TRIUMF The TITAN EBIT: Status & Research Plans

Transcription

1 The TITAN EBIT: Status & Research Plans A. Lapierre, T. Brunner, C. Champagne, P. Delheij, and J. Dilling for the TITAN collaboration Canada s National Laboratory for Nuclear and Particle Physics, Vancouver, British Columbia, Canada

2 Outline TITAN : High-Precision Mass Measurements. TITAN EBIT. Role of the EBIT in Mass Measurements. Status Trap & Beam Physics Plans and Ideas. Nuclear & Atomic Physics Plans and Ideas. Summary. EBIS/T /26

3 First a Bit of History Build at the MPI-K: , Shipped to : April 2006 National Nuclear Research Lab., Vancouver, BC, CANADA CA Rare-isotope beam facility (500-MeV proton cyclotron) GE August 2006 September 2006 EBIS/T /26

4 TITAN Facility 2 Wien filters: q/m selection Under development (proton cooling) Aq+ A+ <5 kv q EBIT is a part of the TITAN facility. TITAN: s Ion Trap for Atomic and Nuclear Physics. Motivation: High-precision mass <60 kev measurements of short-lived isotopes (T1/2~10 ms) for nuclear physics ( m/m<10-8). A+ Short-lived isotopes from an Isotope Separator and Accelerator (ISAC). EBIS/T 2007 Consists of 4 ion traps. EBIT is used as a charge breeder for higher precision of mass measurement. 4/26

5 TITAN Platform! Penning trap RFQ HV platform EBIT HV platform EBIT RFQ EBIS/T /26

6 TITAN EBIT High-voltage platform 60 kv high-voltage duct Beam line under construction Magnet / Trap Injection Extraction Electron gun (CF200 cube) Electron collector (CF200 cube) TESLA or FLASH EBIT twin 3 m EBIS/T /26

7 TITAN EBIT High-voltage platform High-voltage cage ~2.5 m ~1 m EBIS/T /26

8 Cut of TITAN EBIT Cryogen-free superconducting coils Sikler lenses Working parameters: Max. e-beam energy: ~70 kev Max. e-beam current: 500 ma (up to 5 A) Max. magnetic field strength: 6 T Current density (center): A/cm 2 Retractable e-gun Magnetic-field distrib. Electron collector _ Up to ~60 kv Trap + Electron gun _ 0 to ~10 kv Up to ~60 kv Dip ~460 mm ~235 mm EBIS/T /26

9 Sikler lens A Sikler lens is an Einzel lens whose central electrode is segmented into 4 electrodes to steer the beam. 2 diagonal cuts EBIS/T /26

10 Electron Gun Trimming coil Soft iron Bucking coil To suppress main field 500 ma cathode; R1.7 mm Gun perveance: 0.2 µa / V 3/2 Cooling water hoses & electrical feedthroughs not shown Anode Focus electrode Dispenser cathode (Pierce geometry) 175 mm EBIS/T /26

11 Trap Coils (NbSn 3 ~4 K Thermal ~30 K Electron gun 77 mm 272 mm Center electrode segmented into 8 independent sections: Rotating-wall cooling Side-band cooling Ion Cyclotron Resonance Trap made of 9 drift tubes Be windows (7 access viewports) EBIS/T /26

12 Cryogen-Free Superconducting Magnet EBIS/T /26

13 Collector coil (to suppress main field) Electron Collector Heat-exchanger fins (cooling water) Extractor elec. Suppressor elec. e-beam V acc V acc -200 V V acc -200 V Shields 174 mm EBIS/T /26

14 Gas Injection 2 differentially pumped chambers Mike Froese Master s thesis EBIS/T /26

15 Role of the EBIT in Mass Measurements TITAN Penning trap: Hence, the precision of mass measurements is a function of the ion charge state, q. δm m T obs m qb N 3 hyperbolic electrodes producing a quadrupole potential well. Mass measurements in a Penning trap are performed by measuring ion cyclotron frequencies. Conclusions: For a fixed observation time, mass measurements with higher charge states are more accurate. v c 1 = 2 π q m B EBIT is used as a charge booster! EBIS/T /26

16 As an Example He-like 74 Rb (T 1/2 =65 ms) 2x10-8 q=1e 6x10-10 δm/m increases by a factor of q=35 q=35e EBIS/T /26

17 Charge Breeding Time Reacheable TITAN EBIT Parameters For mass measurements on short-lived isotopes, a rapid production of HCI is crucial! CB time < Half Life of Nuclei ~400 ma He-like Kr 74 Rb half-life: 65 ms He-like 74 Rb CB time:~10 ms Bare 74 Rb CB time: ~100 ms Ar, τ~10 ms With a 5-A cathode, bare 74 Rb could be produced within ~10 ms Mike Froese Master s thesis (Becker s SUK program) EBIS/T /26

