The new operation modes of JYFLTRAP. tio. M ore

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1 The new operation modes of JYFLTRAP M M ore Fa ore be st re am er s! olu... tio n.., V. V. Elomaa, U. Hager, J. Hakala, A. Jokinen, S. Rahaman, J. Rissanen, C. Weber, J. Äystö and the IGISOL group JYFL

2 So far in Saariselkä Already covered: IGISOL, JYFLTRAP Penning trap principle gas filled trap for purification vacuum trap for high resolution work Ramsey excitation for time of flight measurements Very high resolution dipolar cleaning

3 Something to add still. There seem to be a trend that people want... More beam More pure beam also isomerically Something new wanted (by B. Blank): One bunch every 25 seconds!

4 26 Case: Si half life measurement All these produced, including stables Si 2.2s Si 26m Al Mg 28 Si Target Al 6s 26 Al(gs) ~ 700 ky 25 Mg Compound nucleus 27 Al 26 Mg 27 Al(p,2n)26Si superallowed decays isobar of interest

5 26 Case: Si half life measurement Beam after IGISOL: T1/2 ~ 6 sec isobar A=26, containing 26Si, 26Al, 26Alm, 26Mg and a few pa of other crap! JYFLTRAP purification trap used for cleaning T1/2 ~ 2.2 sec Seems to be ok, pure 26Si yield of > 200 ions/s after trap Measurement principle: implant a bunch to the counting station, count decays for 10 half lives; repeat for 2 weeks Only 1 bunch every 25 s wanted!? but one bunch has only ~50 ions of 26Si! even in 2 weeks one gets low statistics..

6 Is there a problem? Accumulate for 25 seconds and clean then? Too much crap in.. Cleaning will not work. besides, 26Si will decay too.. Seems that 250 ms accumulation time is 26 maximum. 50 ions of Si / bunch.. trap gets too full 1.7x105 decays / day rather little to reach 0.1% accuracy level in reasonable amount of time

7 Solution: Multiple injection! Accumulate for ~250 ms and clean with trap Ratio 26Si/all << 1% Rejection of > 104 unwanted ions Procedure: Accumulation in RFQ (parallel to cleaning) inject to Penning trap, quadruple sideband cleaning extract ions, unwanted ions hit the 2 mm channel electrode recapture the cleaned bunch (REPEAT N<10 times)

8 bunch from RFQ

9 ~100 V

10 cooled

11 magnetron excited

12 sideband cleaned

13 sp la t! la t! sp Rejecting unwanted..

14 recapture and recool

15 a new bunch from the RFQ cleaned bunch from previous round(s) barrier to keep cleaned ions in

16 Repeat N times Always the previous bunches get re excited too.

17 As a consequence.. Overfilling of the trap is prevented by periodic cleaning Amount of wanted ions increase in every cycle Saturation due to charge exchange, transfer efficiency, overfilling... Tested with 126 Xe. Ratio Xe/all ~ 1/2

18 26 Si T1/2+branching ratio measurement 231 ms cycles, extract after every cycle High amplitudes needed for high countrates both magnetron+cyclotron too much for single injection 26 Si : 26mAl = 7 : ms cycles, extract after 8 cycles 26 Si : 26mAl = 13 : 100 A = Si (T1/2 ~ 2.2s) 26m Al 26 (T1/2 ~ 6s) Al(gs) (~stable) 26 Mg (stable)

19 Measurement conditions Yield of Si ions/bunch obtained Si decays/s in average (~ Million/day) accumulated 8 bunches restart extraction cyclotron beam RFQ trap ~2 sec observe decays, 25 sec 26 Si 26m > 3 Million decays observed. 0.1 % T1/2 precision reached. B. Blank et al., to be published. Al 26 Mg

20 From mega bunches to high resolution. Purification trap resolution worse than 10 Hz (1 MeV for A=100 ions) sometimes enough to separate isomers... ie. 26m Al 26Al(gs), separation of ~40 Hz

21 Better resolution? With gaussian modulated dipolar excitation (K. Blaum et al. Hyp. Int. 162 (2005) 1) 70 Cu with three states. 3 second cleaning, separation ~ 2 Hz But there is no always time to do it! superallowed 50Mn, 54Co have T1/2 < 300 ms contaminating isomers 10 Hz and 7 Hz away! There has to be a faster way.

22 Fast cleaning with separated oscillatory fields Dipolar + cleaning in Ramsey mode Improved resolution by 40 % compared to normal N. F. Ramsey, Rev. Mod. Phys. 62 (1990) 541

23 Cleaning recipe Consider two states. One needs to be removed. Choose the excitation parameters: duration, frequency, short fringes Do excitation Send the bunch back to the preparation trap. rejection of unwanted (acceptance r < 1 mm) recool & recenter the survived Isomerically clean sample

24 RFQ TRAP1 TRAP1 >TRAP2 RAMSEY CLEANING EXCITATION TRAP2 >TRAP1 re cooling TRAP1 >TRAP2 TRAP2 excitations & extraction & detection

25 Transfer between the traps precision trap purification trap buffer gas (He) cooling Splatting from this side trapped transfer

26 Testing: Cleaning scan ~4.5 Hz ~480 kev 115 Sn radius after ms excitation (simulation)

27 ~ 4.5 Hz No cleaning % In % Sn

28 In through

29 Sn through

30 Application to superallowed Mn, Co Isomeric states are ~7 and ~10 Hz away ms cleaning

31 Without cleaning superallowed state Isomeric state is favoured in production.

32 Conclusions Multiple injection up to ~ 10 bunches saturation charge exchange transfer efficiency half life excitation amplitude is a function of # ions good transmission moderate resolution Ramsey cleaning high resolution fast, x5 faster than conventional complete removal not so universal for spectroscopists best for cleaning only 1 state, 2 states already tricky (ie. 70Cu case) at JYFLTRAP: parallel with frequency change (200 ms) no extra time needed

33 Outlook Ramsey cleaning to be used: Superallowed 50Mn, 54Co beamtime in May 07 with J.C. Hardy, Texas A&M In general to resolve isomeric states mass measurements along rp and r process paths for post trap spectroscopy Multiple injection to be used: In (superallowed) half life measurements 42 Ti with B. Blank et al., Bordeaux, France

34 Thank you for your attention!