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Journal Articles

Hadronic Paschen-Back effect

Iwasaki, Sachio; Oka, Makoto; Suzuki, Kei*; Yoshida, Tetsuya*

Physics Letters B, 790, p.71 - 76, 2019/03

We find a novel phenomenon induced by the interplay between a strong magnetic field and finite orbital angular momenta in hadronic systems, which is analogous to the Paschen-Back effect observed in the field of atomic physics. This effect allows the wave functions to drastically deform. We discuss anisotropic decay from the deformation as a possibility to measure the strength of the magnetic field in heavy-ion collision at LHC, RHIC and SPS, which has not experimentally been measured. As an example we investigate charmonia with finite orbital angular momentum in a strong magnetic field. We calculate the mass spectra and mixing rate. To obtain anisotropic wave functions, we apply the cylindrical Gaussian expansion method, where the Gaussian bases to expand the wave functions have different widths along transverse and longitudinal directions in the cylindrical coordinate.

Journal Articles

Studies of extremely dense matter in heavy-ion collisions at J-PARC

Sako, Hiroyuki

Nuclear Physics A, 982, p.959 - 962, 2019/02

to study extremely dense matter in heavy-ion collisions at 1-19 AGeV/c at a future project of J-PARC (JPARC-HI). We will search for the first order phase boundary and its critical end point in the QCD phase diagram. We also aim at studying the properties of dense matter related to neutron stars and neutron star mergers, in particular the equation of state (EOS). We expect to produce world's highest rate heavy-ion beams of $$10^{11}$$ with the ion species from p to U. We design spectrometers based on a large dipole magnet to measure hadrons, dimuons, and hypernuclei. We evaluate some of key performance of the spectrometers based on detailed simulations.

Journal Articles

$$^{239}$$Pu nuclear magnetic resonance in the candidate topological insulator PuB$$_4$$

Dioguardi, A. P.*; Yasuoka, Hiroshi*; Thomas, S. M.*; Sakai, Hironori; Cary, S. K.*; Kozimor, S. A.*; Albrecht-Schmitt, T. E.*; Choi, H. C.*; Zhu, J.-X.*; Thompson, J. D.*; et al.

Physical Review B, 99(3), p.035104_1 - 035104_6, 2019/01

We present a detailed nuclear magnetic resonance (NMR) study of $$^{239}$$Pu in bulk and powdered single-crystal plutonium tetraboride (PuB$$_4$$), which has recently been investigated as a potential correlated topological insulator. The $$^{239}$$Pu NMR spectra are consistent with axial symmetry of the shift tensor showing for the first time that $$^{239}$$Pu NMR can be observed in an anisotropic environment and up to room temperature. The temperature dependence of the $$^{239}$$Pu shift, combined with a relatively long spin-lattice relaxation time ($$T_1$$), indicate that PuB$$_4$$ adopts a nonmagnetic state with gaplike behavior consistent with our density functional theory calculations. The temperature dependencies of the NMR Knight shift and $$T^{-1}$$ imply bulk gaplike behavior confirming that PuB$$_4$$ is a good candidate topological insulator.

Journal Articles

Spectroscopy of strongly deformed $$^{32}$$Ne by proton knockout reactions

Murray, I.*; MacCormick, M.*; Bazin, D.*; Doornenbal, P.*; Aoi, Nori*; Baba, Hidetada*; Crawford, H. L.*; Fallon, P.*; Li, K.*; Lee, J.*; et al.

