Pushing the boundaries of Penning trap mass spectrometry

Transcription

1 Canada s national laboratory for particle and nuclear physics Laboratoire national canadien pour la recherche en physique nucléaire et en physique des particules Pushing the boundaries of Penning trap mass spectrometry A.A. Kwiatkowski Low-Energy RIB Production by In-Gas Laser Ionization for Decay Spectroscopy RIKEN 9 December 2012 Accelerating Science for Canada Un accélérateur de la démarche scientifique canadienne Owned and operated as a joint venture by a consortium of Canadian universities via a contribution through the National Research Council Canada Propriété d un consortium d universités canadiennes, géré en co-entreprise à partir d une contribution administrée par le Conseil national de recherches Canada

2 Isotope Separator and Accelerator TITAN 20 kev beam transport Mass Separator Target Ion Source Modules 500 MeV protons

3 TRIUMF s Ion Trap for Atomic and RFQ: Accumulates, cools, & bunches beam Design permits forward and reverse extraction of bunched beam Digital RFQ singly charged ions RFQ Nuclear science SCI highly charged ions Measurement Penning trap: 2 c = (q/m) B 3.7 T superconducting magnet hyperbolic precision Penning trap EBIT: ms charge breeding, Q 33+ for 124 Cs Helmholtz-coil configuration for in-trap decay spectroscopy continuous rare isotope beam offline ion source bunched beam for laser spectroscopy Future traps: MR-TOF MS after RFQ (w/ U. of Giessen) Cooler Penning trap before MPET (w/ U. of Manitoba)

4 Cyclotron Frequency Determination send ions ~1/T RF B Inhomogeneous part of magnetic field If rf = c, the ion s energy increases Greater energy shorter time of flight m = m z m q B T RF N Detector

5 The TITAN EBIT superconducting magnet 4 Kelvin, 6 Tesla Helmholtz configuration and drift tube assembly Sikler lens electron collector gun 500mA achieved upgradeable to 5A soon -60kV bias

6 Threshold Charge Breeding Q-value measurement of 71 Ge 71 Ga (SAGE/GALLEX solar- -flux discrepancy); required MPET resolving power for SCI = Laser (TRILIS) on/off and bred to Ne-like charge state ( 71 Ga 21+, 71 Ge 22+ ) for pure ion bunches. MPET resolving power = 20 at Q = 21+ ionization potential (kev) He / K Ne / L Ar M Kr Xe Data1_uranium Data1_xenon Data1_krypton Data1_iron Data1_Argon Data1_oxygen Data1_nitrogen Data1_helium Data1_hydrogen number of electrons M.C. Simon et al., RSI 83 (2012) 02A912, D. Frekers, M.C. Simon, et al., submitted to PRL

7 Threshold Charge Breeding Q-value measurement of 71 Ge 71 Ga (SAGE/GALLEX solar- -flux discrepancy); required MPET resolving power for SCI = Laser (TRILIS) on/off and bred to Ne-like charge state ( 71 Ga 21+, 71 Ge 22+ ) for pure ion bunches. MPET resolving power = 20 at Q = 21+ electron beam 70 ma / 2.0 kv M.C. Simon et al., RSI 83 (2012) 02A912, D. Frekers, M.C. Simon, et al., submitted to PRL

8 Threshold Charge Breeding laser OFF Q = Ga laser ON 71 Ga, 71 Ge Q = Ge Mean TOF [ s] RF [Hz] M.C. Simon et al., RSI 83 (2012) 02A912, D. Frekers, M.C. Simon, et al., submitted to PRL

9 Fastest draw in the West <TOF> [ s] <TOF> [ s] 74 Rb 8+ T 1/2 = 65 ms T RF = 20 ms 11 Li + T 1/2 = 9 ms T RF = 20 ms

10 For faster measurements preparation Penning trap 10s ms (ISOLTRAP, JYFLTRAP, SHIPTRAP) M. Mukherjee et al., EPJA 35 (2008) 1 Lorentz steerer ~ s Goal: (LEBIT, TITAN) measurement times ~ 5 ms for SCI e.g. 14 Be + ~ 10 ms for HCI e.g. 98 In Q+ extraction from gas cell (LEBIT) 10s ms R. Ringle et al., IJMS 263 (2007) 38 (LEBIT) low-energy ISOL 5 ms (ISOLTRAP, TITAN)

11 Removing contamination Dipolar cleaning in Penning trap: Apply dipole excitation at massselective + frequency to eject ions from measurement volume (~10 ms) Time of Flight [ s] Ca RF cent [Hz] Tested for 51 Ca + : Can separate ratios of `good to bad ions 1:200 Implementing SWIFT for broadband cleaning - Spent almost 5 hours identifying contaminants - Principle contaminants were stable 51 V + and unstable 51 Cr + - Possible one low-lying contaminant remained unidentified

12 Removing contamination MR-TOF-IS (spring 2013) R ~ after 2 ms TOF R for mass spectrometry 15 A 230 Purity: At present ~ 1:200 radioactive to contaminant ions With MR-TOF ~ 1:10 4 ratio Capacity 10 4 ions/cycle At max duty cycle of100 Hz, 10 6 pps Efficiency 20% in collaboration with University of Giessen

13 Other TITAN benchmarks Demonstrated sensitivity: Work with 1 ion/bunch Lowest yield measurement 12 Be + 20 yield station Demonstrated (and published) 3 ppb systematic uncertainty Highest charge states Stable mass measurement Q = 25+ for 84 K Unstable mass measurement Q = 22+ for 71 Ge Achieved Q = 33+ for 124 Cs

14 TITAN roadmap Production: ISOL chemically independent Speed: SCI 9 ms 5 ms HCI 65 ms 10 ms Purity: dipole 1:200 pure MR-TOF 1:10 4 Sensitivity: 12 Be + 20 pps (@ yield station) high(er) yields

15 Canada s national laboratory for particle and nuclear physics Laboratoire national canadien pour la recherche en physique nucléaire et en physique des particules Thank you! TRIUMF: Alberta British Columbia Calgary Carleton Guelph Manitoba McMaster Montréal Northern British Columbia Queen s Regina Saint Mary s Simon Fraser Toronto Victoria Winnipeg York Giessen Merci C. Andreoiu, J.C. Bale, T. Brunner, A. Chaudhuri, U. Chowdhury, A.T. Gallant, A. Grossheim, AAK, A. Lennarz, T.D. Macdonald, E. Mane, M.R. Pearson, B.E. Schultz, M.C. Simon, V.V. Simon, J. Dilling and TITAN collaboration Owned and operated as a joint venture by a consortium of Canadian universities via a contribution through the National Research Council Canada Propriété d un consortium d universités canadiennes, géré en co-entreprise à partir d une contribution administrée par le Conseil national de recherches Canada