7 research outputs found
Measurements of Properties of Antihydrogen
The ALPHA project at the CERN AD is testing fundamental symmetries between matter and antimatter using trapped antihydrogen atoms. The spectrum of the antihydrogen atom may be compared to ordinary hydrogen where it has been measured very precisely. CPT conservation, which underpins our current theoretical framework, requires equality of the masses and charges of matter and its antimatter partners, so antihydrogen spectroscopy presents a path to precision CPT tests. I will discuss the techniques used by ALPHA to trap more than 8000 antihydrogen atoms in 2016, and interrogate them for 600s. The 1S-2S transition in antihydrogen has been observed for the first time, and it agrees with its hydrogen counterpart within an uncertainty of 400 kHz or 0.2 ppb. The charge of the antihydrogen atom has been bounded below . A value of 1420.4 0.5MHz for the hyperfine splitting has been obtained from observation of the positron spin resonance spectrum
Autoresonant Excitation of Antiproton Plasmas
We demonstrate controllable excitation of the center-of-mass longitudinal motion of a thermal antiproton plasma using a swept-frequency autoresonant drive. When the plasma is cold, dense, and highly collective in nature, we observe that the entire system behaves as a single-particle nonlinear oscillator, as predicted by a recent theory. In contrast, only a fraction of the antiprotons in a warm plasma can be similarly excited. Antihydrogen was produced and trapped by using this technique to drive antiprotons into a positron plasma, thereby initiating atomic recombination
Towards antihydrogen trapping and spectroscopy at ALPHA
Spectroscopy of antihydrogen has the potential to yield high-precision tests
of the CPT theorem and shed light on the matter-antimatter imbalance in the
Universe. The ALPHA antihydrogen trap at CERN's Antiproton Decelerator aims to
prepare a sample of antihydrogen atoms confined in an octupole-based Ioffe trap
and to measure the frequency of several atomic transitions. We describe our
techniques to directly measure the antiproton temperature and a new technique
to cool them to below 10 K. We also show how our unique position-sensitive
annihilation detector provides us with a highly sensitive method of identifying
antiproton annihilations and effectively rejecting the cosmic-ray background.Comment: 10 pages, 5 figure
Fundamental Tests of Physics with Antihydrogen at ALPHA
Magnetically trapped antihydrogen atoms at low temperatures were used to test the charge neutrality of this antiatomic system, by precisely placing a limit to its electrical charge. A new method for measuring the gravitational interaction of antimatter was also developed, and prospects for making a precise measurement of this interaction are discussed. Finally, progress towards a precise, direct test of CPT symmetry by laser spectroscopy of antihydrogen is presented