Noise Reduction for ALPHA-g Magnet Control System

According to the Standard Model and CPT theory, antimatter and matter should have been made in equal amounts during the Big Bang, but the world we live in is only regular matter. By comparing the precision of hydrogen measurements to that of antihydrogen (H), experiments can put limits on CPT and refine current theory. The Antimatter Laser PHysics Apparatus (ALPHA) at CERN's Antiproton Decelerator (AD) Hall is currently studying this phenomenon by mixing antiprotons from the Proton Synchrotron with positrons generated from Na-22 to create and trap antihydrogen. ALPHA consists of two experiments: ALPHA-2, which specializes in antihydrogen spectroscopy using lasers, and ALPHA-g, which studies the affects of gravity on H. n 2023, ALPHA-g published preliminary results showing antihydrogen fell with the same gravitational acceleration as hydrogen. Currently, ALPHA-g is undergoing upgrades to make this measurement more precise. To make better measurements, precision magnets are being added to the apparatus in addition to other upgraded hardware. These new magnets, in addition with all the other ALPHA magnets, are controlled by the Magnet Control System (MCS). the PS controller consists of two compact RIOs (cRIOs) acting as a PID controller to modulate the current in the superconducting magnets. The signal is sent to the power supply (PS), which then sends a signal to the Quench Protection System (QPS). The QPS is able to keep the entire system safe if the magnet quenches by distributing heat throughout several circuit elements. Assuming no quenches are occurring, the current from the QP is sent to the magnet to control the magnetic field in the apparatus. The current in the magnet is measured using a direct current-current transformer (DCCT), which sends the signal back into the PS controller. Since it is also a PID controller, any deviations in the measured current from the expected current is fixed, and a new signal is sent out again. Unfortunately, physics is still unable to predict exactly when a superconducting magnet will quench. Thus, the MCS must be sensitive enough to detect even the slightest change in current in the system to activate the QPS in time to protect the rest of the system. This means the MCS is very sensitive to noise, and unfortunately, adding new magnets during upgrades to the system adds more noise. To keep noise to a minimum regardless of the magnets in the system, a circuit can be introduced between the DCCT and PS controller. This circuit will have a relatively low current because the magnet will be superconducting while the system is on, and when introduced, must not add any more noise to the system. The goal for this summer was to design, build, and test the noise-reduction abilities of this circuit in a mock MCS setup.