PST05, Nov 14-17, 2005, Tokyo
RIKEN
Production of spin-oriented unstable nuclei via the projectile-fragmentation reaction
H. Ueno @RIKEN
RIKEN
Measurement of & Q moments
Known nuclear moments
ground states
excited states Data are taken from“Table of nuclear magnetic dipole and electric quadrupole moments”, N.J. Stone, 2001
RIKEN
Ground states
Excited states (Isomer)
Method vs lifetime
1(fs) 1(ps) 1(ns) 1(μ s) 1(ms) 1(s)
TF
TDPAD
β-NMR
stbl
AB
IPACTDPAC
1(M) 1(H)1(D)
NMR
IPAD, RIGV
ME
CFBLS
onlin
e
offli
ne
RIKENISOL based RIBs
•ISOL based RIBs–target fragmentation, fission, and spallation– extraction –low energies
○ high production rates × slow process (lifetime τ limitation)× limited to chemically active elements (Z limitation)
• ARENAS, Louvain-la-Neuve• ATLAS, Argonne• EXCYT, Catania• HRIBF, Oak Ridge• ISAC, TRIUMF• ISOLDE, CERN• PIAFE, ILL• SPIRAL, GANIL• TRIAC, KEK• TWINSOL, Notre Dame • ……..
Isotope-Separation On Linetarget fragmentatione.g. p+UCx
RIKENFragmentation based RIBs
•Fragmentation based RIBs
–projectile fragmentation–high (intermediate) energies
○ no limitation from τ and Z× large spread of momentum & beam divergence
• RIPS, RIKEN• FRS, GSI• A1900, NSCL• LISE, GANIL
RIKENTechniques of μ & Q measurements for ISOL and PF based RIBs
• Ground states– Tilted-foil– Optical pumping
(Laser)
• Excited states– Coulomb
excitation
• Ground states– Fragmentation
• Excited states– Coulomb
excitation– Fragmentation
ISOL PF
PST05, Nov 14-17, 2005, Tokyo
RIKEN
Ground-state nuclear moments
RIKEN
Mechanism of the spin-polarization in P. F. reaction
target
fragment(spectator)
at the reaction(participant—spectator model)
R
Lspectator = 0 - Lparticipant
after the reaction
Fragment with High p
+L
Fragment with Low p
―L
p
p
participant
Lparticipant= x pR
RIKEN
Behavior of the spin-polarization in the P. F. reaction
Detector
Large-Z target
Near-side trajectory
Detector
Small-Z target
Far-side trajectory
H. Okuno et al., PL B335,29 (1994)
1. Spin-polarization can be produced simply by selecting p and Θ of outgoing fragments.
2. Size of polarization is typically 1-5 %.
3. Independent of chemical properties.
4. Fragments can be deeply implanted into the stopper material.
× 11Be, 19C (s1/2 nature)
Properties of the fragment-induced polarization
14,15N→12,13B
Au AlNbNbAu
RIKENβ -NMR
β -ray angular distribution:W(θ)=1+APcosθ
A: Asymmetry parameterP: Polarization
(1+AP)(1-AP)
(U/D)RFoff =
e- e-e-e-
e-e-
(U/D)RFoff = (1-AP)(1+AP)
e-e-e-e-
e- e-
RF coil
NMR
Required # of nucleiConventional NMR: ~1020
β-NMR : ~104
High sensitivity → RIB application
β-NMR method: K. Sugimoto et al., J. Phys. Soc. Japan 21 (1966) 213.
RIKEN
Optical pumping
1) Production of atomic polarization by laser
2) This polarization is transfered to the nuclear spin via hfi
Experimental setup at ISOLDE
Taken from ISOLDE web site
RIKEN
ISOLDE
31Mg11Be
RIKENRecent ground-state μ &Q-measurements of the unstable nuclei
• RIKEN – Discovery of spin-polarization in PF K.Asahi et al., PLB 251, 499 (1990)– 10 μ –moments & 5 Q–moments in the neutron-rich p-shell Osaka Gr. & TITech Gr.– μ [30, 32Al] H. Ueno et al., PLB 615, 186 (2005)– Q [31, 32 Al] (TITech Gr.)
