Sessions - DPG-Tagungen

Nuclear Physics Tuesday
larger than that of the best existing source at the high-flux reactor of
Institut Laue Langevin, Grenoble. Test measurements at the TRIGA-
Mainz reactor, in collaboration with the University of Mainz, are planned
for January 2004.
Supported by the Maier-Leibnitz Laboratory (MLL) of LMU and TUM
at Garching and by the Deutsche Forschungsgemeinschaft.
HK 12.17 Tue 13:30 Foyer
IH-RFQ for the MAFF project at FRM-II — •Matteo Pasini 1 ,
Oliver Kester 1 , Michael Schumann 1 , Dieter Habs 1 , Thomas
Sieber 1 , and Alwin Schempp 2 — 1 Sektion Physik, LMU, München,
Germany — 2 Institute für Angewandte Physik, Universität Frankfurt,
Frankfurt, Germany
For the LINAC of the Munich accelerator for fission fragments (MAFF)
an IH-RFQ resonator is under construction. This resonator will operate
at a resonance frequency of 101.28 MHz, which is the upper frequency
limit for those structures and with a maximum duty cycle of 10%. The
MAFF IH-RFQ will accelerate ions with A/q < 6.5 from 3 keV/u injection
energy to about 300 keV/u. Intensive simulations with MWS and
PARMTEQ have been performed to reach a final design for the resonator.
A short model has been built and low level r.f. measurements are in
progress to test the calculations. The mechanical design has been confirmed
and the full power cavity will soon be ordered. The injection
scheme for MAFF has been modified to allow the installation of a low
frequency multi-harmonics buncher allowing thus more time separation
between main bunches. A new layout of the accelerator facility will be
presented.
HK 12.18 Tue 13:30 Foyer
Magnetic field stabilization by a Helmholtz-like coil configuration
— •Henneck R., S. Czekaj, M. Daum, P. Fierlinger, Z.
Hochman, M. Kasprzak, K. Kohlik, K. Kirch, M. Kuzniak, G.
Kuehne, D. George, A. Pichlmaier, A. Siodmok, A. Szelc, and
L. Tanner — PSI
For highly sensitive measurements of the neutron electric dipole moment
(EDM) the magnetic field has to be stable on a level below picoTesla.
One of several measures we employ to achieve this (apart from
passive mu-metal shielding with shaking, resonance frequency stabilization,
internal field stabilization, multi-chamber system) is to use an external
field coil system which can stabilize the ambient external field at
a predefined value. Here we report on the construction and characterization
of such a system in the magnetic test facility at PSI. The system
actively stabilizes the field along the axis of the EDM experiment by
means of 4 coils in a Helmholtz-like configuration. Additional coils serve
to compensate for transverse ambient field components. Due to the 4coil
geometry large magnetic suppression factors are expected. Because
of the long integration times in the EDM experiment (about 100 s or
more) only slow disturbances have to be corrected for. The performance
of the system has been measured using static as well as moving magnetic
sources and suppression factors in excess of 200 have been observed.
HK 12.19 Tue 13:30 Foyer
Proton detection in aSPECT — •Gerd Petzoldt 1 , Stefan
Baeßler 2 , Jim Byrne 3 , Ferenc Glück 2 , Joachim Hartmann 1 ,
Werner Heil 2 , Raquel Muñoz Horta 2 , Igor Konorov 1 , Marius
Orlowski 2 , Yuri Sobolev 2 , Maurits van der Grinten 3 , and
Oliver Zimmer 1 — 1 Physik Department E18, Technische Universität
München — 2 Institut für Physik, Universität Mainz — 3 University of
Sussex, Falmer, Brighton, UK
Present neutron decay data indicates that unitarity tests of the
Cabbibo-Kobayashi-Maskara matrix fail by about 3σ. With the retardation
spectrometer aSPECT, we will measure the electron-antineutrino
correlation coefficient in neutron decay a by determinig the shape of the
proton recoil spectrum, which is sensitive to a. We hope to increase
the precision of the measurement by at least one order of magnitude,
compared to older experiments. Determinig the upper left element Vud
from a will allow an independent test of CKM unitarity.
The measurement requires a very sensitive detection system. We will
use segmented Si-PIN diodes, which allows us to supress correlated electron
background by applying an E×B drift in front of the detector. The
structure also reduces capacitive noise of the detector. For the readout
of the detector, a fast, low-noise electronics has been developped.
