PROCEEDINGS OF THE WORKSHOP ON COLD ANTIMATTER PLASMAS AND APPLICATION TO FUNDAMENTAL PHYSICS
1037(2008); http://dx.doi.org/10.1063/1.2977857View Description Hide Description
The formation of the antihydrogen beam in the AEGIS experiment through the use of inhomogeneous electric fields is discussed and simulation results including the geometry of the apparatus and realistic hypothesis about the antihydrogen initial conditions are shown. The resulting velocity distribution matches the requirements of the gravity experiment. In particular it is shown that the inhomogeneous electric fields provide radial cooling of the beam during the acceleration.
1037(2008); http://dx.doi.org/10.1063/1.2977836View Description Hide Description
In this talk I shall explain some basic concepts of baryogenesis and leptogenesis theory, and a new idea of experimental method of verification of fundamental ingredients of leptogenesis theory; the Majorana nature and the absolute magnitude of neutrino masses. Both of these are important to the quest of physics beyond the standard theory, and have far reaching implications irrespective of any particular medel of leptogenesis. If this new method works ideally, there is even a further possibility of detecting relic neutrinos.
1037(2008); http://dx.doi.org/10.1063/1.2977842View Description Hide Description
Apart from the suspected violation of the CPT invariance, we might expect if the measurements of antihydrogen atoms provide testing Weak Equivalence Principle (WEP) in the gravitational phenomena. We start with how its violation can be related to the expected idea of unification of particle physics and gravitation, an attempt beyond the standard theories, including general relativity of Einstein. A particular emphasis will be placed on the issue of an accelerating universe, a rather recent development since nearly 10 years ago, suggesting a strong motivation toward attempts beyond the conventional concepts of the traditional cosmology. We face today's version of the cosmological constant problem. A candidate of the new ingredient appears to be provided by a scalar field, sometimes under the names like quintessence or dark‐energy. In this article, we discuss the subject from a point of view of a more theoretical approach based on the scalar‐tensor theory of gravitation. By exploiting the concepts of conformal transformations and conformal frames unique to this type of approach, we show that a successful understanding of the observed cosmological acceleration entails an unexpected outcome of breakdown of WEP, which may show up as a distinct behavior between hydrogen and antihydrogen in the gravitational influence, from a further wider perspective including a vector field as well. We intended to introduce most of the new concepts as plainly and briefly as possible, according to the nature of the talk. On the other hand, however, we find it also useful to go into some more details, depending on the interests of individuals among the audience. For a compromise, we decided to add a number of footnotes which were not delivered during the presentation, but might be helpful in the proceedings published later.
1037(2008); http://dx.doi.org/10.1063/1.2977854View Description Hide Description
We propose to use the charge exchange reaction of antiprotons with positronium atoms in order to produce antihydrogen atoms, and ions. The ions can be cooled down to μK temperatures and then ionized to recover an ultra slow neutral atom. Its acceleration is then measured by time of flight. Results on the conversion of slow positrons into positronium are presented. This is a first step towards the creation of a dense cloud of positronium atoms to be used as a target for the antiprotons. The source of positrons is based on a 6 MeV industrial electron linac with 0.2 mA average current to be installed in CEA‐Saclay. Equipped with a tungsten target and a moderator, it is aimed at producing rates of order slow positrons.
1037(2008); http://dx.doi.org/10.1063/1.2977855View Description Hide Description
Positronium is an ideal system for the research of the bound state QED. New precise measurement of orthopositronium decay rate has been performed with an accuracy of 150 ppm, and the result combined with the last three is It is the first result to validate the 2nd order correction. The Hyper Fine Splitting of positronium is sensitive to the higher order corrections of the QED prediction and also to the new physics beyond Standard Model via the quantum oscillation into virtual photon. The discrepancy of 3.5σ is found recently between the measured values and the QED prediction It might be due to the contribution of the new physics or the systematic problems in the previous measurements: (non‐thermalized Ps and non‐uniformity of the magnetic field). We propose new methods to measure HFS precisely without the these uncertainties.
1037(2008); http://dx.doi.org/10.1063/1.2977856View Description Hide Description
The 3γ decay of spin‐aligned triplet positronium can be used to test ( and ) invariance in the lepton sector. The angular correlation is used for this test, where s is the positronium spin and are the γ momenta.
