Antihydrogen is the antimatter counterpart of hydrogen. Whereas the common hydrogen atom is composed of an electron and proton, the antihydrogen atom is made up of a positron and antiproton. Scientists hope that studying antihydrogen may shed light on the question of why there is more matter than antimatter in the observable universe, known as the baryon asymmetry problem. Antihydrogen is produced artificially in particle accelerators.
Laser cooling includes a number of techniques where atoms, molecules, and small mechanical systems are cooled with laser light. The directed energy of lasers is often associated with heating materials, e.g. laser cutting, so it can be counterintuitive that laser cooling often results in sample temperatures approaching absolute zero. Laser cooling relies on the change in momentum when an object, such as an atom, absorbs and re-emits a photon. For example, if laser light illuminates a warm cloud of atoms from all directions and the laser's frequency is tuned below an atomic resonance, the atoms will be cooled. This common type of laser cooling relies on the Doppler effect where individual atoms will preferentially absorb laser light from the direction opposite to the atom's motion. The absorbed light is re-emitted by the atom in a random direction. After repeated emission and absorption of light the net effect on the cloud of atoms is that they will expand more slowly. The slower expansion reflects a decrease in the velocity distribution of the atoms, which corresponds to a lower temperature and therefore the atoms have been cooled. For an ensemble of particles, their thermodynamic temperature is proportional to the variance in their velocity. More homogeneous velocities between particles corresponds to a lower temperature. Laser cooling techniques combine atomic spectroscopy with the aforementioned mechanical effect of light to compress the velocity distribution of an ensemble of particles, thereby cooling the particles.
Mass spectrometry (MS) is an analytical technique that is used to measure the mass-to-charge ratio of ions. The results are presented as a mass spectrum, a plot of intensity as a function of the mass-to-charge ratio. Mass spectrometry is used in many different fields and is applied to pure samples as well as complex mixtures.
In atomic physics, hyperfine structure is defined by small shifts in otherwise degenerate energy levels and the resulting splittings in those energy levels of atoms, molecules, and ions, due to electromagnetic multipole interaction between the nucleus and electron clouds.
A microprobe is an instrument that applies a stable and well-focused beam of charged particles to a sample.
The ISOLDE Radioactive Ion Beam Facility, is an on-line isotope separator facility located at the centre of the CERN accelerator complex on the Franco-Swiss border. Created in 1964, the ISOLDE facility started delivering radioactive ion beams (RIBs) to users in 1967. Originally located at the Synchro-Cyclotron (SC) accelerator, the facility has been upgraded several times most notably in 1992 when the whole facility was moved to be connected to CERN's ProtonSynchroton Booster (PSB). ISOLDE is currently the longest-running facility in operation at CERN, with continuous developments of the facility and its experiments keeping ISOLDE at the forefront of science with RIBs. ISOLDE benefits a wide range of physics communities with applications covering nuclear, atomic, molecular and solid-state physics, but also biophysics and astrophysics, as well as high-precision experiments looking for physics beyond the Standard Model. The facility is operated by the ISOLDE Collaboration, comprising CERN and sixteen (mostly) European countries. As of 2019, close to 1,000 experimentalists around the world are coming to ISOLDE to perform typically 50 different experiments per year.
A trapped-ion quantum computer is one proposed approach to a large-scale quantum computer. Ions, or charged atomic particles, can be confined and suspended in free space using electromagnetic fields. Qubits are stored in stable electronic states of each ion, and quantum information can be transferred through the collective quantized motion of the ions in a shared trap. Lasers are applied to induce coupling between the qubit states or coupling between the internal qubit states and the external motional states.
A radio-frequency quadrupole (RFQ) beam cooler is a device for particle beam cooling, especially suited for ion beams. It lowers the temperature of a particle beam by reducing its energy dispersion and emittance, effectively increasing its brightness (brilliance). The prevalent mechanism for cooling in this case is buffer-gas cooling, whereby the beam loses energy from collisions with a light, neutral and inert gas. The cooling must take place within a confining field in order to counteract the thermal diffusion that results from the ion-atom collisions.
