1. Alexander Herlert, CERN (PH-SME-IS)
Mass measurements on
neutron-rich nuclei at ISOLTRAP:
Present status and future perspectives
Alexander Herlert, CERN (PH-SME-IS) B +
q/m
1st EURISOL UG topical meeting December 9-11, 2009

2. Nucleosynthesis
G. Martinez-Pinedo

3. Mass values for astrophysics calculations
Experiments
Astrophysics
calculations
data
Atomic mass
evaluation
mass
values
mass
extrapolations
Mass
models

4. Extrapolation – limitation of mass models?
David Lunney (ENAM 1995)

5. Mass accuracy – AME2003
G. Audi, A.H. Wapstra, C. Thibault, Nucl. Phys. A 729

6. Penning traps for mass measurements on short-lived nuclides
JYFLTRAP
 Jyväskylä
TITAN
SHIPTRAP
LEBIT
GSI 
 TRIUMF
CERN 
 MSU
Argonne
CPT
ISOLTRAP 6

7. Relative mass uncertainty vs. half life
dn/n=10-8
T1/2=100ms
David Lunney
(ENAM2008)

8. Penning trap mass measurements close to r-process path

9. Ion traps at ISOLTRAP precision trap preparation trap precision trap
buncher

10. determination of cyclotron frequency
Mass purification - isobaric separation
determination of cyclotron frequency
(R = 107)
HRS CO
B = 5.9 T
removal of
contaminant ions
(R = 105)
Number of ions N2
Bunching of the
continuous beam
B = 4.7 T
Cyclotron frequency / Hz
Buffer gas cooling with QP excitation:
Savard et al., Phys. Lett. A 158, 247 (1991)
M. Mukherjee et al., EPJA 35, 1 (2008)

11. determination of cyclotron frequency
ISOLTRAP measurement trap B +
q/m
determination of cyclotron frequency
(R = 107)
B = 5.9 T
removal of
contaminant ions
(R = 105)
Bunching of the
continuous beam
B = 4.7 T
M. Mukherjee et al., EPJA 35, 1 (2008)

12. Cyclotron frequency determination
fit of theoretical line
shape to the data
out of resonance
in resonance

13. Principle of mass determination
cyclotron frequency
of "unknown" nuclide
cyclotron frequency
of well-known nuclide
determination of mass ratio

14. Mass accuracy – AME2003 Rb Kr Br Se As Ge Ga Zn Cu Ni Co Fe Mn Cr V TiCa Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Rb Kr

15. Mass measurements - plus new cases explored in 2009Rb Kr Br Se As Ge Ga
New VADIS
ion source Zn Cu Ni Co Fe Mn Cr
ISOLTRAP 2009 V Ti
ISOLTRAP
JYFLTRAP
New Mn RILIS
scheme Sc Ca K

16. Two-neutron separation energies of Kr isotopes at N=60Nb Zr Tc Y Mo Sr Kr

17. Comparison: ISOLTRAP vs. JYFLTRAP
J. Hakala et al.,
Phys. Rev. Lett.
101, (2008)
Baruah et al., PRL 101, (2008)

18. Major waiting point 80Zn (I)
Network calculations by Hendrik Schatz
Baruah et al., PRL 101, (2008)

19. Major waiting point 80Zn (II)
Baruah et al., PRL 101, (2008)

20. Limitation: Isomer selection/cleaning
Excitation duration required

21. Limitation: Ion yieldsRb Kr Br Se As Ge Ga Zn Cu Ni Co Fe Mn Cr V Ti Sc Ca
ions / mC K

22. Yield ISOLDE vs. ISOLTRAP

23. Limitation: Half-life of short-lived nuclidesK Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Rb Kr

24. Krypton yields and ion yield needed for mass measurements
efficiency = 1%

25. Limitation: Isobaric contamination
GPS
m/Dm ~ 1000
HRS
m/Dm ~ 5000

26. Mass separation in Penning trap
HRS CO
removal of
contaminant ions
(R = 105)
Number of ions N2
B = 4.7 T
Cyclotron frequency / Hz
Buffer gas cooling with QP excitation:
Savard et al., Phys. Lett. A 158, 247 (1991)
G. Bollen, et al., NIM A 368, 675 (1996)
F. Herfurth, et al., NIM A 469, 264 (2001)

27. Space-charge effects: 85,87Rb
Summer Student
project 2009:
Christian
Holm Christensen

28. Limitation: Isobaric contaminationRb Kr Br Se As Ge Ga Zn Cu Ni Co Fe Mn Cr V
Applied quartz
transfer line
for Zn measurements Ti Sc Ca
ions / mC K

29. Need new techniques: Quartz transfer line
cooled
transfer line
temperature
controlled
suppression of
alkali ions
E. Bouquerel et al.

30. Possible solution: Electrostatic ion trap
Test-setup at University Greifswald in operation
To be shipped and installed at ISOLTRAP during the 2009/2010 shutdown
Robert Wolf

31. Electrostatic ion trap layout

32. Mass separation principle

33. Time-of-flight gating and ion removal
N2 vs. CO
Bradbury-Nielsen-Beamgate
OFF

34. Time-of-flight gating and ion removal
N2 vs. CO
Bradbury-Nielsen-Beamgate ON

35. Installation at ISOLTRAP 2009/2010
4th ion trap at ISOLTRAP !

36. Summary Penning traps allows one to obtain accurate and precise
mass values of short-lived isotopes
Limitation due to purity, yield, and half-life
Recent developments at ISOLDE:
ISCOOL RFQ buncher and cooler – lower beam emittance
Quartz transfer line target – better beam purity
New VADIS arc discharge ion source – higher ionization efficiency
New RILIS lasers and schemes – higher ionization efficiency
Recent developments at ISOLTRAP:
Ramsey type excitation – faster measurement
New electrostatic ion trap – faster purification and contamination suppression
New ion detectors – higher detection efficiency

37. Thanks to ... The ISOLDE Collaboration and the ISOLDE technical group
G. Audi, S. Baruah, D. Beck, K. Blaum, Ch. Böhm,
Ch. Borgmann, M. Breitenfeldt, B. Cakirli, P. Delahaye,
M. Dworschak, S. Eliseev, D. Fink, S. George, C. Guénaut,
U. Hager, F. Herfurth, A. Kellerbauer, H.-J. Kluge,
M. Kowalska, S. Kreim, D. Lunney, M. Marie-Jeanne,
M. Mukherjee, S. Naimi, D. Neidherr, Y. Novikov,
M. Rosenbusch, R. Savreux, S. Schwarz, L. Schweikhard,
Ch. Weber, U. Warring, R. Wolf, C. Yazidjian, K. Zuber
The ISOLDE Collaboration and the ISOLDE technical group