[d2n-analysis-talk] SAMC and Acceptance Cut Studies

[Brad Sawatzky]

On Wed, 20 Apr 2011, David Flay wrote:

> On Wed, Apr 20, 2011 at 2:56 PM, Brad Sawatzky <brads at jlab.org> wrote:

> > I don't understand the losses for very tight cuts shown on slide 6
> > though.  If you point a beam of particles right along the central
> > axis of the spectrometer, and with p = p_0, then 100% should pass
> > through to the focal plane....   Is this some straggling effect due
> > to scatters between the generation point and the Q1 vacuum window?
> > What happens if everything is vacuum (no windows, no glass target
> > cell, etc)?
> 
> On slide 6, it shows that the losses aren't occurring until the dipole
> exit, not Q1 -- maybe I'm not following concerning the straggling
> effect before Q1 in this case?

Right, but if all your particles are really running right down the HRS
sweet spot (as the cuts would imply), then 100% of them should reach the
focal plane.

> > I think what you should be doing is tightly constraining the
> > generated particle kinematic distribution (ie. the black lines on
> > slide 4).
> 
> Do you mean slide 5? (Aperture Cut Study slide 2)

Nope, I meant slide 4 "Aperture Cut Study slide (1)".  If my
understanding is correct, then the black distribution reflects the
particle momenta as generated inside the target cell.  My suggestion is
to set things up so 100% of the generated particles are pointing at the
middle of Q1 and have momentum = p_0.  Every one of those particles
should make it to the focal plane (in a vacuum, anyway).

-- Brad

-- 
Brad Sawatzky, PhD <brads at jlab.org>  -<>-  Jefferson Lab / Hall C / C111
Ph: 757-269-5947  -<>-  Fax: 757-269-5235  -<>- Pager: brads-page at jlab.org
The most exciting phrase to hear in science, the one that heralds new
  discoveries, is not "Eureka!" but "That's funny..."   -- Isaac Asimov