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EMIN-2012

Development of the polarized Hydrogen- Deuteride (HD) target for d ouble-polarization Experiments at LEPS. . EMIN-2012. RCNP Osaka University . Osaka, Japan Takeshi Ohta. Content. Physics motivation Introduction of HD 1st production in 2009

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EMIN-2012

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  1. Development of thepolarized Hydrogen-Deuteride (HD) target for double-polarization Experiments at LEPS. EMIN-2012 RCNP Osaka University. Osaka, JapanTakeshi Ohta

  2. Content • Physics motivation • Introduction of HD • 1st production in 2009 • Developments (NMR, HD gas analyzer, Distiller) • 3rd production in 2012 • Summary

  3. Introduction Background The hadron photoproduction of the ϕ, K, η, and π0mesons is studied by using linearly polarized photon beams with energies of E γ = 1.5 ∼ 2.9 GeV at SPring-8 (LEPS). These hadron photoproduction experiments have been carried out with unpolarized target.偏極標的があれば、、、 We plan to carry out hadron photoproduction experiments by using polarized photon beams and the polarized target. ObjectiveDevelopment of the polarized Hydrogen-Deuteride (HD) target for double-polarization Experiments at LEPS.

  4. One of the experiments • We plan an experiment with polarized HD targets to investigate the ss content in the nucleon by measuring double polarization asymmetries • in the gp->fp (gn->fn ) reaction EMC (European Muon Collaboration) reported that the contribution of the spin of the quark to that of the proton is very few. SMC (Spin MuonCollabollation) () reported that strangeness quark may be contained 10−20% in the nucleon. HAPPEX Collaboration reported the limitation to the strangeness form factors, and these is nearly zero. Presence of the strange quark content in the nucleon is not conclusive. New data using different reactions play an important role.

  5. γp→fpreaction In the reaction of γp→fp, there are four main reactions as follows Cross Section at Eg = 2.0 GeV Strangeness quark content is assumed to be 0% Pomeron exchange Pomeron exchange uud knockout One pion exchange ss knockout One pion exchange ss knockout It is difficult to evaluate a cross section from ss-bar knockout. Pomeronexchange isdominant uud knockout A.I.Titovet al. Phys. Rev. C58 (1998) 2429

  6. Measurement value CBT(Beam Target asymmetry) Double polarization asymmetry. g (I=1) Nucleon (I=1/2) Beam-Target double spin asymmetry at Eg = 2.0 GeV Strangeness quark content is assumed to be 0% (Solid), 0.25% (Dashed), and 1% (Dot-dashed). A.I.Titovet al. Phys. Rev. C58 (1998) 2429 Beam target asymmetry CBTis very sensitive to the ss-bar content in the nucleon

  7. Other objective Black circle is obtained at SPring-8 at 2004 [T. Mibe, W. C. Chang, T. Nakano et al. Phys. Rev. Lett. 95 182001] Bump structure was found in K+L(1520) gp -> K+L(1520) H. Kohriet al. Phys. Rev. Lett. 104 (2010) 172001 Differential cross sections • Need the polarized nucleon target in advanced studies !! • We have to understand this bump structures to evaluate the CBT exactly.

  8. LEPS Facility Collision a) SPring-8 SR ring 8 GeV electron Recoil electron Electron tagging b) laser hutch Laser light c) experimental hutch Polarization degree of g-ray is 98%(Linearly) and 100%(circualry). Beam energy is 2.4 ~ 3.0 GeV Intensity is ~106g/s Top view of experimental hutch. （set up the experimental refrigerator for HD target）

  9. Introduction of Polarized HD target HD is heteronucleardiatomic molecule consisted by hydrogen and deuteron Polarized method We use the statistical method by cooling down and keeping the HD target at 10 mK with 17 Tesla for a few months (Brute-force method). Advantage and disadvantage Advantage: Dilution factor is good. (the number of H’s / the number of nucleons) HD = 1/3, NH3 = 3/17, C4H10O= 10/74 Disadvantage:The HD target needs thin aluminum wires (at most 20% in weight) to improve the cooling power to solid HD. Size of Target Diameter is 25 mm. Length is 50 mm. Relaxation time Under the condition of the experiment (T=300 mKandB=1 Tesla) , the relaxation time is possible to be longer than several months . 50mm 25mm

  10. Polarization of H and D T : high T : low N- | -1/2> DE=mpB B N+ |+1/2>

  11. Frozen polarization mechanism Initial stageThe polarization of HD is produced by the spin-flip with small concentration of ortho-H2(~0.01%) included in HD at 17 Tesla & T=14 mK After 2, 3 monthsMost of ortho-H2 has converted to para-H2. Polarization degree of HD is kept for about one year at 1 Tesla & T=300 mK ortho para B para B

  12. Frozen polarization mechanizm Concentration of o-H2 Decrease with time. Time constant is 6.5 days Relaxation time Increase with time. The length of relaxation time depends on the concentration of o-H2 Polarization The Polarization grows with time.Growing rate depends on relaxation time.When the relaxation time is very short, the polarization reaches Thermal Equilibrium Initial concentration of o-H2is important for the polarization degree and relaxation time of HD target.