Physical Review C, 99(1), p.011302_1 - 011302_7, 2019/01

理化学研究所のRI Beam Factory(RIBF)にて中性子過剰核$$^{32}$$Neの低励起状態を1陽子あるいは2陽子ノックアウト反応によって生成し、そこからの脱励起ガンマ線の測定によって、エネルギー準位を構築した。1410(15)keVのガンマ線を初めて測定し、反応断面積の系統性などから$$4^+_1$$から$$2^+_1$$への遷移に対応すると提案した。既に知られている$$2^+_1$$準位を用いて、$$4^+_1$$$$2^+_1$$の励起エネルギー比2.99(6)が得られた。この値は、回転スペクトルの値に近く、$$^{32}$$Neは強く変形していることがわかった。この実験結果は、大規模殻模型計算の結果とよく一致した。

Journal Articles

$$g$$-factor measurement of the 2738 keV isomer in $$^{135}$$La

Laskar, Md. S. R.*; Saha, S.*; Palit, R.*; Mishra, S. N.*; Shimizu, Noritaka*; Utsuno, Yutaka; Ideguchi, Eiji*; Naik, Z.*; Babra, F. S.*; Biswas, S.*; et al.

Physical Review C, 99(1), p.014308_1 - 014308_6, 2019/01

タタ基礎物理学研究所の重イオン加速器にて、$$^{11}$$B($$^{128}$$Te, 4n)$$^{135}$$La反応によって$$^{135}$$Laの励起状態を生成し、2738keVにあるアイソマーの$$g$$因子を時間微分型摂動角分布(TDPAD)法によって測定した。得られた$$g$$因子の値は$$-0.049(3)$$であった。このアイソマーの核構造を理解するため、$$^{135}$$Laに対し、大規模殻模型計算を行った。殻模型計算は低励起状態のバンド構造を非常によく再現し、2738keVのアイソマーのスピンパリティは$$23/2^+$$であることを強く示唆する結果が得られた。このアイソマーは、$$^{134}$$Baの$$10^+_1$$$$d_{5/2}$$軌道にいる陽子が結合してできる配位が主であると解釈された。

Journal Articles

Nuclear structure of $$^{76}$$Ni from the ($$p$$,$$2p$$) reaction

Elekes, Z.*; Kripk$'o$, $'A$*; Sohler, D.*; Sieja, K.*; Ogata, Kazuyuki*; Yoshida, Kazuki; Doornenbal, P.*; Obertelli, A.*; Authelet, G.*; Baba, Hidetada*; et al.

Physical Review C, 99(1), p.014312_1 - 014312_7, 2019/01

The nuclear structure of the $$^{76}$$Ni nucleus was investigated by ($$p$$,$$2p$$) reaction using a NaI(Tl) array to detect the deexciting prompt $$gamma$$ rays. A new transition with an energy of 2227 keV was identified by $$gamma gamma$$ and $$gamma gamma gamma$$ coincidences. Our shell-model calculations using the Lenzi, Nowacki, Poves, and Sieja interaction produced good candidates for the experimental proton hole states in the observed energy region, and the theoretical cross sections showed good agreement with the experimental values. Although we could not assign all the experimental states to the theoretical ones unambiguously, the results are consistent with a reasonably large Z = 28 shell gap for nickel isotopes in accordance with previous studies.

Journal Articles

Further signatures to support the tetraquark mixing framework for the two light-meson nonets

Kim, H.*; Kim, K. S.*; Cheoun, M.-K.*; Jido, Daisuke*; Oka, Makoto

Physical Review D, 99(1), p.014005_1 - 014005_15, 2019/01

We investigate additional signatures to support the tetraquark mixing framework that has been recently proposed as a possible structure for the two nonets. We reexamine the mass ordering generated from the tetraquark nonets and show that this mass ordering is satisfied by the two nonets although the ordering in the heavy nonet is marginal. The marginal mass ordering can be regarded as another signature for tetraquarks because it can be explained partially by the hyperfine masses calculated from the tetraquark mixing framework. As a peculiar signature distinguished from the other approaches, we investigate the fall-apart coupling strengths into two vector mesons from our tetraquarks. Coupling strengths into the two-vector modes are found to enhance strongly in the heavy nonet while they are suppressed in the light nonet. The coupling ratios are found to be huge. This trend in the two-vector modes can provide another testing ground for the tetraquark mixing framework. Some experimental evidence related to the phenomena is discussed particularly from the resonances belonging to the heavy nonet.

