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Category: nuclear energy – Page 30

This study has successfully developed a high-efficiency neutron detector array with an exceptionally low background to measure the cross-section of the 13C(α, n)16O reaction at the China Jinping Underground Laboratory (CJPL). Comprising 24 3He proportional counters embedded in a polyethylene moderator, and shielded with 7% borated polyethylene layer, the neutron background at CJPL was as low as 4.5 counts/h, whereby 1.94 counts/h was attributed to the internal α radioactivity. Remarkably, the angular distribution of the 13C(α, n)16O reaction was proven to be a primary variable affecting the detection efficiency. The detection efficiency of the array for neutrons in the range of 0.1MeV to 4.5 MeV was determined using the 51V(p, n)51Cr reaction carried out with the 3 MV tandem accelerator at Sichuan University and Monte Carlo simulations. Future studies can be planned to focus on further improvement of the efficiency accuracy by measuring the angular distribution of 13C(α, n)16O reaction.

Gamow window is the range of energies which defines the optimal energy for reactions at a given temperature in stars. The nuclear cross-section of a nucleus is used to describe the probability that a nuclear reaction will occur. The 13C(α, n)16O reaction is the main neutron source for the slow neutron capture process (s-process) in asymptotic giant branch (AGB) stars, in which the 13C(α, n)16O reaction occurs at the Gamow window spanning from 150 to 230 keV. Hence, it is necessary to precisely measure the cross-section of 13C(α, n)16O reaction in this energy range. A low-background and high detection efficiency neutron detector is the essential equipment to carry out such measurements. This study developed a low-background neutron detector array that exhibited high detection efficiency to address the demands. With such development, advanced studies, including direct cross-section measurements of the key neutron source reactions in stars, can be conducted in the near future.

Low-background neutron detectors play a crucial role in facilitating research related to nuclear astrophysics, neutrino physics, and dark matter. By improving the efficiency and upgrading the technological capability of low background neutron detectors, this study indirectly contributes to the enhancement of scientific research. Additionally, fields involving material science and nuclear reactor technology would also benefit from the perfection of neutron detector technology. Taking into consideration the potential application and expansion of these findings, such innovative attempt aligns well with UNSDG9: Industry, Innovation & Infrastructure.

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Physicist Luke MacQueen combines tissue engineering with stem cell technologies to produce synthetic meat whose texture mimics that of natural meat.

Winston Churchill—the well-known wartime leader and lesser-known Nobel Laureate in Literature—published an essay in 1931 in The Strand Magazine in which he imagined the future “Fifty Years Hence.” Many of his predictions turned out to be prophetic—wireless telephones, television, and nuclear power—while others read like science fiction. But one of his futuristic ideas—growing meat in a lab—may just be a few years away, if Luke MacQueen of Harvard University has his way.

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While the current Oppenheimer blockbuster film focused on the destructive power of nuclear weapons, more peaceful uses of atomic propulsion for space exploration are now gaining once again momentum. ROB COPPINGER reports.

Nuclear fission and fusion power propulsion are under investigation in Europe and the US with an in-space engine demonstration planned by 2027 — with the news last month that Lockheed Martin had been selected to develop a nuclear thermal propulsion system for DARPA’s DRACO programme (see below).

Nuclear propulsion is attractive as it is far more efficient and powerful than conventional chemical rocket engines – with nuclear thermal propulsion (NTP) having twice the propellant efficiency of chemical rockets. SpaceX plans to use its Starship Heavy rocket, propelled by liquid oxygen and methane, to take Elon Musk’s colonists to Mars. NASA’s decades of research have also concluded that NTP is the best choice for crewed missions to the red planet with its Human Exploration of Mars Design Reference Mission 5.0, published in 2009, making clear NTP’s advantages. With NTP, a propellant, liquid hydrogen, is propelled by the heat from a nuclear reactor. It offers a high thrust-to-weight ratio around 10,000 times greater than nuclear electric propulsion (NEP) and two-to-five times greater specific impulse than in-space chemical propulsion.

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Another concern was the dissipation of electrical power on the Enchilada Trap, which could generate significant heat, leading to increased outgassing from surfaces, a higher risk of electrical breakdown and elevated levels of electrical field noise. To address this issue, production specialists designed new microscopic features to reduce the capacitance of certain electrodes.

“Our team is always looking ahead,” said Sandia’s Zach Meinelt, the lead integrator on the project. “We collaborate with scientists and engineers to learn about the kind of technology, features and performance improvements they will need in the coming years. We then design and fabricate traps to meet those requirements and constantly seek ways to further improve.”

Sandia National Laboratories is a multimission laboratory operated by National Technology and Engineering Solutions of Sandia LLC, a wholly owned subsidiary of Honeywell International Inc., for the U.S. Department of Energy’s National Nuclear Security Administration. Sandia Labs has major research and development responsibilities in nuclear deterrence, global security, defense, energy technologies and economic competitiveness, with main facilities in Albuquerque, New Mexico, and Livermore, California.

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Cherenkov radiation achieved in faster than light reactions by SHINE.

SHINE has demonstrated clearly visible Cherenkov radiation produced by fusion for what is believed to be the first time in history. This visible evidence provides further proof that fusion can produce neutrons on par with some nuclear fission reactors.

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The observation of self-heating in magnetically confined plasmas represents a milestone on the road to fusion reactors based on such plasmas.

A fusion reactor would generate electricity using the energy released by nuclear-fusion reactions occurring in a plasma. A key step in the race toward realizing the dream of such a reactor is the creation of a burning plasma—one in which the fusion reactions themselves supply most of the heating needed to keep the plasma at fusion-relevant temperatures. This step has recently been demonstrated for inertially confined plasmas [1, 2] (see Research News: Ignition First in a Fusion Reaction) but has so far remained elusive for magnetically confined ones. This goal could now be within reach thanks to direct evidence for fusion-induced heating of electrons in magnetically confined plasmas obtained by Vasily Kiptily and colleagues at the UK-based Joint European Torus (JET) facility [3].

The fusion of two heavy hydrogen isotopes—deuterium (D) and tritium (T)—presents the most promising path to a fusion reactor, both because of the relative ease in getting these isotopes to fuse and because of the large amount of energy released in each reaction. When D and T fuse, an alpha particle (a helium-4 nucleus) and a neutron are generated, carrying the released energy in the form of kinetic energy. The goal of achieving energy production from controlled fusion on Earth relies on the created alpha particles remaining in the plasma and heating the fusion fuel to keep the reactions going, while the kinetic energy of neutrons escaping the plasma is converted to electrical energy.

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