Researchers at the ALPHA experiment at CERN’s Antimatter Factory have achieved an eightfold increase in the production rate of antihydrogen atoms, accumulating over 15,000 atoms in a matter of hours. This advancement, detailed in a recent publication in Nature Communications, utilizes a novel sympathetic cooling technique employing laser-cooled beryllium ions within a Penning trap to reduce positron temperatures to approximately -266 °C. By efficiently cooling positrons prior to merging them with antiprotons, the ALPHA collaboration has significantly accelerated the creation of antihydrogen, a crucial step towards detailed investigation of antimatter properties and behavior. This breakthrough enables more rapid and precise measurements than previously possible.
Antihydrogen Production and the ALPHA Experiment
The ALPHA experiment at CERN’s Antimatter Factory has significantly advanced antihydrogen production through a new positron-cooling technique. Previously considered “science fiction,” the team now produces antihydrogen atoms at an accelerated rate, achieving over 15,000 atoms in under seven hours. This represents an eightfold increase in production speed, dramatically exceeding previous efforts that required ten weeks to accumulate a similar 16,000 atoms for precise spectral measurements.
A key innovation involves “sympathetic cooling,” where a cloud of laser-cooled beryllium ions is added to the positron trap. This process lowered the positron cloud’s temperature to around -266 °C, enhancing the efficiency of antihydrogen atom formation when mixed with antiprotons. Over the 2023–24 experimental runs, the ALPHA experiment utilized this technique to produce over 2 million antihydrogen atoms, paving the way for more detailed investigations.
This breakthrough allows for faster and more precise measurements of antimatter, addressing systematic uncertainties in experiments. Researchers can now accumulate antihydrogen overnight and measure spectral lines the following day. Currently, the ALPHA experiment is leveraging these unprecedented atom numbers to study the effect of gravity on antimatter as part of the ALPHA-g experiment, furthering our understanding of this elusive substance.
Cooling Positrons for Enhanced Antihydrogen Formation
The ALPHA experiment at CERN significantly enhanced antihydrogen production by implementing a new positron cooling technique. Previously, positrons were confined in a Penning trap, but retained too much energy for efficient antihydrogen formation. Researchers introduced laser-cooled beryllium ions to the trap, enabling “sympathetic cooling” and reducing the positron cloud temperature to approximately -266 °C. This advancement increased the rate of antihydrogen production eightfold, allowing for the accumulation of over 15,000 atoms in just a matter of hours.
This improved cooling method allows for significantly more antihydrogen atoms to be produced in a shorter timeframe. Prior experiments required ten weeks to accumulate 16,000 antihydrogen atoms for precision spectral measurements. With the new technique, the ALPHA team accumulated over 2 million antihydrogen atoms during the 2023–24 experimental runs. This speed is critical for investigating systematic uncertainties and performing rapid measurements of spectral lines.
The ability to accumulate large quantities of antihydrogen quickly is enabling new research directions. Researchers are now using the increased atom numbers to study the effect of gravity on antimatter as part of the ALPHA-g experiment. The ALPHA collaboration anticipates even more precise measurements and deeper insights into the properties and behavior of this elusive form of matter thanks to the refined positron cooling process.
Investigating Antimatter Properties with Increased Atom Numbers
The ALPHA experiment at CERN has significantly advanced antimatter research through a new positron cooling technique. This method, employing laser-cooled beryllium ions, reduced the positron cloud temperature to around -266 °C. The result was an eightfold increase in the production rate of antihydrogen atoms – the simplest form of antimatter – allowing over 15,000 atoms to be accumulated in under seven hours, a process that previously took ten weeks to achieve similar numbers.
This breakthrough in antihydrogen production is crucial for detailed investigation. Researchers can now accumulate sufficient atoms “overnight” to measure spectral lines the following day, enabling faster and more precise measurements. Over the course of 2023-24, the ALPHA experiment created over 2 million antihydrogen atoms, highlighting the efficiency of the refined cooling process and opening opportunities for deeper probing into antimatter’s properties.
Currently, the unprecedented numbers of antihydrogen atoms are being utilized to study the effect of gravity on antimatter as part of the ALPHA-g experiment. The improved production rate is a “real game-changer” for minimizing systematic uncertainties in measurements, ultimately allowing scientists to investigate atomic antimatter with greater precision and explore its fundamental behavior.
With larger numbers of antihydrogen atoms now more readily available, we can investigate atomic antimatter in greater detail and at a faster pace than before.
Jeffrey Hangst
