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. [1] The experiment has been operating since the late 1970s, and is the oldest active experiment at ISOLDE. [2] [3]
List of ISOLDE experimental setups | |
---|---|
COLLAPS, CRIS, EC-SLI, IDS, ISS, ISOLTRAP, LUCRECIA, Miniball, MIRACLS, SEC, VITO, WISArD | |
Other facilities | |
MEDICIS | Medical Isotopes Collected from ISOLDE |
508 | Solid State Physics Laboratory |
The technique of collinear spectroscopy was developed in the mid-1970s by S.L. Kaufman. [4] This describes a method of obtaining narrow absorption lines, specifically providing a sensitivity ideal for experiments on short-lived isotopes.
Two beams are used in the technique: a laser beam sent through the sample, and a probe beam. The alignment of both beams collinearly (along the same path) allow for control of the time and spatial overlap. [5] This enables investigation into the nuclear properties of the sample simultaneously. [6]
COLLAPS is located within the ISOLDE facility at CERN, giving it access to the radioactive ions produced by ISOLDE's resonance ionisation laser ion source (RILIS). [7] The ions are delivered to the COLLAPS beamline and are excited using tunable continuous-wave lasers through the technique of collinear spectroscopy. [8] [9] The laser systems produce laser light in the 210 nm to 1000 nm range with a narrow linewidth. The systems allow access to the atomic transitions necessary for the short-lived nuclei produced by ISOLDE. [3]
Laser spectroscopy is better performed on a neutral atom, and therefore a charge exchange cell (CEC) is needed to neutralise the ionic beam from ISOLDE. [7] A CEC neutralises the ions by causing the ionic beam to collide with the alkali vapours in the cell and transfer charge. Prior to entering the CEC, the ions are reaccelerated (retarded) and a scan of the atomic transition is taken using Doppler-tuning electrodes. [10] Laser spectroscopy is then performed on the neutral atom, however can also be performed directly on the ion. The detection system, located at the end of the beamline, consists of eight large-diameter aspheric lenses. [3] The atoms de-excite and release fluorescent light, which is transferred to the four photomultiplier tubes (PMTs) by the lenses.
The following are some notable results from the COLLAPS experiment. [11] [3]
Isotope separation is the process of concentrating specific isotopes of a chemical element by removing other isotopes. The use of the nuclides produced is varied. The largest variety is used in research. By tonnage, separating natural uranium into enriched uranium and depleted uranium is the largest application. In the following text, mainly uranium enrichment is considered. This process is crucial in the manufacture of uranium fuel for nuclear power plants and is also required for the creation of uranium-based nuclear weapons. Plutonium-based weapons use plutonium produced in a nuclear reactor, which must be operated in such a way as to produce plutonium already of suitable isotopic mix or grade.
TRIUMF is Canada's national particle accelerator centre. It is considered Canada's premier physics laboratory, and consistently regarded as one of the world's leading subatomic physics research centres. Owned and operated by a consortium of universities, it is on the south campus of one of its founding members, the University of British Columbia in Vancouver, British Columbia, Canada. It houses the world's largest normal conducting cyclotron, a source of 520 MeV protons, which was named an IEEE Milestone in 2010. Its accelerator-focused activities involve particle physics, nuclear physics, nuclear medicine, materials science, and detector and accelerator development.
In nuclear physics, an atomic nucleus is called a halo nucleus or is said to have a nuclear halo when it has a core nucleus surrounded by a "halo" of orbiting protons or neutrons, which makes the radius of the nucleus appreciably larger than that predicted by the liquid drop model. Halo nuclei form at the extreme edges of the table of nuclides — the neutron drip line and proton drip line — and have short half-lives, measured in milliseconds. These nuclei are studied shortly after their formation in an ion beam.
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.
Helium (2He) has nine known isotopes, but only helium-3 (3He) and helium-4 (4He) are stable. All radioisotopes are short-lived; the longest-lived is 6He with half-life 806.92(24) milliseconds. The least stable is 10He, with half-life 260(40) yoctoseconds, though 2He may have an even shorter half-life.
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.
Klaus Blaum is a German physicist and director at the Max Planck Institute for Nuclear Physics in Heidelberg, Germany.
Total absorption spectroscopy is a measurement technique that allows the measurement of the gamma radiation emitted in the different nuclear gamma transitions that may take place in the daughter nucleus after its unstable parent has decayed by means of the beta decay process. This technique can be used for beta decay studies related to beta feeding measurements within the full decay energy window for nuclei far from stability.
