Applications of neutron spectrometry Neutron sources: 1) Reactors 2) Usage of reactions 3) Spallation sources Neutron show: 1) Where atoms are (structure) – elastic scattering 2) What they are doing (dynamics) – inelastic scattering Neutron diffraction is not useful for highly absorbing materials: Gd, Sm. Eu, Cd, B, Dy... Photon diffraction dos not distinguish different isotopes, neutron can distinguish 1)Introduction 2)Research 3)Application GELINA TOF spectrometer (Belgium) Usage of neutrons at applications: Research of neutron production and transport at different processes Probe to behavior of nuclei, history of spallation reactions and properties of nuclear matter

Neutron diffractometry Usage of inelastic neutron scattering Material research – different physical properties Crystalography – structure of crystals Advantage: 1) see light elements 2) discriminates near elements and isotopes 3) Study of structure properties of large composite samples 4) Study of magnetic properties 5) Possibility of material research also after thick wall Smallangle neutron scattering: structures o 1 – 1000 nm sizes – sensitive to light elements focussing difraktometr Measurement of changes of lattice constant of polycrystalic structures, measurement of micro a macro deformation (study of different type of steels...) Possibility of material research at breaker, laboratory furnace... anisotropy of grains orientation at polycrystallic structures – influence on rigidity and further properties

Spallation reactions as intensive source of neutrons Reaction of protons with high energies ( > 100 MeV ) with nuclei Very intensive source of neutrons – it is possible obtain flux n/cm 2 s Three phases of spallation reaction: 1) Intranuclear cascade - incident proton kicks off in nucleon-nucleon collisions with nucleons with high energies 2) Preequilibrium emission – escape of nucleons with higher energy from nucleus before thermal equilibrium restoration 3) Evaporation of neutrons or nucleus fission – nucleus in thermal equilibrium unloads surplus energy by evaporation of neutrons with energy about 5 MeV. Neutrons are evaporated also by fission fragments High energy nucleons created during intranuclear cascade can produce further spallation reactions - hadron shower This condition is necessary for efective transmutation

Cross sections for ADTT systems and astrophysics Facility n-TOF at CERN Lead target – spallation reaction Proton beam: E p = 20 GeV, Δt = 7 ns, I = 7·10 12 protons, f = 0,8 Hz distance 185 m, 10 5 n/puls/energy order neutron beam with FWHM = 11,8 mm neutron beam: 300 n/p E n = 0,1 eV – 250 MeV Shielding after target deflection magnet lead target - assembling special collimation and moderation for different work regime

Number of fission reaction of 235 U as dependency on neutron energy Spectrum of produced neutrons (simulation) (on the end of transport system m from the target) Energy resolution of n-TOF facility Resonance 80,8 keV at Fe

Measurement of capture on 151 Sm Course of reaction and branch of s-process in the range of Gd, Eu a Sm Detection of gamma by means C 6 D 6 scintillator (small sensitivity on neutrons) Neutrons with energy from 0,6 eV up to 1 MeV Accuracy 6 % 1) Half-life is 93 years – component of nuclear power station waste Study of reaction (n,γ) on 151 Sm 2) Important part of sequence of noble earths production 3) Belongs to transition elements neutron beam gamma detection system background Range 500 – 550 eV

Production of neutrons by spallation reactions and collisions of protons and heavy ions Production of neutrons on uranium Ep = 585 MeV (S. Cierjacks Phys. Rev 36(1987)1976 Proton beam from cyclotrone at SIN (Switzerland) is used – pulse 200 ps Thin targets holes (d=4cm) in 20 cm of iron → narrowly collimated neutron beam to angles 30 o, 90 o and 150 o NE213 – neutron detector NE102A – veto detector – suppression of charged particles 1) Example of measurement of neutron production by spallation reactions on thin targets: target – detector distance is 1,3 m Energy resolution

2) Measurement of neutron production by spallation reactions to zero angle Deflection of beam of charged protons and other particles by magnet Choice only of forward protons produced by neutron collisions (head on collision → total neutron energy is transferred Problems: 1) inelastic processes at convertor n + p → p + n + π 0, n + p → p + p + π - 2) production of other particles n + p → d + π 0, n + p → d + γ 3) background of particles produced in other places 4) accuracy of knowledge of np scattering cross- section as function of energy convertor (liquid hydrogen) – 0,93 g/cm 2 spectrometer: 4 multiwire proportional chambers, 2 before and 2 after magnet (determination of momentum) Proton beam at LAMPF (USA) E = 800 MeV, important materials: Al, Ti, Cu, W, Pb, U Many further experiments studying production of neutrons at spallation reactions and heavy ion collisions Similarly also neutron production on heavy targets

3) Measurement of neutron production on thick targets or complicated set-ups Purpose: to obtain data about neutron production and transport for benchmark of simulation codes Set-up of lead target and uranium blanket Determination of neutron fluencies and spectra by activation method Display of set-up by simulation code MCNPX Example : Set-up „Energy plus Transmutation“ at JINR Dubna Accelerator Nuclotron Activation foils and track detectors

Obtained experimental data Longitudinal distributionRadial distributionE p = 1.5 GeV Measured data: number of produced nuclei at activation sample normalized on proton and gram of sample Example of data: spatial distribution of neutron fluencies Such data can be directly compared with simulations Position along the target [cm] Radial distance [cm] 6 MeV 8 MeV 11 MeV 23 MeV Comparison of experimental data and simulations by means of MCNPX