CRIS experiment

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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
MEDICISMedical Isotopes Collected from ISOLDE
508Solid State Physics Laboratory
The Collinear Resonance Ionization Spectroscopy (CRIS) 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.[1][2]

Background

The technique of fast beam collinear resonance ionization spectroscopy is a merger of two traditional approaches to laser spectroscopy: in-source resonance ionization spectroscopy and fluorescence-detection fast beam collinear laser spectroscopy.[3]

Resonance ionization spectroscopy is based on stepwise

ionization potential of the element. The element can then be ionized to an autoionising state or non-resonant ionization state.[4][5] The technique allows for an elemental selectivity in ionization and isotopic selectivity in measurement, as other elements will not be affected by the tuned laser light.[6]

Fluorescence-detection fast beam collinear laser spectroscopy is a high-resolution technique that resolves the hyperfine structure and isotope shift of an atomic transition.[7] This is done by superimposing two beams, an ionic or atomic beam and a tuned narrow-bandwidth laser beam. At resonance, the beam is scanned and fluorescent photons are emitted and collected by a photon detector.[8] The fast beam used in this technique limits the distribution of kinetic energies, and reduces the Doppler broadening of the resonance peak.[9]

Experimental setup

CRIS beamline in the ISOLDE facility at CERN

CRIS bends bunched radioactive beams that have been accelerated, mass separated and cooled to room temperature, produced by the ISOLDE facility and directs them to overlap in space and time with the pulsed laser beams.[1] An alkali-filled charge exchange cell (CEC) is used to neutralise the ion beam, before it is directed through a differential pumping region and deflector plates.[10] Here, the residual ions that weren't neutralised are deflected and dumped, and the neutral beam proceeds to the interaction region, kept at ultra high vacuum (10−10 mbar).[11][12]

In the interaction region, the atoms are resonantly ionized by the lasers and then deflected through horizontal and vertical deflection plates. Scanning the narrow frequency band of the lasers, while monitoring the ion count rate yields a spectrum of the hyperfine structure of the atom.[13]

The ions are counted with a MagneToF ion detector (previously a

micro channel plate was used), and at the end of the beamline the Decay Spectroscopy Station (DSS) allows CRIS to make decay measurements of the isotopes.[14][11]

Results

Prior to the CRIS experiment, the first demonstration of the new fast beam collinear resonance ionization technique at the ISOLDE facility resulted in an efficiency of 0.001%, due to a low duty cycle.[15] In 2008, the CRIS experiment was proposed to implement this technique to simultaneously achieve high efficiency and resolution.[11] Since then, the experiment has demonstrated a 1% experimental efficiency.[10]

In 2012, the CRIS experiment performed their first sensitive measurements of francium isotopes and found good agreement with model predictions of its nuclear structure.[16] Since then, the experiment has been able to make more precision measurements of nuclear structure, including charge radii, electromagnetic dipole and quadrupole moments, and isotope shifts.[1]

Since 2020, the CRIS experiment has been working on a new approach to study short-lived radioactive molecules.[17] These radioactive molecules are promising probes to uncover new physics.[17][18]

External links

References

  1. ^ a b c "CRIS | ISOLDE". isolde.web.cern.ch. Retrieved 2023-07-14.
  2. S2CID 120041351
    .
  3. S2CID 257766596
    .
  4. doi:10.5170/CERN-2013-007.203
    .
  5. S2CID 105204354
    .
  6. doi:10.1016/S0375-9474(01)01625-6
    .
  7. S2CID 254545818
    .
  8. ISBN 978-1-4612-9036-0
    , retrieved 2023-07-14
  9. S2CID 254550467
    .
  10. ^
    ISSN 0168-583X
    .
  11. ^
    S2CID 53655523
    .
  12. ^ Khan, Muhammad Minhaj (26 August 2021). Integration of a Tape Roll for Decay Spectroscopy to Control the Build-Up of Background Radioactivity (Thesis). IMT Atlantique.
  13. ^ "The CRIS Website". isolde-cris.web.cern.ch. Retrieved 2023-07-20.
  14. S2CID 234356572
    .
  15. S2CID 250857276
    .
  16. ^ "Summer Student takes ISOLDE by surprise". CERN. 2023-06-28. Retrieved 2023-07-14.
  17. ^
    PMID 32461650
    .
  18. arXiv:2302.02165. {{cite journal}}: Cite journal requires |journal= (help
    )
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