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#1 Mike Brennan

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Posted 26 November 2007 - 05:42 PM

Jim,
further to this thread

http://www.cinematog...n...st&p=183752


about Gamma radiation affecting ccds, how is RED shaping up in this regard?

Also have you noticed cosmic radiation hits that lightup one pixel for one frame in duration, can be seen live with a large monitor and eyes well adjusted to dark.
Happens in SD and HD ccd cameras wondering how it effects larger CMOS sensors.

The hit is coloured in three chip cameras depending on which ccd that gets hit.
Can be mistaken for recording problem or dust on filmouts ect.

Some more reading here http://www.stsci.edu...HTML/W2_41.html

I've seen them at a rate of 4 per minute in UK.


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#2 David Mullen ASC

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Posted 26 November 2007 - 06:59 PM

Also, is there a "dead pixel" correction thru black balancing the way there is on a pro video camera?
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#3 Jim Jannard

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Posted 26 November 2007 - 09:04 PM

Also, is there a "dead pixel" correction thru black balancing the way there is on a pro video camera?


I haven't seen anything "cosmic" for many years... :-)

Yes, we do have dead pixel correction. We understand that some companies accept dead rows (and dead row correction). We do not.

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#4 Lance Flores

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Posted 26 November 2007 - 09:21 PM

Jim,
further to this thread

http://www.cinematog...n...st&p=183752

about Gamma radiation affecting ccds, how is RED shaping up in this regard?
<snip>
I've seen them at a rate of 4 per minute in UK.

Mike Brennan


It would indeed be quite a phenomenon to see that rate in that part of the universe. In all the time we studied the alpha particle problem in my lab at Mostek I never observed such a rate. We began observing alpha-particle induced soft error mechanism in NMos devices as we were scaling dynamic memory using 5 microns processes and below. The alpha particle would create electron hole pairs as it passed through the memory cell thus altering the charge sufficiently enough that the sense amp would inaccurately determine the state. OFF being the state susceptible. I designed special test devices (both NMOS and CMOS) to evaluate the ceramic materials we used for industrial and mil spec devices and never saw rates like 4 hits per minute. We had customers like Borroughs, CDC, DEC, LTV Vought and IBM that occasionally made such reports, be each time we evaluated such claims, the data errors were caused by cross coupling of data to data or data to control signals though reactive coupling created by signal patterns. On occasions some solders used in manufacturing had metal whose decay had elevated alpha particle emission.

The rate you are reporting falls well into that of noise not particle induced soft errors in the storage cell. After the read and equilibration the next write (photo detection) cycle the cell would be recovered, after all it's a soft error. The probability of that same cell being hit again, even if the radiation was being emitted from the decaying materials of ceramic packaging is quite small.

I suspect between the deBayering, codec manipulation of the data and frame rate, such soft errors are imperceptible. It is much like what happens in film which integrates defects or rather variances in the oxide crystals, from frame to frame.

There much more important issues to be concerned about than single bit soft errors in the digital acquisition realm of cinematography.
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#5 Mike Brennan

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Posted 27 November 2007 - 01:36 PM

It would indeed be quite a phenomenon to see that rate in that part of the universe. In all the time we studied the alpha particle problem in my lab at Mostek I never observed such a rate. We began observing alpha-particle induced soft error mechanism in NMos devices as we were scaling dynamic memory using 5 microns processes and below. The alpha particle would create electron hole pairs as it passed through the memory cell thus altering the charge sufficiently enough that the sense amp would inaccurately determine the state. OFF being the state susceptible. I designed special test devices (both NMOS and CMOS) to evaluate the ceramic materials we used for industrial and mil spec devices and never saw rates like 4 hits per minute. We had customers like Borroughs, CDC, DEC, LTV Vought and IBM that occasionally made such reports, be each time we evaluated such claims, the data errors were caused by cross coupling of data to data or data to control signals though reactive coupling created by signal patterns. On occasions some solders used in manufacturing had metal whose decay had elevated alpha particle emission.

The rate you are reporting falls well into that of noise not particle induced soft errors in the storage cell. After the read and equilibration the next write (photo detection) cycle the cell would be recovered, after all it's a soft error. The probability of that same cell being hit again, even if the radiation was being emitted from the decaying materials of ceramic packaging is quite small.

