ORNL and CERN Probe 31 Tin Isotopes, Clarify Neutrons' Role in Stability

Scientists working at Oak Ridge National Laboratory and at CERN’s ISOLDE facility have produced a consolidated experimental dataset probing 31 tin isotopes that clarifies how changing neutron number shapes nuclear size, shape and stability. The combined measurements, integrating ORNL Holifield HRIBF experiments from 2002–2012 with more recent ISOLDE laser spectroscopy at CERN, are reported as published in Physical Review Letters and explicitly tied to implications for nuclear energy and national security.

The datasets cover isotopes from roughly 104Sn up to 134Sn. At ISOLDE, the Collinear Resonance Ionization Spectroscopy (CRIS) setup measured neutron‑deficient isotopes from 124Sn down to 104Sn, while the Collinear Laser Spectroscopy (COLLAPS) experiment probed neutron‑rich isotopes from 108Sn up to 134Sn. The ArXiv summary states that these campaigns “extend the available data by four isotopes on the neutron‑deficient side 104−107Sn, while completing the earlier reported radii in with the odd‑even isotopes including 133Sn,” and calls the work “This exceptionally long dataset, span-…ing thirty-one isotopes, serves to reveal intricate changes in the …”

The experimental chain at ISOLDE combined a heated LaCx target run at 1500–2000 °C with a 1.4 GeV proton primary beam to produce reaction recoils that diffused into a heated transfer line. Tin atoms were selectively ionized with the resonant ionization laser ion source (RILIS), electrostatically accelerated to 40 keV, mass‑separated in the high‑resolution mass separator (HRS) with Δm/m ∼ 6000, and bunched in the ISCOOL linear Paul trap prior to spectroscopy. CRIS used two ionization schemes probing the transitions 5s2 5p2 3P1 → 5s2 5p6s 3P2 (284 nm) and 5s2 5p2 1S0 → 5s2 5p7s 1P1 (281 nm). COLLAPS used complementary transitions 5s2 5p2 1S0 → 5p6s 1P1 (452.5 nm) and 5s2 5p2 3P0 → 5p6s 3P1 (286.3 nm) chosen to maximize sensitivity to nuclear observables.

Oak Ridge names on the consolidated report include Alfredo Galindo‑Uribarri, A. Galindo, Steven Pain, Caroline Nesaraja, Kelly A. Chipps, David Radford, James Allwood, Chang Hong Yu, Dan Stracener and B. Alan Tatum. ORNL notes that Holifield’s earlier measurements contributed to establishing the “doubly‑magic” nature of 132Sn and that HRIBF was recognized by the American Physical Society as a historic physics site in 2016. ORNL author credit on the news item reads “– Dawn Levy.”

The collaboration frames these measurements as a tool for refining nuclear structure models and for application to nuclear energy and national security problems. Alfredo Galindo‑Uribarri is quoted: “These studies provided essential insights that help us understand the evolution of nuclear properties.” The combined CRIS and COLLAPS approach at ISOLDE and the ORNL radioactive‑beam work allowed cross‑validation across the long isotopic chain, bridging gaps that isolated studies could not resolve.

Practical follow ups include consulting the Physical Review Letters publication for full figures and tables and the ArXiv manuscript for complete methods and author lists; the ArXiv excerpt lists contact emails fredrik.parnefjord.gustafsson@cern.ch, liss.vazquez.rodriguez@cern.ch and rgarciar@mit.edu and a present address footnote for Texas A&M University, Cyclotron Institute, College Station, TX 77840, USA. Oak Ridge National Laboratory contact information is Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN 37830; (+1) 865.576.7658.