Marina QuinteroPrez Paul Jansen Thomas E Wall Wim

Marina Quintero-Pérez Paul Jansen Thomas E. Wall Wim Ubachs Hendrick L. Bethlem

Motivation Why cold molecules? COLD = low velocities Long coherence times High precision measurements

Motivation Why a molecular fountain? Measure the inversion frequency of ammonia Need: Molecules travelling at 3 m/s Sensitive to variation of the proton-to-electron mass ratio v = 3 m/s L= 30 cm ∆t = 0. 5 sec ∆f = 1 Hz

Experimental set-up PROBLEM: v~100 m/s v~300 m/s ion detector Stark decelerator Poor efficiency at low velocities - Couplings - Overfocusing

Experimental set-up SOLUTION: RING DECELERATOR v~100 m/s 336 rings separated by 1. 5 mm Voltage applied by 8 HV amplifiers -5 ≤ V ≤ 5 k. V v~300 m/s 0 ≤ f ≤ 15 k. Hz (vmax~150 m/s)

Ring decelerator: operating principle Variation Fixed time with time Vn = V 0 sin(-2πft+2πn/8)

Comparing NH 3 and ND 3 STARK SHIFT Inversion splitting much smaller in ND 3 than NH 3 ND 3 Stark shift - greater - very linear

Guiding NH 3 ND 3

NH 3 ND 3 Guiding Decelerating

NH 3 Guiding Decelerating Trapping Quintero-Pérez et al. , PRL 110, 133003 (2013) ND 3

NH 3 Guiding Decelerating Trapping for 50 ms Quintero-Pérez et al. , PRL 110, 133003 (2013) ND 3

Reducing the trap depth tramp = 2 ms tramp = 10 µs tramp ND 3

Modulating the trap NH 3 ND 3

Conclusions and Outlook § First trapping on a ring decelerator (avoiding losses at low velocity) § Great control over the trapped molecules - Measurement of the characteristic frequencies - Cooling - Phase space High enough density of molecules at 3 m/s? manipulation A Molecular Fountain!

Questions?

Trap position Inside a ring Between two rings

Trap position

Transverse oscillations

Oscillations

ND 3 and NH 3 100 m. K 14 m. K

Effect of Tramp on signal A measure of adiabaticity 5 k. V – 2 k. V – 5 k. V

Electric field Inside a ring Between two rings

Phase* jumps vz az= 0 az< 0 * Phase = Position of trap centre az> 0

Phase jumps 90 – 90 m/s 70 – 70 m/s |a| = 15, 000 m/s 2; Ttrap = 50 ms