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