EMIN-2012

RCNP Osaka University.Osaka, JapanTakeshi Ohta

Development of thepolarized Hydrogen-Deuteride (HD) target for double-polarization Experiments at LEPS.

Content

Physics motivation

Introduction of HD

1st production in 2009

Developments (NMR, HD gas analyzer, Distiller)

3rd production in 2012

Summary

BackgroundThe hadron photoproduction of the ϕ, K, η, and π0 mesons 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.

Introduction

ObjectiveDevelopment of the polarized Hydrogen-Deuteride (HD) target for double-polarization Experiments at LEPS.

One of the experimentsWe plan an experiment with polarized HD targets to investigate the ss content in the nucleon by measuring double polarization asymmetriesin 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 Muon Collabollation) () 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.

Pomeron exchange

One pion exchange

ss knockout

uud knockout

A.I.Titov et al. Phys. Rev. C58 (1998) 2429

In the reaction of γp→fp , there are four main reactions as follows

γp→fp reaction

Pomeron exchange

One pion exchange

ss knockout

uud knockout

It is difficult to evaluate a cross section from ss-bar knockout. Pomeron exchange is dominant

Cross Section at Eg = 2.0 GeVStrangeness quark content is assumed to be 0%

Measurement value CBT (Beam Target asymmetry)

g (I=1)Nucleon (I=1/2)

Double polarization asymmetry.

Beam-Target double spin asymmetryat Eg = 2.0 GeV

Strangeness quark content is assumed to be 0% (Solid), 0.25% (Dashed), and 1% (Dot-dashed). A.I.Titov et al. Phys. Rev. C58 (1998) 2429

Beam target asymmetry CBT is very sensitive to the ss-bar content in the nucleon

Other objective

Need the polarized nucleon target in advanced studies !!We have to understand this bump structures to evaluate the CBT exactly.

Black circle is obtained at SPring-8 at 2004 [T. Mibe, W. C. Chang, T. Nakano et al. Phys. Rev. Lett. 95 182001]

Differential cross sectionsH. Kohri et al. Phys. Rev. Lett. 104 (2010) 172001

Bump structure was found in K+L(1520)gp -> K+L(1520)

b) laser hutch

a) SPring-8 SR ring

c) experimental hutch

Laser light

8 GeV electron

Recoil electron

Electron tagging

Collision

Polarization degree of g-ray is 98%(Linearly) and 100%(circualry).Beam energy is 2.4 ~ 3.0 GeVIntensity is ~106 g/s

LEPS Facility

Top view of experimental hutch. 　（ set up the experimental refrigerator for HD target ）

Introduction of Polarized HD target

Polarized methodWe 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 disadvantageAdvantage: Dilution factor is good. (the number of H’s / the number of nucleons) HD = 1/3, NH3 = 3/17, C4H10O = 10/74Disadvantage: The HD target needs thin aluminum wires (at most 20% in weight) to improve the cooling power to solid HD. Size of TargetDiameter is 25 mm. Length is 50 mm.

Relaxation timeUnder the condition of the experiment (T=300 mK 　 and 　 B=1 Tesla) , the relaxation time is possible to be longer than several months .

50mm

25mm

HD is heteronuclear diatomic molecule consisted by hydrogen and deuteron

Polarization of H and D

)2

(tanh3

)2

tanh(4

)tanh(

20

kTE

kTE

NNNNN

P

kTE

NNNN

P

vD

H

-

-

-

-

-

-

| -1/2>

|+1/2>

E=mpB

N-

N+B

T : high T : low

Hydrogen Deuteron

17 T 10 mK 94.0% 31.9%14 mK 84.5% 23.6%

1 T 4.2K 0.024% 0.0050%

Frozen polarization mechanism

ortho

para

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

Bpara B

Frozen polarization mechanizm

PolarizationThe Polarization grows with time. Growing rate depends on relaxation time.When the relaxation time is very short, the polarization reaches Thermal Equilibrium

Relaxation timeIncrease with time. The length of relaxation time depends on the concentration of o-H2

Initial concentration of o-H2 is important for the polarization degree and relaxation time of HD target.

