From: Flemming Videbaek (videbaek@sgs1.hirg.bnl.gov)
Date: Sun Nov 03 2002 - 19:29:52 EST
Enclosed activity report from the collaboration members.I hope that the next report can
be submitted to the collaborations on or about Dec 1 just before the collaboration meeting.
The material is essentially reported as received.
regards
Flemming
PS Do I have any volunteer for taking over this job as we discussed in May?
Oslo/Bergen:
___________________________________________________________
Spectra and yields from Au-Au collisions - Jens Ivar:
Future plans:
* Estimation of Pi and K yields within acceptance, and also
estimation of the portion of fitted spectra that are extrapolated.
* Additional physics corrections simulations, including beam pipe
contributions etc.
* Do a thorough estimation of the systematic errors on the yields.
_______________________________________________________________
Yields as functions of rapidity, comparing various colliding
systems - Bjørn:
Currently working on:
* Making DSTs from p-p data in the bdst framework, using Kris'
global track files.
* Doing a simple yields analysis for Au-Au and p-p.
* Looking at d-Au simulations to prepare for the upcoming run.
The intention is to present some simulated rapidity distributions
at the collaboration meeting.
_______________________________________________________________
Pi0 measurements in BRAHMS - Zhong-Bao Yin:
* Performed simulations of Pi0 reconstruction efficiency in MRS
with a 2 mm lead converter in front of TPM1. For 50000 thrown Pi0's
in the momentum interval 4 - 6 GeV, two were reconstructed. Conclusion:
Not feasible to measure Pi0's in MRS with a converter.
Future plans:
* Work together with Claus on high-p_T charged hadron spectra.
_______________________________________________________________
Efficiency calculations - Truls:
* Truls has rewritten the TPC tracking efficiency code BEAT to a
bratmain compatible framework, using "package" classes BrEffGeantModule
and BrEffRecoModule to take care of the multiple inputs and track tables.
A few new problems emerged during the last weeks, but have now apparently
been solved. Very preliminary results look sensible.
Currently working on:
* Producing tracking efficiency results for MRS and FFS.
Future plans:
* Study the TPC two-track resolution, compare efficiency results
to Pawel's calculations, and finish his thesis.
___________________________________________________________
Lambda project - Elin, (Trine, Bjørn):
* A small but clear lambda signal is found in the MRS at 40 and 35
degrees, see for instance:
http://lynx.uio.no/trine/brahms/lambda/lambda_35_decpt2.ps.
(invariant mass spectra for Lambda and anti-Lambda at 35 deg.)
Statistics is marginal, but may allow extraction of anti-Lambda/Lambda
ratios and yields at the most forward MRS angles, although with
HUGE uncertainties.
* Simple additions for lambdas have been incorporated in Peter's
acceptance framework.
Currently working on:
* Lambda search at more angles, utilizing as much as possible of
the available data set.
* Extracting anti-Lambda/Lambda ratios at selected angles in the
MRS.
Future plans:
* Generate high-statistics acceptance maps and extract Lambda and
anti-Lambda yields for the MRS at selected angles.
___________________________________________________________
Spectra and yields from p-p run - Mads, (Bjørn):
Currently working on:
* Writing software for efficiency extraction of spectra and yields
from existing dst's and acceptance maps, for MRS and FS. Currently
gaining experience by looking at Au-Au data.
Future plans:
* Extract K and pi yields in p-p collisions
_______________________________________________________________
Svein Lindal (new student in Oslo):
Future plans:
* Get acquainted with the BRAHMS software and experimental setup
________________________________________________________________
Bucharest
I would like to send you some information on our recent activities:
- Ion Sorin ZGURA is now at CERN; he works for GRID and ROOT;
- Catalin RISTEA, Ionut ARSENE, Sorin ZGURA, Alexandru JIPA and Calin
BESLIU worked on the study of the influence of the vertex cuts on the charged
particle rapidity; it seems that a limitation in the vertex range could affect
the multiplicity distribution;
- Alexandru JIPA, Oana RISTEA, Catalin RISTEA worked on some aspects
related to temperatures, hydrodynamic flow and frezee-out; I believe that it is possible to improve the information contained here and to try to send this work for publication.
