58925329
Multiwavelength VLBI observations of Sagittarius A
Context. The compact radio, NIR, and X-ray source Sagittarius A* (Sgr A*), associated with the super massive black hole at the center of the Galaxy, has been studied with Very Long Baseline Interferometry (VLBI) observations performed on 10 consecutive days and at mm-wavelength.
118408975
The Arp 220 merger on kpc scales
For the first time, we study the eastern nucleus in greater detail and search for the more extended emission in the molecular gas in different CO line transitions of the famous ultraluminous infrared galaxy (ULIRG) Arp 220. Furthermore, we present a model of the merger in Arp 220 on large scales with the help of the CO data and an optical and near-infrared composite Hubble Space Telescope image of the prototypical ULIRG. Using the Plateau de Bure interferometer (PdBI), we obtained CO (2-1) and (1-0) data at wavelengths of 1 and 3 mm in 1994, 1996, 1997, and 2006 at different beam sizes and spatial resolutions. The simulations of the merger in Arp 220 were performed with the Identikit modeling tool. The model parameters that describe the galaxy merger best give a mass ratio of 1:2 and result in a merger of ~6 × 108 yr. The low-resolution CO (1-0) PdBI observations suggest that there are indications for emission ~10'' toward the south, as well as to the north and to the west of the two nuclei.
17874828
High-frequency VLBI observations of Sgr A* during a multi-frequency campaign in May 2007
In May 2007 the compact radio source Sgr A* was observed in a global multi-frequency monitoring campaign, from radio to X-ray bands. Here we present and discuss first and preliminary results from polarization sensitive VLBA observations, which took place during May 14-25, 2007. Here, Sgr A* was observed in dual polarization on 10 consecutive days at 22, 43, and 86 GHz. We describe the VLBI experiments, our data analysis, monitoring program and show preliminary images obtained at the various frequencies. We discuss the data with special regard also to the short term variability.
18347743
Building CMS pixel barrel detector modules
For the barrel part of the CMS pixel tracker about 800 silicon pixel detector modules are required. The modules are bump bonded, assembled and tested at the Paul Scherrer Institute. This article describes the experience acquired during the assembly of the first ∼200 modules.
119296383
Causality constraints for charged particles
In quantum systems with short-range interactions, causality imposes nontrivial constraints on low-energy scattering parameters. We investigate these causality constraints for systems where a long-range Coulomb potential is present in addition to a short-range interaction. The main result is an upper bound for the Coulomb-modified effective range parameter. We discuss the implications of this bound to the effective field theory for nuclear halo systems. In particular, we consider several examples of proton–nucleus and nucleus–nucleus scattering. For the bound-state regime, we find relations for the asymptotic normalization coefficients (ANCs) of nuclear halo states. As an application of these relations, we extract the ANCs of the excited 2+ and 1− states in 16O from α − 12C scattering data.
119151118
Mechanical design and material budget of the CMS barrel pixel detector
The Compact Muon Solenoid experiment at the Large Hadron Collider at CERN includes a silicon pixel detector as its innermost component. Its main task is the precise reconstruction of charged particles close to the primary interaction vertex. This paper gives an overview of the mechanical requirements and design choices for the barrel pixel detector. The distribution of material in the detector as well as its description in the Monte Carlo simulation are discussed in detail.
119208271
Causality, universality, and effective field theory for van der Waals interactions
We analyze low-energy scattering for arbitrary short-range interactions plus an attractive 1/r^6 tail. We derive the constraints of causality and unitarity and find that the van der Waals length scale dominates over parameters characterizing the short-distance physics of the interaction. This separation of scales suggests a separate universality class for physics characterizing interactions with an attractive 1/r^6 tail. We argue that a similar universality class exists for any attractive potential 1/r^{alpha} for alpha >= 2. We also discuss the extension to multi-channel systems near a magnetic Feshbach resonance. We discuss the implications for effective field theory with attractive singular power law tails.
119283585
Ultraviolet extrapolations in finite oscillator bases
The use of finite harmonic oscillator spaces in many-body calculations introduces both infrared (IR) and ultraviolet (UV) errors. The IR effects are well approximated by imposing a hard-wall boundary condition at a properly identified radius L_eff. We show that duality of the oscillator implies that the UV effects are equally well described by imposing a sharp momentum cutoff at a momentum Lambda_eff complementary to L_eff. By considering two-body systems with separable potentials, we show that the UV energy corrections depend on details of the potential, in contrast to the IR energy corrections, which depend only on the S-matrix. An adaptation of the separable treatment to more general interactions is developed and applied to model potentials as well as to the deuteron with realistic potentials. The previous success with a simple phenomenological form for the UV error is also explained. Possibilities for controlled extrapolations for A > 2 based on scaling arguments are discussed.