A portable Compton spectrometer for clinical X-ray beams in the energy range 20-150 keV

Primary beam spectra were obtained for an X-ray industrial equipment (40-150 kV), and for a clinical mammography apparatus (25-35 kV) from beams scattered at angles close to 90 degrees, measured with a CdTe Compton spectrometer. Actual scattering angles were determined from the Compton energy shift of characteristic X-rays or spectra end-point energy. Evaluated contribution of coherent scattering amounts to more than 15% of fluence in mammographic beams. This technique can be used in clinical environments. (C) 2010 Elsevier Ltd. All rights reserved.

Robustness of bipartite Gaussian entangled beams propagating in lossy channels

Subtle quantum properties offer exciting new prospects in optical communications. For example, quantum entanglement enables the secure exchange of cryptographic keys(1) and the distribution of quantum information by teleportation(2,3). Entangled bright beams of light are increasingly appealing for such tasks, because they enable the use of well-established classical communications techniques(4). However, quantum resources are fragile and are subject to decoherence by interaction with the environment. The unavoidable losses in the communication channel can lead to a complete destruction of entanglement(5-8), limiting the application of these states to quantum-communication protocols. We investigate the conditions under which this phenomenon takes place for the simplest case of two light beams, and analyse characteristics of states which are robust against losses. Our study sheds new light on the intriguing properties of quantum entanglement and how they may be harnessed for future applications.

Single-step chemical synthesis of ferrite hollow nanospheres

We report a single-step chemical synthesis of iron oxide hollow nanospheres with 9.3 nm in diameter. The sample presents a narrow particle diameter distribution and chemical homogeneity. The hollow nature of the particles is confirmed by HRTEM and HAADF STEM analysis. Electron and x-ray diffraction show that the outer material component is constituted by 2 nm ferrite crystals. Mossbauer data provide further evidence for the formation of iron oxide with high structural disorder, magnetically ordered at 4.2 K and superparamagnetism at room temperature. An unusual magnetic behavior under an applied field is reported, which can be explained by the large fraction of atoms existing at both inner and outer surfaces.

Scientific program of the Radioactive Ion Beams Facility in Brasil (RIBRAS)

The RIBRAS facility (Radioactive Ion Beams in Brasil) is installed in connection with the 8MV Pelletron tandem of the University of Sao Paulo Physics Institute. It consists of two superconducting solenoids which focalize light radioactive secondary beams of low energy, produced by transfer reactions. Recent experimental results include the elastic scattering and transfer reactions of (6)He halo nucleus on (9)Be, (27)Al, (51)V and (120)Sn targets. The elastic scattering and transfer of (8)Li and (7)Be on several targets is also being studied. The transfer reaction (8)Li(p,alpha)(5)He of astrophysical interest was also Studied in the E(cm)=0.2-2.5 MeV energy range.