  13. Measurement of NMR spectra Magnetic field ～1.0 Tesla • NMR signalsobtained at 4.2 K as a calibration point after pouring HD gas • (Polarization = 0.024%) • Meas. Environment • Temperature：4.2 K • Magnetic field：1 Tesla • HD target was putted in DR for 53 days with 14 mK and 17 Tesla • Meas. environment • Temperature：300 mK • Magnetic field：1 Tesla Freq. ～42MHz Polarization : 40.8±2.3% Relaxation: 112.8±0.1 days Single coil

  14. Results 1stprodection The temperature of the HD cell might be higher than 14 mK.Theheat transfer is not so good between different material because of the presence of Kapitza resistance at boundries. The linearity between NMR signal height and polarizationSince the magnitude of the signal changes 1000 times, we discuss whether NMR system is linear or not in dynamic range Concentrations of ortho-H2 might be too smallIn this case the relaxation time of H in HD was to bevery long at start time. Polarization did not grow. Why was the polarization low?

  15. Content • Physics motivation • Introduction of HD • 1st production in 2009 • Developments (NMR, HD gas analyzer, Distiller) • 3rd production in 2012 • Summary

  16. Requirement of portable NMR system 1.2 K 1 T 14 mK 17 T 300mK 1 T NMR measurements are required at various points denoted by ○. Portable NMR measurement system has been developed for handy transportation.

  17. ＮＭＲシステムの概要図 Conventional ダイヤグラム図 Portable NMR system ダイヤグラム図 使用したモジュール ・PXI-1036（シャーシ） ・PXI-8360（コントローラ） ・PXI-5404（信号発生器） ・PXI-5142（ADC）

  18. Portable NMR system (PXI-NMR) ロックインアンプ • 重さ、空間スペース、コスト全てにおいてダウン • 手順が簡素化 • 自動調整＆自動測定が可能。 • 測定システムのカスタマイズが可能  • 他人にわかりやすく説明できる W D H 600 600 2000 80 Kg 600万 90%Down 95% Reduce 75% Cut!! 7.1 Kg 150万 W D H 250 200 200 オシロ＆スペアナ ネットワークアナライザ

  19. Comparison of S/N ratio S/N比は従来のNMR測定システムに比べて約半分。 偏極測定での使用は十分と考える 各NMR測定で条件を揃えて測定が可能に！

  20. Requirement of new analayzer for HD Quadrupole mass separatorwas used for analysis of components in the HD gas. HD gas are mass-separated according to the mass/charge ratio (u/e). But this system have a problem. Fragmentation problem When HD gas is ionized, H+ and D+ions is produced by electron bombarded. Fragmentation factor D+/HD = 0.4% H2+/HD ~0.001% <= We want to measure!! New analyzer is required avoiding the problemfor analysis of HD gas precisely

  21. New gas analyzer GC-QMS (Gas Chromatograph and Quadrupole Mass Spectrometer) distiller Components in the HD gas are separated by using the difference of retention time in the column and the mass/charge ratio measured by the QMS. The column is cooled down to about 110 K. ////to attain a reasonably long retention time for the hydrogen and deuterium gases. 軽い粒子は早く、思い粒子は遅い　通過時間の差でわける HDをパルス的に入れる。

  22. Result of GC-QMS p-H2, o-H2, HD, and D2components is separated by elapsed time in the GC completely. The measurement is possible with 0.001% precision for the components. p-H2 and o-H2is separated. テーブルを作る New analyzer for HD gas is developed and fragmentation problem is avoided

  23. 蒸留塔１号機と２号機 写真 外観図 充填物

  24. New distiller Distiller is designed basis on chemical industries. NTS is designed 37.9 Simulate from design of new distillator H2 HD D2

  25. Distillation process with new distiller Commercial HD gas 蒸留器Topと蒸留器Bottomの成分組成から、新蒸留器の性能を示す指数理論段数は 37.2 ± 0.6 ※設計値は37.9 と得られた。 Before distillation After distillation

