A team of scientists at the Rice University have discovered the heaviest antimatter particle known as antihelium-4. This newly found antimatter particle is derived from the helium nucleus. Physicists at Bonner Lab of Rice University created the new time-of-flight detector, which identified antihelium-4.
Countries such as U.S. and China had teamed up to design and develop the detector, which is valued at $7.5 million. Scientists from China offered a financial support of $2.5 million to the project. The detector was set up at the Relativistic Heavy Ion Collider (RHIC) in New York. The installation was part of the STAR (Solenoidal Tracker) experiment.
Fifteen antihelium-4 nuclei were observed after setting up the time-of-flight detector. Antihelium-4 particles were formed as a result of collision of heavy gold ions at approximately the speed of light. It was found that the nuclei include two antineutrons and two antiprotons and did not experience radioactive decay.
The heavy gold ions collided to generate quark gluon plasma. On cooling this plasma, a hadron gas containing neutrons, protons, and antimatter equivalents was formed along with other basic particles. Antihelium-4 was first spotted in this cloud of particles, which were expanding rapidly.
The detector comprises 23,000 sensors that envelope STAR. These sensors are useful in detecting which type of subatomic particles is released upon nuclei collision. Researchers can use the detector to measure the time taken by a particle to travel from its origin to the point it passes via one of the sensors. The detector has an accuracy of a 10th of a billionth of a second.
Source: http://www.rice.edu/