117310029
Simulation of LiCAS Error Propagation
Linear Collider Alignment and Survey (LiCAS) R&D group is proposing a novel automated metrology instrument dedicated to align and monitor the mechanical stability of a future linear high energy e + e collider. LiCAS uses Laser Straightness Monitors (LSM) and Frequency Scanning Interferometry (FSI) [2, 3] for straightness and absolute distance measurements, respectively. This paper presents detailed simulations of a LiCAS system operating inside a Rapid Tunnel Reference Surveyor (RTRS train). With the proposed design it is feasible to achieve the required vertical accuracy of the order of O(200)µm over 600m tunnel sections meeting the specification for the TESLA collider [4]. 1 Principle of the LICAS-RTRS train operation In figure 1 the schematic view of the LiCAS train operating in the accelerator tunnel is presented. The train is composed of 6 cars, the distance between the centres of neighbouring cars is � 4.5m. Each car is equipped with 4 CCD cameras and two beam splitters (BS) constituting the straightness monitor. The straightness monitor measures the transverse translation (Tx,Ty) and transverse rotation (Rx,Ry) with respect to a z axis defined by the laser beam passing through all cars in a vacuum pipe. The laser beam is reflected back using the retro-reflector (RR) located in the last car, illuminating the upper CCD cameras of the straightness monitors. 6 FSI lines placed in the same vacuum pipe between each pair of cars are responsible for the distance measurement along the z axis (Tz). In addition a clinometer located on each car provides a measurement of rotation around the z axis (Rz). When the train stops in front of the wall markers it firstly measures the relative position and rotation of all cars with respect to the first car. This defines the local reference frame of the train in which the location of the wall mounted reference markers are measured next. This procedure is repeated for each train stop. Each marker is measured up to 6 times. Finally the coordinates of each marker, expressed in the local train frames are transformed to the frame of the first train (the global frame) by fitting them to each other under the constraint that wall markers have not moved during the entire measurement. 2 Opto-geometrical model of the LICAS-RTRS train In order to study the expected precision on the position reconstruction of the tunnel reference markers a simulation of the LiCAS survey train was performed. To describe the sensing parts of the train the Simulgeo [5] package was used which allows for modelling
54789766
CONTROL OF THE GEOMETRICAL CONFORMITY OF THE LHC INSTALLATION WITH A SINGLE LASER SOURCE
A large and complex accelerator like LHC machine needs to integrate several thousand different components in a relatively limited space. During the installation, those components are installed in successive phases, always aiming to leave the necessary space available for the equipment which will follow. To help ensure the correct conditions for the installation, the survey team uses a laser scanner to measure specific areas and provides this data, merged together in a known reference system, to the integration team who compare the results with the 3D CAD models. This paper describes the tools and software used to rebuild underground zones in the CATIA environment, to check interferences or geometrical non conformities, as well as the procedures defined to solve the identified problems.
55746504
The versatile link, a common project for super-LHC
A common project to develop a bi-directional, radiation tolerant, high speed (4.8 Gb/s) optical link for future high energy physics experiments is described. Due to be completed in 2012, it targets the upgrade programs of detectors installed at CERN's Large Hadron Collider (LHC). The development of radiation and magnetic field tolerant opto-electronic devices, fibre and connectors is described. Both Single-Mode and Multi-Mode versions of the system operating respectively at 850 nm and 1310 nm wavelength are proposed. First results at component and system level are presented, based mostly on commercially available devices.
145877714
The LiCAS-RTRS - A Rapid and Cost Efficient Survey System for the ILC
A vertically stored can dispenser having the capability to retain multiple size food cans and provide easy access to the various size can channels. The dispenser can be attached to a lazy susan rotary base or attached to a slide-out cabinet dispenser device. The multiple size can channels can be interchanged.
