Tantalum-180m (180mTa) is a rare isotope of tantalum whose decay has never been observed, and whose lifetime is expected to be about a million times longer than the age of the universe.
Modified Majorana module in assembly glovebox with germanium detector crystal and tantalum sample installed. Image credit: Majorana Collaboration.
Tantalum, a chemical element with symbol Ta and atomic number 73, is a rare, hard, blue-gray, shiny transition metal with excellent corrosion resistance.
It has multiple stable isotopes: 2 stable radioisotopes and 35 artificial radioisotopes.
Tantalum-180, the least abundant isotope, occurs naturally in a long-lived excited state.
In an excited state, the protons or neutrons in the nucleus have a higher energy level than normal.
Although energetically possible, radioactive decay of this excited state in tantalum-180m has never been observed before.
Nuclear physicists from the Majorana collaboration are currently conducting experiments aimed at measuring this decay, which is expected to have a lifetime about a million times longer than the age of the universe.
For the experiment, they Majorana Demonstrator At Sanford Underground Research Facility.
Additionally, a significantly larger amount of tantalum samples were introduced compared to tantalum samples previously used in similar studies.
Over the course of a year, they collected data using a series of high-purity germanium detectors with exceptional energy resolution.
They also developed analytical methods specifically tailored to detect multiple expected decay signatures.
As a result of these combined efforts, we were able to establish unprecedented limits that fall within the range of 10.18 up to 1019 Year.
This level of sensitivity represents the first example in which half-life values predicted from nuclear theory have become achievable.
Although the collapse process has not yet been observed, these advances have significantly enhanced existing limits by one to two orders of magnitude.
Additionally, this advance allowed the Majorana team to ignore certain parameter ranges associated with various potential dark matter particles.
“With a new limit of up to 1.5*1019 “This is the most sensitive search for a single β and electron capture decay achieved to date,” the authors said.
“Across all channels, you can exclude attenuation with T1/2<0.29*10.”18For years. ”
of result appear in the diary physical review letter.
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IJ Arnquist other. (Majorana collaboration).Constraints on collapse 180mTa. Physics.pastor rhett 131 (15): 152501; doi: 10.1103/PhysRevLett.131.152501
Source: www.sci.news
