Y. Yamazaki

Slow RI-beams from projectile fragment separators

Abstract The projectile fragment separator provides a wide variety of short-lived RI-ions with less restrictions on their chemical property or lifetime limit. The beam energy and quality is, however, not adequate for low-energy beam experiments, in particular for trapping experiments. Recently, one has proposed to obtain a low-energy beam from an energetic RI-beam leaving a projectile fragment separator by using a large gas-catcher and an rf ion-guide system. In off-line and in on-line test experiments, the principle of the rf ion-guide was proven. An overall efficiency of 0.2% for 70 MeV/u 8 Li from the RIKEN projectile fragment separator (RIPS) was obtained so far.

Production of a microbeam of slow highly charged ions with a tapered glass capillary

The authors have developed a method to produce a microbeam of slow highly charged ions based on a self-organized charge-up inside a tapered glass capillary. A transmission of 8keV Ar8+ beam through the capillary 5cm long with 800∕24μm inlet/outlet inner diameters was observed stably for more than 1200s. The transmitted beam had the same size as the outlet with a beam density enhancement of approximately 10 and a divergence of ±5mrad. The initial beam was guided through a capillary tilted by as large as ±100mrad, and it still kept the incident charge.

A source of antihydrogen for in-flight hyperfine spectroscopy

Antihydrogen, a positron bound to an antiproton, is the simplest antiatom. Its counterpart—hydrogen—is one of the most precisely investigated and best understood systems in physics research. High-resolution comparisons of both systems provide sensitive tests of CPT symmetry, which is the most fundamental symmetry in the Standard Model of elementary particle physics. Any measured difference would point to CPT violation and thus to new physics. Here we report the development of an antihydrogen source using a cusp trap for in-flight spectroscopy. A total of 80 antihydrogen atoms are unambiguously detected 2.7 m downstream of the production region, where perturbing residual magnetic fields are small. This is a major step towards precision spectroscopy of the ground-state hyperfine splitting of antihydrogen using Rabi-like beam spectroscopy.

Tank circuit model applied to particles in a Penning trap

The equivalent circuit model is used to describe analytically the coupling process of the center of mass motion of a cloud of particles in a Penning trap. From the response of this coupled circuit to white noise a way of nondestructively diagnosing the number of trapped particles is given which is valid for all values of this quantity. Experimental results are presented and compared with this analysis.

Space-charge effects in the catcher gas cell of a rf ion guide

Slow radioactive ion beams have been produced with an overall efficiency of 4% by thermalizing energetic ions produced by a projectile fragment separator in a He-gas cell and guiding them to a vacuum vessel by dc and rf fields. Space charge was observed to have a limiting effect. Since the ionization of He atoms by energetic ions creates a region of high space charge, many thermalized ions of interest are pushed toward the walls of the gas cell. Such losses have been investigated for different incoming ion intensities.

High-precision comparison of the antiproton-to-proton charge-to-mass ratio

Invariance under the charge, parity, time-reversal (CPT) transformation is one of the fundamental symmetries of the standard model of particle physics. This CPT invariance implies that the fundamental properties of antiparticles and their matter-conjugates are identical, apart from signs. There is a deep link between CPT invariance and Lorentz symmetry—that is, the laws of nature seem to be invariant under the symmetry transformation of spacetime—although it is model dependent. A number of high-precision CPT and Lorentz invariance tests—using a co-magnetometer, a torsion pendulum and a maser, among others—have been performed, but only a few direct high-precision CPT tests that compare the fundamental properties of matter and antimatter are available. Here we report high-precision cyclotron frequency comparisons of a single antiproton and a negatively charged hydrogen ion (H−) carried out in a Penning trap system. From 13,000 frequency measurements we compare the charge-to-mass ratio for the antiproton to that for the proton and obtain . The measurements were performed at cyclotron frequencies of 29.6 megahertz, so our result shows that the CPT theorem holds at the atto-electronvolt scale. Our precision of 69 parts per trillion exceeds the energy resolution of previous antiproton-to-proton mass comparisons as well as the respective figure of merit of the standard model extension by a factor of four. In addition, we give a limit on sidereal variations in the measured ratio of <720 parts per trillion. By following the arguments of ref. 11, our result can be interpreted as a stringent test of the weak equivalence principle of general relativity using baryonic antimatter, and it sets a new limit on the gravitational anomaly parameter of < 8.7 × 10−7.

Ion irradiation in liquid of μm3 region for cell surgery

We present here a cell surgery scheme involving selective inactivation or disruption of cellular structures. Energetic ions are injected into a cell through a tapered glass capillary like a microinjection method. A slight but essential difference from microinjection is that a thin window is prepared at the outlet so that no liquid material can flow in or back through the outlet while still allowing energetic ions to penetrate into the cell. An ∼MeV He ion beam from such a capillary having 10μm outlet diameter inactivated a selected volume (∼μm3) of fluorescent molecules located in a HeLa cell nucleus.

Stabilized Hollow Atoms (Ions) Produced with Multiply Charged Ions Passed through Microcapillaries.

Ions of 9 keV/u Ne 9+ are impinged upon a microcapillary target along the capillary axis. X-rays emitted from the projectile downstream of the target show that a part of ions are in multiply excited states keeping a K-shell orbital open, i.e., hollow atoms (ions) are extracted in vacuum . Further, a considerable fraction of them are in extremely stabilized states with lifetimes of ∼ns which is more than 10 6 times longer than typical lifetimes of a Ne K-hole. A theoretical prediction suggests that core configurations with high spin multiplicities such as 1s2s2p 4 P are potential candidates of the stabilized fraction.

Resonant coherent excitation of 390 MeV/u Ar ions planar channeled in Si crystals

Resonant coherent excitation of the 1s electron to na 2 states in a hydrogen-like ion was studied through measurements of the survived fraction of 390 MeV/u Ar 17a planar channeled in a Si crystal. Adopting a totally depleted Si surface barrier detector as a target crystal, the charge state of the individual emerged ion was measured in coincidence with the energy deposition in the target. By changing the incident direction along theO2 20 U ,O 004 U, andO1 11 Uplanes, a series of clear resonances were observed as the decrease in the survived charge fraction due to higher electron loss probability for the excited state. Each resonance profile reflects energy splitting of the na 2 manifold originated from l‐ s interaction and Stark eAect due to the crystal field. From the correlation between the energy loss and survived charge fraction, transition energy as a function of the ion trajectory amplitude is deduced which is in good agreement with calculated results. ” 1998 Elsevier Science B.V. All rights reserved.

Enhanced ferromagnetic moment in Co-doped BiFeO3 thin films studied by soft x-ray circular dichroism

BiFeO3 (BFO) shows both ferroelectricity and magnetic ordering at room temperature, but its ferromagnetic component, which is due to spin canting, is negligible. Substitution of transition-metal atoms such as Co for Fe is known to enhance the ferromagnetic component in BFO. In order to reveal the origin of such magnetization enhancement, we performed soft x-ray absorption spectroscopy (XAS) and soft x-ray magnetic circular dichroism (XMCD) studies of BiFe1−xCoxO3 (x = 0 to 0.30) (BFCO) thin films grown on LaAlO3(001) substrates. The XAS results indicated that the Fe and Co ions are in the Fe3+ and Co3+ states. The XMCD results showed that the Fe ions show ferromagnetism, while the Co ions are antiferromagnetic at room temperature. The XAS and XMCD measurements also revealed that part of the Fe3+ ions are tetrahedrally co-ordinated by oxygen ions but that the XMCD signals of the octahedrally coordinated Fe3+ ions increase with Co content. The results suggest that an impurity phase such as the ferrimagnetic...