Concentration of o-H2

Decrease with time. Time constant is 6.5 days

Measurement of NMR spectra

NMR signals obtained 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

Single coil

Magnetic field

～ 1.0 Tesla

Polarization : 40.8±2.3%Relaxation : 112.8±0.1 days

Results 1st prodection

The temperature of the HD cell might be higher than 14 mK. The heat 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 be very long at start time. Polarization did not grow.

Why was the polarization low?

17 Tesla &14 mK polarization Relaxation timeExpected 84.5% 3 month ?

measured 41.4% +/-3.1% 106+/-16 days

Content

Physics motivation

Introduction of HD

1st production in 2009

Developments (NMR, HD gas analyzer, Distiller)

3rd production in 2012

Summary

Requirement of portable NMR system

14 mK17 T

1.2 K1 T

300mK 1 T

NMR measurements are required at various points denoted by ○.Portable NMR measurement system has been developed for handy transportation.

ＮＭＲシステムの概要図

使用している機器

・信号発生器

・ロックインアンプ

・オシロスコープ

・ネットワークアナライザ

・フィルタ

・マルチメーター

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 ）

ダイヤグラム図Portable NMR system

Conventional ダイヤグラム図

Portable NMR system (PXI-NMR)

ネットワークアナライザ

オシロ＆スペアナ

ロックインアンプ

600 万 80 Kg

7.1 Kg 150 万

75%Cut!!

95%Reduc

e

6006002000

WDH

90%Dow

n250200200

WDH

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

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！

Fragmentation factorD+/HD = 0.4%H2

+/HD ~0.001% <= We want to measure!!

Fragmentation problemWhen HD gas is ionized, H+ and D+ ions is produced by electron bombarded.

Quadrupole mass separator was 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.

New analyzer is required avoiding the problem for analysis of HD gas precisely

Requirement of new analayzer for HD

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。

GC-QMS (Gas Chromatograph and Quadrupole Mass Spectrometer)

distiller

New gas analyzer

Result of GC-QMS

p-H2 , o-H2 , HD, and D2 components is separated by elapsed time in the GC completely.The measurement is possible with 0.001% precision for the components.p-H2 and o-H2 is separated. テーブルを作る

New analyzer for HD gas is developed and fragmentation problem is avoided

蒸留塔１号機と２号機写真 外観図 充填物

New distiller

Distiller is designed basis on chemical industries. NTS is designed 37.9 Simulate from design of new distillator H2

D2

HD

Distillation process with new distiller 　Commercial HD gas

Before distillation After distillation

11/21 11/25 11/29 12/3 12/71.0E-03

1.0E-02

1.0E-01

1.0E+00

1.0E+01

1.0E+02Erapse time vs Concentration

H2 top [%]D2 top [%]

Elapsed time

Conc

entr

ation

[%]

Old vs. New distiller

Run 3 H2 HD D2

Initial 99.963% 0.035% 0.002%

Distilled ~0.001% ~99.999% ~0.001%

Term 6 days (not need removing D2)

NTS 37.2 ± 0.6 　 (Designed 37.9)

H2 HD D2

Initial 75.00% 24.96% 0.03%

Distilled 0.03% 97.71% 2.26%

Term20 days for removing H2 14 days for removing D2

NTS 14

Old distiller New distiller

New HD distiller and new gas analyzer

T. Ohta et al. NIM-A 640 (2011) 241 T. Ohta et al. NIM-A 664 (2012) 347

The new analysis system enabled us to observe p-H2 , o-H2 , HD, and D2 separately.

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 and D2 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)

3rd production

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

HD gas for target was produced Distiller and analyzed. Concentration of o-H2 in prepared HD gas for the target is 2x10-4%.

Conclusion : 2x10-4% is too low for production of HD target.

HD single crystal

Pour the HD gas

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

K||

kL : perpendiculark|| : parallel

In the future, we will replace the HD single crystal from normal HD target included aluminum wires

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 and D2 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 Starting f-meson experiment using the polarized HD target.

Backup

New data for strangeness in the nucleon

Acha et 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).

Recently, HAPPEX Collaboration reported new data!!

