Fluence enhancement of a 4 MeV‐C4+ ion beam transmitted through a cylindrical glass channel after charging

一対の凸面と凹面で構成される円筒形ガラスチャネル(CGC)を通過するイオンビームによって誘起される表面の帯電がイオンの運動に与える効果について研究を行った。実験では、4MeV C4+イオンビームがCGCを通過する際、その前後でのイオン数をCR-39固体核飛跡検出器で、またイオンのエネルギーをシリコン半導体検出器で測定した。その結果、CGCを通過してもイオンのエネルギーは変化せず、表面の帯電後のフルエンス比（出射イオンビーム/入射イオンビーム）が増加することがわかった。 さらに、イオン通過の幾何学的限界を超えた1.5°のＣＧＣの傾斜角に対して、帯電後に凹面近くを通過するイオンのフルエンス比は1を超えることも確認した。これらより、今回用いたCGCはイオンのエネルギーを変えることなく、イオンビームを偏向や集束できることがわかった

Uniformization of the transverse beam profile by means of nonlinear focusing method

It has been known that uniformization of a beam with a Gaussian profile is possible utilizing odd-order nonlinear focusing in the beam transport system, and this has recently been employed for uniform beam irradiation. Here, we have theoretically studied uniformization of the transverse beam profile using nonlinear-focusing forces produced by multipole magnets in detail. In the case where the nonlinear field of the multipole magnet is given by an infinite power series, all the odd-order multipole strengths required for uniformization of a Gaussian beam and the extent of the resultant uniform region have been expressed using the Twiss parameters. We have shown the principle of uniformization using even-order nonlinear fields. We have also actually demonstrated the transformation of a beam with an asymmetric distribution into one with a uniform distribution by utilizing nonlinear focusing, especially with the sextupole and octupole fields. The validity of the formulas presented here was confirmed through particle-tracking simulations. A practical method to realize a uniform profile using beam collimation and octupole focusing is also presented

An irradiation device for biological targets using focused microbeams of cyclotron-accelerated heavy ions

For use in medical and life science research, a device and sample preparation methods were developed to irradiate cultured cells and individual animals with a focused microbeam of cyclotron-accelerated heavy-ions. The new irradiation device positions both sample and microscope with micrometer precision. The beam size is smaller than 3 μm when the distance between the beam exit from vacuum to the irradiation device is less than 500 μm for 13.0 MeV/n 20Ne ions. This beam size is sufficiently small to irradiate intracellular targets in cultured cells. A beam size smaller than 10 μm was obtained for 12C ions of 26.7 MeV/n at a distance of 2 mm from the beam exit, which enabled irradiation of specific cells in a small model animal. Methods to prepare cultured cells and the nematode Caenorhabditis elegans for irradiation using the new device are reported, and the results of the first irradiation experiments presented

Evaluation of the Cooling Effect by He Gas for the Production of At-211 with a Bi plate

Astatine-211 is one of the promising alpha-emitting radionuclides for the targeted alpha therapy (TAT), internal radiotherapy using alpha-emitting radioisotopes. At-211 is basically produced by irradiating He beams with 28–29 MeV to a bismuth (Bi) target. Irradiations with high beam current (µA order) are necessary to produce At-211 for preclinical and clinical studies because they require its radioactivity on the order of subGBq to GBq. Low melting point of Bi (273.1°C) often causes melting of the Bi during irradiation with high beam current. The aim of this study is therefore to optimize irradiation condition without observing Bi melting

Identification of mitochondrial DNA polymorphisms that alter mitochondrial matrix pH and intracellular calcium dynamics.

Mitochondrial DNA (mtDNA) is highly polymorphic, and its variations in humans may contribute to individual differences in function as well as susceptibility to various diseases such as Parkinson disease, Alzheimer disease, bipolar disorder, and cancer. However, it is unclear whether and how mtDNA polymorphisms affect intracellular function, such as calcium signaling or pH regulation. Here we searched for mtDNA polymorphisms that have intracellular functional significance using transmitochondrial hybrid cells (cybrids) carrying ratiometric Pericam (RP), a fluorescent calcium indicator, targeted to the mitochondria and nucleus. By analyzing the entire mtDNA sequence in 35 cybrid lines, we found that two closely linked nonsynonymous polymorphisms, 8701A and 10398A, increased the basal fluorescence ratio of mitochondria-targeted RP. Mitochondrial matrix pH was lower in the cybrids with 8701A/10398A than it was in those with 8701G/10398G, suggesting that the difference observed by RP was mainly caused by alterations in mitochondrial calcium levels. Cytosolic calcium response to histamine also tended to be higher in the cybrids with 8701A/10398A. It has previously been reported that 10398A is associated with an increased risk of Parkinson disease, Alzheimer disease, bipolar disorder, and cancer, whereas 10398G associates with longevity. Our findings suggest that these mtDNA polymorphisms may play a role in the pathophysiology of these complex diseases by affecting mitochondrial matrix pH and intracellular calcium dynamics

Characteristics of focusing high-energy heavy ion microbeam system at the JAEA AVF cyclotron

Ion optical analysis was made for a new focusing high-energy heavy ion microbeam system connected to the AVF cyclotron (K=110) at the accelerator facility, TIARA of JAEA Takasaki. The focusing performance of the microbeam system was estimated from both the calculation up to third-order term using TRANSPORT code and the measurement of beam resolution with the secondary electron imaging. As a result, a minimum beam size was evaluated at 0.56 um and 0.62 um in FWHM for the X and Y directions, respectively. The high-energy heavy ion microbeam system seemed to have been established as designed by the calculation with the TRANSPORT code, because it was confirmed that the calculation results was fairly reproduced by the measurement result