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Tapered glass capillary optics was utilized to produce MeV ion microbeams at the RIKEN Pelletron facility. A microbeam of 3 MeV He ions was used to irradiate HeLa cells and demonstrated an ion track consisting of double strand break points in the cell nucleus. A new microbeam line was developed with profile measurements of 2.8 MeV H+ microbeams in the atmosphere, using image recognition and knife-edge methods. After the suppression of the halo component in the microbeam, a smaller beam size was measured to be approximately 40 μm for the irradiation distance of 1 mm, which satisfied requirements of the planned applications.

We measured laser microbeam (18 µm) profiles of tilted glass capillary at wavelength 375 nm. The profile intensity, width and beam guided angle were obtained and results show guiding effect of the capillary optics.

Production of ion microbeams using tapered glass capillary optics was introduced more than 10 years ago. This technique has drawn attention in terms of both its peculiar transmission features and application to ion beam analysis. The transmission mechanism based on a self-organized charge-up process for keV-energy ions was observed for the first time in an experiment using a multitude of nanometer-sized capillaries in a polymer foil. The same mechanism can be seen for the transmission of keV ions through a single tapered glass capillary. The transmission experiments with keV ions showed a delayed transmission, focusing effects, guiding effects, and formation of microbeams. Experiments using MeV-energy ions always aim at applications of microbeam irradiation for material analysis, surface modification, cell surgery, and so on. In this article, the applications of MeV ion microbeams, including the fabrication method of the glass capillary, are reviewed, as well as the experimental and theoretical studies for the transmission mechanisms of keV/MeV ions.

The transmission of an ultraviolet-laser microbeam through a tapered glass capillary was investigated. We measured microbeam profiles using fluorescent beads and obtained smaller spots for smaller ...

Straight and curved glass capillaries were tested for the guiding of 8 keV Ar 8+ ion beams. The straight capillary was about 50 mm long and 0.87 mm/1.1 mm in inner/outer diameter. One of the two curved capillaries was similar, but was curved with a 270 mm radius. The other was 53 mm long, had diameters of 2.34 mm/2.99 mm, and was curved with a 150 mm radius. The corresponding bending angles of the two curved capillaries were 9.6° and 17.5°, respectively. Transmission through the straight capillary disappeared when the tilt angle was larger than 5°. The curved capillaries guided the ion beams into their corresponding bending angles, which were much larger than 5°, with transmission efficiencies of a few tens percent. This demonstrates the possibility of developing a new scheme of simple small beam deflectors and related beam optics.

Synopsis Profiles of 2.8 MeV H+ microbeam extracted from a single tapered glass capillary optics were meas-ured by two methods for a future irradiation to an outer organ of insect target. The halo component was analyzed to be 575 μm in full width at half maximum (FWHM) at a plastic tracking detector CR-39 located 1 mm down-stream of the capillary. The core component was examined by knife-edge method according to the ion energies. The profiles consisting of more energy-loss events have wider FWHM, which can be reduced by Al thin layers.

We report the experimental study of 1000 eV electrons transported through a tapered borosilicate glass capillary with inlet/outlet diameters of 800 μm/100 μm and a length of 35 mm. Transmission was observed for tilt angles from −9.5° to 1.0°. For tilt angles −9.5° to −4.5° the angular distributions of the normalized intensities of transmitted electrons consisted of a single peak showing stable transmission with inelastic behavior, while for tilt angles closer to zero (−4.0° to −1.0°) the spectrum consisted of two peaks also with an inelastic nature. Interestingly, when the tilt angle was within the range −0.8° to 0°, three peaks were observed, one being the direct peak with only elastic nature, and the other two showing both inelastic and elastic behaviors.

Microbeams of visible light were studied using a tapered glass capillary. Transmittance of laser light through capillaries with different inlet and outlet diameters was measured. About several % of the transmittance was obtained and larger than 80% was achieved in combining with an optical lens. It was found that the obtained transmittance considerably depended on the capillary shape, i.e., the taper angle. Density enhancement of the extracted beam was derived and showed a strong focusing ability for the tapered glass capillary. Propagation of visible light through the capillary was discussed.

