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Journal Articles

Applying image recognition technology by convolutional neural networks to mountain plot images

Nomura, Masahiro; Tamura, Fumihiko; Shimada, Taihei; Yamamoto, Masanobu; Furusawa, Masashi*; Sugiyama, Yasuyuki*; Hara, Keigo*; Hasegawa, Katsushi*; Omori, Chihiro*; Yoshii, Masahito*

Proceedings of 17th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.64 - 67, 2020/09

Image recognition using a convolutional neural network (CNN) has been used in a wide range of fields and has produced excellent results. If this image recognition technology is used effectively, it should be possible to obtain information from an image equal to or more than the information that a person can obtain from an image. At J-PARC, researchers with specialized knowledge obtain beam information needed to adjust the equipment from an image called mountain plot. In this study, we applied the image recognition technology by using CNN to this mountain plot image, and tried to obtain the information about the beam necessary for adjustment. As a result, we were able to obtain more information than is currently available by using the image recognition technology. In the future, we plan to adjust the equipment based on the information actually obtained from the image recognition technology and confirm its effectiveness

Journal Articles

Production of $$^{266}$$Bh in the $$^{248}$$Cm($$^{23}$$Na,5$$n$$)$$^{266}$$Bh reaction and its decay properties

Haba, Hiromitsu*; Fan, F.*; Kaji, Daiya*; Kasamatsu, Yoshitaka*; Kikunaga, Hidetoshi*; Komori, Yukiko*; Kondo, Narumi*; Kudo, Hisaaki*; Morimoto, Koji*; Morita, Kosuke*; et al.

Physical Review C, 102(2), p.024625_1 - 024625_12, 2020/08

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

Journal Articles

Corrosion monitoring in humidity-controlled environment simulating gamma ray irradiation

Omori, Atsushi*; Akiyama, Eiji*; Abe, Hiroshi*; Hata, Kuniki; Sato, Tomonori; Kaji, Yoshiyuki; Inoue, Hiroyuki*; Taguchi, Mitsumasa*; Seito, Hajime*; Tada, Eiji*; et al.

Zairyo To Kankyo, 69(4), p.107 - 111, 2020/04

To evaluate the effect of oxidants, which are formed by radiolysis of water under gamma ray irradiation, on the corrosion of a carbon steel in humid environment, ozone was introduced as a model oxidant in to humidity-controlled air at 50$$^{circ}$$C in a thermo-hygrostat chamber. Corrosion monitoring was performed by using an Atmospheric Corrosion Monitor-type (ACM) sensor consisting of a carbon steel anode and an Ag cathode. The output current of the ACM sensor was increased with the increase in relative humidity and it was obviously increased with the increase in the introduced ozone concentration at each relative humidity. The results indicate that ozone accelerates the corrosion of the carbon steel. The effect of ozone on the corrosion acceleration is attributed to the fast reduction reaction and fast dissolution reaction in to water compared to that of oxygen.

Journal Articles

Simulations of beam loading compensation in a wideband accelerating cavity using a circuit simulator including a LLRF feedback control

Tamura, Fumihiko; Yamamoto, Masanobu; Sugiyama, Yasuyuki*; Yoshii, Masahito*; Omori, Chihiro*; Shimada, Taihei; Nomura, Masahiro; Hasegawa, Katsushi*; Hara, Keigo*; Furusawa, Masashi*

Journal of Physics; Conference Series, 1350(1), p.012189_1 - 012189_7, 2019/12

 Times Cited Count:0 Percentile:100

Magnetic alloy cavities are employed in the J-PARC RCS to generate high accelerating voltages. The cavity, which is driven by a vacuum tube amplifier, has a wideband frequency response and the beam loading in the cavity is multiharmonic. Therefore, the tube must generate a multiharmonic output current. An LTspice circuit model is developed to analyze the vacuum tube operation and the compensation of the multiharmonic beam loading. The model includes the cavity, tube amplifier, beam current, and LLRF feedback control. The feedback control consists of the I/Q demodulator including low pass filters, PI control, and I/Q modulator. In this presentation, we present the implementation of the LLRF functions in the LTspice simulations. The preliminary simulation results are also presented. The simulations fairly agree with the beam test results.

