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Journal Articles

Nonresonant $$p$$-wave direct capture and interference effect observed in the $$^{16}$$O$$(n,gamma)^{17}$$O reaction

Nagai, Yasuki*; Kinoshita, Mitsutaka*; Igashira, Masayuki*; Nobuhara, Yuriko*; Makii, Hiroyuki; Mishima, Kenji*; Shima, Tatsushi*; Mengoni, A.*

Physical Review C, 102(4), p.044616_1 - 044616_8, 2020/10

 Times Cited Count:0

Journal Articles

Anomalous radioisotope production for $$^{68}$$ZnO using polyethylene by accelerator neutrons

Tsukada, Kazuaki; Nagai, Yasuki*; Hashimoto, Shintaro; Minato, Futoshi; Kawabata, Masako*; Hatsukawa, Yuichi*; Hashimoto, Kazuyuki*; Watanabe, Satoshi*; Saeki, Hideya*; Motoishi, Shoji*

Journal of the Physical Society of Japan, 89(3), p.034201_1 - 034201_7, 2020/03

 Times Cited Count:0 Percentile:100(Physics, Multidisciplinary)

We found anomalously large yields of $$^{67}$$Ga, $$^{66}$$Ga, $$^{rm 69m}$$Zn and $$^{64}$$Cu by neutron irradiation on a $$^{68}$$ZnO sample in a polyethylene shield. Neutron beams are generated from the $$^{9}$$Be($$d,n$$) reaction for 50 MeV deuterons. The yields obtained were more than 20 times larger than those in the unshielded sample. On the other hand, the yields of $$^{67}$$Ga, $$^{66}$$Ga, $$^{rm 69m}$$Zn and $$^{64}$$Cu from a metallic $$^{68}$$Zn sample and the yields of $$^{67}$$Cu, $$^{65}$$Ni and $$^{65}$$Zn from the $$^{68}$$ZnO and $$^{68}$$Zn samples were almost insensitive to the shield conditions. This finding would provide us a unique capability of accelerator neutrons to simultaneously produce a large amount of several radioisotopes, including proton induced reaction products, by using a single sample. The experimental data were compared with the yields estimated by using the Particle and Heavy Ion Transport code System and the result was discussed.

Journal Articles

$$^{99}$$Mo yield using large sample mass of MoO$$_{3}$$ for sustainable production of $$^{99}$$Mo

Tsukada, Kazuaki; Nagai, Yasuki*; Hashimoto, Kazuyuki*; Kawabata, Masako*; Minato, Futoshi; Saeki, Hideya*; Motoishi, Shoji*; Ito, Masatoshi*

Journal of the Physical Society of Japan, 87(4), p.043201_1 - 043201_5, 2018/04

 Times Cited Count:5 Percentile:35.7(Physics, Multidisciplinary)

Journal Articles

Measurement and estimation of the $$^{99}$$Mo production yield by $$^{100}$$Mo($$n,2n$$)$$^{99}$$Mo

Minato, Futoshi; Tsukada, Kazuaki*; Sato, Nozomi*; Watanabe, Satoshi*; Saeki, Hideya*; Kawabata, Masako*; Hashimoto, Shintaro; Nagai, Yasuki*

Journal of the Physical Society of Japan, 86(11), p.114803_1 - 114803_6, 2017/11

 Times Cited Count:5 Percentile:42.65(Physics, Multidisciplinary)

We have measured the yield of $$^{99}$$Mo, the mother nuclide of $$^{99m}$$Tc used in nuclear diagnostic procedure. $$^{99}$$Mo was produced by $$^{100}$$Mo($$n$$,$$2n$$)$$^{99}$$Mo using neutrons with thermal energy up to about 40 MeV, provided by C($$d$$,$$n$$). The $$^{99}$$Mo yield agrees with an estimated yield with the use of the latest data of C($$d$$,$$n$$) and the evaluated cross section given in the JENDL. Based on this, a new calculation was carried out to produce $$^{99}$$Mo to seek for a good economical condition. Various conditions such as the $$^{100}$$MoO$$_{3}$$ sample mass, the distance between the carbon target and the sample, the radius of the deuteron beam, and the neutron irradiation time were considered. The calculated $$^{99}$$Mo yield indicates that about 30% of the $$^{99}$$Mo demand in Japan can be fulfilled with a single accelerator. The elusion of $$^{99m}$$Tc from the $$^{99}$$Mo twice per day would meet about 50% of the $$^{99}$$Mo demand.

