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

Nucleosynthesis G. Martinez-Pinedo

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

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

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

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

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

Penning trap mass measurements close to r-process path

Ion traps at ISOLTRAP precision trap preparation trap precision trap buncher

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)

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)

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

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

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

Mass measurements - plus new cases explored in 2009 Rb 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

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

Comparison: ISOLTRAP vs. JYFLTRAP J. Hakala et al., Phys. Rev. Lett. 101, 052502 (2008) Baruah et al., PRL 101, 262501 (2008)

Major waiting point 80Zn (I) Network calculations by Hendrik Schatz Baruah et al., PRL 101, 262501 (2008)

Major waiting point 80Zn (II) Baruah et al., PRL 101, 262501 (2008)

Limitation: Isomer selection/cleaning Excitation duration required

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

Yield ISOLDE vs. ISOLTRAP

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

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

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

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)

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

Limitation: Isobaric contamination Rb 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

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

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

Electrostatic ion trap layout

Mass separation principle

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

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

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

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

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