A jet beam source of cold YbF radicals

Abstract

We have developed a pulsed supersonic beam of slow, cold YbF molecular radicals with an intensity of 1.4 × 109 YbF molecules per steradian per pulse in the X2 Σ+ (v = 0, N = 0) ground state. The translational and rotational temperatures of the beam are equal. The lowest temperature produced was 1.4 K and the slowest centre-of-mass velocity was 290 K. We show that YbF can be made either by ablating Yb metal into a fluorine-bearing carrier gas or by ablating solid precursors into a pure inert carrier gas. This source is suitable for injecting a molecule decelerator and for high-resolution laser-rf-double-resonance studies such as the measurement of the electron electric dipole moment.

Improved measurement of the shape of the electron

“…Pulses of YbF are emitted by the source [17] every 40 ms and travel through the magneticallyshielded apparatus (figure 1) at a speed of 590 m/s. The pump detector depletes and detects the F = 1 population while the probe detector measures the F = 0 population.…”

“…Ytterbium atoms laser-ablated from a target beside the valve react with the gas pulse to form YbF. The gas expands, cools, and is skimmed to form a beam with a temperature of 3 K and a centre-of-mass velocity of 590 m/s [17].…”

“…Figure 1 shows the interferometer apparatus [16]. Pulses of YbF molecules are emitted by the source [17]. The experiment uses those molecules in the F = 0 and F = 1 hyperfine levels of the ground state.…”

The Buffer Gas Beam: An Intense, Cold, and Slow Source for Atoms and Molecules

“…On the other hand, buffer gas beams can be operated with high enough backing pressure such that increasing the pressure further will no longer reduce the beam temperature, without degradation of the beam properties [7,9]. Additionally, for supersonic beams, the introduction of chemically reactive or refractory species is challenging due to the short mean free path between collisions in the source, and are typically introduced into the expansion plume [11,[88][89][90]. This reduces the brightness of the beam.…”

Probing the Electron EDM with Cold Molecules

“…Our experiment uses a cold, pulsed, supersonic beam of YbF radicals [12] in a magnetically shielded vertical vacuum chamber ∼ 1.5m high. The electronic, rotational and vibrational ground state X 2 Σ + 1/2 , N = 0, v = 0 is a hyperfine doublet with states F = 0, 1 split by 170 MHz.…”