Journal Articles

Application of $$^{67}$$Cu produced by $$^{68}$$Zn($$n,n'p+d$$)$$^{67}$$Cu to biodistribution study in tumor-bearing mice

Sugo, Yumi*; Hashimoto, Kazuyuki*; Kawabata, Masako*; Saeki, Hideya*; Sato, Shunichi*; Tsukada, Kazuaki; Nagai, Yasuki*

Journal of the Physical Society of Japan, 86(2), p.023201_1 - 023201_3, 2017/02

 Times Cited Count:10 Percentile:24.69(Physics, Multidisciplinary)

$$^{67}$$Cu produced by the $$^{68}$$Zn($$n,n'p+d$$)$$^{67}$$Cu reaction was used for the first time to determine the biodistribution of $$^{67}$$CuCl$$_{2}$$ in colorectal tumor-bearing mice. High uptake of $$^{67}$$Cu was observed in the tumor as well as in the liver and kidney which are the major organs for copper metabolism. The result showing $$^{67}$$Cu accumulation in the tumor suggests that $$^{67}$$CuCl$$_{2}$$ can be a potential radionuclide agent for cancer radiotherapy. It would also encourage further studies on the therapeutic effect in small animals using an increased dose of $$^{67}$$Cu produced by the $$^{68}$$Zn($$n,n'p+d$$)$$^{67}$$Cu reaction using intense neutrons available at present.

Journal Articles

SPECT imaging of mice with $$^{99m}$$Tc-radiopharmaceuticals obtained from $$^{99}$$Mo produced by $$^{100}$$Mo(n,2n)$$^{99}$$Mo and fission of $$^{235}$$U

Hashimoto, Kazuyuki; Nagai, Yasuki; Kawabata, Masako; Sato, Nozomi*; Hatsukawa, Yuichi; Saeki, Hideya; Motoishi, Shoji*; Ota, Masayuki; Konno, Chikara; Ochiai, Kentaro; et al.

Journal of the Physical Society of Japan, 84(4), p.043202_1 - 043202_4, 2015/04

 Times Cited Count:5 Percentile:50.64(Physics, Multidisciplinary)

Journal Articles

Production of $$^{rm 95m}$$Tc for Compton camera imaging

Hatsukawa, Yuichi; Hashimoto, Kazuyuki; Tsukada, Kazuaki; Sato, Tetsuya; Asai, Masato; Toyoshima, Atsushi; Nagai, Yasuki; Tanimori, Toru*; Sonoda, Shinya*; Kabuki, Shigeto*; et al.

Journal of Radioanalytical and Nuclear Chemistry, 303(2), p.1283 - 1285, 2015/02

 Times Cited Count:2 Percentile:74.39(Chemistry, Analytical)

Technetium-99m ($$^{rm 99m}$$Tc) is used in radioactive medical diagonostic tests, for example as a radioactive tracer that medical equipment can detect in the human body. It is well suited to the role because it emits readily detectable 141 keV $$gamma$$ rays, and its half-life is 6.01 hours (meaning that about 94% of it decays to technetium-99 in 24 hours). There are at least 31 commonly used radiopharmaceuticals based on technetium-99m for imaging and functional studies of the brain, myocardium, thyroid, lungs, liver, gallbladder, kidneys, skeleton, blood, and tumors. Recent years, with the develop-ment of the Compton camera which can realize high position resolution, technetium isotopes emitting high energy $$gamma$$-rays are required. In this study, technetium-95m which emits some $$gamma$$ rays around 800 keV was produced by the $$^{95}$$Mo(p,n)$$^{rm 95m}$$Tc reaction.

Journal Articles

New phenomenon observed in thermal release of $$^{99m}$$Tc from molten $$^{100}$$MoO$$_{3}$$

Kawabata, Masako; Nagai, Yasuki; Hashimoto, Kazuyuki; Saeki, Hideya; Motoishi, Shoji*; Sato, Nozomi*; Ota, Akio*; Shiina, Takayuki*; Kawauchi, Yukimasa*

Journal of the Physical Society of Japan, 84(2), p.023201_1 - 023201_4, 2015/02

 Times Cited Count:6 Percentile:45.67(Physics, Multidisciplinary)

$$^{99m}$$Tc for medical use can be separated by thermochromatography from a molten $$^{99}$$MoO$$_{3}$$ sample. Effect of moist oxygen gas on the $$^{99m}$$Tc release from molten $$^{99}$$MoO$$_{3}$$ samples was investigated using a $$^{99}$$Mo/$$^{99m}$$Tc generator. $$^{99}$$Mo was produced with $$^{100}$$Mo(n,2n)$$^{99}$$Mo. A new phenomenon has been observed: release rate, separation- and recovery-efficiencies of $$^{99m}$$Tc were higher in the moist oxygen gas than those in the dry oxygen gas. The present result is a significant progress towards the stable production of a high quality $$^{99m}$$Tc from a molten MoO$$_{3}$$ sample with high separation efficiency. The result would also give us a new insight into the interaction between the moist oxygen gas and the molten MoO$$_{3}$$.

