Some tests of LARASIC 7 and 8 The Ledge Effect and more November - PowerPoint PPT Presentation

Some tests of LARASIC 7 and 8 The Ledge Effect and more November 19, 2018 MSU Group Dean Shooltz Carl Bromberg Kendall Mann Dan Douglas Elizabeth Nicometo November 19, 2018 MSU Physics and Astronomy 1

Outline Background Experimental setup Initial results Next steps November 19, 2018 MSU Physics and Astronomy 2

Characteristic shape of the “Ledge Effect” Slide copied from 10/15/2018 presentation by Hucheng Chen, Shanshan Gao, Veljko Radeka – First noticed by Tom Junk by inspection of ProtoDUNE run data – Appears when large amount of charge is delivered to LARASIC – Initial tests at BNL show that the Ledge Effect largely disappears with 900 mV baseline setting – Duration of current input also plays a role – ProtoDUNE now running with 900 mV baseline on all channels November 19, 2018 MSU Physics and Astronomy 3

Test Stand at Michigan State University Quad Socket FEASIC tester from BNL – Stretched version arrived Oct. 9 th -Thanks! –I’ve Modified firmware, C# backend, LabView – Real time control and data display (20,000 points, 5 msec) – FPGA delivers trigger to external signal generator – System handles like an oscilloscope – Can set ASIC parameters and readout traces in ~50 msec – Can set up LabView to process ~ 1000 traces/minute – Using a signal generator to send voltage ramps into FEASIC test capacitance (185 fF) 185 fF Image stolen from BNL talk 10/15/2018 November 19, 2018 MSU Physics and Astronomy 4

Look in detail at the threshold voltage required to give the Ledge Effect waveform – enabled by using a real-time system Also compare results across three generations of LARASIC November 19, 2018 MSU Physics and Astronomy 5

Perform the following tests Try 200 mV and 900 mV baseline settings – No Ledge Effect seen with 900 mV baseline setting (up to 1500 mV to test cap) – Agrees with BNL observation Try all four different gain settings – Does not change Ledge Effect Try all four different peaking time settings – Does not change Ledge Effect Try adjust neighbor channels – Does not seem to change Ledge Effect Try turning the Output Buffer ON/OFF – Does not seem to change the Ledge Effect Try adjusting the Leakage Current – This has a significant effect November 19, 2018 MSU Physics and Astronomy 6

Look in detail at the threshold voltage required to give the Ledge Effect waveform – enabled by using a real-time system Adjust the FEASIC Leakage Current setting November 19, 2018 MSU Physics and Astronomy 7

Hall of Fame: longest Ledge Effect seen in 176 tested FEASIC channels V7 chip P2-11 channel 14 Duration about 1.4 millisec November 19, 2018 MSU Physics and Astronomy 8

Ramp time can have a big influence on signal shape at 900 mV baseline Ramp voltage 1500 mV Effect is a function of ramp time and voltage: – Threshold is 320 mV at 1 usec, 1090 mV at 10 usec, 1170 mV at 20 usec 50 usec 35 usec 30 usec 25 usec 20 usec 10 usec November 19, 2018 MSU Physics and Astronomy 9

Hypersensitivity to duration of current pulse below regime of the Ledge Effect 700 mV amplitude ramp 1.5 usec 1.6 usec 1.7 usec November 19, 2018 MSU Physics and Astronomy 10