I suspect between the deBayering, codec manipulation of the data and frame rate, such soft errors are imperceptible. It is much like what happens in film which integrates defects or rather variances in the oxide crystals, from frame to frame.

There much more important issues to be concerned about than single bit soft errors in the digital acquisition realm of cinematography.


Very interesting but your explanation contradicts what I believe to be Sonys explanation.
Im not taking sides:) here is a little more detail on my experience just to be clear.

Random hits.
There are three ccds of high density so three times the likely hood of cosmic hits?
It happens on cameras from different manufacturers.


The effect was obvious enough (when you really look for it!) of an issue for Sony UK to change the CCD block in my f900 a few years back.
This was a big expensive deal. But then, the same day with new CCD block the hits were still there! Im told Sony Japan then said that it was cosmic radiation, something new to me and the UK engineers! We knew about gamma but cosmic was out of this world.
Then we checked a SD camera under same viewing conditions and bingo we could see it there too. We recorded and played back to identify, so it isn't a monitor issue it goes to tape.

Needs a few dbs of gain a big monitor, dark room black cloth and don't blink and you can see "them".

Just checked the Panasonic 3000 HD camera that I have on test and the rate is two a minute at 1730GMT.


Will be very interested to know of manufacturing or inherent design issues that could cause these sparkles if the cosmic theory is in doubt.

I think it is important to learn about random white hits, in two cases that I've heard about in the UK the lab was blamed for them! When I first saw them during a shoot I considered informing the producer that the camera had developed a minor fault!


More reading here.
http://www.jai.com/S...-CosmicRays.pdf

In REDs case Bayer may well disguise the hit or could make it twice as big?

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#6 Lance Flores

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Posted 28 November 2007 - 08:10 PM

A bunch of guys starring at a big monitor in the dark is not the way you measure soft errors in semiconductor devices. What you are seeing is noise. First you have monitor noise, line noise, power supply noise, cable inductive noise, thermal induced noise along various leakage mechanisms which change bias or back bias and other levels affecting data lines. And that's just the monitor and interface circuits. This doesn't even take in to account all the noise accumulated from the sensor to the input of the monitor cable. Okay, so you caught it on tape. Yeah. Do you here what your saying? A tape, a tape? Now there's a way of insuring there is no noise introduced into your video. Let's see, a magnetic induction device, mechanical friction of mylar over glass/metal sensors, and mylar has an elasticity, humm . . . coefficient of what? And how many mechanical connection circuits, and how many sources in the path are susceptible to noise? Your joking right?

How can you discern all the noise from all these sources, from a single bit soft hit which lasts only 1/24 or 1/30 second, or what ever the refresh rate of the acquisition was?

Such would be akin to putting your head to the ground in Poughkeepsie listening for the biorhythms of a California Condor on Palomar Mountain.

The only credible way to test is in the lab, and testing the device directly under very controlled environments. I could probably think of another dozen or two things to do, but to begin with you need to know what your testing, so you would first probe at wafer before passivation and gather the parametric of the lot. Then you'd put the glass on, scribe, break, package, etc. Then you'd run the packaged devices and test and bin-out. Send them to burn-in and at least get out the infant mortality fallout from contamination, etc. Retest and bin-out again. Then set up the test racks with enough device to give some statical relevance for your observation. I used to run several thousand devices. You would isolate by lots and bin-out parametric. Probably would eliminate the bayer mask to eliminate any anomalies induced by the mask for the test. Then you'd test using different patterns of write charge levels, read, write deplete, read, varying then number of writes at varying writes which will leave varying residual charges in the cells so that you can measure cell sensitivity/susceptibility to particle impingement as well as the soft error. All this has to be done in a very controlled environment for any kind of quantifiable and qualified measurement.

My guess is that, if you put a bucket under your camera to catch all those cosmic particles and come back in an hour or two, you'll find it full of red herrings.

As far as the Red's debayering algorithm making an error "twice as big" . . . huh? Do the math.



<snip>
Then we checked a SD camera under same viewing conditions and bingo we could see it there too. We recorded and played back to identify, so it isn't a monitor issue it goes to tape.

Needs a few dbs of gain a big monitor, dark room black cloth and don't blink and you can see "them".

Just checked the Panasonic 3000 HD camera that I have on test and the rate is two a minute at 1730GMT.

