Justus-Liebig-University Giessen Progress on direct mass measurements with the FRS-ESR facilities at GSI Bao-Hua Sun Justus-Liebig-University Giessen Beihang University Introduction Recent research highlights Summary

Motivation of mass measurements Nuclear physics Nuclear astrophysics Others Nuclear Mass M(N, Z) = Z·mp + N·mp - B(N, Z)/c2 Total Binding energies Separation energy, drip-line Shell, subshell, pairing, np pairing Deformation New phenomena: decay mode, halo nuclei New isomer, new isotope Reaction Q-value Test nuclear model or formula … Paths of nucleosynthesis Element abundance … Fundamental interactions and Standard-Model Metrology: fundamental constants, Kg .. …..

GSI Accelerator Facility Today Up to 1000 MeV/u U92+ 2*109 pps SIS 11.4 MeV/u U73+ Ion Sources FRS UNILAC 238U4+ SHIP ESR Velocity filter, fusion, SHIP, SHIPTRAP 20% speed of light Experimental Areas

FRS-ESR facilities — Storage ring mass spectrometry FRagment Separator (FRS) Experimental Storage Ring (ESR) SMS --- Electron cooler Statistic cooling Schottky pick-up Pereira et al., PRC 75, 14602(2007) Primary beams @ 400-1000 MeV/u Projectile fragmentation and fission Cocktail beam or mono-isotopic (selectivity) Highly-charged ions (Rrelativistic energy) In-Flight separation within ~ 500 ns Resolving power 1600@S2, 3300@S4

FRS-ESR facilities FRagment Separator (FRS) Experimental Storage Ring (ESR) B. Franzke, H. Geissel, and G. Münzenberg, H. Wollnik

FRS-ESR facilities FRagment Separator (FRS) Experimental Storage Ring (ESR) SMS --- Electron cooler (dv/v~10-7) Stochastic cooling pick-up Schottky pick-up Litvinov 2003, Chen 2008

FRS-ESR facilities FRagment Separator (FRS) Experimental Storage Ring (ESR) SMS --- Electron cooler Stochastic cooling pick-up Schottky pick-up IMS --- Isochronous mode TOF detector D(m/q)/(m/q)~10% Sun, Knoebel, 2008

Mass surface covered at GSI Large-scale measurements Schottky Mass Spectrometery: Time-resolved, half-live, masses Mass accuracy: 10-30 keV Mass resolving power: 2·106 T1/2 : > 1s Isochronous Mass Spectrometry: First large-scale measurement Mass accuracy: ≈100 keV Mass resolving power: 2·105 T1/2 : ~ 50 s In analysis Masses of more than 1100 Nuclides were measured Ability Broad-band mass measurement (IMS) (SMS) Results: ~ 350 new masses In addition more than 300 improved mass values Y. Litvinov

Outline Introduction Recent research highlights Summary

Neutron-rich nuclides in the element range of Pt – U Chen, Knoebel

Overview of this experiment cold-fragmentation 238U->234Ra nuclear charge exchange reaction: 238Pa, 237Th, 236Ac

New isotope – 224At Single-ion sensitivity b- decay life time Mass determination

Challenge to nuclear theory – new isotopes

Resolved isomer in 133Sb with IMS First large-scale Isochronous mass measurement About 10% in mass-over-charge range: [2.4,2.7] The recorded broad-band revolution time spectrum corresponds to the mass-over-charge range of about 13%. However, it is only possible to analysis 6% due to the limitation of the statistic and the m/q distribution. 485: m/q~2.37 495: m/q~2.47 514: m/q~2.68 B.Sun et al., NPA2008 14

Resolved isomer in 133Sb with IMS First large-scale Isochronous mass measurement About 10% in mass-over-charge range: [2.4,2.7] B.Sun et al., NPA2008 15

Resolved isomer in 133Sb with IMS First large-scale Isochronous mass measurement About 10% in mass-over-charge range: [2.4,2.7] RTOF=60 000 B.Sun et al., NPA2008 16

17 s isomeric state in 133Sb (neutral atom) New half-live domain for storage-ring experiments 17 s isomeric state in 133Sb (neutral atom) Expected half-live of bare isomer: ~ 17 ms, t~991 Genevey et al., EPJA 7, 463 (2000) Sun et al., PLB 688 (2010) 294

