Email from Dave:

Date: Thu, 23 Sep 2004 21:53:04 -0400 (EDT)
From: Dave Mack 
To: Jim Birchall 
Cc: Juliette Mammei , Roger Carlini ,
     Klaus Grimm , Mark Pitt ,
     Neven Simicevic , Greg Smith ,
     Allena Opper , Richard Jones ,
     Norman Morgan , Mike Finn ,
     David Armstrong , Yongguang Liang ,
     Shelley Page , Tony Forest ,
     Dave Mack 
Subject: Re: Collimator material


	Jim et al,

	If this material is for the acceptance-defining edges of the
collimator, then Peter Bosted suggested we develop a specification for
magnetic contaminants. We are much less susceptible to this potential
problem than E158, which had lots of collimation imbedded in strong
magnetic fields. I told Peter there were no bulk ferromagnetics in the
scattered beam path, the collimator is sitting in a "weak" magnetic field,
and our spectrometer will reject events with large energy loss. But
"quantify before you buy" is probably good policy. 

	Roger will respond that such an effect would be "really, really
little" and I'll respond that the effect we're measuring is "realy, really
little", so let's just skip that round of emails. If someone can tell me
the order of magnitude of the field strength (mini-torus + big torus) at
the defining collimator then I'll work with one of our many Geant experts
to develop the contamination specification (before we buy).

	grins,

	Dave
	





On Thu, 23 Sep 2004, Jim Birchall wrote:

> Here's the link to info on the Cu-Pb alloy Paul Brindza found for the 
> collimator material. It's 70% Cu by weight, 25% Pb, 5% Sn, density 9300 
> kg/m3.
> 
> Jim
> 
> http://www.anchorbronze.com/c94300.htm
> 
>