Martin Winkler

Precision spectroscopy of pionic 1s states of Sn nuclei and evidence for partial restoration of chiral symmetry in the nuclear medium

Deeply bound 1s states of pi(-) in (115,119,123)Sn were preferentially observed using the Sn(d,3He) pion-transfer reaction under the recoil-free condition. The 1s binding energies and widths were precisely determined and were used to deduce the isovector parameter of the s-wave pion-nucleus potential to be b1=-(0.115+/-0.007)m(-1)(pi). The observed enhancement of |b(1)| over the free piN value (b(free)1/b1=0.78+/-0.05) indicates a reduction of the chiral order parameter, f*pi(rho)2/f2pi approximately 0.64, at the normal nuclear density, rho=rho(0).

Electron Screening Effects on a-decay

An open problem in Nuclear Astrophysics concerns the understanding of electron‐screening effects on nuclear reaction rates at stellar energies. In this framework, we have proposed to investigate the influence of the electron cloud on α‐decay by measuring Q‐values and α‐decay half‐lives of fully stripped, H‐like and He‐like ions. These kinds of measurements have been feasible just recently for highly‐charged radioactive nuclides by fragmentation of 238U at relativistic energies at the FRS‐ESR facility at GSI. In this way it is possible to produce, efficiently separate and store highly‐charged α‐emitters. Candidates for the proposed investigation were carefully selected and will be studied by using the Schottky Mass Spectroscopy technique. In order to establish a solid reference data set, lifetimes and Qα‐value measurements of the corresponding neutrals have been performed directly at the FRS, by implanting the separated ions into an active Silicon stopper.

Mass and Lifetime Measurements in Storage Rings

Masses of nuclides covering a large area of the chart of nuclides can be measured in storage rings where many ions circulate at the same time. In this paper the recent progress in the analysis of Schottky mass spectrometry data is presented as well as the technical improvements leading to higher accuracy for isochronous mass measurements with a time‐of‐flight detector. The high sensitivity of the Schottky method down to single ions allows to measure lifetimes of nuclides by observing mother and daughter nucleus simultaneously. In this way we investigated the decay of bare and H‐like 140Pr. As we could show the lifetime can be even shortened compared to those of atomic nuclei despite of a lower number of electrons available for internal conversion or electron capture.All these techniques will be implemented with further improvements at the storage rings of the new FAIR facility at GSI in the future.Masses of nuclides covering a large area of the chart of nuclides can be measured in storage rings where many ions circulate at the same time. In this paper the recent progress in the analysis of Schottky mass spectrometry data is presented as well as the technical improvements leading to higher accuracy for isochronous mass measurements with a time‐of‐flight detector. The high sensitivity of the Schottky method down to single ions allows to measure lifetimes of nuclides by observing mother and daughter nucleus simultaneously. In this way we investigated the decay of bare and H‐like 140Pr. As we could show the lifetime can be even shortened compared to those of atomic nuclei despite of a lower number of electrons available for internal conversion or electron capture.All these techniques will be implemented with further improvements at the storage rings of the new FAIR facility at GSI in the future.

Survey on Remote Handling Logistics for Super-FRS

Remote Handling (RH) systems are now frequently used to conduct inspections and maintenance in hazardous environments. New particle accelerator facilities present unique logistic challenges due to high radiation levels, a hazardous environment and heavy loads. The Facility for Antiproton and Ion Research (FAIR) will deliver a beam of all ions up to uranium with intensities up to 1012 238U ions/s, which will cause high levels of radiation during operation so human access is limited. This paper contains a survey on RH logistics for existing High Intensity Beam (HIB) facilities to determine state of the art RH practices and to draw a conclusion based on the analysis. The second part of this paper presents a detailed study of beam losses, the radiation environment, RH logistic challenges and some proposed solutions for Super-FRS. This paper will also suggest a Systems Engineering (SE) approach for developing Super-FRS RH logistics.