We have developed a method to produce micro/nano meter sized beams of keV energy highly charged ions (HCIs) and MeV energy protons/He ions with tapered glass capillary optics for application of surface modifications and a biological tool called “cell surgery”, respectively. The transmission through the tapered glass capillaries with inlet diameter of 0.8 mmϕ, outlet diameter from 900 nmϕ to several tens of microns and length of about 50 mm was performed using 8/64 keV Ar 8+ beams. The transmitted beams had a density enhancement of about 10 and were guided through a capillary tilted by as large as ±100 mrad. The charge state of the beams was kept during the transmission. The combination of MeV proton/He ion beams and the capillary with a thin end window at its outlet can realize pinpoint energy deposition and three-dimensional selection of the bombarding point in an arbitrary position of a living cell or in any liquid object. We demonstrated that a real biological cell, HeLa cell with the nucleus labeled by green fluorescent protein (GFP), was irradiated with the microbeam, which was prepared by 4 MeV He 2+ entering a capillary with an end window of 7.3 μm in thickness and outlet diameter of 9.6 μmϕ. The transmitted MeV ion beams had density enhancement up to 1000 according to the capillary outlet sizes, which are applicable to various material analyses employing microbeams.

We have developed a method to produce a nm sized slow highly-charged ion beam based on a self-organized charge up inside a single tapered-glass capillary. In order to investigate the characteristics of the obtained beams, the transmission of 8 keV Ar8+ beam through the capillary of 5-cm long with 800/24 μm inlet/outlet inner diameter was examined. The transmitted beam had the same size as the outlet with the beam-density enhancement of approximately 10. The initial beam was guided through a capillary tilted by as large as ±100 mrad and it still kept the incident charge. A focused ion beam of Ga+ was employed to manufacture the capillary outlet as small as several hundreds nm in diameter and fabricate a thin glass window at the capillary outlet for biological applications.

Propagation and transmission of laser beam through tapered glass capillary were investigated for light microbeams. Transmittances of laser light at 488 nm and 633 nm through capillaries were measured to be up to 15%, depending on outlet diameters. By modeling the real capillary, transmittances were calculated using taper angles obtained from shape analysis and agree well with experimental ones.

This year, a prototype of a highly sensitive beam current monitor with a High- Temperature Superconducting (HTS) SQUID and an HTS magnetic shield: HTS-SQUID monitor has been installed in the beam transport line of the RIKEN Ring Cyclotron (RRC). Unlike other existing facilities, the HTS-SQUID monitor allows us to measure the DC of highenergy heavy-ion beams nondestructively in such a way that the beams are diagnosed in real - time and the beam current extracted from the RRC can be recorded without interrupting the beam user's experiments.

A superconducting tunnel junction (STJ) is very attractive for use in high-energy-resolution photon detectors because of its small energy gap. To detect a single photon, the Josephson current of the STJ has had to be suppressed by an external magnetic field. We demonstrated an on-chip coil-integrated STJ photon detector, which excludes the external magnetic field, allowing a small device size. A normal-distribution function shape was adopted for the superconducting electrodes, which makes the magnetic field supplied to the STJ small. We devise a new superconducting photon detector by combining the above techniques. A new Josephson switching gate is also integrated on the same detector chip in order to drive an on-chip integrated coil by a persistent superconducting current. This behavior was confirmed experimentally using the technology of the fabrication process of the Nb/Al-AlOx/Nb Josephson tunnel junction.

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.

On-chip coil integrated superconducting tunnel junction (OC 2 -STJ) has been demonstrated for high performance X-ray detector. The STJ was fabricated by an improved fabrication technique based on a high quality Nb/Al/AlO x /Nb junction technology. The STJ shows high quality current–voltage characteristics with an ultra-low leakage current of a few nA at 0.4 K for 100 μm ×100 μm junction. Typical critical current of the coil was achieved more than 50 mA for 2 μm line width, which can generate a magnetic field of about 10 mT into the STJ. It was found that the OC 2 -STJ successfully responded to the irradiated 5.9 keV X-ray.

