The supernova remnant (SNR) RX J0852.0-4622 (Vela Jr., G266.6-1.2) is one of the most important SNRs for investigating the acceleration of multi-TeV particles and the origin of Galactic cosmic rays ...because of its strong synchrotron X-ray and TeV γ-ray emission, which show a shell-like morphology similar to each other. Using the XMM-Newton archival data consisting of multiple pointing observations of the northwestern rim of the remnant, we investigate the spatial properties of the nonthermal X-ray emission as a function of distance from an outer shock wave. All X-ray spectra are well reproduced by an absorbed power-law model above 2 keV. It is found that the spectra show gradual softening from a photon index Γ = 2.56 in the rim region to Γ = 2.96 in the interior region. We show that this radial profile can be interpreted as a gradual decrease of the cutoff energy of the electron spectrum due to synchrotron cooling. By using a simple spectral evolution model that includes continuous synchrotron losses, the spectral softening can be reproduced with the magnetic field strength in the post-shock flow to less than several tens of μG. If this is a typical magnetic field in the SNR shell, γ-ray emission would be accounted for by inverse Compton scattering of high-energy electrons that also produce the synchrotron X-ray emission. Future hard X-ray imaging observations with Nustar and ASTRO-H and TeV γ-ray observations with the Cherenkov Telescope Array (CTA) will allow us to explore other possible explanations of the systematic softening of the X-ray spectra.
This paper describes the recent development of a gigabit data transmitter for the Belle-II pixel detector (PXD). The PXD is an innermost detector currently under development for the upgraded KEK-B ...factory in Japan. The PXD consists of two layers of DEPFET sensor modules located at 1.8 and 2.2 cm radii. Each module is equipped with three different ASIC types mounted on the detector substrate with a flip-chip technique: (a) SWITCHER for generating steering signals for the DEPFET sensors, (b) DCD for digitizing the signal currents, and (c) DHP for performing data processing and sending the data off the module to the back-end data handling hybrid via similar to 40cm Kapton flex and 12-15 m twisted pair (TWP) cables. To meet the requirements of the PXD data transmission, a prototype of the DHP data transmitter has been developed in a 65-nm standard CMOS technology. The transmitter test chip consists of current-mode logic (CML) drivers and a phase-locked loop (PLL) which generates a clock signal for a 1.6 Gbit/s output data stream from an 80 cm reference clock. A programmable pre-emphasis circuit is also implemented in the CML driver to compensate signal losses in the long cable by shaping the transmitted pulse response. The jitter performance was measured as 25 ps (1 sigma 1 sigma distribution) by connecting the chip with 38 cm flex and 10 m TWP cables.
The hard X-ray detector (HXD-II) is one of the three scientific instruments onboard Japanese X-ray astronomy satellite Astro-E2 scheduled to be launched in 2005. This mission is very unique in a ...point of having a lower background than any other past missions in the 10-600 keV range. In the HXD-II, the large and thick BGO crystals are used as active shields for particle and gamma-ray background to the main detector. They have a wide field of view of ~2pi and a large effective area of 400 cm 2 even at 1 MeV. Hence, the BGO shields have been developed as a wide-band all-sky monitor (WAM) with a broadband coverage of 50-5000 keV. In this paper, overall design and performance of the HXD-II/WAM based on the results of preflight calibration tests carried out in June 2004 are described. By irradiating various radio isotopes with the WAM flight model, we verified that it had comparable capabilities with other gamma-ray burst detectors
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