Journal Articles

Multiharmonic vector rf voltage control for wideband cavities driven by vacuum tube amplifiers in a rapid cycling synchrotron

Tamura, Fumihiko; Sugiyama, Yasuyuki*; Yoshii, Masahito*; Yamamoto, Masanobu; Omori, Chihiro*; Nomura, Masahiro; Shimada, Taihei; Hasegawa, Katsushi*; Hara, Keigo*; Furusawa, Masashi*

Physical Review Accelerators and Beams (Internet), 22(9), p.092001_1 - 092001_22, 2019/09

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

Beam loading compensation in the rf cavities is a key for acceleration of high intensity beams in 3 GeV RCS of the J-PARC. Since we employ wideband magnetic alloy rf cavities for the J-PARC RCS and the wake voltage contains several harmonics, a multiharmonic beam loading compensation is required. The multiharmonic rf feedforward for the most important six harmonics is implemented in the existing low level rf (LLRF) control system, which has been working fairly well for acceleration of high intensity beams of up to 1 MW. However, we found the degradation of the performance for compensation of the feedforward with very high intensity beams. Therefore, a multiharmonic vector rf voltage control has been developed. The detail of system configuration, commissioning methodology, and beam test results using very high intensity beams are described. The beam loading by the 1 MW equivalent beam in the cavity is successfully compensated.

Journal Articles

Applying neural networks to investigations of the influence of weather conditions on the power consumption of J-PARC

Nomura, Masahiro; Tamura, Fumihiko; Shimada, Taihei; Yamamoto, Masanobu; Furusawa, Masashi*; Sugiyama, Yasuyuki*; Hara, Keigo*; Hasegawa, Katsushi*; Omori, Chihiro*; Yoshii, Masahito*

Proceedings of 16th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.258 - 261, 2019/07

In recent years, summer temperatures have tended to increase, so understanding the amount of power consumption in summer from weather information has become important in terms of contract power and power saving measures. The relationship between the amount of power consumption and weather conditions is that the accelerator facility has many cooling facilities, so it can be thought that the amount of power used to cool each device increases as the temperature and humidity increase. It seems that it has not been investigated specifically what kind of dependence there is. Therefore, considering the neural network as a kind of fitting function or a model of calculation, we investigated the influence of weather conditions on the power consumption. As a result, it was found that the power consumption of the accelerators mostly depends only on the temperature, and the electric power of Linac and RCS increases by about 1 MW when the temperature of Mito rises by 10$$^{circ}$$C.

Journal Articles

Extraction behavior of rutherfordium as a cationic fluoride complex with a TTA chelate extractant from HF/HNO $$_{3}$$ acidic solutions

Yokoyama, Akihiko*; Kitayama, Yuta*; Fukuda, Yoshiki*; Kikunaga, Hidetoshi*; Murakami, Masashi*; Komori, Yukiko*; Yano, Shinya*; Haba, Hiromitsu*; Tsukada, Kazuaki; Toyoshima, Atsushi*

Radiochimica Acta, 107(1), p.27 - 32, 2019/01

 Times Cited Count:1 Percentile:58.8(Chemistry, Inorganic & Nuclear)

Journal Articles

Baseband simulation model of the vector rf voltage control system for the J-PARC RCS

Tamura, Fumihiko; Sugiyama, Yasuyuki*; Yoshii, Masahito*; Omori, Chihiro*; Yamamoto, Masanobu; Shimada, Taihei; Nomura, Masahiro; Hasegawa, Katsushi*; Hara, Keigo*; Furusawa, Masashi*

Journal of Physics; Conference Series, 1067, p.072030_1 - 072030_6, 2018/10

 Times Cited Count:1 Percentile:33.44

Vector RF voltage feedback control for the wideband magnetic alloy cavity of the J-PARC RCS is considered to be employed to compensate the heavy beam loading caused by high intensity proton beams. A prototype system of multiharmonic RF vector voltage control has been developed and is under testing. To characterize the system performance, full RF simulations could be performed by software like Simulink, while the software is proprietary and expensive. Also, it requires much computing power and time. We performed the simplified baseband simulations of the system in z-domain by using free software, Scilab and Python control library. It seems to be beneficial for searching the parameters that the baseband simulation can be performed quickly. In this presentation, we present the setup and results of the simulations. The simulations well reproduce the open and closed loop responses of the prototype system.

