slide1
Download
Skip this Video
Download Presentation
Multichannel Analyzer (MCA)

Loading in 2 Seconds...

play fullscreen
1 / 31

Multichannel Analyzer (MCA) - PowerPoint PPT Presentation


  • 105 Views
  • Uploaded on

Multichannel Analyzer (MCA). Raphael Cherney Dan Elg Sam Sun Chen Wang. Background: X-ray Detection. X-ray photons. V signal. X-ray Detector. Amplifier. NASA’s detectors can “see” individual X-ray photons Photon  V pulse Height proportional to energy

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Multichannel Analyzer (MCA)' - sonja


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
slide1
Multichannel Analyzer (MCA)
  • Raphael Cherney
  • Dan Elg
  • Sam Sun
  • Chen Wang
slide2
Background: X-ray Detection

X-ray photons

Vsignal

X-ray Detector

Amplifier

  • NASA’s detectors can “see” individual X-ray photons
  • Photon  Vpulse
    • Height proportional to energy
  • Our MCA measures the pulse heights and their times of arrival

MCA

slide4
Applications
  • Radiation detection
  • Nuclear power
  • Food industry
  • *X-ray spectroscopy
  • Non-destructive testing
  • Environmental analysis and monitoring
slide5
Our Task
  • Build a $25 multichannel analyzer
  • Handle pulses ranging from 100 ns to 100 us (Require 1-50 us)
  • 100,000 counts per second (Require 1000 pulses)
  • Handle pulse height from 0V to 10V
  • Output ASCII file with time and pulse height
  • Create histogram of pulse heights

V

vpulse

tpulse

t

slide7
Building an MCA

Baby steps…

Circuits can be fun!

slide8
Signal In

(10 V Analog)

slide9
Signal In

(10 V Analog)

Variable Gain Amplifier

slide10
Signal In

(10 V Analog)

Variable Gain Amplifier

slide11
Fast Signal Bypass

Signal In

(10 V Analog)

Variable Gain Amplifier

slide12
Fast Signal Bypass

Threshold

Signal In

(10 V Analog)

Variable Gain Amplifier

Adjustable

Threshold

Fast Comparator

slide13
Fast Signal Bypass

Threshold

Signal In

(10 V Analog)

Variable Gain Amplifier

Adjustable

Threshold

Fast Comparator

slide14
Fast Signal Bypass

Signal In

(10 V Analog)

Adjustable

Threshold

Variable Gain Amplifier

Fast Comparator

Peak and Hold

slide15
Fast Signal Bypass

Signal In

(10 V Analog)

Adjustable

Threshold

Variable Gain Amplifier

Fast Comparator

Analog to Digital Converter

Peak and Hold

slide16
Fast Signal Bypass

PIC

Signal In

(10 V Analog)

Pulse Counter

Adjustable

Threshold

Peak Value

Variable Gain Amplifier

Fast Comparator

Analog to Digital Converter

Peak and Hold

slide17
PIC Clock Cycles
  • Missed pulse??
slide18
PIC Clock Cycles
  • Missed pulse??
  • Actually, no.
    • Hardware counter
    • Limit processing time by using analog circuitry
slide19
Signal In

(10 V Analog)

PIC Processor

D-type Flip-Flop

Adjustable

Threshold

Signal Latch

Pulse Counter

Peak Value

Fast Comparator

Analog to Digital Converter

Peak and Hold

slide20
Coincidence / Anticoincidence

Primary Signal

Secondary Signal

  • Always need to reset peak and hold

Coincidence

Anticoincidence

slide22
Threshold

Baseline

Reset

Reset

Zoom-in

After detecting rising-edge of comparator, count x (in this case 5) clock pulses, then enable ADC

Assuming 800 kcps, the ADC takes 1.25 μs to sample

Timing Diagram

1 horizontal unit = 5 clock cycles = 250 ns

slide23
Onboard Histogram
  • Stores data on PIC
  • Detection system  ADC  Histogram
  • Allows us to count quickly without having to send data quickly
slide24
USB
  • Wait  send data  wait
  • Sends ~1 kB every time
  • Full-speed bulk transfer

Packet Formation

Buffer Descriptors

USB SIE

Histograms

Endpoint Buffers

Ready?

slide25
Host

Application

Histogram

Incoming data

Flux Plot

File I/O

slide27
UV Flux Monitor
  • Photodiode outputs current according to flux
  • Converted into voltage, read by PIC
  • Uses onboard PIC ADC

UV Light

Isignal

Vsignal

Current-to-

Voltage

Converter

UV Photodiode

PIC

slide28
Final Deliverables
  • An MCA
  • A UV Flux Monitor
  • Software to control these two devices, and display data
slide29
What Now?
  • Test firmware
  • Finish GUI
  • Rev 2 of PCB
  • System integration and final testing
  • Write documentation
slide30
Special thanks to:
  • Steve Holt
  • Keith Gendreau
  • Brad Minch
  • Gill Pratt
  • Mihir Ravel
  • 2008 MCA team

Questions?

ad