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

The aim of this study was to identify relevant Rf chemical species by using reversed-phase extraction chromatography with 2-thenoyltrifluoroacetone (TTA) resin as the stationary phase. Because TTA can be used to extract specific metal ions, the distribution ratios of the system enabled determination of the specific complex formation constant of Rf. We performed several experiments on chemical systems with Zr, Hf, No, and Rf, determined their adsorption coefficients, and deduced the K values for Rf.

JAEA Reports

Proceedings of the 2017 Symposium on Nuclear Data; November 16-17, 2017, iVil, Tokai-mura, Ibaraki, Japan

Nishio, Katsuhisa; Utsuno, Yutaka; Chiba, Satoshi*; Koura, Hiroyuki; Iwamoto, Osamu; Nakamura, Shoji

JAEA-Conf 2018-001, 226 Pages, 2018/12

JAEA-Conf-2018-001.pdf:22.81MB

The 2017 Symposium on Nuclear Data was held at iVil in Tokai on November 16-17, 2017. The symposium was hosted by the Nuclear Data Division of the Atomic Energy Society of Japan (AESJ) and Advanced Science Research Center of Japan Atomic Energy Agency, and co-hosted by Japanese Nuclear Data Committee of AESJ and North Kanto Branch of AESJ. In the symposium, a tutorial was given by Prof. Rykaczewski (ORNL) "New nuclear data from total absorption spectroscopy and beta-delayed neutron measurements", as well as six oral sessions, "Nuclear Physics and Nuclear Data" (two sessions), "Nuclear Theory and Nuclear Data", "Reactors" and "Nuclear Data and Their Applications" (two sessions). In addition, recent advances in experiment, theory, evaluation, benchmark, and application were presented in the poster session. The symposium had 79 participants, who contributed to very active and fruitful discussions. This report consists of 37 papers, including those of 14 oral and 23 poster presentations.

Journal Articles

Evaluation of photocatalytic abilities by variation of conductivity and dimethyl sulfoxide; Photocatalytically active TiO$$_{2}$$-coated wire mesh prepared via a double-layer coating method

Mori, Masanobu*; Sugita, Tsuyoshi; Fujii, Kengo*; Yamazaki, Taiki*; Isaka, Mayu*; Kobayashi, Kentaro*; Iwamoto, Shinji*; Itabashi, Hideyuki*

Analytical Sciences, 34(12), p.1449 - 1453, 2018/12

The photocatalyst coating stainless-steel wire mesh (TiO$$_{2}$$-WM) was prepared by double-layer coating method. The TiO$$_{2}$$-WM was evaluated using flow analytical system, which included the reactor and conductimetric detector (FAS-CD). The DMSO decomposition test through the FAS-CD reveal that photocatalytst was stable coating on the stainless-steel wire mesh.

Journal Articles

Characterization of the shape-staggering effect in mercury nuclei

Marsh, B. A.*; Day Goodacre, T.*; Tsunoda, Yusuke*; Andreyev, A.; 41 of others*

Nature Physics, 14(12), p.1163 - 1167, 2018/12

In rare cases, the removal of a single proton (Z) or neutron (N) from an atomic nucleus leads to a dramatic shape change. These instances are crucial for understanding the components of the nuclear interactions that drive deformation. The mercuryisotopes (Z = 80) are a striking example: their close neighbours, the lead isotopes (Z = 82), are spherical and steadily shrink with decreasing N. The even-mass (A = N + Z) mercury isotopes follow this trend. The odd-mass mercury isotopes $$^{181,183,185}$$Hg, however, exhibit noticeably larger charge radii. Due to the experimental difficulties of probing extremely neutron-deficient systems, and the computational complexity of modelling such heavy nuclides, the microscopic origin of this unique shape staggering has remained unclear. Here, by applying resonance ionization spectroscopy, mass spectrometry and nuclear spectroscopy as far as $$^{177}$$Hg, we determine $$^{181}$$Hg as the shape-staggering endpoint. By combining our experimental measurements with Monte Carlo shell model calculations, we conclude that this phenomenon results from the interplay between monopole and quadrupole interactions driving a quantum phase transition, for which we identify the participating orbitals. Although shape staggering in the mercury isotopes is a unique and localized feature in the nuclear chart, it nicely illustrates the concurrence of single-particle and collective degrees of freedom at play in atomic nuclei.

