[Brahms-l] BRAHMS Minutes 13 April 07

         Minutes of Brahms Analysis meeting, Friday 13th of April 2007
         =============================================================
                                                      Submitted by  
Michael Murray

Present: JH, Flemming, Ionut, Catlyn, Hongyan Michael, Dipali,  
Selemon and others.

	
Agenda: http://indico.cern.ch/conferenceDisplay.py?confId=14855

Friday 13 April 2007	top
09:30 	Status of auau 61 GeV K, pi analysis Ionut Arsene
10:00 	DIS 2006 presentation JH Lee
10.40   PP at 62GeV  Alte

Action Items:
Ionut: In MRS make bigger bins. Check STAR or PHENIX paper on mid- 
rapidity 62GeV. He has done other centrality bins and will present  
more next week.
Catlyn Correct for dead bands in X for T2.

Data used DST production version 4
MRS settings: 90(A/B)1050, 90(A/B)350, 45 (A/B)1050, 40A1050
FS settings: 6 degree (A/B)861, 4(A/B)608, 3(A/B)1723

He uses Banapp Method 1 trg3 events for MRS, trg2 events for FS.
minimum bias trigger is trig 1(BB) for 0 30% centrality
events and trig 4(ZDC) for 30 60% events. I am not using
any correction for minimum bias trigger inefficiency.
vertex selection: BBC vertex must be within [ 30,+30] cm
He is not sure about min bias inefficiency but Flemming thinks its OK.

He does fiducial cuts on TPM2 and RICH, TOFW & H2
The track must be within a 5 sigma elliptic region around the vertex  
for both MRS and FRS have a good Chi^2 and be within acceptance map.  
Then he corrects for efficiency of tracking, multiple hits and PID (3  
sigma) and also for weak decays. He corrects for contamination of  
kaons and protons when RICH is in veto. For kaons this amounts to  
20-30% correction.

MRS pion spectra have some mismatch at different settings. For the  
forward region he worries about the kaons identified by "indirect"  
PID, ie RICH veto and TOFW => .NOT. protons.

Action Item: In MRS make bigger bins. Check STAR or PHENIX paper on  
mid-rapidity 62GeV. He has done other centrality bins and will  
present more next week.

JH Review of his DIS 2007 talk:
===============================
Spin results same as preliminary data shown at last spin meeting but  
now we have 63GeV cross sections and some Pt depedence.

Factorization theorem with short-distance NLO pQCD describe
RHIC partonic dynamics
Transverse Single Spin Asymmetries(SSA): probing partons'
transverse motion and multi-parton correlations inside a hadron
At large xF , transversity and multi-parton correlation is more
exposed
Present energy (62.4, 200 GeV) and Flavor dependent (pi;K)
SSAs and cross-sections at large-xF

NLO pQCD not working too well at ISR, 200GeV is the first energy  
where the NLO pQCD works well.
The  62GeV cross section are in reasonable aggreement between data  
and calculations. He may skip showing proton data since this could  
sidetrack his talk.


He compares asymetries to 2 models, (Collins no longer describes low  
energy data well) whereas Sivers is still in the running but  
underpredicts our data. Twist 3 seems to be closer but they have some  
input from data. It is a puzzle that asymetries are similar for kaons  
and pions.


Large xF dependent SSAs seen for pions and kaons, suggesting
Sivers mechanism plays an important role.
Described (qualitatively) by Twist-3
Main contributions are from leading (favored) quarks, Sivers or Twist 3.
Power-suppression of assymetries by ~ 1/pT seems to be seen at 200GeV.

www4.rcf.bnl.gov/~videbaek/analysis

Flemming.
http://www4.rcf.bnl.gov/~videbaek/analysis/FS_Kaons.png
shows that we can get out to Pt = 1.5 GeV for kaons. It might be  
possible for theorists to produce cross sections down to this Pt.

Catlyn. PP at 62GeV
===================

Cuts
X=±20 cm Y=±15 cm at back of RICH
• X= 26, +28cm, Y= 8,+5cm at back of TPM2
• Vertex z range: ±30 cm for all settings
• Vertex back projection cut:  3.5 sigma
• Accmaps:
• Delta pt = 0.025
• Delta y = 0.01
• Error: 5%

Uses conservative PID limits at 2 & 3 degrees.
Direct pions: 5 10 GeV/c
Direct kaons: 10 20 GeV/c
Direct protons: 20 30 GeV/c
Indirect protons: 10 15 GeV/c
(Protons between 15 20 GeV/c currently not identified.)
There is a significant contamination of antiprotons that he handles  
by subtraction of background.


For MRS he uses TOFW for PID, since TOFW2 has smaller acceptance and  
statistics.
He has k/pi separation to about 2.2 GeV/c and P/pi separation to  
about 3 GeV/c
Tracks with momenta below 400 MeV/c are not used
He corrects for track and  RICH inefficies. .

For corrections he uses
Bramreco GEANT files
Tracking efficiency (nkv_2)
RICH inefficiency (0.97)
PID algorithm efficiency
RICH contamination (3 % of pions and kaons).
CC correction in FS (0.82), Flemming has not looked at this recently.  
This
factor is OK for the MRS but not for the FS
No H2 efficiency, Flemming (should be 98%, correct for dead slats).
He has some dead bands in X for T2.

Action Item: Correct for these:

_______________________________________________
Brahms-l mailing list
Brahms-l_at_lists.bnl.gov
http://lists.bnl.gov/mailman/listinfo/brahms-l