Commissioning of the radio frequency quadropole buncher cooler
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TRI µP – T rapped R adioactive I sotopes: µ -laboratories for fundamental P hysics. U Dammalapati, S. De, P G Dendooven, O Dermois L. Huisman, K Jungmann, A.J. Mol, G Onderwater, A Rogachevskiy, M Sohani, E Traykov, L Willmann and H W Wilschut.

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Commissioning of the radio frequency quadropole buncher cooler

TRIµP – Trapped Radioactive Isotopes: µ-laboratories for fundamental Physics

U Dammalapati, S. De, P G Dendooven, O Dermois L. Huisman, K Jungmann, A.J. Mol, G Onderwater, A Rogachevskiy, M Sohani, E Traykov, L Willmann and H W Wilschut

Commissioning of theRadio Frequency Quadropole Buncher Cooler

Lorenz Willmann

SMI-06, Groningen 27/28.3.2006


Tri m p project and facility
TRImP project and facility

TrappedRadioactiveIsotopes: micro-laboratoriesfor FundamentalPhysics

AGOR

cyclotron

Magnetic separator

D

Q

Q

D

Production

Target

Wedge

Q

MeV

Q

Q

Nuclear Physics

D

Q

Magnetic

Separator

D

Production

target

Ion

Catcher

Q

keV

Q

Atomic Physics

eV

RFQ

Cooler

Thermo Ionizer:

Talk by M. Sohani

Thermo-ioniser

meV

AGOR cyclotron

MOT

RFQ cooler/buncher

MOT

Beyond the Standard Model

TeV Physics

Particle Physics

neV

MOT

Low energy beam line


Commissioning of the radio frequency quadropole buncher cooler

  •  details of b-decays

    • Na, Ne isotopes

Experimental Program of TRImP group

Investigating discrete symmetry violations C, P, and T.

  • Dominance of Matterover Antimatter

CP - Violation

Time Reversal Symmetry

Parity Violation

 permanent electric dipole moments

Ra isotopes



The role of atom trapping
The role of atom trapping

  • long storage times

  • isotope (isomer) selective

  • spin manipulation

  • point source, no substrate

  • recoil ion momentum spectrometry

  • state preparation (for APNC,edm…)

  • “low” EM fields (otherwise ion traps)

  • Ideal environment

  • for precision experiments


Commissioning of the radio frequency quadropole buncher cooler

TRImP project and facility

TrappedRadioactiveIsotopes: micro-laboratoriesfor FundamentalPhysics

AGOR

cyclotron

Magnetic separator

D

Q

Q

D

Production

Target

Wedge

Q

MeV

Q

Q

Nuclear Physics

D

Q

Magnetic

Separator

D

Production

target

Ion

Catcher

Q

keV

Q

Atomic Physics

eV

RFQ

Cooler

meV

AGOR cyclotron

MOT

MOT

Beyond the Standard Model

TeV Physics

Particle Physics

neV

MOT

Low energy beam line


Tri m p rfq cooler buncher concept

2 x 330 mm

  • DC drag resistor chain

  • Standard vacuum parts (NW160)

  • UHV compatible design and materials

  • RF: 05-1.5MHz, 200Vpp,

TRImP RFQ cooler/buncher concept

U+VcosWt

-(U+VcosWt)

Buffer gas pressure (He):

Trap position

~10-1 mbar

~10-3 mbar

10eV

RFQ ion cooler

thermal

RFQ ion buncher

Switching on end electrodes


Rfq system drift tube
RFQ System/Drift Tube

Pulsed

extraction

tube

RFQ

buncher

Ion Pulses to

experiments

RFQ

cooler

pHe~ 10-6 mbar

Beam

from TI

pHe~ 10-3 mbar

pHe~ 10-1 mbar

Background pressure 10-8 mbar


Commissioning of the radio frequency quadropole buncher cooler

  • RFQ Rods:

  • Many UHV resistors

  • segments individually coupled

  • flexible axial potential design

  • few RF connections

  • Drift tube Accelerator:

  • ideal for pulsed setup

  • no HV platform


Commissioning of the radio frequency quadropole buncher cooler

Transmission efficiencies with He buffer gas

pA

pA

 (RFQ1)= I(EL3+10)/I(load) =

=50÷70%

 (RFQ2)= I(10)/I(EL3+10) =

=50÷80%

 (RFQ1+RFQ2)= I(10)/I(load) =

=25÷40%

I(load) = max.(I(EL2)+I(EL3)+I(10))

Both I(EL2) and I(10) increase with

increase of difference between U(3,5) and U(4)

(DU  14 V)

I(EL2) RF off

I(EL3)

Acceleration-deceleration

essential for transmission

between RFQ1 and RFQ2!

I(EL2)

I(10)

23Na+ ions

@ 10 eV, 15 eV

U(acc) = 10 V, 15 V

p(1): from 10-6 to 10-1 mbar

U(4): from 0 V to +36 V

(EL2), (EL3) and (10)

connected to pA-meter

(11) at same potential as (1)

U(acc) = 10 V

p(1) = 3.5*10-2 mbar

U(4): from 0 V to +36 V

EL3 and (10) connected to

pA-meter

(11) at same potential as (1)

pA

EL1

EL2

EL3

MCP

Ion

Source

(8)

(11)

(1)

p(1)

p(2)

(3)

(5)

Low Energy

beam line

Drift tube

(4)

(7)

(9)

(10)


Commissioning of the radio frequency quadropole buncher cooler

Simple Diagostic Tool: MCP with phosphor screen

2

2

-2

2

-2

2

-2

-2

119 V pp

120 V pp

  • Positional resolution, transverse emittance

  • Counting mode for low rate


Commissioning of the radio frequency quadropole buncher cooler

Filling of trap with different loading rates

Space charge limited

Heater Current

On ion source


Commissioning of the radio frequency quadropole buncher cooler

Storage times of RFQ buncher

Storage time limitations:

- Space charge effect

- Impurities in the gas

3.5.10-4 mbar He gas (~10-8 mbar background)

without baking of system and standard gas purity (Helium 5.0)


Commissioning of the radio frequency quadropole buncher cooler

Direct detection of ion pulse on readout electrode

Signal [V]

Time [ms]

  • Charge integrating amplifier

  • rise time 40 nsec

  • integration time 20 msec

  • sensitivity 1 mV/1500 ions

  • noise 3 mV

Storage time

100 msec

Data averaged over 128 extraction cycles

10 msec

1 msec

Extraction pulse

Drift tube pulse


Tri m p rfq cooler buncher system
TRImP RFQ cooler buncher system

  • Storage time several seconds achieved -> purity of buffer gasexpected 21Na production rate fills trap in 1s

  • Drift tube accelerator -> no high voltage platform

  • Good transmission > 70% of RFQ

  • Vacuum conditions good to couple to Magneto-optical Trap

    More results in the forthcoming thesis of Emil Traykov


Commissioning of the radio frequency quadropole buncher cooler

Coupling of RFQ and Low Energy beamline to MOT

Trapping while operating RFQ achieved last Friday

-> good differential pumping