Si-addition contributes to overcoming the strength-ductility trade-off in high-entropy alloys

Wei, D.*; Gong, W.; Tsuru, Tomohito; Lobzenko, I.; Li, X.*; Harjo, S.; Kawasaki, Takuro; Do, H.-S.*; Bae, J. W.*; Wagner, C.*; et al.

International Journal of Plasticity, 159, p.103443_1 - 103443_18, 2022/12

https://doi.org/10.1016/j.ijplas.2022.103443

Spin excitations in optimally P-doped BaFe(AsP) superconductor

Hu, D.*; Yin, Z.*; Zhang, W.*; Ewings, R. A.*; Ikeuchi, Kazuhiko*; Nakamura, Mitsutaka; Roessli, B.*; Wei, Y.*; Zhao, L.*; Chen, G.*; et al.

Physical Review B, 94(9), p.094504_1 - 094504_7, 2016/09

AA2016-0252.pdf:2.18MB

https://doi.org/10.1103/PhysRevB.94.094504

The temperature and energy dependence of spin excitations in an optimally P-doped BaFe(AsP) superconductor (T = 30 K) were studied by using inelastic neutron scattering. Experimental results are consistent with calculations from a combined density functional theory and dynamical mean field theory, and suggest that the decreased average pnictogen height in BaFe(AsP) reduces the strength of electron correlations and increases the effective bandwidth of magnetic excitation.

Beam start-up of J-PARC linac after the Tohoku Earthquake

Ikegami, Masanori*; Fang, Z.*; Futatsukawa, Kenta*; Miyao, Tomoaki*; Maruta, Tomofumi; Sako, Hiroyuki; Miura, Akihiko; Wei, G.; Tamura, Jun

Proceedings of 3rd International Particle Accelerator Conference (IPAC '12) (Internet), p.3293 - 3295, 2012/05

http://accelconf.web.cern.ch/accelconf/IPAC2012/papers/thppc010.pdf

no abstracts in English

Longitudinal beam acceptance of J-PARC drift tube linac

Maruta, Tomofumi; Miura, Akihiko; Sako, Hiroyuki; Wei, G.; Ikegami, Masanori*

Proceedings of 2nd International Particle Accelerator Conference (IPAC 2011) (Internet), p.2592 - 2594, 2011/09

http://accelconf.web.cern.ch/accelconf/ipac2011/papers/weps046.pdf

Since we have no tool to measure the longitudinal beam profile at the J-PARC linac, we have tuned operational parameters for the matching of both longitudinal and transverse directions only from the measurement of the transverse beam profile by wire scanners at matching sections. Therefore it is very useful for us if the beam profile on the longitudinal phase space can be measured. It motivated us to measure the longitudinal acceptance of the DTL. In the measurement, we introduced a "tank level scan" to measure the shrinkage of the acceptance when we reduce the tank level of 1st DTL cavity in addition to the conventional phase scan. In this presentation, we will present the measurement scheme and experimental results.

Azimuthal correlations of electrons from heavy-flavor decay with hadrons in and Au+Au collisions at = 200 GeV

Adare, A.*; Afanasiev, S.*; Aidala, C.*; Ajitanand, N. N.*; Akiba, Yasuyuki*; Al-Bataineh, H.*; Alexander, J.*; Aoki, Kazuya*; Aphecetche, L.*; Aramaki, Y.*; et al.

Physical Review C, 83(4), p.044912_1 - 044912_16, 2011/04

https://doi.org/10.1103/PhysRevC.83.044912

Measurements of electrons from the decay of open-heavy-flavor mesons have shown that the yields are suppressed in Au+Au collisions compared to expectations from binary-scaled collisions. Here we extend these studies to two particle correlations where one particle is an electron from the decay of a heavy flavor meson and the other is a charged hadron from either the decay of the heavy meson or from jet fragmentation. These measurements provide more detailed information about the interaction between heavy quarks and the quark-gluon matter. We find the away-side-jet shape and yield to be modified in Au+Au collisions compared to collisions.

