T. Ikeda

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.

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.

Density enhancement of muon beams with tapered glass tubes

We have demonstrated that the beam density of 54 MeV/c muons can be increased almost by a factor of two when a tapered glass tube is inserted coaxially along the muon beam. The observations are compared with a multiple Coulomb scattering calculation, which reproduces the observation reasonably. This technique opens a new and simple way to increase the muon intensity effectively.

Ion beam guiding with straight and curved Teflon tubes

In an effort to develop a flexible ion beam guiding scheme, the guiding capabilities of straight and curved Teflon tubes were tested with 8 keV Ar8+ ions. The tubes used were about 50 mm long and of 1 mm/2 mm inner and outer diameters. One was straight, and the others were bent with different radii of curvature corresponding to bending angles from 9.6° to 26.7°. Transmission of several tens of per cent of the injected beam was observed for the curved tubes, while transmission through the tilted straight tube vanished when the tilt was more than 7°. This demonstrates the possibility of efficient ion beam guiding with flexible insulator tubes.

Focusing Effect of MeV Muon Beam with a Tapered Capillary Method

Focusing effect of muon beam with a tapered capillary method has been investigated in a range from 4.2 to 9.2 MeV (i.e., from 30 to 45 MeV/ c in momentum). We injected the muon beam into a pair of narrowing (tapered) plates and tubes made of glass, copper and gold-coated copper, and measured the energy distribution and the profile of the muon outgoing from the outlet. The plates were tilted from an inlet of 40 mm to an outlet of 20 mm. The density enhancement was more prominent with the plates made of heavier elements. The largest beam density enhancement at 10 mm downstream of the outlet was 1.3 with the gold-coated copper narrowing plates. The enhancement was composed of muons scattered with a small angle. Their energy was slightly lost less than that of the initial beam. This effect did not depend on the surface roughness. The density enhancement with the copper narrowing tube was 1.7, where the inlet and outlet sizes were 40 mm square and 10 mm square, respectively. The spin polarization was conserved...

Guiding of a Slow Positron Beam with a Glass Capillary

Slow positron beam was injected into a non-tapered glass capillary which was tilted angle of θ from the beam axis by a movable stage. Beam profiles of the positrons transported through the capillary were observed with a phosphor screen combined with micro channel plates as a function of θ. Some fraction of positrons was deflected with the tilting angle of the capillary.

Guiding of slow highly charged ions through nanocapillaries – dynamic aspect –

We have studied the properties of guiding of Ne7+ ions through nanocapillaries in insulating PET polymers for incident energies from 3.5 to 7 keV with a two-dimensional position sensitive detector. During the intensity evolution of transmitted ions, the deflection angle of the transmitted Ne7+ ions shows a few oscillations before approaching an equilibrium value. The experimental results are interpreted in terms of a scenario where the deflection angles of transmitted ions are governed by charge patches formed on the inner wall of the capillary. In addition, the memory effect of charge patches retained from previous irradiation are studied.

High-resolution soft X-ray spectroscopy of slow highly charged ions transmitted through a microcapillary target

Abstract To detect weak X-rays with a high-resolution spectrometer, a charge-coupled device was operated in a single X-ray photon detection mode. A procedure to effectively identify single X-ray was established. In the case of 2.3 keV/u N7+ and Ne9+ incidence, X-rays emitted from ions transmitted through a Ni microcapillary target were measured with the spectrometer using the procedure of the single event mode. The signal-to-noise ratio was improved by using the single photon counting method.

Metastable states produced with beam–capillary interaction

Abstract The formation and relaxation processes of hollow atoms and related excited states of ions produced with a Ni microcapillary thin foil have been studied employing various experimental techniques. The first stage of the charge transfer from the surface to the ions was studied by using visible light measurements. On the other hand, X-ray measurements revealed the core electronic configurations of ions at the last moment of the hollow atom evolution. The overall feature of the electron capture processes in the capillary was given by the charge state distribution measurements.