Journal Articles

Radiative transitions of doubly charmed baryons in lattice QCD

Bartiyar, H.*; Can, K. U.*; Erkol, G.*; Oka, Makoto; Takahashi, Toru*

Physical Review D, 98(11), p.114505_1 - 114505_14, 2018/12

Transition amplitude of spin 3/2 double-charm baryon to spin 1/2 ground state was evaluated in the lattice QCD, the first principle.

Journal Articles

Strong correlation between ferromagnetic superconductivity and pressure-enhanced ferromagnetic fluctuations in UGe$$_2$$

Tateiwa, Naoyuki; Haga, Yoshinori; Yamamoto, Etsuji

Physical Review Letters, 121(23), p.237001_1 - 237001_6, 2018/12

We have measured magnetization at high pressure in the uranium ferromagnetic superconductor UGe$$_2$$ and analyzed the magnetic data using Takahashi's spin fluctuation theory. There is a peak in the pressure dependence of the width of the spin fluctuation spectrum in the energy space $$T_0$$ at $$P_x$$, the phase boundary of FM1 and FM2 where the superconducting transition temperature $$T_{rm sc}$$ is highest. This suggests a clear correlation between the superconductivity and pressure-enhanced magnetic fluctuations developed at $$P_x$$. The pressure effect on $${T_{rm Curie}}/{T_0}$$, where $${T_{rm Curie}}$$ is the Curie temperature, suggests that the less itinerant ferromagnetic state FM2 is changed to a more itinerant one FM1 across $$P_x$$. Peculiar features in relations between $$T_0$$ and $$T_{rm sc}$$ in uranium ferromagnetic superconductors UGe$$_2$$, URhGe and UCoGe are discussed in comparison with those in high-$$T_c$$ cuprate and heavy fermion superconductors.

Journal Articles

Phenomenological approach to study the degree of the itinerancy of the 5$$f$$ electrons in actinide ferromagnets with spin fluctuation theory

Tateiwa, Naoyuki; Posp$'i$$v{s}$il, J.*; Haga, Yoshinori; Sakai, Hironori; Matsuda, Tatsuma*; Yamamoto, Etsuji

Progress in Nuclear Science and Technology (Internet), 5, p.104 - 107, 2018/12

Uranium ferromagnetic superconductors UGe$$_2$$, URhGe and UCoGe have attracted much attention from both theoretical and experimental sides since the same 5$$f$$ electrons underlie carry both the ferromagnetism and superconductivity. Recently, we have analysed 69 uranium, 7 neptunium, and 4 plutonium ferromagnets with spin fluctuation theory originally developed for researches on itinerant ferromagnets in the 3$$d$$ transition metals and their intermetallics. The applicability of the spin fluctuation theory to the actinide 5$$f$$ system has been confirmed and the itinerant character of the 5f electrons is suggested in the actinide ferromagnets. In this conference, two results will be shown. One is the results of the analyses on 80 actinide ferromagnets and the other is the pressure dependence of the spin fluctuation parameters in UGe$$_2$$.

Journal Articles

Online chemical adsorption studies of Hg, Tl, and Pb on SiO$$_{2}$$ and Au surfaces in preparation for chemical investigations on Cn, Nh, and Fl at TASCA

Lens, L.*; Yakushev, A.*; D$"u$llmann, Ch. E.*; Asai, Masato; Ballof, J.*; Block, M.*; David, H. M.*; Despotopulos, J.*; Di Nitto, A.*; Eberhardt, K.*; et al.