We are developing an energy-dispersive detector for UV and visible photons that uses superconducting tunnel junctions (STJs) with Al trapping layers. As a first step to achieve this, we evaluated the performance of the detector for extreme ultraviolet (EUV) photons by using a synchrotron radiation facility. We achieved an energy resolution of FWHM=17.8±0.6 eV (including electrical noise of 17.6±0.2 eV) for 55 eV EUV photons with a 100×100 μm2 STJ. The electrical noise was the main component of the energy resolution. We achieved the electrical noise of FWHM=2.1±0.1 eV for a 20×20 μm2 STJ by replacing the cables connecting the STJ to a preamplifier operated at room temperature. A stronger signal resulting from a thinner tunnel barrier will lead to better energy resolution for detecting UV and visible photons.

Superconducting tunnel junctions (STJs) are applicable to as photon detectors with an energy resolution and a high photon-counting rate. The absorption of a photon in the superconductor of the STJ generates a number of quasiparticles that is proportional to the photon energy. Especially for soft X-ray and extreme ultraviolet (EUV) applications, STJs have good performance because of their high absorption efficiency below 1 keV. We are developing an energy-dispersive photon detector for EUV radiation using STJs with Al trapping layers. We evaluated the performance of the detector for EUV photons by using the Synchrotron Facility at KEK-PF in Tsukuba, Japan. We achieved an energy resolution of FWHM=18 eV (including the external noise of 17.6 eV) for 55 eV EUV photons with a 100 × 100 μ m 2 STJ. We present details of the junction design and discuss our experiments and the results.

An estimation method of micro-meter sized laser profile created by the laser beam transmission through a tapered glass capillary is developed for the target sight-on system of ion microbeam irradiation to living cells. In our system, both the laser and the ions are designed to be transmitted through the same capillary so that the laser spot is surely on the ion track. By selecting the excitation light of a fluorescent protein in cell nucleus, the fluorescent volume can be confirmed as the targeted area.

Recently, many studies have been reported on microbeam production of keV-MeV accelerated ions using tapered glass capillaries. However, few studies about visible light with the glass capillary have been reported up to now. Preferable sizes of microbeams can be obtained by the glass capillary which may provide a new method for focusing light and for producing microbeams of visible light in addition to conventional optical lenses. We report experimental study of propagation of visible light through tapered glass capillaries towards microbeams.

We present a novel facility for micro-irradiation of living targets with ions from a 1.7 MV tandem accelerator. We show results using 1 MeV protons and 2 MeV He(2+). In contrast to common micro-irradiation facilities, which use electromagnetic or electrostatic focusing and specially designed vacuum windows, we employ a tapered glass capillary with a thin end window, made from polystyrene with a thickness of 1-2 μm, for ion focusing and extraction. The capillary is connected to a beamline tilted vertically by 45°, which allows for easy immersion of the extracted ions into liquid environment within a standard cell culture dish. An inverted microscope is used for simultaneously observing the samples as well as the capillary tip, while a stage-top incubator provides an appropriate environment for the samples. Furthermore, our setup allows to target volumes in cells within a μm(3) resolution, while monitoring the target in real time during and after irradiation.

We succeeded in separating the STJ upper electrode events from other electrode events. This study is for X-ray spectroscopy of slow ions. With a SQUID amplifier, it is clearly seen that the upper electrode signal has a sharp peak with a narrow base, while the other has a relatively gentle peak with a wide base. The difference in signal width was used to separate the upper electrode events from other electrode events. Then the X-ray spectroscopy of slow highly charged ions was carried out at RIKEN. The results are shown here.

The pulse height spectra of the substrate phonon events obtained with superconducting tunnel junctions (STJs) were examined. We compared the spectra for STJs with and without a 50-nm-thick buffer layer of aluminum-oxide on the sapphire substrate under X-ray illumination. We found-that the spectral difference was concentrated in the high-energy tail of the component, corresponding to the events absorbed within a thin skin. The effective thickness of this skin was estimated to be about 3 /spl mu/m by using the amount of difference in the spectra. We explain that the spectral difference could be caused by the selective attenuation of high-frequency phonons in the substrate and buffer layer.

We report the first demonstration of X-ray detection by using a Superconducting Tunnel Junction (STJ) with a microstrip-coil. The STJ was fabricated based on Nb/Al/AlO/sub x//Nb integration process technology using a 2 /spl mu/m design rule. Magnetic field was applied into the STJ by the microstrip-coil to suppress the dc Josephson current instead of the conventional electromagnet. The output waveform was successfully observed by irradiation of 5.9 keV X-ray under a condition of microstrip-coil current of 20 mA at 0.4 K.