18 TITAN EBIT Status Sep. 2006: Reached a beam current ~400 ma (~7 kev) & energy of ~20 kev (~172 ma). Sep. 2006: Collector shorted. Nov. 2006: Received a spare collector from Jose. June 2007: New collector just installed! Meanwhile building an injection/extraction beam line based on SIMION simulations. Instances from S. Schwarz Quadrupole triplet Beam line under construction EBIS/T /26

19 Present Work Installation of an injection/extraction beam line. Installation of a ion source for injection. Remote control of all vacuum systems and EBIT power supplies: MIDAS & EPICS Installation of an event-mode DAQ system. 2-way Daly-type beam imaging system (w/ no moving parts) C. Leung, Undergrad. summer student EBIT SIMION simul. Secondary electrons RFQ Good representation of ion beams! MCP+P screen Ions CCD camera EBIS/T /26

20 Research Plans: Trap & Beam Physics Emittance measurements and optimization Transverse emittance Longitudinal emittance ε = π r r'[mm mrad] = E T[eV s] t ε l di dv I Energy spread C. Champagne, MSc candidate V MCP V Studies and optimization of charge breeding, extraction, and injection EBIS/T /26

21 Research Plans: Electron Capture Branching Ratios Measurements of electron capture branching ratios of nuclei in singly charged ions through x-ray detection. Radioactive singly charged ions trapped in the Penning-trap mode: no electron beam used! EC branching ratios used to evaluate double β and neutrinoless double β decay nuclear matrix elements. If 0νββ decay is observed, EC branching ratios can be used to infer the neutrino mass. Nuclear decay X-ray p + e - n + ν e β-decay electrons are used to monitor trapped radioactive ions. First candidate Technetium MeV electrons of an emission pitch angle >80 o are trapped. 3.7 T 3.5 T θ=80 o T. Brunner, PhD candidate 1 v = tan( θ) v // Crit = B B max min 1 Trapped electrons SIMION simul. EBIS/T /26

22 Research Plans: EBIT for AMS AMS: Accelerator Mass Spectrometry Use HCIs for isobar separation Example with bare ions: Bare Ca-41: q/m=+20/41 Bare K-41: q/m=+19/41 C. Vockenhuber, Research Associate EBIS/T /26

23 Future Plans & Ideas Isotope shift measurements of transition energies in highly charged ions M M Ar M M Ar Kr Kr = = ISAC produces a wide range of exotic isotopes Visible spectrometer Test relativistic theory of isotope shifts M M = 31 ; λ = nm 84 EBIS/T /26

24 Future Plans & Ideas Isotope shift measurements in singly charged ions to investigate systematic effects on astrophysical measurements of the fine-structure constant variation. Isotope shifts ~1 ppm EBIS/T /26

25 Summary TITAN : High-precision mass measurements. TITAN EBIT is used as a charge breeder to boost the precision of mass measurements. Current EBIT max. energy & current are ~70 kev & ~500 ma. Trap on-line short-lived isotopes. Cryogen-free superconduction magnet. 9 drift tubes: short and long trap configurations Segmented central drift tube in 8 indep. electrodes. In the future, the cathode will be upgraded to 5 A. EBIT won t be limited to charge breeding X-ray / Visible / Laser spectroscopy of exotic isotopes. EBIS/T /26

26 Members / Collaborators M. Brodeur, T. Brunner, A. Bylinkii, C. Champagne, J. Dilling, P. Delheij, M. Good, A. Lapierre, C. Leung, C. Marshall, R. Ringle, V. Ryjkov, M. Smith, for the TITAN collaboration. U. of Manitoba McGill U. Muenster U. MPI-K GANIL U. of Calgary U. of Windsor Colorado School of Mines UBC Everybody s welcome Thanks! EBIS/T /26

27 Future Plans & Ideas One-proton halo Two-proton halo Binary system One-neutron halo Two-neutron halo Four-neutron halo EBIS/T /26

28 Future Plans & Ideas Model-independent measurements of nuclear charge radii of halo nuclei by laser spectroscopy in He-like 11,12 N ions ~1 µs Laser-induced de-excitation ~10 µm Decay to 1s 2 1 S 14.7 ns Nuclear size effect: λ/λ~5x10-7 (14 vs 12) Distinguish diff. models: λ/λ~5x10-8 Linewidth: λ/λ~2x10-7 ; λ/λ~2x10-8 with high stat. f/f~8x10-9 (200-kHz tunable CO 2 laser bandwidth) λ/λ~ 2x10-8 Dopplerwidth 90 deg.; ~10 π mm mrad transverse emittance) Long shot!!!! Myers et al., PRL, (1996) EBIS/T /26