Laser Spectroscopy of Cadmium Isotopes: Probing the Nuclear Structure Between the Neutron 50 and 82 Shell Closures

D. T. Yordanov Max-Planck-Institut für Kernphysik, Heidelberg, Germany for the COLLAPS Collaboration

P 271, INTC, Nov 2009 Chart of Nuclides 50 A decade of collinear laser spectroscopy 82 at ISOLDE

Monopole migration Ga Cu Spherical Shell Model 50 Z 28 1g 50 50 9/2 2 40 N p1/2 2p 1f5/2 38 20 2p3/2 32 1f 28 1f7/2 28 20 Island of inversion 1d3/2 20 28 2 s 2s 16 8 Na Mg 1d 20 1d5/2 14 8 2 Ne 1p 8 1 1/2 8 Be Halo nuclei p 2 1p3/2 6 2 Li 1s 1s 2

P 271, INTC, Nov 2009 Chart of Nuclides 50 A decade of collinear laser spectroscopy 82 at ISOLDE

Monopole migration Ga Cu Spherical Shell Model 1 92 Z 28 h9/2 50 N 82 20 1h

1h11/2 82 28 Island of inversion 3s 3s1/2 70 2d 68 8 Na Mg 3/2 20 2d 2d5/2 64 2 Ne 1g7/2 58 8 Be Halo nuclei 2 1g 50 Li 1g9/2 50

P 271, INTC, Nov 2009 Survey of nuclear moments in the Z ≈ 50 region, Interest in the cadmium isotopes

132 Sn 98 Cd 100 Sn

130 Cd

rp process, steady state r process

P 271, INTC, Nov 2009 Interest in the even - even cadmium isotopes

Shape transition at 130 Cd? Detection via the change radii.

P 271, INTC, Nov 2009 Physics interest in the odd - A isotopes

prolate 105 - 109 Cd oblate 107 - 115 Cd

• Spins and magnetic moments in the range 100 < A < 130 • shape coexistence from the quadrupole moments and the isomer shifts

P 271, INTC, Nov 2009 Astrophysical aspects

132 Sn 98 Cd 100 Sn

130 Cd

rp process (steady state) r process expectations for more accurate theoretical lifetimes of the N=82 isotones below 129 Ag

P 271, INTC, Nov 2009 Experimental method

COLLAPS 1.) ion beam; 2.) laser; 3.) deflection plates; 4.) post acceleration; 5.) optical detection

accumulation

release ISCOOL - ISOLDE RFQCB

4 T2 ≈ T 1 / 10

P 271, INTC, Nov 2009 Spectroscopic transitions Ionization energy 9 eV 2 3 5p P3/2 5s6s S 1 6.4 eV 2 the ion 5p P1/2

D1 D2

4 eV 3 5s5p P2 3.8 eV 3 3 5s5p P0 5s5p P1 3.7 eV

2 the atom 5s S1/2

Benefits in respect to the atom: 2 1 • No charge exchange - intensity gain × 2; 5s S0 • No meta stable states - intensity gain × 4; • No pumping out into dark states; • × 5 stronger transitions; Benefits in respect to the ion: • 30% quantum efficiency (14% in the atom); • Higher sensitivity to the nuclear spin (Higher J); Wavelengths: Wavelength: • Ar + laser + Stilbene 3 + frequency doubling; • Ar + laser + Coumarin 521 (Coumarin 334);

P 271, INTC, Nov 2009 Yields of cadmium N = 82 N N = 50 N C µ µ feasibility limit with ISCOOL ions/ UC + RILIS (PSB)

LaC + RILIS (PSB) molten Sn (SC)

100 Cd accessible range 130 Cd

P 271, INTC, Nov 2009 Beam contamination and purification methods

• Surface ionized Isobaric contamination: - Indium - Cesium and Barium (proton-rich isotopes near A=130 from spallation) - Molecular beams

• Quartz transfer line: - suppression of indium: In/Cd < 2%, tests on UC#362 (CERN-INTC-2008-036 / INTC-CLL-003) - suppression of cesium: 130 Cs < 10 6 ions/ µµµC, tests on UC#338

• Neutron converter: - reduction of cesium with a factor of 100, tests with UC#183; - reduction of cadmium with a factor of 3 to 10;

• Microgating with the pulse-repetition of RILIS

P 271, INTC, Nov 2009 Spectroscopy on intense continuous beams N = 82 N N = 50 N C µ µ ions/ UC + RILIS (PSB)

LaC + RILIS (PSB)

molten Sn (SC)

106-120 Cd, UC target + RILIS + GPS, 8 shifts

P 271, INTC, Nov 2009 Bunched spectroscopy: N-deficient isotopes N = 82 N N = 50 N C µ µ ions/ UC + RILIS (PSB)

LaC + RILIS (PSB)

molten Sn (SC)

100-105 Cd, LaC target + RILIS + HRS, 9 shifts

P 271, INTC, Nov 2009 Bunched spectroscopy: N-rich isotopes N = 82 N N = 50 N C µ µ ions/ UC + RILIS (PSB)

LaC + RILIS (PSB)

molten Sn (SC)

121-130 Cd, UC target + RILIS + HRS, 2 × 9 shifts

P 271, INTC, Nov 2009 BEAM-TIME REQUEST for measuring spins, rms charge radii, magnetic and quadrupole moments of ground and isomeric states in the isotopes of cadmium

• Intense beams: 106-120 Cd, UC target + RILIS + GPS, 8 shifts

• N-deficient: 100-105 Cd, LaC target + RILIS + HRS, 9 shifts

• N-rich: 121-130 Cd, UC target + RILIS + HRS, 2 × 9 shifts

TOTAL: 35 shifts

P 271, INTC, Nov 2009