We designed a new detector to test this symmetry at the level. This detector consists of a magnet, a tagging and o‐Ps creation system, γ‐ray detectors, and a turntable. The detector construction is almost finished and data acquisition will begin in this spring.
With a similar detector, the symmetry can be also tested. In this case, the angular correlation is used. This test will be started after the test is finished.
1037(2008); http://dx.doi.org/10.1063/1.2977858View Description Hide Description
The use of positron plasmas to produce intense positron pulses has made it possible to create relatively large instantaneous positronium densities. This in turn provides an opportunity to perform improved precision spectroscopy measurements on positronium that will be limited by systematic rather than statistical effects which will improve present QED positronium tests by orders of magnitude. Further increases in the positronium density will lead to the production of a positronium Bose‐Einstein condensate, further increasing the accuracy of such measurements and making it possible to study the phase diagram of a matter‐antimatter condensate for the first time.
1037(2008); http://dx.doi.org/10.1063/1.2977859View Description Hide Description
Recent research is described that exploits nonneutral plasma techniques to develop new tools to accumulate, manipulate and store antimatter and to make cold, bright antiparticle beams. Progress is described in three areas: radial compression of single‐component plasmas using rotating electric fields in a novel, strong‐drive regime; experiments and complementary theoretical modeling of the extraction of antiparticle beams with small transverse spatial extent from single‐component plasmas; and work to develop a multicell trap to increase, by orders of magnitude, the capacity for antiparticle storage. Potential applications of these tools and challenges for future research are discussed.
1037(2008); http://dx.doi.org/10.1063/1.2977860View Description Hide Description
Control of the radial profile of trapped antiproton clouds is critical to trapping antihydrogen. We report detailed measurements of the radial manipulation of antiproton clouds, including areal density compressions by factors as large as ten, achieved by manipulating spatially overlapped electron plasmas. We show detailed measurements of the near‐axis antiproton radial profile, and its relation to that of the electron plasma. We also measure the outer radial profile by ejecting antiprotons to the trap wall using an octupole magnet.
1037(2008); http://dx.doi.org/10.1063/1.2977830View Description Hide Description
Low energy non‐neutral electron plasmas were confined with an axially symmetric magnetic mirror field and an electrostatic potential to investigate the basic confinement properties of a simple magnetic mirror trap. As expected the confinement time became longer as a function of the mirror ratio. The axial electrostatic oscillations of a confined electron plasma were also observed. Obtained results suggested an improved scheme to accumulate low energy charged particles with the use of a magnetic mirror field, which would enable the investigation of electron‐positron plasmas.
1037(2008); http://dx.doi.org/10.1063/1.2977831View Description Hide Description
We have developed a hybrid method to treat charged‐particle impact ionization of complex atoms and ions. The essential idea is to describe the interaction between a fast projectile and the target perturbatively, up to second order, while the initial bound state and the ejected‐electron—residual‐ion interaction can be handled via a convergent R‐matrix with pseudo‐states (close‐coupling) expansion. Example results for ionization of the heavy noble gases (Ne—Xe) by positron and electron impact are presented. The general scheme for a distorted‐wave treatment of ionization by heavy‐particle impact is described.
1037(2008); http://dx.doi.org/10.1063/1.2977832View Description Hide Description
The structure of matter is related to symmetries at every level of study. CPT symmetry is one of the most important laws of field theory: it states the invariance of physical properties when one simultaneously changes the signs of the charge and of the spatial and time coordinates of free elementary particles. Although in general opinion CPT symmetry is not violated in Nature, there are theoretical attempts to develop CPT‐violating models. The Antiproton Decelerator at CERN has been built to test CPT invariance. The ASACUSA experiment compares the properties of particles and antiparticles by studying the antiprotonic helium atom via laser spectroscopy and measuring the mass, charge and magnetic moment of the antiproton as compared to those of the proton.
