16989103
First test of tiltmeters for the link system of CMS
In this note we present first tests done with the tiltmeters proposed as the key elements of the Laser Level systems to be used in the CMS alignment system. The reponse of the sensors under moderated longitudinal and transversal tilts is studied and intrinsic perform ance is extracted.
123499216
New silicon microstrip detectors optimized for tracker alignment
The resolution of tracking systems based on layers of silicon microstrips is comparable to the stability of the structures on which they are mounted. Environmental changes during operation will misalign the modules out of their nominal positions. A straight laser beam that sequentially traverses consecutive layers of microstrips can be used as an artificial track to align them. For such a laser track to reach the last sensor, high transmittance of microstrips to infrared (IR) light is needed. We have simulated the passage of a coherent beam of light through a microstrip detector and identified the minimum set of changes to the design that boosts its transmittance. The simulation has been validated against real microstrip detector samples.
123257317
PERFORMANCE TEST OF THE CMS LINK ALIGNMENT SYSTEM
Abstract A first global test of the CMS Alignment System was performed at the I4 hall of the CERN ISR tunnel. Positions of the network, reproducing a set of points in the CMS detector monitored by the Link System, were reconstructed and compared to survey measurements. Spatial and angular reconstruction precisions reached in the present experimental set-up are already close to the CMS requirements.
139842026
Test Results of the Semi-transparent Amorphous Silicon Sensors for the Link System of CMS
119795166
2D position sensitive microstrip sensors with charge division along the strip: Studies on the position measurement error
Abstract Position sensitivity in semiconductor detectors of ionizing radiation is usually achieved by the segmentation of the sensing diode junction in many small sensing elements read out separately as in the case of conventional microstrips and pixel detectors. Alternatively, position sensitivity can be obtained by splitting the ionization signal collected by one single electrode amongst more than one readout channel with the ratio of the collected charges depending on the position where the signal was primary generated. Following this later approach, we implemented the charge division method in a conventional microstrip detector to obtain position sensitivity along the strip. We manufactured a proof-of-concept demonstrator where the conventional aluminum electrodes were replaced by slightly resistive electrodes made of strongly doped poly-crystalline silicon and being readout at both strip ends. Here, we partially summarize the laser characterization of this first proof-of-concept demonstrator with special emphasis on the study on how the different noise sources are affecting the device position error along the strip.
122960849
Gamma irradiation of semitransparent amorphous silicon sensors
Abstract Semitransparent amorphous silicon sensors are the key elements for laser light 2D position reconstruction in the CMS alignment system. Some of them have to work in very extreme radiation environment. We have irradiated with gammas, up to 10 MRad, two different sensors and measured their change in performance.
121731391
Revised and extended level scheme of the doubly-odd nucleus 188Ir
High-spin states in the doubly odd $Z=77$ nucleus $^{188}\mathrm{Ir}$ were studied using the reaction $^{186}\mathrm{W}$($^{7}\mathrm{Li}$, $5n$) at 59 MeV and the GASP spectrometer for \ensuremath{\gamma}-ray detection. The level structures recently suggested to be built on the known 4.1(3) ms isomeric state of this nucleus have been considerably revised and extended and an isomer with a lifetime of 17.7(2) ns has been identified within the main decay sequence. In addition two rotational bands built on low spin states below the ms isomer have been observed for the first time. The basic features of the excitation scheme of $^{188}\mathrm{Ir}$ are discussed within the Hartree-Fock-Bogoliubov theory within the Lipkin-Nogami approach with the finite-range density-dependent Gogny force.
17255900
CONSTRAINTS ON A SECOND PLANET IN THE WASP-3 SYSTEM*
There have been previous hints that the transiting planet WASP-3b is accompanied by a second planet in a nearby orbit, based on small deviations from strict periodicity of the observed transits. Here we present 17 precise radial velocity (RV) measurements and 32 transit light curves that were acquired between 2009 and 2011. These data were used to refine the parameters of the host star and transiting planet. This has resulted in reduced uncertainties for the radii and masses of the star and planet. The RV data and the transit times show no evidence for an additional planet in the system. Therefore, we have determined the upper limit on the mass of any hypothetical second planet, as a function of its orbital period.
15140780
Eclipses by circumstellar material in the T Tauri star AA Tau II. Evidence for non-stationary magnetospheric accretion ?
We report the results of a synoptic study of the photometric and spectroscopic variability of the classical T Tauri star AA Tau on timescales ranging from a few hours to several weeks. The AA Tau light curve had been previously shown to vary with a 8.2 d period, exhibiting a roughly constant brightness level, interrupted by quasi-cyclic fading episodes, which we interpreted as recurrent eclipses of the central star by the warped inner edge of its accretion disk (Bouvier et al. 1999). Our observations show the system is dynamic and presents non-stationary variability both in the photometry and spectroscopy. The star exhibits strong emission lines that show substantial variety and variability in their profile shapes and fluxes. Emission lines such as H and H show both infall and outflow signatures and are well reproduced by magnetospheric accretion models with moderate mass accretion rates (10 8 10 9 M yr 1 ) and high inclinations (i 60). The veiling shows variations that indicate the presence of 2 rotationally modulated hot spots corresponding to the two magnetosphere poles. It correlates well with the Hei line flux, with B V and the V excess flux. We have indications of a time delay between the main emission lines (H ,H and Hei) and veiling, the lines formed farther away preceding the veiling changes. The time delay we measure is consistent with accreted material propagating downwards the accretion columns at free fall velocity from a distance of about 8 R?. In addition, we report periodic radial velocity variations of the photospheric spectrum which might point to the existence of a 0.02 M object orbiting the star at a distance of 0.08 AU. During a few days, the eclipses disappeared, the variability of the system was strongly reduced and the line fluxes and veiling severely depressed. We argue that this episode of quiescence corresponds to the temporary disruption of the magnetic con- figuration at the disk inner edge. The smooth radial velocity variations of inflow and outflow diagnostics in the H profile yield further evidence for large scale variations of the magnetic configuration on a timescale of a month. These results may provide the first clear evidence for large scale instabilities developping in T Tauri magnetospheres as the magnetic field lines are twisted by dierential rotation between the star and the inner disk.The interaction between the inner accretion disk and the stellar magnetosphere thus appears to be a highly dynamical and time dependent process.
119545603
Astrometric confirmation of a wide low‐mass companion to the planet host star HD 89744
In our ongoing deep infrared imaging search for faint wide secondaries of planet-candidate host stars we have confirmed astrometrically the companionship of a low-mass object to be co-moving with HD 89744, a companion-candidate suggested already by Wilson et al. (2000). The derivation of the common proper motion of HD 89744 and its companion, which are separated by 62.996±0.035 arcsec, is based on about 5 year epoch difference between 2MASS and our own UKIRT/UFTI images. The companion effective temperature is about 2200K and its mass is in the range between 0.072 and 0.081M⊙, depending on the evolutionary model. Therefore, HD 89744 B is either a very low mass stellar or a heavy brown dwarf companion. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
12971013
Measurement of residual nucleus cross sections and recoil energies in p + Fe collisions at 300, 500, 750, 1000 and 1500 MeV
The production of residual nuclei in p + Fe collisions has been measured at GSI on the FRS facility by means of the reverse kinematic techniques at 300, 500, 750, 1000 and 1500 MeV/A. The cross‐sections larger than 0.01 mb of all isotopes with Z larger than 8 have been obtained. Velocity distributions were also measured. Comparisons to models describing spallation reactions and some empirical formulae often used in astrophysics are presented. These data are directly used to calculate impurety production and DPAs in a thin window as foreseen in spallation sources or accelerator‐driven systems.