1. 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

2. 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 ..
…..

3. 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

4. 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 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

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

6. 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

7. 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

8. Mass surface covered at GSI
Large-scale measurements
Schottky Mass Spectrometery:
Time-resolved, half-live, masses
Mass accuracy: 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

9. Outline
Introduction
Recent research highlights
Summary

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

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

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

13. Challenge to nuclear theory – new isotopes

14. 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

15. 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

16. 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. 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

18. 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
−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

19. 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)

20. 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 1 MHz span
f/Df~17000

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

22. Outline
Introduction
Recent research highlights
Summary

23. 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

24. Future -- ILIMA
Isomeric beams, LIfetimes and MAsses: The ILIMA project at FAIR
Dr. Yuri Litvinov
Tuesday, 11 October 2011, 15: :10
Status of the Storage Ring Design at FAIR
Dr. Sergey Litvinov,
Tuesday, 11 October 2011 , 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.

25. 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