The pulse-height spectrum and two-dimensional image of a 0.5 mm thick GSO scintillator were investigated for a 6 A cold neutron beam. The 31 and 81 keV peaks resulting from neutron absorption by Gd nuclei were identified in the pulse-height spectrum by using a photomultiplier tube. Images of 1.5 and 2.1 mm (FWHM) in diameter were observed for 1 and 2 mm diameter incident beams with an image intensifier and viewed by a CCD camera, corresponding to a position resolution of 1.3 mm (FWHM). The result implies that a position resolution of better than 100 μm would be achievable by employing a GSO scintillator thinner than 20 μm .

We are developing high-resolution X-ray detectors based on superconducting tunnel junctions (STJs). A two-stage superconducting quantum-interference device (SQUID) amplifier with high gain, low noise and high sensitivity was employed as a readout electronic device. We have developed the STJ readout circuit which makes it possible to optimize the STJ bias condition without disturbing the operating point of the SQUID amplifier. High-resolution X-ray detectors using our system is discussed.

X-ray detectors based on Nb/Al/AlO x /Al/Nb superconducting tunnel junctions (STJ) have been fabricated. X-ray responses of the fabricated STJs were measured by illumination with X-rays from a 55 Fe electron capture source. The energy resolution of 41, 58 and 65 eV (FWHM) at 5.9 keV were obtained for 20×20, 100×100, 200×200 μm 2 , square-shaped devices, respectively. The X-ray measurements were performed at 0.35 K using a charge-sensitive preamplifier at room temperature. We also discussed the capability to suppress the substrate phonon events using Al 2 O 3 insulation layer. An advantage for the combined use of the Al 2 O 3 insulation layer and the sapphire substrate was demonstrated.

Superconducting tunnel junctions (STJ), with a buffer layer between the silicon substrate and junction, are being developed for use as high-resolution X-ray detectors. Aluminum-oxide (Al/sub 2/O/sub 3/) is employed as the buffer layer in order to suppress the phonon mediated background from the Si substrate. The extent of phonon insulation was studied by measuring the X-ray spectra of STJs as a function of buffer layer thickness. The phonon insulation ability of Al/sub 2/O/sub 3/ was compared to that of magnesium-oxide. The Al/sub 2/O/sub 3/ layer should be a good phonon insulator, with the ability to suppress phonons with a single buffer layer.

A compact system for an STJ-based high resolution X-ray detection system using a SQUID amplifier has been developed. A noise level of less than 4.8 mV at the SQUID output pulse height of 1.2 V for Nb-based STJ signals was achieved in the temperature range of 1.7-4.2 K with good reproducibility under an external magnetic field of about 0.01 Tesla, which was applied to suppress the Josephson current of the STJ. The results show the possibility of constructing a compact STJ-based X-ray detection system with an 'on-site' low noise SQUID preamplifier.

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.

Towards production of microbeams, propagation of visible light through a tapered glass capillary has been studied. Transmittance has been measured for capillaries with different outlet diameters to be about several % and larger than 80% has been achieved in combining with the optical lens. Density enhancement of the capillary has been derived, showing the strong focusing ability of the tapered glass capillary.

Stable transmission of a sub-μm-sized Ar8+ beam of 64–104-keV energy through glass tandem optics was achieved. The optics consisted of a 4-electrode tapered capillary and a sub-μm-sized tapered capillary tip, arranged in series. To actively discharge the capillary, and thus obtain stable transmission, an electrode was applied with a mechanical relay closing at a 0.01–0.1 Hz frequency. Transmitted beams were observed for tip outlets' diameters of 0.75 and 2.0 μm. When only a 4-electrode capillary was used, a beam density enhancement with a multiplicity of 14 times of the input beam density was achieved. A transmission efficiency up to 70% was observed with good reproducibility when the electrodes were biased with appropriate voltages.

Nb-based superconducting tunnel junctions (STJs) with Al trapping layers have been developed for X-ray detectors. One applications for STJs is a low energy radiation detector having energy resolution and a high photon counting rate. STJs have good potential in the band of energies from 40 eV up to 1 keV, because STJs materials have good absorbing properties in this region. The energy resolution was measured by using the Photon Factory beamline BL-12A of High Energy Accelerator Research Organization (KEK) in Japan, and for 200 eV photon, 11 eV Full Width Half at Half Maximum (FWHM) with a 20/spl times/20 /spl mu/m/sup 2/ junction were achieved. In this article, the fabrication technique and preliminary results of measuring the response for this band of energies are reported.

