Polarized Proton Solid Target at high-T and low-B

Polarized Proton Solid Targetat high-T and low-B

Tomohiro UesakaCenter for Nuclear Study, Tokyo

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CNS Outline

• Polarization study of nuclei

spin-orbit coupling in nuclei

early experiment by O. Chambalain

motivation to RI beam studies

• Polarized proton solid target at high-T and low-B

use of photo-excited triplet state of aromatic molecule

• Future plan

RI Beam Facility at RIKEN

• Summary

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CNS Spin-orbit force in nuclei

Mayer & Jensen claimed in 1948 strong spin-orbit force:

necessary to account for the magic numbersone order stronger than the Thomas term

O. Chamberlain et al. Phys. Rev. 102 (1956) 1659. measured Ay (Py) for p- He/Be/C/Al/Ca/Fe/Ta through double scatt.method → direct evidence of

spin-orbit force

E. Fermi , Nuovo Cimento 10 (1954) 407.

VLS deduced from the scattering experiment is consistent with that required by the shell model

scattering angle [deg]

Pol

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CNS Initiation of polarization study

Polarized ion source (~1956)

Claussnitzer, Fleishmann

→ spectroscopy of single particle

states via (d,p)/(p,d) reactions.

→ clarify the role played by

spin dependent interactions

Polarized target (DNP)

O. Chamberlain et al.

Bull. Am. Phys. Soc. 8 ('63) 38.

La2Mg3(NO3)12 24H2O

B = 1.8 T

T = 1.2 K

P ~ 50%

from Jefferies's Textbook

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CNS Spin dep. interaction

Basic regularity in nuclei ← spin dependent interaction

shell structure ← spin-orbit force

magic numbers: 2, 8 , 20, 28, 50, 82, 126. . . .

saturation ← tensor force

same density (0.17 nucleon/fm3) everywhere

pairing of like particles

Polarization studies have made great contributions to clarify manifestations of spin dependent interactions in nuclei.

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CNS Physics far from the stability line

New data from experiments with RI beam 　→ "basic" regularities are valid only locally

in the vicinity of the stability line.

halo: low density neutron matter

J=0 pairing of unlike particles change of shell structure:

disappearance of "old" magic numbers appearance of "new" magic numbers

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CNS Polarized Proton Targets for RIB

Requirements on the polarized proton target for RI beam exp.

RI beam : Low intensity of < 106 Hz

high-density solid target gas targetany p solid target: compound including hydrogen atoms detection of recoiled protons: essential for event ID

5 MeV proton: range < 0.2mm in Al　 B = 0.33 Tm

conventional p targets at low T(<1K) and at high B (>2.5T) places serious difficulty in proton detection.

B=2.5 T → ~ 13cm

Solutions

spin frozen target (Oak Ridge-PSI collaboration)

new technique to polarize at low-B and high-T

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CNS Proton Pol. at low-B and high-T

Idea: use of electron polarization (population difference)in photo-excited triplet state of aromatic molecule

H.W. van Kesteren et al., Phys. Rev. Lett. 55 (1985) 1642.

A. Henstra et al., Phys. Lett. A 134 (1988) 134.

T1

Triplet state

(12%)

S0

S1

Singlet state

Laser(76%)

(12%)

population

+1

0

-1

S2

Energy diagram of pentacene molecule

mixing due tospin-orbit int. in molecule

Electron polarization

depends neither on B nor T

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CNS Electron population difference

x

yz B // x : Pmax = 73%B // y : Pmax = 48%B // z : Pmax = 70%

B // x B // y B // z

Crystal alignment is essential for large polarization

0.12

0.12

0.76

0.45

0.39

0.16

0.46

0.46

0.08

Pentacene molecule

Population

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CNS Host materials

Naphthalene C10H8 p-terphenyl 　 C18H14

density 1.16 g/cm3

pentacene concent. 0.01 mol%melting point 80.2 deg.

density 1.24 g/cm3

pentacene concent. 0.1 mol%melting point 　　　　 208 deg.

