Precise neutron inelastic cross section measurements

Precise neutron inelastic cross section measurements

A.Negret1

1 “Horia Hulubei” National Institute for Physics and Nuclear Engineering,Bucharest, ROMANIA

Carpathian Summer School of PhysicsCarpathian Summer School of Physics 2012, Sinaia2012, Sinaia

A. Negret - Neutron inelastic cross section measurements

Summary

Introduction

Experimental setup & Analysis

Results for 28Si(n,n’)28Si

Comparison with 25Mg(,n)28Si

Conclusion


IntroductionIntroduction




Conclusion



Neutron data



NEA High priority list

28Si – Gas Cooled Fast Reactors (GFT)

56Fe, 206,207,208Pb – structural materials



(N,Z)

n

What do we measure

v

n(N,Z)

Elastic scattering

Inelastic scattering

Nuclear reactions

Fission

(N2,Z2)

(N1,Z1) n

n

Cross section ()

n

(N,Z)

(N+1,Z-1)

p



Neutron inelastic scattering



Experimental setup & AnalysisIntroduction




Conclusion



Overview of the experimental procedure

Neutron source

200 m flight path

FP3/200 cabin; GAINS + FC



GELINA neutron source

• Electron linac (150 MeV) + 238U target• Pulse width ~1 ns• Repetition rate: 800 Hz• Energy range: 0 – 20 MeV• Gamma flash from

bremsstrahlung• Flight path: 200m

(~550 neutrons/cm2s)



GAINS

8 HPGe detectors @ 110° & 150° (Accurate integration of angular distribution up to the sixth order of Legendre polynomials)

• TOF technique:Amplitude gamma energyTime neutron energy

• Digitizer-based acquisition (Acqiris DC440, 420 MS/s, 12 bits)

• Beam monitoring: 235U Fission chamber

Gamma Array for Inelasic Neutron Scattering



Experimental problems

The gamma flash

Time resolution

Long time measurements

Distance from the neutron source : FP = 200m

Small neutron flux

Stability of the electronics

Simplification of the acquisition system

The digitizer-based acquisition



Overview of the data analysis

8 x HPGE yield FC yield

Efficiency: Monte-Carlo simulation

Multiple scattering correction:Monte-Carlo simulation

Gamma Production cross sections

NDS: level scheme

Total inelastic cross sectionLevel cross sections



ResultsIntroduction




Conclusion



What did we see?

28Si + n28Si+n

29Si



Gamma production cross sections in 28Si



Total inelastic cross section



Level production cross sections





Comparison with 25Mg(,n)28SiIntroduction




Conclusion



28Si + n 28Si+n29Si

28Si(n,n’)28Si vs 25Mg(,n)28Si

25Mg + 25Mg(,n)28Si measurement performed at the Tandem accelerator of IFIN-HH, Bucharest:•The same Compound nucleus, 29Si•The same exit channel•We measured the production cross sections for the same gamma rays:







ConclusionsIntroduction




Conclusion



Conclusions

• The GAINS spectrometer installed at the neutron source GELINArepresents a powerful tool for producing neutron inelastic cross sections

• On-going experiments and analysis for many data sets: 206Pb, natFe, 28Si, 24Mg, 23Na, 12C, 90Zr, 57Fe, natCu.

• Current attempts aim to the development of alternative methods to the direct measurement of neutron-induced cross sections.



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The ERINDA consortium groups 13 partners, equipped with nuclear data research infrastructures. The project sponsors the transnational access for experiments performed at any of the 13 facilities.

The TANDEM accelerator of IFIN-HH is part of ERINDA.

The next (and last) deadline for proposals: September 30, 2012

www.erinda.org

Thank you!



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Precise neutron inelastic cross section measurements