Cryogenic ion catchers using superfluid helium and noble gases

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Cryogenic ion catchers using superfluid helium
and noble gases

• Sivaji Purushothaman
• KVI, University of Groningen
• The Netherlands

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Content

• Introduction
• Superfluid Helium
• Cryogenic gas catchers
• Off-line
• On-line
• Summary
• Future plans

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High density at low temperature
??????????????e??t Impurities get frozen out !!!
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Cold RIBs from superfluid helium concept
N. Takahashi et al.

• extraction across the surface into the vapour
  region

trivial
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?-decay recoil ion source
ranges in LHe recoil 0.5 ?m ?? 500 ?m
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How to extract snowballs at low temperature ?
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Electric-field assisted extraction
up to 1200 V/cm no enhanced extraction
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Evaporation by second sound
Second sound - heat wave without a pressure wave
SF helium cell configuration
heater design
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Release of ions by evaporation
219Rn released from the surface and transported
to the foil
1.05K
219Rn trapped at the surface
7.2(6)  extraction efficiency
if thermal motion only 0.04 
few  overall efficiency
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A cryogenic gas catcher

• impurities in noble gas ion catchers
• limit the performance
• neutralization of ions (near or at thermal
  velocities)
• formation of molecules/adducts

• remove impurities
• 1) ultra-clean system
• UHV compatible
• bakeable
• helium purification lt ppb
• ? not trivial (esp. large cells)
• 2) freezing the impurities

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Efficiencies at low temperature
P. Dendooven et al., NIM A 558 (2006) 580
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Online experimental setup (JYFL)
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On-line measurements
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On-line measurements
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On-line measurements
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Summary of the data
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Recombination loss - f
M.Huyse et al., NIMB, 187, 2002, Pages 535-547

Ramanan, G. Freeman, Gordon R., Journal of
Chemical Physics, 93, 1990, 3120
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Efficiency vs. Recombination loss
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Off-line Measurements for different pressures and
temperatures
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Summary

• Evidence for 2nd sound assisted extraction from
  superfluid helium
• Cryogenic gas catchers work
• High beam intensities require high electric fields

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Near future plans

• Off-line test of second sound assisted extraction
  from superfluid helium
• On-line test of cryogenic gas catcher using
  radioactive ion beams
• Transport of ions to high vacuum, room
  temperature region

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Collaborators

• Juha Äysto (JYFL, Jyväskylä)
• Peter Dendooven (KVI, Groningen)
• Kurt Gloos (University of Turku)
• Takahashi Noriaki (Osaka Gakuin University)
• Heikki Penttilä (JYFL, Jyväskylä)
• Kari Peräjävi (JYFL, Jyväskylä)
• Sami Rinta-Antila (JYFL, Jyväskylä)
• Perttu Ronkanen(JYFL, Jyväskylä)
• Antti Saastamoinen (JYFL, Jyväskylä)
• Tetsu Sonoda (JYFL, Jyväskylä)