• GANIL– μ [ 32Cl] W.F. Rogers et al., PRC 62, 044312 (2000)– 27Na, 31Al polarization D. Borremans et al., PRC 66, 054601 (2002)– μ [ 31Al] D. Borremans et al., PLB 537, 45 (2002)
• MSU– Spin-polarized RIBs @MSU P.F. Mantica et al., PRC 55, 2501 (1997) – 37K polarization in single-proton pickup reaction @E=150AMeV
D.E. Groh et al., PRL 23, 202502 (2003)• GSI
– 37K polarization @E=500AMeV M. Schaefer et al., PRC 57 2205 (1998)
• ISOLDE– μ &Q [ 11Li ] E.Arnold et al. PLB 281, 16 (1992)– μ [ 11Be ] W. Geithner et al., PRL 83, 3792 (1999)– μ [ 31Mg] G. Neyens et al., Phys.Rev.Lett. 94, 022501 (2005)
Fragment induced spin-polarization + β-NMR method
Optical pumping + β-NMR method
PST05, Nov 14-17, 2005, Tokyo
RIKENIsomer-state (τ ∼ μs) nuclear moments
γ -ray detectors
beam
W(θ) W(θ + • t )
target
spin-alignment produced in the Coulomb excitation reaction
B0 field
stopper material
gμ NB0
ℏ
TDPAD
RIKEN
Spin-alignment in the PF reaction
K. Asahi et al., Phys. Rev. C 43, 456 (1991)
• Spin-alignment is produced as a function of ejectile momentum
46Ti(E=500 AMeV) + Be→ 43Sc
W.-D. Schmidt-Ott et al., Z.Phys. A350, 215 (1994)
RIKEN
Isomer ratio in the PF reaction
F: fraction of the isomeric states
F = Nisomer
Ntotal
B.M. Young et al., Phys. Lett. B 311, 22 (1993)
PF is better way to produce spin-aligned RIBs
RIKEN
TDPAD exp. at GANIL
G. Georgiev et al., Eur. Phys. J. A 20, 93-94 (2004)
76Ge(E=61.4 AMeV)+Be→ 67mNi (t1/2=13.3μ s), 69mCu(t1/2=0.35μ s),
Spin-alignment produced in PF reaction
PST05, Nov 14-17, 2005, Tokyo
RIKENShort-lived excited state (τ ∼ ps)
γ -ray detectors
ferromagnet
beam
W(θ) W(θ+θTF)
1st target
Transient-field method
RIKEN
Low erengies• LBL
– First g factor measurement with RI beams (76Kr) −K.-H. Speidel et al., Eur. Phys. J. A 25, s01, 203{304 (2005)
• ISOLDE– g-Factor measurements of 132, 134, 136 Te
Intermediate energies (PF reaction)• RIKEN
– BTF strength @v ~ Zv0 H. Ueno et al., Hyperfine Int. 136/137, 2 (2001)
A. Yoshimi et al., Nucl. Pys. A 738, 519 (2004)
• MSU– v/Zv0 distribution→ discussion on the BTF strengths @v ≥Zv0
A.E. Stuchbery PRC69, 064311 (2004)
– g factor measurements of − 38, 40S produced in the PF reactionsA.D. Davis, A.E. Stuchbery, P.F. Mantica et al., DNP2005
Transient Filed: τ ~ ps
Status of μ (21+) measurements for unstable nucle
i
RIKEN1st TF expeiment with RIB
MgGdTa
Mg
Beam
N. Benczer-Koller et al., Eur. Phys. J. A 25, s1.203-s1.304 (2005)
1st RIB-expeiment
76Kr(T1/2 = 14.8 h) @ LBL
I = 106 cps x 5 days74Se(α, 2n)76Kr @E=38MeV
Magnetic Moments of Coulomb Excited 21+
States for Radioactive Beams of 132, 134, 136Te Isotopes at REX-ISOLDE
RIKEN
TF exp. at MSU
A User's Perspective
The Transient-Field Technique in a New RegimeAndrew Stuchbery, Australian
High energy RIBs (PF reaction)
38S and 40Sthe first 2+ states (τ∼ps)
Au (355 mg/cm2)
Fe (110 mg/cm2)38,40S (E=40 AMeV)
38,40S*
RIKENBTF at v > Zv0
5 10 15 20
1
2
3
high-velocity region: vion> Zv0
N.K.B. Shu et al., PRC21, 1828 (1980)
BTF=4π Z·v0/vion·μ BNp
G. Hagelberg et al., Z. Phys. D17, 17 (1990)
VSE (eproj e⇄ GdQfree)
24Mg+Gd
Ion velocity v/vion
BT
F (
kT
)
0
low-velocity region: vion≲ Zv0
Eberhardt et al.Hyp. Int. 3, 195 (1977) Empirical BTF=a·Z·vion/v0
(a Fe =12, a Gd =17)
?? F. Hagelberg et al., PRC48, 2230 (1993)
VSE (eionic-shell e⇄ GdLocalized)
BTF=p1s x q1s
p1s prediction
RIKEN
