VITO experiment

Last updated
Isotope Separator On Line Device
(ISOLDE)
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
508Solid State Physics Laboratory
The VITO beamline area in the ISOLDE facility VITO experiment.jpg
The VITO beamline area in the ISOLDE facility

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. [1] [2] The beamline is located at the site of the former Ultra High Vacuum (UHV) beamline hosting ASPIC. [3]

Contents

Beamline setup

Radioactive ion beams (RIBs) are produced by the ISOLDE facility, using a beam of high-energy protons from the ProtonSynchrotron Booster (PSB) incident on a target. The interaction of the beam and the target produces radioactive species, which are extracted through thermal diffusion by heating the target. [4] The beam of radioactive ions is then separated by mass number by one of the two mass separators at the facility. [5] The resulting low-energy beam is delivered to the various experimental stations. [6]

The VITO beamline is modular. The first part is common for all projects and is devoted to atomic polarisation via optical pumping with circularly polarised laser light. The singly-charged ion beam of short-lived isotopes from ISOLDE (RIB) is Doppler-tuned in resonance with the laser light provided by a continuous-wave tunable laser. Next, the beam may be neutralised, before it reaches a 1.5 m long section in which the ion or atom beam is overlapped with the laser and they interact many times (many excitation-decay cycles take place), leading to the polarisation of the atomic spins. [2]

The polarised beam is then transported to one of the setups that can be placed behind the polarisation line. At this point the polarised beam is implanted into a solid or liquid host. A strong magnetic field surrounding the sample allowing the nuclear spin polarisation to be maintained for dozens of milliseconds to seconds, by decoupling the electron and nuclear spin. In these conditions, the degree of spin polarisation and its changes can be monitored extremely efficiently by observing the spatial asymmetry in the emission of beta particles by the decaying short-lived nuclei. [7] This is possible, because the weak force that is responsible for the beta decay does not conserve parity. As few as several thousands decays might be enough to record a good signal.

Nuclear Magnetic Resonance (NMR)

Nuclear Magnetic Resonance (NMR) is a technique that provides information on the environment of a nucleus, from calculations based on the shift in Larmor frequency or relaxation time. β-NMR is a modification of this basic technique using the idea that beta decay from polarised radioactive nuclei is anisotropic (directional) in space. The resonances are detected as change in the beta-decay asymmetry which gives it a much higher signal strength than conventional NMR (up to 10 orders of magnitude). [8]

Results

One of the first experiments using polarised beams at VITO was devoted polarisation of a mirror-nucleus argon-35. The scientific motivation for this project was provided by the weak interaction studies and the determination of the Vud matrix element in the CKM quark mixing matrix. [9] [10]

Latest setup for b-NMR at VITO VITO latest.png
Latest setup for β-NMR at VITO

The next, gradually upgraded, setup is centred around a high-field magnet, liquid samples and radio frequency excitations. The aim is to develop a method of beta-detected Nuclear Magnetic Resonance (β-NMR) to investigate the interaction of metal ions with biomolecules in liquids. [11] [12]

The most recent studies at VITO concern the determination of spins and parities in excited nuclear states, poplulated by beta decay. In this case, the setup consists of a solid sample, surrounded by a compact magnet that allows for gamma radiation and neutrons to reach the decay spectroscopy setup. [13]

Related Research Articles

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<span class="mw-page-title-main">TRIUMF</span> Particle physics laboratory in Canada

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.

<span class="mw-page-title-main">ISOLDE</span> Physics facility at CERN

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.

<span class="mw-page-title-main">Argonne Tandem Linear Accelerator System</span> Particle accelerator

The Argonne Tandem Linac Accelerator System (ATLAS) is a U.S. Department of Energy scientific user facility at Argonne National Laboratory. ATLAS is the first superconducting linear accelerator for heavy ions at energies in the vicinity of the Coulomb barrier and is open to scientists from all over the world.

Caesium (55Cs) has 41 known isotopes, the atomic masses of these isotopes range from 112 to 152. Only one isotope, 133Cs, is stable. The longest-lived radioisotopes are 135Cs with a half-life of 1.33 million years, 137
Cs
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He
with a half-life of 806.92(24) milliseconds. The least stable is 10
He
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may have an even shorter half-life.

<span class="mw-page-title-main">Proton Synchrotron Booster</span> CERN particle accelerator

The Proton Synchrotron Booster (PSB) is the first and smallest circular proton accelerator in the accelerator chain at the CERN injection complex, which also provides beams to the Large Hadron Collider. It contains four superimposed rings with a radius of 25 meters, which receive protons with an energy of 160 MeV from the linear accelerator Linac4 and accelerate them up to 2.0 GeV, ready to be injected into the Proton Synchrotron (PS). Before the PSB was built in 1972, Linac 1 injected directly into the Proton Synchrotron, but the increased injection energy provided by the booster allowed for more protons to be injected into the PS and a higher luminosity at the end of the accelerator chain.

<span class="mw-page-title-main">WITCH experiment</span>

WITCH, or experiment IS433, was a double Penning trap experiment to measure the recoil energy of decaying nuclei. A spectrometer in combination with a position-sensitive microchannel plate detector (MCP) was used to count ions while scanning their energy. The experiment was located at the ISOLDE Radioactive Ion Beam Facility in CERN. The beam from ISOLDE was bunched by REXTRAP after which it was transferred to the WITCH set-up.

