Precision Neutron Cross Section Measurements at Reactor Neutron Filtered Beams O. Gritzay, V. Kolotyi, O. Kalchenko, V. Libman Institute for Nuclear Research of NAS of Ukraine Prospekt Nauky, 47, Kyiv, Ukraine, The X-th International School-Seminar "THE ACTUAL PROBLEMS OF MICROWORLD PHYSICS", Gomel, Belarus, July , 2009 Olena Gritzay Neutron Physics Department Ukrainian Nuclear Data Center Ukrainian Nuclear Data Center

Content The X-th International School-Seminar "THE ACTUAL PROBLEMS OF MICROWORLD PHYSICS", Gomel, Belarus, July , Actuality 2. Today situation; Reason 3. Ways of problem solving 4. Short characteristics of the KRR 5. Physical basis of NFT 6. Essential principle of NFBT 7. Merits & Demerits of NFT 8. Improvement of filter purity 9. Set of filter components in the NPD 10. Neutron filters used in NPD 11. Components of some filters 12. Procedure of neutron filter creation 13. Fundamental investigations 14. Main systems of experimental equipment 15. Some experimental results New direction in NFBT (developing) 16. New direction in NFBT (developing) 17. Conclusion

Actuality scientific scientific Up-to-date level of development demands technology technology the high accuracy of neutron data the high accuracy of neutron data The X-th International School-Seminar "THE ACTUAL PROBLEMS OF MICROWORLD PHYSICS", Gomel, Belarus, July , 2009 allows to make progress in development of to make progress in development of nuclear simulation codes generation of END libraries THE BASIS FOR ANY TRANSPORT CALCULATIONS for operating & future reactors for nuclear technologies in industry for nuclear technologies in medicine, etc.

Today situation The most difficult situation with the accuracy of NCS is in the energy range from several keV to several 100 keV from several keV to several 100 keV The X-th International School-Seminar "THE ACTUAL PROBLEMS OF MICROWORLD PHYSICS", Gomel, Belarus, July , 2009 Reason The lack of high flux installations for the mentioned energy range from several keV to several 100 keV from several keV to several 100 keV

Ways of problem solving 1) Construction of new facilities similar to ORELA 1) Construction of new facilities similar to ORELA or GELINA with very long flight paths Very expensive !!! 2) neutron filtered beam 2) Use of the neutron filtered beam technique at the existing research reactors The X-th International School-Seminar "THE ACTUAL PROBLEMS OF MICROWORLD PHYSICS", Gomel, Belarus, July , 2009

Short characteristics of the KRR The X-th International School-Seminar "THE ACTUAL PROBLEMS OF MICROWORLD PHYSICS", Gomel, Belarus, July , 2009  The WWR-M KRR is a light water moderated and cooled tank-type reactor with a beryllium reflector  The reactor currently uses 36 % enriched uranium-235 WWR-M2 fuel assemblies, each of which consists of an outer hexagonal tube and two inner cylindrical tubes (today replacement on 20 % U 235 fuel is started)  The nominal thermal power is 10 MW  Neutron flux in the core is about n/cm 2 s  Ten horizontal experimental  Ten horizontal experimental channels (HEC)  The WWR-M KRR is a light water moderated and cooled tank-type reactor with a beryllium reflector  The reactor currently uses 36 % enriched uranium-235 WWR-M2 fuel assemblies, each of which consists of an outer hexagonal tube and two inner cylindrical tubes (today replacement on 20 % U 235 fuel is started)  The nominal thermal power is 10 MW  Neutron flux in the core is about n/cm 2 s  Ten horizontal experimental  Ten horizontal experimental channels (HEC)

P hysical basis of NFT Through these minima the neutrons transmit & form rather narrow quasi-mono-chromatic filtered beams The X-th International School-Seminar "THE ACTUAL PROBLEMS OF MICROWORLD PHYSICS", Gomel, Belarus, July , 2009 The general idea of NFT is transmission of white spectrum through the thick layers of materials, which nuclei have the deep interference minima in their total neutron cross sections

