RE: [Brahms-l] phi->kk analysis (Run4 AuAu dataset)

Dear Truls,

Thank you for your comments..

Rightnow I am working with kaon PID. I shall post the results once it is done..

yes, we can handle lambdas also with the same machinary...

Best regards,
Dipali




-----Original Message-----
From: Truls Martin Larsen [mailto:trulsml_at_nbi.dk]
Sent: Tue 8/1/2006 4:12 AM
To: Pal, Dipali
Subject: RE: [Brahms-l] phi->kk analysis (Run4 AuAu dataset)
 
Hi,

sounds good!!! The binning really makes things better/convinces me that
there really is a peak there... I don't know which one is the best
though 2MeV maybe...??? One more comment added below...

On Mon, 2006-07-31 at 14:54 -0500, Pal, Dipali wrote:
> Dear Truls,
>  
> Thank you for your comments.
> 
> 
> >I have a couple of questions:
> >With mean bias, do you mean that you have looked at only trigger 4
> >events (ZDC coincidence)? In such case there is a lot more tracks when
> >you look at trigger 3 (BB-TrMRS-TOFW coincidence). You should be very
> >carefull if you want to mix triggers in your event sample. Normalization
> >will get tricky and you must be extremely carefull not to double
> >count...
> 
>  
> I used MRS triggers (trig 3) only for this analysis to avoid confusion with other triggers at the time of event mixing.
> 
> >About the phi "point": I see one point, which is about 2.5 sigma away
> >from the background... at 1.047 and 1.055 there is also 2 points about
> >2-3 sigma away from the background. What are they? just background? 
>  
> The points around 1.05 GeV, may arise from mis-identified pions or from track pairs with wrong timing. I tried to eliminate the later by requiring that no two tracks in an event share the same hit at a TOF slat. For the first, I need to  choose better PID. 
> I shall, however, do a deeper investigation on both.
>  
> >I
> >don't doubt that there are phis in the event sample, and you have
> >probably found them all, it would be good to have more points to fit you
> >gaussian to... what about the binning? 1 or 2 MeV perhaps? or is it just
> >more messy?
> 
>  
> I generated spectra for 1 MeV/c^2 and 2 MeV/c^2 mass bins. You can have a look at them 
> http://www4.rcf.bnl.gov/~pald/phiKK/inv_40_1050_1MeV.gif <http://www4.rcf.bnl.gov/~pald/phiKK/inv_40_1050_1MeV.gif> 
> http://www4.rcf.bnl.gov/~pald/phiKK/inv_40_1050_2MeV.gif <http://www4.rcf.bnl.gov/~pald/phiKK/inv_40_1050_2MeV.gif> 
>  
> I find that the line shape parameters, centroid and width, in three mass bins are:
>  
> mass bin                    centroid (GeV/c^2)                         width (MeV/c^2)
> 1 MeV/c^2                    1.022 +/- 0.001                               2.2 +/- 3.5
> 2 MeV/c^2                    1.022 +/- 0.001                               3.3 +/- 2.0
> 3 MeV/c^2                    1.022 +/- 0.001                               2.8 +/- 2.1
>  
> There is no change in centroid and no significant change in width if we change mass bining.
> 
> >About your selection of K's:
> >The calibration in the database should be reasonable.
> >calibrations can be browsed here:
> >http://brahms-web.brahms.bnl.gov/daq-cgi-bin/cgiCalibrationDB.perl <https://owa.ku.edu/exchweb/bin/redir.asp?URL=http://brahms-web.brahms.bnl.gov/daq-cgi-bin/cgiCalibrationDB.perl> 
> >How does you mass^2 vs mometum look like? is it skewed?
> >What kind of functions do you use for the pid cut?
> 
> For generating this first spectrum, I simply analyzed tracks through TPFW with
> 0.2 < mass^2 < 0.3 for all momenta. This will be replaced with a proper PID function.

When you do kaon PID with TOFW you should not go above 2GeV/c in
momentum... (this is a design thing...)... this could maybe clean up
your background a little.


>  
> Best regards,
> Dipali
> 

Looks like you got some really good analysis going!!! What about
lambdas? Should not be too hard to get those too, with the software you
have, after you get a handle on the phi...

Cheers,
	Truls

> ________________________________
> 
> From: Truls Martin Larsen [mailto:trulsml_at_nbi.dk]
> Sent: Mon 7/31/2006 3:25 AM
> To: Pal, Dipali
> Subject: Re: [Brahms-l] phi->kk analysis (Run4 AuAu dataset)
> 
> 
> 
> Hi Dipali,
> 
> I have a couple of questions:
> With mean bias, do you mean that you have looked at only trigger 4
> events (ZDC coincidence)? In such case there is a lot more tracks when
> you look at trigger 3 (BB-TrMRS-TOFW coincidence). You should be very
> carefull if you want to mix triggers in your event sample. Normalization
> will get tricky and you must be extremely carefull not to double
> count...
> 
> About the phi "point": I see one point, which is about 2.5 sigma away
> from the background... at 1.047 and 1.055 there is also 2 points about
> 2-3 sigma away from the background. What are they? just background? I
> don't doubt that there are phis in the event sample, and you have
> probably found them all, it would be good to have more points to fit you
> gaussian to... what about the binning? 1 or 2 MeV perhaps? or is it just
> more messy?
> 
> About your selection of K's:
> The calibration in the database should be reasonable.
> calibrations can be browsed here:
> http://brahms-web.brahms.bnl.gov/daq-cgi-bin/cgiCalibrationDB.perl
> How does you mass^2 vs mometum look like? is it skewed?
> What kind of functions do you use for the pid cut?
> 
> Cheers,
>         Truls
>        
> PS: If you have questions about the banapp stuff, I'm typically the one
> to ask, as I "volunteered" to put it together...
> 
> 
> On Thu, 2006-07-27 at 12:37 -0500, Pal, Dipali wrote:
> > Dear All,
> >
> > I have made some studies on phi->KK analysis using BRAHMS MRS.
> > As you can see from my attached slides (ppt file), we clear
> > see phi meson peak for min bias run4 Au+Au  dataset at 200 GeV.
> > We shall extract min bias dN/dy soon.
> >
> > Please let me know your comments and suggestions.
> >
> > Best regards,
> > Dipali
> >
> > _______________________________________________
> > Brahms-l mailing list
> > Brahms-l_at_lists.bnl.gov
> > http://lists.bnl.gov/mailman/listinfo/brahms-l
> 
> 
> 


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