Radiochimica Acta, 106(12), p.949 - 962, 2018/12

Online gas-solid adsorption studies with single atom quantities of Hg, Tl, and Pb on SiO$$_{2}$$ and Au surfaces were carried out using short-lived radioisotopes with half-lives in the range of 4-49 s. This is a model study to measure adsorption enthalpies of superheavy elements Cn, Nh, and Fl. The short-lived isotopes were produced and separated by the gas-filled recoil separator TASCA at GSI. The products were stopped in He gas, and flushed into gas chromatography columns made of Si detectors whose surfaces were covered by SiO$$_{2}$$ or Au. The short-lived Tl and Pb were successfully measured by the Si detectors with the SiO$$_{2}$$ surface at room temperature. On the other hand, the Hg did not adsorb on the SiO$$_{2}$$ surface, but adsorbed on the Au surface. The results demonstrated that the adsorption properties of short-lived Hg, Tl, and Pb could be studied with this setup, and that this method is applicable to the experiment for Cn, Nh, and Fl.

Journal Articles

Electric field control of magnetic domain wall motion via modulation of the Dzyaloshinskii-Moriya interaction

Koyama, Tomohiro*; Nakatani, Yoshinobu*; Ieda, Junichi; Chiba, Daichi*

Science Advances (Internet), 4(12), p.eaav0265_1 - eaav0265_5, 2018/12

We show that the electric field (EF) can control the magnetic domain wall (DW) velocity in a Pt/Co/Pd asymmetric structure. With the application of a gate voltage, a significant change in DW velocity up to 50 m/s is observed, which is much greater than that observed in previous studies. Moreover, a DW velocity exceeding 100 m/s is clearly modulated. An EF-induced change in the interfacial Dzyaloshinskii-Moriya interaction (DMI) up to several percent is found to be the origin of the velocity modulation. The DMI-mediated velocity change shown here is a fundamentally different mechanism from that caused by EF-induced anisotropy modulation. Our results will pave the way for the electrical manipulation of spin structures and dynamics via DMI control, which can enhance the performance of spintronic devices.

Journal Articles

Vortex rectenna powered by environmental fluctuations

Lustikova, J.*; Shiomi, Yuki*; Yokoi, Naoto*; Kabeya, Noriyuki*; Kimura, Noriaki*; Ienaga, Koichiro*; Kaneko, Shinichi*; Okuma, Satoshi*; Takahashi, Saburo*; Saito, Eiji

Nature Communications, 9, p.4922_1 - 4922_6, 2018/11

A rectenna, standing for a rectifying antenna, is an apparatus which generates d.c. electricity from electric fluctuations. It is expected to realize wireless power transmission as well as energy harvesting from environmental radio waves. To realize such rectification, devices that are made up of internal atomic asymmetry such as an asymmetric junction have been necessary so far. Here we report a material that spontaneously generates electricity by rectifying environmental fluctuations without using atomic asymmetry. The sample is a common superconductor without lowered crystalline symmetry, but, just by putting it in an asymmetric magnetic environment, it turns into a rectifier and starts generating electricity. Superconducting vortex strings only annihilate and nucleate at surfaces, and this allows the bulk electrons to feel surface fluctuations in an asymmetric environment: a vortex rectenna. The rectification and generation can be switched on and off with only a slight change in temperature or external magnetic fields.

