Not long ago, while argueing ver whether some of the Images we are seeing from SOHO might actually be a solid object or just Cosmic Rays, I sort of
accepted a challange to show that they might not be cosmic rays.
I've written anarticle on this, but it is rather large for this format. However if anyone is interested;
Here is a link to it.
I can't go into uch detail here, but I do highly recommend that everyone read these two articles, even IF you don't read mine.
1. Cosmic Rays
2. CCD Arrays
These will help greatly in understanding all this.
In figure 1 we have a streak that enters from the edge of the array, looses energy and ends after several hundred pixels.
This is the trace or trail of a cosmic ray that enters the array parallel to the plane of the array and perhaps only a few tenths of a
nanometer below the surface. This ray had enough energy to penetrate several hundred pixels, or cells before running out of energy. The few
dots , seemingly at the end of the streak, are actually other cosmic ray strikes.
Figure 2 shows us another cosmic ray streak, though this time it is two with an interesting alignment.
The cosmic ray labeled cosmic ray 2 while appearing to be an extension of the longer one likely isnt. The reason is that the first ray has lost
energy and ends rather abruptly some number of pixels before the second starts. It is highly unlikely that the cosmic ray has somehow gained
energy and was able t continue on in the second trace.
It must also be considered that streaks like these can only be made in a rather limited number of circumstances.
1. A cosmic ray whose vector is parallel to the plane of the CCD, and strikes and enters the side in such a manner that it penetrates the device
at a point where it can transfer a charge to the imaging cells.
2. A cosmic ray whose vector is not parallel, but within 4 or 5 degrees of parallel; thus leaving a streak that does not begin at any edge,
yet continues for several pixels. The number of pixels illuminated being determined by the angles of that vector.
3. A large number of cosmic rays that happen to be so aligned to each other, that they paint a line or streak.
This style I believe to be single cosmic rays making each trace.
In figure 3 we see two more cosmic ray streaks, the rays appear to be moving from left to right.
Nearly all of the samples of these Cosmic Ray streaks Ive looked at seem to exhibit similar properties. In this case the trailing edge; seems to
trail off or fade. This can be cause by the cosmic ray penetrating the CCD below the level of its depletion region, yet still imparting some
energy to the cell.
And, of course, all the bright isolated dots are single cosmic rays that enter at an angle greater than what will support a streak. Also, cosmic
rays striking the CCD at angles of less than 86 degrees (or so), May, if they strike near the edge of a cell, illuminate two adjacent cells.
The reader should have noticed that around most of the single pixel hits and around the streaks there appears to be a slight bloom. This
is caused by charge bleeding from one cell to an adjacent one. These cells are well insulated electrically, but, the insulator between the cells
is Silicon Dioxide, and, it too can make for a fair dielectric, and may thus allow coupling of charge to adjacent cells.
It also important to understand the sensing portion of this device; for those who read the link, you will remember, a charge is coupled when a
photon or electric charge is delivered to the surface of the device. Directly under these photon / charge sensing plates is what is termed the
depletion region. This is semiconductor material that has its PN junctions reverse biased, this causes a condition known as cutoff,
a state where only minimal current is allowed (in these kind of devices, that current is almost 0). The residual current is considered noise. So,
this depletion region, the (semi)conductor above it, and the semiconductor below it form a capacitor with a dielectric of less than 100 nanometers
(up to 100 nm must be considered due to SOHOs age; Circa 1995). All of the oblique angled cosmic rays must deliver all their charge within this
Now let us consider another class of SOHO image; the so-called massive UFO near the Sun.
Actually this class of image is rather unique, in that every instance requires several (more than one cosmic ray to construct it, and each of these
cosmic rays must occur within a 12 second window, that is available once every 12 minutes.
In figure 4 we have two intersecting cosmic rays, both traveling toward a bright spot where they intersect. It should be noticed that this bright
spot is also the terminus of both vectors. There is very little about this image that would suggest that this wasnt cosmic rays.
In Figure 5 we see much the same, but with an added feature.
The image looks straightforward enough, two apparent cosmic rays radiating out.
However, there is that central bit of pixels that is bothersome; it forms a straight line some 10 or so pixels in length. It begins and ends abruptly
and has no halo despite its apparent intensity. In as much as it does not seem to behave like other cosmic recordings; it is very unlikely to be a
In Figure 6 we have yet another interesting image.
This time the cosmic rays are converging as in Figure 4, I took the liberty of extending the vectors so that we may see where they might have
intersected (thin Yellow lines). Nothing special about this except for the blob just above the intersection of the vectors; not to sure what
to make of it, it could be a distant celestial object, a group of cosmic rays (doubtful), or most anything. It has some of the characteristics of
cosmic ray strikes, but, the size might suggest something else.
There is a single fundamental difference between the first set of images and the second. That is; in all three of the second set of images there are
two cosmic rays with intersecting vectors. This makes the whole proposition much less tenable. From two separate sources a cosmic ray must be emitted
with such timing that it intersects another on, or, very near the sensing plates of the CCD, either before or just after the actual intersection
point, and within the same 12 second _ The probability of this, despite the sheer quantity of cosmic rays is massively small.
****END PART ONE****
edit on 7-8-2012 by AnthraAndromda because: (no reason given)