Application of bent crystals at IHEP 70-GeV accelerator to enhance the efficiency of its usage

Bent crystal was extracting 70-GeV protons with average intensity 4*10^11 (as measured in external beamline) per spill of 1.6 s duration, in parallel to the simultaneous work of two internal targets in the accelerator ring. An additional crystal, placed in the external beamline, was deflecting a small part of the extracted beam with intensity 10^7 protons toward another physics experiment. Crystal-extracted beam had a typical size of 4 mm by 4 mm fwhm at the end of the external beamline. Measurements for the extraction efficiency and other characteristics at the simultaneous work of four experimental set-ups are presented. With crystal working in the above-said regime during one month, no degradation of channeling was observed. The studies of extraction efficiency have been continued with new crystals.Comment: 6pp. Presented at EPAC 200

Properties of Neutral Charmed Mesons in Proton--Nucleus Interactions at 70 GeV

The results of treatment of data obtained in the SERP-E-184experiment "Investigation of mechanisms of the production of charmed particles in proton-nucleus interactions at 70 GeV and their decays" by irradiating the active target of the SVD-2 facility consisting of carbon, silicon, and lead plates, are presented. After separating a signal from the two-particle decay of neutral charmed mesons and estimating the cross section for charm production at a threshold energy {\sigma}(c\v{c})=7.1 \pm 2.4(stat.) \pm 1.4(syst.) \mub/nucleon, some properties of D mesons are investigated. These include the dependence of the cross section on the target mass number (its A dependence); the behavior of the differential cross sections d{\sigma}/dpt2 and d{\sigma}/dxF; and the dependence of the parameter {\alpha} on the kinematical variables xF, pt2, and plab. The experimental results in question are compared with predictions obtained on the basis of the FRITIOF7.02 code.Comment: 9 pages, 9 figures,3 table

Observation of narrow baryon resonance decaying into pKs0pK^0_s in pA-interactions at 70GeV/c70 GeV/c with SVD-2 setup

SVD-2 experiment data have been analyzed to search for an exotic baryon state, the $\Theta^+$-baryon, in a $pK^0_s$ decay mode at $70 GeV/c$ on IHEP accelerator. The reaction $pA \to pK^0_s+X$ with a limited multiplicity was used in the analysis. The $pK^0_s$ invariant mass spectrum shows a resonant structure with $M=1526\pm3(stat.)\pm 3(syst.) MeV/c^2$ and $\Gamma < 24 MeV/c^2$. The statistical significance of this peak was estimated to be of $5.6 \sigma$. The mass and width of the resonance is compatible with the recently reported $\Theta^+$- baryon with positive strangeness which was predicted as an exotic pentaquark ($uudd\bar{s}$) baryon state. The total cross section for $\Theta^+$ production in pN-interactions for $X_F\ge 0$ was estimated to be $(30\div120) \mu b$ and no essential deviation from A-dependence for inelastic events $(\sim A^{0.7})$ was found.Comment: 8 pages, 7 figures, To be submitted to Yadernaya Fizika. v3-v5 - Some references added, minor typos correcte

The Evolution of Compact Binary Star Systems

We review the formation and evolution of compact binary stars consisting of white dwarfs (WDs), neutron stars (NSs), and black holes (BHs). Binary NSs and BHs are thought to be the primary astrophysical sources of gravitational waves (GWs) within the frequency band of ground-based detectors, while compact binaries of WDs are important sources of GWs at lower frequencies to be covered by space interferometers (LISA). Major uncertainties in the current understanding of properties of NSs and BHs most relevant to the GW studies are discussed, including the treatment of the natal kicks which compact stellar remnants acquire during the core collapse of massive stars and the common envelope phase of binary evolution. We discuss the coalescence rates of binary NSs and BHs and prospects for their detections, the formation and evolution of binary WDs and their observational manifestations. Special attention is given to AM CVn-stars -- compact binaries in which the Roche lobe is filled by another WD or a low-mass partially degenerate helium-star, as these stars are thought to be the best LISA verification binary GW sources.Comment: 105 pages, 18 figure

