neutron capture cross sections of 70,72,73,74,76 ge at n_tof ear-1
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Neutron capture cross sections of 70,72,73,74,76 Ge at n_TOF EAR-1. C. Lederer, Goethe University Frankfurt - PowerPoint PPT PresentationTRANSCRIPT
Neutron capture cross sections of 70,72,73,74,76Ge at n_TOF EAR-1
C. Lederer, Goethe University Frankfurt
J. Andrzejewski, M. Barbagallo, E. Chiaveri, C. Domingo-Pardo, R. Dressler, P. Ferreira, I.F. Goncalves, C. Guerrero, F. Gunsing, F. Käppeler, J.Neuhausen, C. Massimi, J. Perkowski, R. Reifarth, D. Schumann, G. Tagliente, J.L. Tain, P.
Vaz, A. Wallner, C. Weiß, and the n_TOF Collaboration
23rd October 2013INTC Meeting,CERN
1
INTC-P-381
Nucleosynthesis above Fe
Fe
Ni
Zn
Ge
Se
r-process (
~50%)
s-process (~ 50% of abundances)
Neutron number
rp, p-process (~1%)
Prot
on n
umbe
r
October 23, 2013 Claudia Lederer INTC Meeting, CERN
s process
Fe
Ni
Zn
Ge
Se
s-process
Neutron number
Prot
on n
umbe
r
October 23, 2013 Claudia Lederer INTC Meeting, CERN
Nuclear Physics Input:• b decay half lives• <s>…. Maxwellian Averaged Cross Section MACS
nnn
nnnnkT dEkTEE
dEkTEEE
)/exp(
)/exp()(2 s
s
nnn
nnnnkT dEkTEE
dEkTEEE
)/exp(
)/exp()(2 s
s
s process
Fe
Ni
Zn
Ge
Se
s-process
Neutron number
Prot
on n
umbe
r
October 23, 2013 Claudia Lederer INTC Meeting, CERN
Nuclear Physics Input:• b decay half lives• <s>…. Maxwellian Averaged Cross Section MACS
kT=8 – 90 keV
s process
October 23, 2013 Claudia Lederer INTC Meeting, CERN
s process
October 23, 2013 Claudia Lederer INTC Meeting, CERN
72Ge(n,g)x2
Mass Number
Rel.
Abun
danc
e Ch
ange
Motivation
Neutron capture cross sections of Ge crucial for• understanding elemental abundances from Ge to Sr• Low background experiments: - GERDA (neutrinoless double b decay of 76Ge) - Dark matter experiments, e.g. CDMS-II (Ge detectors)
October 23, 2013 Claudia Lederer INTC Meeting, CERN
Available Data
72Ge(n,g)
Good et al (1966): Gn for En<40 keV
Maletski et al (1968): Gn for En<30 keVGg for En<4 keV
October 23, 2013 Claudia Lederer INTC Meeting, CERN
Available Data
72Ge(n,g)
Good et al (1966): Gn for En<40 keV
Maletski et al (1968): Gn for En<30 keVGg for En<4 keV
74Ge(n,g)
Good et al (1966): Gn for En<22 keV
Maletski et al (1968): Gn for En<60 keVGg for En<3 keV
October 23, 2013 Claudia Lederer INTC Meeting, CERN
Experimental Setup
• n_TOF EAR-1 – high neutron energy resolution, high neutron flux • C6D6 Detection system – low neutron sensitivity• Samples: enriched GeO2 pellets from ISOFLEX prepared at PSI, cylindrical form, 2 cm diameter
October 23, 2013 Claudia Lederer INTC Meeting, CERN
Countrate Estimate
73Ge 74Ge
72Ge70Ge
Countrate Estimate
73Ge 74Ge
72Ge70Ge
76Ge
Beam Time Request
• n_TOF EAR-1 – high neutron energy resolution, high neutron flux • C6D6 Detection system – low neutron sensitivity• Samples: enriched GeO2 pellets from ISOFLEX prepared at PSI, cylindrical form, 2 cm diameter
• split measurement over 2 experimental campaigns
October 23, 2013 Claudia Lederer INTC Meeting, CERN
Summary
• (n,g) cross sections on Ge isotopes are crucial for understanding s process nucleosynthesis and are important for estimating backgrounds in dark matter and double b decay experiments• Few experimental data on Ge in the keV neutron energy region
Goal:• measure cross section and analyze resonances from thermal up to about 200 keV• MACSs from 10-100 keV with uncertainties <5%
Measurement:• enriched GeO2 samples of 2 g• Measurement at n_TOF EAR-1 - high neutron energy resolution, high neutron flux• C6D6 capture setup - low neutron sensitivity
• 12x1018 protons on target, split over 2 experimental campaigns
October 23, 2013 Claudia Lederer INTC Meeting, CERN
Additional Slides
October 23, 2013 Claudia Lederer INTC Meeting, CERN
Experimental Data
70Ge(n,g)
Good et al (1966): Gn for En<40 keV
Maletski et al (1968): Gn for En<30 keVGg for En<4.5 keV
October 23, 2013 Claudia Lederer INTC Meeting, CERN
Experimental Data
73Ge(n,g)
Maletski et al (1968): Gn for En<9 keVGg for En<2 keV
October 23, 2013 Claudia Lederer INTC Meeting, CERN
Experimental Data
76Ge(n,g)
Good et al (1966): Gn for En<30 keV
Maletski et al (1968): Gn for En<50 keVGg for En<5 keV
October 23, 2013 Claudia Lederer INTC Meeting, CERN
Neutron scattering
October 23, 2013 Claudia Lederer INTC Meeting, CERN