Mass Measurements and Nuclear Structure G Bollen National

Mass Measurements and Nuclear Structure G. Bollen National Superconducting Cyclotron Laboratory NSCL Michigan State University Overview and Motivation Mass Measurements at ISOLDE … … and elsewhere Conclusions G. Bollen, INTC-NUPAC Meeting, CERN, Geneva, October 2005

Rare Isotope Physics - an expedition by far not completed! Heaviest Elements? Limit of proton-rich nuclei? Known Nuclei Possible Nuclei Limit of neutron-rich nuclei? Binding energies determine limits of existence G. Bollen, INTC-NUPAC Meeting, CERN, Geneva, October 2005

How do mass measurements contribute? Isospin Symmetry Pairing Exotic decays Fundamental Interactions Stability of SHE s s ce ro p p- r r-p ss e c ro Magic Numbers Evolution of Shell Structure Halos and Skins G. Bollen, INTC-NUPAC Meeting, CERN, Geneva, October 2005

Constraints for nuclear models G. Bollen, INTC-NUPAC Meeting, CERN, Geneva, October 2005

Nuclear Structure and Masses total binding energies Cs two-neutron separation energies Fe 50 56 Systematic study of masses – first indicator of new nuclear structure effects G. Bollen, INTC-NUPAC Meeting, CERN, Geneva, October 2005

Tools for mass measurements on rare isotopes Conventional mass spectrometry CERN-PS + ISOLDE Chalk-River St. Petersburg c o t f. S to u O Time-of-flight spectrometry single turn: SPEG, TOFI multi turn: cyclotrons CSS 2, SARA, storage ring ESR Frequency measurements storage ring ESR/GSI, future NESR, RIBF rings RF transmission spectrometer MISTRAL/ISOLDE Penning traps ISOLTRAP/ISOLDE, LEBIT/NSCL, JYFLTRAP/JYFL, CPT/ANL SHIPTRAP/GSI, TITAN/TRIUMF, MAFFTRAP/Munich + Q-values from reactions and decays G. Bollen, INTC-NUPAC Meeting, CERN, Geneva, October 2005 wc = q/m B k

Comparison of Methods Time-of-Flight TOF Isochronous RF-Spectrometer TOF Schottky Penning Trap LEBIT D. Lunney et al. , Rev. Mod. Phys. 75, 1021 (2003). half life (seconds) G. Bollen, INTC-NUPAC Meeting, CERN, Geneva, October 2005

Mass measurements far from stability at CERN - CERN pioneered direct mass measurements far from stability - Na isotopes (SPS) discovery of island of inversion - 11 Li (SPS) first loosely bound exotic nucleus discovered - Rb isotopes (ISOLDE) first subshell closure observed in long isotopic chains - ISOLDE pioneered new techniques for short-lived isotopes - Penning trap mass spectrometry + many related techniques (ISOLTRAP) - RF mass spectrometry (MISTRAL) G. Bollen, INTC-NUPAC Meeting, CERN, Geneva, October 2005

MISTRAL: Mass measurements at ISOLDE with a Transmission RAdiofrequency spectrometer on-Line transmitted ion signal (counts) RF f = (n + ½) fc fc RF magnet fc 1 m B 505000 505100 505200 frequency (k. Hz) slit 0. 4 mm ion counter ISOLDE 60 k. V beam Resolving Power R= 100000 Sensitivity: 500/s FAST: very short T 1/2 reference beam D. Lunney/Orsay G. Bollen, INTC-NUPAC Meeting, CERN, Geneva, October 2005

Mass measurements of halo nuclei - 11 Li MIS RAL C. Bachelet, Ph. D. thesis (2004), EPJ A direct DOI: 10. 1140/epjad/i 2005 -06 -005 -5 Graphics: I. Tanihata MISTRAL: S 2 n=376(5) ke. V 20% higher than currently used to adjust models. . . G. Bollen, INTC-NUPAC Meeting, CERN, Geneva, October 2005