Journal Articles

Conceptual design of a single-ended MA cavity for J-PARC RCS upgrade

Yamamoto, Masanobu; Nomura, Masahiro; Shimada, Taihei; Tamura, Fumihiko; Furusawa, Masashi*; Hara, Keigo*; Hasegawa, Katsushi*; Omori, Chihiro*; Sugiyama, Yasuyuki*; Yoshii, Masahito*

Journal of Physics; Conference Series, 1067, p.052014_1 - 052014_6, 2018/10

 Times Cited Count:1 Percentile:33.44

The J-PARC RCS employs Magnetic Alloy (MA) loaded cavities. The RF power is fed by vacuum tubes in push-pull operation. We realize multi-harmonic RF driving and beam loading compensation thanks to the broadband characteristics of the MA. However, the push-pull operation has disadvantages in multi-harmonics. An unbalance of the anode voltage swing remarkably appears at very high intensity beam acceleration. We propose a single-ended MA cavity for the RCS beam power upgrade, where no unbalance arises intrinsically.

Journal Articles

Next generation LLRF control system for J-PARC RCS

Tamura, Fumihiko; Sugiyama, Yasuyuki*; Yoshii, Masahito*; Omori, Chihiro*; Yamamoto, Masanobu; Nomura, Masahiro; Shimada, Taihei; Hasegawa, Katsushi*; Hara, Keigo*; Furusawa, Masashi*

Proceedings of 15th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1131 - 1135, 2018/08

The LLRF control system for the J-PARC RCS has been playing important roles for acceleration of high intensity proton beams. The key functions of the system are the dual harmonic voltage control and the multiharmonic rf feedforward to compensate the heavy beam loading in the wideband cavities. The system has been working fine for more than ten years, however, the old FPGAs in the system are already discontinued and not supported by current development environment. Maintenance of the system will be difficult soon. We are developing the next generation LLRF control system with the new form factor, MicroTCA.4, while the existing system is based on the VME. In this article, we describe the configuration of the new system, its functions, and the status of the development.

Journal Articles

Determination of fusion barrier distributions from quasielastic scattering cross sections towards superheavy nuclei synthesis

Tanaka, Taiki*; Narikiyo, Yoshihiro*; Morita, Kosuke*; Fujita, Kunihiro*; Kaji, Daiya*; Morimoto, Koji*; Yamaki, Sayaka*; Wakabayashi, Yasuo*; Tanaka, Kengo*; Takeyama, Mirei*; et al.

Journal of the Physical Society of Japan, 87(1), p.014201_1 - 014201_9, 2018/01

 Times Cited Count:7 Percentile:26.78(Physics, Multidisciplinary)

Excitation functions of quasielastic scattering cross sections for the $$^{48}$$Ca + $$^{208}$$Pb, $$^{50}$$Ti + $$^{208}$$Pb, and $$^{48}$$Ca + $$^{248}$$Cm reactions were successfully measured by using the gas-filled recoil-ion separator GARIS. Fusion barrier distributions were extracted from these data, and compared with the coupled-channels calculations. It was found that the peak energies of the barrier distributions for the $$^{48}$$Ca + $$^{208}$$Pb and $$^{50}$$Ti + $$^{208}$$Pb systems coincide with those of the 2n evaporation channel cross sections for the systems, while that of the $$^{48}$$Ca + $$^{248}$$Cm is located slightly below the 4n evaporation ones. This results provide us helpful information to predict the optimum beam energy to synthesize superheavy nuclei.

Journal Articles

Measurement of thermal deformation of magnetic alloy cores of radio frequency cavities in 3-GeV rapid-cycling synchrotron of Japan Proton Accelerator Research Complex

Shimada, Taihei; Nomura, Masahiro; Tamura, Fumihiko; Yamamoto, Masanobu; Sugiyama, Yasuyuki*; Omori, Chihiro*; Hasegawa, Katsushi*; Hara, Keigo*; Yoshii, Masahito*

Nuclear Instruments and Methods in Physics Research A, 875, p.92 - 103, 2017/12

 Times Cited Count:0 Percentile:100(Instruments & Instrumentation)

Journal Articles

Development of a vector rf voltage control system for the J-PARC RCS

Tamura, Fumihiko; Sugiyama, Yasuyuki*; Yoshii, Masahito*; Omori, Chihiro*; Yamamoto, Masanobu; Shimada, Taihei; Hasegawa, Katsushi*; Hara, Keigo*; Furusawa, Masashi*

Proceedings of 14th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.241 - 245, 2017/12

