Light shift averaging in paraffin-coated alkali vapor cells

Light shifts are an important source of noise and systematics in optically pumped magnetometers. We demonstrate that the long spin coherence time in paraffin-coated cells leads to spatial averaging of the light shifts over the entire cell volume. This renders the averaged light shift independent, under certain approximations, of the light-intensity distribution within the sensor cell. These results and the underlying mechanism can be extended to other spatially varying phenomena in anti-relaxation-coated cells with long coherence times.Comment: 6 pages, 4 figure

Vector AC Stark shift in 133Cs atomic magnetometers with antirelaraxion coated cells

The main focus of this dissertation is investigation of vector AC Stark shifts (light shifts) in evacuated 133Cs paraffin-coated cells. Although light shifts in alkali atoms have been investigated since 1960s, the effect of laser-induced vector light shifts (VLS) in paraffin-coated cells is little explored in literature. The works considering light shift effects primarily focus on transitions relevant for atomic clocks, or magnetometers using buffer gas cells, or magnetometers using broad-spectrum alkali metal lamps. This work, on the other hand, focuses on light shifts in a setup shared by finite-field optical magnetometers that use paraffin-coated sensor cells, as well as on their impact on sensitivity and accuracy of these devices.Along with describing the light shifts, this work presents several techniques that take advantage of the VLS to improve atomic magnetometers as a tool. The proposed techniques eliminate the need for oscillating radio-frequency magnetic fields and replace them with well contained laser beams. This can benefit applications where non-magnetic sensors are needed and stray fields are highly undesirable, such as the search for a permanent electric dipole moment of the neutron.This dissertation includes two such projects, the all-optical vector magnetometer and the rf magnetometer driven by a fictitious magnetic field. In the first project a finite-field optical magnetometer, which is normally a scalar sensor, is augmented with two power-modulated orthogonal laser beams that provide the directional sensitivity. The sensor exhibits a demonstrated rms noise floor of 50 fT/√Hz in measurement of the field magnitude and 0.5 mrad/√Hz in the field direction. Elimination of technical noise would improve these sensitivities to 12 fT/√Hz and 5 μrad/√Hz, respectively. In the second project, the atomic precession in a scalar 133Cs magnetometer is driven by an effective oscillating magnetic field provided by the AC Stark shift of an intensity-modulated laser beam. The demonstrated sensitivity of this magnetometer is 40 fT/√Hz rms, which is equivalent to the conventional coil-driven scalar magnetometer we built sharing the same setup.The Appendix includes documentation on the custom-built polarimeter used in the experiments and the frequency response of the magnetic sensor head

Hardware Design of the Generic Rear Transition Module for the Global Trigger System of the ATLAS Phase II Upgrade

The High-Luminosity Large Hadron Collider (HL-LHC) is expected to start operations in the middle of 2027, to deliver more than ten times the integrated luminosity of the LHC Runs 1-3 combined (up to 4000 fb−1). Meeting these requirements poses significant challenges to the hardware design of the Trigger and Data Acquisition (TDAQ) system. Global Trigger is a new subsystem in the ATLAS Phase-II upgrade, which will bring event filter-like capability to the Level-0 trigger system. A common hardware platform in Advanced Telecommunications Computing Architecture (ATCA) form factor named Global Common Module (GCM) is proposed to be configured as processor nodes in the Global Trigger. To mitigate the risk and simplify the GCM hardware design, a Generic Rear Transition Module (GRM) is being developed. GRM, which has been implemented with a Xilinx Versal Prime FPGA and sufficient multi-gigabit transceivers, aims at system control and communication with the Front-End Link eXchange (FELIX). It could also provide additional processing or readout capacity

A network of magnetometers for multi-scale urban science and informatics

Abstract. The magnetic signature of an urban environment is investigated using a geographically distributed network of fluxgate magnetometers deployed in and around Berkeley, California. The system hardware and software are described and initial operations of the network are reported. The sensors measure vector magnetic fields at a 3960 Hz sample rate and are sensitive to 0.1 nT/Hz. Data from individual stations are synchronized to ±120 µs using global positioning system (GPS) and computer system clocks and automatically uploaded to a central server. We present the initial observations of the network and preliminary efforts to correlate sensors. A wavelet analysis is used to study observations of the urban magnetic field over a wide range of temporal scales. The Bay Area Rapid Transit (BART) is identified as the dominant signal in our observations, exhibiting aspects of both broadband noise and coherent periodic features. Significant differences are observed in both day–night and weekend–weekday signatures. A superposed epoch analysis is used to study and extract the BART signal. </jats:p

Is light narrowing possible with dense-vapor paraffin coated cells for atomic magnetometers?

We investigated the operation of an all-optical rubidium-87 atomic magnetometer with amplitude-modulated light. To study the suppression of spin-exchange relaxation, three schemes of pumping were implemented with room-temperature and heated paraffin coated vacuum cells. Efficient pumping and accumulation of atoms in the F=2 ground state were obtained. However, the sought-for narrowing of the resonance lines has not been achieved. A theoretical analysis of the polarization degree is presented to illustrate the absence of light narrowing due to radiation trapping at high temperature

Multiplexing Firmware Prototypes for the Global Trigger System of the ATLAS Phase-II Upgrade

The Global Trigger will be introduced in the ATLAS experiment Phase-II Trigger Upgrade to evaluate data from all sub-detectors at every bunch-crossing. This requires the handling of data with different rates, latencies and protocols. Different flavors of firmware will be developed to time-multiplex and aggregate data within an event, from up to 72 input optical channels per instance, and to convey that data to one of the Global Event Processor nodes to process that particular event