The detection system and calculations on the systematic effects on a
to be expected from the detector properties, will be presented in this
poster.
This work is supported by the MLL Garching and the BMBF.
HK 12.20 Tue 13:30 Foyer
Design of the new Crystal-Barrel forward cone — •Philipp
Hoffmeister and Christoph Wendel for the CBELSA collaboration
— Helmholtz-Institut für Strahlen- und Kernphysik der RFWU Bonn,
53115 Bonn
The main purpose of the Crystal-Barrel detector at ELSA is to investigate
the structure of hadrons. A barrel-shaped setup of CsI-Crystals is
used, allowing the investigation of multi-photon final states. Since the
Crystal-Barrel is a ”fixed target” experiment, the forward direction demands
special attention. Until the end of 2003, the TAPS detector was
used to cover the inner 30 ◦ of the forward direction. The loss of the TAPS
detector made it necessary to construct a new forward calorimeter with
fast trigger capabilities for photons and charged particles. Therefore the
pre-TAPS Crystal-Barrel setup is modified by replacing the photodiode
readout with fast photomultipliers and a redesigned electronic backend,
providing a trigger fast enough to cope with the high photon flux used
in the experiment. Additionally two thin layers of szintillating material
with fibre readout are placed in front of the crystals, providing a fast
trigger for charged particles.
This poster will describe in detail these modifications and the design of
the new Forward Plug.
HK 12.21 Tue 13:30 Foyer
The Frankfurt Funneling Experiment — •Jan Thibus, Ulrich
Bartz, Norbert Müller, Alwin Schempp, and Holger Zimmermann
— Institut für Angewandte Physik, Johann Wolfgang Goethe-
Universität, Robert-Mayer-Str. 2-4, D-60054 Frankfurt am Main, Germany
Funneling is a procedure to multiply beam currents at low energies
which is required for the proposed new high current accelerator facilities
like HIDIF or ESS. Funneling can be done using several stages in which
multiple beams are merged to a common beam axis. Thus very high
energies and beam currents can be achieved. The main goal is to keep
the emittance nearly unchanged. The Frankfurt Funneling Experiment
consists of two ion sources, a Two-Beam RFQ accelerator, two different
funneling deflectors and a beam diagnostic equipment system. The
whole set-up is scaled in He + instead of Bi + of the first funneling stage
of a HIIF driver. The progress of our experiment and the results of the
simulations will be presented.
HK 12.22 Tue 13:30 Foyer
CONCEPTUAL DESIGN OF A 350 MHZ- PROTON- RFQ
FOR GSI — •Benjamin Hofmann, Lutz Brendel, Kai-Uwe
Kuehnel, and Alwin Schempp — IAP Frankfurt
Part of the future project of GSI is a p- linac for the production of
anti-protons. The first component of this linac is a 4- Rod-RFQ operating
at 350 MHz. Design studies have been made using the Parmteq- and
Microwave Studio code to optimize the field distribution and symmetry.
A short copper model has been built for field measurements. Results of
the design studies will will be presented.
HK 12.23 Tue 13:30 Foyer
Measurements on a focusing drift tube cavity — •Kai-Uwe
Kuehnel 1 , Carsten Peter Welsch 2 , and Alwin Schempp 1 —
1 IAP Frankfurt — 2 MPI-K Heidelberg
The efficiency of RFQs decreases at higher particle energies. The DTL
structures used in this energy regions have a defocusing influence on
the beam. To achieve a focusing effect, fingers with quadrupole symmetry
were added to the drift tubes. Driven by the same power supply
as the drift tubes, the fingers do not need an additional power source or
feedthrough. The beam dynamics have been calculated with PARMTEQ
and the rf properties have been examined using Microwave Studio. A
compact spiral loaded cavity with four accelerating gaps has been built
for light ions with an energy of 2 MeV/u. The overall length of the cavity
is 0.36 m with a cell length of 61 mm. The design frequency is 160 MHz.
The results of the low level measurements as well as bead pertubation
measurements are shown.
HK 12.24 Tue 13:30 Foyer
LORD of the Rings — •Carsten Welsch 1 , Joachim Ullrich 1 ,
Kai-Uwe Kühnel 2 , Christian Gläßner 2 , Alwin Schempp 2 , and
Horst Schmidt-Böcking 3 — 1 Max-Planck-Institut fuer Kernphysik,
Heidelberg — 2 Institut fuer Angewandte Physik, Frankfurt — 3 Institut
fuer Kernphysik, Frankfurt