1 / 31

Takeshi Furukawa

International Nuclear Physics Conference 2007 - Jun. 4 -. Hyperfine structure of 85,87 Rb and 133 Cs atoms in superfluid helium. Development of new laser spectroscopy project using superfluid helium stopper. Takeshi Furukawa. Nishina-Center, RIKEN. Collaborator.

rane
Télécharger la présentation

Takeshi Furukawa

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. International Nuclear Physics Conference 2007 - Jun. 4 - Hyperfine structure of 85,87Rb and 133Cs atoms in superfluid helium Development of new laser spectroscopy project using superfluid helium stopper Takeshi Furukawa Nishina-Center, RIKEN Collaborator Y. Matsuo1, A. Hatakeyama2, T. Ito3, K. Fujikake3 T. Kobayashi1, and T. Shimoda4 1Nishina-Center, RIKEN, 2Dept. Appl. Phys., Tokyo Univ. of Agr. Tech., 3Dept. Phys., Meiji Univ. 4Dept. Phys., Osaka Univ.

  2. Contents International Nuclear Physics Conference 2007 - Jun. 4 - 1) Our New laser spectroscopy project ・Double resonance method in He II ( Laser spectroscopy & optical detection Optical pumping in He II 2) Measurement data in the development ・Long atomic spin relaxation time in He II ・hyperfine resonance spectrum of 85,87Rb and 133Cs in He II ・determination of nuclear magnetic dipole moment ・hyperfine anomaly in He II 3) Summary and future prospect

  3. Overview of Our Method from “DRAEMON” vol. 22, by FUJIKO, F. Fujio International Nuclear Physics Conference 2007 - Jun. 4 - Development : laser spectroscopy for short-lived RI atoms OROCHI project (tentative) Optical RI-atom Observation in Condensed Helium He II liquid RI atom purpose Systematical measurement of unknown hyperfine structures in exotic RI atoms Laser RI beam Laser induced fluorescence (LIF) effective stopping & trapping of RI atoms wavelength separator & photon detector using superfluid helium as a stopper & trap

  4. Nuclear Laser Spectroscopy Contaminated atoms: no absorbing laser light →observe only objective atoms !! absorb & emit photons cyclically → detect much photons/atom (typically ~ 105-108 photons /sec) →good statistic !! absorption spectra in He II : largelybroadened & blue-shifted. wavelength : λatoms≠ λlaser suppress the detection of scattered laser light feasible to achieve optical pumping of various atomic species i.e.) In, Tl, …. International Nuclear Physics Conference 2007 - Jun. 4 - Laser induced fluorescence (LIF) photon He II Laser Scattered laser photon RI beam

  5. Double Resonance Method expected spectrum LIF intensity microwave frequency International Nuclear Physics Conference 2007 - Jun. 4 - Purpose: measure the hyperfine structure of RI atom Polarized atoms : Can not absorb circularly polarized laser light. LIF Intensity ∝ 1 - Pz

  6. Spin relaxation inHe II extremely longer than optical pumping time International Nuclear Physics Conference 2007 - Jun. 4 - To polarize the atoms : spin relaxation time is important long spin relaxation time in He II has been measured. feasible to achieve optical pumping 133Cs atoms in He II T. Furukawa et al., Phys. Rev. Lett. 96, 095301 (2006)

  7. Experimental Setup International Nuclear Physics Conference 2007 - Jun. 4 - Measurement of the hyperfine splitting in Cs, Rb atoms CsI Cs Cs

  8. Double resonance peak inHe II International Nuclear Physics Conference 2007 - Jun. 4 - Hyperfine resonance measurement ：stable 133Cs, 85,87Rb measured spectrum using double resonance method ν133Cs= 9.2580915 (4) GHz ν87Rb= 6.87652 (10) GHz ν85Rb= 3.05802 (10) GHz A85Rb = 1.01702(2) GHz A87Rb = 3.43517(4) GHz （Preliminary） A133Cs = 2.312 76(2) GHz （Preliminary） （Preliminary）

  9. Hyperfine Structure inHe II Pressurized by helium H’ (> H) International Nuclear Physics Conference 2007 - Jun. 4 - H Calcuration from hyperfine coupling constant In He II electron nuclei Enable to obtain the nuclear information efficiently!!