K. Kouda et al. J. Phys. Soc. Jpn. 51, (1982) 3936.

J. U. von Shuetz et al. Z. Nauturforsch. 22a, (1967) 643.

phase transition (193 K)

10-4

10-2

100

102

Rel

axat

ion

rate

[min

.-1]

100 200 300 400Temperature [K]

impurityslow molecularmotion (∝ H-1/2)

naphthalene @0.09 T

p-terphenyl @0.46 T

low T : naphthalenehigh T : p-terphenyl　

Rel

axat

ion

rat

e [/

min

]

　 Temperature [K] 　

pentacene

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CNS Technical aspects

Optical pumpingpol. light is not necessarybroad spectral width : less demands on laser

Ar-ion laser, dye laser, YAG laser, etc.

Polarization transfer to protons at low B

cross polarization method (Hartmann & Hahn, PR 128 (1962) 2042.)

high efficiency even at low B

Cooling

operation temperature ~ 100 K

blow of cold nitrogen gas is sufficient

→ decrease materials around the target

400 500 600Wavelength (nm)

[ M . Iinuma, private c ommunicat ion]

Ar- ion

Dye

YAG

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CNS Application to Part. & Nucl. Physics

Masaike, Iinuma et al. (Kyoto)

M. Iinuma et al., Phys. Lett. A 208 (1995) 251.

M. Iinuma et al., Phys. Rev. Lett. 84 (2000) 171.

K. Takeda et al., Chem. Phys. Lett. 345 (2001) 166.

applied this novel technique to neutron beam experiments

naphthalene+pentaceneT=77KB=0.3T

Laser: dye laser, 350 mW

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CNS Optical pumping by Ar-ion Laser

System for basic study with Ar-ion laser T. Wakui et al., NIM A 526 (2004) 182 & NIM A 550 (2005) 521.

Protonpolarization :36.8±4.3%(39.3±4.6%)

0510152025303540

0 2 4 6 8 10 12

Polarization(%)

Time (hours)

Polarization in naphthaleneat 0.3 T, 100K

crystal size 4×4×3mm3

Polarization in p-terphenyl

at 0.3T, room temperature

4.8±1.2%enhancement factor > 5×104

0

2

4

6

0 50 100 150 [%]

偏極

度 [ ]時間分Time [min]

Time [hours]

Pol

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n [

%]

Pol

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n [

%]

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CNS Development for RI beam exp.

• production of large single crystal and shaping it to thin disk with large diameter.

14mmφ, 1mm-thickness

• thin microwave resonator (f = 2 － 3GHz)

copper film loop gap resonator

• improvement of NMR sensitivity

• reduction of material around the target

target cooling with blowing cold N2 gas

• evaluation of radiation damage due to HI irradiation

• polarization measurement with p-4He scattering

thermal polarization measurement: impossible

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CNS Target system & Polarization

small effects

of radiation

damage

Polarization at 0.08T and 100K

RI beam

laser light

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CNS First experiments

effects of excess neutrons on spin-orbit potential?

proton elastic scatterings on helium isotopes

4He 6He 8He

N/Z=1 N/Z=2 N/Z=3

rm =1.49 fm rm=2.30 fm rm=2.45 fm

S2n=28.3 MeV S2n=1.86 MeV S2n=2.58 MeV

halo (or skin?) skin

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CNS p-6He Elastic scattering at 71 MeV/u

Theoretical predictionsbefore the measurement

Preliminary results at RIPS, RIKEN

S. P. Weppner et al. Phys. Rev. C 61 (2000) 044601.

There exists something beyond our current understandings.The effect appears only in spin polarization data.

Measurement for 8He is planned in 2007.

Sakaguchi et al.

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CNS RI Beam Factory at RIKEN

high resolution SHARAQ Spectrometer

Use of the polarized target enhances scientific opportunities with RI beam at RIBF. proton elastic scatterings (p,pN) reactions for spectroscopy of single hole states (p,p') and (p,n) reactions to deduce spin responses

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CNS Summary

A new technique to polarize protons at low-B and high-T is developed.

by use of photo-excited triplet state of aromatic molecule.

The proton polarization has been applied to a radioactive nuclear beam

experiment at RIPS, RIKEN.

p-6He elastic scattering at 71 MeV/u

The result is beyond our current understandings.

Scientific opportunities with radioactive isotope beams are expanding.

It should be exciting to shed a light of POLARIZATION to the field.

Polarization of radioactive nuclei: P. Mantica, H. Ueno etc.