The Synchro-Cyclotron, or Synchrocyclotron (SC), built in 1957, was CERN’s first accelerator. It was in circumference and provided for CERN's first experiments in particle and nuclear physics. It accelerated particles to energies up to 600 MeV. The foundation stone of CERN was laid at the site of the Synchrocyclotron by the first Director-General of CERN, Felix Bloch. After its remarkably long 33 years of service time, the SC was decommissioned in 1990. Nowadays it accepts visitors as an exhibition area in CERN.
CERN-MEDical Isotopes Collected from ISOLDE (MEDICIS) is a facility located in the Isotope Separator Online DEvice (ISOLDE) facility at CERN, designed to produce high-purity isotopes for developing the practice of patient diagnosis and treatment. The facility was initiated in 2010, with its first radioisotopes (terbium-155) produced on 12 December 2017.
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 Emission Channeling with Short-Lived Isotopes (EC-SLI) experiment is a permanent setup located within the ISOLDE facility and CERN. The purpose of the experiment is to study lattice locations of dopants and impurities in both single crystals and epitaxial thin films. The experiment uses short-lived isotopes from the ISOLDE on-line beamline, as well as longer-lived isotopes from three off-line beamlines.
The ISOLDE Decay Station (IDS) is a permanent experiment located in the ISOLDE facility at CERN. The purpose of the experiment is to measure decay properties of radioactive isotopes using spectroscopy techniques for a variety of applications, including nuclear engineering and astrophysics. The experimental setup has been operational since 2014.
The ISOLDE Solenoidal Spectrometer (ISS) experiment is a permanent experimental setup located in the ISOLDE facility at CERN. By using an ex-MRI magnet, heavy radioactive ion beams (RIBs) produced by the HIE-ISOLDE post-accelerator are directed at a light target and the kinematics of the reaction is measured. The purpose of the experiment is to measure properties of atomic nuclei replicating the conditions present in some astrophysical processes, such as the production of chemical elements in stars. The experiment will also produce results that provide a better understanding of nucleon-nucleon interactions in highly-unstable, very radioactive (exotic) nuclei.
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.
The LUCRECIA experiment is a permanent experimental setup at the ISOLDE facility at CERN. The purpose of LUCRECIA is to analyse nuclear structure and use this to confirm theoretical models and make stellar predictions. The experiment is based on a Total Absorption gamma Spectrometer (TAS) designed to measure beta ray feeding.
The Miniballexperiment is a gamma-ray spectroscopy setup regularly located in the ISOLDE facility at CERN, along with other locations including GSI, Cologne, PSI and RIKEN (HiCARI). Miniball is a high-resolution germanium detector array, specifically designed to work with low-intensity radioactive ion beams post-accelerated by HIE-ISOLDE, to analyse gamma radiation emitted by short-lived nuclei. Due to six-fold detector segmentation, Miniball offers a superior Doppler-correction capability with respect to conventional gamma-ray spectrometers using unsegmented detectors. The array has been used for successful Coulomb-excitation and transfer-reaction experiments with exotic beams. Results from Miniball experiments have been used to determine and probe nuclear structure.
The Multi Ion Reflection Apparatus for Colinear Laser Spectroscopy (MIRACLS) is a permanent experiment setup being constructed at the ISOLDE facility at CERN. The purpose of the experiment is to measure properties of exotic radioisotopes, from precise measurements of their hyperfine structure. MIRACLS will use laser spectroscopy for measurements, aiming to increase the sensitivity of the technique by trapping ion bunches in an ion trap.
The Scattering Experiments Chamber (SEC) experiment is a permanent experimental setup located in the ISOLDE facility at CERN. The station facilitates diversified reaction experiments, especially for studying low-lying resonances in light atomic nuclei via transfer reactions. SEC does not detect gamma radiation, and therefore is complementary to the ISOLDE Solenoidal Spectrometer (ISS) and Miniball experiments.
The Versatile Ion polarisation Technique Online (VITO) experiment is a permanent experimental setup located in the ISOLDE facility at CERN, in the form of a beamline. The purpose of the beamline is to perform a wide range of studies using spin-polarised short-lived atomic nuclei. VITO uses circularly-polarised laser light to obtain polarised radioactive beams of different isotopes delivered by ISOLDE. These have already been used for weak-interaction studies, biological investigations, and more recently nuclear structure research. The beamline is located at the site of the former Ultra High Vacuum (UHV) beamline hosting ASPIC.
{{cite web}}
: CS1 maint: bot: original URL status unknown (link)