Journal Articles

First measurement of the radionuclide purity of the therapeutic isotope $$^{67}$$Cu produced by $$^{68}$$Z($$n$$,$$x$$) reaction using $$^{rm nat}$$C($$d$$,$$n$$) neutrons

Sato, Nozomi; Tsukada, Kazuaki; Watanabe, Satoshi; Ishioka, Noriko; Kawabata, Masako; Saeki, Hideya; Nagai, Yasuki; Kin, Tadahiro*; Minato, Futoshi; Iwamoto, Nobuyuki; et al.

Journal of the Physical Society of Japan, 83(7), p.073201_1 - 073201_4, 2014/07

 Times Cited Count:10 Percentile:35.24(Physics, Multidisciplinary)

We have for the first time demonstrated that the therapeutic nuclide of $$^{67}$$Cu produced by $$^{68}$$Zn($$n$$,$$x$$)$$^{67}$$Cu has highest radionuclide purity compared to previous ones. We measured a $$gamma$$-ray spectrum of the reaction product produced by bombarding an enriched $$^{68}$$Zn sample with neutrons with a HPGe detector. The neutrons were obtained by $$^{rm nat}$$C($$d$$,$$n$$) using 41 MeV deuterons provided from Takasaki Ion Accelerators for Advanced Radiation Application of Japan Atomic Energy Agency. Relative production yields of impurity radionuclides such as $$^{65}$$Zn to $$^{67}$$Cu are extremely low, which allow us to chemically separate $$^{67}$$Cu from an irradiated $$^{68}$$Zn sample with a few steps and to reuse high cost an enriched $$^{68}$$Zn sample. The present result strongly suggest that the $$^{68}$$Zn($$n$$,$$x$$)$$^{67}$$Cu reaction is the most promising route to produce high quality $$^{67}$$Cu and could solve a longstanding problem of establishing an appropriate production method of $$^{67}$$Cu.

Journal Articles

High thermo-separation efficiency of $$^{99m}$$Tc from molten $$^{100}$$MoO$$_{3}$$ samples by repeated milking tests

Nagai, Yasuki; Kawabata, Masako; Sato, Nozomi; Hashimoto, Kazuyuki; Saeki, Hideya; Motoishi, Shoji*

Journal of the Physical Society of Japan, 83(8), p.083201_1 - 083201_4, 2014/07

 Times Cited Count:9 Percentile:37.67(Physics, Multidisciplinary)

Journal Articles

Generation of medical radioisotopes using accelerator neutrons

Nagai, Yasuki; Hashimoto, Kazuyuki

Nippon Butsuri Gakkai-Shi, 69(6), p.370 - 375, 2014/06

In Japan, about 0.9 million diagnostic procedures are carried out using $$^{rm 99m}$$Tc, the daughter nuclide of $$^{99}$$Mo with a half-life of 66 h, separated from $$^{99}$$Mo; all $$^{99}$$Mo radioisotopes are imported. Most of $$^{99}$$Mo has been produced by the fission reaction of highly enriched $$^{235}$$U in research reactors in the world. However, a number of incidents of the reactors caused the shortage of $$^{99}$$Mo worldwide, which triggered widespread discussions on the reliable supply of $$^{99}$$Mo. We proposed a new route to produce a large quantity of high quality $$^{99}$$Mo using fast neutrons from an accelerator.

Journal Articles

Measurements of neutron capture cross section for $$^{207,208}$$Pb

Segawa, Mariko; Toh, Yosuke; Harada, Hideo; Kitatani, Fumito; Koizumi, Mitsuo; Fukahori, Tokio; Oshima, Masumi*; Iwamoto, Nobuyuki; Iwamoto, Osamu; Hatsukawa, Yuichi; et al.

