High-accuracy spectroscopic comparisons of trapped antihydrogen atoms (H¯) and hydrogen atoms (H) promise to stringently test the fundamental CPT symmetry invariance of the standard model of particle ...physics. ATRAP’s nested Penning-Ioffe trap was developed for such studies. The first of its unique features is that its magnetic Ioffe trap for H¯atoms can be switched between quadrupole and octupole symmetries. The second is that it allows laser and microwave access perpendicular to the central axis of the traps.
Trapped antihydrogen in its ground state Gabrielse, G; Kalra, R; Kolthammer, W S ...
Physical review letters,
03/2012, Letnik:
108, Številka:
11
Journal Article
Recenzirano
Odprti dostop
Antihydrogen atoms (H¯) are confined in an Ioffe trap for 15-1000 s-long enough to ensure that they reach their ground state. Though reproducibility challenges remain in making large numbers of cold ...antiprotons (p¯) and positrons (e(+)) interact, 5±1 simultaneously confined ground-state atoms are produced and observed on average, substantially more than previously reported. Increases in the number of simultaneously trapped H¯ are critical if laser cooling of trapped H¯ is to be demonstrated and spectroscopic studies at interesting levels of precision are to be carried out.
For the first time a single trapped antiproton (p) is used to measure the p magnetic moment μ(p). The moment μ(p)=μ(p)S/(ℏ/2) is given in terms of its spin S and the nuclear magneton (μ(N)) by ...μ(p)/μ(N)=-2.792 845±0.000 012. The 4.4 parts per million (ppm) uncertainty is 680 times smaller than previously realized. Comparing to the proton moment measured using the same method and trap electrodes gives μ(p)/μ(p)=-1.000 000±0.000 005 to 5 ppm, for a proton moment μ(p)=μ(p)S/(ℏ/2), consistent with the prediction of the CPT theorem.
Taking advantage of both the high mass resolution of the COSY-11 detector and the high energy resolution of the low-emittance proton beam of the cooler synchrotron COSY, we determine the excitation ...function for the pp→ppη(') reaction close to threshold. Combining these data with previous results, we extract the scattering length for the η(')-proton potential in free space to be Re(a(pη(')))=0±0.43 fm and Im(a(pη(')))=0.37(-0.16)(+0.40) fm.
The proton–proton elastic differential cross section at very small four momentum transfer squared has been measured at three different incident proton momenta in the range of 2.5 to 3.2 GeV/c by ...detecting the recoil proton at polar angles close to 90∘. The measurement was performed at COSY with the KOALA detector covering the Coulomb–nuclear interference region. The total cross section σtot, which has been determined precisely, is consistent with previous measurements. The values of the slope parameter B and the relative real amplitude ratio ρ determined in this experiment alleviate the lack of data in the relevant energy region. These precise data on ρ might be an important check for a new dispersion analysis.
Lasers are used for the first time to control the production of antihydrogen (H ). Sequential, resonant charge exchange collisions are involved in a method that is very different than the only other ...method used so far-producing slow H during positron cooling of antiprotons in a nested Penning trap. Two attractive features are that the laser frequencies determine the H binding energy, and that the production of extremely cold H should be possible in principle-likely close to what is needed for confinement in a trap, as needed for precise laser spectroscopy.
A background-free observation of cold antihydrogen atoms is made using field ionization followed by antiproton storage, a detection method that provides the first experimental information about ...antihydrogen atomic states. More antihydrogen atoms can be field ionized in an hour than all the antimatter atoms that have been previously reported, and the production rate per incident high energy antiproton is higher than ever observed. The high rate and the high Rydberg states suggest that the antihydrogen is formed via three-body recombination.
PDF