Extension of IMS for short-lived isomer investigation “lifetime” in the ring Level scheme As already pointed out, direct gamma radiation from the assumed I = 21/2+ isomer has not been observed in other experiments, and the limit placed on the decay energy is less than 20 keV [11]. The possibility is now addressed that the isomeric state might in fact be the I = 17/2+, 4526 keV state itself [8](See Fig. 4). That state is known [13] to decay by about 98% to the 15/2+ level via a 61 keV M1 transition with a total electron-conversion coefficient of T = 2.5 [27], and 2% to the 15/2− level via a 166 keV E1 transition. If these transitions were to account for the neutral-atom half-life of 17 µs, then the corresponding bare-ion half-life would be Tnuclear = 56 µs. To estimate the center-of-mass survival half-life T for the isomer in the ESR, this should be combined with the Tloss = 68(6) µs survival half-life via T = 1/(1/Tnuclear+1/Tloss), thus yielding an expected overall survival half-life of 31(1) µs. This is not consistent with the measured isomer survival half-life of 58+47 −18 µs (1). For our low statistical measurement, the survival half-life at the 2 confidence level is 58+495 −27 [26] enabling the above hypothesis to be rejected. Therefore, there is another state that leads to the experimental isomer properties. Indeed, there is no problem in understanding the long bare-ion survival time on this basis. The experimental upper limit of 20 keV for the E2 decay of the I = 21/2+ state gives a calculated T = 991. This leads to a bare-ion half-life of about 17 ms (rather than the 17 µs of the neutral atom) which is consistent with the lack of evidence for nuclear decay during the 1 ms observation time.  In support of the shell-model calculation and also complement to the “missing“ information in g-ray spectroscopy

New resonant Schottky pick-up -- fast and sensitive cavity-like Working freq. ~ 245 MHz ( h~125) + separation of Schottky lines: 4 + less time to resolve lines Signal to noise ratio: ~50:1 Detailed, sensitive, fast and highly resolved spectra are a beneficial feature of the new resonant pick up. It opens up new ways to both beam diagonstic and to novel nuclear and atomic physics observations. Freq. Resolution: 5*10-5 (IMS), 8*10-7 (cooler); New resonant schottky only valid in a short range (1MHz) The separation of Schottky lines ∝ the working frequency (a factor of 4); The time it takes to resolve lines is inversely proportional to the measurement harmonic m. (Nyquist theorem) F. Nodeln, et al., NIMA (2011)

New resonant Schottky pick-up Hot Fragments (Iso. Mode)—Broad band Each frame: 320 ms Spectrum of 16 ms Resolving power Setting centered at 213Fr87+ : open slit@FRS, 1 MHz span f/Df~17000

Hot Fragments (Iso. Mode) – Narrow band With this new resonant Schottky pick-up, one could see the momentum dispersion for each particle ..

Outline Introduction Recent research highlights Summary

Summary Ability: mapping nuclear mass surface, new isotopes Single-ion sensitivity: np interaction, decay Resolution: isomeric separation Time-resolved characteristic: life-time measurement New resonant Schottky pick-up: short-lived nuclear mass and lifetime measurements Ability: Mapping nuclear chart, new isotopes

Future -- ILIMA Isomeric beams, LIfetimes and MAsses: The ILIMA project at FAIR Dr. Yuri Litvinov Tuesday, 11 October 2011, 15:45 - 16:10 Status of the Storage Ring Design at FAIR Dr. Sergey Litvinov, Tuesday, 11 October 2011 , 17:05 - 17:30 In future, the intensity upgrade program for the GSI accelerators will substantially contribute to improve the accuracy of the spectroscopy information for the most exotic isotopes and will also give access to more unknown nuclides. The latest results of the general storage ring concept at FAIR will be presented and future perspectives of the ring complex development will be discussed.

FRS-ESR Mass Collaborations G. Audi, K. Beckert, P. Beller, F. Bosch, D. Boutin, T. Buervenich, L. Chen, I. J. Cullen, B. Fabian, T. Faestermann, B. Franzke, H. Geissel, M. Hausmann, P. Kienle, N. Kuzminchuk,O. Klepper, C. Kozhuharov, R. Knöbel, S.A. Litvinov, Yu.A. Litvinov, Z. Liu, L. Maier, J. Meng, G. Münzenberg, F. Nolden, T. Ohtsubo, A. Ozawa, Z. Patyk, B. Pfeiffer, W.R. Plass, T. Radon, M. Reed, H. Schatz, C. Scheidenberger, J. Stadlmann, M. Steck, B. Sun, S. Typel, D.J. Vieira, P.M. Walker, H. Weick, M. Winkler, H. Wollnik, T. Yamaguchi and FRS-ESR collabration