High precision neutron inelastic cross section measurements

Transcription

1 High precision neutron inelastic cross section measurements A. Olacel, C. Borcea, M. Boromiza, A. Negret IFIN-HH, DFN

2 Outline The experimental setup GELINA GAINS Data analysis algorithm. Monte Carlo simulations High precision experimental data: 24 Mg(n, n'γ) 24 Mg nat Ti(n, n'γ) nat Ti 1

3 Experimental setup (EC-JRC Geel) GELINA neutron source Linear accelerator Ee MeV; Δt < 1 ns; Rotating depleted uranium target 0 < E n < 20 MeV Multiuser facility Flight paths l = m Time-of-flight technique High resolution measurements 2

4 Experimental setup (EC-JRC Geel) GAINS (Gamma Array for Inelastic neutron scattering) 12 HPGe detectors, about 100% relative efficiency Detectors at 110, 125, and 150, four detectors at each angle Fission chamber 1.3 m upstream from the sample position to monitor neutron flux 3 Acquiris DC440 digitizers, 12 bit amplitude resolution, 440 MS/s Time of flight method 3

5 HPGe detectors Data analysis algorithm (HPGe detectors) Time-amplitude matrix 4

6 Fission chamber Data analysis algorithm (Fission chamber) Time-amplitude matrix 5

7 Detector efficiencies D. Deleanu et al., Nuclear Instruments and Methods in Physics Research A 624 (2010). 6

8 The multiple scattering of neutrons 7

9 Differential γ-production cross sections Integrated γ-production cross sections 8

10 Level population cross sections Level (kev) Formula Range (kev) Mg 9

11 Total inelastic cross sections Level (kev) Formula Range (kev) Mg 10

12 High precision experimental data Motivation In general: Development of the new generation of nuclear reactors In particular: 24 Mg(n, n'γ) 24 Mg Structural material in the design of nuclear reactors Ingredient of a nuclear fuel EFIT k eff of the SRF Ti(n,n'γ) Ti Structural material in the design of nuclear reactors 48 Ti possible candidate for establishing a standard γ-ray cross section for the neutron induced reactions 11

13 24 Mg(n,n'γ) 24 Mg γ-production cross section Level population cross section Total inelastic cross section A. Olacel et al., PHYSICAL REVIEW C 90, (2014) 12

14 24 Mg(n,n'γ) 24 Mg level density in the compound nucleus 25 Mg Range E n (MeV) Average E n (MeV) E* ( 25 Mg) (MeV) J ( 25 Mg) TALYS Experimental density 1) (MeV -1 ) Theoretical density 2) (MeV -1 ) /2-5/ /2-7/ /2 7/ /2-7/ /2-9/ /2-9/ /2-9/ ) Counted values from the total inelastic cross section 2) Calculated values using: T. von Egidy and D. Bucurescu, Journal of Physics: Conference Series 338 (2012) T. von Egidy and D. Bucurescu, Phys. Rev. C 72, (2005). 13

15 γ-production cross section Ti(n,n'γ) Ti 14

16 Importance of the results In general: Very good neutron energy resolution (approx experimental points) 15

17 Importance of the results In general: Very low total relative uncertainty (<5% for the main transitions) 24 Mg 48 Ti 16

18 Importance of the results In particular: 24 Mg Improving the knowledge of the (n, n γ) reaction cross section on 24 Mg. Reporting cross section data in an extended range (E th 18 MeV). The good agreement between the experimental results and the theoretical calculations indicate that the theoretical model is well performed. 17

19 Importance of the results In particular: 48 Ti Validating the previous experimental results. Reporting more cross section values with very low uncertainty in the plateau area (of interest for the standard cross section evaluators). 18

20 Importance of the results In particular: 46,47,49,50 Ti No previous experimental results. 19

21 Summary Short description of the experimental setup and data analysis procedure. High precision cross section data for the case of 24 Mg and the stable isotopes of titanium emphasizing the motivation of the measurements and the importance of the experimental results. 20

22 Thank you!