International audience; Multiply charged ion beam transmission through insulating capillaries is today a very active field of research. Thanks to the work of several groups during the last five years, several features of this unexpected process have been evidenced. The open challenge is to understand and control the self-organized charging-up of the capillary walls, which leads finally to the ion transmission. Up to now, the specific charge distribution on the inner surface, as well as the dynamics of the build-up, are still to be understood. While capillaries usually studied are microscopic pore networks etched in different materials, our concern is in macroscopic single capillaries made of glass. With a length of several centimeters and a diameter of a few micrometers at the exit, these capillaries have nevertheless the same aspect ratio as the etched pores (length/diameter ≈ 100). One of the leading goals of this research on single capillaries is to produce multi-charged ion beams with diameters smaller than a micrometer (nano-beams). These glass capillaries offer the opportunity to be used as an ion funnel due to their amazing properties of guiding and focusing highly charged ion beams without altering neither their initial charge state nor the beam emittance (

The transmission of a laser beam through a tapered glass capillary was investigated both experimentally and theoretically for light microbeams. The transmittances of laser light at 488 and 633 nm through capillaries were measured to be up to 15%, depending on the outlet diameter. By characterizing a real capillary with precise measurement of the whole capillary geometry, a realistic simulation allowed us to calculate the transmittance. By using a Gaussian profile as the input beam in a simulation, the calculated transmittances well reproduced the experimental ones. The density enhancement of the extracted beam was derived and discussed.

We measured the residual μ+ polarizations in various liquid scintillators to search for an ideal material for an active muon stopper in which the muon spin polarization can be preserved and at the same time their energy loss and tracks can be measured by scintillation lights from the stopper material. We found the residual polarizations of mineral‐oil base liquid scintillators were \sim 4 times larger than that of a plastic scintillator. Further increase of the residual polarization was observed with a mixture of CCl4.

A new electromagnetic calorimeter is designed for the experiment E246 at KEK. It consists of 768 CsI(Tl) crystals with PIN-diode readout. A short description of the calorimeter design and performance is given.

An energy-dispersive detector of extreme ultraviolet (EUV) photons that uses superconducting tunnel junctions (STJs) is being developed. The performance of the STJs for detecting EUV photons was evaluated at a synchrotron radiation facility. An energy resolution of 17.8±0.6 eV in FWHM (including external noise of 17.6±0.2 eV) for 55 eV EUV photons was obtained with a 100×100 μm2 STJ.

Towards production of microbeams, propagation of laser beams of visible light with wavelengths of 488, 633 and 670 nm through tapered glass capillaries has been studied. In conjunction with an optical lens upstream of the capillaries with outlet sizes ranging from 17 to 100 μm, transmission efficiency more than 80% has been achieved for outlet diameters more than 40 μm

The π0 detector constructed for the T-violation search experiment E246 at KEK is described. It consists of 768 CsI(Tl) crystals with PIN photodiode readout. The crystals are assembled in a tight barrel with holes for muons entering the magnetic spectrometer. The design and performance of the calorimeter are presented. The average light yield of 11 000 p.e./MeV and average equivalent noise level of 63 keV (bench test) were obtained for the CsI(Tl) modules used in the calorimeter. The coherent noise was found to be about 11 keV per a module. A readout electronics has been specifically developed for the high counting rate environment of the experiment. A π0 invariant mass resolution of 9.9 MeV (σ) was obtained for the whole detector, including regions around the muon holes. A time resolution of 3.8 ns (rms) was achieved in the photon energy range of 10–200 MeV.

Microbeams of MeV ions focused through tapered glass capillaries with end-windows have been used for the irradiation of small volume (order of 1μm) inside living cells cultivated in liquid medium. In order to control the dose with accuracy of about 1 MeV, single ion irradiation and its counting method are required. We propose here the possibility of single ion counting by using glass capillaries with plastic scintillator end-windows.

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 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...