Essential principle of NFBT The X-th International School-Seminar "THE ACTUAL PROBLEMS OF MICROWORLD PHYSICS", Gomel, Belarus, July , n/cm 2 s n/cm 2 s 1 – reactor core, 2 – beryllium reflector; 3 – horizontal channel tube; 4 – beam shutter disks; 5 – preliminary collimator; 6 – filter-assembles ; 7 – filter components ; 8 – outside collimator. 1 – reactor core, 2 – beryllium reflector; 3 – horizontal channel tube; 4 – beam shutter disks; 5 – preliminary collimator; 6 – filter-assembles ; 7 – filter components ; 8 – outside collimator. Reactor (white) spectrum Quasi-mono- energy line

Merits & Demerits of NFT The X-th International School-Seminar "THE ACTUAL PROBLEMS OF MICROWORLD PHYSICS", Gomel, Belarus, July , 2009 MeritsDemerits  Neutron line with energies from thermal to several hundred kilo-electron-volts  Presence of parasitic energy lines in filtered neutron spectrum  High intensity 10 5 – 10 8 n/cm 2 s  Gamma background Quasi -mono-energy of neutron line (economy)  Short reactor time to get high statistical accuracy (economy)  High price of high enriched isotopes Neutron filter technique at research reactors allows to extract from white neutron reactor spectrum a neutron line with certain energy

I mprovement of filter purity (ways of removing I mprovement of filter purity (ways of removing of parasitic energy lines) The X-th International School-Seminar "THE ACTUAL PROBLEMS OF MICROWORLD PHYSICS", Gomel, Belarus, July , ) To take so thick layer of the material that only neutrons, corresponding to the most deep interference minimum, would be able to pass through it 2) To use additional materials, for which resonance maxima in their total neutron cross sections coincide with interference minima for filter material, with the exception of the most deep interference minimum

Set of filter components in the NPD The X-th International School-Seminar "THE ACTUAL PROBLEMS OF MICROWORLD PHYSICS", Gomel, Belarus, July , 2009 The wide set of natural elements and h are used as components for neutron filters The wide set of natural elements and high-pure isotopes are used as components for neutron filters Natural elements: Si, Al, V, Sc, S, Mn, Fe, Ti, Mg, Co, Ce, Cr, Rh, Cu, B, Cd, LiF H isotopes: High-pure isotopes: 52 Сr (99.3%), 54 Fe (99.92%), 56 Fe (99.5%), 57 Fe (99.1%), 58 Ni (99.3%), 60 Ni (92.8– 99.8%), 62 Ni (98.0%), 80 Se(99.2%), 10 B(85%), 7 Li (90%) The wide set of natural elements and h are used as components for neutron filters The wide set of natural elements and high-pure isotopes are used as components for neutron filters Natural elements: Si, Al, V, Sc, S, Mn, Fe, Ti, Mg, Co, Ce, Cr, Rh, Cu, B, Cd, LiF H isotopes: High-pure isotopes: 52 Сr (99.3%), 54 Fe (99.92%), 56 Fe (99.5%), 57 Fe (99.1%), 58 Ni (99.3%), 60 Ni (92.8– 99.8%), 62 Ni (98.0%), 80 Se(99.2%), 10 B(85%), 7 Li (90%)

Set of FC in the NPD (cont.) The X-th International School-Seminar "THE ACTUAL PROBLEMS OF MICROWORLD PHYSICS", Gomel, Belarus, July , 2009 The wide set of filter materials allows to modify filter parameters (purity, intensity, width, etc.) subject to the given research task Through expensiveness of high enriched isotopes, the natural elements or enriched isotopes available in NPD are usually considered as components of new or improved filters New filter 7.5 keV ( exist ): main component Cu New filter 275 keV ( develop ): main component Mn The wide set of filter materials allows to modify filter parameters (purity, intensity, width, etc.) subject to the given research task Through expensiveness of high enriched isotopes, the natural elements or enriched isotopes available in NPD are usually considered as components of new or improved filters New filter 7.5 keV ( exist ): main component Cu New filter 275 keV ( develop ): main component Mn

7.5 keV 275 keV The X-th International School-Seminar "THE ACTUAL PROBLEMS OF MICROWORLD PHYSICS", Gomel, Belarus, July , 2009 Neutron filters used in NPD