AIP Conference Proceedings 1594, p.339 - 344, 2014/05

 Times Cited Count:0 Percentile:100

Journal Articles

Radionuclide production

Hashimoto, Kazuyuki; Nagai, Yasuki

Comprehensive Biomedical Physics, Vol.8, p.219 - 227, 2014/00

Radionuclides for medical use are produced in nuclear reactors and in accelerators. The thermal neutron fluxes in nuclear reactors are several orders of magnitude higher than those of other neutron sources, such as accelerator neutrons. Hence, nuclear reactors have been playing important roles in the production of large quantity of medical radionuclides with their half-lives longer than several days. In accelerators, medical radionuclides with their half-lives longer than several minutes are produced. Recent progresses in accelerator technology as well as targetry technology, however, could enable one to obtain high-flux bremsstrahlung and intense energetic accelerator neutrons, and thereby to study new routes to produce medical radionuclides.

Journal Articles

New challenges to medical and industrial applications using accelerators

Nagai, Yasuki

Hoshasen, 39(2), P. 43, 2013/11

When I was carrying out a basic study of nucleus physics using an accelerator, I was impressed with the ability of the accelerator. I thought that accelerators could contribute innovative works in many industry fields. In the practical application of accelerators in the medicine and industry, one has to find an important and interesting subject to be worth challenge on the basis of one's own knowledge and experience. Here, I would like to report my experience of the medicine and industrial use of accelerators.

Journal Articles

Generation of radioisotopes with accelerator neutrons by deuterons

Nagai, Yasuki; Hashimoto, Kazuyuki; Hatsukawa, Yuichi; Saeki, Hideya; Motoishi, Shoji; Sonoda, Nozomi; Kawabata, Masako; Harada, Hideo; Kin, Tadahiro*; Tsukada, Kazuaki; et al.

Journal of the Physical Society of Japan, 82(6), p.064201_1 - 064201_7, 2013/06

 Times Cited Count:32 Percentile:14.72(Physics, Multidisciplinary)

Journal Articles

New production routes for medical isotopes $$^{64}$$Cu and $$^{67}$$Cu using accelerator neutrons

Kin, Tadahiro*; Nagai, Yasuki; Iwamoto, Nobuyuki; Minato, Futoshi; Iwamoto, Osamu; Hatsukawa, Yuichi; Segawa, Mariko; Harada, Hideo; Konno, Chikara; Ochiai, Kentaro; et al.

Journal of the Physical Society of Japan, 82(3), p.034201_1 - 034201_8, 2013/03

 Times Cited Count:28 Percentile:17.48(Physics, Multidisciplinary)

We have measured the activation cross sections producing $$^{64}$$Cu and $$^{67}$$Cu, promising medical radioisotopes for molecular imaging and radioimmunotherapy, by bombarding a natural zinc sample with 14 MeV neutrons. We estimated the production yields of $$^{64}$$Cu and $$^{67}$$Cu by fast neutrons from $$^{nat}$$C(d,n) with 40 MeV 5 mA deuterons. The calculated $$^{64}$$Cu yield is 1.8 TBq (175 g $$^{64}$$Zn) for 12 h of irradiation; the yields of $$^{67}$$Cu by $$^{67}$$Zn(n,p)$$^{67}$$Cu and $$^{68}$$Zn(n,x)$$^{67}$$Cu were 249 GBq (184 g $$^{67}$$Zn) and 287 GBq (186 g $$^{68}$$Zn) at the end of 2 days of irradiation, respectively. From the results, we proposed a new route to produce $$^{67}$$Cu with very little radionuclide impurity via the $$^{68}$$Zn(n,x)$$^{67}$$Cu reaction, and showed the $$^{64}$$Zn(n,p)$$^{64}$$Cu reaction to be a promising route to produce $$^{64}$$Cu.

Journal Articles

Problems in clinical practice of domestic supply of $$^{99}$$Mo/$$^{rm 99m}$$Tc; Development of $$^{99}$$Mo/$$^{rm 99m}$$Tc production using accelerator neutrons

Nagai, Yasuki

Radioisotopes, 61(12), p.619 - 624, 2012/12

A new method was proposed to produce $$^{99}$$Mo by the $$^{100}$$Mo(n,2n)$$^{99}$$Mo reaction using intense neutrons from an accelerator by us. About 20% of the demand of $$^{99}$$Mo in Japan could be obtained constantly by the proposed method. In fact, we have shown that the produced $$^{99}$$Mo contained very little RI impurity and the radionuclide purity of $$^{rm 99m}$$Tc separated from $$^{99}$$Mo by sublimation and the labeling efficiency of $$^{rm 99m}$$Tc-MDP exceed the United States Pharmacopeia requirements for a fission product, $$^{99}$$Mo. We expect that the present $$^{99}$$Mo production method will be accepted worldwide to ensure the constant domestic supply of $$^{99}$$Mo.

