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Simulations and tests for PIPERADE

Simulations and tests for PIPERADE. P. Ascher, K. Blaum, M. Heck, S. Naimi. Piperade Meeting, 27 th -28 th May 2013, Bordeaux. SIMCO excitation: Introduction. M. Rosenbusch et al, Int. J. M. Spec., 325-327, 51-57 (2012) M. Kretzchmar, Int. J. M. Spec., 325-327, 30-44 (2012).

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Simulations and tests for PIPERADE

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

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

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

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

  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) B2=5.6 (corresponding to an homogeneity of 10 ppm over 5 mm) R (mm) R (mm) Time (ms) Time (ms) B2=0.3 (corresponding to an homogeneity of 5ppm over 5 mm) -> WITCH Magnet (Oxford) R (mm) R (mm) Time (ms) Time (ms)

  8. B2=5.6 (corresponding to an homogeneity of 10 ppm over 5 mm) R (mm) R (mm) Time (ms) 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 R0 = 1 mm R0 = 2 mm R (mm) R (mm) Time (ms) Time (ms) But if they are all off-centered this is ok because we can change the phase… R0 = 3 mm R (mm) Time (ms)

  11. SIMCO excitation: Simulations SIMCO excitation during 15 ms R+(t), R-(t) Initial magnetronmotion? R+(t), R-(t) z = -p/2 R+(t), R-(t) z = 0 z = fmag.motion - fmag.exc

  12. Initial conditions Z direction B2=0.3 (corresponding to 10 ppm over 3 cm) B2=3 (correspondingto 100 ppm over 3 cm) Dz= 30 mm R (mm) R (mm) Time (ms) Time (ms)

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

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

  15. Tests @ MPIK • 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

  16. Tests @ SHIPTRAP/GSI 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)

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