Will be very interested to know of manufacturing or inherent design issues that could cause these sparkles if the cosmic theory is in doubt.

I think it is important to learn about random white hits, in two cases that I've heard about in the UK the lab was blamed for them! When I first saw them during a shoot I considered informing the producer that the camera had developed a minor fault!


More reading here.
http://www.jai.com/S...-CosmicRays.pdf

In REDs case Bayer may well disguise the hit or could make it twice as big?

Mike Brennan


Edited by Lance Flores, 28 November 2007 - 08:14 PM.

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#7 Mike Brennan

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Posted 29 November 2007 - 06:45 PM

A bunch of guys starring at a big monitor in the dark is not the way you measure soft errors in semiconductor devices. What you are seeing is noise. First you have monitor noise, line noise, power supply noise, cable inductive noise, thermal induced noise along various leakage mechanisms which change bias or back bias and other levels affecting data lines. And that's just the monitor and interface circuits. This doesn't even take in to account all the noise accumulated from the sensor to the input of the monitor cable. Okay, so you caught it on tape. Yeah. Do you here what your saying? A tape, a tape? Now there's a way of insuring there is no noise introduced into your video. Let's see, a magnetic induction device, mechanical friction of mylar over glass/metal sensors, and mylar has an elasticity, humm . . . coefficient of what? And how many mechanical connection circuits, and how many sources in the path are susceptible to noise? Your joking right?

How can you discern all the noise from all these sources, from a single bit soft hit which lasts only 1/24 or 1/30 second, or what ever the refresh rate of the acquisition was?

Such would be akin to putting your head to the ground in Poughkeepsie listening for the biorhythms of a California Condor on Palomar Mountain.

The only credible way to test is in the lab, and testing the device directly under very controlled environments. I could probably think of another dozen or two things to do, but to begin with you need to know what your testing, so you would first probe at wafer before passivation and gather the parametric of the lot. Then you'd put the glass on, scribe, break, package, etc. Then you'd run the packaged devices and test and bin-out. Send them to burn-in and at least get out the infant mortality fallout from contamination, etc. Retest and bin-out again. Then set up the test racks with enough device to give some statical relevance for your observation. I used to run several thousand devices. You would isolate by lots and bin-out parametric. Probably would eliminate the bayer mask to eliminate any anomalies induced by the mask for the test. Then you'd test using different patterns of write charge levels, read, write deplete, read, varying then number of writes at varying writes which will leave varying residual charges in the cells so that you can measure cell sensitivity/susceptibility to particle impingement as well as the soft error. All this has to be done in a very controlled environment for any kind of quantifiable and qualified measurement.

My guess is that, if you put a bucket under your camera to catch all those cosmic particles and come back in an hour or two, you'll find it full of red herrings.

As far as the Red's debayering algorithm making an error "twice as big" . . . huh? Do the math.




Well at the time we weren't trying to measure soft errors we were looking out to initially identify that white specs were in the camera.


Yes by catching it on tape it proved that it was something originating in the camera and not a monitor issue.

How can we see them amid the noise? well the hits are much brighter than the camera noise and are clean, they are quite easy to see!

I don't understand all of the detail of what you wrote, but have you seen the effect as presented on a HD camera output?


In respect to buckets of herrings you could be right, but nothing less than an examination of a HD camcorder using your test method is likely to replace the cosmic/gamma radiation story we have been fed from NHK, Sony JVC and NASA.



Here is a link to a report on the NHK HD camera in the International Space station that NHK say suffered 150 cosmic hits that were strong enough to keep the pixel hot. http://idb.exst.jaxa...df/STJ85-14.pdf

Also here is an freely available extract, available from the technical reports server of a NASA study saying HD cameras seem to be more prone to cosmic hits than SD cameras. Full report here;
http://ntrs.nasa.gov.....294967190+269

"Recent experience using high definition video on the International Space Station reveals camera pixel degradation due to particle radiation to be a much more significant problem with high definition cameras than with standard definition video. Although it may at first appear that increased pixel density on the imager is the logical explanation for this, the ISS implementations of high definition suggest a more complex causal and mediating factor mix. The degree of damage seems to vary from one type of camera to another, and this variation prompts a reconsideration of the possible factors in pixel loss, such as imager size, number of pixels, pixel aperture ratio, imager type (CCD or CMOS), method of error correction concealment, and the method of compression used for recording or transmission. The problem of imager pixel loss due to particle radiation is not limited to out-of-atmosphere applications. Since particle radiation increases with altitude, it is not surprising to find anecdotal evidence that video cameras subject to many hours of airline travel show an increased incidence of pixel loss. This is even evident in some standard definition video applications, and pixel loss due to particle radiation only stands to become a more salient issue considering the continued diffusion of high definition video cameras in the marketplace."


