1. Simulations and tests for PIPERADE P. Ascher, K. Blaum, M. Heck, S. Naimi Piperade Meeting, 27 th -28 th May 2013, Bordeaux

2. SImultaneous Magnetron and resonant COnversion - Dipolar excitation at the magnetron frequency - - Quadrupolar excitation at ( + +  - ) for the conversion of the radial modes M. Rosenbusch et al, Int. J. M. Spec., 325-327, 51-57 (2012) M. Kretzchmar, Int. J. M. Spec., 325-327, 30-44 (2012) One SIMCO conversion Allows to center the ions selectively without buffer gas -> prevents charge-exchange reactions and damping of the motion that decreases mass resolving power R+R+ R-R- SIMCO excitation: Introduction

3. SIMCO excitation Advantages of SIMCO  No Buffer gas  Mass independent (like BG)  Same selectivity as a quadrupole excitation (same resolution for a given time) BUT for BG cooling a magnetron exc and a cooling time afterwards are needed! → SIMCO is faster (for a given time, SIMCO has a higher resolving power)  Contaminants are brought further compared to the ions of interest, the contaminants can even leave the trap (depends on the magnetron exc parameters…)

4. SIMCO excitation vs BG Cooling SIMCO Exc during 60ms Mag Exc during 4 ms + Quad Exc during 60ms + Cooling time of 100 ms P=1e-4 mbar Time (ms) R+, R- (mm)R (mm) R+, R- (mm)R (mm) Time (ms) 2 ions species: 136 Te, 136 Sb

5. SIMCO excitation vs BG Cooling SIMCO Exc during 60ms Mag Exc during 4 ms + Quad Exc during 60ms + Cooling time of 100 ms P=1e-4 mbar Time (ms) R+, R- (mm) R (mm)

6. SIMCO excitation What is tricky with SIMCO…  One conversion is needed (exactly), time excitation is crucial!  Ions probe radial anharmonicities of the E/B fields during the exc (like BG)  No Buffer gas  Initial conditions crucial! (in particular radial dispersion) this is not a cooling method, the conditions at the end will not be better than before

7. During the excitation, the ions probe radial anharmonicities of the trap (B field inhomogeneities) B 2 =5.6 (corresponding to an homogeneity of 10 ppm over 5 mm) B 2 =0.3 (corresponding to an homogeneity of 5ppm over 5 mm) -> WITCH Magnet (Oxford) Time (ms) R (mm)

8. B 2 =5.6 (corresponding to an homogeneity of 10 ppm over 5 mm) R (mm) Time (ms)

9. SIMCO excitation What is tricky with SIMCO…  One conversion is needed (exactly), time excitation is crucial!  Ions probe radial anharmonicities of the E/B fields during the exc (like BG)  No Buffer gas  Initial conditions crucial! (in particular radial dispersion) this is not a cooling method, the conditions at the end will not be better than before

10. Inittial conditions are crucial! Radial dispersion But if they are all off-centered this is ok because we can change the phase… R (mm) R 0 = 1 mmR 0 = 2 mm R 0 = 3 mm Time (ms)

11. SIMCO excitation: Simulations Initial magnetron motion? R+(t), R-(t)  mag.motion -  mag.exc  = -  /2  = 0 SIMCO excitation during 15 ms R+(t), R-(t)

12. Initial conditions Z direction B 2 =0.3 (corresponding to 10 ppm over 3 cm)B 2 =3 (correspondingto 100 ppm over 3 cm)  z= 30 mm R (mm) Time (ms)

13. Increasing the number of ions… the main problem is the shielding effect Initial conditions (  x,  y,  z ) = (0.5 mm, 0.5 mm, 15 mm) 512 ions Scaling factor of 2: ~ 1000 contaminants 2 ions of interest Initial conditions (  x,  y,  z ) = (0.5 mm, 0.5 mm, 2 mm) R (mm) Time (ms) R+, R- (mm)

14. Tests at MPIK Quadrupolar excitation SIMCO excitation Time (ms) R+, R- (mm) Time (ms)

15. Tests with MCP detection An aperture was installed after the trap in order to see a count-rate resonance, but it was not possible to shoot through the aperture -> Initial magnetron motion too high…. A phosphore screen detector was installed -> Beam not aligned What is crucial to improve: the tilted magnetic field and the injection in the trap:  Magnetic field: An engineer from BRUKER will come in the next weeks to shim again the magnet  Injection: the RFQ is designed and built, still electronics has to be developed… SIMION simulations of the RFQ in progress Tests @ MPIK

16. SIMCO tests in the preparation trap: - We need to use the RFQ to have good conditions - No vacuum possible if we use the RFQ FIrst tests of SIMCO will be done in the measurement trap: No aperture after the second trap but position-sensitive detector (even better!) First of all is to look at the beam spot position depending on the excitation time and at the same time the TOF as a function of the exc time The method will be investigated up to 100 ions (very high number of ions for SHIPTRAP) Tests @ SHIPTRAP/GSI