Page History
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| Pixels | Peaks | Mean | Error | RMS |
|---|---|---|---|---|
| 1 | 7164 | 140.24 | 0.09 | 7.45 |
| 2 | 14926 | 142.54 | 0.07 | 8.24 |
| 3 | 4354 | 141.53 | 0.17 | 11.44 |
| 4 | 2898 | 146.58 | 0.18 | 9.70 |
Lining
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Up and Recombining Pixel Distributions
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As can be seen in the table above, there is a noticeable difference in the means of the energy distributions for each number of pixels which, ideally, shouldn't exist. Furthermore, the errors on the mean cannot account for this difference. One theory is that the larger peaks (the ones with more pixels) end up adding in more noise to the total energy of the photon thus shifting it to a slightly higher energy. If such is the case, one remedy would be to shift each distribution so that their peaks fall on the same bin. This was done by using the average of the four bins where the peaks existed as the new bin for the peaks. Below is the result compared to the normal distribution shown in the first graph on this page. As can be seen, the difference is very slight; the distribution is slightly sharper for the shifted data, but not by very much.
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| Mean | Error | RMS | |
|---|---|---|---|
| Shifted | 141.55 | 0.06 | 8.59 |
| Unshifted | 142.06 | 0.06 | 8.72 |
Different Shapes of 3 Pixel Peaks
Three pixel peaks are interesting peaks because they seem like they are extremely unlikely to happen, or at least less likely than what we see. To understand which shape is being discussed, the following names were chosen to represent the different possible shapes:
| Name | Description |
|---|---|
| C | Both non-max pixels are adjacent to the max pixel but not opposite each other |
| L | One non-max pixel is adjacent to the max pixel while the second is adjacent to the first so as to not form a straight line |
| I | A straight line where the middle pixel is the maxpixel |
| Idot | A straight line where one of the end pixels is the max pixel |
| HS | (Hockey Stick) An Idot where the pixel furthest from the max pixel is shifted one pixel in either the positive or negative directions perpendicular to the original line |
| NaS | (Not a Shape) Any shape that is not described by any of the above shapes (This included peaks where no non-max pixel is adjacent to the max pixel |
The distribution of 3 pixel peaks of these shapes is shown below out of a total of 4069 peaks for the V1 algorithm:
| Shape | Peaks |
|---|---|
| C | 3449 |
| L | 434 |
| I | 71 |
| Idot | 0 |
| HS | 115 |
| NaS | 0 |
It makes sense that there are zero Idot peaks. This is because the rank is 1 and therefore it is impossible to have a line 3 pixels long that begins with the max peak; it would exceed the boundary from the rank. It is also understandable that there are no NaS because of the small number of possibilities to have no adjacent pixels to the max pixel. For the L shapes, some number of them had a pixel exceeding the high threshold on the pixel not adjacent to the max pixel which would represent two separate photons. A similar situation was also seen with the I shape (both ends of the I exceeded the high threshold). Their energy distribution is shown below.
The peak for the L shape at about 280 is a clear indication that there are two photon peaks that appear as the L shape.
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