Inspection with an electron microscope II

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Stone kapton straw

Pristine

Stone kapton straw that was never used (500um scale).
Stone kapton straw that was never used (20um scale).
Stone kapton straw that was never used (5um scale).

The relative X-ray analysis of a normal area gave three peaks C, Al, and O. The magnitude of the peaks compared as C > Al > O. White spots are Ca = C = O > Al > P

Under source (irradiated)

Stone kapton straw that was irradiated (500um scale).
Stone kapton straw that was irradiated (20um scale).
Stone kapton straw that was irradiated (5um scale).

The relative X-ray analysis of a normal area gave three peaks C, Al, and O. The magnitude of the peaks compared as C > Al > O . The X-ray analysis of a dark spot gave C = 0 > Al. Also the darker the spot the more O present.


3 years under voltage (big prototype)

Stone kapton straw that was used for three years (500um scale).
Stone kapton straw that was used for three years (20um scale).
Stone kapton straw that was used for three years (5um scale).

The relative X-ray analysis of a normal area gave three peaks C, Al, and O. The magnitude of the peaks compared as C > Al > O, also the darker areas gave the same relative C > Al > O.


Lamina thin straw

Lamina-thin straw that was irradiated (20um scale).

The relative X-ray analysis of a normal area (light gray) gave three peaks C, Al, and O. The magnitude of the peaks compared as Al > C > O. The dark spots showed O > Al > C or O = Al > C . White spots are Ca = C = O > Al > P

Lamina thick straw

Lamina-thick straw that was irradiated (20um scale).

The relative X-ray analysis of a normal area gave one peak: Al. The white dots are Fe


Conclusion at 2am

It might be that the dark gray areas seen on the kapton and Lamina-thin straws after radiation are due to the same process. They appear to be a higher concentration of (Al?)O indirectly induced by radiation. This process takes time and it looks that after 3 years of normal (low radiation) operation of a stone kapton straw a difference (darker gray areas) can be observed with the EM but not with the X-ray analysis. As after an equivalent of 44 years of radiation the straw (Lamina-thin and kapton) shows a big increase in dark areas or "black pits" the straw is still operational. It hints that although the aLuminum layer of the Lamina-thin straw "degrades" after being exposed to radiation, this process is too slow to harm operation during the running period of GlueX. The Lamina-thick straw does not show any effect at all.