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Impressive study.<br>
<br>
My question is whether we can have the accelerator turn down the
wick enough so that the TAC rate is acceptable. Note that to do what
we want to do, namely measure the "tagging ratio", knowledge of the
absolute flux is not required from any source other than the TAC
itself. The electron current needs to be stable, but it does not
need to be well known. If low current can be delivered, then clearly
the time and effort toward non-standard collimation could be saved.<br>
<br>
<div class="moz-cite-prefix">On 01/21/2016 09:19 AM, Richard Jones
wrote:<br>
</div>
<blockquote
cite="mid:CABfxa3TLxz5nE2rqucBCmTjz1eYbs=N8Lonia==d6nZjOX1fcw@mail.gmail.com"
type="cite">
<div dir="ltr">Dear colleagues,
<div><br>
</div>
<div>Yesterday I promised to do a quick MC study to determine
what a steel collimator insert with an aperture adjusted to
allow the TAC to run safely with a 10 nA electron beam and a
2e-5 radlen radiator. The answers are given in a quick tech
note that I link below. I am not done writing it yet, so if
there are plots or results that you would like to see added
please let me know. The bottom line is that steel will work
just fine, and it only needs to be 15 cm long. The inner
aperture diameter should be 1.1 mm. In response to Tim's
question, tungsten would be better of course, but steel seems
to work just fine and might be easier to work with.</div>
<div><br>
</div>
<div><a moz-do-not-send="true"
href="http://zeus.phys.uconn.edu/halld/collim-1-2016/collim-1-2016.pdf">http://zeus.phys.uconn.edu/halld/collim-1-2016/collim-1-2016.pdf</a><br>
</div>
<div><br>
</div>
<div>-Richard Jones</div>
</div>
<div class="gmail_extra"><br>
<div class="gmail_quote">On Thu, Jan 21, 2016 at 7:55 AM,
Timothy Whitlatch <span dir="ltr"><<a
moz-do-not-send="true" href="mailto:whitey@jlab.org"
target="_blank"><a class="moz-txt-link-abbreviated" href="mailto:whitey@jlab.org">whitey@jlab.org</a></a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">
<div>
<div
style="font-family:arial,helvetica,sans-serif;font-size:12pt;color:#000000">
<div>Hi All,<br>
</div>
<div><br>
</div>
<div>In speaking with the machine shop, we can take a
precision ground tungsten rod and cut it in half long
wise with wire EDM.<br>
</div>
<div>We can then cut a 1.5mm diameter half hole in each
half.<br>
</div>
<div><br>
</div>
<div>Both halves would then be put in the 5mm primary
collimator hole together giving us a 1.5mm hole (or
what diameter is needed).<br>
</div>
<div><br>
</div>
<div>Tim Whitlatch<br>
Hall D Engineer<br>
Jefferson Lab<br>
600 KELVIN DR STE 5<br>
Newport News, VA 23606-4468 <br>
<a moz-do-not-send="true" href="tel:757-269-5087"
value="+17572695087" target="_blank">757-269-5087</a></div>
</div>
</div>
</blockquote>
</div>
<br>
</div>
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