Volume 19, No.3 Pages 255 - 257

4. SPring-8通信/SPring-8 COMMUNICATIONS

2012B期 採択長期利用課題の中間評価について
Interim Review Results of 2012B Long-term Proposals

(公財)高輝度光科学研究センター 利用推進部 User Administration Division, JASRI

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- 課題1 -
課題名 Development of spin-resolved Compton scattering in high magnetic fields: probing the orbitals in complex oxides
実験責任者(所属) Jonathan Duffy(University of Warwick)
採択時の課題番号 2012B0045
利用ビームライン BL08W
評価結果 3年目を実施する



The aim of this long-term proposal is to develop a system for magnetic Compton scattering measurements under high magnetic fields at low temperatures, and to unveil magnetic momentum density in complex magnetic compounds by the use of the developed system. The measurement system has been successfully installed by the time of the mid-term review, although there remain two issues for further developments: the operation of superconducting magnet above 7 tesla and the positional stability for specific samples during measurements. In addition, the team has succeeded in finding novel properties in many systems: such as a short correlation length of magnetic wave function in Ca3Co2O6, an unusual electron transfer between orbitals in TbMn2O5, and an itinerant and anisotropic spin density in CeB6 etc. The review committee appreciates the new findings based on magnetic Compton scattering measurements, as well as the development of the measurement system under high magnetic fields up to 7 tesla and at low temperatures down to 1.5 K. The committee, however, has a great concern about no publication at the moment of the mid-term review. The committee concludes that it is appropriate to give another year to this long-term project so that the aim of the project is achieved. In addition, the committee strongly requests the group to publish the papers in high impact journals by accomplishing the theoretical simulation for explaining the novel properties in a year or two to come.



- 課題2 -
課題名 X線分光法による臨界価数ゆらぎによる新しい量子臨界現象の実験的検証
実験責任者(所属) 渡辺 真仁(九州工業大学)
採択時の課題番号 2012B0046
利用ビームライン BL39XU
評価結果 3年目を実施する


 最初に手掛けた成果の一例としては、YbRh2Si2のYb価数の温度・磁場依存性があげられる。ゼロ磁場で低温2 Kのとき価数2.92、200 Kでは2.96、2 Kで30 Tの磁場を印加しても2.93価どまりで、近藤状態の3価には達しないという結果を得ている。この化合物は近藤格子模型ではなく価数搖動状態としてとらえるべきと結論している。この結果はすでに論文発表され、情報発信も適宜行われている。この他、1次の価数転移の量子臨界点と価数クロスオーバーの探索、および価数ゆらぎによる電子状態不安定性の探索をいくつかのYb系化合物について行い、すでに論文投稿予定となっている。
 また、計測技術開発の1つとしてダイヤモンドアンビルセルの開発があげられている。ナノ・ダイヤモンドを用いることにより、グリッチが極めて少なく、結晶を薄くすることにより6 keV以下で従来よりも透過率1桁向上を実現、かつ10 GPa以上の高圧に耐えうる優れたダイヤモンドアンビルセルを開発した。これにより、Ce-L端付近でのX線スペクトルを取得できる実験環境が整えられ、高圧(~ 15 GPa)・低温(~ 3 K)下でのCe系の分光計測が可能になった。


[1] SPring-8 publication ID = 25179
H. Nakai, T. Ebihara, S. Tsutsui, M. Mizumaki, S. Michimura, N. Kawamura, T. Inami, T. Nakamura, A. Kondo, K. Kindo and Y. Matsuda: "Temperature and Magnetic Field Dependent Yb Valence in YbRh2Si2 Observed by X-ray Absorption Spectroscopy" Journal of the Physical Society of Japan 82 (2013) 124712.

[2] SPring-8 publication ID = 25939
S. Watanabe and K. Miyake: "Robustness of Quantum Criticality of Valence Fluctuations" Journal of the Physical Society of Japan 82 (2013) 083704.



- 課題3 -
課題名 Phase Contrast X-ray Imaging of the Lung
実験責任者(所属) Stuart Hooper(Monash University)
採択時の課題番号 2012B0047
利用ビームライン BL20B2
評価結果 3年目を実施する



This long-term project aims at studying lung aeration and related physiological phenomena at birth. In the previous projects, the research group developed imaging techniques that make best use of coherence of the X-ray beam at BL20B2 and applied them to observe lungs in neonates. Since lung aeration at birth is a vital event in life, there are many physiological problems to be tackled. In this long-term proposal so far, the group has made significant progress in (1) optimizing the use of sustained inflations in ventilating preterm neonates, (2) investigating mechanisms for the increase in pulmonary blood flow at birth, (3) optimizing resuscitation and ventilation in neonates with congenital diaphragmatic hernia, (4) optimizing continuous positive airway pressure, and (5) simplifying regional lung air volume calculations using image analysis. The group has published papers that contribute to the advancement in medical imaging and pediatrics.

Although all the experiments scheduled in this project are worthwhile, it would be advised that the group set a clear goal for the research project. The committee suggests the group to somewhat focus the research to maximize the scientific outputs.


[1] SPring-8 publication ID = 25916
S. B. Hooper, M. L. Siew, M. J. Kitchen and A. B. Te Pas: "Establishing Functional Residual Capacity in the Non-breathing Infant" Seminars in Fetal and Neonatal Medicine 18 (2013) 336-343.

[2] SPring-8 publication ID = 25920
A. F. T. Leong, D. M. Paganin, S. B. Hooper, M. L. Siew and M. J. Kitchen: "Measurement of Absolute Regional Lung Air Volumes from Near-Field X-ray Speckles" Optics Express 21 (2013) 27905-27923.

[3] SPring-8 publication ID = 25921
S. B. Hooper, A. Fouras, M. L. Siew, M. J. Wallace, M. J. Kitchen, A. B. Te Pas, C. Klingenberg, R. A. Lewis, P. G. Davis, C. J. Morley and G. M. Schmölzer: "Expired CO2 Levels Indicate Degree of Lung Aeration at Birth" PLoS One 8 (2013) e70895.

[4] SPring-8 publication ID = 25972
R. Carnibella, M. J. Kitchen and A. Fouras: "Decoding the Structure of Granular and Porous Materials from Speckled Phase Contrast X-ray Images" Optics Express 21 (2013) 19153-19162.



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