Scattering of polarized protons: this talk, Oak Ridge-PSI

A role played by spin physics community is very important.

spin physics community ⇔ heavy ion physics community

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CNS Collaborators

CNS, TokyoT. Wakui (→CYRIC), S. Sakaguchi, T. Kawabata, K. Suda,Y. Maeda, Y. Sasamoto, T. Uesaka

Dep. of Physics, TokyoM. Hatano (→Hitachi), H. Sakai, K. Yako, H. Kuboki, M. Sasano,H. Iwasaki, Y. Ichikawa, D. Suzuki, T. Nakao

Toho UniversityT. Kawahara

Saitama UniversityK. Itoh

RCNP, Osaka UniversityA. Tamii

CYRIC, Tohoku UniversityH. Okamura, M. Itoh, R. Matsuo, M. Ichikawa

Tokyo Institute of TechnologyY. Satou, Y. Hashimoto, M. Shinohara

RIKENN. Aoi, K. Sekiguchi, M. Yamaguchi

BACKUP

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CNS Research plans at RIBF

RIBF energy: 150 － 350 MeV/u

nuclei are most transparent.

Proton elastic scattering

Spectroscopic studies with (p,pN) reactions

→ 　 unambiguous determination of the spin-orbit splitting

Spin responses of unstable nuclei via (p,p') and (p,n) reactions

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CNS

KEYS:

・ Large spin correlation in N-N scattering, Cy,y ~0.8, at E/A~200 MeV

↑↑ 　≫ ↑↓

→ 　 incident proton interacts mostly with nucleon with the same spin

・ Distortion to recoiled (low energy) nucleon

if recoiled nucleon goes into the target nucleus → 　 absorbed

Method of Effective Polarization

proton with spin↑

R

L

L

j<

j>

if pN < 0

Ay < 0 for j>

Ay > 0 for j<

pN < 0

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CNS

16O(p,pp) @ 215 MeV

p1/2 p3/2

16O(p,pp) @ 200MeV

Method of Effective Polarization

G. Jacob et al., Phys. Lett. B 45 (1973) 181.

P. Kinching et al., Nucl. Phys. A 340 (1980) 423.

pN

Ay

d3/d1d2dE

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CNS (p,pN) at RIBF

E/A = 200250MeV:

best energy for the study

1) weak distortion for incoming and

scattered proton

Ep=150 － 250MeV

2) modest absorption for recoiled nucleon

EN=50 － 100MeV

3) large spin-correlation parameter

in N-N scattering

Cy,y ~ 0.8

4) reaction theory established

relativistic DWIA

G.C. Hillhouse et al.

Ep [M

eV]

[deg]

Cy,y for p-p scattering

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CNSSpectroscopy of particle/hole state

Shell regularity in the region far from the stability linehow p (n) spin-orbit splitting

depends on n (p) number?

Experimental approach:nucleon transfer reactions

→ 　 low energiesnucleon knockout reactions

→ 　 intermediate energies: RIBF

Is the Nuclear Spin-Orbit Interaction Changing with Neutron Excess?J. P. Schiffer et al., PRL 92 (2004) 162501. NA

Ej<E

j'>

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CNS Experiments at RIBF

(p,pp) Ni , Sn, Ca isotopes

(p,pn) N=50, 28 isotones

from BigRIPS

SHARAQ

proton detectors

neutron detectors

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CNS p-8He 　 Elastic Scattering

R. Crespo et al., PRC 51 (1995) 3283.

p+8He

full

core

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CNS Polarized proton targets by DNP

Transfer thermal polarization of electrons to protons

by microwave irradiation

large magnetic moment of electron

→ large Pe at low-T (<1K) and high-B (>2.5T)

hyperfine interaction between electron and proton

rapid spin relaxation of electrons

slow spin relaxation of protons

　　 Solid effect (or Overhauser effect)

A.W. Overhauser Physical Review 92 (1953) 411.

[1] C.D. Jefferies, Dynamic Nuclear Orientation (1963)

[2] A. Abragam, The Principles of Nuclear Magnetism (1961)

[3] A. Abragam and M. Goldman, Nuclear Magnetism: Order and Disorder (1982)

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CNS Magic numbers

2, 8, 20, 28, 50, 82, 126 . . . .

believed to be universal throughout the nuclear chart.