- Alexandru JIPA, Mihai Potlog, Calin BESLIU, Sorin ZGURA, Catalin RISTEA
worked on the presence of the resonance matter in Au-Au collisions at 130
A GeV and 200 A GeV.
Texas A&M
TAMU BRAHMS progress report 28-Oct-2002
K. Hagel
I have extracted preliminary ratios from the p+p data. Some of the
details leading up to the generation of these ratios was discussed in
the last progress report of 9-Sep-2002. These ratio results were shown
at the DNP meeting at MSU.
There are two new plots of interest since the last progress report. The
first is the root-s dependence of the pion and proton ratios at y=0.
The lower energy ISR data was obtained from A. Rossi et al. Nucl. Phys.
B 84 (1975) 269. This dependence is shown at
http://Cyclotron.tamu.edu/hagel/brahms/ProgressReport-28-Oct-2002/ratiosVsS.gif
where our data is represented by the solid points and the ISR data is
represented by the open points. In this plot we see a fairly smooth
dependence of the pion points. The proton points would indicate a
steeper rise at lower energies with a flattening out as we get to RHIC
energies.
The second plot of interest is the rapidity dependence of the ratios.
This is shown in
http://Cyclotron.tamu.edu/hagel/brahms/ProgressReport-28-Oct-2002/ratiosVsY.gif
. The error bars indicate a 10% systematic error on the points. For
reference, the auau points are shown on the same type of plot at
http://Cyclotron.tamu.edu/hagel/brahms/ProgressReport-28-Oct-2002/auauratiosVsY.gif
.
When overlaying these plots, one observes that the pbar/p ratios follow
the same trends in p+p as they do in Au + Au. The p+p pion ratios
decrease at higher y and the kaon ratios are in general lower.
Finally, since we enjoy plotting the ratios vs each other, we show in
http://Cyclotron.tamu.edu/hagel/brahms/ProgressReport-28-Oct-2002/pbarpVsKplusK.gif
the K-/K+ ratios plotted vs the pbar/p ratios. The mid rapidity points
are the ones with the highest ratios and the rapidity scale increases as
the pbar/p and K-/K+ ratios slide downwards towards the left. Of
course, the line represents the **1/3 dependence. We see that at y=0
that we the correlations of the ratios lie on the **1/3 dependence line
whereas they deviate from the line with increasing rapidity in contrast
to the Au+Au data.
In the next weeks starting as soon as HPSS becomes operational again, I
plan to work towards building statistics by using all of the data there
is. In addition, by changing some settings in the Inel analysis code,
Flemming was able to resurrect for me a number of runs which includes
the 8 degree FS run. Having that point will help to make sure things in
the FS are consistent (or force me to look for more possible problems if
it is not). In addition, I have been in communication with Pawel
regarding BFS tracking efficiencies as well as matching. I have gone
back and looked at matching parameters from the prel reco stuff and they
look very constant and close to the settings used in generating the
matched tracks. So although that was not controlled very carefully, the
results should not change dramatically due to that.
BNL
The BFS electronics has been re-allocated. The HV main-frame in place on the new sliding plate. The DC was re-cabled and re-installed by T.Kosiz and P.Stazsel, and are ready to be surveyed. Some additional HV cables for the DC are being assembled. A few recent pictures from the BFS area will be posted on the Brahms detector page. The TD1 triggers counter has been re-installed; The design for the MRS start-time trigger is proceeding.
The second prototype for the trigger-board has been debugged. The Vxwork code for the slow controls Vme processor has been written, tested, and used to checkout the trigger board using a simple perl-script.
The production of the complement of 15 boards is underway. Preparation for installation of crates on the MRS platform is underway.
All windows for the TPCs are now Al foil. DVM measurements are in progress for a systematic study o
All TPC are at their previous locations on platform, ready for survey of time variations.
