Spectroscopy with purified beams RFQ cooler buncher and purification trap MRP 20 000... 150 000 Cycle time down to 100 ms Total transmission ~ 10 % Maximum intensity tens of thousands/bunch Example A=112 Coming experiments: Ga, Zr
Frequency scan over cyclotron frequencies of 112 Ru and 112 Rh, ions are detected with MCP. Mass difference is about 4 MeV. Cycle time 450 ms. MRP = 72 000. Example A=112 fission products 4 MeV
Total trap cycle 450 ms 340 ms cooling 15 ms dipole excitation f =1705 Hz/160 mV 90 ms quadrupole excitation f c =960190 Hz/150 mV -gated -spectrum collected in one hour. 112 Rh and 112 Ru were produced in proton induced fission. Test results A=112
Mass resolving power A=112 fission products Simulated frequency scans over fission products with different MRP MRP = 70 000MRP = 30 000
Experiments along N=Z line Example 62 Ga (t ½ =116ms) From old IGISOL 400 ions/s (reaction 64 Zn(p,3n) 62 Ga, E p = 48MeV, I p =35 A) 2-10 ions/s purified beam with present transmission MRP 20 000 is enough to separate 62 Zn and 62 Cu from 62 Ga Simulated frequency scan
Improving the trap extraction Cut one long electrode in the end of magnet region into two to squeeze the ion trajectories at the point where magnetic field lines start to diverge. SIMION simulations for mass A=100 q=+1 ions 2.5 m 30 mm Problematic place in extraction. Ions follow magnetic field lines. Second einzel lens added to improve transmission to the spectroscopy setup. Present geometry Planned improvement Implantation point
Challenges Transmission through the trap system (5 - 20 %) Cooler transmission has been poor since last summer (only ~30%) Install Si detectors to improve diagnostics Extraction from the magnetic field; ions tend to follow field lines Divide one electrode Shorter cycles (less than 100 ms) Find limit for Ions per bunch; space charge limit
In-trap spectroscopy Trapped ions form an ideal source without any scattering or energy loss in source material. Lineshape Peak-to-background ratio Strong magnetic field of a penning trap can be used to transport charged particles (e, p, ) to the detector with high efficiency. Conversion electrons tr ~ 50% Energy and mass selection with trajectory radius r tr In average electron r tr < proton r tr Conversion electron r tr < beta r tr
Detector: Canberra RD EB10GC-500P Thickness 500 m Active area 10 mm 2 (r = 1.78mm) Dead layer 250 Å PA1201 Pre amp Resolution less than 1 keV for 59.5 keV X-ray from 241 Am source and 1.5 2 keV for electrons from 131 Ba source In-trap detector set-up Source ions trapped in the purification trap. Source to detector distance ~60cm. Simulated transport efficiency ~50% up to 300keV.
In-trap plans Near future Selecting a good test case, good yield, t½, electron energy, conversion coefficient Trap scheduling Beamtime for testing First physics proposal: neutron rich Zr decay spectroscopy Open questions How to tune the trap injection when the ejection side is blocked by the detector ? How to arrange data acquisition because detector sits on HV platform ? Later Segmented detector to avoid summing and allow coincidence detection
Outlook and conclusions Purified beams JYFLTRAP is ready to make purified beams for spectroscopy Mass resolving power is enough for most of the cases Transmission needs still improving Systematic tests of the high intensity limit together with short cycle time In-trap spectroscopy Mechanical parts are ready Data acquisition not yet designed First test hopefully during next summer IGISOL facility IGISOL upgrade is almost ready. Improved yields have been recorded with light-ion ion guide. Laser ion source project has been started to improve ion guide efficiency and also to introduce chemical selectivity.