1,447 research outputs found
First observation of two hyperfine transitions in antiprotonic He-3
We report on the first experimental results for microwave spectroscopy of the
hyperfine structure of antiprotonic He-3. Due to the helium nuclear spin,
antiprotonic He-3 has a more complex hyperfine structure than antiprotonic He-4
which has already been studied before. Thus a comparison between theoretical
calculations and the experimental results will provide a more stringent test of
the three-body quantum electrodynamics (QED) theory. Two out of four
super-super-hyperfine (SSHF) transition lines of the (n,L)=(36,34) state were
observed. The measured frequencies of the individual transitions are
11.12559(14) GHz and 11.15839(18) GHz, less than 1 MHz higher than the current
theoretical values, but still within their estimated errors. Although the
experimental uncertainty for the difference of these frequencies is still very
large as compared to that of theory, its measured value agrees with theoretical
calculations. This difference is crucial to be determined because it is
proportional to the magnetic moment of the antiproton.Comment: 8 pages, 6 figures, just published (online so far) in Physics Letters
Systematic study of the decay rates of antiprotonic helium states
A systematic study of the decay rates of antiprotonic helium (\pbhef and
\pbhet) at CERN AD (Antiproton Decelerator) has been made by a laser
spectroscopic method. The decay rates of some of its short-lived states, namely
those for which the Auger rates are much larger than
their radiative decay rates ( s),
were determined from the time distributions of the antiproton annihilation
signals induced by laser beams, and the widths of the atomic resonance lines.
The magnitude of the decay rates, especially their relation with the transition
multipolarity, is discussed and compared with theoretical calculations.Comment: 6 pages, 5 figures, and 1 tabl
Plans for Hadronic Structure Studies at J-PARC
Hadron-physics projects at J-PARC are explained. The J-PARC is the
most-intense hadron-beam facility in the multi-GeV high-energy region. By using
secondary beams of kaons, pions, and others as well as the primary-beam proton,
various hadron projects are planned. First, some of approved experiments are
introduced on strangeness hadron physics and hadron-mass modifications in
nuclear medium. Second, future possibilities are discussed on hadron-structure
physics, including structure functions of hadrons, spin physics, and
high-energy hadron reactions in nuclear medium. The second part is discussed in
more details because this is an article in the hadron-structure session.Comment: 10 pages, LaTeX, 20 eps files, to be published in Journal of Physics:
Conference Series (JPCS), Proceedings of the 24th International Nuclear
Physics Conference (INPC 2010), Vancouver, Canada, July 4 - 9, 201
Precise laser spectroscopy of the antiprotonic helium atom and CPT test on antiproton mass and charge
We have measured twelve transition frequencies of the antiprotonic helium
atom (pbar-He+) with precisions of 0.1--0.2 ppm using a laser spectroscopic
method. The agreement between the experiment and theories was so good that we
can put a limit on the proton-antiproton mass (or charge) difference. The new
limit is expected to be much smaller than the already published value, 60 ppb.Comment: proceeding of the conference, "PANIC02
Hyperfine structure of antiprotonic helium revealed by a laser-microwave-laser resonance method
Using a newly developed laser-microwave-laser resonance method, we observed a
pair of microwave transitions between hyperfine levels of the
state of antiprotonic helium. This experiment confirms the quadruplet hyperfine
structure due to the interaction of the antiproton orbital angular momentum,
the electron spin and the antiproton spin as predicted by Bakalov and Korobov.
The measured frequencies of GHz and
GHz agree with recent theoretical
calculations on a level of .Comment: 4 pages, 4 figures, 1 tabl
Near-Infrared Adaptive Optics Spectroscopy of Binary Brown Dwarf HD 130948B and C
We present near-infrared spectroscopy of low-mass companions in a nearby
triple system HD 130948 (Gliese 564, HR 5534). Adaptive optics on the Subaru
Telescope allowed spectroscopy of the individual components of the 0".13 binary
system. Based on a direct comparison with a series of template spectra, we
determined the spectral types of HD 130948B and C to be L4 +- 1. If we take the
young age of the primary star into account (0.3-0.8 Gyr), HD 130948B and C most
likely are a binary brown dwarf system.Comment: 6 pages, 3 figures, accepted for publication in ApJ Letter
Selected topics on Hadrons in Nuclei
In this talk we report on selected topics on hadrons in nuclei. The first
topic is the renormalization of the width of the in a nuclear
medium. This is followed by a short update of the situation of the in
the medium. The investigation of the properties of in the nuclear
medium from the study of the reaction is also addressed, as
well as properties of X,Y,Z charmed and hidden charm resonances in a nuclear
medium. Finally we address the novel issue of multimeson states.Comment: Talk at the International Nuclear Physics Conference, Vancouver, July
201
Preliminary Results from Recent Measurements of the Antiprotonic Helium Hyperfine Structure
We report on preliminary results from a systematic study of the hyperfine
(HF) structure of antiprotonic helium. This precise measurement which was
commenced in 2006, has now been completed. Our initial analysis shows no
apparent density or power dependence and therefore the results can be averaged.
The statistical error of the observable M1 transitions is a factor of 60
smaller than that of three body quantum electrodynamic (QED) calculations,
while their difference has been resolved to a precision comparable to theory (a
factor of 10 better than our first measurement). This difference is sensitive
to the antiproton magnetic moment and agreement between theory and experiment
would lead to an increased precision of this parameter, thus providing a test
of CPT invariance.Comment: 6 pages, 4 figure
Strong interaction studies with kaonic atoms
The strong interaction of antikaons (K-) with nucleons and nuclei in the low
energy regime represents an active research field connected intrinsically with
few-body physics. There are important open questions like the question of
antikaon nuclear bound states - the prototype system being K-pp. A unique and
rather direct experimental access to the antikaon-nucleon scattering lengths is
provided by precision X-ray spectroscopy of transitions in low-lying states of
light kaonic atoms like kaonic hydrogen isotopes. In the SIDDHARTA experiment
at the electron-positron collider DA?NE of LNF-INFN we measured the most
precise values of the strong interaction observables, i.e. the strong
interaction on the 1s ground state of the electromagnetically bound K-p atom
leading to a hadronic shift and a hadronic broadening of the 1s state. The
SIDDHARTA result triggered new theoretical work which achieved major progress
in the understanding of the low-energy strong interaction with strangeness.
Antikaon-nucleon scattering lengths have been calculated constrained by the
SIDDHARTA data on kaonic hydrogen. For the extraction of the isospin-dependent
scattering lengths a measurement of the hadronic shift and width of kaonic
deuterium is necessary. Therefore, new X-ray studies with the focus on kaonic
deuterium are in preparation (SIDDHARTA2). Many improvements in the
experimental setup will allow to measure kaonic deuterium which is challenging
due to the anticipated low X-ray yield. Especially important are the data on
the X-ray yields of kaonic deuterium extracted from a exploratory experiment
within SIDDHARTA.Comment: Proc. Few Body 21, 4 pages, 2 figure
Three Dimensional Annihilation Imaging of Antiprotons in a Penning Trap
We demonstrate three-dimensional annihilation imaging of antiprotons trapped
in a Penning trap. Exploiting unusual feature of antiparticles, we investigate
a previously unexplored regime in particle transport; the proximity of the trap
wall. Particle loss on the wall, the final step of radial transport, is
observed to be highly non-uniform, both radially and azimuthally. These
observations have considerable implications for the production and detection of
antihydrogen atoms.Comment: Invited Talk at NNP03, Workshop on Non-Neutral Plasmas, 200
- …