-------- Original Message -------- Subject: Re: Contract with the CNRS. Date: Mon, 02 Aug 2004 14:17:23 -0400 From: Kevan Hashemi To: Raphael Tieulent CC: Werner Riegler , Jim Bensinger References: <40FFD876.7030800@in2p3.fr> Geometric Monitoring System Specification ----------------------------------------- We discuss the requirements of the GMS, and show how they dictate the technical specifications of the system's components. After our discussion of the requirements, we present a table of technical specifications. System Components ----------------- The ALICE Geometric Monitoring System (GMS) requires optical instruments that cooperate with one another to measure the deformations of a five-meter (5-m) diameter detector structure to a precision of thirty micrometers (30 um). These instruments take several forms, and we shall refer to them collectively as "devices". Electronic circuits, which we shall call "drivers" in the ALICE counting room must supply all power required by the devies, transmit all control signals, and receive all measurements. Space constraints within the ALICE detector require that each device be connected to only one cable, which we shall call a "branch" cable, and that this cable be less than six millimeters (6 mm) in diameter. CERN safety regulations demand that the cable be low-smoke halogen-free. The branch cable must carry power as well as control and measurement signals. Space constraints within the ALICE detector require that up to ten devices share a single cable, which we shall call a "root" cable, from the detector to the ALICE counting room. The ten branch cables of the ten devices must connect to an electronic circuit, which we shall call a "multiplexer", that in turn connects to the counting room drivers via its root cable. The root cable must be low-smoke halogen-free, and no more than six millimeters in diamter (6 mm). The multiplexers receive their own power and selection controls down the root cable. The driver circuits are themselves controlled by a single data acquisition computer (the "master computer") running data acquisition software (the "control program") provided by the manufacturer of the devices, multiplexers, and drivers. The master computer can be controlled with a TCP/IP DIMM interface, and will archive images and measurements for the ALICE slow controls system. The control program includes all image analysis routines required by the devices. The acquisition of images from the devices, and their analysis must proceed at a rate of ten images per second. Devices ------- Devices must operate with full accuracy in up to 10 krad ionizing radiation and 1011 1-MeV eq. n/cm2 neutron radiation. [This is lower than the LWDAQ tolerance of 30 krad and 1012, but ALICE has less radiation.] The orientation and position of each optical device with respect to its mounting fixtures must be known to two hundred microradians (200 urad) and twenty micrometers (20 um) respectively. We must be able to replace any optical device with another of the same type, and know the orientation and position of the new device to the same accuracy without re-measuring the mount or re-calibrating the GMS. The GMS manufacturer must provide step-by-step instructions on how to calibrate each optical device so that it can replace any other optical device of the same type. Any non-standard equipment required by the calibration procedures will be supplied by the manufacturer. The devices must be small so that they will fit into the ALICE detector, and they must be light, so that they do not cause undue scattering of muons. Each device must be less than 500 cc in volume and less than 250 g in mass. Two specific forms of optical instrument are required by ALICE. One monitors the deviation of several points from a straight line, which we shall call the "multi-point monitor". The other monitors the relative movements of two adjacent detector elements, which we shall call the "proximity monitor". The multi-point monitor devices must measure the deviation of a middle device from the straight line between to outer devices to an accuracy of 50 um when the distance between the outer devices is 5 m. The dynamic range of each multi-point device must be at least 10 mrad in each direction from the range center. The proximity monitor must measure the relative displacement of proximity camera and proximity source to 10 um when the two are separated by 50 cm. The dynamic range of each proximity monitor must be at least 10 mm in each direction from the range center. Multiplexers ------------ Multiplexers must operate with full accuracy in up to 10 krad ionizing radiation and 10^11 1-MeV eq. n/cm2 neutron radiation. The must be no larger than 500 cc, preferably smaller, and weigh less than 250 g. Cables ------ The ALICE geometry requires branch cables up to 10 m long. These must obey CERN safety regulations, but also be flexible enough to bend around sharp corners. All signals within the cables must be transmitted as low-voltage differential signals on twisted pairs of wires, and enclosed in a shield. The amplitude of the signal on any wire cannot exceed 0.25 V. A foil shield is sufficient. We specify stranded-core wires for flexibility. The ALICE geometery requires root cables up to 130 m long. These must obey CERN safety regulations. They need not use stranded-core wires, but they must be shielded and transmit low-voltage differential signals in on twisted pairs of wires. Drivers ------- All driver logic must be programmable to allow for future corrections and expansions of data acquisition functions. DAQ Program ----------- All ALICE collaborators, regardless of their personal choice in computers, must be able to run the GMS DAQ Program on a small scale in their laboratories. We require that the DAQ Program be compiled and available for Linux, Windows, and Mac OS X. Intellectual Property --------------------- All drawings, circuit diagrams, printed circuit board layouts, calibration procedures, computer source code, and logic chip source code used in any part of the GMS must be freely distributed by the manufacturing company on electronic media to all ALICE collaborators, without paying any further fees to the manufacturer. Specification ------------- Overall System Accuracy 30 um tracking All Devices: Calibration Accuracy 20 um and 100 urad Ionizing Radiation Tolerance 30 krad Neutron Radiation Tolerance 10^11 1-MeV eq. n/cm^2 Multi-Point Monitor: Max Volume 500 cc Max Mass 250 g Angular Tracking Accuracy < 5 urad Angular Dynamic Range > +-15 mrad in each direction Proximity Monitor: Max Volume 500 cc Max Mass 250 g Position Tracking Accuracy < 20 um Position Dynamic Range > +- 10 mm in each direction Branch Cables: One branch cable per device Stranded-core copper conductors Operate with lengths up to 10 m Conform to CERN fire regulations Max diameter 6 mm Multiplexers: Max Volume 500 cc Max Mass 250 g 8 or more branch cables per multiplexer Ionizing Radiation Tolerance 30 krad Neutron Radiation Tolerance 10^11 1-MeV eq. n/cm^2 Root Cables: One root cable per multiplexer Operate with lengths up to 130 m Conform to CERN fire regulations Max diameter 6 mm Drivers: Supply all power and controls to devices Supply all power and controls to multiplexers Accommodates 8 or more cables Accommodates root or branch cables interchangeably Master Computer Program: Receives instructions over TCP/IP interface Returns data and analysis results over TCP/IP interface Displays live images and anlysis results Runs on Linux, Windows, and Mac OS X All Designs, Schematics, Layouts, Drawings, Artwork, and Software: Freely available to all members of ALICE collaboration