[esa-t474] Your submission (fwd)

[Eric Torrence]

Hi Mark,

    I think Mike has already given some good pointers
on this, but just to reiterate it should be clearly
stated that measuring the mean beam energy before
collisions is a necessary (but certainly not sufficient)
part of determining the collision spectrum needed for
the ILC program.  For both direct reconstruction like
M_H and threshold scans like M_t, the peak of the
spectrum is the most important feature.  There are
plenty of corrections, including energy loss in magnets
and beamstrahlung, which need to be applied, but without
a calibrated mean beam energy measurement you have no hope.

Regards,
-Eric

On Dec 14, 2007, at 3:18 AM, Mark Slater wrote:

> Dear All,
>
> Here are the first comments from the reviewer. Does anyone have a good
> answer to this?
>
> Thanks,
>
> Mark
>
> ---------- Forwarded message ----------
> Date: Thu, 13 Dec 2007 21:08:00 -0000
> From: nim at lbl.gov
> To: slater at hep.phy.cam.ac.uk
> Subject: Your submission
>
> Nuclear Inst. and Methods in Physics Research, A
> Title: Cavity BPM System Tests for the ILC Energy Spectrometer
>
> Dear Dr. Slater,
>
> Thank you for your recent submission to Nuclear Inst. and Methods in
> Physics Research, A.
>
> Before proceeding further with the review process, I would like you to
> address in detail the following issue.  Beamstahlung will spread the
> energy of the electrons and positrons at the collision point by an  
> amount
> far greater than the precision of the instrument that you propose.  
> Indeed,
> for the purposes of data analysis new approaches, such as particle  
> flow
> analysis, must be developed because one cannot balance momentum in the
> beam direction. Your treatment of this issue should speak to how the
> information from the proposed instrument would be used as an input  
> to the
> new physics analysis approaches.
>
> Sincerely,
>
> William A. Barletta
> Editor
> Nuclear Inst. and Methods in Physics Research, A
>
>
> _______________________________________________
> esa-t474 mailing list
> esa-t474 at hep.ucl.ac.uk
> https://mail.hep.ucl.ac.uk/mailman/listinfo/esa-t474
>