New Developments for Isochronous Mass Measurements of Short‐Lived Nuclei

The combination of the in‐flight separator FRS and the storage‐ring ESR at GSI offers unique possibilities for high accuracy mass and lifetime measurements of bare and few‐electron fragments. Operating the ESR in the isochronous mode allows for measurements of revolution frequencies of stored ions without cooling. Isochronous Mass Spectrometry (IMS) can be applied to fragments with half‐lives as short as several tens of microseconds. Newly developed magnetic rigidity tagging increases the resolving power of IMS to about 500000. IMS can be used to measure masses of nuclei with rates even lower than one ion per day, a property also needed for the purpose of the ILIMA project at the future facility FAIR.

Observation of Pionic 1s States in Sn Nuclei and Its Implications on Chiral Symmetry Restoration

We observed deeply bound π - is states in 1 1 5 , 1 1 9 , 1 2 3 Sn for the first time in 1 1 6 , 1 2 0 , 1 2 4 Sn(d3,He) reactions at recoil free conditions to determine the 1s binding energies and the widths precisely. A preliminary result is used to deduce the isovector scattering amplitude as b 1 = 0.115 ′ 0.005 m - 1 π . The observed enhancement of b 1 over the free πN value infers 35% reduction of f 2 π at the normal nuclear density. ρ = 0.17 fm - 3 .

Super-FRS Target Area Remote Handling: Scenario and Development

The Super-FRS, Superconducting Fragment Separator, is a unique machine that presents several challenging technical problems. One of these is regarding how to conduct maintenance in the target area where high levels of radiation will be generated and human access is forbidden. To address this problem the use of a remote maintenance system is foreseen. The objective of this paper is to develop a systems engineering (SE) research and development (R&D) approach suitable to develop the Super-FRS Target Area Remote Maintenance Systems (TARMS) and the RH design adaptation of the components in the target area. The Super-FRS target area is described in detail in order to introduce the need for a remote maintenance system. Components in the target area are classified by adopting ITER RH maintenance classification. The general scenario of remote handling and the current target area remote maintenance system are described. Finally, the proposed systems engineering approach is presented.

Super-FRS slit system and possible passive cooling techniques

X− and Y− position slit systems will be used to stop the unwanted charge states of the primary beam and fragments produced at the reaction target of the Super-FRS at the FAIR facility, GSI. In the case of the most frequently used fission reaction of U beam at 1.5 GeV/u on C target (2.5 g/cm), one of the lowest charge states of U fragments produced at the target may reach one of the X-slits with an energy of about 1.3 GeV/u with a maximum power of 500 W. The basis of the Super-FRS X− and Y− slit systems are two DENSIMET R ©185 (97% Tungsten, 2% Nickel and 1% Iron) metal blocks, which have to move in a vacuum chamber in horizontal direction (0 − 400 mm) and in vertical direction(0 − 200 mm), respectively. Due to the highly radioactive environment,

A CONCEPTUAL DESIGN STUDY OF A NEXT GENERATION SEPARATOR FOR THE IN-FLIGHT SEPARATION OF SUPERHEAVY NUCLEI

After more than 25 years of the successful operation of SHIP in heavy and superheavy element research, it is sue time for the developement of a next-generation in-flight separator for fusion and transfer products, primarily for heavy and superheavy elements. This work is triggered by new developments including accelerators for beams of highest intensity, the availability of strong beams of radioactive isotopes at near coulomb barrier energies, and the recent developement for efficient ion catcher-cooler systems with the capability of mass identification and measurement.

Investigation of the Dipole Response in Exotic Nuclei-Experiments at the LAND-(RB)-B-3 Setup

We present experimental results on the electromagnetic excitation of neutron-rich nickel isotopes, making use of the (RB)-B-3-LAND setup at GSI. Exotic beams were produced at approximately 500 MeV/u and their reactions were studied in inverse kinematics. Integral cross sections for Ni-58 are discussed and compared to previous data, providing a validation of our experimental method. The El excitation-energy distribution of the unstable Ni-68 is presented as well, showing an excess in cross section in the 1n decay channel when compared only with a typical Giant Dipole Resonance.