The first planet detected in the WTS: an inflated hot Jupiter in a 3.35 d orbit around a late F star

We report the discovery of WTS-1b, the first extrasolar planet found by the WFCAM Transit Survey, which began observations at the 3.8-m United Kingdom Infrared Telescope (UKIRT) in 2007 August. Light curves comprising almost 1200 epochs with a photometric precision of better than 1 per cent to J ˜ 16 were constructed for ˜60 000 stars and searched for periodic transit signals. For one of the most promising transiting candidates, high-resolution spectra taken at the Hobby-Eberly Telescope (HET) allowed us to estimate the spectroscopic parameters of the host star, a late-F main-sequence dwarf (V = 16.13) with possibly slightly subsolar metallicity, and to measure its radial velocity variations. The combined analysis of the light curves and spectroscopic data resulted in an orbital period of the substellar companion of 3.35 d, a planetary mass of 4.01 ± 0.35 MJ and a planetary radius of 1.49-0.18+0.16 RJ. WTS-1b has one of the largest radius anomalies among the known hot Jupiters in the mass range 3-5 MJ. The high irradiation from the host star ranks the planet in the pM class

Connecting Planetary Composition with Formation

The rapid advances in observations of the different populations of exoplanets, the characterization of their host stars and the links to the properties of their planetary systems, the detailed studies of protoplanetary disks, and the experimental study of the interiors and composition of the massive planets in our solar system provide a firm basis for the next big question in planet formation theory. How do the elemental and chemical compositions of planets connect with their formation? The answer to this requires that the various pieces of planet formation theory be linked together in an end-to-end picture that is capable of addressing these large data sets. In this review, we discuss the critical elements of such a picture and how they affect the chemical and elemental make up of forming planets. Important issues here include the initial state of forming and evolving disks, chemical and dust processes within them, the migration of planets and the importance of planet traps, the nature of angular momentum transport processes involving turbulence and/or MHD disk winds, planet formation theory, and advanced treatments of disk astrochemistry. All of these issues affect, and are affected by the chemistry of disks which is driven by X-ray ionization of the host stars. We discuss how these processes lead to a coherent end-to-end model and how this may address the basic question.Comment: Invited review, accepted for publication in the 'Handbook of Exoplanets', eds. H.J. Deeg and J.A. Belmonte, Springer (2018). 46 pages, 10 figure

The Theory of Brown Dwarfs and Extrasolar Giant Planets

Straddling the traditional realms of the planets and the stars, objects below the edge of the main sequence have such unique properties, and are being discovered in such quantities, that one can rightly claim that a new field at the interface of planetary science and and astronomy is being born. In this review, we explore the essential elements of the theory of brown dwarfs and giant planets, as well as of the new spectroscopic classes L and T. To this end, we describe their evolution, spectra, atmospheric compositions, chemistry, physics, and nuclear phases and explain the basic systematics of substellar-mass objects across three orders of magnitude in both mass and age and a factor of 30 in effective temperature. Moreover, we discuss the distinctive features of those extrasolar giant planets that are irradiated by a central primary, in particular their reflection spectra, albedos, and transits. Aspects of the latest theory of Jupiter and Saturn are also presented. Throughout, we highlight the effects of condensates, clouds, molecular abundances, and molecular/atomic opacities in brown dwarf and giant planet atmospheres and summarize the resulting spectral diagnostics. Where possible, the theory is put in its current observational context.Comment: 67 pages (including 36 figures), RMP RevTeX LaTeX, accepted for publication in the Reviews of Modern Physics. 30 figures are color. Most of the figures are in GIF format to reduce the overall size. The full version with figures can also be found at: http://jupiter.as.arizona.edu/~burrows/papers/rm