Transcript High Precision Mass Measurements with the Penning Trap

Future Penning Trap Experiments at GSI / FAIR –
The HITRAP and MATS Projects
K. Blaum1,2 and F. Herfurth1 for the HITRAP and MATS Collaboration
1GSI
Darmstadt, 2Johannes Gutenberg-University Mainz
Introduction
Motivation and Fields of Application
The mass and its inherent connection with
Ion traps play an important role not only in high-precision experiments on stable
the nuclear and atomic binding energies is
particles but also on exotic nuclei. Besides accurate mass measurements they
have recently been introduced to nuclear decay studies and laser spectroscopy as
well as to tailoring the properties of radioactive ion beams. This broad usage of
Atomic
Physics
trapping devices at accelerator facilities is based on the manifold advantages of a
e- binding energy
QED test
three-dimensional ion confinement in well controlled fields: First, the extended
ions can be cooled and manipulated in various ways, even polarization and
Nuclear
Structure
nuclear binding energies,
Q-values
m/m  1·10-7
mass values are important for a variety of
applications, ranging from nuclear-structure
shell closure, pairing,
deformation, halos,
isomers
m/m  1·10-10
observation time is only limited by the half-life of the radionuclide of interest,
yielding very high precisions for instance for mass measurements. Second, stored
a basic property of a nuclide. Thus, precise
Nuclear
Physics
studies, test of nuclear mass formulas, to
tests of the weak interaction, QED, and of
m/m  1·10-7
trap assisted
decay
spectroscopý
the Standard Model. The required relative
accuracy ranges from 10-5 to below 10-10
trap assisted
laser
spectroscopý
exotic
systems
Weighing
for stable and short-lived nuclides, which
most often have half-lives well below 1 s.
charge breeding of the ions are possible, giving a unique tool in order to prepare
Weak
Interaction
otherwise impossible experiments. Third, it is possible to create a backing free
and
e+)
very efficiently,
symmetry tests,
CVC hypothesis
reducing a number of uncertainty in classical spectroscopic experiments. The
HITRAP and MATS Collaborations propose advanced trapping systems at GSI
AstroAstrophysics
and the future facility FAIR for high-precision mass measurements, tests of QED
spectrometry has made this method a
tests of nuclear models
and formulae
nuclear synthesis,
r- and rp-process m/m < 1·10-7
m/m < 3·10-8
Substantial progress in Penning trap mass
Fundamental
Properties
prime choice for precision measurements
on stable and rare isotopes. Furthermore,
m/m  1·10-7
ion traps can be used advantageously for
precision decay and laser spectroscopy.
using highly-charged heavy ions, and decay studies on short-lived radionuclides.
GSI and FAIR
Figure of the proposed Experimental MATS Setup
SIS 100/300
radionuclides:
ions and radioactive
measurements
nuclei. FAIR (Facility
electron and alpha spectroscopy. The
for Antiproton and Ion
experimental setup of MATS is a unique
is
the
future of GSI. The
future facility is going
UNILAC
FRS
HESR
ESR
Super
FRS
ESR
CR
RESR
NESR
different techniques to very short-lived
heavy, highly-charged
Research)
SIS 18
With MATS at FAIR we aim for applying two
to provide ion beams
High-precision
and
in-trap
mass
preparation, and a high precision Penning
trap system for mass measurements and
decay studies.
so
intensive
versatile tool itself and allows different high-
secondary beams -
precision experiments resulting in a broad
exotic
bare
uranium,
nuclei
or
antiprotons - can be
produced for the planned experiments. HITRAP will use the existing GSI facility
and the ESR storage ring to decelerate heavy, highly-charged ions. At FAIR
Preparation
Penning trap
for charge breeding, ion traps for beam
intensity and energy
e.g.
Roof crane (2 ton)
Measurement
Penning trap
combination of an electron beam ion trap
with currently unique
that
First Floor
conversion
4.4 m
of the art research on
Each subsystem
is a
Ground Floor
EBIT
4.3 m
GSI stands for state
physics output. For beam preparation an
ion beam cooler and buncher will be used.
HV Cage
A magnetic multi-passage spectrometer is
2.0
source of radioactive nuclei and to collect light particles
(e-
HV Cage
implemented for q/A separation of the
HITRAP will be the core of the low energy ion and antiproton facility FLAIR.
highly-charged ions. For further details see
MATS will be installed at the Low Energy Branch of the Super-FRS at FAIR,
the Technical Proposal submitted to the
where radioactive beams with up to 10 000 higher yields than anywhere else will
FAIR.
Side View
10.0 m
be available.
m/q
selec tion
Experiments at HITRAP and MATS
The HITRAP project
HV Cage
EBITUNILAC
Testion
source
1 GeV/u
Testion
source
4.5 m
MPS
SIS
Top View Ground Floor
HV Cage
Cooler
Penning Trap
6 keV/u
Linear
Decelerator
4 MeV/u
FRS
ESR
400 MeV/u
Experiments
stripper
2 keV/u
HITRAP will be installed at GSI in order to provide and study bare heavy nuclei or heavy nuclei
A number of experiments are planned at HITRAP and MATS using a high-precision Penning trap. Mass measurements
with only few electrons at very low energies or even at rest. Highly-charged ions will be
will be performed at both setups using the high accuracy potential and especially at MATS the high sensitivity. A
produced by stripping at relativistic energies. Another possibility is the production of radioactive
relative mass uncertainty of
10-9
for radioactive, short lived ions and
10-11
for stable, highly-charged ions can be
nuclei using the fragment separator FRS. After electron cooling and deceleration in the
reached by employing highly-charged ions and a non-destructive Fourier-Transform Ion-Cyclotron-Resonance (FT-
Experimental Storage Ring ESR the ions are ejected out of the storage ring at 4 MeV/u and
ICR) detection technique on single stored ions. The use of the FT-ICR technique provides true single ion sensitivity.
further decelerated in a combination of an IH and RFQ structure. Finally, they are injected into a
This is essential to access isotopes that are produced with minimum rates and that very often are the most interesting
Penning trap where the ions are cooled to 4 K. From here, the ions can be transferred in a quasi
ones.
dc or in a pulsed mode to different experimental setups. These are for instance traps to measure
In order to test the predictions of quantum-electrodynamics (QED) the g-factor of the bound electron in hydrogen-like
the g-factor of the bound electron or the mass of the ion. Other setups are designed to
uranium will be measured in a dedicated Penning trap. In turn, these measurements are able to deliver a new access
investigate the electronic structure of heavy, highly-charged ions in detail in slow collisions with
to fundamental constants, as for instance the mass of the electron or the fine-structure constant a.
helium atoms or with surfaces of insulators and semi-conductors.
General Information
MATS and HITRAP are international collaborations. More than 16 institutes are part of them and cooperate in the design and construction . A letter of intent
for the MATS project was submitted in April 2004 to the FAIR committee and approved . A cost review board evaluated recently very positive the financial
part of MATS. Already since spring 2004 HITRAP has been an approved midterm project of GSI and construction of the decelerator and the cooler trap
have been started in 2005. First experiments at HITRAP are scheduled for 2007.
For further information contact:
Dr. Klaus Blaum or Dr. Frank Herfurth
Address: University of Mainz, Institute of Physics,
55099 Mainz or GSI, 64291 Darmstadt