11 Be, 12 Be, towards 14 Be New Paul-trap Beam cooler Test run (Sept. 2005) : new mass for 12 Be (T 1/2 = 21 ms) MIS RAL G. Bollen, INTC-NUPAC Meeting, CERN, Geneva, October 2005

How magic are magic numbers? SPEG/GANIL H. Savajols et al. , Eur. Phys. J. A direct (2005) DOI: 10. 1140/epjad/i 2005 -06 -189 -6 Island of Inversion MISTRAL: n-rich Na and Mg isotopes with high precision G. Bollen, INTC-NUPAC Meeting, CERN, Geneva, October 2005

ISOLTRAP – triple trap spectrometer PRINCIPLE determination of cyclotron frequency 1 cm B=6 T B = 4. 7 T 5 cm 1 m cooling isobar separation Mass measurement via determination of cyclotron frequency wc = (q/m) B B un c he s, 3 ke. V e ne rg y 60 ke. V ISOLDE- 60 0 00 V ion beam Linear RFQ trap accumulation & bunching of ISOLDE 60 ke. V beam G. Bollen et al. , NIM A 368 (1996) 675 H. Raimbault-Hartmann, NIM B 126 (1997) 378 G. Bollen, F. Herfurth et al. , NIM A 469 (2001) 254 INTC-NUPAC Meeting, CERN, Geneva, October 2005 A. Herlert, K. Blaum

ISOLTRAP harvest In 2002 -2004 131 masses measured ( ) rel. accuracy dm/m 1· 10 -7 mean improvement: factor 40 232 Ra 216 Bi 147 Cs 74 Rb Highlights 2003 / 2004 72 Kr 32 Ar 70 Cu 22 Mg 33, 34 Ar 17 Ne Nuclide Half-life Uncertainty Yield 17 Ne 109 ms ~300 e. V ~1000 / s 22 Na 2. 6 y 160 e. V ~106 / s 32 Ar 98 ms 1. 8 ke. V ~100 / s 72 Kr 17. 2 s 8. 0 ke. V ~1000 / s 74 Rb 65 ms 4. 5 ke. V ~500 / s G. Bollen, INTC-NUPAC Meeting, CERN, Geneva, October 2005

32, 33 Ar - most stringent test of IMME M = a + b. Tz + c. Tz 2 (+ d. Tz 3)? ISOLTRAP 32 Ar T 1/2 = 98 ms Y=100/s 200 180 160 140 d / ke. V Mean TOF (ms) 220 100 80 -40 -30 -20 -10 0 10 20 30 n. RF - 2842679 (Hz) dm = 0. 44 ke. V 32 Ar dm = 1. 8 ke. V 33 Ar A = 33, T = 3/2 quartet: d = -0. 13(45) ke. V A = 32, T = 2 quintet: d = -0. 11(30) ke. V K. Blaum et al. , PRL 91, 260801 (2003) Limits for Scalar Currents from b-delayed p-decay of 32 Ar Motivated by: can be put on purely groundof 32 Ar Search fornow Scalar Currents fromexperimental b-delayed p-decay E. G. Adelberger, A. Garcia et al. , PRL 83 (1999) 1299 and 3101 a = 1. 0050 ± 0. 0052(stat) ± (syst) G. Bollen, INTC-NUPAC Meeting, CERN, Geneva, October 2005

Towards exotic doubly magic nuclei - 78 Ni ISOLTRAP Evolution of nuclear binding towards doubly-magic 78 Ni is not known nuclear structure – r-process C. Guenaut Ph. D 2005 EPJA direct 2005 BRAND NEW 81 Zn Is N = 40 magic? More measurements are required! + n-rich tin isotopes up to 135 Sn G. Bollen, INTC-NUPAC Meeting, CERN, Geneva, October 2005

