Search results for "Neutron"

The boson peak of deeply cooled confined water reveals the existence of a low-temperature liquid-liquid crossover.

2014

International audience; The Boson peak of deeply cooled water confined in the pores of a silica xerogel is studied by inelastic neutron scattering at different hydration levels to separate the contributions from matrix, water on the pore surfaces and "internal" water. Our results reveal that at high hydration level, where the contribution from internal water is dominant, the temperature dependence of the Boson peak intensity shows an inflection point at about 225 K. The complementary use of differential scanning calorimetry to describe the thermodynamics of the system allows identifying the inflection point as the signature of a water liquid-liquid crossover.

Multiparticle configurations of excited states in 155Lu

2016

Excited states in the neutron-deficient N=84 nuclide 155Lu have been populated by using the 102Pd(58Ni,αp) reaction. The 155Lu nuclei were separated by using the gas-filled recoil ion transport unit (RITU) separator and implanted into the Si detectors of the gamma recoil electron alpha tagging (GREAT) spectrometer. Prompt γ-ray emissions measured at the target position using the JUROGAM Ge detector array were assigned to 155Lu through correlations with α decays measured in GREAT. Structures feeding the (11/2−) and (25/2−)α-decaying states have been revised and extended. Shell-model calculations have been performed and are found to reproduce the excitation energies of several of the low-lyin…

The NEXT Project: Towards Production and Investigation of Neutron-Rich Heavy Nuclides

2022

The heaviest actinide elements are only accessible in accelerator-based experiments on a one-atom-at-a-time level. Usually, fusion–evaporation reactions are applied to reach these elements. However, access to the neutron-rich isotopes is limited. An alternative reaction mechanism to fusion–evaporation is multinucleon transfer, which features higher cross-sections. The main drawback of this technique is the wide angular distribution of the transfer products, which makes it challenging to catch and prepare them for precision measurements. To overcome this obstacle, we are building the NEXT experiment: a solenoid magnet is used to separate the different transfer products and to focus those of …

High-resolution, accurate multiple-reflection time-of-flight mass spectrometry for short-lived, exotic nuclei of a few events in their ground and low…

2019

Physical review / C covering nuclear physics 99(6), 064313 (2019). doi:10.1103/PhysRevC.99.064313

On the physical origin of the protein dynamical transition

2012

Discovery of slow X-ray pulsations in the high-mass X-ray binary 4U 2206+54

2008

Context. The source 4U 2206+54 is one of the most enigmatic high-mass X-ray binaries. In spite of intensive searches, X-ray pul- sations have not been detected in the time range 10−3–103 s. A cyclotron line at ∼30 keV has been suggested by various authors but never detected with significance. The stellar wind of the optical companion is abnormally slow. The orbital period, initially reported to be 9.6 days, disappeared and a new periodicity of 19.25 days emerged. Aims. The main objective of our RXTE monitoring of 4U 2206+54 is to study the X-ray orbital variability of the spectral and timing parameters. The new long and uninterrupted RXTE observations allow us to search for long (∼1 h) puls…

Evidence for Shape Coexistence in Neutron-Rich Rh and Ag Nuclei

1988

Neutron-rich nuclei of Rh and Ag have been investigated by γ-ray spectroscopic measurements as well as single-particle transfer reactions like (d,3He) and (3He,d). The obtained level schemes of 105,107,109,111Rh and 113,115Ag show two different types of excitation: (I) proton-hole states related to a spherical shape of the nucleus and (II) proton-particle states with a rotational band-like structure (intruder band) pointing towards deformation of the nucleus. The “fingerprints” for such a shape coexistence and resulting systematics in these nuclei and the possible interpretation of the intruder band as a rotational band built upon the 1/2+[431] Nilsson configuration are discussed.

A Monte Carlo-aided design of a modular 241Am-Be neutron irradiator

2013

Monte Carlo studies aimed at designing a modular 241Am-Be neutron irradiator for testing neutron detectors and personal dosimeters and processing large volume samples are reported in this study. The evaluation of the shapes and thicknesses of the moderator and shielding materials was carried out by a MCNP5 Monte Carlo simulation code. The reliability of the simulation was experimentally verified by the activation of gold foils and TLD dosimeter measurements in an irradiation cell placed at the center of the test configuration.

Micelles in Mixtures of Sodium Dodecyl Sulfate and a Bolaform Surfactant

2006

Mixtures composed of water, sodium dodecyl sulfate (SDS), and a bolaform surfactant with two aza-crown ethers as polar headgroups (termed Bola C-16) were investigated by modulating the mole ratios between the components. The two surfactants have ionic and nonionic, but ionizable, headgroups, respectively. The ionization is due to the complexation of alkali ions by the aza-crown ether unit(s). Structural, thermodynamic, and transport properties of the above mixtures were investigated. Results from surface tension, translational self-diffusion, and small angle neutron scattering ( SANS) are reported and discussed. Interactions between the two surfactants to form mixed micelles result in a com…

The use of neutron activitacion analysis in the biomonitoring of trace element deposition in the Opole province

2013

Metodą neutronowej analizy aktywacyjnej oznaczono stężenia 42 pierwiastków: Na, Mg, Al, Cl, K, Ca, Sc, V, Cr, Mn, Fe, Ni, Co, Zn, As, Se, Br, Rb, Sr, Zr, Nb, Mo, I, Ag, Cd, Sb, Ba, Cs, La, Ce, Nd, Sm, Eu, Tb, Yb,Hf, Ta, W, Au, Hg, Th i U, zakumulowanych w mchach pobranych do badań we wrześniu i w październiku 2011 roku na terenie województwa opolskiego (południowa Polska). Próbki różnych gatunków mchów pobierano w bliskiej odległości od miejsc przecięcia linii siatki kartograficznej naniesionych na mapę województwa. Odległości pomiędzy punktami wynosiły ok. 20 km. Analiza wyników badań umożliwiła wskazanie miejsc zwiększonej depozycji zanieczyszczeń wraz ze wskazaniem potencjalnych źródeł i…