a stark decelerator for ammonia molecules ruth buning master research project lcvu amsterdam...

A Stark decelerator A Stark decelerator for ammonia for ammonia

moleculesmolecules

Ruth BuningRuth BuningMaster research projectMaster research project

LCVU AmsterdamLCVU AmsterdamSupervisor: Rick BethlemSupervisor: Rick Bethlem

MotivationMotivation

High resolution spectroscopyHigh resolution spectroscopy Variation of constants of natureVariation of constants of nature

CollisionsCollisions

MotivationMotivation

High resolution spectroscopyHigh resolution spectroscopy

Proton-electron mass ratio =me/mp

Ammonia,

NH3

MotivationMotivationVariation of Variation of =m=mee/m/mpp

On a cosmological timescale:On a cosmological timescale:

Compare HCompare H22 spectra of different spectra of different epochs:epochs:

QSO12 Gyr ago

Labtoday

Reinhold et al, PRL 96 (2006) 151101Ubachs et al, JMS 241 (2007) 155

In the lab:In the lab:

Compare ‘clocks’Compare ‘clocks’

Sensitivity to mSensitivity to mee/m/mpp

Comparison timeComparison time AccuracyAccuracy

Ammonia NH3

CeasiumCs

MotivationMotivationVariation of Variation of =m=mee/m/mpp

High resolution High resolution spectroscopyspectroscopy

Transit-time broadeningTransit-time broadening

Even higher resolution..Even higher resolution.. Fountain, clockFountain, clock

The Stark deceleratorThe Stark decelerator

How can we produce and detect as How can we produce and detect as much slow NHmuch slow NH33 as possible? as possible?

Dipole in E fieldDipole in E field

cosF p E

effW p EStark shift:

Stark shift in ammoniaStark shift in ammonia

Low-field seekers

High-field seekers

Dipole in E field (2)Dipole in E field (2)

DecelerationDeceleration

SetupSetup

Molecular beamMolecular beam

Pulsed beamPulsed beam Supersonic expansionSupersonic expansion Few % NHFew % NH33 in Xe in Xe Valve coolingValve cooling

The deceleratorThe decelerator

Time to switchTime to switch

Time to switchTime to switch

DetectionDetection

2+1 REMPI2+1 REMPI

ResonanceResonance

EnhancedEnhanced

MultiMulti

PhotonPhoton

IonizationIonization

MeasurementsMeasurements

Wavelength scanWavelength scan

TOF (time of flight) scanTOF (time of flight) scan

SpectrumSpectrum Low field seeking state

Decelerator off

Decelerator at 3 kV

TOF profileTOF profile

TOF profileTOF profile

TOF profileTOF profile

OptimizationOptimization

Beam qualityBeam quality Ammonia percentageAmmonia percentage Temperature valveTemperature valve Stagnation pressureStagnation pressure

Detection efficiencyDetection efficiency Laser power and focusLaser power and focus

OptimizationOptimization

Beam qualityBeam quality Ammonia percentageAmmonia percentage 5 %5 % Temperature valveTemperature valve -50 -50 ooCC Stagnation pressureStagnation pressure 0.5 bar0.5 bar

Detection efficiencyDetection efficiency Laser power and focusLaser power and focus ~15 mJ/p~15 mJ/p

Slow ammonia (1)Slow ammonia (1)

100 m/s

Slow ammonia (2)Slow ammonia (2)

ConclusionsConclusions Stark decelerator operationalStark decelerator operational Down to 25 m/sDown to 25 m/s AdaptationsAdaptations

Differential pumpingDifferential pumping FocusingFocusing

-> Molecular fountain-> Molecular fountain

FountainFountain

OutlineOutline

Why decelerate?Why decelerate? Why ammonia?Why ammonia?

Neutral polar molecules in E fieldsNeutral polar molecules in E fields

The machineThe machine

Slow ammoniaSlow ammonia

OptimizationOptimization

Beam qualityBeam quality Ammonia percentageAmmonia percentage 5 %5 % TemperatureTemperature Backing pressureBacking pressure Valve openingValve opening

Detection efficiencyDetection efficiency Laser powerLaser power Laser focusLaser focus

OptimizationOptimization

Beam qualityBeam quality Ammonia percentageAmmonia percentage 5 %5 % TemperatureTemperature -50 -50 ooCC Backing pressureBacking pressure Valve openingValve opening

Detection efficiencyDetection efficiency Laser powerLaser power Laser focusLaser focus

OptimizationOptimization

Beam qualityBeam quality Ammonia percentageAmmonia percentage 5 %5 % TemperatureTemperature -50 -50 ooCC Backing pressureBacking pressure Valve openingValve opening

Detection efficiencyDetection efficiency Laser powerLaser power Laser focusLaser focus

Backing pressureBacking pressure

ClustersClusters

OptimizationOptimization

Beam qualityBeam quality Ammonia percentageAmmonia percentage 5 %5 % TemperatureTemperature -50 -50 ooCC Backing pressureBacking pressure 0.5 bar0.5 bar Valve openingValve opening

Detection efficiencyDetection efficiency Laser powerLaser power Laser focusLaser focus

Valve openingValve opening

OptimizationOptimization

Beam qualityBeam quality Ammonia percentageAmmonia percentage 5 %5 % TemperatureTemperature -50 -50 ooCC Backing pressureBacking pressure 0.5 bar0.5 bar Valve openingValve opening

Detection efficiencyDetection efficiency Laser powerLaser power Laser focusLaser focus

Laser powerLaser power

Slow ammonia (2)Slow ammonia (2)

Slow ammonia (2)Slow ammonia (2)

Slow ammonia (2)Slow ammonia (2)

Slow ammonia (3)Slow ammonia (3)

Slow ammonia (3)Slow ammonia (3)

Slow ammonia (3)Slow ammonia (3)

Slow ammonia (3)Slow ammonia (3)