  10. for RI Beam Experiment Wavelength plate Wavelength plate Lens Laser Induced Fluorescence 　　（LIF） Optical filter Lens International Nuclear Physics Conference 2007 - Jun. 4 - to confirm the feasibility of our project measure the LIF photons from RI atoms estimated lower limit of the beam intensity to measure：only 10 cps

  11. Conclusion International Nuclear Physics Conference 2007 - Jun. 4 - We are now developing successfully… OROCHI project (tentative) Optical RI-atom Observation in Condensed Helium measure the hyperfine structure of exotic RI atoms 133Cs, 85,87Rb hyperfine splitting in He II ・deduce nuclear moment with 1% accuracy ・deduce hyperfine anomaly with 5% accuracy * Nuclear spin can be also determined with rf-resonance ~Next plan~ + RI beam experiment (plan: in next year) + Optical pumping of various elements (In, Tl, Ca, ….) Goal : measurement of In, Tl isotopes

  12. ふろく International Nuclear Physics Conference 2007 - Jun. 4 - Additional OHP

  13. Zeeman sublevels of 85,87Rb 高さの比 ＝6636/22370 ＝0.297 同位体比＝27.85/72.15 = 0.386 →ｒｆパワーが違うため？ 周波数比 ＝1815/2720　≒ 2/3 理論比　＝ gF=3/gF=2 ≒ 2/3 →未知の核種の核スピン同定が可能！ 85Rb 87Rb

  14. Pressure effect inHeII Pressurized by helium H H’ (> H) Hyperfine coupling constant ＜ 1% increase HeII (GHz) HeII/vacuum ratio vacuum (GHz) 133Cs 1.00635(1) 2.31276(2) 2.29815794 ΔCs＞ΔRb 1.00505(2) 1.01191092 1.01702(2) 85 Rb 87 1.00522(1) 3.43517(4) 3.41734131 A=mI<H>/I・J Difference of <H> in He II Compressed atom by surrounding helium Affect to the orbital of valence eveltrons VCs＞VRb

  15. Determination of 85Rb moment Deduce 85Rb moment with 87Rb moment as reference Use A value in vacuum: literature value： ・possible to determine the moment with 1% accuracy ・difference (～0.3%) ← caused by hyperfine anomaly electron Effect of the distribution of nuclear magnetization nuclei

  16. Hyperfine anomaly inHe II Considering hyperfine anomaly… hyperfine anomaly In HeII ) ～５％ difference In vacuum In HeII In vacuum Due to the deformed electron distribution by the pressure of surrounding He ??

  17. Hyperfine Interaction Hyperfine Interaction W(F, mF)= A・K/2 + B・{3K(K+1)/4 –I(I+1)J(J+1)}/{2(2I-1)(2J-1)IJ} [K=F(F+1)-I(I+1)-J(J+1)] A=m<B>/IJ B=eQ<V> I:nuclear spin, J:electronic angular momentum, m: nuclear magnetic dipole moment, eQ: nuclear electric quadrupole moment, <B>:magnetic field produced by the electrons <V>:electric field gradient produced by the electros Measure the constant A, B of isotope mX and nX mmX eQmX AmX ImX BmX = = mnX AnX InX eQnX BnX

  18. Effect of surrounding He atoms Bubble model Deform Energy absorption emission absorption emission Deform Bubble radius Energy levels in the ground state and excited state as a function of bubble radius. ① Blue-Shifted ( absorption spectrum in He II ② Broadened

  19. Excitation Spectrum in He II ① Blue-Shifted ( ( absorption spectrum in He II ② Broadened by the pressure of surrounding He atoms 133Cs atomic spectra in He II emission：peak ~892 nm, width ~3 nm (in vacuum: 894.347nm) Intensity (arb.unit) absorption：peak ~876 nm, width ~15 nm absorption≠emission Wavelength (nm)