Two years ago, a prototype of a highly sensitive beam current monitor with a high-temperature superconducting (HTS) SQUID, an HTS current sensor and an HTS magnetic shield, that is, an HTS-SQUID monitor, was installed in the beam transport line of the RIKEN ring cyclotron (RRC). As a result, the beam intensity of a sub-μA beam was successfully measured by the prototype HTS-SQUID monitor. In fact, the intensity of a sub-μA 40Ar15+ (63 MeV/u) beam was successfully measured with a 500 nA resolution. However, the current resolution of the prototype HTS-SQUID monitor is not sufficient to measure the current of a uranium beam, which is accelerated in a new radioactive isotope (RI) beam facility called "RI Beam Factory" (RIBF). A minimum current resolution of 1 nA is required for the measurement of the uranium beam. Therefore, we are developing a new HTS-SQUID monitor so as to improve the current resolution. This new monitor consists of three parts, the HTS SQUID, an HTS current sensor and an HTS magnetic shield, and these parts have been separately developed this year. The high-permeability core that is installed in the two input coils of the HTS-SQUID is an extremely important part in this new HTS-SQUID monitor. A 50-fold improvement in gain was successfully realized using the high-permeability core compared with that obtained without the high-permeability core. Another key factor is the substrate of the HTS current sensor. A MgO ceramic tube was used for the substrate of the HTS current sensor in the prototype HTS-SQUID monitor. However, it was difficult to form the bridge circuit using the MgO ceramic substrate in the new HTS-SQUID monitor, because the bridge circuit that magnetically connects the HTS current sensor and the HTS-SQUID has to be three-dimensional. To solve this problem, silver (Ag) of 99.9% purity was adopted for the substrates of the HTS current sensor in the new HTS-SQUID monitor. Then the surfaces of the substrates were coated by a thin layer (70μm) of Bi2-Sr2-Ca1-Cu2-Ox (Bi 2212), which is an HTS material. We report the results of this development.

We have developed methods to focus slow highly charged ions, MeV ions, and muon beams with various glass-made beam optics. (1) A focusing effect for an Ar8 + beam of 8 keV through a cm-long tapered capillary was obtained with a density enhancement of the transmitted beam compared with that of the input beam, which increases from 1 to 6 as the input current decreases from 30 pA to 0.8 pA. To study the stability of the transmitted beams through a glass capillary, we have measured the transmission of an 104 keV Ar8+ beam through a gap between a pair of parallel glass plates, and observed a precisely vibrational output current. (2) For 4 MeV He2+ beam, a 100 times density enhanced beam by a cm-long tapered capillary with a closed outlet was utilized to irradiate a cell in liquid. The range of the beam was controlled by the closed outlet with accuracy of ~1 μm. (3) Using 40 cm-long tapered glass tubes, a density enhancement of a factor of 2 was observed for both positive and negative muon beams with an energy of 13 MeV.

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.

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.

Niobium-based superconducting tunnel junctions (STJs) with aluminum trapping layers as X-ray detectors were fabricated. We applied a fabrication technique for reducing the leakage current and improving the energy resolution for X-rays at around 6 keV. The edges of two Al layers sandwiching a tunneling barrier were oxidized by plasma discharge. The performance of these new STJs was compared with other types of STJs to which thermal oxidization in an O2 atmosphere had been applied. The oxidization process in O2 plasma significantly improved the energy resolution for X-rays, which reached values (FWHM) of 41 eV, 58 eV, 65 eV, and 129 eV for STJs with the size of 20×20 µm2, 100×100 µm2, 200×200 µm2, and 500×500 µm2, respectively.

The spectra of substrate phonon events induced by illuminating with X-rays obtained with Nb-based superconducting tunnel junctions (STJs) fabricated on a sapphire substrate were examined. We constructed a geometrical model in which the collection efficiency of phonons is proportional to the solid angle subtended to the STJ from the position of the absorption. By using the Monte-Carlo simulation, we succeeded in fairly reproducing the features of the spectra obtained by our measurements. A comparison of the model spectra with the measured ones revealed that a mismatch of the acoustic impedance at the junction-substrate interface and the spatial spread of a phonon cloud play an important role in the determination of the spectra. By including these effects, we show that the measured spectra can be well reproduced by adjusting only one free parameter, the radius of the phonon cloud. We estimated this radius in a sapphire substrate to be ∼20 µm under 5.9 keV X-ray illumination.