26th jan. 2010physics of nuclei at extremes, tokyotech1 recent activities with slow and stopped ri...

26th Jan. 2010 Physics of Nuclei at Extremes, TokyoTech 1

Recent activities with slow andRecent activities with slow andstopped RI at Tohoku-Cyclotronstopped RI at Tohoku-Cyclotron

Cyclotron and Radioisotope Center (CYRIC), Tohoku Univ.:K. Shimada, S. Hoshino, S. Izumi,H. Ouchi, A. Sasaki, T. Wakui, T. Shinozuka,

RIKEN: Y. Miyashita

KUR: M. Tanigaki

JAEA: M. Asai, N. Sato

TOHOKUUNIVERSITY

International Workshop on Physics of Nuclei at Extremes, Jan. 2010, TokyoTech

1.Introduction of CYRIC2.Production of medium- heavy

neutron-rich nuclei1. RF Ion-guide ISOL

3.Recent results1. half life of 103mTc and

105mRu2. g-factor of 109mRh and 132mI


A

B

2

110

9

8

7

6

4

53

A AVF Cyclotron (K=110 MeV)B HM12 Cyclotron (production of positron emitters for PET)1 RI production3 High-intensity fast neutron

(Ep = 20-80 MeV 、 E = 1 MeV 、 106 n/cm2sA)

4 Large acceptance -ray detector array (Hyperball2) (6 Clover type ＋ 14 Single type)

5 Heavy-ion irradiation (in air)7 Material irradiation8 High-resolution beam line and large scattering chamber9 Charged particle radiation therapy10 Beam swinger and Large solid angle neutron detection system

Slow RIB facility

2 RF ion-guide isotope separator on-line (RFIGISOL)

6 Surface ionization ion source for electron EDM measurement

Cyclotron and Radioisotope Center (CYRIC), Tohoku University

Cyclotron facility


Purpose and backgroundNuclear structure of the medium-heavy neutron-rich nuclei

Life times and B(E2) of isomers Nuclear moments

Independent of nuclear structure model Single-particle energies and configurations of wave function

Known magnetic moments

N=50 N=82

Z=50

Z=28

Stable

(Sn)

(Ni)

High-melting point↓

hardly produced byISOLDE type ISOL

↓Development of

RFIGISOL(BigRIPS, FRS)

100Zn

132Sn


Comparison of RI Production methods

Projectile-fragment separators In-flight A primary beam > A 2ndary beam

ISOL (⊃ RFIGISOL) A primary beam<<A 2ndary beam<A target

Target fragmentation Fission of 238U etc.

⇒ Middle-heavy neutron-rich nuclei

RFIGISOL High-melting-point and short-life RI⇒


Correction of fission products with gas

Stop, thermalization and ionization ISOL: Thermal diffusion and surface ionization RFIGISOL: Large He gas volume and avoidance of

neutralization Independent of chemical properties Highest ionization energy of He

How are the fission products collected to the nozzle?

300 mm

20

0 m

m

Exit hole1 mm

U target

Fission products

3-kPa He

Gasstream DC field

RF field

RFIGISOLISOL

~3000K

U target

Proton

Proton

Recoil with several MeV

Recoil, ~MeV

=Ion+

+Ionizer


Φ220 mmΦ220 mm

exit hole1.2 mm

Base film: 50-μm-thick kaptonElectrodes: 360 rings at 0.6-mm intervals

EDC

ERF

Track of ions

RF electrodes (RF carpet)

y

x

Trapping potential(for ion in resonance)

x

y RF phase

originally developed by M. Wada, RIKEN


Typical parameters of RFIGISOL

Target: natural Uranium(Effective thickness:

190 mg/cm2)

Stop and thermalization: He gas (3 kPa), ~104 cm3

Guide: DC field(~5 V/cm)

Giude: RF field(~3 MHz, ~50 Vpp)

Extraction: Gas jet +DC field (~1 kV)

Mass spectrometer

Proton beam(50 MeV, 1 A)

Acceleration: DC 30 kV

CYRIC2nd target room

m


Photo ～ RFIGISOL chamber

proton

Acceleration: DC 30 kV

U target

He gas: 3 kPaDC field: 5 V/cmRF field: 3 MHz,50 Vpp

Massspectrometer


112Rh ~4000112Ru ~400

100Nb ~1300100Zr ~1300100Y ~400

91Rb ~400

80As ~20080Ge ~200

119Cd ~800119Ag ~400

78Ni

Fission production

cross section

Yields with RFIGISOLPrimary beam: Proton, 50 MeV, 1 μAYield at beam-line end, after passing mass spectrometer Stable line

107Tc ~2400 107Ru ~4600

[particles/sec]

109Tc ~1300 109Ru ~1300

111Tc ~1100 111Ru ~7100?

