X-ray morphologies of Abell clusters Mcmillan, S. L. W.; Kowalski, M. P.; Ulmer, M. P.
The Astrophysical journal. Supplement series,
08/1989, Letnik:
70, Številka:
4
Journal Article
Recenzirano
Results are presented for X-ray measurements made with the Einstein Observatory's IPC for a sample of 49 Abell clusters, which were used to determine quantitative measures of two morphological ...parameters of these clusters, the orientation and ellipticity. Consideration is given to the techniques used for estimating and removing background noise in the images and for determining the variation of these parameters with the flux level of a cluster. It was found that most clusters are clearly flattened; for 20 of these clusters, the orientation was unambiguously determined. A catalog of cluster properties is presented.
We determine the relative branching fractions of semileptonic B decays to charmed final states. The measurement is performed on the recoil from a fully reconstructed B meson in a sample of 362 × 10 6 ...B ¯¯¯ B pairs collected at the Υ ( 4 S ) resonance with the BABAR detector. A simultaneous fit to a set of discriminating variables is performed on a sample of ¯¯¯ B → D X ℓ − ¯ ν ℓ decays to determine the contributions from the different channels. We measure Γ ( B − → D ℓ − ¯ ν ℓ ) / Γ ( B − → D X ℓ − ¯ ν ℓ ) = 0.227 ± 0.014 ± 0.016 , Γ ( B − → D ∗ ℓ − ¯ ν ℓ ) / Γ ( B − → D X ℓ − ¯ ν ℓ ) = 0.582 ± 0.018 ± 0.030 , and Γ ( B − → D ** ℓ − ¯ ν ℓ ) / Γ ( B − → D X ℓ − ¯ ν ℓ ) = 0.191 ± 0.013 ± 0.019 for the charged B sample, and Γ ( ¯¯¯¯¯ B 0 → D ℓ − ¯ ν ℓ ) / Γ ( ¯¯¯¯¯ B 0 → D X ℓ − ¯ ν ℓ ) = 0.215 ± 0.016 ± 0.013 , Γ ( ¯¯¯¯¯ B 0 → D ∗ ℓ − ¯ ν ℓ ) / Γ ( ¯¯¯¯¯ B 0 → D X ℓ − ¯ ν ℓ ) = 0.537 ± 0.031 ± 0.036 , and Γ ( ¯¯¯¯¯ B 0 → D ** ℓ − ¯ ν ℓ ) / Γ ( ¯¯¯¯¯ B 0 → D X ℓ − ¯ ν ℓ ) = 0.248 ± 0.032 ± 0.030 for the neutral B sample, where uncertainties are statistical and systematic, respectively.
Millimeter wave wireless communications are opening the way towards high data rate applications for WPAN scenarios. Multi-Gbps wireless systems are currently defined by standardization bodies. This ...paper presents a complete 60 GHz OFDM PHY layer proposal fulfilling the requirements of the IEEE 802.15 Task Group 3c. Data rates are ranging from 335 Mbps to 3 Gbps, with a high level of scalability. The proposed system is designed to operate in the 57 to 66 GHz frequency band, with a possibility to use channel sizes of 1 GHz and 2 GHz. The OFDM PHY layer allows scalable spectrum efficiency to achieve high data rates with flexible radio coverage. For a nominal channel bandwidth of 1 GHz, the system uses an FFT size of 1024, convolutional coding and advanced interleaving schemes. Simulation results show that this system is well suited for very high data rate applications in realistic scenarios.
We study the decays B0 to J/psi pi+pi- and B+ to J/psi pi+pi0, including intermediate resonances, using a sample of 382 million BBbar pairs recorded by the BaBar detector at the PEP-II e+e- B ...factory. We measure the branching fractions B(B0 ->J/psi rho0) = (2.7 +/- 0.3 +/- 0.17) x 10-5 and B(B+ ->J/psi rho+) = (5.0 +/- 0.7 +/-0.31) x 10-5. We also set the following upper limits at the 90% confidence level: B(B0 -> J/psi pi+ \pi- non-resonant) < 1.2 x 10-5, B(B0 -> J/psi f_2(1270)) < 4.6 x 10-6, and B(B+ -> J/psi pi+ pi0 non-resonant) < 4.4 x 10-6. We measure the charge asymmetry in charged B decays to J/psi rho to be -0.11 +/- 0.12 +/- 0.08.
We present the design and characterisation of a cryogenic window based on an ultra-thin aluminised PET foil at T < 10K, which can withstand a pressure difference larger than 1bar at a leak rate < ...\(1\times 10^{-9}\) mbar\(\cdot\) l/s. Its thickness of approximately 1.7 \(\mu\)m makes it transparent to various types of particles over a broad energy range. To optimise the transfer of 100keV antiprotons through the window, we tested the degrading properties of different aluminium coated PET foils of thicknesses between 900nm and 2160nm, concluding that 1760nm foil decelerates antiprotons to an average energy of 5 keV. We have also explicitly studied the permeation as a function of coating thickness and temperature, and have performed extensive thermal and mechanical endurance and stress tests. Our final design integrated into the experiment has an effective open surface consisting of 7 holes with 1 mm diameter and will transmit up to 2.5% of the injected 100keV antiproton beam delivered by the AD/ELENA-facility of CERN.
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