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Aaron,<br>
<br>
It has been some years since I worked at the Nuclear Physics
Lab at Rutgers University (with an 8MeV Van De Graff particle
accelerator), but I will relay what I know. 10 keV x-rays are
barely able to make it past the chamber walls. Of course, this
depends upon the proximity of the gun to the chamber walls, their
thickness, and the material they are constructed from. It is always
good to confirm this with a Geiger Counter. <br>
<br>
Over years that I have been here at Princeton, occasionally
someone from our own EHS is sent over to measure the amount of
radiation being produced by our tools, and they have never been able
to get a reading over background. You would get a larger dose of
radiation while standing in front of the bananas (K40) at Shop Rite,
sleeping next to someone (C14), living in Denver, Co, or flying in
an airplane. I don't mean to belittle their concern; when involved
in any research that involves the possibility of radiation exposure,
keeping track of your cumulative dosage is important. In short, I
am generally not concerned with anything lower than 10keV. <br>
<br>
Regards,<br>
<br>
Joe Palmer<br>
<br>
<div class="moz-cite-prefix">On 5/27/2020 11:21 PM, Aaron Hryciw
wrote:<br>
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<div>Dear colleagues,<br>
<br>
One of the users in our open-access facility recently
expressed concern about x-ray production in electron-beam
evaporation systems. Since the typical acceleration voltage
in our e-beam systems is 7–10 kV, he was concerned that
bremsstrahlung and characteristic x-rays would be generated
during deposition, with a maximum energy of 7–10 keV (soft to
hard x-rays), and that these x-rays would pose a health and
safety hazard to an operator standing next to the viewport for
~30 minutes.<br>
<br>
A literature search yielded a few reports describing radiation
damage to sensitive devices from x-rays produced during an
e-beam metallization step, but I did not find any mention of
related health and safety considerations. While some x-rays
are undoubtedly produced, presumably there are reasons why
they are not hazardous to an operator (e.g., perhaps total
x-ray output is very small, majority of x-ray spectrum is low
energy, x-rays do not penetrate stainless steel chamber walls
or viewport windows, etc.). I would like to answer this user
with specific physical arguments as to why the hazard is
insignificant, however, so any advice you could offer to this
end would be greatly appreciated. Many thanks.<br>
<br>
Cheers, <br>
<br>
– Aaron<br>
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<pre class="moz-signature" cols="72">--
Joseph E. Palmer
Chief of Operations for the MNFL
PRISM, Princeton University
Contact:
Office (Tuesdays and Thursdays): 609-258-4706
Cell: 609-731-8962</pre>
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