114Pd ~9000

Bold: 2009Normal: 2007

105Tc ~2400

100Zr

132Sn

10 mb

1 mb

0.1

125Pd (BigRIPS)

ObtainedYields

∝Expected Yields

132Te ~1000

Recent experimentsT1/2: 103mTc, 105mRu

g-factor: 109mRh, 132mI


Recent experiments (1)Life-time measurement


Setup of life-time measurement

Beam monitor (co-axial Ge)1. Implantation: ~1τ

2. Transfer ： ~5 s

3. Measurement: ~1τ

Detectors for life-time measurement

good time resolutionPlanar Ge: ~1 nsBaF2: ~0.01 nsSystem: 5 ns

good energy resolution

10-ns isomers→Measurable


Preliminary results– 163.74 keV : 55 ns → ~18 ns– 246.26 keV : ~15 ns

1ch = 0.25 nsec

105Ru103Tc

[Y. Miyashita, Tohoku Univ. / RIKEN][K. Shimada, H. Ouchi, Tohoku Univ.]

Preliminary result– 83.38 keV : ~40 ns

Recent experiments (1) Life of Isomer

(5/2-,3/2-)

3/2+,5/2+

(5/2)+


Recent experiments (2)g-factor measurement


Time differential Perturbed Angular Correlation methods (TDPAC)

...)(cos1)( 222 PAW

)()exp(),( 0 tWT

tNtN L

)2cos(4

3

),90(),180(

),90(),180()(

L22 tA

tNtN

tNtNtR

det. 10°

det. 290°

det. 3180°

° intensity distribution

extBg N

L

Bext

tL

T1

2


Ge detectors

Magnet(0.34 T)

[Y. Miyashita, Tohoku univ. / RIKEN]On-line TDPAC method(Time differential perturbed angular correlation)

Tape transport system Detection system

g = 0.78 + 0.17 - 0.03 [N]

BaF2 detectors

Tape

TDPAC spectrum

B = 0.34 T

(2) g-factor in 109mRh (Ex=225.98 keV, T1/2=1.66 ms)


I=3/2+ I=5/2+ I=3/2+ I=5/2+

(2+) ⊗(g9/2)93Nb 4.9483(3) 4.8049(2) (4+) ⊗(g9/2)93Nb 2.2496(1) 2.8773(1)

(2+) ⊗(g7/2)123Sb 1.4781(2) 1.8672(2) (4+) ⊗(g7/2)123Sb 0.57899(1) 1.22493(2)

(2+) ⊗(d5/2)141Pr 2.3047(3) 3.1587(2) (4+) ⊗(d5/2)141Pr -1.3430(3) 0.55323(4)

(2+) ⊗(d3/2)169Tm 0.871(2) 0.586(2) (4+) ⊗(d3/2)169Tm 3.294(19) 2.317(5)

(2+) ⊗(s1/2)193Ir 0.4561(1) 0.5389(2) (4+) ⊗(s1/2)193Ir 1.9024(10) 1.5719(3)

I=3/2+ I=5/2+

1.17 +0.23+0.03. 1.95 +0.38+0.05 - 0.02 - 0.03 - 0.03 - 0.05

or

1

111

21

111

2gI II

IIjjg

II

IIjjgCCcCCj

magnetic moment

109Rh 225 keV statesimple single-particle + excited-core coupling a proton core: excited 2+ or 4+ in 108Ru

1g9/2, 1g7/2, 2d5/2, 2d3/2, 3s1/2

of single-particle ground state

Magnetic moments


( Bhf = +26.5 ±0.5 T )PAC spectrum in the Ni foil

Magnetic moment in 132mI

= +(2.06 ± 0.18)NBaF2 detectors×3

Tanigaki, PRC80(2009)034304


Comparison of a simple jj-coupling model of odd-odd nucleus

(N) Ref.Experiment +2.06 ± 0.18 This work +2.22 ± 0.30 Singh et al. by TIPACCalculation (g7/2)(d3/2)−1 +2.40 (d5/2)(d3/2)−1 +2.83

Values for empirical g factors (g7/2) +2.80 Av. 131,133I (d5/2) +2.81 Av. 129,131I (d3/2)−1 +0.75 Av. 131Te, 133Xe

←proton-odd

←neutron-odd

odd-odd nucleus is described based on a jj-coupling model

)1(2

)1()1()(

)(2

1),(

I

jjjjgg

IggNZ

nnppnp

np


SummaryCYRIC facility

2 cyclotrons and 10 beam lines Production of RI beam using RFIGISOL

RFIGISOL ISOL specified for high-melting-point and short-

life nuclei Large He gas buffer and RF carpet

Recent results life-time ： 105mRu ， 103mTc

Planar Ge-BaF2 system g-factor and μ ： 109mRh ， 132mI

TDPACNext plan: g-factor of 105mRu


Thank you for your attention

26th jan. 2010physics of nuclei at extremes, tokyotech1 recent activities with slow and stopped ri...

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