Interaction of Strange Particles with Nucleons

title: Inclusive K+-meson production in proton-nucleus interactions
abstract: The production of K+-mesons in pA (A = D, C, Cu, Ag, Au) collisions has been investigated at the COoler SYnchrotron COSY-Jülich for beam energies Tp = 1.0-2.3 GeV. Double differential inclusive pC cross-sections at forward angles ϑ{K^+} < 12° as well as the target mass dependence of the K+ momentum spectra have been measured with the ANKE spectrometer. Far below the free NN threshold at TNN = 1.58 GeV the spectra reveal a high degree of collectivity in the target nucleus. From the target mass dependence of the cross-sections at higher energies, the repulsive in-medium potential of the K+-mesons can be deduced. Using pN cross-section parameterisations from the literature and our measured pD data we derive a cross-section ratio σ(pn↦K+X)/σ(pp↦K+X) ∼ (3-4).

title: Vector and tensor analysing powers in deuteron-proton breakup reactions at intermediate energies
abstract: Vector and tensor analysing powers of the d → p → ( p p ) n (charge-exchange) and d → p → ( p n ) p (non-charge-exchange) breakup reactions have been measured with the ANKE spectrometer at the COSY ring at a deuteron beam energy of 1170 MeV for small momentum transfers to the low excitation energy ( p p ) or ( p n ) systems. A quantitative understanding of the values of A x x and A y y for the charge-exchange reaction is provided by impulse approximation calculations. The data suggest that spin-flip isospin-flip transitions, which dominate the charge-exchange breakup of the deuteron, are also important in the non-charge-exchange reaction.

title: Measurement of Subthreshold K+ Production in pA Collisions with ANKE

title: THE FORWARD DETECTOR OF THE ANKE SPECTROMETER. SCINTILLATION AND CHERENKOV HODOSCOPES
abstract: Central Institute for Nuclear Research, Rossendorf, GermanyThe scintillation and Cherenkov counter system of the forward detector of ANKE, magnetic spec-trometer at the internal beam of the accelerator COSY in Jeulich, is described. The timing and amplitudecharacteristics are presented as well as the capabilities to select physical processes of interest.¶¨¸O¢ ¥E¸O ¸¨¸E¥³ ¸I¨´E¨²²O I¨µ´´OI ¨ I¥·¥´±µ¢¸±¨I ¸I¥EI¨±µ¢ ¶¥·¥¤´¥£µ ¤¥E¥±Eµ· ANKE, ³ £´¨E´µ£µ ¸¶¥±E·µ³¥E· ´ ¢´EE·¥´´¥³ ¶EI±¥ E¸±µ·¨E¥²O COSY ¢ ²¨I¥. ·¨¢¥¤¥´O¨I ¢·¥³¥´´O¥ ¨ ³¶²¨EE¤´O¥ I · ±E¥·¨¸E¨±¨, E ±¦¥ ¢µ§³µ¦´µ¸E¨ ¨I ¶·¨³¥´¥´¨O ¤²O ¢O¤¥²¥´¨O¨´E¥·¥¸EOÐ¨I E¨§¨I¥¸±¨I ¶·µI¥¸¸µ¢.

title: Identification of K+-mesons from subthreshold pA collisions with ANKE at COSY-Jülich
abstract: The spectrometer ANKE has been put into operation at the accelerator COSY of the Forschungszentrum Julich in spring 1998. An initial scientific goal is to study K + -production in pA collisions at subthreshold energies far below the free NN-threshold at T p =1.58 GeV. This requires the identification of K + -mesons in a background of pions and protons, about 10 6 times more intense. In this paper the sophisticated detection system and the software procedures for kaon identification are described. With the help of TOF, energy-loss and range measurements as well as the track information from wire chambers, it is possible to measure d 2 σ/ d Ω d p for deep subthreshold K + production at beam energies down to T p =1.0 GeV.

title: Exoplanets around G-K Giants
abstract: G and K giants are a class of radial velocity (RV) variables. One reason for this variability are planetary companions which are indicated in time series of stellar spectra. Since 2004 these spectra in the visual range were obtained with the high resolution coud\'e \'echelle spectrograph mounted on the 2m telescope of the Th\"uringer Landessternwarte Tautenburg (TLS) for a northern sample of 62 very bright K giants. In the South around 300 G and K giants were observed with HARPS mounted on the 3.6m telescope on La Silla. The TLS sample contains at least 11 stars (18 %) which show low-amplitude, long-period RV variations most likely due to planets. This percentage of planet frequency is confirmed by preliminary results of the HARPS study. Moreover the TLS survey seems to indicate that giant planets do not favour metal-rich stars, are more massive, and have longer periods than those found around solar-type host stars.

title: DETERMINATION OF THE INCLINATION OF THE MULTI-PLANET HOSTING STAR HR 8799 USING ASTEROSEISMOLOGY*
abstract: Direct imaging of the HR 8799 system was a major achievement in the study of exoplanets. HR 8799 is a {gamma} Doradus variable and asteroseismology can provide an independent constraint on the inclination. Using 650 high signal-to-noise, high-resolution, full visual wavelength spectroscopic observations obtained over two weeks at Observatoire de Haute Provence with the SOPHIE spectrograph, we find that the main frequency in the radial velocity data is 1.9875 day{sup -1}. This frequency corresponds to the main frequency as found in previous photometric observations. Using the FAMIAS software to identify the pulsation modes, we find that this frequency is a prograde l = 1 sectoral mode and obtain the constraint that inclination i {approx}> 40{sup 0}.

title: Planetary transit candidates in the CoRoT LRa01 field
abstract: The space mission CoRoT is devoted to the analysis of stellar variability and the photometric detection of extrasolar planets.  We present the list of planetary transit candidates detected in the first short run observed by CoRoT that targeted SRc01, towards the Galactic center in the direction of Aquila, which lasted from April to May 2007.  Among the acquired data, we analyzed those for 1269 sources in the chromatic bands and 5705 in the monochromatic band. Instrumental noise and the stellar variability were treated with several detrending tools, to which several transit-search algorithms were subsequently applied.  Fifty-one sources were classified as planetary transit candidates and 26 were followed up with ground-based observations. Until now, no planet has been detected in the CoRoT data from the SRc01 field.

title: Searching for nuclear stellar discs in simulations of star cluster mergers
abstract: The nuclei of galaxies often host small stellar discs with scalelengths of a few tens of parsecs and luminosities up to 107 L�. To investigate the formation and properties of nuclear stellar discs (NSDs), we look for their presence in a set of N-body simulations studying the dissipationless merging of multiple star clusters in galactic nuclei. A few tens of star clusters with sizes and masses comparable to those of globular clusters observed in the Milky Way are accreted on to a pre-existing nuclear stellar component: either a massive super star cluster or a rapidly rotating, compact disc with a scalelength of a few parsecs, mimicking the variety of observed nuclear structures. Images and kinematic maps of the simulation time-steps are then built and analysed as if they were real and at the distance of the Virgo cluster. We use the Scorza–Bender method to search for the presence of disc structures via photometric decomposition. In one case, the merger remnant has all the observed photometric and kinematic properties of NSDs observed in real galaxies. This shows that current observations are consistent with most of the NSD mass being assembled from the migration and accretion of star clusters into the galactic centre. In the other simulation instead, we detect an elongated structure from the unsharp masked image, that does not develop the photometric or kinematic signature of an NSD. Thus, in the context of searches for a disc structure, the Scorza–Bender method is a robust and necessary tool.