Fracture behaviour of alloys for a new laser ranged satellite

A new laser-ranged satellite called LARES 2 (Laser Relativity Satellite 2) has been recently designed for accurate tests of Einsten's theory of General Relativity and space geodesy. Some high density alloys (8.6-9.3 g/dm3) have been studied and characterised for producing the LARES 2 passive satellite. The considered materials were Copper and Nickel based alloys that have been produced and characterised. Aim of this work was to analyse their fracture behaviour that is a requirement for materials to be used for space applications. Fracture tests have been carried out on several specimens and fracture surfaces have been analysed

Material and surface properties of LARES satellite

LARES (LAser RElativity Satellite) is a passive satellite put in orbit by the VEGA launcher the past 13th of February 2012. It is designed for the accurate test of the Lense-Thirring effect. This phenomenon is induced by the Earth rotation that according to Einstein General Relativity drags space-time and consequently the trajectory of orbiting objects. In order to reach the expected results of few percent accuracy in the measurement of that effect, some restrictive scientfic requirements have been imposed with regard to the material to be used for the satellite body (SB) and to the surface properties of the SB itself, giving special attention to the density of the SB (higher than 17900 kg/m3 ). Furthermore to reduce interaction with the magnetic field of Earth some upper limit to, the electrical conductivity of the alloy was specified. All those aspects along with some considerations on the manufacturing challenges of LARES will be reported. Finally the different methods evaluated for the finishing of the SB, so as to satisfy the scientific requirements such as the infrared emissivity (ε) and the solar absorptivity (α) of the surface will be analysed

Material and manufacturing issues of a laser ranged satellite

contenuti (Abstract) The LARES satellite is an Italian space mission funded by ASI, with CGS as prime contractor and Salento and Sapienza Universities as subcontractors. The LARES will be put into orbit by the European launcher VEGA during its maiden flight, foreseen in year 2011. The paper describes the general features of the material chosen for the manufacturing of the satellite and its components. Particular interest will be devoted to the manufacturing process and analysis of the screw

Fracture behaviour of alloys for a new laser ranged satellite

A new laser-ranged satellite called LARES 2 (Laser Relativity Satellite 2) has been recently designed for accurate tests of Einsten's theory of General Relativity and space geodesy. Some high density alloys (8.6-9.3 g/dm3) have been studied and characterised for producing the LARES 2 passive satellite. The considered materials were Copper and Nickel based alloys that have been produced and characterised. Aim of this work was to analyse their fracture behaviour that is a requirement for materials to be used for space applications. Fracture tests have been carried out on several specimens and fracture surfaces have been analysed

Material and Manufacturing of LARES Satellite

Differently from all other laser ranged satellites, LARES is manufactured from a single piece bulk material. This choice offers a simpler design and will reduce thermal gradients on the satellite surface. To improve the surface-to-mass ratio, i.e., a parameter proportional to the intensity of most of the non gravitational perturbations, a high density material has been selected: tungsten alloy. A combination of data from two more satellites and a design of LARES aimed to reduce the non gravitational perturbations will allow the measurement of the Lense-Thirring effect with an accuracy never reached before. This effect is predicted by Einstein General Relativity. Tungsten alloys have never been used for the entire construction of a satellite. For this reason a first breadboard, representative of a small portion of the satellite has been manufactured. This allowed to pin point a problem with the small screws of the cube corner reflector mounting system. After a description of the material and the procured semi-finished parts, particular interest will be devoted to the manufacturing process for the screws and to the microscopic analysis of the tungsten alloy screws that broke during mounting. A different manufacturing process for the screw is finally proposed

A Novel Approach for an Integrated Straw tube-Microstrip Detector

We report on a novel concept of silicon microstrips and straw tubes detector, where integration is accomplished by a straw module with straws not subjected to mechanical tension in a Rohacell $^{\circledR}$ lattice and carbon fiber reinforced plastic shell. Results on mechanical and test beam performances are reported on as well.Comment: Accepted by Transactions on Nuclear Science (2005). 11 pages, 9 figures, uses lnfprep.st

Novel high-speed monolithic silicon detector for particle physics

This contribution presents simulation results, implementation, and first tests of a monolithic detector developed at KIT. It consists of a sensor diode tightly integrated with an analogue front-end based on SiGe (Silicon-Germanium) SG13G2 130 nm BiCMOS technology produced at the Leibniz Institute for High Performance Microelectronics (IHP). The pixel size is 100 μm × 100 μm, and the nwell charge collection node dimensions were reduced to 10 μm × 10 μm. We investigate the influence of this approach on sensor performance, spatial resolution via charge sharing and timing behaviour

LARES/WEBER-SAT and the equivalence principle

It has often been claimed that the proposed Earth artificial satellite LARES/WEBER-SAT-whose primary goal is, in fact, the measurement of the general relativistic Lense-Thirring effect at a some percent level-would allow to greatly improve, among (many) other things, the present-day (10^-13) level of accuracy in testing the equivalence principle as well. Recent claims point towards even two orders of magnitude better, i.e. 10^-15. In this note we show that such a goal is, in fact, unattainable by many orders of magnitude being, instead, the achievable level of the order of 10^-9.Comment: LaTex, 4 pages, no figures, no tables, 26 references. Proofs corrections included. To appear in EPL (Europhysics Letters

Gas Analysis and Monitoring Systems for the RPC Detector of CMS at LHC

The Resistive Plate Chambers (RPC) detector of the CMS experiment at the LHC proton collider (CERN, Switzerland) will employ an online gas analysis and monitoring system of the freon-based gas mixture used. We give an overview of the CMS RPC gas system, describe the project parameters and first results on gas-chromatograph analysis. Finally, we report on preliminary results for a set of monitor RPC.Comment: 9 pages, 8 figures. Presented by Stefano Bianco (Laboratori Nazionali di Frascati dell'INFN) at the IEEE NSS, San Diego (USA), October 200

The CMS RPC gas gain monitoring system: an overview and preliminary results

The status of the CMS RPC Gas Gain Monitoring (GGM) system developed at the Frascati Laboratory of INFN (Istituto Nazionale di Fisica Nucleare) is reported on. The GGM system is a cosmic ray telescope based on small RPC detectors operated with the same gas mixture used by the CMS RPC system. The GGM gain and efficiency are continuously monitored on-line, thus providing a fast and accurate determination of any shift in working point conditions. The construction details and the first result of GGM commissioning are described.Comment: 8 pages, 9 figures, uses lnfprepCMS.sty, presented by L. Benussi at RPC07, Mumbai, INDIA 200