Transcript Document

Precise neutron inelastic cross section
measurements
A. Negret1
1
“Horia Hulubei” National Institute for Physics and Nuclear Engineering,
Bucharest, ROMANIA
Carpathian Summer School of Physics 2012, Sinaia
A. Negret - Neutron inelastic cross section measurements
Summary
Introduction
Experimental setup & Analysis
Results for 28Si(n,n’g)28Si
Comparison with 25Mg(a,ng)28Si
Conclusion
Carpathian Summer School of Physics 2012, Sinaia
A. Negret - Neutron inelastic cross section measurements
Introduction
Introduction
Experimental setup & Analysis
Results for 28Si(n,n’g)28Si
Comparison with 25Mg(a,ng)28Si
Conclusion
Carpathian Summer School of Physics 2012, Sinaia
A. Negret - Neutron inelastic cross section measurements
Neutron data
Carpathian Summer School of Physics 2012, Sinaia
A. Negret - Neutron inelastic cross section measurements
NEA High priority list
– Gas Cooled Fast Reactors
(GFT)
28Si
56Fe, 206,207,208Pb
– structural
materials
Carpathian Summer School of Physics 2012, Sinaia
A. Negret - Neutron inelastic cross section measurements
What do we measure
n
Elastic scattering
(N,Z)
n
Inelastic scattering
v
g
(N,Z)
n
p
(N,Z)
Nuclear reactions
(N+1,Z-1)
Cross section (s)
(N1,Z1)
Fission
n
n
(N2,Z2)
Carpathian Summer School of Physics 2012, Sinaia
A. Negret - Neutron inelastic cross section measurements
Neutron inelastic scattering
Carpathian Summer School of Physics 2012, Sinaia
A. Negret - Neutron inelastic cross section measurements
Experimental setup & Analysis
Introduction
Experimental setup & Analysis
Results for 28Si(n,n’g)28Si
Comparison with 25Mg(a,ng)28Si
Conclusion
Carpathian Summer School of Physics 2012, Sinaia
A. Negret - Neutron inelastic cross section measurements
Overview of the experimental procedure
FP3/200 cabin; GAINS + FC
200 m flight path
Neutron source
Carpathian Summer School of Physics 2012, Sinaia
A. Negret - Neutron inelastic cross section measurements
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)
Carpathian Summer School of Physics 2012, Sinaia
A. Negret - Neutron inelastic cross section measurements
GAINS
Gamma Array for Inelasic Neutron Scattering
8 HPGe detectors @ 110° & 150° (Accurate
integration of angular distribution up to the
sixth order of Legendre polynomials)
• TOF technique:
Amplitude  gamma energy
Time  neutron energy
• Digitizer-based acquisition
(Acqiris DC440, 420 MS/s, 12 bits)
• Beam monitoring: 235U Fission
chamber
Carpathian Summer School of Physics 2012, Sinaia
A. Negret - Neutron inelastic cross section measurements
Experimental problems
The gamma flash
The digitizer-based
acquisition
Time resolution
Distance from the neutron source : FP = 200m
Small neutron flux
Long time measurements
Stability of the electronics
Simplification of the acquisition system
Carpathian Summer School of Physics 2012, Sinaia
A. Negret - Neutron inelastic cross section measurements
Overview of the data analysis
8 x HPGE yield
Efficiency:
Monte-Carlo simulation
FC yield
Multiple scattering correction:
Monte-Carlo simulation
Gamma Production cross sections
NDS: level scheme
Total inelastic cross section
Level cross sections
Carpathian Summer School of Physics 2012, Sinaia
A. Negret - Neutron inelastic cross section measurements
Results
Introduction
Experimental setup & Analysis
Results for 28Si(n,n’g)28Si
Comparison with 25Mg(a,ng)28Si
Conclusion
Carpathian Summer School of Physics 2012, Sinaia
A. Negret - Neutron inelastic cross section measurements
What did we see?
28Si
+n
29Si
28Si+n
Carpathian Summer School of Physics 2012, Sinaia
A. Negret - Neutron inelastic cross section measurements
Gamma production cross sections in 28Si
Carpathian Summer School of Physics 2012, Sinaia
A. Negret - Neutron inelastic cross section measurements
Total inelastic cross section
Carpathian Summer School of Physics 2012, Sinaia
A. Negret - Neutron inelastic cross section measurements
Level production cross sections
Carpathian Summer School of Physics 2012, Sinaia
A. Negret - Neutron inelastic cross section measurements
Comparison with 25Mg(a,ng)28Si
Introduction
Experimental setup & Analysis
Results for 28Si(n,n’g)28Si
Comparison with 25Mg(a,ng)28Si
Conclusion
Carpathian Summer School of Physics 2012, Sinaia
A. Negret - Neutron inelastic cross section measurements
28Si(n,n’g)28Si
28Si
+n
25Mg
+a
29Si
vs
25Mg(a,ng)28Si
28Si+n
25Mg(a,ng)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:
Carpathian Summer School of Physics 2012, Sinaia
A. Negret - Neutron inelastic cross section measurements
28Si(n,n’g)28Si
vs
25Mg(a,ng)28Si
Carpathian Summer School of Physics 2012, Sinaia
A. Negret - Neutron inelastic cross section measurements
28Si(n,n’g)28Si
vs
25Mg(a,ng)28Si
Carpathian Summer School of Physics 2012, Sinaia
A. Negret - Neutron inelastic cross section measurements
Conclusions
Introduction
Experimental setup & Analysis
Results for 28Si(n,n’g)28Si
Comparison with 25Mg(a,ng)28Si
Conclusion
Carpathian Summer School of Physics 2012, Sinaia
A. Negret - Neutron inelastic cross section measurements
Conclusions
• The GAINS spectrometer installed at the neutron source GELINA
represents 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.
Carpathian Summer School of Physics 2012, Sinaia
A. Negret - Neutron inelastic cross section measurements
Advertisement
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
Carpathian Summer School of Physics 2012, Sinaia
A. Negret - Neutron inelastic cross section measurements
Thank you!
Carpathian Summer School of Physics 2012, Sinaia