A significant fraction of stars between 7 and 11 solar masses are thought to become supernovae, but the explosion mechanism is unclear. The answer depends critically on the rate of electron capture ...on Ne20 in the degenerate oxygen-neon stellar core. However, because of the unknown strength of the transition between the ground states of Ne20 and F20, it has not previously been possible to fully constrain the rate. By measuring the transition, we establish that its strength is exceptionally large and that it enhances the capture rate by several orders of magnitude. This has a decisive impact on the evolution of the core, increasing the likelihood that the star is (partially) disrupted by a thermonuclear explosion rather than collapsing to form a neutron star. Importantly, our measurement resolves the last remaining nuclear physics uncertainty in the final evolution of degenerate oxygen-neon stellar cores, allowing future studies to address the critical role of convection, which at present is poorly understood
Yields of fission products are essential for designing Radioactive Ion Beam facilities and extracting cross section data to refine reaction models. This work reports the results of irradiations of ...natural uranium targets with a continuous spectrum of fast neutrons. A rapid transport system has been used to bring the targets in front of two segmented Clover detectors operated in coincidence. Decay
γ
-ray spectroscopy of the fission products has allowed for cross sections to be obtained in 61 mass chains, either as independent or as cumulative for the chain. Interpolation versus mass number together with the assumption of a Gaussian distribution of isobars enable cross sections to be evaluated in nearly 80 mass chains. The measurement demonstrates the power of the detectors for twofold
γ
–
γ
events following
β
-decay and indicates that new fission product decay data could be obtained with a dedicated set up.
Forward Diffractive Detector control system for Run 3 in the ALICE experiment Mejía Camacho, J.M.; Rodríguez Ramírez, S.A.; Cabanillas Noris, J.C. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
05/2023, Letnik:
1050
Journal Article
Recenzirano
The ALICE experiment went through major upgrades in preparation for Runs 3 and 4 at the CERN LHC, which foresee a significant increase in the data stream rate. To cope with it, a new Computing System ...Online–Offline (O2) was developed by ALICE and several detectors were upgraded. One of these upgrades corresponded to the ALICE Diffractive (AD) detector, which was replaced by the new Forward Diffractive Detector (FDD). A fundamental system that allows for recording of data as well as for the stable and safe operation of the experimental setup is the Detector Control System (DCS). The DCS controls, monitors, and configures detectors’ hardware and their subsystems among which are commercial hardware and specific custom equipment. In this work, we describe the implementation of the DCS of FDD, which was designed and developed using the SCADA commercial software WinCC Open Architecture (WinCC-OA®) and the Joint Controls Project (JCOP) Framework. We also describe the modeling of FDD-DCS as a finite state machine to be integrated into the ALICE Central DCS, and to be operated by DCS shifters in the run control center and, remotely, by detector experts. This new DCS was developed to comply with the new LHC operational standards that allow for processing the increased luminosity due to collisions at a higher energy, and for fulfilling the specific requirements of the ALICE experiment, in order to address the scientific challenges of its physics program.
The main findings of the LAGUNA Design Study are briefly discussed. Construction of giant underground detectors is technically feasible at several sites. Physics factors will dominate in the site ...selection.
.
In the context of the SPIRAL2 radioactive beam facility the production rate of the neutron-rich
15
C nucleus by
18
O(n,
α
) has been investigated. In a water target of 20 cm
3
, enriched in
18
O ...and placed behind the neutron converter, a rate of a few 10
10
nuclei per second can be reached with 1mA of 40MeV deuterons. A
18
O(n,
α
) cross-section based on the activation method is proposed. It is intermediate between the highest and lowest evaluations available to date.
This article is devoted to study of isobar-analogue states 1− in triplet A=14: 14C-14N-14O. Previously signs of neutron halo in the 1−, 6.09 MeV state of 14C were obtained by two independent groups. ...In this article we propose to study neighbouring nuclei 14N and 14O using the Modified diffraction model (MDM) method and the method of Asymptotic normalization coefficients (ANC). Methods were applied to experimental differential cross sections of 14C(α,α)14C scattering and reactions 13C(3He,d)14N and 14N(3He,t)14O. MDM and ANC gave practically similar within errors radii for the studied 1− states: the 6.09 MeV state in 14C - 2.7±0.1 fm, the 8.06 MeV state in 14N - 2.7 ± 0.1 fm, the 5.17 MeV state in 14O - 2.6 ± 0.2 fm. Moreover, the signs of proton halo in the 1− state of 14N were obtained for the first time.
NEMESIS setup for Indirect Detection of WIMPs Trzaska, W.H.; Barzilov, A.; Enqvist, T. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
10/2022, Letnik:
1040
Journal Article
Recenzirano
Odprti dostop
We summarize the evidence for DM-like anomalies in neutron multiplicity spectra collected underground with Pb targets by three independent experiments: NEMESIS (at 210 m.w.e.) NMDS (at 583 m.w.e.), ...and ZEPLIN-II (at 2850 m.w.e.). A new analysis shows small but persistent anomalies at high neutron multiplicities. Adjusted for differences in detection efficiencies, the positions of the anomalies are consistent between the three systems. Also, the intensities match when corrected for the acquisition time and estimated detection efficiency. While the three measurements are inconclusive when analyzed separately, together, they exclude a statistical fluke to better than one in a million. To prove the existence of the anomalies above the 5-sigma discovery threshold, we propose to upgrade the current NEMESIS setup. The upgrade concept and the critical components of the new experiment are described. The upgraded setup would already acquire the needed data sample during the first year of operation. Additional information, vital for the physics interpretation of the analysis, will be obtained with a Cu target.
PDF
