| 1. |
- Boretzky, K., et al.
(författare)
-
NeuLAND: The high-resolution neutron time-of-flight spectrometer for R 3 B at FAIR
- 2021
-
Ingår i: Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. - : Elsevier BV. - 0168-9002. ; 1014
-
Tidskriftsartikel (refereegranskat)abstract
- NeuLAND (New Large-Area Neutron Detector) is the next-generation neutron detector for the R3B (Reactions with Relativistic Radioactive Beams) experiment at FAIR (Facility for Antiproton and Ion Research). NeuLAND detects neutrons with energies from 100 to 1000 MeV, featuring a high detection efficiency, a high spatial and time resolution, and a large multi-neutron reconstruction efficiency. This is achieved by a highly granular design of organic scintillators: 3000 individual submodules with a size of 5 × 5 × 250 cm3 are arranged in 30 double planes with 100 submodules each, providing an active area of 250 × 250 cm2 and a total depth of 3 m. The spatial resolution due to the granularity together with a time resolution of σt≤ 150 ps ensures high-resolution capabilities. In conjunction with calorimetric properties, a multi-neutron reconstruction efficiency of 50% to 70% for four-neutron events will be achieved, depending on both the emission scenario and the boundary conditions allowed for the reconstruction method. We present in this paper the final design of the detector as well as results from test measurements and simulations on which this design is based.
|
|
| 2. |
- Belushkin, A. V., et al.
(författare)
-
A study of disorder effects at ferroelectric phase transition in BaTiO3
- 2006
-
Ingår i: Physica. B, Condensed matter. - : Elsevier BV. - 0921-4526 .- 1873-2135. ; 385, s. 85-87
-
Tidskriftsartikel (refereegranskat)abstract
- The total structure factor of BaTiO3 obtained by neutron powder diffraction in the temperature range 360-430 K in the vicinity of ferroelectric phase transition has been modeled by the reverse Monte Carlo method. A presence of disordered displacements of Ti atoms due to dynamical tetragonal elongations of unit cells and off-centered sites of Ti atoms in paraelectric phase in the vicinity of the ferroelectric phase transition was observed. Both features result in the anomalous increase of mean square displacements of Ti atoms and reflect the coexistence of displacive and order-disorder components in the ferroelectric phase transition.
|
|
| 3. |
- Golosova, N. O., et al.
(författare)
-
Magnetic and structural properties of FeCO3 at high pressures
- 2017
-
Ingår i: Physical Review B. - : AMER PHYSICAL SOC. - 2469-9950 .- 2469-9969. ; 96:13
-
Tidskriftsartikel (refereegranskat)abstract
- The structural and magnetic properties of siderite FeCO3 have been studied by means of neutron powder diffraction at pressures up to 7.5 GPa and first-principles theoretical calculations. The lattice compression in the rhombohedral calcite-type structure is dominated by the reduction of the Fe-O bonds, while the changes of the C-O bonds are much less pronounced. The Neel temperature of the antiferromagnetic ( AFM) ground state increases substantially under pressure with a coefficient dT(N)/dP = 1.8K/GPa, which is about 1.5 times larger in comparison with those predicted by the empirical Bloch rule. The ab initio calculations were performed in the framework of the density functional theory including Hubbard-U correction. The calculated structural parameters and Neel temperature as functions of pressure provide a reasonable agreement with the experimental results. The analysis of the density of electronic states points toward increased covalent bonding between the Fe and O atoms upon pressure, giving rise to unexpectedly large pressure coefficient of the Neel temperature and reduced ordered magnetic moments of Fe atoms.
|
|
| 4. |
- Alef, S., et al.
(författare)
-
The BGOOD experimental setup at ELSA
- 2020
-
Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-6001 .- 1434-601X. ; 56:4
-
Tidskriftsartikel (refereegranskat)abstract
- The BGOOD experiment at the ELSA facility in Bonn has been commissioned within the framework of an international collaboration. The experiment pursues a systematic investigation of non-strange and strange meson photoproduction, in particular t-channel processes at low momentum transfer. The setup uniquely combines a central almost 4 π acceptance BGO crystal calorimeter with a large aperture forward magnetic spectrometer providing excellent detection of both neutral and charged particles, complementary to other setups such as Crystal Barrel, Crystal Ball, LEPS and CLAS.
|
|
