Grounding, Power Distribution And New Readout Technologies Excerpts from: US ATLAS Upgrade Workshop 6/7-Jan-2004 SCIPP Seminar 12-Jan-04 Alex Grillo SCIPP - UCSC 12-Jan-2003 1 Grounding, Power Distribution and New Readout Technologies

Grounding, Power Distribution and New Readout Technologies The ATLAS Detector Largest HEP Apparatus ever built - A general purpose particle spectrometer One of four LHC detectors The Inner Detector ATLAS eTour at http://atlasexperiment.org/ 12-Jan-2003 2 Grounding, Power Distribution and New Readout Technologies

ID Grounding Principles Sub-detectors are electrically independent (floating power supplies) except for connections to IDGND, the global ID reference point. All connections to IDGND from sub-detectors are from the EM shields surrounding the detector sections. Analogue and digital ground referenced on detector modules Module ground connected to the individual EM shield. 12-Jan-2003 3 Grounding, Power Distribution and New Readout Technologies

SCT Grounding Layout for Example 12-Jan-2003 4 Grounding, Power Distribution and New Readout Technologies

SCT Power Distribution for Example 12-Jan-2003 5 Grounding, Power Distribution and New Readout Technologies

Driving Issues for Grounding Scheme The grounding scheme keeps a single point ground at the detector and allows the floating power supplies and cable plant to be distributed over a wide area, stretching to USA15 and US15 on either side of the collider hall, without introducing any loops. For the SCT and Pixels, the control signals to the detector and the data signals from the detector are optical eliminating any electrical interconnects between the Off-Detector DAQ system and the detector. To minimize any electrical interference between other monitoring systems and the detector, all “slow control” signals are included inside power cabling to the power supplies. Therefore, control signals share the same reference potential and shielding as the detector power. 12-Jan-2003 6 Grounding, Power Distribution and New Readout Technologies

ID Power Distribution Issues Power distribution for the ID has two main issues: Voltage drop from power supplies to electronics The SCT, for example, currently draws ~1.2A/circuit. The cable run is ~130m resulting in a voltage drop of about 6V for the 3.5V and 4.0V circuits. Space for cables, especially through the gap region All the available space in the gap region is now allocated for existing services. We are using unusual (i.e. thin insulation) cables in order to fit now. We will have to be creative to service more channels. 12-Jan-2003 7 Grounding, Power Distribution and New Readout Technologies

Grounding, Power Distribution and New Readout Technologies The Voltage Drop Issue The voltage drop not only wastes power as heat in the cable. Sudden reduction of current draw (e.g. loss of clock reduces current in digital logic by ~40%) results in large increase in voltage at the detector, possibly exceeding maximum voltage rating of electronics. SCT now has voltage limiter circuits at PP3 to prevent over voltage in such cases. This will only become worse with next generation technologies, which operate at lower voltages. The lower operating voltages of the new technologies can help to lower the power dissipation but that is not enough. The current requirement also must be maintained or hopefully decreased. Another option to be investigated is a voltage limiter built into the readout electronics or possibly even on-board voltage regulators. 12-Jan-2003 8 Grounding, Power Distribution and New Readout Technologies

Grounding, Power Distribution and New Readout Technologies Cable Volume Issue The current ID being prepared for installation will fill all the available space available in the gap areas. If the ID upgrade will increase channel count, we will have to be creative in how we utilize existing cables or existing space. If current requirements per channel can be reduced, it would be possible to redefine granularity of detector modules/cable. 12-Jan-2003 9 Grounding, Power Distribution and New Readout Technologies

SCT Cable Passing thru Gap Pos 1 Quad of insulated wires 2 wires of AWG 20 (power) 2 wires of AWG 28 (sense) Pos 2 Pos 3 Twisted pair of AWG 28 (500V sensor bias) Pos 4 Twisted 3 wires of AWG 28 (control) Pos 5 Pos 6 Drain wire non insulated - 1 wire of AWG 24 Pos 7 Shield of aluminium polyester tape in contact with the drain wire Pos 8 Outer jacket FRNC Outer Diameter 5.5mm Cu for power = 64% total Cu 12-Jan-2003 10 Grounding, Power Distribution and New Readout Technologies

Development Work is Needed Some options for power distribution in an all silicon ID: Replace all TRT services with new services for outer silicon. Should include some gas lines as well. Certainly not sufficient by itself. Reduce current per channel by 2x to 4x to solve voltage drop problem as operating voltages decrease. Reduce current per channel by 2x to 4x and re-optimize granularity of channels/cable to service more channels. This will maintain similar voltage drop issue so limiters or regulators must also be developed. Find added paths for cables to exit ID 12-Jan-2003 11 Grounding, Power Distribution and New Readout Technologies

UMC CMOS/BiCMOS technology “roadmap” from Paul O’Connor 12-Jan-2003 12 Grounding, Power Distribution and New Readout Technologies

Technology options from Paul O’Connor 2. Silicon Germanium BiCMOS: Adding a graded SixGe1-x layer grown by Molecular Beam Epitaxy creates a high-performance npn bipolar transistor which can be integrated with standard bulk CMOS. The bipolar transistor has excellent high frequency properties (e.g. 200 GHz fT), also low current and voltage gain,1/f noise, good radiation resistance, and works at cryogenic temperatures. This technology is being driven by RF communication and disk-drive markets. SiGe is a relatively new technology, volume production for the last 4 years. Many of the major foundries (IBM, TSMC) and some smaller ones (AMS) are starting to offer SiGe. Wafer size smaller than bulk CMOS, costs higher. More information: J. Cressler’s talk at FEE2003: http://www-ppd.fnal.gov/EEDOffice-w/conferences/FEE_2003/FEE2003talks/A3_Cressler.pdf 12-Jan-2003 13 Grounding, Power Distribution and New Readout Technologies

Technology Comparison From the SCIPP Proposal for Advanced Research Development Estimates by Ned Spencer 12-Jan-2003 14 Grounding, Power Distribution and New Readout Technologies