[Brahms-l] Brahms Minutes 30 March 07

BRAHMS Analysis Meeting Friday 30 March 2007

Present: Dipali, Selemon, Michael, Ramiro, Hongyan, Truls, JH, Steve,  
Kris, Flemming


Agenda: http://indico.cern.ch/conferenceDisplay.py?confId=14423
09:30 	Status of the 62 Gev analysis, pp, CuCu and AuAu. Truls Martin  
Larsen
10:00 	p+p @ 62 GeV analysis Natalia Katrynska updated from Krakow

Action Items:
1) Truls should check if he is using dead slats in maps.
2) Correcting for the trigger bias for pp_at_62GeV is vital.  A  
pt=1.5GeV particle
at y=3 takes half the momentum and causes a rapidity gap. This leaves no
particles in the CC counters. Flemming is writing a note on this  
which he will distribute and then Truls and Natalyia will impliment  
this in there analysis.
3) In preparation for this both Truls and Natalyia should try the  
analysis without the CC requirement but cutting on the the track vertex.
4)  Put all FV, Truls and Natalia's spectra on the same plot.

Upcoming presentations:
4/5 Steve: v2 analysis  He is doubtful he can make this.
4/12 Nathalia -   She will try, could we have a comparison of 3  
different pp analysis? This should be done for identified particles.
4/17 Ionut
4/23 Ramiro d.Au Hongyan dAu



Truls:

Status of hadron analysis is same as shown before.
There is a 25% difference for pp between (FV and Truls)
PID is added to the same set of runs/settings as for the hadron analysis
All corrections are used and PID acc maps used
PID will be done with TOF inv beta cuts and with RICH radius
Statistics are low at hi pT. Flemming thinks this is a nice approch. For
protons the distribution of protons is wider than for antiprotons.
FW: Below 0.45GeV energy loss is important.

To be done:
Find propper uncertainty in the inv beta and RICH radius
Check PID performance run by run
Compare results with other peoples analysis/publications

For FS he is focussing on 3 degrees because he wants high Pt to get  
PID and nuclear modification factors.

He is making a cut in the MRS at -0.1< y< 0.1
ACtion Item: he should check if he is using dead slats.

He has made a rough start at R_AA. But don't take them too seriously.
Normalization of pp. Multiply spectra by 0.82 to correct for missing  
cross section. This is not correct at high rapidity. He hopes to get  
back to this in a few weeks.
Action Item: Flemming is writing a note on this. A pt=1.5GeV particle
at y=3 takes half the momentum and causes a rapidity gap. This leaves no
particles in the CC counters.


pp analysis @ 62.4 GeV n. katrynska
They require a CC vertex for both RICH and TOF, as does Truls.
Both should redo the analysis without any requirement on CC.
We can use the track vertex for this. Ramiro use +- 40cm with track  
vertex.


Action: They should try the analysis without the CC requirement for  
RICH.                                                                    
                    1. Acceptance maps for identified particles.
2. Spectra for pions and protons received from FS.
fiducial magnet cuts: 0.5 cm;
vertex cuts: |z| < 25 cm;
RICH cuts: |x| < 24 cm; |y| < 16 cm;
applied corrections:
efficiency, geant corrections, acceptance;

PID looks good and acceptance maps seem to be OK.
She has some concern about anti-protons at high Pt.
This may be due to kaon contamination at high momentum.

Their dN/dy for protons is much bigger than HiJING at both y=2 and y=3.
Again we need to wait for Flemming's note.
Action: Put all FV, Truls and Natalia's spectra on the same plot.

AOB:
Selemon asked Truls about tracking efficiency in the MRS. Truls plans  
to use 90% for AuAu at 200GeV. (This comes from embedding tracks in a  
Monte Carlo code). At 62GeV efficiencies may be slightly higher since  
multiplicity is low. When he calculates the efficiency of each  
detector he gets a significantly lower number 80 something %. He  
suspects this is because there are too many reference tracks.  
Flemming has seen similar problems.

JH: What is the difference between Truls and Natalia:
Truls uses BANAPP2, track by track correction.
He is not quite sure that the errors are correct since he puts a  
weighted
number

Krakow is taking stuff from Peter Christinesen, modified by Radek.
They make Y,Pt maps and correct for acceptance. Flemming thought it was
more or less consistent with the "spectral object", ie data maps.  
However
software is written separately. Also PID is done by Mass^2 versus  
momentum rather the ring vs momentum. JH thinks PID should not be  
very different
since the RICH works so well.

Truls has some comments on Natialia's analysis.
For RICH cuts x<24, y<16. Truls says RICH inefficeint near center.
Natalia will change cut |x|<20 and |y|<15. Also she should not use  
fiducial cuts if she is using Chi^2 method in tracking.

Pawel: What about the offsets of the various detectors, eg T5? Truls  
they should be OK in database. JH try repeating analysis with very  
wide fiducial cuts. They will do this.






Michael Murray 30 March 2007
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