Argonne National Laboratory is a U.S. Department of Energy laboratory managed by U Chicago Argonne, LLC. • 2 nd Measurement – Feb., 2011 – Test board with individual components – 188 MeV protons – Discovered: LT1681 Controller Chip trips & restarts – Diode conducts at cold start – Diode is back biased – SEUs still happen, but recovery is fast The TileCAL Low Voltage System Radiation Testing Methodology Measurements & Results • Power for TileCAL Front-End Electronics • Novel Switching DC-DC Power Supply – Custom, Compact, High-Efficiency, 250 Watt – 8 Different Voltages Customized Bricks – Water Cooled; System Interface & Monitoring – Environment: Magnetic Field, Radiation Tolerant • 256 boxes on detector, 2048 bricks, + spares Reliability is Important Infrequent Access End of Long Barrel Detector Section LVPS Access on Detector Drawer Electronics LVPS Box 8 bricks per Box LVPS Brick Single Event Upset Energy Dependence In a Buck-Converter Power Supply Design Bruce Mellado 2 , Anusha Gopalakrishnan 1 , Sanish Mahadik 1 , Robert Reed 2 , Abhirami Senthilkumaran 1 1 - University of Wisconsin-Madison, Madison, WI USA 2 – The University of the Witwatersrand, Johannesburg, SA On Behalf of the ATLAS Tile Calorimeter System Gary Drake , Member IEEE, James Proudfoot Argonne National Laboratory, Lemont, IL USA • The Fix – Soft Start not used in brick operation – But, circuit does control startup rate Want capacitor for cold start Want capacitor out of circuit for normal operation Add a diode & resistor: • Radiation Tolerance Requirements – 10 Years of Running, L = 10 34 cm -2 sec -1 • 1 st Measurement – Dec., 2010 – Bricks tripped from SEU – 188 MeV protons SEU Problem We have performed a study of the susceptibility to Single Event Upsets (SEU) on the new upgraded supplies TID (Grays) NIEL Fluency (neutrons/cm 2 ) SEE Fluency (protons/cm 2 ) 3.78 2.74x10 11 6.74x10 10 • SEU Testing Program – Proton beam at Mass. Gen. Hospital – 20 – 200 MeV protons – Read out continuously during irradiation Soft-start capacitor External component Value controls startup delay Schematic LT1681 Block Diagram Soft Start Feature • A Puzzle – SEUs not seen in earlier tests at 60 MeV – Why?... • 3 rd Measurement – Apr., 2011 – Fix installed on 3 bricks – No more trips! • 4 th Measurement – Apr., 2012 Study SEUs as a function of energy – 60 MeV, 80 MeV, 100.5 MeV, 140 MeV, & 216 MeV – Results: See energy dependence Test Setup at MGH Test Setup Configuration Block Diagram of Brick • Theory: Bendel Parameters [1] – In general, SEU susceptibility depends on fab tech., feature size, layout, and configuration – Bendel Parameters: Parameterization of form: –Our fit: [1] W.J.Stapor, et al., IEEE Trans Nucl. Sci., Vol. 37, NO.6, pp. 1966-1973, December 1990. To ELMB (Contro l Interfa ce) Startu p Shutdow n Opto Isolator Opto Isolator Monitor Voltages V IN* I IN* LT1681 Controller Chip + Vout - FET Driver R SHUNT V FB I FB Transformer GND SEC GND PRI Startup & Shutdow n Control OVP, OCP, Temp, & Monitor R SHUNT LC Filter + 200V - LC Buck LC Filter OpAmp Run Stop Over Temp V OUT* I OUT * PRI Power SEC Power + V SEC - + V PRI - Isolated Secondary Primary SEMI-EMPIRICAL 2 PARAMETER FIT