Journal Articles

Radioactive tracer $$^{132}$$Cs (TRACs) for Fukushima Nuclear Power Plant accident

Nagai, Yasuki; Makii, Hiroyuki; Namiki, Shinji; Iwamoto, Osamu; Iwamoto, Nobuyuki; Sawahata, Hiroyuki*

Journal of the Physical Society of Japan, 81(8), p.085003_1 - 085003_2, 2012/08

 Times Cited Count:0 Percentile:100(Physics, Multidisciplinary)

We propose to use the radionuclide $$^{132}$$Cs as a tracer. $$gamma$$-ray energy of the most intense line from the decay of $$^{132}$$Cs is 668 keV, which is very near to that of the 662 keV from the decay of $$^{137}$$Cs, while the half-life of $$^{132}$$Cs is 6.5 d. $$^{132}$$Cs can be produced by nuclear reactions such as $$^{133}$$Cs(n,2n)$$^{132}$$Cs, $$^{133}$$Cs(r,n)$$^{132}$$Cs or $$^{132}$$Xe(p,n)$$^{132}$$Cs. The $$^{132}$$Cs tracer would be useful in the quantitative studies of radionuclide $$^{137}$$Cs contaminant in human, and in any experimental studies in the minimization of radionuclide $$^{137}$$Cs contamination in agricultural and stock farming products.

Journal Articles

Isotope production for medical usage using fast neutron reactions

Hatsukawa, Yuichi; Nagai, Yasuki; Kin, Tadahiro; Segawa, Mariko; Harada, Hideo; Iwamoto, Osamu; Iwamoto, Nobuyuki; Ochiai, Kentaro; Takakura, Kosuke; Konno, Chikara; et al.

Proceedings in Radiochemistry, 1(1), p.327 - 329, 2011/09

Authors proposed a new route to produce $$^{99}$$Mo by the $$^{100}$$Mo($$n$$,2$$n$$)$$^{99}$$Mo reaction, which has some characteristic features. Such as the reaction cross section is large, about 1.5 barn at 12 $$<$$ $$E$$$$_{rm n}$$ $$<$$ 17 MeV, which is 10 times larger than the thermal-neutron capture cross section of $$^{98}$$Mo. Second, the cross sections of the ($$n$$,$$alpha$$), ($$n$$,$$np$$), and ($$n$$,$$p$$) reactions are less than a few mb at $$E$$$$_{rm n}$$ = 14 MeV. Third, a large amount of $$^{100}$$Mo target materials can be used, compared to that for proton beam irradiation on $$^{100}$$Mo. Fourth, intense neutrons with energy of 12-17 MeV are already available. In the present work we have measured all $$gamma$$-rays emitted from activities produced by bombarding a natural Mo target with neutrons from the D($$^3$$H,$$n$$)$$^4$$He reaction at Fusion Neutronics Source Facility (FNS) at Japan Atomic Energy Agency (JAEA) to study characteristic features mentioned above more in detail. The neutron flux was about 10$$^{12}$$n/cm$$^2$$s. The experimental results at FNS will be discussed in the conference.

Journal Articles

Design of a 4$$pi$$ LaBr$$_{3}$$(Ce) spectrometer for neutron capture cross section measurements

Goto, Jun*; Harada, Hideo; Kitatani, Fumito; Nagai, Yasuki; Oshima, Masumi; Segawa, Mariko; Toh, Yosuke

Journal of the Korean Physical Society, 59(2), p.1585 - 1588, 2011/08

 Times Cited Count:2 Percentile:77.61(Physics, Multidisciplinary)

A 4$$pi$$ LaBr$$_{3}$$(Ce) spectrometer was designed for the measurements of neutron capture cross sections using a prompt $$gamma$$-ray spectroscopic method with a time-of-flight technique. An optimum configuration for the 4$$pi$$ LaBr$$_{3}$$(Ce) spectrometer was adopted from four possible configurations based on comparison of simulated performance and cost of construction. Further simulations were performed to demonstrate performance of the 4$$pi$$ LaBr$$_{3}$$(Ce) spectrometer.

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