RE: low momentum tail from wire hits?

[Bernhard Lauss <lauss@berkeley.edu>]

Dear all,


Thanks to all of you for your helpful comments.
I will keep working a bit more on that problem.
Here are some answers.

Dave:
>One idea. You can put in a think tungsten sheet (not actual
>wires) and see how many of the muons stop in the helium (I guess
>stopping is tricky here).  We can then use geometry to compute how often
>the wires do that.

I will do that, too.


Dan:
<First, it would be nice to see if you can reproduce stopping
<distribution results in air from the use of the mucap setup.  This would
<imply changing the EMC to match the specs of the muPC, removing the
<helium bag for air, and either removing the target or moving it
<downstream.  In order to make a claim about the muon stops in Helium, I
<would like to know that we can reproduce real results in air.

I will try to reproduce the air scans, takes a while.
I guess the muPC and EMC are not very different anymore,
besides the wire gaps of 1 mm vs 2 mm.
Dan, do you happen to have the full material budget for the EMC.


>Second, I think the fractional cross section for 25 micron wires with 1
>mm spacing is closer to 0.05 than the 0.0006 you quoted.  Each wire has
>a cross section of 0.025mm*1mm giving a sum of 0.05 mm^2.  I think you
>may have only calculated the overlap region of the two wires (0.025mm)^2
>= 0.00625 mm^2, but this is a negligible correction to the total cross
>section and is only relevant in that the muons that do pass have to go
>through twice as much material.   I don't think this affects any of your
>conclusions, but I think it is important to note that we expect ~1/20
>muons to hit a wire.

Correct, I thought that 2 wire hits are much more likeley to stop
in Helium therefore I used that cross-section. Otherwise I agree that
1/20 of all muons will hit a single wire.



David:
>in figure 5, what is the arrangement of the two
>wires?  Are the perpendicular to each other at different z, as they are
>in the wire chamber?

The wires are positioned in parallel, conseqently all muons
pass through both wires, therefore the second peak is
as high as the first one


>if you want this posted on the notes page,
>let me know.

Let me do some more work on it before we post it.



	  best regards
		and thanks for suggesting more work :)


                 Bernhard





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Bernhard Lauss                 E-Mail: lauss@socrates.berkeley.edu
Physics Department
366 LeConte Hall
University of California @ Berkeley
Berkeley, CA 94720                             Tel: (510)-642 4057
United States                                  Fax: (510)-642 9811
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