Re: back?

[Brendan Kiburg <kiburg@npl.uiuc.edu>]

Hi Peter,
  In addition to Fred's plot, I have done a HV scan for the muPC and
added it to my elog that was started before dinner.  I think it shows that
2300V is too low, while anything higher than 2400V unecessarily cuts
events due to electron efficiency.  As such I have changed the muPC
voltage to 2400V.  Please see my elog for details.

Brendan

On Mon, 5 Dec 2005, Frederick Gray wrote:

> On Sun, Dec 04, 2005 at 10:39:37PM -0600, Peter Kammel wrote:
> > Thanks Steve,
> > 
> > See my elog:408 (mainly for Fred). 
> > 
> > See you tomorrow.
> > 
> 
> Hi, Peter,
> 
> Brendan and I now think that we understand what's going on here.  If you
> have a look at the current trend plot (sample attached), you will see a
> new set of data points just above the green muSC-muPC1 line.   The three
> top curves are then:
> 
> Red: muSC (muSC PP)
> Medium blue: muSC (muSC-muPC1 PP)   ** new point **
> Green: muSC-muPC1 (muSC-muPC1 PP)
> 
> Events are lost by the added pileup protection of the muPC, not by a large 
> inefficiency.   As the beam rate increases, this effect becomes larger.
> Also, as the high voltage is increased, the muPC becomes more sensitive to
> electrons, so more events are lost to pileup protection.
> 
> -- Fred
> 
> -- Fred Gray / Visiting Postdoctoral Researcher                 --
> -- Department of Physics / University of California, Berkeley   --
> -- fegray@berkeley.edu / phone 510-642-2438 / fax 510-642-9811  --
>