Residual gas pressure dependence of beam loss

Miura, Akihiko; Sako, Hiroyuki; Wei, G.; Ikegami, Masanori*

Proceedings of 25th International Linear Accelerator Conference (LINAC 2010) (CD-ROM), p.587 - 589, 2010/09

http://accelconf.web.cern.ch/AccelConf/LINAC2010/papers/tup075.pdf

Residual gas in beam line essentially affects the beam loss and residual radiation on the accelerator. It is important to understand a cause of beam loss and relation between beam loss and residual gas pressure. We measured beam loss at the normal and worse vacuum condition in both SDTL and A0BT sections. The result indicates that the beam loss depends on the residual gas pressure and position where the beam loss occurs is about 20 to 30 meter downstream. This suggests the optimum position for installation of vacuum system to minimize the beam loss. In this paper, we describe the experimental result and its discussions. In addition, the cause of the beam loss is considered to be a stripping from negative hydrogen ions to neutral hydrogen atoms (H).

Reduction of transverse emittance growth in J-PARC linac DTL

Sako, Hiroyuki; Wei, G.; Miura, Akihiko; Ikegami, Masanori*

Proceedings of 25th International Linear Accelerator Conference (LINAC 2010) (CD-ROM), p.563 - 565, 2010/09

http://accelconf.web.cern.ch/AccelConf/LINAC2010/papers/tup067.pdf

In J-PARC linac at 15 mA, horizontal and vertical emittance after DTL is reduced by 12% and 10%, respectively by setting the amplitudes of the first and second bunchers to 120% and 90% with respect to the designed settings. The resulting normalized horizontal and vertical emittance is 0.230 and 0.205 mm mrad. At 20 mA measured in Jan 2010, horizontal and vertical rms emittance is reduced by 17% and 10% respectively by setting the amplitudes of the first and second bunchers to 110% and 80% with respect to the designed settings. The resulting normalized horizontal and vertical emittance is 0.273 and 0.253 mm mrad. At 15 mA, we further investigated dependence of emittance on quadrupole magnetic field in MEBT1. With the most downstream quadruple magnet field at MEBT1 enhanced by 20% from the designed values, the emittance is further reduced to 0.171 and 0.200 mm mrad. These results are compared with the IMPACT simulation.

Beam injection tuning of the J-PARC main ring

Wei, G.; Koseki, Tadashi*; Igarashi, Susumu*; Tomizawa, Masahito*; Takano, Jumpei*; Ishii, Koji*; Shirakata, Masashi*; Fan, K.*; Hatakeyama, Shuichiro; Uota, Masahiko*; et al.

Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.3915 - 3917, 2010/05

http://accelconf.web.cern.ch/AccelConf/IPAC10/papers/thpeb015.pdf

Recent progress in the beam commissioning of J-PARC linac

Ikegami, Masanori*; Sako, Hiroyuki; Miura, Akihiko; Wei, G.

Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.774 - 776, 2010/05

http://accelconf.web.cern.ch/AccelConf/IPAC10/papers/mopd041.pdf

Since Nov. 2007, the linac beam power has been increased from 1.2 kW to 7.2 kW corresponding to 120 kW at the 3-GeV synchrotron (RCS). We also performed 18-kW high-power test corresponding to 300 kW at RCS, which is equivalent to the design power for the present hardware configuration. In the course of beam power ramp-up, we have identified beam loss mechanisms and succeeded to mitigate them.

Amphoteric ion exchange membrane synthesized by radiation-induced graft copolymerization of styrene and dimethylaminoethyl methacrylate into PVDF film for vanadium redox flow battery applications

Qiu, J.*; Zhang, J.*; Chen, J.; Peng, J.*; Xu, L.*; Zhai, M.*; Li, J.*; Wei, G.*

Journal of Membrane Science, 334(1-2), p.9 - 15, 2009/05

https://doi.org/10.1016/j.memsci.2009.02.009

Poly(vinylidene difluoride) (PVDF) film was grafted with styrene (St) and dimethylaminoethyl methacrylate (DMAEMA) using irradiation techniques. Through subsequent sulfonation and protonation processes, a new kind of amphoteric ion exchange membrane (AIEM) was synthesized. The grafting yield () increased with absorbed dose and leveled off at about 60 kGy. The properties of the AIEM strongly depended on the composition and of the film, i.e. higher content of DMAEMA brought lower permeability of vanadium ions and conductivity. Finally, an AIEM was assembled and tested in the vanadium redox flow battery (VRFB) system. It was found that the VRFB assembled with the AIEM maintained an open circuit voltage (OCV) higher than 1.2V after placed for 68h, which was much longer than that with the Nafion117 membrane. Therefore, this work provides a novel method to develop potential substitute of Nafion membranes to be applied in VRFB system.