Journal Articles

Low-momentum direct-photon measurement in Cu + Cu collisions at $$sqrt{s_{_{NN}}}=200$$ GeV

Adare, A.*; Hasegawa, Shoichi; Imai, Kenichi; Nagamiya, Shoji; Sako, Hiroyuki; Sato, Susumu; Tanida, Kiyoshi; PHENIX Collaboration*; 448 of others*

Physical Review C, 98(5), p.054902_1 - 054902_11, 2018/11

We have measured direct photons for $$p_T< 5~$$GeV/$$c$$ in minimum bias and 0% - 40% most central events at midrapidity for Cu$$+$$Cu collisions at $$sqrt{s_{_{NN}}}=200$$ GeV. The $$e^{+}e^{-}$$ contribution from quasi-real direct virtual photons has been determined as an excess over the known hadronic contributions in the $$e^{+}e^{-}$$ mass distribution. A clear enhancement of photons over the binary scaled $$p$$$$+$$$$p$$ fit is observed for $$p_T < 4$$ GeV/$$c$$ in Cu$$+$$Cu data. The $$p_T$$ spectra are consistent with the Au$$+$$Au data covering a similar number of participants. The inverse slopes of the exponential fits to the excess after subtraction of the $$p$$$$+$$$$p$$ baseline are 285$$pm$$53(stat)$$pm$$57(syst)~MeV/$$c$$ and 333$$pm$$72(stat)$$pm$$45(syst)~MeV/$$c$$ for minimum bias and 0%--40% most central events, respectively. The rapidity density, $$dN/dy$$, of photons demonstrates the same power law as a function of $$dN_{rm ch}/deta$$ observed in Au$$+$$Au at the same collision energy.

Journal Articles

Change in structure between the $$I$$=1/2 states in $$^{181}$$Tl and $$^{177,179}$$Au

Cubiss, J. G.*; Barzakh, A. E.*; Andreyev, A.; 57 of others*

Physics Letters B, 786, p.355 - 363, 2018/11

The first accurate measurements of the $$alpha$$-decay branching ratio and half-life of the I$$^pi$$=1/2$$^{+}$$ ground state in $$^{181}$$Tl have been made, along with the first determination of the magnetic moments and I=1/2 spin assignments of the ground states in $$^{177,179}$$Au. The results are discussed within the complementary systematics of the reduced $$alpha$$-decay widths and nuclear g factors of low-lying, I$$^pi$$=1/2$$^{+}$$states in the neutron-deficient lead region. The findings shed light on the unexpected hindrance of the 1/2$$^{+}$$ $$rightarrow$$ 1/2$$^{+}$$, $$^{181}$$Tl$$^{g}$$ $$rightarrow$$ $$^{177}$$Au$$^{g}$$ $$alpha$$decay, which is explained by a mixing of $$pi$$3s$$_{1/2}$$and $$pi$$2d$$_{3/2}$$ configurations in $$^{177}$$Au$$^{g}$$, whilst $$^{181}$$Tl$$^{g}$$ remains a near-pure $$pi$$3s$$^{1/2}$$. This conclusion is inferred from the g factor of $$^{177}$$Au$$^{g}$$ which has an intermediate value between those of $$pi$$3s$$_{1/2}$$ and $$pi$$2d$$_{3/2}$$ states. A similar mixed configuration is proposed for the I$$^pi$$=1/2$$^{+}$$ ground state of $$^{179}$$Au. This mixing may provide evidence for triaxial shapes in the ground states in these nuclei.

Journal Articles

Magnetization study on the Ising ferromagnet URhGe with high-precision angle-resolved magnetic field near the hard axis

Nakamura, Shota*; Sakakibara, Toshiro*; Shimizu, Yusei*; Kittaka, Shunichiro*; Kono, Yohei*; Haga, Yoshinori; Pospisil, J.; Yamamoto, Etsuji

Progress in Nuclear Science and Technology (Internet), 5, p.123 - 127, 2018/11

Dc magnetization measurements have been performed on the orthorhombic Ising ferromagnet Urge. We observed a clear first-order reorientation transition with a small hysteresis and estimated the tricritical point to be around 4 K. The magnetization and the thermal expansion data indicate the presence of a characteristic temperature of about 1 K.

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