Monday, March 11, 2002 - DPG-Tagungen

Nuclear Physics Thursday
(LHC), where rapidity densities of charged particles up to dN/dy = 8000
are anticipated in collisions of Pb nuclei at √ s =5.5 ATeV.
Along with a general overview of the detector, results from extensive
in-beam tests with regard to transition radiation yield, pion rejection,
and tracking performance will be presented. Using the experimental data
the performance of the fast electron trigger has been simulated. Finally,
the anticipated performance of the trigger for quarkonia measurements
at central rapidity will be demonstrated.
HK 41.3 Thu 14:45 E
Investigation of the event anisotropy with the CERES/NA45
experiment — •Jana Slivova and Jovan Milosevic for the
CERES/NA45 collaboration — Physikalisches Institut der Universität
Heidelberg, Philosophenweg 12, 69120 Heidelberg
Using the data obtained at the CERES/NA45 experiment the elliptic
event anisotropy was studied in Pb+Au collisions at 40, 80, and 158
AGeV/c. This anisotropy is quantified by the second Fourier coefficient
(v2). Results are obtained both for identified pions and for charged particles.
We will compare values of v2 obtained using different methods
- standard flow analysis with respect to the reaction plane, two-particle
correlations, and preliminary results from the recently introduced method
of cumulants (Phys. Rev. C 63, 054906 (2001)).
HK 41.4 Thu 15:00 E
Charge fluctuations in nuclear collisions: experimental results
and model studies. — •Jacek Zaranek 1 , P. Dinkelaker 1 , L.
Betev 1 , C. Blume 2 , R. Bramm 1 , P. Buncic 1 , M. Ga´zdzicki 1 ,
T. Kollegger 1 , I. Kraus 2 , A. Mischke 2 , R. Renfordt 1 , A.
Sendoval 2 , R. Stock 1 , H. Ströbele 1 , D. Vranic 2 ,andA. Wetzler
1 for the NA49 collaboration — 1 University of Frankfurt, IKF —
2 GSI, Darmstadt
HK42 Instrumentation and Applications V
Study of event-by-event fluctuations of electric charge in high energy
nucleus-nucleus collisions may provide information on the state of matter
in an early stage of the collision. They should be also sensitive to the
number of resonances at chamical freez-out. Preliminary experimental
data obtaind by NA49 on charge fluctuations in central Pb+Pb collisions
at 40, 80 and 158 AGeV will be shown. The results will be discussed in
the framework of serveral models in which the effects of global charge
conservation, resonances decay kinematics and QGP formation are studied.
HK 41.5 Thu 15:15 E
Event-by-Event Fluctuations at 40, 80 and 158 AGeV/c in
Pb+Au Collisions from CERES/NA45 — •Hiroyuki Sako and
Harald Appelshäuser —GSI,Darmstadt
Event-by-event fluctuations have been proposed as probes to search
for the QCD critical point and deconfined phase.
We present fluctuations of mean pT and charge multiplicity ratios at
40, 80, and 158 AGeV/c in Pb+Au Collisions. We also compare them
with other experimental data and with theoretical expectations.
Time: Thursday 14:00–15:30 Room: F
Group Report HK 42.1 Thu 14:00 F
The AGOR facility — •S. Brandenburg, W. van Asselt, J.P.M.
Beijers, H.R. Kremers, T. Nijboer, H. Post, and S . van
der Veen — Kernfysisch Versneller Instituut, 9747 AA Groningen, the
Netherlands
The heart of the AGOR facility at the KVI is a superconducting cyclotron,
constructed by a collaboration of the KVI and the IPN, Orsay,
France. The facility is operational since 1997 for some 4500 hours per
year. The cyclotron can accelerate both light and heavy ions (e.g. protons
up to 190 MeV, lead down to 6 MeV/nucleon). It is equipped with
ion sources for polarized hydrogen, light and heavy ions.
The basic characteristics and performance of the facility will be described.
The design issues related to the wide range of ions and energies
will be discussed. Furthermore attention will be given to new developments,
such as the acceleration of low-intensity triton beams.
HK 42.2 Thu 14:30 F
New Developments in Cryo Targets for the External COSY Experiments
— •S. Abdel-Samad, M. Abdel-Bary, andK. Kilian
for the COSY-TOF collaboration — Forschungszentrum Juelich
For pp and pd interaction studies at COSY a very light cryo target
has been developed. The target thickness in beam direction defines the
interaction probability and thus the statistical precision. However all
material which can be hit by particles from the reaction under study
will produce secondary scattering and unwanted background. Therefore
already the target thickness has to be kept short. Much more important
is to keep the transversal size of the target very small and the heat conductors,
mounting elements and thermal isolation as light as possible.
The Juelich cryo targets have been optimized over some years in this
aspect. A drastic reduction of the total mass of the target arrangement
was achieved by using very thin walled, small diameter heat pipes, by
using aluminum for condensers, by target cells of galvanically deposited
copper and by 0.9 µm Mylar windows. Up to 2 meter long heat pipes
are operational. For bubble free operation a temperature stability with
< 0.2 K fluctuation has to be achieved. Details of the targets will be
shown.
HK 42.3 Thu 14:45 F
A Silicon Tracking Telescope for Spectator Proton Detection
— •A. Mussgiller 1 , G. Fiori 1 , T. Krings 1 , S. Merzliakov 2 ,
D. Protic 1 , and R. Schleichert 1 for the ANKE collaboration —
1 Institut für Kernphysik, Forschungszentrum Jülich — 2 Laboratory of
Nuclear Problems, JINR, Dubna, Russia
The identification and tracking of low energy protons enables the use of
deuterons as an effective neutron target. For this purpose a self-triggering
tracking telescope has been developed. The telescope consists of three
layers of double-sided silicon strip detectors mounted inside the COSY
vacuum. The setup allows the identification of protons from 1.5 MeVto
40 MeV via the ∆E/E method and particle tracking over a wide range
from 1.5 MeV protons to minimum ionizing particles. Results of the first
measurements will be presented.
HK 42.4 Thu 15:00 F
Nuclear Polarization of Molecular Hydrogen — •F. Rathmann 1 ,
J.T. Balewski 2 , J. Doskow 2 , W. Haeberli 3 , B. Lorentz 1 , H.O.
Meyer 2 , P.V. Pancella 4 , R.E. Pollock 2 , B. v. Przewoski 2 ,
P.A. Quin 3 , T. Rinckel 2 , Swapan K. Saha 5 , B. Schwartz 3 , T.G.
Walker 3 , A. Wellinghausen 2 ,andT. Wise 3 — 1 IKP, FZJ, Jülich,
Germany — 2 IUCF, Bloomington, USA — 3 Dep. of Physics, University
of Wisconsin-Madison, USA — 4 Western Michigan University, Kalamazoo,
USA — 5 Bose Institute, Calcutta, India
We have measured the nuclear polarization of hydrogen molecules
formed by recombination of polarized atomic hydrogen gas [1]. A polarized
atomic hydrogen beam is incident upon a copper recombination
zone and subsequently drifts into an internal target located in a straight
section of the IUCF Cooler ring. The target contains an internal valve
that allows us to rapidly alternate between a mostly atomic and a mostly
molecular target. A comparison of the target polarization for these two
states can be used to determine the fraction of the initial atom polarization
that survives recombination and subsequent wall collisions in the
target. That fraction was studied for temperatures between 50 K and
300 K and for applied magnetic fields between 0.5 mT and 0.6 T. The
target polarization was measured with a 200 MeV longitudinally polarized
proton beam using the known [2] large pp elastic spin correlation
coefficient Azz. The apparatus, measurement methods, results and inter-