic investigations on ternary HFS: CeT2X2

Investigations of the electronic properties were carried out for ternary Ce-based heavy fermion systems. The well-ordered surfaces of HFS were prepared by MBE on W (110) with subsequent annealing. The layers are characterised by MEED, LEED, AES and XPS. For the electron-spectroscopic investigations, ARUPS and SPEELS were used. In the photoemission spectra, dispersion effects could be detected. By means of SPEELS, the dipole-forbidden Ce f-f transitions could be observed. The comparison of the energy loss spectra above and below the characteristic temperature T∗ reveals differences in the energy losses as well as in the asymmetries.