BUT, this has proven not to be true.

← 　 new data from radioactive nuclear beam experiments

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CNSReactions with spin-polarized probes

Invention of polarized ion source (1956) by Claussnitzer, Fleishmann

→ 　 drastic progresses in polarization study

firm basis of LS potential local and global optical potentials

VLS ~ 5 MeV

weak dependence on E, A

A.J. Koning & J.P. Delaroche

Nuclear Physics A 713 (2003) 231.

n-56Fe

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CNS 新光源 : 高輝度発光ダイオード

Luxeon 社 ~100 mW @300mA

波長 : 590nA時間構造 : 電流で制御安価 (2000 円 / 個 )



Ar- ion

Dye

YAG

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CNS Polarized proton solid target

Many deep inelastic scattering experiments

EMC(→SMC)→COMPASS @CERN

SLAC

Production of spin-polarized neutron (ex. KEK)

large difference between ↑↑and ↑↓

Nuclear physics experiments

CNS group → 　 unstable nuclear physics experiment

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CNS Gyromagnetic Ratio

ratio of magnetic moment to angular momentum

for electron and proton

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CNS 結晶近傍

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CNS 装置の全貌

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CNSDetailed Study of Radiation Damage

Polarization is determined by competition of A and

0.00

0.05

0.10

0.15

0

2

4

6

8

10

12

0 5 10 15 20 25 30

Pol

ariz

atio

n [a

rb. u

nits

]

Cum

ulated Counts [×

109]

Time [hours]

Polarization

Counts

Radiation damage due to HI irradiation　　　 before irradiation 　 0.1 h-1

after irradiation 　 0.3 h-1 (2×1010)

0

0.1

0.2

0.3

0.4

0 20 40 60 80 100R

elax

atio

n ra

te

B [

h-1]

Time [hours]

100 K

150 K

200 K

The damage can be cured at temperature higher than 200K.

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CNS Early work at Leyden

Schmidt group at LeydenH.W. van Kesteren et al., Chem. Phys. Lett. 89 (1982) 67.

Chem. Phys. Lett. 121 (1985) 440. Phys. Rev. Lett. 55 (1985) 1642.

Fluorene + Phenanthrene 固体効果 ( 低磁場では効率悪い )

Pp ~ 2% @ 0.3T, 1.2K → 　 42% @ 2.7T, 1.4K

P~2%

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CNS Polarization at Lower Field

A. Henstra et al., Leyden group

A. Henstra et al., Phys. Lett. A 134 (1988) 134.

A. Henstra et al., Chem. Phys. Lett. 165 (1990) 6.

Naphthalene + Pentacene

　 Cross polarization method

efficient even at low magnetic field

29Si:BT=1.2KB=0.264T

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CNS ナフタレンの純化

ゾーン・メルティング法融点以上のゾーンを通過させる

不純物が偏析する

ヒーター (molten zone)

不純物液化領域 (90 C)

固体領域 (25 C)

10mm/h

純化されたナフタレン

不純物(Benzo thiophene)

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CNS 単結晶の製作

ブリッヂマン法1 mm/h

シリコンオイル(90 )℃

グリセリン(25 ℃)

キャピラリーで生じた結晶が種となり大きな単結晶に成長

ヒーター

ナフタレンの融点 :80 度

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CNS Cross Polarization

0

10

20

30

40

50

60

τ0

electronproton

effectiveLamorfrequency

(MHz)

time

e (rot. frame) p (rot. frame)

energyexchange

Hartmann-Hahnの条件(交差緩和)

equalize Zeeman splittings of different speciesS.R. Hartmann and E.L. Hahn, Phys. Rev. 128 (1962) 2042.

