120064071
Semitransparent amorphous silicon sensors for the CMS alignment: an in-depth study
Abstract Semitransparent amorphous silicon sensors have been proposed as the 2D positioning sensors for the link system of the CMS alignment. An in-depth study of the actual performance of these sensors is here reported.
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.
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.
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.
125314523
PROPOSAL FOR A TEST OF AN IMPACT PARAMETER TRIGGER AIMED AT A HIGH STATISTICS HEAVY QUARK STUDY
139842026
Test Results of the Semi-transparent Amorphous Silicon Sensors for the Link System of CMS
118472064
Coordinated Multiwavelength Observations of V410Tau
In November 2001 we undertook a coordinated observing campaign to study the connection between X-ray and optical variability in the weak-line T Tauri star V410Tau. The observing plan included three 15 ksec observations with Chandra using the Advanced CCD Imaging Spectrometer for Spectroscopy scheduled for different phases of the known 1.87 d starspot cycle. Photometric and spectroscopic monitoring of V410Tau involving telescopes on three different continents was scheduled simultaneously with the Chandra exposures.
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.
118504351
Multi-wavelength study of the disk around the very low-mass star Par-Lup3-4
Context. Par-Lup3-4 is a very low-mass star (spectral type M5) in the Lupus III star-forming region. It shows spectroscopic evidence of accretion and mass-loss. In the optical and near-infrared, the object is underluminous by ≈4 mag when compared to objects of similar mass in the same association. Aims. The aim of this work is to characterize the circumstellar environment of Par-Lup3-4 to better understand the origin of its underluminosity. Methods. We have analyzed high angular resolution near-IR observations and searched for extended emission from a disk and/or an envelope. We have studied the spectral energy distribution (SED) of the target from the optical to the sub-millimeter regime, and compared it to a grid of radiative transfer models of circumstellar disks. Since the target is strongly variable, we modeled two different near-infrared datasets. Results. The SED of Par-Lup3-4 resembles that of objects with edge-on disks seen in scattered light, that is, a double peaked-SED and a dip at ∼10 μm. The diffraction-limited infrared observations do not show obvious extended emission, allowing us to put an upper limit of ∼20 AU to the disk outer radius. Par-Lup3-4 is probably in a Class II (rather than a Class I) evolutionary stage, which is indicated by the lack of extended emission together with the non detection of a strong 9.8 μm silicate in absorption. This last feature is indeed seen in emission. We fitted the whole SED of Par-Lup3-4 with a single disk model. Our modeling predicts a disk inclination of 81 ◦ ± 6 ◦ , which agrees well with previous estimates, and provides a natural explanation for the under-luminosity of the target. The detection of the silicate feature in emission at such a high inclination might be related to a more complex disk structure (e.g. asymmetries, inhomogeneities) than the one assumed here. Our analysis allows us to put constraints on the disk inner radius, Rin ≤ 0.05 AU, which is very close to the dust sublimation radius, and the maximum size of the dust grains, amax ≥ 10 μm, which indicates that dust processing has already taken place in Par-Lup3-4. Some of the derived disk parameters vary depending on the modeled near-infrared data-set, which emphasizes the importance of taking variability into account when modeling the SED of young stellar objects.
121953438
Bosonic string theory in Lorentzian principal circle bundles over anti-de-Sitter space AdS3
Abstract In this note we show a bosonic conformal string theory on U (1)-bundles over AdS 3 . To this end, we first look for r -elastic helices in the space AdS 3 , because they generate solutions of the motion equation on backgrounds P which are principal circle-bundles over AdS 3 endowed with the standard metric or generalized Kaluza–Klein metrics. In fact, we reduce the search of U (1)-symmetric string configurations on P to the search of r -elastic curves in the orbit space AdS 3 .
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.