The crystallization of ion beams has recently been established in the rf quadrupole storage ring PALLAS (PAul Laser CooLing Acceleration System) for laser-cooled 24 Mg + ion beams at an energy of about 1 eV. Yet, unexpectedly sharp constraints had to be met concerning the confinement strength and the longitudinal laser cooling rate. In this paper, related and up to now unseen heating mechanisms are pinpointed for crystalline beams. The weak but inevitable diffusive transverse heating associated with the laser cooling process itself is investigated, possibly allowing the future measurement of the latent heat of the ion crystal. As a function of the beam velocity, the influence of bending shear on the attainability of larger crystalline structures is presented. Finally, rf heating of crystalline beams of different structure is studied for discontinuous cooling.The crystallization of ion beams has recently been established in the rf quadrupole storage ring PALLAS (PAul Laser CooLing Acceleration System) for laser-cooled 24 Mg + ion beams at an energy of about 1 eV. Yet, unexpectedly sharp constraints had to be met concerning the confinement strength and the longitudinal laser cooling rate. In this paper, related and up to now unseen heating mechanisms are pinpointed for crystalline beams. The weak but inevitable diffusive transverse heating associated with the laser cooling process itself is investigated, possibly allowing the future measurement of the latent heat of the ion crystal. As a function of the beam velocity, the influence of bending shear on the attainability of larger crystalline structures is presented. Finally, rf heating of crystalline beams of different structure is studied for discontinuous cooling.

Journal of Physics B Atomic Molecular and Optical PhysicsJan 23, 200323 citations

Ion machine-gun experiment at Hiroshima University

室尾　健人, Seiichi Ito, 岡本宏己 +3 more

Ion beams with micrometer-order spot size, so-called “microbeams,” have been utilized in a variety of fields. These include the biological response of radiation in cells and the single event effects of a semiconductor, etc. On the other hand, certain applications, such as the creation of a color center in a diamond, require an ion beam with not only the higher precision of a nanometer-order diameter but also the ability to implant ions one by one. The ion machine gun (IMG) is the possible choice for the realization of this distinctive ion beam. It is mainly composed of a linear Paul trap (LPT) and Doppler-cooling lasers. Ions laser-cooled to nearly absolute zero in the LPT reach a “Coulomb crystalline state.” If we extract ions in this state without heating, a unique ion beam can be attained. Most ion species, even if they cannot be directly laser-cooled, can be cooled sympathetically and crystallized through Coulomb collisions with laser-cooled ions simultaneously confined in the LPT. At Hiroshima University, we conduct proof-of-principle experiments of the IMG using laser-cooled calcium ions and sympathetically cooled nitrogen ions. Here we discuss the fundamental principle and experimental results of this study.Ion beams with micrometer-order spot size, so-called “microbeams,” have been utilized in a variety of fields. These include the biological response of radiation in cells and the single event effects of a semiconductor, etc. On the other hand, certain applications, such as the creation of a color center in a diamond, require an ion beam with not only the higher precision of a nanometer-order diameter but also the ability to implant ions one by one. The ion machine gun (IMG) is the possible choice for the realization of this distinctive ion beam. It is mainly composed of a linear Paul trap (LPT) and Doppler-cooling lasers. Ions laser-cooled to nearly absolute zero in the LPT reach a “Coulomb crystalline state.” If we extract ions in this state without heating, a unique ion beam can be attained. Most ion species, even if they cannot be directly laser-cooled, can be cooled sympathetically and crystallized through Coulomb collisions with laser-cooled ions simultaneously confined in the LPT. At Hiroshima University, we conduct proof-of-principle experiments of the IMG using laser-cooled calcium ions and sympathetically cooled nitrogen ions. Here we discuss the fundamental principle and experimental results of this study.

May 1, 20260 citations

Phase Transitions of Stored Laser-Cooled Ions

HERBERT WALTHER

Advances in atomic, molecular, and optical physicsJan 1, 1993167 citations

Phase Transitions of Stored Laser-Cooled Ions: A First Step Towards Crystallization in Storage Rings

R. Blümel, E. Peik, W. Quint +1 more

Springer proceedings in physicsJan 1, 19890 citations

Doppler-cooled ions in a compact reconfigurable Penning trap

Brian J. McMahon, Curtis Volin, Wade G. Rellergert +1 more

We report the design and experimental demonstration of a compact, reconfigurable Penning ion trap constructed with rare-earth permanent magnets placed outside of a trap vacuum enclosure. We describe the observation of Doppler laser cooling of ions in a permanent magnet Penning trap. We detail a method for quantifying and optimizing the trap magnetic-field uniformity in situ using a thermal beam of neutral $^{40}\mathrm{Ca}$ precursor atoms. Doppler laser cooling of $^{40}\mathrm{Ca}^{+}$ is carried out at 0.65 T, and side-view images of trapped ion fluorescence show crystalline order for both two- and three-dimensional arrays. Measured $^{40}\mathrm{Ca}^{+}$ trap frequencies confirm the magnetic-field characterization with neutral $^{40}\mathrm{Ca}$ . The compact trap described here enables a variety of cold ion experiments with low size, weight, power, and cost requirements relative to traditional electromagnet-based Penning traps.We report the design and experimental demonstration of a compact, reconfigurable Penning ion trap constructed with rare-earth permanent magnets placed outside of a trap vacuum enclosure. We describe the observation of Doppler laser cooling of ions in a permanent magnet Penning trap. We detail a method for quantifying and optimizing the trap magnetic-field uniformity in situ using a thermal beam of neutral $^{40}\mathrm{Ca}$ precursor atoms. Doppler laser cooling of $^{40}\mathrm{Ca}^{+}$ is carried out at 0.65 T, and side-view images of trapped ion fluorescence show crystalline order for both two- and three-dimensional arrays. Measured $^{40}\mathrm{Ca}^{+}$ trap frequencies confirm the magnetic-field characterization with neutral $^{40}\mathrm{Ca}$. The compact trap described here enables a variety of cold ion experiments with low size, weight, power, and cost requirements relative to traditional electromagnet-based Penning traps.

arXiv:1909.02034Physical Review AJan 8, 202014 citations

^{40}\mathrm{Ca}

precursor atoms. Doppler laser cooling of

^{40}\mathrm{Ca}^{+}

is carried out at 0.65 T, and side-view images of trapped ion fluorescence show crystalline order for both two- and three-dimensional arrays. Measured

^{40}\mathrm{Ca}^{+}

trap frequencies confirm the magnetic-field characterization with neutral

^{40}\mathrm{Ca}

. The compact trap described here enables a variety of cold ion experiments with low size, weight, power, and cost requirements relative to traditional electromagnet-based Penning traps.