歳差運動と近い周波数を持つ回転磁場中にスピンを置いた時、スピンが感じる有効磁場はだけ減ぜられる。

回転磁場の周波数が歳差周波数と離れていれば影響ほぼ無し

H eff = H 0 -ωγ +H 1

H0

H1

ωγ

Heff

　　　磁場の強さ　　　

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CNS Hartmann-Hahn 条件

0

10

20

30

40

50

60

τ0

electronproton

effectiveLamorfrequency

(MHz)

time　　外磁場の強さ　　　

電子の有効ラーマー周波数が陽子の周波数と一致する時間：

接触時間 (contact time)

接触時間が長い方が偏極移行率が

大きくなる。

極小値の値はマイクロ波の強度で決まる。

結晶の内部磁場による広がり : 数 mT

　　　外磁場を掃引ことにより、

　　　全ての site で遷移を起こす。

マイクロ波強度 [W] ⇔ H1

"ス

ピン

移行

率"

H-H 条件

ESR

数 mT

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CNS 偏極度測定：パルス核磁気共鳴法

M

H1

x’

y’

z’ 1' H

1H t

角度： RF 場の強さ、パルス幅で決まる

突然横磁場 (RF) をかける　　→　スピンが倒れ、 z 軸の周り

に回転する。　　→　 xz 平面に置かれたコイル

に誘導起電力発生

横磁場を切った後は、非一様磁場やスピンスピン相互作用のためスピン軸の回転位相がばらばらになり、信号強度が減衰する。

　　 Free Induction Decay (FID)

p: 2.68×108/T/s

FID 信号の例

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CNS パルス NMR

回転角を使い分ける信号強度 ~ sin()減偏極 ~ 1-cos()

弱パルス (~5 度 ): 偏極度モニター

90 度パルス :熱偏極信号パラメータ調整時

180 度パルス：偏極反転

河原 et al.

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CNS 光ポンピング用レーザー

T 1

T rip le t s ta te

S 0

S 1

S in g le t s ta te

18 μ s (76%)

+1

0

- 1

25 μ s(12%)

25 μ s (12%)

9 ns 40%

60%

ペンタセンのエネルギー準位



Ar- ion

Dye

YAG

吸収スペクトル

レーザーの候補フラッシュランプ励起色素レーザー　　　 Pulse width 　　 : 800 ns　　　 Repetition rate : 50 Hz　　　 Average power : 350 mW

アルゴン - イオンレーザー (CW) 　　　 Average power : 500 mW (25 W, 1 kHz, 20 s)YAG レーザー　　　 Pulse width 　　 : 10 ns　　　 Repetition rate : 30 Hz　　　 Average power : 3 W

Kyoto group 32% [M. Iinuma et al. Phys. Rev. Lett. 84, (2000) 171.]

色素の寿命 < 100 時間

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CNS Phenomenological Optical Model Analysis

• Analysis procedure

1. Differential cross section

→ Central term

→ Volume abs. term

2. Analyzing power data

→ Spin-orbit term

1. Central and volume absorption term

Initial pot. ： 6Li potential

Fitted data ： d.c.s.

Preliminary

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CNS THIN microwave resonator

Copper film loop gap resonator B. T. Ghim et al., Jour. Mag. Reson. A 120 (1996) 72.

thin Teflon tube coated with

copper film on both sides

d = 16 mm z = 20 mm w = 272 m t = 25 m n = 15

L=9.7 nH , C = 0.29 pF f = 3.0 GHz

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CNS LS potential in neutron-rich nuclei

LS potential

localized on the nuclear surface

1) should be modified

in neutron-rich nuclei

where neutron and proton

have different surfaces.

2) extended distribution of neutrons

may affect the shape of LS potential.

direct evidence from p-RI scattering needed-> 　 the polarized proton target + RI

beam

p+6He Experiment at RIPS, 71 MeV/A

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CNS Microscopic Theory K.Amos et al., Adv. Nucl. Phys. 25

d/d

Ay

Tar

get

Mas

s

Scattering Angle

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CNSp-6He Elastic Scattering

d/d measurementsDubna　　 25 MeV R. Wolski et al., PLB 467 (1999) 8.GANIL　　 38.3 MeV V. Lapoux et al., PLB 517 (2001) 18.　　 40.9 MeV A. Lagoyannis et al., PLB 518 (2001) 27.RIKEN 71 MeV A. A. Korsheninnikov et al., NP A 616(1997) 45.GSI 700 MeV G. D. Alkhazov et al., PRL 78 (1997) 2313.

p-6He, 8He, 11Li. . . Scatterings matter (neutron) distribution most fundamental direct reaction

