Production of spin-oriented unstable nuclei via the projectile-fragmentation reaction

1
Production of spin-oriented unstable nuclei via
the projectile-fragmentation reaction

• H. Ueno _at_RIKEN

2
Measurement of m 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
3
Method vs lifetime
1(fs)
1(ps)
1(ns)
1(µs)
1(ms)
1(s)
1(M)
1(H)
1(D)
stbl
TF
IPAD, RIGV
AB
online
TDPAD
ß-NMR
IPAC
CFBLS
TDPAC
NMR
offline
ME
4
ISOL based RIBs
Isotope-Separation On Line target
fragmentation e.g. pUCx

• ISOL based RIBs
• target fragmentation, fission, and spallation
• extraction
• low energies
• ? high production rates
• slow process (lifetime t 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
• ..

5
Fragmentation based RIBs

• Fragmentation based RIBs
• projectile fragmentation
• high (intermediate) energies
• ? no limitation from t and Z
• large spread of momentum beam divergence

• RIPS, RIKEN
• FRS, GSI
• A1900, NSCL
• LISE, GANIL

6
Techniques of µ Q measurements for ISOL and PF
based RIBs
ISOL
PF

• Ground states
• Tilted-foil
• Optical pumping (Laser)
• Excited states
• Coulomb excitation

• Ground states
• Fragmentation
• Excited states
• Coulomb excitation
• Fragmentation

7
Ground-state nuclear moments
8
Mechanism of the spin-polarization in P. F.
reaction
at the reaction (participantspectator model)
fragment (spectator)
participant
target
9
Behavior of the spin-polarization in the P. F.
reaction
14,15N?12,13B
Au
Al
Nb
Nb
Au
H. Okuno et al., PL B335,29 (1994)
10
ß-NMR
Required of nuclei Conventional NMR
1020 ß-NMR 104 High
sensitivity ? RIB application
ß-ray angular distribution W(?)1APcos? A
Asymmetry parameter P Polarization
(1AP) (1-AP)
(U/D)RFoff
NMR
ß-NMR method K. Sugimoto et al., J. Phys. Soc.
Japan 21 (1966) 213.
11
Optical pumping
Experimental setup at ISOLDE

1. Production of atomic polarization by laser
2. This polarization is transfered to the nuclear
   spin via hfi

Taken from ISOLDE web site
12
ISOLDE
13
Recent ground-state µQ-measurements of the
unstable nuclei
Fragment induced spin-polarization ß-NMR method

• RIKEN
• Discovery of spin-polarization in PF
  K.Asahi et al., PLB 251, 499 (1990)
• 10 µ moments 5 Qmoments 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 _at_MSU P.F.
  Mantica et al., PRC 55, 2501 (1997)
• 37K polarization in single-proton pickup reaction
  _at_E150AMeV
• 
  D.E. Groh et al., PRL 23, 202502
  (2003)
• GSI
• 37K polarization _at_E500AMeV M. Schaefer
  et al., PRC 57 2205 (1998)

Optical pumping ß-NMR method
14
Isomer-state (t µs) nuclear moments
TDPAD
?-ray detectors
B0 field
target
beam
gµNB0 ?
W(?)
W(? t )
stopper material
spin-alignment produced in the Coulomb excitation
reaction
15
Spin-alignment in the PF reaction

• Spin-alignment is produced as a function of
  ejectile momentum

46Ti(E500 AMeV) Be ? 43Sc
K. Asahi et al., Phys. Rev. C 43, 456 (1991)
W.-D. Schmidt-Ott et al., Z.Phys. A350, 215 (1994)
16
Isomer ratio in the PF reaction
B.M. Young et al., Phys. Lett. B 311, 22 (1993)
PF is better way to produce spin-aligned RIBs
17
TDPAD exp. at GANIL
Spin-alignment produced in PF reaction
76Ge(E61.4 AMeV)Be ? 67mNi (t1/213.3µs),
69mCu(t1/20.35µs),
G. Georgiev et al., Eur. Phys. J. A 20, 93-94
(2004)
18
Short-lived excited state (t ps)
Transient-field method
ferromagnet
1st target
beam
?-ray detectors
W(?)
W(??TF)
19
Status of µ(21) measurements for unstable nuclei
Transient Filed tps

