neutron inelastic scattering measurements at the gelina facility of ec-jrc-irmm a. negret 1, c....

Neutron inelastic scattering Neutron inelastic scattering measurements at the GELINA measurements at the GELINA

facility of EC-JRC-IRMMfacility of EC-JRC-IRMM

A. NegretA. Negret11, C. Borcea, C. Borcea11, A. Plompen, A. Plompen22

1 NIPNE-HH, Romania 2 EC-JRC-IRMM, Belgium

A. Negret - Neutron inelastic scattering measurements at GELINA

Summary

• Introduction

• Experimental setup

• Experimental results: 56Fe(n,n’)

• Data analysis

• Conclusions

A. Negret - Neutron inelastic scattering measurements at GELINA

Summary

• Introduction

• Experimental setup

• Experimental results: 56Fe(n,n’)

• Data analysis

• Conclusions

A. Negret - Neutron inelastic scattering measurements at GELINA Introduction

HH-NIPNE, Romania & EC-JRC-IRMM, Belgium

A. Negret - Neutron inelastic scattering measurements at GELINA Introduction

What do we measure

vn

(N,Z)

n

(N,Z)n

(N,Z)

(N+1,Z-1)

p

(N2,Z2)

(N1,Z1) n

n

Elastic scattering

Inelastic scattering

Nuclear reactions

Fission

Cross section ()

A. Negret - Neutron inelastic scattering measurements at GELINA Introduction

Neutron inelastic scattering

Gamma production cross section

Level cross section

Total cross section

A. Negret - Neutron inelastic scattering measurements at GELINA Introduction

Why do we measure inelastic cross sections

A. Negret - Neutron inelastic scattering measurements at GELINA Introduction

Sensitivity studies

How do we measure

A. Negret - Neutron inelastic scattering measurements at GELINA Introduction

A(n, n’)A(n, 2n)

Primary experimental result:Gamma production cross section

Databases:Level scheme

Level cross sectionTotal inelastic cross section

Uncertainty ~5% for the strongest transitions

Summary

• Introduction

• Experimental setup

• Experimental results: 56Fe(n,n’)

• Data analysis

• Conclusions

A. Negret - Neutron inelastic scattering measurements at GELINA

A. Negret - Neutron inelastic scattering measurements at GELINA Experimental setup

•Electron linac (150 MeV) + 238U target

•Pulse width ~1 ns

•Repetition rate: 800 Hz

•Energy range: 0 – 25 MeV

•Gamma flash from

bremsstrahlung

•Flight path: 200m

(~20 neutrons/burst)

Neutron source: GEel LINear Accelerator (GELINA)

A. Negret - Neutron inelastic scattering measurements at GELINA Experimental setup

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 Inelastic Neutron Scattering (GAINS)

Acquisition Electronics

A. Negret - Neutron inelastic scattering measurements at GELINA Experimental setup

DC440 Acqiris digitizers:• 420 MS/s (2.38 ns/sample)

• 12 bits (4096 amplitude channels)

Summary

• Introduction

• Experimental setup

• Experimental results: 56Fe(n,n’)

• Data analysis

• Conclusions

A. Negret - Neutron inelastic scattering measurements at GELINA

A. Negret - Neutron inelastic scattering measurements at GELINA Results: 56Fe(n,n’)

56Fe(n,n’)

Sample: • natFe (56Fe / natFe = 91.75%) • Thickness: 3mm, 1mm, 4mm• Purity 99.5%

Beam time:• 3 mm sample: 6 weeks• 4 mm sample: 3 weeks• 1 mm sample: 2 weeks• additional checks: 5 weeks

A. Negret - Neutron inelastic scattering measurements at GELINA Results: 56Fe(n,n’)

56Fe(n,n’): gamma spectrum

A. Negret - Neutron inelastic scattering measurements at GELINA Results: 56Fe(n,n’)

846.8 keV gamma production cross section

A. Negret - Neutron inelastic scattering measurements at GELINA Results: 56Fe(n,n’)

1238.3 keV gamma production cross section

A. Negret - Neutron inelastic scattering measurements at GELINA Results: 56Fe(n,n’)

1810.8 keV gamma production cross section

846.8 keV level cross section

A. Negret - Neutron inelastic scattering measurements at GELINA Results: 56Fe(n,n’)

A. Negret - Neutron inelastic scattering measurements at GELINA Results: 56Fe(n,n’)

2085.1 keV level cross section

A. Negret - Neutron inelastic scattering measurements at GELINA Results: 56Fe(n,n’)

Total inelastic level cross section

A. Negret - Neutron inelastic scattering measurements at GELINA

Summary

• Introduction

• Experimental setup

• Experimental results: 56Fe(n,n’)

• Data analysis

• Conclusions

A. Negret - Neutron inelastic scattering measurements at GELINA Data analysis

Sensible points of the analysis: background of the 846.8 keV transition The strongest gamma transition (846.8 keV) may overlap with:

• 72Ge(n,n’): 834 keV + Ge recoil energy

• 27Al(n,n’): 844 keV

A. Negret - Neutron inelastic scattering measurements at GELINA Data analysis

206Pb(n,n’) check

A. Negret - Neutron inelastic scattering measurements at GELINA Data analysis

56Fe(n,n’) with various sample thicknesses

A. Negret - Neutron inelastic scattering measurements at GELINA

Summary

• Introduction

• Experimental setup

• Experimental results: 56Fe(n,n’)

• Data analysis

• Conclusions

A. Negret - Neutron inelastic scattering measurements at GELINA Conclusions

Conclusions

• We measured 56Fe(n,n’) cross sections using the GELINA neutron source and the GAINS gamma spectrometer of EC-JRC-IRMM:

• gamma production cross sections• level cross sections• total inelastic cross section

• Very detailed consistency checks were performed to make sure that the data are reliable.

• Significant differences from the previous measurements persist and remain unexplained.