High-sensitivity wide-band X-ray spectroscopy is the key feature of the Suzaku X-ray observatory, launched on 2005 July 10. This paper summarizes the spacecraft, in-orbit performance, operations, and data processing that are related to observations. The scientific instruments, the high-throughput X-ray telescopes, X-ray CCD cameras, non-imaging hard X-ray detector are also described.
Measurements of the energy loss of protons and deuterons channeled in a very thin single-crystal foil of gold were performed, covering the range of very low velocities. The experimental results provide clear evidence of the deviation of the energy loss from the proportionality with ion velocity predicted theoretically, showing a transition between two well-defined regimes. We explain this behavior by a theoretical analysis that takes into account the electronic band structure properties of the medium, separating the contribution of the conduction band ͑described as a free Fermi gas͒ from the contribution of the nearly free d electrons of gold, which are affected by a threshold behavior due to the shift of the density of states of this band with respect to the Fermi level. The theoretical model yields a very good description of the experimental findings.
We present a theoretical approach to study the screening charge density n(s)(r) and the respective stopping coefficient Q for hydrogen and helium at the low velocity limit. An electron gas, with electronic density n(e), is used to represent the conduction or valence electrons of the target material. Solving numerically the Schrödinger radial equation, for a given potential V (r), the phase shifts δ(l) and the corresponding stopping coefficient Q are calculated as a function of n(e). The cusp condition and the Friedel sum rule are imposed on the charge density n(r) = n(s)(r)+n(e) at the origin and to the phase shifts, respectively. The results are compared with density functional calculations and with available experimental results.
We have built a detector capable of locating high Z objects in the sampling (middle) region of the detector. As atomic number increases, radiation length rapidly decreases, yielding larger variance in scattering angle. Cosmic ray muon tomography works by tracking muons above the sampling region, and tracking them below the region as well. The difference between the two trajectories yield information, via the muon scattering variance, of the materials contained within the sampling region[1]. One of most important aspects of cosmic ray tomography is minimizing exposure time. The cosmic ray flux is about 1/cm^2/min, and the goal is to use them for detecting high-density materials as quickly as possible. This involves using all of the information possible to reconstruct tracks with redundant detectors. Detector scattering residuals yield a low precision measurement of muon energy. Knowing the rough energy of an incoming particle will yield more precisely the expected scattering variance (currently the expectation value of ~3GeV is used).
The variation of the energy loss versus the exit angle in channeling experiments using H + , He + , and H + fragments produced by the incidence of H 2 + on thin gold crystals oriented in the ͗100͘ direction has been investigated in the low-velocity range, corresponding to energies below 10 keV/ u. The experimental results for H + and He + were compared with computational simulations performed with the MARLOWE code, considering an impact-parameter-dependent energy loss based on electron density calculations and low-energy stopping power models. The comparisons provide information on the impact-parameter dependence of the energy loss for channeled ions and serve as a test of theoretical models in the present low-energy range. A molecular effect is observed for the transmitted H + fragments corresponding to H 2 + incidence. This effect is explained based on geometrical considerations and a vicinage effect in the energy loss of correlated protons.
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