1037(2008); http://dx.doi.org/10.1063/1.2977833View Description Hide Description
The ASACUSA collaboration has carried out laser spectroscopy of an antiprotonic helium atom ( a Coulomb three‐body system consisted of an antiproton, electron, and a helium nucleus) at CERN's Antiproton Decelerator facility and measured transition frequencies of By comparing the measured frequencies with three‐body QED calculations, the antiproton‐to‐electron mass ratio was determined. We recently developed a new laser system consisting of single‐mode continuous‐wave lasers, a femtosecond optical frequency comb, a pulse‐amplified dye laser, and a chirp compensation, and achieved a precision of on the transition frequencies, which was about one order of magnitude improvement. The comparison of the measured frequencies and the three‐body QED calculations yielded the antiproton‐to‐electron mass ratio of Combined with a constraint on the proton and antiproton charge‐to‐mass ratio of the TRAP group, a limit on any ‐violating difference between the antiproton and proton charges and masses was also set as at a confidence level of 90%.
1037(2008); http://dx.doi.org/10.1063/1.2977834View Description Hide Description
We report preliminary results from a systematic study of the experimental conditions for a measurement of the hyperfine (HF) structure of antiprotonic helium Improvements to the laser system have increased the peak‐to‐total signal and allowed the delay of the second laser to be extended. We have completed the first experimental measurements of the relaxation collision rate between HF states, by which antiprotonic helium atoms undergo inelastic spin exchange collisions. We show that a microwave induced π—pulse between HF states is achieved and that a higher signal‐to‐noise ratio than our previous results is possible. The study was carried out at the Antiproton Decelerator (AD) at CERN.
1037(2008); http://dx.doi.org/10.1063/1.2977835View Description Hide Description
The most recent pionic—hydrogen experiment marks the completion of a whole series of measurements, the main goal of which was to provide conclusive data on pion—nucleon interaction at threshold for comparison with calculations from Chiral perturbation theory. The precision achieved for hadronic shift and broadening of 0.2% and 2%, respectively, became possible by comprehensive studies of cascade effects in hydrogen and other light exotic atoms including results from the last years of LEAR operation. In order to obtain optimum conditions for the Bragg crystal spectrometer, the cyclotron trap II has been used to provide a suitable X—ray source. To characterize the bent crystal spectrometer, the cyclotron trap has been modified to operate as an electron—cyclotron resonance source, which produces with high intensity narrow X‐ray transitions in the few keV range originating from highly charged ions.
1037(2008); http://dx.doi.org/10.1063/1.2977837View Description Hide Description
We investigate cold rubidium plasmas in a particle trap that has the unique capability to simultaneously laser‐cool and trap neutral atoms as well as to confine plasmas in magnetic fields of about three Tesla. The atom trap is a high‐field Ioffe‐Pritchard laser trap, while the plasma trap is a Ioffe‐Penning trap that traps electrons and ions in separate wells. The observed plasma dynamics is characterized by a breathing‐mode oscillation of the positive (ionic) plasma component, which feeds back on the behavior of the negative (electron) component of the plasma. At higher densities, the observed oscillations become nonlinear. The electron component has been found to undergo rapid cooling. We further report on the recombination of magnetized plasmas into Rydberg atoms in transient traps and quasi‐steady‐state traps. In transient traps, large numbers of recombined Rydberg atoms in high‐lying states are observed. In quasi‐steady‐state traps, the measured numbers of recombined atoms are lower and the binding energies higher.
1037(2008); http://dx.doi.org/10.1063/1.2977838View Description Hide Description
It is shown that several features of antihydrogen production in nested Penning traps can be described with accurate and efficient Monte Carlo simulations. It is found that cold deeply‐bound Rydberg states of antihydrogen are produced in three‐body capture in the ATRAP experiments and an additional formation mechanism ‐Rydberg charge transfer‐, particular to the nested Penning trap geometry, is responsible for the observed fast (hot) atoms. Detailed description of the numerical propagation technique for following extreme close encounters is given. An analytic derivation of the power law behavior of the field ionization spectrum is provided.
1037(2008); http://dx.doi.org/10.1063/1.2977840View Description Hide Description
We discuss aspects of antihydrogen studies, that relate to particle physics ideas and techniques, within the context of the ALPHA experiment at CERN's Antiproton Decelerator facility. We review the fundamental physics motivations for antihydrogen studies, and their potential physics reach. We argue that initial spectroscopy measurements, once antihydrogen is trapped, could provide competitive tests of CPT, possibly probing physics at the Planck Scale. We discuss some of the particle detection techniques used in ALPHA. Preliminary results from commissioning studies of a partial system of the ALPHA Si vertex detector are presented, the results of which highlight the power of annihilation vertex detection capability in antihydrogen studies.