A large sample study of spin relaxation and magnetometric sensitivity of paraffin-coated Cs vapor cells

Abstract

We have manufactured more than 250 nominally identical paraffin-coated Cs vapor cells (30 mm diameter bulbs) for multi-channel atomic magnetometer applications. We describe our dedicated cell characterization apparatus. For each cell we have determined the intrinsic longitudinal, Γ 01 , and transverse, Γ 02 , relaxation rates. Our best cell shows Γ 01 /2π ≈ 0.5 Hz, and Γ 02 /2π ≈ 2 Hz. We find a strong correlation of both relaxation rates which we explain in terms of reservoir and spin exchange relaxation. For each cell we have determined the optimal combination of rf and laser powers which yield the highest sensitivity to magnetic field changes. Out of all produced cells, 90% are found to have magnetometric sensitivities in the range of 9 to 30 fT/ √ Hz. Noise analysis shows that the magnetometers operated with such cells have a sensitivity close to the fundamental photon shot noise limit.

A quantitative study of particle size effects in the magnetorelaxometry of magnetic nanoparticles using atomic magnetometry

“…Each magnetometer uses optically detected magnetic resonance in room temperature Cs vapour that is contained in a paraffin-coated [28] 30 mm diameter Pyrex bulb. In its M x -mode of operation [29] each sensor produces an oscillatory voltage, V i (t), that represents the photocurrent from a photodiode detecting the laser power transmitted by the cell.…”

Light effects in the atomic-motion-induced Ramsey narrowing of dark resonances in wall-coated cells

“…We use a cylindrical cell which has the external diameter and length both equal to 14 mm and is filled with isotopically enriched 87 Rb (hyperfine separation ν hf = 6.834 682 610 GHz). The internal walls of the cell are coated with Paraflint, a commercial paraffin well known for its particularly good antirelaxation properties [25,26]. We monitor the light transmitted through the cell when the detuning between two resonant frequencies in the laser spectrum (i.e., the Raman detuning δ R ) is swept around ν hf .…”

“…(1) to our experimental data. In the case of an atomic system contained in an evacuated wall-coated cell, is limited by the atom-wall coating collisions [25,36], the spin-exchange collisions [37], and the contribution from the atoms escaping through the Rb reservoir [26]. We evaluated the contribution of the spin-exchange and the reservoir losses to be of the order of a few tens of hertz and a few hertz, respectively.…”

Subfemtotesla Scalar Atomic Magnetometry Using Multipass Cells

“…The sensitivity of scalar magnetometers has been relatively poor, as summarized recently in [11]. The best directly measured scalar magnetometer sensitivity is equal 7 fT/Hz 1/2 with a measurement volume of 1.5 cm 3 [12], while estimates of fundamental sensitivity per unit measurement volume for various types of scalar alkali-metal magnetometers range from several fT cm 3/2 /Hz 1/2 [13,14] to about 1 fT cm 3/2 /Hz 1/2 [12]. Here we describe a new type of scalar atomic magnetometer using multi-pass vapor cells [15,16] and operating in a pulsed pump-probe mode [17] to achieve magnetic field sensitivity of 0.54 fT/Hz 1/2 with a measurement volume of 0.66 cm 3 in each multi-pass cell.…”