The group has much discussion on triggers for d-Au in order to get to both an efficient min bias trigger, and a reasonable online determinations. Several simulations have been carried out by JH, Hiro, Burt and fv. Some of conclusions and results are included in the trigger summary http://www.sdcc.bnl.gov/brahms/private/detectors/pp/index.html
Which were also announced a short while ago.
After the reconstruction of the early MRS data runs has been completed, EJK is looking at peripheral events for 200 GeV/c. Since no specific triggers the statistics requires that as many runs as possible is used. The 130 GeV data are also being revisited.
In the course of this study it was found that systematic differences between mass-squared spectra exists when comparing central and peripheral collisions. This can be interpreted as a small timing change in the beam - beam t0 (in the range of 50-100 psec.).
U.Kansas
The C4 box is now complete. We still need to check the latest pieces
for leaks (primarily
the back box that contains the large 45 degree mirrors), but otherwise
the assembly is
ready. The final drawing for C4 can be found at
http://www.phsx.ukans.edu/~sanders/Cherenkov .
We have been looking at the particle multiplicities for the pp run of
last year. Hiro has been successful in extracting values of dN/deta for
the tile array using the energy loss analysis employed for the Au+Au
data. These results have been presented as "Preliminary" at the PANIC
meeting and at the Fall DNP meeting. An attempt has also been made to
extract dN/dEta
information from the Si array using the statistics of single hits in
these detectors. This latter analysis has not been successful and it
appears that there may be a low-energy (presumably delta ray) background
that is not found in the GEANT simulations.
The Si array analysis further highlights the importance of setting up a
new trigger for next years run that would give us
some information on non-collision, beam-related background in the Mult
array.
NBI
Activity report from NBI-HEHI, week 44, 2002.
The primary activity here has been to put the finishing (!?) touches
on the 200 Gev ratios paper, and to get the two remaining QM
contributions (from IGB and DO) finished.
In addition to this we are working on the following projects.
1. Claus is working on improving the understanding of C1, and--it is
hoped--the performance of the C1 PID software. One thing that is
puzzling us at present is that if one plots the number of expected
photons versus the number of observed photons, the behavior of the
curve changes as a function of FS angle. We do not know if the
correlation is really with angle (it could also be time?) and Claus is
continuing to work on this. A BRAN should follow before the next
collaboration meeting.
2. Claus is hosting Zhongbao Yin (from Bergen) and Mads Mikkelsen
(Oslo) to teach them how to analyze BRAHMS data. They will be here
during week 45. Concretely, we expect that in this week it should be
possible to redo the 12 degree High pt analysis (due to bugs corrected
since QM, we expect to find more tracks in the full FS). ZY will then
start to look at MRS high pt (as I understand) and MM will start
looking at p+p data.
3. Peter and Djamel are revisiting the FS analysis. In particular,
they would like to check the matching of different settings (angle and
field). Once this is well understood, we can begin to get more points
for yields vs. rapidity.
4. David Sandberg has been using the so-called 'blast-wave' model
to simultaneously fit pbar,p, K+,K-,pi+, and pi+ spectra.
Summary plots can be found here:
http://www.nbi.dk/~sandberg/blast/expfit.ps
and
http://www.nbi.dk/~sandberg/blast/totalflow.ps.
These fits at y=0 yield T~120, beta~0.6. If I recall correctly, this
is consistent with y=0 results shown by both STAR and PHENIX. Whether
or not it is good to be consistent with STAR and PHENIX I'll leave
open for debate.
5. IGB (and a new student who IGB hopes will do most of the work!) has started to look a little into d+Au, using Hijing. I
suppose others are/have looked at this. I'd like very much to know
what has happened. For example, can we use crs to do full BRAG
simulations of Hijing? Or is someone working on this already?
6. Christian is putting the finishing touches on his Master's thesis.
7. As mentioned above we are finishing the QM contributions. There
are a few remaining details to sort out. In particular, we need to
have a consistent set of yields in all our QM contributions. Djamel
and IGB are communicating with JHLee to resolve this ASAP.
------------------------------------------------------
Flemming Videbaek
Physics Department
Brookhaven National Laboratory
tlf: 631-344-4106
fax 631-344-1334
e-mail: videbaek@bnl.gov
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