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Project Resources:
https://docs.google.com/document/d/1uMhZbrjy4h7P3S4hgvYHxCAvWjgHozcVUgSRDQH5D5s/edit?usp=sharing
launch canada design proposal https://docs.google.com/document/d/1O7Zn6XXuKUzf7-EnrcJN0tukMsXGqb2XmS91orYVu7I/edit?usp=sharing irec final report (starting p 40)
https://docs.google.com/document/d/1rbeQXoqX3_iZjQlVWfSDjXrRMNYCyoMgeSvU2urp8gc/edit
https://docs.google.com/document/d/1KT3We5JVC4YxGNyok1LQRfJvyCAvVPx5eveaM_oDLg-100HUN1bcSWUTdOZXlH0dCf8oV8NaFBstOVcZV9izbM/edit?usp=sharing
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Overview***********************************
Measuring the radiation detection properties of BNNTs and Metal Oxides.
Radiaiton detection
Scintillator - Lights up when exposed to ionizing radiation
SiPM - Silicon photomultiplier, sensor that counts the number of photons it sees.
Scintillator generates light, SiPM generates a current pulse proportional
to the magnitude of radiation.
In order to detect and log that current pulse on an MCU we need to
1. Convert the current signal to voltage
2. Amplify the voltage pulse to increase difference between singal and noise
and make it easier to detect and losses negligible.
3. Extend the length of the signal so the MCU has time to made an ADC conversion.
Detector Circuit Topology:
1. Transimpdance amplifier converts current signal to voltage, amplifies it in a way
to reduce the signal to noise ratio. The main purpose of this board is to fine-tune the
resistor and capacitor values to optimize the gain on this amplifier.
2. Filter stage to eliminaty high and low frequency noise
3. Second stage amplfication
4. Peak detector to extend signal
5. Voltage follower to ensure signal sampling does not interfere with the peak detector circuit.
Data logging:
After the second stage amplificaiton, the signal line is sent to both the peak detector and a comparator.
The comparator compares the signal to a set baseline voltage value, and if the signal exceeds this amount,
it generates an interrupt. This interrupt is used to tell the MCU when to take an ADC sample from the
peak detector line. |
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Data logging:
After the second stage amplificaiton, the signal line is sent to both the peak detector and a comparator.
The comparator compares the signal to a set baseline voltage value, and if the signal exceeds this amount,
it generates an interrupt. This interrupt is used to tell the MCU when to take an ADC sample from the
peak detector line.
Voltage supply:
Because the detector circuit is sensative anlaog circuitry, it runs off a seperate 4.7V line
from an LDO. The LDO cleans the 5V line to ensure low-noise, as well as seperates the detector
circuit supplies from any noise generated by the switching supplies.
The SiPM requires 36V to operate. This is achieved with a voltage booster paried with an LDO to
make sure the supply voltage is clean.
The detector_support circuit is configured to support both a test connection (5V and 12V from the
bench top supply) as well as battery connections for use in lab testing. |
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Functionality:
Radiation detection:
Scintillator generates light, SiPM generates a current pulse proportional
to the magnitude of radiation.
Scintillator - Piece of plastic that lights up when exposed to ionizing radiation
SiPM - Silicon photomultiplier, light sensor that “counts” the number of photons it sees, by producing a small current proportional to #photons detected
In order to detect and log that current pulse on an MCU (microcontroller unit) we need a detector circuit to:
Convert the current signal to voltage
Amplify the voltage pulse to increase difference between signal and noise
and make it easier to detect and losses negligible. This is done by the detector circuit.Extend the length of the signal so the MCU has time to made an ADC conversion.
Detector Circuit Topology:
Transimpdance amplifier converts current signal from SiPM to voltage, amplifies it in a way
to reduce the signal to noise ratio.Filter stage to eliminate high and low frequency noise
Second stage amplification
Peak detector to extend signal
Voltage follower to ensure signal sampling does not interfere with the peak detector circuit.
Data logging:
After the second stage amplification, the signal line is sent to both the peak detector and a comparator.
The comparator compares the signal to a set baseline voltage value, and if the signal exceeds this amount,
it generates an interrupt. This interrupt is used to tell the MCU when to take an ADC (analog to digital conversion) sample from the
peak detector line.
Voltage supply & Power Management:
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Because the detector circuit is sensitive analog circuitry, it runs off a separate 4.7V line
from an LDO. The LDO cleans the 5V line to ensure low-noise, as well as separates the detector
circuit supplies from any noise generated by the switching supplies.
The SiPM requires 36V to operate. This is achieved with a voltage booster paired with an LDO to
make sure the supply voltage is clean.
The detector_support circuit is configured to support both a test connection (5V and 12V from the
bench top supply) as well as battery connections for use in lab testing.
PWR_EN - Signal that allows us to turn on/off the radiation detectors to reduce power usage while sitting on the pad
VERY BASIC OVERVIEW of commonly used voltage supplies:
LDO - Linear regulator, clean but highly inefficient voltage regulator. Can only produce voltages below input. Very simple to implement.
Switching regulator - efficient regulator, noisy, more difficult to implement
Buck regulator - switching regulator that generates output voltage below input voltage
Boost regulator - switching regulator that generates output voltage above input voltage
System Layout
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