On-line tests RFQ coolerISCOOL

A quick summary

P. Delahaye, H. Frånberg,I. Podadera

ISCOOL, COLLAPS, ISOLDE collaboration

Where at ISOLDE

Installation in pictures

Principle

RFV

Three elements:RF quadrupolar fieldRadial confinement

DC potentialsExtracting ion in bunches or in continuos mode

Buffer gas Ion motion cooling

Emittance measurements• Without cooling • With cooling

~35·mm·mrad 95% emittance

~2.2·mm·mrad 95% emittance

Transmissions• Potentials along the axis

• Transmissions in DC – 23Na: 50%– 39K: >75%– 85Rb: >75%

Better than the off-line tests!Smaller emittances from ISOLDE surface ion sources than from the ion source used during off-line tests.

80eV5-2V/cm

~1E-2 mbar 4He10-2mbar l/s

EXTRACTIONINJECTION

50V (30V enough)

TRAPPING

Cooling time• TOF < 1ms from the entrance to the exit of

the RFQ

• 1 passage is enough to get a cold beam – as measured off-line, and other labs as

predicted by simulations for other systems

-200 0 200 400 600 800 1000 1200 1400 1600 1800-1

0

1

2

3

4

4.0x10-4

6.0x10-4

8.0x10-4

1.0x10-3

1.2x10-3

1.4x10-3

1.6x10-3

Bea

m g

ate

Time [s] M

CP

Bunching mode

30keV

80eV5-2V/cm

~1E-2 mbar 4He10-2mbar l/s

EXTRACTIONINJECTION

50V (30V enough)

TRAPPING

Space charge limits

• Up to 108/s!! As measured with FC (data under analysis with MCP)

0.00E+000 1.00E+009 2.00E+009 3.00E+009 4.00E+009 5.00E+009

0.00E+000

2.00E+007

4.00E+007

6.00E+007

8.00E+007

1.00E+008

1.20E+008

1.40E+008

Ext

ract

ed

ion

s

Injected ions

39K

0.00E+000 4.00E+008 8.00E+008 1.20E+009-2.00E+007

0.00E+000

2.00E+007

4.00E+007

6.00E+007

8.00E+007

1.00E+008

1.20E+008

1.40E+008

1.60E+008

Ext

ract

ed io

ns

Injected ions

85Rb

Bunch width• Depends on the space charge and cooling

time

Collection / cooling time

-40 -20 0 20 40 60 80 100 120 140

-8x10-3

-7x10-3

-6x10-3

-5x10-3

-4x10-3

-3x10-3

-2x10-3

-1x10-3

0

1x10-3

2x10-3

MC

P s

igna

l

Time [s]

10 ms 100 ms 1000 ms

Preliminary results

• Data from 26Na needs to be analyzed

• Losses due to trapping time (analysis in progress)

• Chemistry, noble gases, reactive elements

• More data needed for more masses (light ions)– CaO target + plasma ion source should

provide some answers

-7 -6 -5 -4 -3 -2 -1

0

20

40

60

80

100

120

140

160

180

200

Gat

ed c

ount

s

Tuning voltage

-7 -6 -5 -4 -3 -2 -1

490000

492000

494000

496000

498000

500000

502000

Tot

al c

ount

s

Tuning volts

ISCOOL TEST46K Beam 1E5 ions/s after the cooler. Collection time 20 minutes, with 300ms bunching and a 12us gate and 2mW of laser power.

Singles (continuous counting)Bunched:12us gated spectra

Background suppression factor~1E4

Thanks to:• AB-OP-PSB-iso team:

Pascal, Erwin, Magnus, Emiliano and Tim.

• AB/ATB• AB/CO• AB/PO• AB/VAC

• SC/RP• ISOLDE collaboration• COLLAPS collaboration• ISCOOL collaboration