Novel Approaches for Intensifying Negative C60 Ion Beams Using Conventional Ion Sources Installed on a Tandem Accelerator

Chiba, Ayano; Usui, Aya; Hirano, Yoshimi; Yamada, K.; Narumi, K.; Saitoh, Yoichi

doi:10.3390/qubs4010013

Cited by 9 publications

(4 citation statements)

References 26 publications

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“…Irradiation of diamond samples with C 60 ions was conducted at the Takasaki Institute for Advanced Quantum Science, of the National Institutes for Quantum Science and Technology (QST), using a 3 MV tandem accelerator and a newly developed high-flux C 60 negative ion source 37 . Powder of C 60 with a purity of 99.5% was used.…”

Section: Methodsmentioning

confidence: 99%

Latent ion tracks were finally observed in diamond

Amekura,

Chettah,

Narumi

et al. 2024

Nat Commun

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Injecting high-energy heavy ions in the electronic stopping regime into solids can create cylindrical damage zones called latent ion tracks. Although these tracks form in many materials, none have ever been observed in diamond, even when irradiated with high-energy GeV uranium ions. Here we report the first observation of ion track formation in diamond irradiated with 2–9 MeV C60 fullerene ions. Depending on the ion energy, the mean track length (diameter) changed from 17 (3.2) nm to 52 (7.1) nm. High resolution scanning transmission electron microscopy (HR-STEM) indicated the amorphization in the tracks, in which π-bonding signal from graphite was detected by the electron energy loss spectroscopy (EELS). Since the melting transition is not induced in diamond at atmospheric pressure, conventional inelastic thermal spike calculations cannot be applied. Two-temperature molecular dynamics simulations succeeded in the reproduction of both the track formation under MeV C60 irradiations and the no-track formation under GeV monoatomic ion irradiations.

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Section: Methodsmentioning

confidence: 99%

Latent ion tracks were finally observed in diamond

Amekura,

Chettah,

Narumi

et al. 2024

Nat Commun

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“…Irradiation of C 60 ions was conducted at the Takasaki Advanced Radiation Research Institute (TARRI), of the National Institutes for Quantum Science and Technology (QST), using a 3 MV tandem accelerator and a newly developed high-flux C 60 negative ion source [25]. C 60 ions with charge state of +1 (C 60 + ) were utilized for 1-6 MeV irradiations, while those with +2 (C 60 2+ ) were utilized for 9 MeV irradiation.…”

Section: Methodsmentioning

confidence: 99%

“…The samples were mostly irradiated to low fluences of 5 × 10 10 -1 × 10 11 C 60 cm −2 to avoid overlaps between the tracks. For precise control of the low fluence, the ion flux was reduced to below 50 pA through mesh-type attenuators and an aperture of 3 mm in diameter, while using the high-flux ion source [25]. The incident angle was set to 7°from the surface normal to avoid channeling effects.…”

Section: Methodsmentioning

confidence: 99%

Mechanism of ion track formation in silicon by much lower energy deposition than the formation threshold

Amekura

Narumi²,

Chiba³

et al. 2023

Phys. Scr.

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Mechanism of the ion track formation in crystalline silicon (c-Si) is discussed, particularly under 1–9 MeV C60 ion irradiation. In this energy region, the track formation was not expected because the energy E was much lower than the threshold of E th = 17 MeV determined by extrapolation from higher energy data in the past literature. The track formation is different between irradiations of C60 ions and of monoatomic ions: The tracks were observed under 3 MeV C60 ion irradiation but not under 200 MeV Xe ions, while both the irradiations have the same electronic stopping (S e) of 14 keV nm−1 but much higher nuclear stopping (S n) for the former ions. The involvement of S n is suggested for the C60 ions. While the inelastic thermal spike (i-TS) calculations predict that the high energy monoatomic ion irradiation forms the tracks, the tracks have never been experimentally detected, suggesting quick annihilation of the tracks by highly enhanced recrystallization in c-Si. Exceptions are C60 ions of 1–9 MeV, where the track radii are well reproduced by the i-TS theory with assuming the melting transition. Collisional damage induced by the high S n from C60 ions obstructs the recrystallization in c-Si. Then the tracks formed by the melting transition survive against the recrystallization. This is a new type of the synergy effect between S e and S n, different from the already-known mechanisms, i.e., the pre-damage effect and the unified thermal spike. While c-Si was believed as a radiation-hard material in the S e regime with high S e threshold, this study suggests that c-Si has a low S e threshold but with efficient recrystallization.

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“…(4) Regarding novel application of quantum beam technology, this Special Issue provides the recent progress of phase imaging using synchrotron X-rays and pulsed neutron beams [11] and ultrafast electron diffractometers with relativistic electron pulses for the investigation of ultrafast structural dynamics [12]. Furthermore, as for new ion beam applications, highly intensified C 60 ion beams created by negatively charged fullerene with the electron attachment technique [13] and widely applied microbeams, being utilized for the samples under atmospheric conditions via tapered glass capillary attached directly to beam lines [14], are reported.…”

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confidence: 99%