Simulations and testing of JYFLTRAP extraction

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Simulations and testing of JYFLTRAP extraction
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About JYFLTRAP

• Two Penning traps
• Inside same magnet (7 T)
• In High voltage of lt 40 kV
• First trap isobaric separation
• Filled with gas
• Operated succesfully since 2002
• Second trap precision trap
• First resonance on 8/2003

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Injection Extraction

• Injection from RFQ
• In 15 ms bunches
• Beamline at -900 V
• Extraction
• HV to ground potential ( 6 kV to 0)
• From first trap to
• Precision trap
• Tape station, MCP1 or MCP2, FC1 or FC2
• From precision trap to first MCP

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Potentials

• 6 kV high voltage
• Purification trap depth 100 V
• Precision trap depth 30 V
• Extraction beam line 3 V below 1st trap until
  plug electrode
• Beam diverges rapidly after plug electrode

20 cm
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Simulations

• Simulating extraction from precision trap
• Exaggerating simulation conditions
• Huge radial energy
• Ion position far away from center line
• Introducing huge magn. field disalignment
• Extraction from purification trap
• All passing diaphragm
• Using precision trap as electric dipole
• disalignment tests

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Testing Conditions

• IGISOL upgrade until end of 2003
• No experiments until 2004
• Using off-line test ion source (Xenon)
• Mounted before RFQ (temporary)
• Low high voltage of 6 kV
• Improved extraction tuning
• Time-of-flight measurements

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Testing

• Time-of-flight spectrums
• Checking countrate on each point
• Improved extraction efficiency
• tuning, when necessary

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Testing Misalignment

• from simulations
• Putting other side of ring electrode 50 V lower
  corrects disalignment of 0.5 mm
• tested with isobarically pure beam
• up-down 50 V no big effect
• left-right beam lost easily
• beam is not cylindrical
• extraction xy-steerers indicate same

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Time-of-Flight Resonances

• Excitation time 400 ms
• Amplitude 28 mV
• No significant problem with buffer gas leaking
  from purification trap
• Magnetron phase locking effect 35 ms
• With Xe-isotopes, time-of-flight effect is
  roughly 25 (60 ms).

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Time-of-Flight Resonance of 128Xe
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Conclusions
Future

• Exaggerated simulation conditions
• Extraction ok with simulations
• Buffer gas is no problem in precision trap
• 128Xe (1.91 of all Xe) measured
• Bad sometimes countrate drops. Charging?

• Off-line test in HV
• Experiments start 2004
• masses
• spectroscopy with isobarically pure beam