• 6” NaI x 4• Target Au+Gd
Target ladder cooled toT∼100K• Coil (Bext = 300 Gauss)
Bext Up & Down in every 15 sec.• 30 plastic scintillators for particle coincidence
targetladder
liq.N2
container
RIKEN-setup for TF experiments
RIKEN
Comparison with the systematic
K.-H. Speidel et al.PLB324(1994)130
BTF=a Z vion/v0
a=12 (Fe)a=17 (Gd)
Stopping power > 4.5 MeV/μm
BTF=1.2(2) kT
Mg (Gd)
BTF values of 28Si and 24Mg
deviation but substantial magnitude
PST05, Nov 14-17, 2005, Tokyo
RIKEN
Recent measurement of ground-state nuclear moments at RIKEN
RIKEN
Production of spin-polarized RI beam with RIKEN Projectile fragment Separator (RIPS)
RIPS
K=540 RIKEN Ring Cyclotron
RIKEN
NMR apparatus
β -NMR:w(θ)=1+APcosθ
(U/D)off = (1+AP)/(1-AP)(U/D)on = (1- AP)/(1+AP)
NMR technique: the AFP method
e-e-e-e-
e- e-e-e-e-
e-
RIKEN
• g-Factors measured at RIKEN– Boron isotopes : 14B, 15B, 17B– Carbon isotopes : 9C, 15C, 17C– Nitrogen isotopes : 17N, 18N, 19N– Oxygen isotopes : 13O
• Q-moments measured at RIKEN– Boron isotopes : 14B, 15B, 17B– Nitrogen isotopes : 18N– Oxygen isotopes : 13O
Study of the p-shell nuclei through their nuclear moments
TITech / RIKEN
Osaka / RIKEN
Spin-parity assignment
Reduction of E2 effective charges
RIKEN
I = 0
g-factor known
Recent μ -measurements in the sd shell
Island of inversion
N=20
GANILISOLDE
RIKEN
RIKEN
Neutron-rich Al isotopes (theory)
E. Caurier et al., PRC58(1998)2033 Y. Utsuno et al., PRC 64(2001)011301(R)
33Al31Al 32Al 33Al 34Al
• 33Al is turning point of the inversion between 0p-0h and 2p-2h configurations along N=20
• decreases from 31Al(30Al)→33Al• E0p0h-E2p2h > 0 for Al isotopes, but similar to Mg, Na, Ne
Al: near the border line of Island of Inversion
RIKENμ -moments of 30Al & 32Al
• The result provides a promising prospect that substantial polarizations are obtained for the other sd-shell nuclei
H. Ueno et al., PL B615, 186 (2005)
RIKEN
Comparison with shell model prediction
In both 30Al and 32Al cases, no disagreement is observed between μ exp and μ SM(USD)
Amplitude of intruder configurations is larger for 32Al ?
H. Ueno et al., Phys. Lett. B 615, 186-192 (2005)
RIKEN
Precisionmeasurement
Wide-rangescan
Q [32Al] (preliminary)
RIKEN
Q [31Al] (preliminary)
Wide-rangescan
Precisionmeasurement
3.5σ statistics
RIKENSummary
• Grond-state nuclear moments have been measured in RIB facilities.• Measurements for the excited states have started.
at RIKEN
• Nuclear moments have been measured in the p-shell region by means of the β-NMR method + fragment-induced polarization.– μ-moments enhancement of (sd)2+, J π assignment– Q-moments reduction of the E2 effective charges
• In the sd-shell μ [30,32 Al] and Q [31,32 Al] have been measured.– 40Ar→30Al (10-nucleon removal) was spin-polarized: P ~ 1%– Next: 33, 35Si, Q(33Al), μ (34,35Al), 33-37P, 33Mg
RIKENCollaboration
K. Asahi, M. Takemura, G. KijimaK. Shimada, D. Nagae, M. Uchida, T. Ar
aiH. Miyoshi, G. Kato, K. Emori, M. TsukuiTokyo Institute of Technology
H. Ueno, D. Kameda, A. Yoshimi, T. Haseyama, Y. Kobayashi, H. Sato, H. Okuno, N. Aoi, K. Yoneda, N.Imai, N. Fukunishi, A. Yoshida, T. Kubo, M. Ishihara RIKEN
T. KawamuraRikkyo Univ.
H. OgawaAIST
H. WatanabeAustralian National Univ.
H. Izumi, W. Sato, T. ShimodaOsaka University
H. Miyatake, Y.X. WatanabeKEK
W.-D. Schmidt-OttUniversitaet Goettingen
G. Neyens, S. TeughelsLeuven