Beam loading compensation in magnetic alloy (MA) cavities is necessary to accelerate high intensity proton beams in the J-PARC 3GeV rapid cycling synchrotron (RCS). Because of its wide frequency response, wake voltages in the cavity by the beam contain multiharmonic components and the beam loading compensation must be multiharmonics. The J-PARC RCS utilize the multiharmonic rf feedforward system for the beam loading compensation. Although the performance of the feedforward is good, we have found some limitations of performance due to the open loop configuration of the feedforward system. For the next generation LLRF control system for the RCS, we consider to employ vector rf control in addition to the feedforward for beam loading compensation. We developed a prototype of the vector rf control. The system details, commissioning methodology, and preliminary beam test results are presented.

Journal Articles

Observation of simultaneous oscillations of bunch shape and position caused by odd-harmonic beam loading in the Japan Proton Accelerator Research Complex Rapid Cycling Synchrotron

Yamamoto, Masanobu; Nomura, Masahiro; Shimada, Taihei; Tamura, Fumihiko; Hara, Keigo*; Hasegawa, Katsushi*; Omori, Chihiro*; Sugiyama, Yasuyuki*; Yoshii, Masahito*

Progress of Theoretical and Experimental Physics (Internet), 2017(11), p.113G01_1 - 113G01_24, 2017/11

 Times Cited Count:1 Percentile:81.17(Physics, Multidisciplinary)

Two proton bunches circulates the accelerator ring in the J-PARC 3GeV synchrotoron (RCS). The accelerating voltage is also generated in twice of the revolution frequency. The major Fourier component of the wake voltage should become even harmonics. However, the odd harmonics grow and cause a large number of beam loss. The beam measurement suggests that the odd harmonic wake voltages promote oscillations of not only the bunch position but also the bunch shape. The oscillations continue because they amplify the odd harmonic beam components. A particle tracking simulation can reproduce these simultaneous oscillations. It is found that the odd harmonic wake voltages lead to severe rf bucket distortion that results in beam loss. As a result, introducing a beam loading compensation system for the minor harmonics can prevent the beam loss and it would contribute the stable accelerator operation with the reduction of the activation.

Journal Articles

Study of the reaction $$^{48}$$Ca + $$^{248}$$Cm $$rightarrow$$ $$^{296}$$Lv$$^{ast}$$ at RIKEN-GARIS

Kaji, Daiya*; Morita, Kosuke*; Morimoto, Koji*; Haba, Hiromitsu*; Asai, Masato; Fujita, Kunihiro*; Gan, Z.*; Geissel, H.*; Hasebe, Hiroo*; Hofmann, S.*; et al.

Journal of the Physical Society of Japan, 86(3), p.034201_1 - 034201_7, 2017/03

 Times Cited Count:13 Percentile:18.84(Physics, Multidisciplinary)

The fusion reaction of $$^{48}$$Ca + $$^{248}$$Cm $$rightarrow$$ $$^{296}$$Lv$$^{ast}$$ was studied using the gas-filled recoil-ion separator GARIS at RIKEN. A total of seven $$alpha$$ and spontaneous-fission decay chains were observed, which would originate from the reaction products of the element 116, $$^{292}$$Lv and $$^{293}$$Lv. Decay properties observed in the chains are in good agreement with the previously published ones. However, one of the chains showed a discrepancy, indicating the new spontaneous-fission branch in $$^{285}$$Cn or the production of the new isotope $$^{294}$$Lv.

Journal Articles

Complex chemistry with complex compounds

Eichler, R.*; Asai, Masato; Brand, H.*; Chiera, N. M.*; Di Nitto, A.*; Dressler, R.*; D$"u$llmann, Ch. E.*; Even, J.*; Fangli, F.*; Goetz, M.*; et al.

EPJ Web of Conferences, 131, p.07005_1 - 07005_7, 2016/12

 Times Cited Count:1 Percentile:48.2

In recent years gas-phase chemical studies assisted by physical pre-separation allowed for the productions and investigations of fragile single molecular species of superheavy elements. The latest highlight is the formation of very volatile hexacarbonyl compound of element 106, Sg(CO)$$_{6}$$. Following this success, second-generation experiments were performed to measure the first bond dissociation energy between the central metal atom and the surrounding ligand. The method using a tubular decomposition reactor was developed and successfully applied to short-lived Mo(CO)$$_{6}$$, W(CO)$$_{6}$$, and Sg(CO)$$_{6}$$.

