Optimal beam sources for Stark decelerators in collision experiments: a tutorial review.

Zhi Gao,Sjoerd N Vogels,Sebastiaan YT van de Meerakker

doi:10.1140/epjti/s40485-015-0021-y

Zhi Gao, Sjoerd N Vogels

Open Access

https://doi.org/10.1140/epjti/s40485-015-0021-y

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Abstract

With the Stark deceleration technique, packets of molecules with a tunable velocity, a narrow velocity spread, and a high state purity can be produced. These tamed molecular beams find applications in high resolution spectroscopy, cold molecule trapping, and controlled scattering experiments. The quality and purity of the packets of molecules emerging from the decelerator critically depend on the specifications of the decelerator, but also on the characteristics of the molecular beam pulse with which the decelerator is loaded. We consider three frequently used molecular beam sources, and discuss their suitability for molecular beam deceleration experiments, in particular with the application in crossed beam scattering in mind. The performance of two valves in particular, the Nijmegen Pulsed Valve and the Jordan Valve, is illustrated by decelerating ND 3 molecules in a 2.6 meter-long Stark decelerator. We describe a protocol to characterize the valve, and to optimally load the pulse of molecules into the decelerator. We characterize the valves regarding opening time duration, optimal valve-to-skimmer distance, mean velocity, velocity spread, state purity, and relative intensity.

Highlights

Over the last decades, there has been tremendous progress in the ability to manipulate molecular beams
We report on measurements of beams of ND3 that pass through a 2.6 meter-long Stark decelerator, from which we quantify the opening characteristics of the Jordan Valve (JV) and Nijmegen Pulsed Valve (NPV)
Time-of-flight profiles using a Jordan valve and Nijmegen Pulsed Valve We have systematically studied the performance of a JV and NPV as a source for Stark decelerators by recording series of TOFs following the beam loading protocol described above

Summary

Introduction

There has been tremendous progress in the ability to manipulate molecular beams. A packet of molecules is selected from the molecular beam pulse, is decelerated, and arrives in the interaction region at later times.

Results

Conclusion