  20. Optical Merit in HeII ① Blue-Shifted ( ( absorption spectrum in He II ② Broadened In vacuum In He II Laser Excitation with only single laser light Need many laser lights! Detector wavelength:lLIF≠ llaser suppress the detection of scattered laser light Feasible to acheve optical pumping

  21. Optical Pumping P1/2 σ+ σ+ P1/2 D1 Line X σ+ σ+ D1 Line S1/2 X m = -1/2 m = +1/2 S1/2 m = -1/2 m = +1/2 Optical pumping method atom laser （in the case of alkali atoms J=1/2） B After the polarizing of atoms… Decrease LIF intensity (Laser Induced Fluorescence, LIF) LIF Intensity ∝ 1 - Pz

  22. Optical Pumping of Metastable Mg atoms 21 Mg atomic energy diagram Observable resonance line (Assume I = 5/2 ) 3 3s3p P F=9/2 ⇔ F=7/2 2 [h.f.s = (9/2)A + (27/40)B] F=7/2 ⇔ F=5/2 [h.f.s = (7/2)A + (7/40) B] 3 ( 3s3p P F=7/2 ⇔ F=5/2 ) 1

  23. Optical Pumping of Al atoms 問題点：基底状態(3s23p 2P1/2,3/2)の偏極緩和時間 2P3/2：電子軌道が非対称→緩和しやすい 2P1/2：電子軌道が球対称→緩和しにくい →2P1/2では偏極生成可能？ 27Alの原子準位図 3s23p 2P1/2,3/2 ⇔ 3s24s 2S1/2 transition ・3s23p 2P1/2,3/2,mF>+3の準位 →円偏光(σ+)を吸収不可能 特定の磁気状態に原子状態が集中 　 ＝ 偏極生成可能！！

  24. Relaxation in the Dark Method Measure the relaxation time →“Relaxation in the dark” method detect the photons only from the “spin relaxed” atoms

  25. Timing chart

  26. Spin relaxation time in He II Dark period後のLIF強度 偏極ゼロ時のLIF強度

  27. Measured LIF intensity

  28. Demerits in Optical Detection Introduced to condenced helium → observe all of the stopped atoms Using the characteristic spectrum of atoms in He II high trapping efficiency →Subtract the problems Laser Stopped & trapped Interaction with surrounding He RI Beam Problems in laser spectroscopic study of RI atoms ・possible elements ・stopping & Trapping efficiency B.G. count of stray light In He II・・・

  29. Scientific Motivation Laser spectroscopy & optical detection of RI atoms ) Optical pumping in He II ex) b-NMR method Measure the hyperfine structure detector stopper Polarized RI nucleus Determination of nuclear moments detector Signals from RI Unstable nuclei near the drip-line ・low-yield ・high-contamination ・small-polarization Difficult to measure !!!!

  30. Scientific Motivation 目標：短寿命不安定核の系統的核モーメント測定法開発 Nuclear moments Nuclear structure however… Unstale nuclei near the drip-line ex) b-NMR method ・low yield detector ・low purity stopper Polarized RI nucleus ・small polarization detector Difficult to measure!! Signals from RI そこで… 『Laser spectroscopy of stopped RI atoms in HeII』 に着目

  31. Conclusion 超流動ヘリウム中でのレーザー・マイクロ波二重共鳴法 安定核133Cs, 85,87Rbの超微細構造を測定 ・核モーメントを１％以下の精度で決定可能 RF共鳴を用いれば核スピンも決定可能 理論的には電気四重極モーメントも同時に測定可能 ・hyperfine anomaly効果も数％の精度で決定可能 真空中の値と～５％のズレ 　　　　　→ 核内核子の密度分布に対する新しい情報？ ～Next Plan～ ・HeIIの影響について考察 ・不安定核ビームを用いた測定 ・Al, Mg原子の光ポンピング

More Related