Science

CERN Physicists Measure Masses of Exotic Indium Nuclei

CERN Physicists Measure Masses of Exotic Indium Nuclei

The isotope tin-100 is of ardour for nuclear structure because of its closed-shell proton and neutron configurations. It is miles moreover the heaviest nucleus comprising protons and neutrons in equal numbers. In contemporary analysis, physicists from the ISOLTRAP experiment at CERN’s Isotope mass Separator On-Line (ISOLDE) facility performed remark mass measurements of indium-99 and indium-100, neighboring nuclei of tin-100. The outcomes seem in the journal Nature Physics.

High-precision mass measurements of neutron-deficient indium isotopes with ISOLTRAP: radioactive atoms were produced by nuclear reactions of 1.4 GeV protons impinging on a thick lanthanum carbide target; short-lived indium atoms diffusing from the target were selectively ionized using a two-step laser excitation scheme, provided by the ISOLDE RILIS, which excited one electron above the indium ionization potential (IP); the extracted ion beam was mass separated and injected into a radiofrequency quadrupole (RFQ) ion trap sitting on a high-voltage (HV) platform, where it was bunched and cooled; the beam was then processed by an MR-ToF MS to separate the indium ions from the isobaric contaminants; when the precision Penning trap was used for the mass measurement, further cooling and purification of the beam was achieved using a helium buffer-gas-filled preparation Penning trap; a position-sensitive microchannel plate (MCP) detector was used to record the time of flight and/or the position of the ion after ejection from the precision Penning trap; in the case of indium-99, for which the production yield was too low, the MR-ToF MS was used to perform the mass measurement. Image credit: Mougeot et al., doi: 10.1038/s41567-021-01326-9.

Excessive-precision mass measurements of neutron-wretched indium isotopes with ISOLTRAP: radioactive atoms were produced by nuclear reactions of 1.4 GeV protons impinging on a thick lanthanum carbide purpose; fast-lived indium atoms diffusing from the aim were selectively ionized the usage of a two-step laser excitation scheme, supplied by the ISOLDE RILIS, which furious one electron above the indium ionization capacity (IP); the extracted ion beam turn out to be as soon as mass separated and injected into a radiofrequency quadrupole (RFQ) ion entice sitting on a excessive-voltage (HV) platform, the effect it turn out to be as soon as bunched and cooled; the beam turn out to be as soon as then processed by an MR-ToF MS to separate the indium ions from the isobaric contaminants; when the precision Penning entice turn out to be as soon as extinct for the mass size, extra cooling and purification of the beam turn out to be as soon as achieved the usage of a helium buffer-fuel-stuffed preparation Penning entice; a position-delicate microchannel plate (MCP) detector turn out to be as soon as extinct to file the time of flight and/or the position of the ion after ejection from the precision Penning entice; in the case of indium-99, for which the manufacturing yield turn out to be as soon as too low, the MR-ToF MS turn out to be as soon as extinct to realize the mass size. Image credit: Mougeot et al., doi: 10.1038/s41567-021-01326-9.

Atomic nuclei have handiest two elements, protons and neutrons, however the relative option of those elements makes a radical difference in their properties.

Distinct configurations of protons and neutrons, with ‘magic numbers’ of protons or neutrons arranged into stuffed shells at some stage in the nucleus, are extra strongly trudge than others.

The uncommon nuclei with total proton and neutron shells, that are termed doubly magic, say particularly enhanced binding energy and are supreme test circumstances for reports of nuclear properties.

The contemporary theoretical calculations and experimental outcomes from the ISOLTRAP personnel clarify one of basically the most iconic doubly magic nuclei: tin-100.

With 50 protons and 50 neutrons, tin-100 is of explicit ardour for reports of nuclear properties because, apart from being doubly magic, it’s a long way the heaviest nucleus comprising protons and neutrons in equal number — a feature that affords it one of the most strongest beta decays, in which a positron is emitted to make a daughter nucleus.

Study of the beta decay of tin-100 suffer from difficulties in producing it.

Moreover, the two most newest such reports — a 2019 ogle by RIKEN and a 2012 ogle by GSI — yield quite heaps of values for the energy released in the decay, ensuing in discrepant values for the mass of tin-100.

Within the contemporary ogle, Dr. Maxime Mougeot of the Max-Planck-Institut für Kernphysik and colleagues measured the mass the unfamiliar unprecedented-proton nucleus indium-100, the beta-decay daughter of tin-100, and of indium-99, with one proton decrease than tin-100.

“The mass of tin-100 is also derived from that of indium-100 and the energy released in the beta decay of tin-100 into indium-100,” Dr. Mougeot said.

“So our indium-100 mass size grabbed this iconic doubly magic nucleus by the tail.”

The contemporary mass size of indium-100 is 90 instances extra exact than the old one, magnifying the discrepancy in the values of the tin-100 mass deduced from basically the most newest beta-decay reports.

The researchers then made comparisons between the measured masses of the indium nuclei and contemporary delicate ab initio theoretical calculations that strive and describe nuclei from first rules.

These comparisons favor the beta-decay energy end result from GSI over that of the RIKEN personnel.

Moreover, they display camouflage supreme settlement between the measurements and the calculations, giving the researchers significant self belief that the calculations to find the intricate nuclear physics of tin-100 and its indium neighbors.

_____

M. Mougeot et al. Mass measurements of 99-101In declare ab initio nuclear theory of the nuclide 100Sn. Nat. Phys, published online September 23, 2021; doi: 10.1038/s41567-021-01326-9