121659740
The CDF level 2 calorimetric trigger upgrade
Abstract CDF II upgraded the calorimeter trigger to cope with the higher detector occupancy due to the increased Tevatron instantaneous luminosity ( ∼ 2.8 × 10 32 cm - 2 s - 1 ) . While the original system was implemented in custom hardware and provided to the L2 trigger a limited-quality jet clustering performed using a reduced resolution measurement of the transverse energy in the calorimeter trigger towers, the upgraded system provides offline-quality jet reconstruction of the full resolution calorimeter data. This allows to keep better under control the dependence of the trigger rates on the instantaneous luminosity and to improve the efficiency and purity of the trigger selections. The upgraded calorimeter trigger uses the general purpose VME board Pulsar, developed at CDF II and already widely used to upgrade the L2 tracking and L2 decision systems. A battery of Pulsars is used to merge and send the calorimeter data to the L2 CPUs, where software-implemented algorithms perform offline-like clustering. In this paper we review the design and the performance of the upgraded system.
204013563
KEKB beam collision stability at the picosecond timing and micron position resolution as observed with the Belle detector
Using the Belle detector we study the characteristics of beam collisions at the KEKB 3.5 GeV e+ on 8 GeV e− asymmetric energy collider. We investigate the collision timing tIP and its z-coordinate along the beam axis zIP as a function of the position of the colliding bunch in a beam train. The various tIP and zIP behaviors observed by Belle are attributed to beam loading effects in the radio frequency cavities that accelerate the beams with a beam abort gap. We report these results in detail and discuss the prospects for the SuperKEKB collider.
54051753
New Measurements of Upsilon Spin Alignment at the Tevatron
We describe a new analysis of {Upsilon}(nS) {yields} {mu}{sup +}{mu}{sup -} decays collected in p{bar p} collisions with the CDF II detector at the Fermilab Tevatron. This analysis measures the angular distributions of the final state muons in the {Upsilon} rest frame, providing new information about {Upsilon} production polarization. We find the angular distributions to be nearly isotropic up to {Upsilon} p{sub T} of 40 GeV/c, consistent with previous measurements by CDF, but inconsistent with results obtained by the D0 experiment. The results are compared with recent NLO calculations based on color-singlet matrix elements and non-relativistic QCD with color-octet matrix elements.
117932304
Tevatron bunch length studies at CDF
A luminous interaction region can be described by the distribution in (x, y, z) over which p{bar p} interactions are observed in a detector. The spatial size of this distribution can be written in terms of expressions that involve only combinations of the proton and anti-proton bunch sizes. Hence, it is not possible to determine the sizes of the proton and anti-proton bunches independently by fitting the distribution of (x, y, z) from the recorded events. If, in addition to the coordinates (x, y, z) at which p{bar p} interactions occur, the times at which the interactions took place are also measured, then it becomes possible to measure the lengths of the proton and anti-proton bunches separately. This sensitivity is due to a correlation between z and t that arises from the fact that the proton and anti-proton bunches travel in opposite directions. The derivation presented in section 2 quantifies this correlation, resulting in an expression for the probability density as a function of z and t for p{bar p} interactions. By fitting the distributions observed at CDF using this model, we measure the lengths of the proton and anti-proton bunches at times throughout several Tevatron stores. From this analysismore » the evolution of the bunch lengths can be studied. We attempt to correlate these with other measures of the bunch length obtained using different experimental techniques.« less
116922520
Measurement of Pion Transparency in Nuclei
We propose to measure pion electroproduction off {sup 1}H, {sup 2}, {sup 12}C, {sup 64}Cu, and {sup 197}Au, and extract the pion transparency through the nuclear medium between Q{sup 2} = 1 and 5 (GeV/c){sup 2}. The pion transparency is predicted to be a signature of the onset of nuclear filtering and/or Color Transparency. Recent experiments have reported evidence for Color Transparency effects at Q{sup 2} approx 10 (GeV/c){sup 2}. The occurrence of nuclear filtering could potentially explain the apparent discrepancy between (proton) nuclear transparencies found in quasielastic A(e,e'p) and A(p,2p) experiments. The occurrence of these effects is an effective signature of the approach to the factorization regime in meson electroproduction experiments, necessary for the access to Generalized Parton Distributions. Measurable effects of approx. 40% are predicted for this region of Q{sup 2}. The proposed experiment seeks to measure the pion transparency with 5-10% uncertainties, dominated by systematics, up to Q{sup 2} = 5 (GeV/c){sup 2}.