  26. Old vs. New distiller New distiller Old distiller 設計値通りの新蒸留器 ２号機が完成。o-H2, p-D2の濃度操作には必要十分

  27. New HDdistiller and new gas analyzer • The new analysis system enabled us to observe p-H2, o-H2, HD, and D2separately. • Components in HD gas enable us to analyze with a high precision of 0.001% • Distillation term is shorten from 34 days to less than 6 days We can control the concentration of o-H2 andD2 when HD target is produced. New HD distiller and new gas analyzer enable to us to optimize aging time. (In my calculation, the aging time is able to shorten to ~2 weeks) T. Ohtaet al. NIM-A 664 (2012) 347 T. Ohtaet al. NIM-A 640 (2011) 241

  28. 3rd production HD gas for target was produced Distiller and analyzed. Concentration of o-H2 in prepared HD gas for the target is 2x10-4%. NMR signal obtained after pouring HD gas at 500 mK. Polarization calculated from Boltzmann low is 0.2% at 500 mK NMR signal obtained after 2 month of aging time. Polarization : 30% Relaxation: 40~100 days *Preliminary Conclusion : 2x10-4% is too low for production of HD target.

  29. HD single crystal HD target includes the aluminum wires of 20% in weight. HD single crystal a hexagonal single crystal and have a good thermal conductivity of HD target. The thermal conductivity of normal HD target is < 0.1 W/Km kL: perpendicular k|| : parallel Pour the HD gas K|| kL In the future, we will replace the HD single crystal from normal HD target included aluminum wires

  30. Summary We have been developing for the complete double polarization experiment to investigate strangeness quark contents of the nucleon. We tried the 1st production of the HD target in 2009. The polarization was 41.4% and relaxation time was 106 days. We can measure the NMR signal anywhere. We can control the concentration of o-H2 andD2 in the HD gas by new gas analyzer and new distiller. We tried the 2nd production of the HD target in 2012. The polarization was 30% and relaxation time was 100 days. • Future plan • Transporting the polarized HD target from RCNP to SPring-8 • Startingf-meson experimentusing the polarized HD target.

  31. Backup

  32. New data for strangeness in the nucleon Recently, HAPPEX Collaboration reported new data!! Achaet al. Phys. Rev. Lett. 98 032301 (2007) [18] N.W. Park and H. Weigel, Nucl. Phys. A541, 453(1992). [19] H.W. Hammer, U.G. Meissner, and D. Drechsel, Phys.Lett. B 367, 323 (1996). [20] H.W. Hammer and M. J. Ramsey-Musolf, Phys. Rev. C 60, 045204 (1999). [21] A. Silva et al., Phys. Rev. D 65, 014016 (2001). [22] R. Lewis et al., Phys. Rev. D 67, 013003 (2003). [23] D. B. Leinweber et al., Phys. Rev. Lett. 94, 212001 (2005);97, 022001 (2006). Presence of the strange quark content in the nucleon is not conclusive. New data using different reactions play an important role. We plan to measure the double polarization asymmetry for the gp->fp (gn->fn ) reaction

  33. 16 observables for the gp KY reaction ObservablePolarization BeamTargetHyperon Single polarization & Cross section ds/dW- - - Slinear- - T- transverse- P- - y Beam-Target doublepolarization G linear z - H linear x - E circular z - F circular x - Beam and Recoil hyperon double polarization Ox linear - x Oz linear - z Cx circular - x Cz circular - z Target and Recoil hyperon double polarization Tx - xx Tz - x z Lx - z x Lz - z z Many groups LEPS CLAS and SAPHIR measured forK+Land K+S0 Recently CLAS measured forK+LandK+S0 フォトン偏極は直線と円 標的偏極は Longitudinal と　Transverse

  34. gp->phi p cross sections この角度とエネルギーを避けてデータ解析する

  35. Pentaquark (q+uudds) search Although the results are positive, statistics is not enough in both data. We took data with 3 times higher statistics than Data (2) in 2006-2007. Data analysis is underway now. New data will appear soon. T. Nakano et al. PRL 91 (2003) 012002 T.Nakano et al. PRC 79 (2009) 252 (1) gC reaction (2) gd reaction Counts Counts Mass (GeV/c2) Mass (GeV/c2)

  36. BNL-E949 spectrometer was transported to SPring-8 来年メイン検出器TPCがインストールされる @SPring-8 LEPS2 experiment hutch

  37. Collaborators of HD project K. Fukuda, M. Fujiwara, T. Hotta, H. Kohri, T. Kunimatsu, C. Morisaki, T. Ohta, K. Ueda, M. Uraki, M. Utsuro, M. Yosoi, (RCNP, Osaka) S. Bouchigny, J.P. Didelez, G. Rouille (IN2P3, Orsay, France) M. Tanaka (Kobe Tokiwa University, Japan) Su-Yin Wang (Institute of Physics, Academia Sinica, Taiwan)

