Теннессийн их сургуулийн судлаачид CERN-ийн ISOLDE байгууламжид хийсэн туршилтаараа алт, цагаан алт зэрэг хүнд элементүүд сансарт хэрхэн үүсдэгийг тайлбарлах шинэ мэдээлэл олж авлаа.
Судлаачид нейтрон оддын мөргөлдөөн болон оддын дэлбэрэлтийн үед явагддаг “нейтрон хурдан барих үйл явц”-ын нэгэн чухал шатыг индий-134 изотоп дээр судалжээ. Энэхүү богино настай изотопын задралын үед ялгарсан нейтронуудын энергийг анх удаа нарийвчлан хэмжсэнээр, эрдэмтэд 20 жилийн турш хайсан цагаан тугалга-133 (tin-133)-ын цөмийн төлөвийг илрүүлж чадсан байна.
Туршилтын явцад ажиглагдсан нэгэн сонирхолтой үзэгдэл бол цөмийн “ой санамж” юм. Задралын дараа ч үүссэн цөм нь өмнөх бүтцийнхээ шинж чанарыг хадгалж үлдэж байгаа нь тогтоогджээ.
Гэсэн хэдий ч судалгааны үр дүн одоогийн онолын загваруудад бүрэн нийцээгүй байна. Тухайлбал, задралын явцад цөмийн төлөвүүд бүрэлдэн тогтох статистик хэв маяг нь таамаглаж байснаас өөр байсан нь энэхүү нарийн төвөгтэй үйл явцыг бүрэн тайлбарлахад одоогийн шинжлэх ухаанд цоорхой байгааг харуулж байна.
Дэлгэрэнгүйг эх сурвалжаас харах
↓Эх сурвалжийг нээх ↓
A team working at CERN has reported three discoveries that provide fresh insight into the nuclear reactions behind the creation of heavy elements during violent cosmic events. The research, published in Physical Review Letters, focuses on a key stage of the rapid neutron capture process, which is thought to produce elements such as gold and platinum during neutron star mergers and stellar explosions.
Heavy elements are among the most intriguing products of the cosmos. Researchers have long linked their formation to the process, a chain of reactions that takes place in environments packed with neutrons. Even so, many of the nuclear processes involved remain difficult to observe directly because they occur in highly unstable atomic nuclei.
To learn more, a team led by physicists from the University of Tennessee studied indium-134, a short-lived isotope that exists only briefly before decaying. Their work at CERN’s ISOLDE Decay Station has revealed new details about how exotic nuclei behave and how heavy elements may emerge from these extreme conditions.
A Closer Look At A Rare Nuclear Process
The rapid neutron capture process begins when atomic nuclei rapidly capture neutrons. As they become heavier, they also become less stable and eventually break apart or decay, giving rise to new elements.
One of the least understood parts of this sequence involves beta decay followed by the emission of two neutrons. Because the nuclei involved are so short-lived, studying this process has proven particularly challenging.
The researchers focused on indium-134, which decays into excited forms of tin-132, tin-133, and tin-134. Using a specialized neutron detector developed with support from the National Science Foundation, the team measured the energy of neutrons released during this decay for the first time. Robert Grzywacz, a professor involved in the project, said that:
“These nuclei are hard to make and require a lot of new technology to synthesize in sufficient quantities”
The data could help researchers better understand the nuclear reactions that contribute to the formation of heavy elements in space.
A Missing Piece Of The Puzzle Appears
The study also confirmed the existence of a nuclear state that scientists had been searching for over many years. During the experiment, the team detected a predicted neutron state in tin-133 that had never been observed directly. Its existence had been suggested by theory, but experimental confirmation had remained elusive.
“People were searching for it for 20 years and we found it. Those two neutrons allowed us to see this state”, said Grzywacz.
Researchers also observed an unexpected phenomenon. Even after the decay process, the nucleus appeared to retain traces of its earlier structure. The team described this behavior as a form of nuclear “memory,” suggesting that characteristics of the original configuration persist in the daughter nucleus.
Results That Do Not Fit Current Models
Not all of the findings matched expectations. When researchers examined the newly observed state in greater detail, they found that its behavior differed from what existing theories predicted. The way the state was populated during decay did not follow the statistical patterns expected by current models.
The study reports that this mismatch appeared even though the experiment was conducted under carefully controlled conditions. That makes the result especially interesting for physicists trying to understand nuclei that lie far from stability.
Rather than confirming established ideas, the measurements point to gaps in current theoretical descriptions. The researchers say the findings show that some aspects of these unusual nuclear systems are still not fully understood.
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