Spin polarization of 23Ne produced in heavy ion reactions

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Spin polarization of 23Ne produced in heavy ion
reactions

• M. Mihara1, K. Matsuta1, R. Matsumiya1,
• T. Nagatomo1, M. Fukuda1,T. Minamisono2,
• S. Momota3, Y. Nojiri3, T. Ohtsubo4,
• T. Izumikawa4, A. Kitagawa5, M. Torikoshi5,
• M. Kanazawa5, S. Sato5, J.R. Alonso6, G.F.
  Krebs6, and T.J.M. Symons6

1Osaka Univ., 2 Fukui Univ. of Technology,
3Kochi Univ. of Technology, 4Niigata Univ.,
5National Institute of Radiological Science,
6LBL Present address Univ. of Tsukuba
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Introduction
Polarized RI beam
is extremely useful for studying
the structure of unstable nuclei in detail
through their nuclear moments (m, Q),
fundamental symmetries or interactions in
nuclear b decay, material science through the
hyperrine interactions, and so on.
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moments
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Projectile fragmentation
(since 1990, Asahi et al.)
Mechanism of polarization
Because of the Fermi motion and deflection
(Coulomb or nuclear force), polarization can be
obtained by selecting the parallel momentum and
deflection angle of fragments.
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Nucleon pickup reaction
_at_MSU 36Ar Be ? 37K at 150A MeV
Groh et al., PRL 90 (2003) 202502
P37K 8.5 near the peak
Momentum mismatch occurrs even at the central
region of the momentum distribution.
v lt v0 P gt 0
Projectile rest frame
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HIMAC
NIRS in Chiba, Japan
800 MeV/A
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Fragment Separator
HIMAC
26Mg or 22Ne 100A MeV
Be
Polarized 23Ne
b-NMR system
W(q) 1 AP cosq
NaF (T 15 K)
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b-ray time spectra
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Polarization and yield of 23Ne
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Time dependence of polarization
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b-NMR spectra of 23Ne
Yb 350 cps 1 day
Yb 380 cps 2 hours
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Magnetic moment of 23Ne
n23Ne in NaF (3296.4 3.0) kHz
(Bext 1 T)
diamagnetic correction s 5.7(5) 104
m(23Ne)exp (1.0816 0.0010) mN
m(23Ne)old (1.0795 0.0010) mN
Hilmer et al., Z. Naturforsch. 49a (1994) 27
m(23Ne)SM 1.13 mN
OXBASH
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Parallel momentum distributions
_at_MSU
G.A. Souliotis et al., PRC46(1992)1383
1n pickup
fragmentation (1p removal)
pickup fragmentation
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Summary

• Positive spin polarization of 23Ne was obtained
  from the single neutron pickup process.
• P(23Ne)pickup 3 gtgt P(23Ne)fragmentation
  0.7.
• m(23Ne) (1.0816 0.0010)mN was obtained.
• Pickup process is available to produce RNB as
  well as the projectile fragmentation process.

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sigma
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23Ne levels
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Precise measurement of m23Ne
Systematic study of the structure of sd-shell
nuclei
Reliability check of the shell model
calculation Preparation for Q moment measurement
Polarized 23Ne beam
26MgBe 23Ne
Projectile fragmentation
Single neutron pickup
22NeBe 23Ne
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Mechanism production of polarization (light
target)
Projectile fragmentation
v gt v0 P lt 0
Groh et al., Phys. Rev. Lett. 90 (2003) 202502
36Ar 37K _at_MSU
Pickup reaction
v lt v0 P gt 0
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Comparison lt?gt
Experimental Experimental Experimental Schmidt Shell Model
? 23Ne 23Ne ()1.0816(10) ()1.0816(10) -1.91 -1.13
? 23Al 23Al ()3.89(22) ()3.89(22) 4.79 3.94
?(0) ?(0) ?(0) ?(0) 2.81(22) 2.88 2.81
lt?zgt lt?zgt lt?zgt lt?zgt 0.81(58) 1 0.82
Present data
Configuration mixing in sd shell