So most techies agree that cosmic radiation causes stuck or dead pixels. Do you agree?


To be clear I am referring to white specs where the level of energy isn't enough to make them "dead" and stay white.
Rather it is a transitory hit and discharged by the next frame.
At the time I was lead to believe that Sony link cosmic radiation to both dead pixels and flashing pixels.


A simple way of establishing if the white transient hits are not cosmic rays would be to use the camera deep underground. Would you concur?
Anyone on the list shooting in a salt/coal/gold mine?


In respect of asking the question about a pixel going hot in a bayer pattern sensor I figured that if one green pixel took a hit it would then be used as incorrect scene information to build colour for surrounding pixels, thus making the blemish larger.


Perhaps a Bayer could do the opposite and disguise it if it was a red or blue pixel that was hit, but the NASA report suggests that in-camera processing could also amplify it and they say varies with different sensors and between CMOS and CCDs.




Mike Brennan
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#8 Hal Smith

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Posted 29 November 2007 - 08:25 PM

When HD Network ran their live HD coverage from the Space Station the video picture was full of permanent white dead pixels. Admittedly the cosmic ray and solar wind fluxes are quite a bit stouter in inner space but the hits were energetic enough to hard kill pixels. I actually saw one hit live.
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#9 John Sprung

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Posted 30 November 2007 - 07:02 PM

So most techies agree that cosmic radiation causes stuck or dead pixels. Do you agree?

A simple way of establishing if the white transient hits are not cosmic rays would be to use the camera deep underground. Would you concur?
Anyone on the list shooting in a salt/coal/gold mine?

Cosmic radiation can be one possible cause. But not the only cause.

Going deep under ground would substantially reduce the number of particles of cosmic origin you encounter. But it could introduce loads more radiation from surrounding minerals. Here on the surface, there are places where radon gas comes up from the ground and can reach significant concentrations in buildings. Red clay bricks can contain elements that decay and give off radiation. Perhaps people who live in brick houses shouldn't shoot HD? ;-)

And radiation isn't the only source of tranient hits or noise.





-- J.S.
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#10 Mike Brennan

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Posted 01 December 2007 - 03:45 AM

Cosmic radiation can be one possible cause. But not the only cause.

Going deep under ground would substantially reduce the number of particles of cosmic origin you encounter. But it could introduce loads more radiation from surrounding minerals. Here on the surface, there are places where radon gas comes up from the ground and can reach significant concentrations in buildings. Red clay bricks can contain elements that decay and give off radiation. Perhaps people who live in brick houses shouldn't shoot HD? ;-)

And radiation isn't the only source of tranient hits or noise.





-- J.S.

John,
what are the other possible causes of transient hits?


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#11 Keith Walters

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Posted 01 December 2007 - 05:10 PM

Cosmic radiation can be one possible cause. But not the only cause.

Going deep under ground would substantially reduce the number of particles of cosmic origin you encounter. But it could introduce loads more radiation from surrounding minerals. Here on the surface, there are places where radon gas comes up from the ground and can reach significant concentrations in buildings. Red clay bricks can contain elements that decay and give off radiation. Perhaps people who live in brick houses shouldn't shoot HD? ;-)

And radiation isn't the only source of tranient hits or noise.





-- J.S.


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#12 Keith Walters

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Posted 01 December 2007 - 05:45 PM

Cosmic radiation can be one possible cause. But not the only cause.

Going deep under ground would substantially reduce the number of particles of cosmic origin you encounter. But it could introduce loads more radiation from surrounding minerals. Here on the surface, there are places where radon gas comes up from the ground and can reach significant concentrations in buildings. Red clay bricks can contain elements that decay and give off radiation. Perhaps people who live in brick houses shouldn't shoot HD? ;-)

And radiation isn't the only source of tranient hits or noise.





-- J.S.