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

16 observables for the gp KY reaction

Observable Polarization Beam Target Hyperon Single polarization & Cross section ds/dW 　 - 　 　 - 　 　　 - S 　 linear 　 　 - 　 　　 - T 　 　 - transverse 　 　　 - P 　　 - 　 　 - 　　 y

Beam-Target double 　 polarization 　 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 - x x Tz - x z Lx - z x Lz - z z

Recently CLAS measured for K+L and K+S0

CLAS and SAPHIRmeasured for K+L and K+S0

LEPSMany groups

フォトン偏極は直線と円標的偏極は Longitudinalと　 Transverse

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

Cou

nts

Mass (GeV/c2)

Cou

nts

Mass (GeV/c2)

(1) (2)

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

Pentaquark (q+ uudds ) search

gC reaction gd reaction

BNL-E949 spectrometer was transported to SPring-8

@SPring-8 LEPS2 experiment hutch

来年メイン検出器 TPC がインストールされる

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)

Collaborators of HD project

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

Future plan

After aging HD target, condition is changed

Time (hour) Time (hour)

Magnetic field to polarized HD Temperature of polarized HD

AgingB=17 Tesla

AgingT=14 mK

Experiment at SPring-8B=1 Tesla

Experiment at SPring-8T=300 mK

In truckB=1 Tesla In truck

T=1.2 K

TC1

TC1

TC2

TC2

Mag

netic

Fie

ld (T

esla

)

Tem

pera

ture

(K)

Magnetic field must be decreased.

Temperature must be increased.

The temperature and magnetic field are different on the production and experiment Low magnetic field and high temperature may decay the polarization of HD.

にプロットする。　 　 　 　 　 　 この式を

日の場合転換時間

る。の式は以下のようにな結果偏極度の時間依存

　 　 　 　 　 両辺を積分

に式（２）を代入して　 　 　

の逆数なのでは　 　 　 　

として極する数をそこで単位時間内に偏み立てる必要がある。微分方程式から式を組存している場合は合の式であり時間に依が時間に依存しない場式であるが、これはここで

・・・・・（２）

にプロットするうこと。この式をが時間に依存するといここで言いたいのはる。の増大も非常に速くな速いとこの転換時間が非常に

。に転換する時間であるからはは初期の緩和時間、る。は以下の式であらわせ場合長くなっていく。この

てに転換することによっがは標的の場合、しかし偏極

・・・・・（１）わされる。に依存し次の式であら時間その場合偏極度は緩和

減衰する。上昇する場合、偏極がころから高いところへ偏極度は温度が低いと

Fig.B)1)5.6/(exp(6.5exp1

6.5

)1)/(exp(exp1

))/exp(exp()(1

)/exp())(1log(

)/exp()(1

T1/1)(1

T1)(1

))(1(

/T1)1(

)/exp(

Fig.AT1T1

H2-paraH2-orthoT1

H2-paraH2-orthoT1HD

)/exp(T1

0

0

0

0

0

1

001

0

1

2

----

----

---

-

---

-

-

-

-

-

-

-

-

tT

P

T

TtT

TP

CTtT

TtP

CT

TtTtP

dtT

TttP

dP

dtTtP

dP

dttP

dP

tPdtdP

dtdp

TtT

NT

T

TT

TtPP

conv

convconv

convconv

convconv

conv

convHortho

conv

TE

偏極度と Aging 　 time の関係 　 ~ モデル式 ~ Fig. A

Fig. B

T1

Aging time

Aging time

P

問題点を羅列First production をやったけれども

Simulate!!

• Ortho-H2 is,,,,,,• Too poor normal too many

----

-

--

-

--

-

-

-

-

-

-

-

-

)1)/(exp()(1exp1

))/exp()(1exp()(1

)/exp()(1))(1log(

)/exp()()(1

/1)(1

)(1

))(1(

)/exp()(

...)/exp(

0

0

0

0

1

001

1

2

convconv

conv

conv

conv

conv

conv

convHortho

TE

TtTTZ

TP

CT

TtTZT

tP

CT

TtTZT

tP

dtT

TtTZtP

dP

dtTtP

dP

dttP

dP

tPdtdP

TtTZT

NTT

butTtPP

Init

RF in

Naturedecay

First transition Second transitionmD=-1 mD=0 mD=+1

mH=+1/2

mH=-1/2

mD=-1 mD=0 mD=+1

mH=+1/2

mH=-1/2

mD=-1 mD=0 mD=+1

mH=+1/2

mH=-1/2

mD=-1 mD=0 mD=+1

mH=+1/2

mH=-1/2

mD=-1 mD=0 mD=+1

mH=+1/2

mH=-1/2

mD=-1 mD=0 mD=+1

mH=+1/2

mH=-1/2

PD=0

PD=0.33

PD=0.33

PD=0.58

FAFP (Transfer polarization from H to D)