Components of some filters The X-th International School-Seminar "THE ACTUAL PROBLEMS OF MICROWORLD PHYSICS", Gomel, Belarus, July , ±0.7 keV filter (g/cm 2 ) 10 B (85%)Sc 60 Ni 54 FeS 59 CoAl ±0.96 keV filter(g/cm 2 ) 24 ±0.96 keV filter (g/cm 2 ) 10 B (85%)SFeAl ±2 keV filter(g/cm 2 ) 54 ±2 keV filter (g/cm 2 ) 10 B (85%)SiSAl ±1.4 keV filter(g/cm 2 ) 133 ±1.4 keV filter (g/cm 2 ) 10 B (85%) 52 Cr 58 Ni 60 NiSiAl

Procedure of neutron filter creation The X-th International School-Seminar "THE ACTUAL PROBLEMS OF MICROWORLD PHYSICS", Gomel, Belarus, July , th step: modeling calculation of neutron filtered spectra using information from ENDF; 2-nd step: creation of filter with components chosen by calculation; 3-rd step: experimental testing of the created filter. If it is necessary the sequence of these steps is repeated.

The X-th International School-Seminar "THE ACTUAL PROBLEMS OF MICROWORLD PHYSICS", Gomel, Belarus, July , 2009 Fundamental investigations  High precision measurements ( with accuracybetter 1% ) of total neutron cross sections, averaged on filter spectrum  High precision measurements ( with accuracy better 1% ) of total neutron cross sections, averaged on filter spectrum  Measurements ( with accuracy3-6% )of neutron scattering cross sections, averaged on filter spectrum  Measurements ( with accuracy 3-6% ) of neutron scattering cross sections, averaged on filter spectrum  Measurements ( with accuracy5-6% )of activation cross sections, averaged on filter spectrum  Measurements ( with accuracy 5-6% ) of activation cross sections, averaged on filter spectrum To determine averaged resonance parameters To estimate self-shielding factor To estimate self-shielding factor To feel resonance parameters of single resonance  High precision measurements ( with accuracybetter 1% ) of total neutron cross sections, averaged on filter spectrum  High precision measurements ( with accuracy better 1% ) of total neutron cross sections, averaged on filter spectrum  Measurements ( with accuracy3-6% )of neutron scattering cross sections, averaged on filter spectrum  Measurements ( with accuracy 3-6% ) of neutron scattering cross sections, averaged on filter spectrum  Measurements ( with accuracy5-6% )of activation cross sections, averaged on filter spectrum  Measurements ( with accuracy 5-6% ) of activation cross sections, averaged on filter spectrum To determine averaged resonance parameters To estimate self-shielding factor To estimate self-shielding factor To feel resonance parameters of single resonance Type of information

The X-th International School-Seminar "THE ACTUAL PROBLEMS OF MICROWORLD PHYSICS", Gomel, Belarus, July , 2009 Main systems of experimental equipment (may be different in configuration and size Main systems of experimental equipment (may be different in configuration and size ) 1) System for forming of filtered neutron beam 1) System for forming of filtered neutron beam 2) System of radiation shielding 2) System of radiation shielding 3) Sample management system 3) Sample management system 4) Neutron detector and counting system 4) Neutron detector and counting system 1) System for forming of filtered neutron beam 1) System for forming of filtered neutron beam 2) System of radiation shielding 2) System of radiation shielding 3) Sample management system 3) Sample management system 4) Neutron detector and counting system 4) Neutron detector and counting system

Forming system of filtered neutron beam The X-th International School-Seminar "THE ACTUAL PROBLEMS OF MICROWORLD PHYSICS", Gomel, Belarus, July , 2009 Preliminary forming of beam - two iron and boron carbide collimators Further forming - in the 1-st three discs of shutter & in outer collimator (in the order lead, textolite and mixture of paraffin with H 3 BO 3 ) The collimation system provides beam narrowing to necessary diameter The elements of neutron filtration system - in the 1-st three disks of shutter & in the outer collimator To facilitate and quicken the procedure of filter changing, special steel containers for filters were made Preliminary forming of beam - two iron and boron carbide collimators Further forming - in the 1-st three discs of shutter & in outer collimator (in the order lead, textolite and mixture of paraffin with H 3 BO 3 ) The collimation system provides beam narrowing to necessary diameter The elements of neutron filtration system - in the 1-st three disks of shutter & in the outer collimator To facilitate and quicken the procedure of filter changing, special steel containers for filters were made includes the elements of beam collimation & neutron filtration