Cosmic Rays are the only type of naturally-occuring radiation where a single particle has enough energy to produce a visible effect on an imaging device.

They are not really "radiation" in the normal sense, they are actually single atoms travelling at enormous speeds through space, apparently produced by supernova explosions. When they hit the Earth's atmosphere most or all of their electrons get stripped off, resulting in a positively-charged fast-moving heavy nucleus that can cause quite a lot of damage when it strikes a solid object. (A lot of damage for a single atom at any rate).

They rarely ever get a chance to do that though, because long before that can happen they will collide with gas molecules in the atmosphere, producing showers of much weaker "secondary" particles, which are what are normally detected as "Cosmic Rays" at ground level. Most of the Earth's atmosphere is contained in the first three miles and so if you go above that, (up a mountain or in an aircraft for example), the number of high-energy cosmic ray impacts increases dramatically.

Naturally ocurring radioactive minerals are only very weakly radioactive, and even weapons-grade uranium 235 or Plutonium is not a significant safety hazard as long as it is a sub-critical mass (that is one too small to sustain a chain reaction). Highly energetic elements such as Radium are extremely dangerous in concentrated form, but the very fact that they are so radioactive means that that vast majority of what was in the Earth's crust decayed to non-radioactive elements millions of years ago.

Although uranium-containing minerals like Pitchblende can fog photogrpahic plates or film, this normally takes a couple of days unless it is ultra-high speed film.

Uranium containing minerals such as granite produce small amounts of Radon, and it tends to be more of a hazard because it is an extremely heavy gas and so tends to accumulate in cellars and similar unventilated places. However, the dangers posed by radon tend to be exaggerated by the media, and it is very unlikely that enough would ever accumulate to damage a camera sensor.

I still think the biggest "radiation" danger would be from someone pointing the camera at the sun with the iris wide open. Although it's hard to "cook" the silicon sensor itself, the Bayer Mask dyes might not be so forgiving!
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#13 Mike Brennan

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Posted 03 December 2007 - 06:26 PM

Cosmic Rays are the only type of naturally-occuring radiation where a single particle has enough energy to produce a visible effect on an imaging device.

They are not really "radiation" in the normal sense, they are actually single atoms travelling at enormous speeds through space, ........
I still think the biggest "radiation" danger would be from someone pointing the camera at the sun with the iris wide open. Although it's hard to "cook" the silicon sensor itself, the Bayer Mask dyes might not be so forgiving!


Thanks for a very informative post Keith!
Does make me realise how dependant we are on our relatively thin atmosphere...


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#14 John Sprung

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Posted 03 December 2007 - 06:35 PM

Cosmic Rays are the only type of naturally-occuring radiation where a single particle has enough energy to produce a visible effect on an imaging device.

Do you mean permanent damage, or just a hit in the signal?



-- J.S.
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#15 John Sprung

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Posted 03 December 2007 - 06:40 PM

what are the other possible causes of transient hits?

You can have thermal noise anywhere in the electronics, plain old wiggle the plug intermittents, tape hits, etc.



-- J.S.
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#16 Keith Walters

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Posted 05 December 2007 - 11:49 PM

Do you mean permanent damage, or just a hit in the signal?


-- J.S.

Both. Once they get outside the Earth's atmosphere, astronauts report seeing regular flashes of light, even with their eyes closed. This is caused by the constant bombardment of unshielded cosmic rays. There is a very real risk that long-duration stays in space (a trip to Mars for example), would greatly accelerate an astronaut's chances of developing cancer in later life. It has been suggested that if they plan to have a family afterwards, it would probably be a good idea for them to use frozen eggs or sperm left behind on earth, rather than risking birth defects in their children.

The most powerful cosmic ray ever detected was estimated to have had the energy equivalent of a .22 rifle bullet leaving the barrel. That's just a single atom by the way, travelling close to the speed of light!

The cosmic ray "event" was detected indirectly, by the enormous shower of secondary particles it generated. Needless to say, if a cosmic ray like that happened to hit the camera sensor it would almost certainly be destroyed. Fortunately, such events are extremely rare - you would be far more likely to get hit by a piece of space junk.

So certainly, if the cosmic ray is energetic enough, it could permanently disable one or more photosites. However it is far more likely to just put a spurious dot on the image.

