Spin polarization of 23 Ne produced in heavy ion reactions M. Mihara 1, K. Matsuta 1, R. Matsumiya 1, T. Nagatomo 1*, M. Fukuda 1,T. Minamisono 2, S. Momota 3, Y. Nojiri 3, T. Ohtsubo 4, T. Izumikawa 4, A. Kitagawa 5, M. Torikoshi 5, M. Kanazawa 5, S. Sato 5, J.R. Alonso 6, G.F. Krebs 6, and T.J.M. Symons 6 1 Osaka Univ., 2 Fukui Univ. of Technology, 3 Kochi Univ. of Technology, 4 Niigata Univ., 5 National Institute of Radiological Science, 6 LBL * Present address; Univ. of Tsukuba

Introduction Polarized RI beam is extremely useful for studying the structure of unstable nuclei in detail through their nuclear moments ( , Q), fundamental symmetries or interactions in nuclear  decay, material science through the hyperrine interactions, and so on. Projectile fragmentation & Nucleon pickup reactions Heavy ion reactions;

moments T z = –3/2 T z = +3/2 26 Mg → 23 Ne 22 Ne → 23 Ne

Projectile fragmentation Mechanism of polarization (since 1990, Asahi et al.) 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.

Nucleon pickup reaction Momentum mismatch occurrs even at the central region of the momentum distribution. [Groh et al., PRL 90 (2003) 36 Ar + Be → 37 K at 150A MeV v 0 P[ 37 K] ~8.5% near the peak Projectile rest frame

HIMAC NIRS in Chiba, Japan 800 MeV/A

Fragment Separator 26 Mg or 22 Ne 100A MeV HIMAC Polarized 23 Ne Be NaF (T ~15 K) Asymmetry f W(  ) = 1 + AP cos   -NMR system

 -ray time spectra

Polarization and yield of 23 Ne ~4 times larger

Time dependence of polarization T 1 = (140 ) s +240 –100

 -NMR spectra of 23 Ne Y  ~380 cps ~2 hours Y  ~350 cps ~1 day

Magnetic moment of 23 Ne [ 23 Ne in NaF]  = ( ± 3.0) kHz diamagnetic correction :  = 5.7(5)  10 –4  ( 23 Ne)  exp  = ( ± )  N  ( 23 Ne)  old = ( ± )  N Hilmer et al., Z. Naturforsch. 49a (1994) 27 (B ext = 1 T)  ( 23 Ne) SM  = –1.13  N OXBASH

Parallel momentum distributions 1n pickup fragmentation (1p removal) pickup + fragmentation G.A. Souliotis et al.,

Summary Positive spin polarization of 23 Ne was obtained from the single neutron pickup process.  P( 23 Ne)  pickup ~3% >>  P( 23 Ne)  fragmentation ~0.7%.  ( 23 Ne)  = ( ± )  N was obtained. Pickup process is available to produce RNB as well as the projectile fragmentation process.

sigma

23 Ne levels

Precise measurement of  [ 23 Ne] Systematic study of the structure of sd-shell nuclei Reliability check of the shell model calculation Preparation for Q moment measurement Polarized 23 Ne beam Projectile fragmentation Single neutron pickup 26 Mg+Be  23 Ne 22 Ne+Be  23 Ne

Mechanism ; production of polarization (light target) Projectile fragmentation Pickup reaction v > v 0 : P < 0 v 0 36 Ar  37 Groh et al., Phys. Rev. Lett. 90 (2003)

Comparison ExperimentalSchmidtShell Model  23 Ne(–)1.0816(10) * Al(+)3.89(22)  (0) +2.81(22) <z><z> +0.81(58) *Present data Configuration mixing in sd shell