Dear BRAHMS Friends
You will all remember that at the last collaboration meeting we agreed
that each group should send out a short summary of what they are doing (
in relation to BRAHMS) every 2 weeks.
Here is the NBI report with input from some of the members.
Hope all other groups will follow.
1. Peter
> Peter is currently working on commiting the TPC calibration related code
> in brams_app and BRAT. It is in no way in as good shape as the Tof and BB
> code. The most notable change in the BRAT code will be that
> BrTPCHitCluster will inherit from BrDetectorHit.
> The goal is to include the energy correction and time row correction in
> the tracking software and make software public that can be used by other
> people to do the same analysis without changing BRAT code.
> (Target date : Tuesday 19 December)
>
> Then I will look on a request for optimal tracking/clustering parameters.
> The current idea is to do the tracking with a wide search window and then
> examine how the best found tracks behave one by one in the code.
> (Target date : Somewhere before new year)
> (Next step is resolution/efficiency.)
>
JJG comment: Optimal tracking/clustering parameters should really be
available next week so
that systematic analysis can start around new year.
2. Djamel.
Has been working on the calibration procedure for TOF and PID. A program
that uses the database is now available. It has been committed to BRAT.
This will be used in the upcoming systematic analysis of FS data (mainly
4 deg) starting next week . Software should be general and accurate
enough to be used by others and easy to use also for MRS.
Is also getting ready (with Claus) to produce larger sets of reduced
data that can be transferred across the Atlantic before Christmas for
systematic analysis with calibration code.
3. IGB
Is improving the PID code for FS. Looking at drift velocities, better
vertex determination,
possibility to apply Cerenkov cuts (also with Claus), centrality
selection, preparing list of useful runs for FS analysis (with Pawel).
4. Erik
> Background. I've taken a look at the background radiation from GBRAHMS
> simulations. It has been done by switching off different parts of the
> detector, in order to se what the different contributions were. I found
> out that the background correction should be about 11% which quite differ
> from Hito's 30% to 35%. I've talked to him and found out that it seems
> that the main contribution to the background is the tile it
> self. Therefore I'm currently doing a simulation to see how much the tile
> contributes to the background.
JJG comment: We have been playing with estimating the background
correction
at midrapidity in the tiles using a different strategy in GeanT
(combination of disabling beam pipe and other background producing
material and disabling hadronic interactions
in tiles). Fisrt shot today is that correction factor is approx. 40% at
eta=0.
(Very-very-very preliminary)
> Multiplicity. A script that describes the horseback for trigger 6 events
> has been made. Also a cut on vertex has been applied. Now I just need a
> cut on the centrality. The horseback graph should be compared with trigger
> 4 eve
5. Claus
This is what I'm looking at:
Pseudo Rapidity Density measure by T1}
Two small runs (2537 and 2538) where taken with D1 turned
off. The idea is to evaluate $dN/d\eta$ from the number of
tracks in T1 (like Rami did for TPC1, see analysis note 18).
From the data I've reconstructed around 35000 tracks of
which $\sim$ 8000 originates from the vertex. It's required
that a tracks points back to the vertex and that it lies
within the magnet gap.
The acceptance effect due to the moving vertex is not
trivial to evaluate, but I think there's enough
stastitics to make a narrow vertex cut around $z$=0.
This will give an acceptance of $\Delta\phi \approx 10^{\circ}$
and $2.9 \lesssim \eta \lesssim 3.2$.
The following week I hope to include the proper corrections
and centrality cut, and hopefully I'll find a number that's
consistent with the number from the BB analysis.
nts (=min bias). Also the demand of one track in forward arm shouold
be applied.
6. Hans
Will study geometric acceptance corrections for FS and MRS for use in T1
multiplicity
analysis and rough estimates of normalisation of hadron data.
7. JJG
Is getting from Wolfgang Cassing output of his model calculations. Plan
to use this for comparing with data at QM.
Have discussed EM+nuclear with Psenishnov. Discussing with Michael how
we can maske the most out of the contact with the theorist.
merry Christmas
JJ
--
____________________________________________________
JENS JORGEN GAARDHOJE
Assoc. Prof. of Physics, Dr. Scient.
Niels Bohr Institute,
University of Copenhagen
Blegdamsvej 17, 2100 Copenhagen
Denmark.
Tlf: (+45) 35 32 53 09 (dir)
(+45) 35 32 52 09 (secr)
Fax: (+45) 35 32 50 16
Email: gardhoje @ nbi.dk
Home page: http://alf.nbi.dk/~gardhoje
-Chair Ph. D. School of Physics at NBI.F.AFG.
(secr. Frank Kristensen 35 32 04 41, Ørsted Lab.)
-Member Danish National Commission for UNESCO
(secr. Ulla Holm 35 32 52 72, NBI)
___________________________________________________
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