I wouldn't worry too much; the Pioneer 10 robot probe has been in space since 1972, and as far as we know its on-board computer and radio communications system still work, although about 5 years ago it moved out of radio contact range. Its mission lifetime was expected to be just two years.

Pioneer 6 was launched in 1965 and is still in orbit around the sun and can be contacted as well, although admittedly it's a somewhat less sophisticated probe. It's mission lifetime was supposed to be six months....
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#17 John Sprung

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Posted 06 December 2007 - 02:58 PM

So certainly, if the cosmic ray is energetic enough, it could permanently disable one or more photosites. However it is far more likely to just put a spurious dot on the image.

OK, if I'm understanding this correctly, cosmic rays are not the only thing that can put a tranient defect in the image, but the most energetic of them are the only thing with enough oompf to potentially do permanent damage.




-- J.S.
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#18 Mike Brennan

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Posted 06 December 2007 - 06:12 PM

OK, if I'm understanding this correctly, cosmic rays are not the only thing that can put a tranient defect in the image, but the most energetic of them are the only thing with enough oompf to potentially do permanent damage.




-- J.S.


John and Keith,
Johns statement above may be the most precise description of the effects of cosmic rays.

But I note that gamma rays used to get the bad press from manufacturers for knocking out pixels permanently.

Now its cosmic rays that is said to be doing the damage.

Are the terms interchangeable?




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#19 John Sprung

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Posted 06 December 2007 - 08:57 PM

Are the terms interchangeable?

No, gamma rays are extremely high energy photons, 100 million electron volts and up. Cosmic rays may include some gamma rays, but mostly they're protons and alpha particles (helium nuclei). Cosmic rays hitting the atmosphere can produce gamma rays. There are also gamma ray bursts out in space, but not worth much bother. We're all toast if one happens nearby.



-- J.S.
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#20 Keith Walters

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Posted 06 December 2007 - 09:41 PM

John and Keith,
Johns statement above may be the most precise description of the effects of cosmic rays.

But I note that gamma rays used to get the bad press from manufacturers for knocking out pixels permanently.

Now its cosmic rays that is said to be doing the damage.

Are the terms interchangeable?




Mike Brennan

No. Gamma rays are an entirely diferent thing. In most media statements about radiation, the writers clearly have no idea what they are talking about.

Cosmic rays are atomic nuclei. Gamma radiation is electromagnetic radiation, basically ultra-short wavelength light, and is only produced under extraordinary circumstances.

Visible light such as you see in LEDS or neon tubes is produced by sudden drops in the distance that electrons orbit the nucleus of an atom. An electrical discharge can boost an electron up to a higher "energy level", which is sort of like moving from Earth Orbit to the Orbit of Mars. However unlike planets, electrons can only orbit at certain discrete "heights" (called "Quantum levels"). When an electron falls back to its original quantum level, its extra energy is released as a photon of light. The amount of energy released determines the wavelength of the light produced and since the amount of energy needed to boost an electron to a higher orbital is constant, the light produced tends to be all the same wavelength.

The shortest wavelengths that can be produced by a normal electrical discharges are in the ultraviolet range, because there is a limit to how many levels an electron can be bumped up to before it spontaneously emits a photon.

Gamma rays are produced when an atom is split into two or more pieces, either spontaneously or because it gets hit by a high-speed neutron.

With half the electrons suddenly removed, the original atom's electron shells collapse violently. Basically its outer electrons will fall down a large number of levels producing extremely energetic photons which are known as gamma rays. Because of their high energy content, at high levels Gamma rays are extremely dangerous to biological materials but are not likely to harm electronic equipment. Also gamma ray sources are normally diffuse like a light bulb, so even if they could damage photosites in a TV camera, it would be an "all-or-nothing" situation.

The only significant sources of Gamma rays that exist on the planet are radium or cobalt 60, (which is made artifically in nuclear reactors). Neither substance is likely to encountered on a day-to-day basis, as they are extremely dangerous and restricted to special uses.

I think some of these stories have come from the efforts of memory chip manufacturers to keep radioactive contaminants out of the epoxy materials used to encapsulate their silicon chips. They have to take great care to avoid contamination by carbon-14 and Potassium-40. Although these only produce weak alpha and beta radiation, in a memory cell which may be only 50 nanometres square,a single particle of one of those can cause a fatal error in a computer program!
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