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

Initial polarizationis assumed to be 100%

Expected Polarization loss during transportation of HD from RCNP to SPring-8

as a result……In Beam Cryostat (IBC) Experiment@300mKH : T1= 106±16 days

Storage Cryostat (SC) Transportation@1.2KH : T1= 11.6±1.5 days

Transfer Cryostat (TC1,TC2) Transpotation@4.2KH : T1= 7.5±0.7 days

Chapter 4 ｜偏極度と緩和時間の考察

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。

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

RCNP (2009) LEGS (2007)

偏極度 40.8± 2.3 % ~60%

緩和時間 112.8±0.1 days ≧1 year

Aiging time 53 days 3 month

PXI-NMR｜水素バックグラウンドの除去

HD無し。 H の量は 0.06mol以下

HD有り。 1.14mol 入れた時

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。

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。

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. Ohta et al. NIM-A 633 (2011) 46

• EMIN-2012 は物理の話をするところ

• 時間３０分（トーク２０分　質疑１０分）• タイトルDevelopment of the Polarized Hydrogen-Deuteride (HD) Target for Double- Polarization Experiments at LEPS.

物理と開発系の話のバランスが難しい。

BACKUP

蒸留塔第１号機

H2

HD

D2

Extraction

HD

D2

Extraction

STEDMANPACKING

HD

市販ＨＤガス（ H2 　 3% :D2 　 3% ）を投入

H2 HD D2

蒸留直後 75.00% 24.96% 0.03%

蒸留後 0.03% 97.71% 2.26%

11/19 11/2111/23 11/25 11/27 11/29 12/1 12/3 12/5 12/71.0E-03

1.0E-02

1.0E-01

1.0E+00

1.0E+01

1.0E+02Erapse time vs Concentration

H2 top [%]

D2 top [%]

TIME

Conc

entr

ation

1[%

]

温度及び n-H2 の濃度緩和時間の関係

Walter N. Hardy Phys. Rev. Lett. 17 (1966) 1258

4.2K での o-H2及び p-D2 と H及びD の緩和時間

LEPS experiment in the past.(A) f meson photoproduction f meson production on Li, C, Al, Cu T. Ishikawa et al. Phys. Lett. B 608 (2005) 215 *gp -> fp T. Mibe et al. Phys. Rev. Lett. 95 (2005) 182001 gd -> fd W.C. Chang et al. Phys. Lett. B 658 (2008)

209 gn -> fn W.C. Chang et al. Phys. Lett. B 684 (2010) 6 gp -> fp, gn -> fn W.C. Chang et al. Phys Rev. C 82 (2010) 015205

(B) Strangeness photoproduction gp -> K+L, gp -> K+S0 R.G.T. Zegers et al. Phys. Rev. Lett. 91 (2003) 092001 gp -> K+L, gp -> K+S0 M. Sumihama et al. Phys. Rev. C 73 (2006) 035214 gn -> K+S- H. Kohri et al. Phys. Rev. Lett. 97 (2006) 082003 gp -> K+L K. Hicks et al. Phys. Rev. C 76 (2007) 042201(R) gp -> K+S-(1385) K. Hicks et al. Phys. Rev. Lett. 102 (2009) 012501 gp -> K+L(1405), S0(1385) M. Niiyama et al. Phys. Rev. C 78 (2008) 035202 gp -> K+L(1520) N. Muramatsu et al. Phys. Rev. Lett. 103 (2009) 012001 *gp -> K+L(1520) H. Kohri et al. Phys. Rev. Lett. 104 (2010) 172001

(C) Pseudoscaler meson photoproduction gp -> p0p M. Sumihama et al. Phys. Lett B 657 (2007) 32 gp -> hp M. Sumihama et al. Phys. Rev. C 80 (2009) 052201(R)

(D) Search for exotic resonance state Pentaquark search T. Nakano et al. Phys. Rev. Lett. 91 (2003) 012002 Pentaquark search T. Nakano et al. Phys. Rev. C 79 (2009) 025210