<span class="mw-page-title-main">Total absorption spectroscopy</span>

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.

<span class="mw-page-title-main">Synchro-Cyclotron (CERN)</span>

The Synchro-Cyclotron, or Synchrocyclotron (SC), built in 1957, was CERN’s first accelerator. It was 15.7 metres (52 ft) in circumference and provided beams 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.

<span class="mw-page-title-main">CERN-MEDICIS</span>

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.

<span class="mw-page-title-main">COLLAPS experiment</span>

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.

<span class="mw-page-title-main">CRIS experiment</span>

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.

<span class="mw-page-title-main">EC-SLI experiment</span>

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.

<span class="mw-page-title-main">ISOLDE Decay Station experiment</span>

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.

<span class="mw-page-title-main">ISOLTRAP experiment</span>

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.

<span class="mw-page-title-main">LUCRECIA experiment</span>

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.

<span class="mw-page-title-main">MIRACLS experiment</span>

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.

<span class="mw-page-title-main">SEC experiment</span>

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.

<span class="mw-page-title-main">WISArD experiment</span> Experimental setup at CERN

The Weak Interaction Studies with 32Ar Decay (WISArD) experiment is a permanent experimental setup located in the ISOLDE facility, at CERN. The purpose of the experiment is to investigate the weak interaction by looking for beta-delayed protons emitted from a nucleus. In the absence of online isotope production during Long Shutdown 2, the experimental setup has also been used to measure the shape of the beta energy spectrum. A goal of the experiment is to search for physics beyond the Standard Model (SM) by expanding the existing limits on currents in the weak interaction.

References

  1. "VITO | ISOLDE". isolde.cern. Retrieved 2023-08-14.
  2. 1 2 Kowalska, M; Aschenbrenner, P; Baranowski, M; Bissell, M L; Gins, W; Harding, R D; Heylen, H; Neyens, G; Pallada, S; Severijns, N; Velten, Ph; Walczak, M; Wienholtz, F; Xu, Z Y; Yang, X F (2017-08-01). "New laser polarization line at the ISOLDE facility" (PDF). Journal of Physics G: Nuclear and Particle Physics. 44 (8): 084005. Bibcode:2017JPhG...44h4005K. doi: 10.1088/1361-6471/aa77d7 . ISSN   0954-3899. S2CID   126306945.
  3. Stachura, Monika; Karl, Johnston; et al. (14 Jan 2015). "VITO setup: Status Report" (PDF). ISOLDE and Neutron Time-of-Flight Experiments Committee.
  4. Peräjärvi, K.; Bergmann, U. C.; Fedoseyev, V. N.; Joinet, A.; Köster, U.; Lau, C.; Lettry, J.; Ravn, H.; Santana-Leitner, M. (2003-05-01). "Studies of release properties of ISOLDE targets". Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms. 14th International Conference on Electromagnetic Isotope Separators and Techniques Related to their Applications. 204: 272–277. Bibcode:2003NIMPB.204..272P. doi:10.1016/S0168-583X(02)01924-9. ISSN   0168-583X. S2CID   97103894.
  5. "ISOLDE isotope separator on-line project". CERN Courier. 7 (2): 22–27. February 1967. Retrieved 26 August 2019.
  6. "ISOLDE". CERN. 2023-07-21. Retrieved 2023-08-15.
  7. Kowalska, Magdalena (2006). Ground state properties of neutron-rich Mg isotopes (Thesis). Johannes Gutenberg-Universität Mainz. doi:10.25358/openscience-4152.
  8. "Beta NMR". Becola. Retrieved 14 Aug 2023.
  9. Gins, W.; Harding, R. D.; Baranowski, M.; Bissell, M. L.; Garcia Ruiz, R. F.; Kowalska, M.; Neyens, G.; Pallada, S.; Severijns, N.; Velten, Ph.; Wienholtz, F.; Xu, Z. Y.; Yang, X. F.; Zakoucky, D. (2019-05-01). "A new beamline for laser spin-polarization at ISOLDE". Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. 925: 24–32. arXiv: 1809.04385 . Bibcode:2019NIMPA.925...24G. doi:10.1016/j.nima.2019.01.082. ISSN   0168-9002. S2CID   119083745.
  10. Gins, Wouter (Jan 2019). "Development of a dedicated laser-polarization beamline for ISOLDE-CERN" (PDF). Ku Leuven.
  11. Kowalska, Magdalena (31 May 2017). "Interaction of Na ions with DNA G-quadruplex structures studied directly with Na beta-NMR spectroscopy". ISOLDE and Neutron Time-of-Flight Experiments Committee.
  12. Karg, Beatrice; Kowalska, Magdalena (4 Jan 2022). "Liquid β-NMR studies of the interaction of Na and K cations with DNA G-quadruplex structures". ISOLDE and Neutron Time-of-Flight Experiments Committee.
  13. Madurga, Miguel; Piersa-Silkowska, Monika (11 Jan 2023). "β-decay spectroscopy with laser-polarised beams of neutron-rich potassium isotopes". ISOLDE and Neutron Time-of-Flight Experiments Committee.