RE: low momentum tail from wire hits?

["David W Hertzog" <hertzog@uiuc.edu>]

Bernhard,
	Wow, a very important study.  Thanks.  Let's go through it (all
of us) at the next teleconf.  There are some clear subtle issues with
the GEANT as you point out, which makes it a bit confusing for the
reader to follow. 

	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.

	Dave

-----Original Message-----
From: Bernhard Lauss [mailto:lauss@berkeley.edu] 
Sent: Friday, January 27, 2006 6:29 PM
To: Peter Kammel
Cc: Dan Chitwood; David Webber; David W. Hertzog
Subject: Re: low momentum tail from wire hits?



Dear Dan, Peter  et al

I have modified and run my GEANT model now several times
following your suggested MuLAN micromodel miniturization,
and went then back to a full model with the results shown
in the attached note.
Looking closer however made me real wonder what GEANT does with
decay in flights (section 2.2) and I am not sure what one should
really conclude from that.

However the effect of the EMC wires on the muon energy distribution
at the target seem to be trustworthy to me.


		Have a nice weekend

				Bernhard





*******************************************************************
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
*******************************************************************

On Wed, 18 Jan 2006, Peter Kammel wrote:

> Dear Dan,
>
> Let's call Bernhard at a suitable time tomorrow and discuss the
> issue with him.
>
> Regards
>
> Peter
>
> On Tue, 17 Jan 2006, Dan Chitwood wrote:
>
> > This is a very basic calculation and measurement, but it looks like
the
> > number of low momentum hits seen with the beam is at least on the
same
> > order of magnitude as one would expect from wire collisions.
> > Looking at a few of the momentum distributions, I found a ratio, R,
of
> > low momentum to normal stops of somewhere between 0.03 and 0.04
> > If I take the wire to empty space area ratio for a wire chamber and
set
> > it equal to R, I find the formula 2W/L = R where W is the width of
the
> > wires and L is the inter-wire spacing.  This assumes nothing about
the
> > difference between path lengths through the wire.  I don't know the
> > specs for the muPC, but these numbers seem consistent with the EMC
where
> > I believe L=1 mm and W~0.02 mm.
> >
> > -- Dan
> >
>
>