956 research outputs found
Chiral dynamics and pionic 1s states of Pb and Sn isotopes
We calculate shifts and width of 1s and 2p states of pions bound to heavy
nuclei, using an optical potential with its s-wave interaction part based on
chiral symmetry. This potential is constructed systematically in two-loop
approximation of chiral perturbation theory. A proper treatment of the explicit
energy dependence of this potential in conjunction with gauge invariance turns
out to be very important. Results are reported for deeply bound pionic states
in Pb and Sn isotopes in comparison with the GSI dataComment: 4 pages, contribution to PANIC02, Osaka, Japan, September 30 -
October 4, 200
Observation of Non-Exponential Orbital Electron Capture Decays of Hydrogen-Like Pr and Pm Ions
We report on time-modulated two-body weak decays observed in the orbital
electron capture of hydrogen-like Pr and Pm
ions coasting in an ion storage ring. Using non-destructive single ion,
time-resolved Schottky mass spectrometry we found that the expected exponential
decay is modulated in time with a modulation period of about 7 seconds for both
systems. Tentatively this observation is attributed to the coherent
superposition of finite mass eigenstates of the electron neutrinos from the
weak decay into a two-body final state.Comment: 12 pages, 5 figure
Recommended from our members
Laser-Induced Spall Of Aluminum And Aluminum Alloys At High Strain Rates
We conducted laser-induced spall experiments aimed at studying how a material's microstructure affects the tensile fracture characteristics at high strain rates (> 10(6) s(-1)). We used the Z-Beamlet Laser at Sandia National Laboratory to drive shocks and to measure the spall strength of aluminum targets with various microstructures. The targets were recrystallized, high-purity aluminum (Al-HP RX), recrystallized aluminum + 3 wt.% magnesium (Al-3Mg RX), and cold-worked aluminum + 3 wt.% magnesium (Al-3Mg CW). The Al-3Mg RX and Al-3Mg CW are used to explore the roles that solid-solution alloying and cold-work strengthening play in the spall process. Using a line-VISAR (Velocity Interferometer System for Any Reflector) and analysis of recovered samples, we were able to measure spall strength and determine failure morphology in these targets. We find that the spall strength is highest for Al-HP RX. Analysis reveals that material grain size plays a vital role in the fracture morphology and spall strength results.Mechanical Engineerin
Experimental Investigations and Technical Design for The Time-OF-Flight Detectors in the CR at FAIR
Projectile fragmentation of 129Xe at Elab=790 AMeV
We have measured production yields and longitudinal momentum distributions of
projectile-like fragments in the reaction 129Xe + 27Al at an energy of Elab=790
AMeV. Production cross sections higher than expected from systematics were
observed for nuclei in the neutron-deficient tails of the isotopic
distributions. A comparison with previously measured data from the
fragmentation of 136Xe ions shows that the production yields strongly depend on
the neutron excess of the projectile with respect to the line of
beta-stability. The momentum distributions exhibit a dependence on the fragment
neutron-to-proton ratio in isobaric chains, which was not expected from
systematics so far. This can be interpreted by a higher excitation of the
projectile during the formation of neutron-deficient fragments.Comment: 21 pages, 8 figures, 1 tabl
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 in Sn were preferentially
observed using the Sn(,He) 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 . The observed enhancement
of over the free value ()
indicates a reduction of the chiral order parameter, , at the normal nuclear density, .Comment: 4 pages including 3 postscript figures, RevTeX 4 with multirow.sty,
submitted to Physical Review Letter
A Measurement of the Coulomb Dissociation of 8B at 254 MeV/nucleon and the 8B Solar Neutrino Flux
We have measured the Coulomb dissociation of 8B into 7Be and proton at 254
MeV/nucleon using a large-acceptance focusing spectrometer. The astrophysical
S17 factor for the 7Be(p,gamma)8B reaction at E{c.m.} = 0.25-2.78 MeV is
deduced yielding S17(0)=20.6 \pm 1.2 (exp.) \pm 1.0 (theo.) eV-b.
This result agrees with the presently adopted zero-energy S17 factor obtained
in direct-reaction measurements and with the results of other
Coulomb-dissociation studies performed at 46.5 and 51.2 MeV/nucleon.Comment: paper to be published in Phys. Rev. Lett. 3 figures. New Version
fixes formatting problems with the figures only. There are no other change
On the discovery of doubly-magic Ni
The paper reports on the first observation of doubly-magic Nickel-48 in an
experimental at the SISSI/LISE3 facility of GANIL. Four Nickel-48 isotopes were
identified. In addition, roughly 100 Nickel-49, 50 Iron-45, and 290 Chromium-42
isotopes were observed. This opens the possibility to search for two-proton
emission from these nuclei.Comment: 4 pages, 3 figures, accepted for publication in Phys. Rev. Let
eta-Nucleus interactions and in-medium properties of N*(1535) in chiral models
The properties of eta-nucleus interaction and their experimental consequences
are investigated with eta-nucleus optical potentials obtained by postulating
the N*(1535) dominance for eta-N system. The N*(1535) properties in nuclear
medium are evaluated by two kinds of chiral effective models based on distinct
pictures of N*(1535). We find that these two models provide qualitatively
different optical potentials of the eta meson, reflecting the in-medium
properties of N*(1535) in these models. In order to compare these models in
physical observables, we calculate spectra of (d,3He) reactions for the eta
mesic nucleus formation with various kinds of target nuclei. We show that the
(d,3He) spectra obtained in these models are significantly different and are
expected to be distinguishable in experiments.Comment: 24 pages, 8 figure
- …