ISOLDE WS 2007

Results with ISCOOL a new Radio Frequency

Quadrupole Cooler and Buncher at ISOLDE

P. Delahaye, H. Frånberg,

AB-OP-PSB, ISCOOL, COLLAPS, ISOLDE collaboration

ISOLDE WS 2007

ISCOOL

Where at ISOLDE

ISOLDE WS 2007

Installation in pictures

ISOLDE WS 2007

INSTALLATIONImplementation of the RFQ into the ISOLDE

vacuum system.Construction of HV platform and HV cage of

the RFQ. Standard controls in the working sets: QP

arrays for the RFQ and for the beam tuning after the cooler.– RF and gas still on LabVIEW.

ISOLDE WS 2007

OPERATION OF ISCOOL

• Set-up by the ISOLDE operators.

• Improved transmission past the switchyard Improved (faster and easier) set-up for the beam

to the experiments

ISOLDE WS 2007

Principle

RFV

Three elements:RF quadrupolar fieldRadial confinement

DC potentialsExtracting ion in bunches or in continuous mode

Buffer gas Ion motion cooling

ISOLDE WS 2007

Transmissions

• Potentials along the axis

Transmission dependence on the emittance of the ISOLDE ion sources.ISOLDE on-line surface ion sources has smaller emittance than ISOLDE FEBIAD ion sources (<25 π·mm mrad). The off-line tests were performed with an ion source with ε = 35π mm mrad

80eV

5-2V/cm

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

EXTRACTIONINJECTION

50V (30V enough)

TRAPPING

0 20 40 60 80 100 120 1400

20

40

60

80

100

Mass

Tra

nsm

issi

on

on-line surface ionsourceon-line plasma ionsourceoff-line surface ionsource

ISOLDE WS 2007

Bunching mode

30-60 keV

80eV5-2V/cm

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

50V (30V enough)

TRAPPING

ISOLDE WS 2007

Cooling time• TOF < 1ms from the

entrance to the exit of the RFQ– No losses for short

lived ions.

• 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]

MC

P

ISOLDE WS 2007

Emittance measurements (off-line)~35·mm·mrad 95% emittance

~2.2·mm·mrad 95% emittance

• 10 x decrease of the beam emittance– The worst case scenario

at ISOLDE is the FEBIAD ion source with >25 p·mm·mrad emmittance.

• Injection efficiency into the cooler is depending on the beam emittance from the ISOLDE target and ion source unit.

ISOLDE WS 2007

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

ion

s

Injected ions

Space charge limits

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

0 1x109 2x109 3x109 4x109 5x109

0.0

2.0x107

4.0x107

6.0x107

8.0x107

1.0x108

1.2x108

1.4x108

Ext

ract

ed io

ns

Injected ions

39K, Collection time=10 ms–1 secExtraction time 150 us

85Rb

0.0 5.0x107 1.0x108 1.5x108 2.0x108 2.5x108

0.0

2.0x106

4.0x106

6.0x106

8.0x106

1.0x107

1.2x107

1.4x107

Ext

ract

ed io

ns

Injected ions

23Na

ISOLDE WS 2007

Bunch width

Depends on the space charge and 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

Collection time=cooling time

ISOLDE WS 2007

Yield measurements

• 26Na T1/2=1.07 s

• 48K T1/2=6.8 s

• Yields in continuous mode: – 26Na :1.2e6 at/uC– 48K: 2.2e4 at/uC

• Yields in bunched mode – analysis under progress

ISOLDE WS 2007

HOT SPOTS

0.5 µSv/h15 µSv/h

10 µSv/h

3 µSv/h

10 µSv/h

15 µSv/h

5 µSv/h5 µSv/h

0.5 µSv/h

Beam direction

ISOLDE WS 2007

Results

• High transmission efficiencies

• Easy beam tuning to experiments

• Yield measurements continuous vs. bunched mode

• Losses due to trapping time (analysis in progress

• First measurements with radioactive isotopes performed together with COLLAPS (see next talk)

ISOLDE WS 2007

ISOLDE HRS + Cooled beams

HRSIS

COO

L

ISOLDE WS 2007

OutlookUp to October 2007:

From Nov. 2007:

Next step:

Upgrade of HRS Mag 90:

EURISOL HIE Isolde:

ISOLDE WS 2007

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

ISOLDE WS 2007

ISOLDE WS 2007

ISCOOL tests with COLLAPS46K Beam 1E5 ions/s after the cooler. Collection time 20 minutes, with 300ms bunching and a 12us

gate and 2mW of laser power.

-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

To

tal c

oun

ts

Tuning volts

Singles (continuous counting)Bunched:12us gated spectra

Background suppression factor~1E4