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Registered Member #2431
Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
Proud Mary wrote ...
If it was my problem, I would choose a PIN diode gamma ray spectrometer. The PIN diode array, its charge amplifiers, and telemetry modulator drivers would weigh very little. The Multichannel Analyzer (MCA) at the ground station would, with suitable software, directly identify the radionuclides responsible.
i need your guys' opinions for this very reason. this does sound more useful.
Registered Member #543
Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
Patrick wrote ...
Proud Mary wrote ...
If it was my problem, I would choose a PIN diode gamma ray spectrometer. The PIN diode array, its charge amplifiers, and telemetry modulator drivers would weigh very little. The Multichannel Analyzer (MCA) at the ground station would, with suitable software, directly identify the radionuclides responsible.
i need your guys' opinions for this very reason. this does sound more useful.
Why not, at this stage, simply consider using an onboard data logger having a number of digital and analogue inputs? The data logger output would be coded (PCM multiplexing?) and delivered to the RF modulator, and thence sent to the ground. station.
An infrared thermometer deriving temperature from black body radiation could be one of your sensors, both to report the condition of hot surfaces, and to safeguard the flying machine itself from excess radiated heat.
This approach would allow you to fit a range of different sensor modules according to the needs of the job in hand.
Registered Member #2431
Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
Proud Mary wrote ...
Patrick wrote ...
Proud Mary wrote ...
If it was my problem, I would choose a PIN diode gamma ray spectrometer. The PIN diode array, its charge amplifiers, and telemetry modulator drivers would weigh very little. The Multichannel Analyzer (MCA) at the ground station would, with suitable software, directly identify the radionuclides responsible.
i need your guys' opinions for this very reason. this does sound more useful.
Why not, at this stage, simply consider using an onboard data logger having a number of digital and analogue inputs? The data logger output would be coded (PCM multiplexing?) and delivered to the RF modulator, and thence sent to the ground. station.
An infrared thermometer deriving temperature from black body radiation could be one of your sensors, both to report the condition of hot surfaces, and to safeguard the flying machine itself from excess radiated heat.
This approach would allow you to fit a range of different sensor modules according to the needs of the job in hand.
modularity is one of the methodologies i really prefer.
Registered Member #543
Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
You might do best to focus your attention on producing a stable flying platform and its associated command and control circuits.
Once you have that, I can see nothing inherently difficult about taking the outputs of sensors and HD video and sending them down to your control station. You might even be able to use cell phone technology to provide some of your data channels.
I would keep the command and control channel/s completely separate from the data telemetry channel/s, so errors can not so easily spread.
Registered Member #230
Joined: Tue Feb 21 2006, 08:01PM
Location: Gracefield lower Hutt
Posts: 284
The best bet is to silver plate /evaporate silver around the outside of a gieger tube with a layer of wax approx 2.5cm thick around it to thermalise the neutrons, the silver is activated by the thermalised neutrons and releases Betas for the tube to count. Good side is that the tube also responds to gammas. if the gamma function is not needed then thin lead around the outside will attenuate the lesser energy gammas to approx 100keV
If it was my problem, I would choose a PIN diode gamma ray spectrometer. The PIN diode array, its charge amplifiers, and telemetry modulator drivers would weigh very little. The Multichannel Analyzer (MCA) at the ground station would, with suitable software, directly identify the radionuclides responsible.
If the goal is to find out, whether there is still fission going on in a damaged reactor, the identification of gamma rays coming from short lived (e.g. 1h) fission fragments would be a strong indicator. Pin diodes can measure only the energies of low energy gammas. They will deposit all of their energy by the photo effect in the sensor. Higher energy gammas will just be scattered and can be detected, but their energy cannot be determined. You'd need a rather clear view of the damaged core to measure low energy gammas, since they are easily blocked by debris.
Registered Member #543
Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
Uspring wrote ...
Proud Mary wrote:
If it was my problem, I would choose a PIN diode gamma ray spectrometer. The PIN diode array, its charge amplifiers, and telemetry modulator drivers would weigh very little. The Multichannel Analyzer (MCA) at the ground station would, with suitable software, directly identify the radionuclides responsible.
If the goal is to find out, whether there is still fission going on in a damaged reactor, the identification of gamma rays coming from short lived (e.g. 1h) fission fragments would be a strong indicator. Pin diodes can measure only the energies of low energy gammas. They will deposit all of their energy by the photo effect in the sensor. Higher energy gammas will just be scattered and can be detected, but their energy cannot be determined. You'd need a rather clear view of the damaged core to measure low energy gammas, since they are easily blocked by debris.
You are right to say that a PIN photodiode would only be suitable for direct detection at long wavelengths. We would need a suitable crystal or plastic scintillator in front of the PIN diodes for effective gamma spectrometry, and I am sorry I did not make myself more clear.
Registered Member #96
Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4061
IR thermometer + directional Geiger tube (ie edge filtered) would be a winner methinks. IR thermometry has been used from space to gauge cloud temperatures and in fact the early nuclear test detection/early warning systems were based on this.
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Neutron scintillation detector.