Journal Articles

Vacuum tube operation analysis under multi-harmonic driving and heavy beam loading effect in J-PARC RCS

Yamamoto, Masanobu; Nomura, Masahiro; Shimada, Taihei; Tamura, Fumihiko; Hara, Keigo*; Hasegawa, Katsushi*; Omori, Chihiro*; Toda, Makoto*; Yoshii, Masahito*; Schnase, A.*

Nuclear Instruments and Methods in Physics Research A, 835, p.119 - 135, 2016/11

 Times Cited Count:3 Percentile:57.46(Instruments & Instrumentation)

A magnetic alloy loaded cavity is used to generate multi-harmonic rf voltage in J-PARC RCS. However, a vacuum tube operation analysis under the multi-harmonic driving is very complicated because many variables should be solved with a self consistency. At the conventional operation analysis, a hand work by tracing the constant current curve of the tube was performed, or an appropriate single harmonic wave form was assumed. We have developed a numerical analysis code which calculates the vacuum tube operation automatically and it realizes the multi-harmonic vacuum tube operation analysis. The code is verified at the high power beam acceleration test and we confirm the calculation results are consistent with the measurement ones. We can calculate the vacuum tube operation precisely by using the code, and it will contribute to improving the quality of the beam in the high intensity proton synchrotron.

Journal Articles

Cavity voltage variation at beam extraction in the J-PARC MR

Tamura, Fumihiko; Yoshii, Masahito*; Omori, Chihiro*; Yamamoto, Masanobu; Nomura, Masahiro; Shimada, Taihei; Hasegawa, Katsushi*; Hara, Keigo*

Proceedings of 13th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.808 - 810, 2016/11

J-PARC MR provides high intensity proton beams of 390 kW to the neutrino experiment. The proton beams are extracted by fast extraction. It has been found that the cavity voltage goes up for about 20 $$mu$$s just after extraction. It is because the rf feed forward system for beam loading compensation outputs compensation signals for its system delay. The MR cavity has a relatively low Q value of 22 and the cavity voltage can varies in the order of 10 $$mu$$s. The voltage variation of the cavity voltage increases with the beam intensity and it is a possible reason of the damage of the gap capacitors. A counter measure using the inhibit function of the summation amplifier in the LLRF system has been applied. In this presentation, we present the details of the cavity voltage variation and the results of the counter measure. Also, we present the analysis of beam loading using the voltage variation.

Journal Articles

Simulation of beam behavior caused by odd harmonics of beam loading in J-PARC RCS

Yamamoto, Masanobu; Nomura, Masahiro; Shimada, Taihei; Tamura, Fumihiko; Hara, Keigo*; Hasegawa, Katsushi*; Omori, Chihiro*; Toda, Makoto*; Yoshii, Masahito*

Proceedings of 7th International Particle Accelerator Conference (IPAC '16) (Internet), p.3443 - 3445, 2016/06

The J-PARC RCS accelerates 2 bunches at the harmonic number 2. The major Fourier component of the beam current is even harmonics. However, the odd harmonics grow under some conditions even though they are very small amplitude at the beginning. Particle tracking simulation suggests that the displacement and the deformation of the bunch are caused by the odd harmonics, it is synchronized with the potential distortion, and it results in the beam instability. We describe the particle tracking simulation results for the odd harmonic beam loading effect in the RCS.

Journal Articles

Collapse evaluation of double notched stainless pipes subjected to combined tension and bending

Suzuki, Ryosuke*; Matsubara, Masaaki*; Yanagihara, Seiji*; Morijiri, Mitsugu*; Omori, Atsushi*; Wakai, Takashi

Procedia Materials Science, 12, p.24 - 29, 2016/00

 Times Cited Count:2 Percentile:17.21

In this study, the plastic collapse strength of asymmetry multiple circumferential notched stainless steel pipes subjected to combined axial tension and bending is investigated experimentally and is compared with the theoretical plastic collapse strength. In addition, the potential is discussed for the simplification of structural integrity evaluation of multiple cracked piping. The integrity of the asymmetry multiple circumferential notched stainless steel pipes subjected to combined axial tension and bending can be evaluated conservatively using the theoretical plastic collapse strength for the pipe with multiple notches calculated based on the elastic-perfectly plastic model.

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