Identification of triple isomerism in 70 Cu RILIS ISOLTRAP Intensity ratio: 16% 80% 4% (6–) state = gs 101(3) ke. V wc=q/m·B (3–) state = 1. is Unambiguous state assignment! 242(3) ke. V with cleaning of 6– state J. Van Roosbroeck et al. , PRL 92, 112501 (2004) G. Bollen, INTC-NUPAC Meeting, CERN, Geneva, October 2005 1+ state = 2. is

Mass measurement programs outside ISOLDE TRAPS LEBIT NSCL at MSU Fragmentation, In-flight fission Short-lived, non-ISOL elements SHIPTRAP GSI Fusion-Evaporation Superheavies p-rich CPT ANL Fusion-Evaporation Fission p-rich and n-rich (selected regions) JYFLTRAP JYFL IGISOL, Spallation, Fission Non-ISOL elements Storage Ring ESR GSI Fragmentation In-flight fission Schottky (large surveys T 1/2>10 s) TOF: short-lived Spectrometer TOF SPEG GANIL Fragmentation Short-lived, very exotic Cyclotron TOF CSS 2 GANIL Fragmentation Short-lived + reactions (unbound states, beyond the dripline) and decays New projects: TITAN at ISAC (highly-charged ions), MAFFTRAP (n-rich) G. Bollen, INTC-NUPAC Meeting, CERN, Geneva, October 2005

SHIPTRAP – Towards SHE precision measurements with heavy ions produced at SHIP/GSI M. Block/GSI Fusion-evaporation reactions 147 Ho BRAND NEW 146 Ho(#), 147 Ho, 147 Er(#), 148 Er(#), 147 Tb, 147, 148 Dy, 148 Tm(#) G. Bollen, INTC-NUPAC Meeting, CERN, Geneva, October 2005

Low Energy Beam and Ion Trap Facility at NSCL/MSU Precision experiments at low-energies with rare isotopes from fast-beam fragmentation LEBIT ~ 100 Me. V/u ~ 1 e. V 1 cm Gas stopping 9. 4 T Penning trap system Gas stopper Beam Buncher beam from A 1900 Mass measurements Laser spectroscopy Post Acceleration G. Bollen, INTC-NUPAC Meeting, CERN, Geneva, October 2005 Low-energy experiments

Precision Mass Measurement of Fast Beam Fragments Secondary Beam 38 Ca (92 Me. V/u) Statistical uncertainty m(38 Ca++)/m(H 30+) dm 80 e. V Expected final uncertainty dm < 300 e. V • First successful nuclear physics experiment with a thermalized beam from fast beam fragmentation. • 38 Ca is a 0+ beta emitter: new candidate for CVC tests. T 1/2 = 181 ms & … and more to come 37 Ca++ 67 As+ G. Bollen, INTC-NUPAC Meeting, CERN, Geneva, October 2005

Conclusions Mass measurements are key to a better understanding of nuclear structure and important to other fields of research with radioactive isotopes ISOLDE has a very strong mass measurement program - Experiments related to key topics: halos, evolution of shell structure, nuclear astrophysics, fundamental interaction tests - Two excellent experimental devices with significant development potential Complementary programs exist worldwide– different techniques (PTMS, TOF, ESR) – different production methods … still a lot to be done! G. Bollen, INTC-NUPAC Meeting, CERN, Geneva, October 2005

Mass Measurements at RIA-TRAP with 21 Tesla Known masses PTMS dm < 50 ke. V TOFMS dm > 300 ke. V G. Bollen, INTC-NUPAC Meeting, CERN, Geneva, October 2005

Masses close to Z=82 ISOLTRAP Region of shape-coexistence with interesting nuclear structure effects S. Schwarz et al. , NPA 693 (2001) 533 Discussion within IBM & microscopic-macrosopic model R. Fossion et al. , NPA 697 (2002) 703 G. Bollen, INTC-NUPAC Meeting, CERN, Geneva, October 2005