The X-th International School-Seminar "THE ACTUAL PROBLEMS OF MICROWORLD PHYSICS", Gomel, Belarus, July , 2009 Neutron detector and counting system neutron counter, electronic blocks, personal computer and communication lines about 50 m long between spectrometric installation and measuring room E n <= 12 keV - helium-3 counters (СНМ-37, LND 2527) E n >= 12 keV - hydrogen recoil counters (CHM-38, LND 281) E n <= 12 keV - helium-3 counters (СНМ-37, LND 2527) E n >= 12 keV - hydrogen recoil counters (CHM-38, LND 281) ND for σ tot ND for σ tot ND for σ el ND for σ el Five assemblies of 7 He-3 counters СHМ ‑ 17 Set of 7 hydrogen counters LND ‑ 281 Set of 7 helium counters LND ‑ 2527 ND for dσ/dΩ 58 helium-3 counters placed in five layers, located just above the sample

Some experimental results  tot The accuracy  tot is between 0.3% and 1.7% keV Concerning BNL-325 isotope 13 C, part of which in natural carbon makes only 1.1%, has strong p-resonance with energy ±1.4 keV (J=2, Гn=3.7 ± 0.7 keV, Гγ=4.0 ± 1.6 keV) The X-th International School-Seminar "THE ACTUAL PROBLEMS OF MICROWORLD PHYSICS", Gomel, Belarus, July , 2009

Some experimental results (cont.) In energy region from 50 keV to 60 keV isotope Cr-52 has 2 resonances with energies ~ 50 keV and ~58 keV. In energy region from 50 keV to 60 keV isotope Cr-52 has 2 resonances with energies ~ 50 keV and ~ 58 keV. How can we get information about resonance parameters? 52 Cr

New direction in NFBT (developing) The X-th International School-Seminar "THE ACTUAL PROBLEMS OF MICROWORLD PHYSICS", Gomel, Belarus, July , 2009 of σ tot, averaged on filter spectra, the main energy of which are shifted 1) Set of σ tot, averaged on filter spectra, the main energy of which are shifted How can we get information about resonance parameters by NFBT?

The X-th International School-Seminar "THE ACTUAL PROBLEMS OF MICROWORLD PHYSICS", Gomel, Belarus, July , 2009 New direction in NFBT (cont.) owing to dependence energy of scattering neutrons from angle of scattering 1) Shift of the main energy of filter owing to dependence energy of scattering neutrons from angle of scattering

New direction in NFBT (cont.) The X-th International School-Seminar "THE ACTUAL PROBLEMS OF MICROWORLD PHYSICS", Gomel, Belarus, July , 2009 of 2) Set of the averaged the averaged tot σ tot using filter the main energy line the main energy line of which of which is cutted into 2 or 3 parts parts How can we get information about resonance parameters by NFBT?

Conclusion 1.NFBT at research reactors allows to get experimental data with high accuracy in energy region from thermal to several hudreed keV σ tot < 1%; σ el <3-4%; dσ el /dΩ <5-6%; σ n,γ <5-6% 2.New directions (shift & cutting main filter line) will allow to get information about resonance parameters The X-th International School-Seminar "THE ACTUAL PROBLEMS OF MICROWORLD PHYSICS", Gomel, Belarus, July , 2009 to make progress in development of nuclear simulation codes generation of END libraries THE BASIS FOR ANY TRANSPORT CALCULATIONS for operating & future reactors for nuclear technologies in industry for nuclear technologies in medicine, etc.

Conference chairman : Ivan M. Vyshnevskyi (Director of KINR) Scientific secretary : Vitali Yu. Denisov (KINR) Website: Collective processes in atomic nucleiNeutron and reactor physics, nuclear data Nuclear reactionsProblems of atomic energy Nuclear structure and decay processes Applied nuclear physics in medicine&industry Rare nuclear processesExperimental facilities&detection techniques TOPICS

The X-th International School-Seminar "THE ACTUAL PROBLEMS OF MICROWORLD PHYSICS", Gomel, Belarus, July , 2009 Thank You for your attention!