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CNS Detector Setup

TARGETNaphthalene crystal14mm ×1mmt

Detector Telescope for protons PSD for E and position Plastic Scintillator for E

Detector Telescope for 6He MWDC for ray-tracking Plastic Scintillator

E (5mm)-E(30mm×2)

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CNS Event Identification

• Small dilution factor of naphthalene target

C10H8 : dilution factor = 6.3%

particle identification

of recoiled particle

• Contribution from carbon

rejected using kinematic condition

p-6He Correlation p-6He Correlation

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CNS Elastic Scattering Events

Angular correlationbetween p and 6He

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CNS p+6He Elastic Scattering

p+6He elastic at 71MeV/u

　 A. Korsheninnikov et al. (open)

　 Nucl. Phys. A 616 (1997) 45.

　 This Work (solid circles)

p+6Li elastic at 72MeV

R. Henneck et al.,

Nucl. Phys. A 571 (1994)541.

p+4He elastic at 72MeV

　 S. Buezynski et al.,

Phys. Rev. C 39 (1989) 56.

Preliminary

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CNS Microscopic Calculations

Folding Models

t-matrix

Weppner et al.

Crespo et al.

g-matrix

Amos et al. Melbourne int.

Gupta et al., JLM + LS of global potential

Iseri et al., CEG, cluster-folding

Relativistic Impulse

Kaki et al.

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CNS St Petersburg-Ohio Group

S. P. Weppner et al. Phys. Rev. C 61 (2000) 044601.

Folding Nijmegen I interaction for several density distributions

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CNSPredictions of Microscopic Theories

D. Gupta et al. Nuclear Physics A 674 (2000) 77.

JLM approach, LS from global potential

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CNSPredictions of Microscopic TheoriesFolding density dependent effective interaction

with realistic density distribution (HO base)

K. Amos et al. private communication

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CNS +n+n folding potential

Iseri et al.

p- optical pot. (fitted)

p-n CEG

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CNS Relativistic Impulse

Kaki et al.

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CNS What is missing?

• Dynamical polarization potential

coupling to breakup states

• Contribution from

S=2 component in 4He ~10%

S=1 component in n-n ~10%

• isospin dependence of effective interactionLS potential ← tensor interaction

strong density dependenceJLM: no LS potentialCEG: based on HJ pot.

no density dependence in LS int.Melbourne: based on Paris pot.

density dependence in LS and tensor int.

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CNS Phenomenological Optical Model

Global potentialBeccheti-Greenlees A>40 E<50MeV Phys. Rev. 182 (1969) 1190.

Perey-Perey A>40 E<50MeV ADNDT 13 (1974) 293.

CH89 A>40 E<65MeV Phys. Rep. 201 (1991) 57.

Koning A>24 E<200MeV NPA713 (2003) 231.

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CNS Optical Potential for p-6Li

R. Henneck et al.,

NPA 571 (1994) 541.

V =31.67 MeV

rr =1.10 fm

ar = 0.75 fm

W =14.14 MeV

ri = 1.15 fm

ai = 0.56 fm

Vls = 3.36 MeV

rls = 0.90 fm

als = 0.94 fm

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2. Spin-orbit term

Initial pot. ： Obtained in 1.

Fitted data ： Ay

Preliminary

6He 6LiV = 20.2 MeV 31.67 MeVrr = 1.27 fm 1.10 fmar = 0.57 fm 0.75 fmW = 19.2 MeV 14.14 MeVri = 0.91 fm 1.15 fmai = 0.64 fm 0.56 fmVls = 2.70 MeV 3.36 MeV rls = 1.21 fm 0.90 fmals = 1.06 fm 0.94 fm

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2. Spin-orbit term


Fitted data ： Ay

CH89

Preliminary Preliminary

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2. Spin-orbit term


Fitted data ： Ay


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2. Spin-orbit term


Fitted data ： Ay

minimum


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CNS Phenomenological OMP analysis

Exp. Global 6Li

Vls (MeV) 2.3 5.90 3.36

rls (fm) 1.2 0.67 0.90

als (fm) 0.9 0.63 0.94

indication of extended shape

of 6He spin orbit potential

S. Sakaguchi et al.

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CNS System diagram

Polarized Proton Solid Target at high-T and low-B

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Transcript of Polarized Proton Solid Target at high-T and low-B