Thanks for the comment Joanna,

>  In STAR (and Phenix) "bad" Yellow bunches collide with low intensity
> Blue bunches or abort gap ( bunches became bad due to a collision with low
> intensity bunches? ).

I could only say that this cannot be happened just by a coincidence, and 
the fact that the bad bunches are always sitting at 16-20 and 36-40 supports 
this assumption. (Does C-AD people already know this?)

> So, removing 2 groups of Yellow and 2 groups of Blue bunches
> results in removing only one group of bunch crossings 
> in STAR (and PHENIX).

Yes. The experiments need to sacrifice only 5-bunches instead of 10.
And I believe we should discard them from all the runs, even if their 
distributions look normal at times.

  -- Osamu

From: Joanna Kiryluk <joanna@physics.ucla.edu>
Subject: Re: notes on RHIC polarimeter meeting
Date: Mon, 12 Aug 2002 11:21:40 -0700 (PDT)

> 
> 
> Hello Osamu, 
> Just realized I should have replied to your e-mail, but forgot: 
> 
> > During the meeting today, we were aware that the WCM (or specific 
> > luminosity dist of polarimeter) is wrong for yellow. And we thought
> > that I(Osamu) had made mistakes to use the blue WCM in the yellow analysis.
> > 
> > But it turned out that the plot I showed was rael, it means "the yellow
> > had the bad 5 bunches as well".
> > Please take a look at follwing two kinds of plots and confirm this fact.
> 
> 
> What we observe in STAR: 
> - specific luminosity: there is a group of a few bunches:
> ( bunch crossing 36-40, i.e. 
> Yellow bunches 36-40 collided with Blue bunches 16-20)
> which has specific luminosity smaller or bigger than 
> for the other bunch crossings. 
> 
> For example fill 2251:
> www.physics.ucla.edu/~joanna/Fill2251/Run3018025_WCM.ps  
> 
> to be compared with your plots for Fill 2251, run 755 (Blue) 757 (Yellow):
> http://ccjsun.riken.go.jp/~jinnai3/polarimeter/bunch_sel/Specific/index.html
> http://spin.riken.bnl.gov/exp/pcpol/2001/Bunch_web/index.html
> 
> 
> Both STAR and CNI data (specific luminosity) are consistent. 
> 
> 
> The problem with bunch crossings 36-40 I interpreted as originating from 
> Blue beam ( two groups of weak bunches from intensity plot). 
> Yellow looked perfectly "normal" to me, i.e. intensity distribution 
> was flat.
>  
> >From your(Osamu's) plot however (yellow and blue specific luminosities:
> specific luminosity for yellow has groups of bad bunches although 
> intensity distribution is flat, specific luminosity for Blue is flat 
> although intensity has 2 groups of weak bunches) one can
> see, that problematic are Yellow bunches. 
>  In STAR (and Phenix) "bad" Yellow bunches collide with low intensity
> Blue bunches or abort gap ( bunches became bad due to a collision with low
> intensity bunches? ).
> 
> So, removing 2 groups of Yellow and 2 groups of Blue bunches
> results in removing only one group of bunch crossings 
> in STAR (and PHENIX).
> 
>   Regards, Joanna 
>  
> 
> 
> 
> 
> 
>