polarized proton solid target at high-t and low-b tomohiro uesaka center for nuclear study, tokyo
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Polarized Proton Solid Targetat high-T and low-B
Tomohiro UesakaCenter for Nuclear Study, Tokyo
T. U
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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
ariz
atio
n [
%]
Pol
ariz
atio
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 )
400 500 600Wavelength (nm)
[ M . Iinuma, private c ommunicat ion]
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
400 500 600Wavelength (nm)
[ M . Iinuma, private c ommunicat ion]
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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CNS Phenomenological Optical Model Analysis
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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CNS Phenomenological Optical Model Analysis
2. Spin-orbit term
Initial pot. : Obtained in 1.
Fitted data : Ay
CH89
Preliminary Preliminary
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CNS Phenomenological Optical Model Analysis
2. Spin-orbit term
Initial pot. : Obtained in 1.
Fitted data : Ay
Preliminary Preliminary
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CNS Phenomenological Optical Model Analysis
2. Spin-orbit term
Initial pot. : Obtained in 1.
Fitted data : Ay
Preliminary Preliminary
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CNS Phenomenological Optical Model Analysis
2. Spin-orbit term
Initial pot. : Obtained in 1.
Fitted data : Ay
minimum
Preliminary Preliminary
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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
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