  38. 核子内のストレンジネスの探索 肯定的結果　 偏極ミューオン,偏極陽子深部非弾性散乱 (EMC)J. Ashman et al., Nuclear Physics B 328 (1989) 1. ・・核子のスピンを構成するものとしてssがu,dクォークに匹敵する 否定的結果　 電子陽子弾性散乱　パリティの破れ　(HAPPEX)A. Acha et al., Phys. Rev. Lett. 98, (2007) 032301. ・・電子陽子弾性散乱ではストレンジネスのGE、GMは0に近い 偏極標的を使用した最初の実験として核子からssを叩き出す実験を計画している γp→φp反応

  39. Future plan

  40. After aging HD target, condition is changed The temperature and magnetic field are different on the production and experiment Low magnetic field and high temperature may decay the polarization of HD. Magnetic field to polarized HD Temperature of polarized HD Temperature must be increased. Magnetic field must be decreased. Aging B=17 Tesla TC1 TC2 Temperature (K) Magnetic Field (Tesla) Experiment at SPring-8 B=1 Tesla Experiment at SPring-8 T=300 mK In truck B=1 Tesla In truck T=1.2 K Aging T=14 mK TC1 TC2 Time (hour) Time (hour)

  41. 偏極度とAgingtimeの関係 　~モデル式~ Fig. A T1 Aging time Fig. B P Aging time

  42. 問題点を羅列 First productionをやったけれども

  43. Simulate!! • Ortho-H2 is,,,,,, • Too poor normal too many

  44. mD=-1 mD=-1 mD=-1 mD=-1 mD=0 mD=+1 mD=0 mD=0 mD=0 mD=+1 mD=+1 mD=+1 mH=-1/2 mH=-1/2 mH=-1/2 mH=-1/2 mD=-1 mD=0 mD=+1 mH=-1/2 mH=+1/2 mH=+1/2 mH=+1/2 mH=+1/2 mH=+1/2 mD=-1 mD=0 mD=+1 mH=-1/2 mH=+1/2 FAFP (Transfer polarization from H to D) First transition Second transition Init PD=0 PD=0.33 RF in PD=0.33 PD=0.58 Nature decay

  45. Saturated forbidden transition (SFT) • This method uses frequency modulated RF to produce a rapid succession of low efficiency spin transfers by passing through the resonance many times. • The D polarization can reach 31.1%. M. Bade PHD thesis 2006

  46. Expected Polarization loss during transportation of HD from RCNP to SPring-8 Initial polarization is assumed to be 100% as a result…… In Beam Cryostat (IBC) Experiment@300mK H : T1= 106±16 days Storage Cryostat (SC) Transportation@1.2K H : T1= 11.6±1.5 days Transfer Cryostat (TC1,TC2) Transpotation@4.2K H : T1= 7.5±0.7 days

  47. Chapter 4 ｜偏極度と緩和時間の考察 • 緩和時間について • アメリカのLEGSグループとの比較。緩和時間はLEGSが達成していた≧1 yearよりも短かった。エイジング期間はLEGSよりも短い53日 偏極度について・・・ 偏極度を精度よく求めるためには4.2 KでのNMR強度の精度が重要NMRのベースラインが不安定であったり、水素のバックグラウンドを含んでいるためにNMRの強度を精度よく評価出来ない 偏極度が期待されたもの（84%）より低かったことについて NMR測定本質における線形性が崩れている可能性 o-H2の量が最適ではなかった希釈冷凍機投入前にHDガスは蒸留器内で３４日間蒸留されていた。その間o-H2 がほとんどp-H2に転換していた可能性がある。o-H2を測定できる技術はなかった。

  48. PXI-NMR｜水素バックグラウンドの除去 NMRを測定したときに検出されるHD以外からの水素のNMR共鳴は偏極度を決定する際に不確かさの原因となる。水素のバックグラウンドの起因を突き止め除去した。 HD有り。1.14mol入れた時 HD無し。Hの量は0.06mol以下

  49. PXI-NMR｜ベースラインのドリフトを改善 NMR測定時にベースラインがドリフトし、解析に影響した。 ベースラインが安定するよう回路の温調（40℃）を試みた (a) 温調なし (b) 温調箱を閉め恒温状態 (c)温調箱を閉めて温調する S/N比は約10倍に向上した。

  50. PXI-NMR｜まとめ • 温調によりS/N比を10倍にした • エナメル線のコイルをテフロン銀線に交換することにより水素の強烈なバックグラウンドを取り除いた • ポータブルNMR測定システムで至る所でNMR測定が可能になり、また測定条件を揃えることが可能になった 2011年2月にパブリッシュ T. Ohtaet al. NIM-A 633 (2011) 46

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