Electron beam ion trap (EBIT) is an electromagnetic bottle that produces and confines highly charged ions. An EBIT uses an electron beam focused with a powerful magnetic field to ionize atoms to high charge states by successive electron impact.
A nuclear clock or nuclear optical clock is a notional clock that would use the frequency of a nuclear transition as its reference frequency, in the same manner as an atomic clock uses the frequency of an electronic transition in an atom's shell. Such a clock is expected to be more accurate than the best current atomic clocks by a factor of about 10, with an achievable accuracy approaching the 10−19 level. The only nuclear state suitable for the development of a nuclear clock using existing technology is thorium-229m, a nuclear isomer of thorium-229 and the lowest-energy nuclear isomer known. With an energy of about 8 eV, the corresponding ground-state transition is expected to be in the vacuum ultraviolet wavelength region around 150 nm, which would make it accessible to laser excitation. A comprehensive review can be found in reference.
A particle accelerator is a machine that uses electromagnetic fields to propel charged particles to very high speeds and energies, and to contain them in well-defined beams.
Atomic Spectroscopy and Collisions Using Slow Antiprotons (ASACUSA), AD-3, is an experiment at the Antiproton Decelerator (AD) at CERN. The experiment was proposed in 1997, started collecting data in 2002 by using the antiprotons beams from the AD, and will continue in future under the AD and ELENA decelerator facility.
Saturated absorption spectroscopy measures the transition frequency of an atom or molecule between its ground state and an excited state. In saturated absorption spectroscopy, two counter-propagating, overlapped laser beams are sent through a sample of atomic gas. One of the beams stimulates photon emission in excited atoms or molecules when the laser's frequency matches the transition frequency. By changing the laser frequency until these extra photons appear, one can find the exact transition frequency. This method enables precise measurements at room temperature because it is insensitive to doppler broadening. Absorption spectroscopy measures the doppler-broadened transition, so the atoms must be cooled to millikelvin temperatures to achieve the same sensitivity as saturated absorption spectroscopy.
In atomic physics, Raman cooling is a sub-recoil cooling technique that allows the cooling of atoms using optical methods below the limitations of Doppler cooling, Doppler cooling being limited by the recoil energy of a photon given to an atom. This scheme can be performed in simple optical molasses or in molasses where an optical lattice has been superimposed, which are called respectively free space Raman cooling and Raman sideband cooling. Both techniques make use of Raman scattering of laser light by the atoms.
Peter E. Toschek was a German experimental physicist who researched nuclear physics, quantum optics, and laser physics. He is known as a pioneer of laser spectroscopy and for the first demonstration of single trapped atoms (ions). He was a professor at Hamburg University.
Resonance ionization is a process in optical physics used to excite a specific atom beyond its ionization potential to form an ion using a beam of photons irradiated from a pulsed laser light. In resonance ionization, the absorption or emission properties of the emitted photons are not considered, rather only the resulting excited ions are mass-selected, detected and measured. Depending on the laser light source used, one electron can be removed from each atom so that resonance ionization produces an efficient selectivity in two ways: elemental selectivity in ionization and isotopic selectivity in measurement.
The COLinear LAser SPectroscopy (COLLAPS) experiment is located in the ISOLDE facility at CERN. The purpose of the experiment is to investigate ground and isomeric state properties of exotic, short lived nuclei, including spins, electro-magnetic moments and charge radii. The experiment has been operating since the late 1970s, and is the oldest active experiment at ISOLDE.
The Collinear Resonance Ionization Spectroscopy (CRIS) experiment is located in the ISOLDE facility at CERN. The experiment aims to study ground-state properties of exotic nuclei and produce high purity isomeric beams used for decay studies. CRIS does this by using the high resolution technique of fast beam collinear laser spectroscopy, with the high efficiency technique of resonance ionization.
The high-precision mass spectrometer ISOLTRAP experiment is a permanent experimental setup located at the ISOLDE facility at CERN. The purpose of the experiment is to make precision mass measurements using the time-of-flight (ToF) detection technique. Studying nuclides and probing nuclear structure gives insight into various areas of physics, including astrophysics.
