CHARACTERIZATION AND OPTIMIZATION OF PREAMPS FOR THE MU2E TRACKER P - - PowerPoint PPT Presentation

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CHARACTERIZATION AND OPTIMIZATION OF PREAMPS FOR THE MU2E TRACKER P - - PowerPoint PPT Presentation

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CHARACTERIZATION AND OPTIMIZATION OF PREAMPS FOR THE MU2E TRACKER P E R I A N N E J O H N S O N S I S T I N T E R N , F N A L P P D N E W M E X I C O I N S T I T U T E O F M I N I N G A N D T E C H N O L O G Y 1 4 August 2014

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SLIDE 1

CHARACTERIZATION AND OPTIMIZATION OF PREAMPS FOR THE MU2E TRACKER

P E R I A N N E J O H N S O N S I S T I N T E R N , F N A L P P D N E W M E X I C O I N S T I T U T E O F M I N I N G A N D T E C H N O L O G Y

4 August 2014

PERIANNE JOHNSON

1

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SLIDE 2

OVERVIEW

  • General Background on Mu2e
  • Preamp Specifications
  • Original Preamp
  • Modifications
  • New Design
  • Future Improvements

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SLIDE 3

MU2E: CHARGED LEPTON FLAVOR VIOLATION

  • Neutrinoless conversion of a muon into an electron
  • Rare event – rates predicted by SM theory of < 10-50
  • Effectively, one event could imply New Physics

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SLIDE 4

MU2E: STRAW TRACKER

  • 5 mm mylar straw with wire running through it, potential difference draws

ionized ArCO2 to wire, creating current

  • Array tracks path of particles
  • Preamp at each end – distance determination

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SLIDE 5

PREAMPS: BASICS

  • Small printed circuit board (4.0 by 1.1 cm by 31 mils)
  • Amplifies an input signal at an inherent gain

​𝐻 ​𝐻𝑏𝑗𝑜↓𝑒𝐶 =20 =20​lo log↓10 10 ⁠(​𝐵 (​𝐵↓𝑝𝑣𝑢 /​𝐵 ​𝐵↓𝑗𝑜 ) )

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SLIDE 6

PREAMPS: SCHEMATIC

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Bala lanc nce Point nt

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SLIDE 7

PREAMPS: MOTHERBOARD

  • Provides power, programming via 1-Wire, and viewing of output signal for eight preamps
  • Mounted very close together – cross talk

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Cha hanne nnels ls 1-Wire C Chi hips Arduino no Conne nnector Sc Scope pe Cable les

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SLIDE 8

PREAMPS: PROGRAMMING

  • One Wire Chip – 8 Channel Addressable Switch
  • Arduino Due Microcontroller
  • Python

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SLIDE 9

PREAMPS: “READ.PY”

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Time (ns)

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SLIDE 10

ORIGINAL PREAMPS

  • No shaping
  • Soldered directly to motherboard
  • 2.5 mV input peak-to-peak amplitude from signal generator

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SLIDE 11

ORIGINAL PREAMPS: CROSS TALK

  • Unavoidable fact of close mounting
  • Mounted second preamp into channel 6 on motherboard
  • Two percent limit for final experiment

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SLIDE 12

NEW PREAMPS: SHAPING

  • Addition of 100 pF capacitor to shape (“boost”) gain at 100 MHz
  • Factor of five increase
  • Input Signal: 50 mV attenuated by 38 dB – 0.63 mV

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SLIDE 13

INSTABILITY: REMOVAL OF CAPACITOR

  • Boosting made the preamps very sensitive to movement / touching
  • Touching preamps adds capacitance where it doesn’t belong
  • Shaping capacitor was removed from eight preamps

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Preamp # ¡ Balance # ¡ Voltage Drop ¡ Output Amplitude (mV) ¡ Noise RMS ¡ 0 ¡ 22800 ¡ 70 ¡ 21 ¡ 0.35 ¡ 1 ¡ 22600 ¡ 74 ¡ 23 ¡ 0.38 ¡ 2 ¡ 22900 ¡ 65 ¡ 48 ¡ 0.6 ¡ 3 ¡ 22400 ¡ 74 ¡ 21 ¡ 0.34 ¡ 4 ¡ 22300 ¡ 75 ¡ 21 ¡ 0.36 ¡ 5 ¡ 23100 ¡ 70 ¡ 24 ¡ 0.36 ¡ 6 ¡ 21800 ¡ 73 ¡ 20 ¡ 0.33 ¡ 7 ¡ 22300 ¡ 71 ¡ 22 ¡ 0.35 ¡

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SLIDE 14

INSTABILITY: BFP520 VERSUS BFP720

  • Originally, two 720s for input and three 520s for output
  • BFP720: Si-Ge material allows for faster transition frequency and greater

bandwidth

  • Via not well grounded – small piece of copper tape

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SLIDE 15

BFP 520 + COPPER TAPE

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SLIDE 16

BETTER GROUNDING FOUND

  • Large ground plane right by components that rely on via
  • Flipped them around and soldered, now well grounded

PERIANNE JOHNSON

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SLIDE 17

FINAL PREAMPS: GAIN

  • All BFP520 transistors, shaping capacitor replaced, components flipped to ground

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SLIDE 18

FINAL PREAMPS: CROSS TALK

  • Above the requisite two percent, no further testing done at this point

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SLIDE 19

CONCLUSIONS & FUTURE MODIFICATIONS

  • 52 db gain for preamps with:
  • BFP520 transistors throughout
  • Shaping capacitor
  • Better grounding
  • Original preamps: gain of 30 dB
  • Future Modifications:
  • Better grounding for components built into layout
  • Reduction of cross talk to signal ratio

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SLIDE 20

QUESTIONS?

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SLIDE 21

REFERENCES

DS2408: 1-Wire 8-Channel Addressable Switch http://www.maximintegrated.com/en/products/digital/memory-products/ DS2408.html Arduino Due Microcontroller http://arduino.cc/en/Main/ArduinoBoardDue

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SLIDE 22

ACKNOWLEDGEMENTS

Several parties are deserving of recognition for the success of this project and summer internship. I would first like to thank my supervisor, Dr. Vadim Rusu, for providing me with ample guidance and support throughout my project, while also allowing me to learn from my own mistakes. I would also like to thank my assistant supervisor, Aseet Mukherjee, and coworker Angela Yang for always lending her third hand. Finally, I would like to recognize Elliot McCrory, Dianne Engram, Linda Diepholz and the rest of the SIST Committee for selecting me to be a part of this program.

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