• Low erengies
• LBL
• First g-factor measurement with RI beams (76Kr)
• K.-H. Speidel et al., Eur. Phys. J. A 25, s01,
  203304 (2005)
• ISOLDE
• g-Factor measurements of 132, 134, 136 Te
• Intermediate energies (PF reaction)
• RIKEN
• BTF strength _at_vZv0
  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 _at_v Zv0
• 
  A.E. Stuchbery PRC69, 064311 (2004)
• g-factor measurements of 38, 40S produced in the
  PF reactions
• A.D. Davis, A.E. Stuchbery, P.F. Mantica et al.,
  DNP2005

20
1st TF expeiment with RIB
1st RIB-expeiment 76Kr(T1/2 14.8 h) _at_ LBL I
106 cps x 5 days 74Se(a, 2n)76Kr _at_E38MeV
Mg
Beam
Mg
Ta
Gd
N. Benczer-Koller et al., Eur. Phys. J. A 25,
s1.203-s1.304 (2005)
Magnetic Moments of Coulomb Excited 21 States
for Radioactive Beams of 132, 134, 136Te Isotopes
at REX-ISOLDE
21
TF exp. at MSU
High energy RIBs (PF reaction)
                                      A User's
Perspective The Transient-Field Technique in a
New Regime Andrew Stuchbery, Australian
38,40S
Au (355 mg/cm2)
38,40S (E40 AMeV)
Fe (110 mg/cm2)
38S and 40S the first 2 states (tps)
22
BTF at v gt Zv0
low-velocity region vion? Zv0 Eberhardt et
al.Hyp. Int. 3, 195 (1977) Empirical
BTFaZvion/v0 (a Fe 12, a Gd 17)
24MgGd
BTF (kT)
3
2
?
?
1
5
10
15
20
0
Ion velocity v/vion
23
RIKEN-setup for TF experiments

• 6 NaI x 4
• Target AuGd
• Target ladder cooled toT100K
• Coil (Bext 300 Gauss)
• Bext Up Down in every 15 sec.
• 30 plastic scintillators for particle coincidence

liq.N2 container
target ladder
24
Comparison with the systematic
BTF values of 28Si and 24Mg
Mg (Gd)
BTFa Z vion/v0 a12 (Fe) a17 (Gd)
BTF1.2(2) kT
deviation but substantial magnitude
Stopping power gt 4.5 MeV/µm
K.-H. Speidel et al. PLB324(1994)130
25
Recent measurement of ground-state nuclear
moments at RIKEN
26
Production of spin-polarized RI beam with RIKEN
Projectile fragment Separator (RIPS)
RIPS
K540 RIKEN Ring Cyclotron
27
NMR apparatus
ß-NMR w(?)1APcos? (U/D)off
(1AP)/(1-AP) (U/D)on (1- AP)/(1AP) NMR
technique the AFP method
28
Study of the p-shell nuclei through their nuclear
moments
TITech / RIKEN Osaka / 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

Spin-parity assignment
Reduction of E2 effective charges
29
Recent µ-measurements in the sd shell
N20
GANIL
Island of inversion
30
Neutron-rich Al isotopes (theory)
31Al
32Al
33Al
34Al
33Al
Y. Utsuno et al., PRC 64(2001)011301(R)
E. Caurier et al., PRC58(1998)2033

• decreases from 31Al(30Al)?33Al
• E0p0h-E2p2h gt 0 for Al isotopes, but similar to
  Mg, Na, Ne

• 33Al is turning point of the inversion between
  0p-0h and 2p-2h configurations along N20

Al near the border line of Island of Inversion
31
µ-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)
32
Comparison with shell model prediction
Amplitude of intruder configurations is larger
for 32Al ?
In both 30Al and 32Al cases, no disagreement is
observed between µexp and µSM(USD)
H. Ueno et al., Phys. Lett. B 615, 186-192 (2005)
33
Q 32Al (preliminary)
Wide-range scan
Precision measurement
34
Q 31Al (preliminary)
Wide-range scan
Precision measurement
3.5s statistics
35
Summary

• 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 ß-NMR method
  fragment-induced polarization.
• µ-moments enhancement of (sd)2, Jp 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 P1
• Next 33, 35Si, Q(33Al), µ(34,35Al), 33-37P, 33Mg

36
Collaboration

• K. Asahi, M. Takemura, G. Kijima
• K. Shimada, D. Nagae, M. Uchida, T. Arai
• H. Miyoshi, G. Kato, K. Emori, M. Tsukui
• Tokyo 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. Kawamura
• Rikkyo Univ.
• H. Ogawa
• AIST

H. Watanabe Australian National Univ. H. Izumi,
W. Sato, T. Shimoda Osaka University H.
Miyatake, Y.X. Watanabe KEK W.-D.
Schmidt-Ott Universitaet Goettingen G. Neyens,
S. Teughels Leuven